Gastrointestinal dynamics of superabsorbent polymers: Insights from a murine model

Gastrointestinal dynamics of superabsorbent polymers: Insights from a murine model | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Gastrointestinal dynamics of superabsorbent polymers: Insights from a murine model Taichi Nakatani, Harunori Miyauchi, Yuichi Okata, Yuko Bitoh This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8060722/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose Superabsorbent polymers (SAPs) are widely used materials that pose a risk of pediatric intestinal obstruction following accidental ingestion. However, in vivo gastrointestinal dynamics of SAPs remain unclear. Methods We developed a murine model to determine the temporal changes in SAP localization and size following ingestion. The results were compared with the in vitro behavior of SAPs. Additionally, the effects of the co-administration of water on SAP behavior in vivo were also assessed. Results In vitro , SAPs rapidly expanded within 1 h, and the extent of expansion was strongly influenced by pH and the composition of the solution. In vivo , SAPs enlarged more gradually, reaching maximum size in the cecum approximately 4 h after ingestion and subsequently shrinking during colonic passage until excretion, thereby reducing the risk of intestinal obstruction. Co-administration of water accelerated SAP expansion, delayed gastrointestinal transit, and increased particle size, particularly in the small intestine and cecum, suggesting that dietary and fluid management should be carefully considered in patients with accidental SAP ingestion. Conclusions SAP gradually expanded from the stomach to the small intestine and shrank during expulsion through the colon. The simultaneous administration of water accelerated SAP expansion and delayed gastrointestinal transit. pediatric bowel obstruction mouse model superabsorbent polymers children foreign body ingestion Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Superabsorbent polymers (SAPs) are hydrophilic, cross-linked polymers capable of absorbing and retaining water hundreds to thousands of times their dry weight, forming swollen, gel-like structures. Consequently, SAPs are widely used in diapers, sanitary products, agricultural water retention materials, air fresheners, and bead-shaped toys. Bead-shaped SAP products (SAPBs) are colorful, smooth, and candy-like, making them highly attractive to children and posing a risk of accidental ingestion. In recent years, numerous cases of pediatric intestinal obstruction and death due to the accidental ingestion of SAPBs have been reported. Over 90% of ingested foreign bodies that pass through the pylorus are naturally expelled within two weeks [ 1 ]. SAPBs easily pass through the esophagus and stomach because they are only a few millimeters in diameter at ingestion. However, once in the gastrointestinal tract, they absorb luminal fluid and expand, thereby increasing the risk of intestinal obstruction beyond the pylorus, which often requires emergency surgical intervention [ 2 – 5 ]. Previous in vitro studies have shown that SAPs swell rapidly when immersed in sufficient liquid, and that this process is strongly influenced by environmental pH and ionic composition [ 2 , 4 , 6 – 8 ]. Furthermore, in an ex vivo model, SAPs that had previously expanded in distilled water significantly shrank compared with controls after a 4-h exposure to Gastrografin in the small intestine [ 8 ]. However, the in vivo gastrointestinal environment is far more complex, involving dynamic factors such as intestinal peristalsis, digestive fluid secretion, and pH fluctuations [ 6 ]. Therefore, the gastrointestinal dynamics of SAPs remain poorly understood. The present study aimed to address this knowledge gap by developing a murine model of SAP ingestion. Using this model, we performed a temporal analysis of SAP localization and expansion in the gastrointestinal tract to elucidate the in vivo dynamics of SAP. Methods Animals The 8-week-old C57BL/6N mice used in this study were bred and maintained at the Institute of Experimental Animal Research of Kobe University Graduate School of Medicine under specific pathogen-free conditions. All animal experiments were performed in compliance with the Kobe University Animal Experimentation Regulations, and the study was approved by the Institutional Animal Care and Use Committee (permission number: P240901). Intragastric administration of SAP A spherical SAP (PHUXENY, China) with an initial diameter of 2.00 mm was quartered, with one quarter administered per mouse. Intragastric delivery was performed using an etched polytetrafluoroethylene (PTFE) liner (inner diameter, 1.27 mm; wall thickness, 25 µm; Junkosha, Tokyo, Japan) as the outer tube, combined with a 20G 30-mm Surflo needle (Terumo, Tokyo, Japan) as the inner tube. The SAP fragment was loaded at the tip of the outer tube, and both tubes were advanced until the inner tube was approximately 2.5-cm inside the mouse’s mouth. The inner tube was then pushed in to deliver the SAP directly into the stomach while holding the outer tube in place. In vitro behavior of SAPs A total of 30 SAP quarters were immersed in water, a pH 7 buffer solution, or a pH 4 acidic solution (10 quarters per solution) and incubated at room temperature for 6 h. The long-axis length and mass were measured every hour. The long axis length was measured with a digital caliper to a precision of 0.1 mm, and the mass was measured to a precision of 0.1 µg. SAP monotherapy in vivo Mice were euthanized 1, 2, 3, 4, 5, or 6 h after intragastric administration of an SAP quarter, and the entire gastrointestinal tract from the stomach to the rectum was excised. The location, long axis, mid-axis, short axis, and mass of the SAP were measured. Co-administration of SAPs and water in vivo SAP quarters were administered to mice with 0.1–0.4 mL of water. Mice were euthanized 5 h after administration, and the gastrointestinal tract was removed to determine the location and size of the SAP fragments. Euthanasia and specimen collection Mice were euthanized by inducing respiratory depression through intraperitoneal injection of ketamine and xylazine, followed by cervical dislocation. Statistical analysis Continuous variables are presented as the mean ± standard deviation. Fisher’s exact test was used to compare categorical variables between the groups. Statistical significance was set at p < 0.05. Statistical analyses were performed using JMP Pro software version 18 (SAS Institute, Cary, NC, USA). Results SAP behavior in vitro The initial long-axis length and mass of the SAP were 2.00 mm and 1.26 µg, respectively. After a 1-h immersion in tap water, a pH 7 buffer solution, and a pH 4 acidic solution, the SAPs were 9.84 ± 0.24, 6.27 ± 0.35, and 5.64 ± 0.37 mm in length, respectively, with masses of 221.71 ± 34.09, 37.78 ± 4.44, and 32.56 ± 4.67 µg, respectively (Table 1 ). In all three solutions, both the long axis length and the mass increased sharply within 1 h, and subsequently plateaued. Maximum expansion was observed in tap water, with relatively less expansion in the pH 7 and pH 4 solutions (Fig. 1 ). These results suggest that SAP expansion depends on the pH of the solution and its ionic composition. Table 1 Size measurements of superabsorbent polymers at different time points after immersion in tap water and different pH solutions Solution Immersion time (h) 0 1 2 3 4 5 6 Water (mm) 2 9.84 ± 0.24 10.30 ± 0.38 10.71 ± 0.48 10.38 ± 0.35 10.18 ± 0.42 10.15 ± 0.41 pH 7 (mm) 2 6.27 ± 0.35 6.22 ± 0.31 6.51 ± 0.18 6.28 ± 0.38 6.29 ± 0.29 6.13 ± 0.26 pH 4 (mm) 2 5.64 ± 0.37 5.43 ± 0.32 5.54 ± 0.24 5.10 ± 0.20 5.16 ± 0.21 5.00 ± 0.12 SAP behavior in vivo Figure 2 shows an SAP fragment in a distal ileum resected 4 h after SAP administration. The temporal changes in SAP localization within the intestine are illustrated in Fig. 3a. At 1 h post-administration, the majority of SAP fragments (83.3%) remained in the stomach; however, by 2 h, 57.1% had migrated to the small intestine. By 5 h, 81.8% had reached the cecum and beyond, and by 6 h, all SAP fragments had been excreted in feces. Notably, none of the mice exhibited signs of intestinal obstruction, such as intestinal dilatation at the proximal end of the SAP retention site. The size of the SAP fragments recovered from the gastrointestinal tract gradually increased between 0 and 4 h, to a long-axis length of 3.99 ± 0.38 mm and a mass of 15.3 ± 4.80 µg at 4 h and decreased after 5 h (Fig. 3b; Table 2 ). Figure 4 shows the size and weight of SAP fragments recovered from various locations 1–6 h after ingestion. The SAP fragments tended to expand as they progressed distally through the intestinal tract from the stomach to the small intestine and cecum, and were largest in the cecum, with a maximum mass of 16.7 ± 4.93 µg (Table 3 ). The lengths of the long and short axis also peaked in the cecum. SAP fragments were smaller in the colon than in the cecum, and SAP fragments excreted in the feces exhibited a further reduction in both size and weight. The SAP mass differed significantly between the cecum and feces (p = 0.0426), suggesting that SAP contraction occurred in the colon during excretion. Table 2 Size of superabsorbent polymers over time after ingestion in in vivo experiments in mice Parameter Time after administration (h) 0 1 2 3 4 5 6 Long axis (mm) 2.00 3.90 ± 0.98 3.74 ± 0.63 4.05 ± 0.74 3.99 ± 0.38 4.00 ± 0.82 3.10 ± 0.47 Mid-axis (mm) 1.30 2.70 ± 0.48 2.71 ± 0.41 2.85 ± 0.51 2.89 ± 0.52 2.66 ± 0.65 2.45 ± 0.37 Short axis (mm) 1.00 1.85 ± 0.25 1.86 ± 0.52 2.17 ± 0.16 2.14 ± 0.45 1.88 ± 0.45 1.55 ± 0.42 Mass (µg) 1.26 10.1 ± 7.49 9.8 ± 3.87 14.0 ± 4.06 15.3 ± 4.80 9.0 ± 6.95 5.2 ± 3.40 Table 3 Average size measurements of superabsorbent polymers extracted from various locations in the digestive tract of mice Parameter Location Stomach Small intestine Cecum Colon Feces Long axis (mm) 3.61 ± 0.70 4.06 ± 0.55 4.70 ± 0.62 4.18 ± 0.75 3.28 ± 0.58 Mid-axis (mm) 2.48 ± 0.48 3.02 ± 0.36 2.85 ± 0.62 2.98 ± 0.64 2.42 ± 0.36 Short axis (mm) 1.81 ± 0.33 2.11 ± 0.41 2.23 ± 0.17 2.08 ± 0.63 1.58 ± 0.35 Mass (µg) 10.3 ± 7.00 12.6 ± 4.60 16.7 ± 4.93 11.8 ± 7.29 5.20 ± 3.19 Effects of simultaneous water administration on SAP behavior in vivo SAP localization within the intestinal tract 5 h after the simultaneous administration of SAP fragments and 0–0.4 mL of water is illustrated in Fig. 5 a. In mice that received no water, 63.6% of SAP fragments had reached the colon or feces by 5 h after ingestion. In contrast, only 21.7% of SAP fragments reached the colon or feces by 5 h after ingestion in mice that also received water, indicating a significant delay in gastrointestinal transit (p = 0.0239). The size and weight of the recovered SAP fragments varied according to the volume of water administered, with 0.2-mL water associated with the greatest expansion (long-axis length, 4.89 ± 1.22 mm; mid-axis length, 3.47 ± 0.88 mm; short-axis length, 2.29 ± 0.67 mm; mass, 23.0 ± 1 5.0 µg) (Fig. 5 b; Table 4 ). SAP fragments recovered from the small intestine to cecum of mice co-administered with water exhibited a significantly larger long axis (5.13 ± 0.20 vs 4.22 ± 0.25 mm, p = 0.010), mid-axis (3.56 ± 0.15 vs 2.98 ± 0.18 mm, p = 0.024), and mass (24.6 ± 2.8 vs 14.4 ± 3.7 µg, p = 0.043) than those recovered from mice that did not receive water (Table 5 ). Table 4 Volume measurements of superabsorbent polymers administered with different amounts of water Parameter Volume of water co-administered (mL) 0 0.1 0.2 0.3 0.4 Long axis (mm) 4.00 4.24 ± 0.96 4.89 ± 1.22 4.46 ± 1.24 3.60 ± 0.85 Mid-axis (mm) 2.66 3.08 ± 0.59 3.47 ± 0.88 3.24 ± 0.78 2.73 ± 0.66 Short axis (mm) 1.88 2.13 ± 0.52 2.29 ± 0.67 2.26 ± 0.56 1.92 ± 0.44 Mass (µg) 9.0 14.8 ± 9.59 23.0 ± 15.0 16.8 ± 13.7 9.60 ± 7.71 Table 5 Superabsorbent polymer fragment size according to water co-administration Parameter Water co-administration p-value No (n = 9) Yes (n = 13) Long axis (mm) 4.22 ± 0.25 5.13 ± 0.20 0.01 Mid-axis (mm) 2.98 ± 0.18 3.56 ± 0.15 0.024 Short axis (mm) 2.16 ± 0.15 2.43 ± 0.12 0.165 Mass (µg) 14.4 ± 3.7 24.6 ± 2.8 0.043 These results indicate that simultaneous administration of water promotes SAP expansion, thereby delaying gastrointestinal transit. Discussion To the best of our knowledge, this study is the first to analyze the temporal gastrointestinal dynamics and expansion of SAPs in vivo . The results demonstrated that the SAP fragments gradually expanded from the stomach to the small intestine, reaching a maximum size in the cecum, and shrinking during expulsion through the colon. The simultaneous administration of water accelerated SAP expansion and delayed gastrointestinal transit. Previous in vitro studies have shown that SAPs expand rapidly, typically within 1–2 h, and that the extent of the swelling is dependent on factors such as pH and solution composition [ 2 , 4 , 6 – 8 ]. Our in vitro results are consistent with these findings. However, in our in vivo model, SAP expansion followed a slower trajectory, with maximal swelling occurring 4 h after ingestion. This discrepancy suggests that the physiological environment substantially influences SAP expansion. Factors such as fluctuating luminal pH, intestinal peristalsis, digestive secretions, electrolytes, and dynamic changes in intestinal fluid volume likely contribute to the deceleration of water absorption and modulation of maximal swelling capacity. These findings highlight the complexity of the gastrointestinal milieu and the difficulty in fully reproducing it in vitro . the findings emphasize the importance of biological models for the accurate assessment of the in vivo behavior of SAPs. We also observed that the gastric transit of SAP fragments required approximately 2 h, with nearly half of the ingested particles being expelled during this period. A magnetic resonance imaging–based study determined that the gastric half-life of solid food is 59 ± 5 min in mice [ 9 ], indicating that SAPs are retained in the stomach longer than typical digested solids. This difference is most likely attributable to the relatively large size and intact nature of SAP particles, which reduces their ability to pass through the pyloric sphincter than foods that have been mechanically and chemically broken down. These findings suggest that SAPs persist in the stomach after ingestion, potentially influencing their expansion. In the present study, SAPs were found to expand predominantly in the small intestine and cecum, where they reach maximal size, and subsequently decrease in volume during passage through the colon. This observation is clinically relevant, as a review of 43 pediatric patients who had accidentally ingested SAPs reported a median time to symptom onset of 1 day (range: 15 h to 2 days). Most cases required surgical intervention due to obstruction of the small intestine; no obstructions were reported in the colon [ 2 ]. The absence of colonic obstruction in clinical practice is consistent with our findings, suggesting that SAP particles undergo natural shrinkage in the colon as part of physiological transit. Although previous in vitro studies have demonstrated that hyperosmolar substances such as Gastrografin or honey can induce SAP shrinkage through osmotic effects [ 8 ], the present study provides in vivo evidence that shrinkage occurs naturally in the colon under physiological conditions. This represents an important advancement in understanding the fate of SAPs after ingestion and offers a mechanistic explanation for the distribution of obstruction sites observed in the clinic. Notably, simultaneous administration of SAP fragments and 0.2 mL of water led to marked SAP swelling and delayed gastrointestinal transit. This suggests that increasing water intake following accidental ingestion may promote SAP expansion and prolong its retention within the small intestine, thereby increasing the risk of intestinal obstruction. Currently, no standardized treatment process exists for SAP ingestion. However, some studies have advocated for conservative management with fasting (nil per os) [ 6 ]. Our findings support this strategy by demonstrating that fluid restriction inhibits excessive expansion and may reduce the likelihood of intestinal blockage. Clinically, these results suggest that dietary and fluid management should be carefully considered in pediatric patients presenting with accidental SAP ingestion. Limitations This study had several limitations. First, only one SAP, of uniform size and composition and from a single manufacturer, was examined; commercially available products vary widely in size, structure, and material properties. Therefore, future research should incorporate a broader range of SAPs to improve generalizability. Second, this was a preliminary study conducted in mice, and caution is therefore required when extrapolating to human clinical scenarios. Notably, we were unable to establish an obstruction model, probably because of the relatively short intestinal transit time in mice, which limited exposure to luminal fluids and enabled rapid expulsion before full SAP expansion. Furthermore, the size of particles that can be safely administered to mice is inherently limited, which constrains the degree of swelling that can be achieved. To overcome these challenges, the use of alternative animal models with gastrointestinal physiology more comparable to that of humans, such as pigs and dogs, should be considered in future work. These larger animal models also offer the advantages of being able to administer larger SAP particles, with longer transit times, and more clinically relevant insights. Conclusions To the best of our knowledge, this is the first study to evaluate the in vivo dynamics and swelling of SAPs in a mouse model. The SAP fragments gradually expanded from the stomach to the small intestine, reached maximum size in the cecum, and shrank during expulsion through the colon. The simultaneous administration of water accelerated SAP expansion and delayed gastrointestinal transit. These results suggest that once SAPs reach the colon, they tend to shrink, thereby reducing the risk of intestinal obstruction. Conversely, water consumption after ingestion may increase the risk of intestinal obstruction. Clinically, this indicates the need to consider management guidelines, including the possibility of fluid restriction. However, the application of these findings to human clinical settings requires further verification. Declarations Author Contributions Taichi Nakatani: Conceptualization, Investigation, Methodology, Performed the experiments, Writing – Original draft, Writing – Reviewing and Editing. Harunori Miyauchi: Conceptualization, Methodology, Investigation, Writing – Reviewing and Editing. Yuichi Okata: Conceptualization, Methodology, Investigation, Writing – Reviewing and Editing. Yuko Bitoh: Conceptualization, Methodology, Investigation, Writing – Reviewing and Editing. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work. Data Availability : Not applicable. Funding/Support: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Compliance with Ethical Standards Competing Interest :The authors have no competing interests to declare that are relevant to the content of this article. Research Involving Animals: All animal experiments were performed in compliance with the Kobe University Animal Experimentation Regulations, and the study was approved by the Institutional Animal Care and Use Committee (permission number: P240901). References Jackson J, Randell KA, Knapp JF (2015) Two year old with water bead ingestion. Pediatr Emerg Care 31:605–607. https://doi.org/10.1097/PEC.0000000000000520 Caré W, Dufayet L, Paret N, Manel J, Laborde-Casterot H, Blanc-Brisset I, Langrand J, Vodovar D (2022) Bowel obstruction following ingestion of superabsorbent polymers beads: literature review. Clin Toxicol 60:159–167. https://doi.org/10.1080/15563650.2021.1987452 Bollettini T, Mogiatti M, Benigna A, Finelli A, Ferrara F, Pardi V, Macchiarelli R, Messina M, Gentilino V, Molinaro F, Angotti R (2025) Water beads: Expanding toy and ‘new’ problem for paediatric surgeons and community. 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Will drinking Gastrografin help to flush it out? J Surg Res 304:273–279. https://doi.org/10.1016/j.jss.2024.10.036 Chavero-Pieres M, Viola MF, Appeltans I, Abdurahiman S, Gsell W, Matteoli G, Himmelreich U, Boeckxstaens G (2023) Magnetic resonance imaging as a non-invasive tool to assess gastric emptying in mice. Neurogastroenterol Motil 35:e14490. https://doi.org/10.1111/nmo.14490 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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07:44:30","extension":"png","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":9055,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinegroupimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/f4c68ca7389e1e71f71864b5.png"},{"id":97141058,"identity":"cf9cc8cc-6ba2-441b-ab0c-ad498f0a4199","added_by":"auto","created_at":"2025-12-01 10:06:10","extension":"png","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8527,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinegroupimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/e9055baa05a50e6d3bef800b.png"},{"id":97119369,"identity":"aa4721cd-74e0-4295-96de-8bc6c7f6623c","added_by":"auto","created_at":"2025-12-01 07:44:30","extension":"png","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":15679,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinegroupimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/9f4d31bf109c4975dce8fa2e.png"},{"id":97141961,"identity":"f6b10560-9e71-464c-b7e8-fa0d910ef52f","added_by":"auto","created_at":"2025-12-01 10:07:13","extension":"xml","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":65260,"visible":true,"origin":"","legend":"","description":"","filename":"c9ed41eb9dad4b6799c72d83b8a8d32e1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/27f47a2c811f295b68bb6011.xml"},{"id":97119376,"identity":"c03be6da-9ec3-430a-a39d-2f884391eacf","added_by":"auto","created_at":"2025-12-01 07:44:30","extension":"html","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":72796,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/f13436111b73818d496f07d1.html"},{"id":97142049,"identity":"bf7bb084-31fd-4728-aa20-82a691de8f89","added_by":"auto","created_at":"2025-12-01 10:07:18","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":50118,"visible":true,"origin":"","legend":"\u003cp\u003eSwelling of superabsorbent polymers after immersion in various solutions, as shown by their long axis length and mass\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/49cb2d32bbb608d5e28dec6f.jpg"},{"id":97119353,"identity":"a3d5d31f-9025-4f3b-9e38-07a25350093e","added_by":"auto","created_at":"2025-12-01 07:44:29","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":96295,"visible":true,"origin":"","legend":"\u003cp\u003eSuperabsorbent polymer (SAP) fragment in a distal ileum resected 4 h after SAP administration (left panel) and the SAP fragment after removal from the ileum (right panel).\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/367638ffe2138a68ba45d785.jpg"},{"id":97119356,"identity":"8b3e62db-c965-4125-ba58-2e5d69ba349c","added_by":"auto","created_at":"2025-12-01 07:44:29","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":138548,"visible":true,"origin":"","legend":"\u003cp\u003eSuperabsorbent polymer (SAP) behavior \u003cem\u003ein vivo\u003c/em\u003e. (a) Proportion of SAP fragments found in various locations 1–6 h after oral administration. (b) Size and (c) weight of SAP fragments 0–6 h after oral administration.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/47886deef9bb9701f48f38b5.png"},{"id":97119357,"identity":"65a7850e-90a8-4b28-b113-a3f3a599eaf4","added_by":"auto","created_at":"2025-12-01 07:44:29","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":66428,"visible":true,"origin":"","legend":"\u003cp\u003eSuperabsorbent polymer fragment size and weight according to location\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/ff0d673844b0d45d5eeb7081.jpg"},{"id":97141583,"identity":"5c82aade-8f43-4bf2-b2c7-b98b7c919b5d","added_by":"auto","created_at":"2025-12-01 10:06:50","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":123772,"visible":true,"origin":"","legend":"\u003cp\u003eSuperabsorbent polymer (SAP) behavior \u003cem\u003ein vivo\u003c/em\u003efollowing co-administration with water. (a) Proportion of SAP fragments found in various locations 5 h after administration of water. (b) Size and (c) weight of SAP fragments 5 h after administration of water.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/f03fabeb7df6d92d45c9d968.png"},{"id":98430421,"identity":"7fc8b80b-8be9-4791-8f98-2f56471ed3d4","added_by":"auto","created_at":"2025-12-17 16:45:24","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1230459,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8060722/v1/c380ff1d-4bce-42e8-a56b-9ecbd2cd03b8.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Gastrointestinal dynamics of superabsorbent polymers: Insights from a murine model","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSuperabsorbent polymers (SAPs) are hydrophilic, cross-linked polymers capable of absorbing and retaining water hundreds to thousands of times their dry weight, forming swollen, gel-like structures. Consequently, SAPs are widely used in diapers, sanitary products, agricultural water retention materials, air fresheners, and bead-shaped toys. Bead-shaped SAP products (SAPBs) are colorful, smooth, and candy-like, making them highly attractive to children and posing a risk of accidental ingestion. In recent years, numerous cases of pediatric intestinal obstruction and death due to the accidental ingestion of SAPBs have been reported.\u003c/p\u003e\u003cp\u003eOver 90% of ingested foreign bodies that pass through the pylorus are naturally expelled within two weeks [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. SAPBs easily pass through the esophagus and stomach because they are only a few millimeters in diameter at ingestion. However, once in the gastrointestinal tract, they absorb luminal fluid and expand, thereby increasing the risk of intestinal obstruction beyond the pylorus, which often requires emergency surgical intervention [\u003cspan additionalcitationids=\"CR3 CR4\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePrevious \u003cem\u003ein vitro\u003c/em\u003e studies have shown that SAPs swell rapidly when immersed in sufficient liquid, and that this process is strongly influenced by environmental pH and ionic composition [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Furthermore, in an ex vivo model, SAPs that had previously expanded in distilled water significantly shrank compared with controls after a 4-h exposure to Gastrografin in the small intestine [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. However, the \u003cem\u003ein vivo\u003c/em\u003e gastrointestinal environment is far more complex, involving dynamic factors such as intestinal peristalsis, digestive fluid secretion, and pH fluctuations [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Therefore, the gastrointestinal dynamics of SAPs remain poorly understood.\u003c/p\u003e\u003cp\u003eThe present study aimed to address this knowledge gap by developing a murine model of SAP ingestion. Using this model, we performed a temporal analysis of SAP localization and expansion in the gastrointestinal tract to elucidate the \u003cem\u003ein vivo\u003c/em\u003e dynamics of SAP.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eAnimals\u003c/h2\u003e\u003cp\u003eThe 8-week-old C57BL/6N mice used in this study were bred and maintained at the Institute of Experimental Animal Research of Kobe University Graduate School of Medicine under specific pathogen-free conditions. All animal experiments were performed in compliance with the Kobe University Animal Experimentation Regulations, and the study was approved by the Institutional Animal Care and Use Committee (permission number: P240901).\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eIntragastric administration of SAP\u003c/h3\u003e\n\u003cp\u003eA spherical SAP (PHUXENY, China) with an initial diameter of 2.00 mm was quartered, with one quarter administered per mouse. Intragastric delivery was performed using an etched polytetrafluoroethylene (PTFE) liner (inner diameter, 1.27 mm; wall thickness, 25 \u0026micro;m; Junkosha, Tokyo, Japan) as the outer tube, combined with a 20G 30-mm Surflo needle (Terumo, Tokyo, Japan) as the inner tube. The SAP fragment was loaded at the tip of the outer tube, and both tubes were advanced until the inner tube was approximately 2.5-cm inside the mouse\u0026rsquo;s mouth. The inner tube was then pushed in to deliver the SAP directly into the stomach while holding the outer tube in place.\u003c/p\u003e\n\u003ch3\u003eIn vitro behavior of SAPs\u003c/h3\u003e\n\u003cp\u003eA total of 30 SAP quarters were immersed in water, a pH 7 buffer solution, or a pH 4 acidic solution (10 quarters per solution) and incubated at room temperature for 6 h. The long-axis length and mass were measured every hour. The long axis length was measured with a digital caliper to a precision of 0.1 mm, and the mass was measured to a precision of 0.1 \u0026micro;g.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSAP monotherapy\u003c/b\u003e \u003cb\u003ein vivo\u003c/b\u003e\u003c/p\u003e\u003cp\u003eMice were euthanized 1, 2, 3, 4, 5, or 6 h after intragastric administration of an SAP quarter, and the entire gastrointestinal tract from the stomach to the rectum was excised. The location, long axis, mid-axis, short axis, and mass of the SAP were measured.\u003c/p\u003e\u003cp\u003e\u003cb\u003eCo-administration of SAPs and water\u003c/b\u003e \u003cb\u003ein vivo\u003c/b\u003e\u003c/p\u003e\u003cp\u003eSAP quarters were administered to mice with 0.1\u0026ndash;0.4 mL of water. Mice were euthanized 5 h after administration, and the gastrointestinal tract was removed to determine the location and size of the SAP fragments.\u003c/p\u003e\n\u003ch3\u003eEuthanasia and specimen collection\u003c/h3\u003e\n\u003cp\u003eMice were euthanized by inducing respiratory depression through intraperitoneal injection of ketamine and xylazine, followed by cervical dislocation.\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eContinuous variables are presented as the mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. Fisher\u0026rsquo;s exact test was used to compare categorical variables between the groups. Statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05. Statistical analyses were performed using JMP Pro software version 18 (SAS Institute, Cary, NC, USA).\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eSAP behavior\u003c/b\u003e \u003cb\u003ein vitro\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe initial long-axis length and mass of the SAP were 2.00 mm and 1.26 \u0026micro;g, respectively. After a 1-h immersion in tap water, a pH 7 buffer solution, and a pH 4 acidic solution, the SAPs were 9.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24, 6.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35, and 5.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37 mm in length, respectively, with masses of 221.71\u0026thinsp;\u0026plusmn;\u0026thinsp;34.09, 37.78\u0026thinsp;\u0026plusmn;\u0026thinsp;4.44, and 32.56\u0026thinsp;\u0026plusmn;\u0026thinsp;4.67 \u0026micro;g, respectively (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). In all three solutions, both the long axis length and the mass increased sharply within 1 h, and subsequently plateaued. Maximum expansion was observed in tap water, with relatively less expansion in the pH 7 and pH 4 solutions (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). These results suggest that SAP expansion depends on the pH of the solution and its ionic composition.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSize measurements of superabsorbent polymers at different time points after immersion in tap water and different pH solutions\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eSolution\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"7\" nameend=\"c8\" namest=\"c2\"\u003e\u003cp\u003eImmersion time (h)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWater (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e9.84\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e10.30\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e10.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e10.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e10.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e10.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH 7 (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e6.27\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e6.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e6.51\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e6.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e6.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e6.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH 4 (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e5.64\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e5.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e5.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e5.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e5.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e5.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eSAP behavior\u003c/b\u003e \u003cb\u003ein vivo\u003c/b\u003e\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows an SAP fragment in a distal ileum resected 4 h after SAP administration. The temporal changes in SAP localization within the intestine are illustrated in Fig.\u0026nbsp;3a. At 1 h post-administration, the majority of SAP fragments (83.3%) remained in the stomach; however, by 2 h, 57.1% had migrated to the small intestine. By 5 h, 81.8% had reached the cecum and beyond, and by 6 h, all SAP fragments had been excreted in feces. Notably, none of the mice exhibited signs of intestinal obstruction, such as intestinal dilatation at the proximal end of the SAP retention site.\u003c/p\u003e\u003cp\u003eThe size of the SAP fragments recovered from the gastrointestinal tract gradually increased between 0 and 4 h, to a long-axis length of 3.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38 mm and a mass of 15.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.80 \u0026micro;g at 4 h and decreased after 5 h (Fig.\u0026nbsp;3b; Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the size and weight of SAP fragments recovered from various locations 1\u0026ndash;6 h after ingestion. The SAP fragments tended to expand as they progressed distally through the intestinal tract from the stomach to the small intestine and cecum, and were largest in the cecum, with a maximum mass of 16.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.93 \u0026micro;g (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The lengths of the long and short axis also peaked in the cecum. SAP fragments were smaller in the colon than in the cecum, and SAP fragments excreted in the feces exhibited a further reduction in both size and weight. The SAP mass differed significantly between the cecum and feces (p\u0026thinsp;=\u0026thinsp;0.0426), suggesting that SAP contraction occurred in the colon during excretion.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSize of superabsorbent polymers over time after ingestion in \u003cem\u003ein vivo\u003c/em\u003e experiments in mice\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"7\" nameend=\"c8\" namest=\"c2\"\u003e\u003cp\u003eTime after administration (h)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLong axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e3.90\u0026thinsp;\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e3.74\u0026thinsp;\u0026plusmn;\u0026thinsp;0.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e4.05\u0026thinsp;\u0026plusmn;\u0026thinsp;0.74\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e3.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e4.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0.82\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e3.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.47\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMid-axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e2.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e2.71\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e2.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e2.66\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e2.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eShort axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e1.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e1.86\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e2.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e1.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e1.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMass (\u0026micro;g)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e10.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e9.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.87\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e14.0\u0026thinsp;\u0026plusmn;\u0026thinsp;4.06\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e15.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.80\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e9.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e5.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eAverage size measurements of superabsorbent polymers extracted from various locations in the digestive tract of mice\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eLocation\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eStomach\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSmall intestine\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCecum\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eColon\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eFeces\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLong axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e3.61\u0026thinsp;\u0026plusmn;\u0026thinsp;0.70\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e4.06\u0026thinsp;\u0026plusmn;\u0026thinsp;0.55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e4.70\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e4.18\u0026thinsp;\u0026plusmn;\u0026thinsp;0.75\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e3.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.58\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMid-axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e2.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e3.02\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e2.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.64\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e2.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eShort axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e1.81\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e2.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e2.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e1.58\u0026thinsp;\u0026plusmn;\u0026thinsp;0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMass (\u0026micro;g)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e10.3\u0026thinsp;\u0026plusmn;\u0026thinsp;7.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e12.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e16.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e11.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e5.20\u0026thinsp;\u0026plusmn;\u0026thinsp;3.19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eEffects of simultaneous water administration on SAP behavior\u003c/b\u003e \u003cb\u003ein vivo\u003c/b\u003e\u003c/p\u003e\u003cp\u003eSAP localization within the intestinal tract 5 h after the simultaneous administration of SAP fragments and 0\u0026ndash;0.4 mL of water is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003ea. In mice that received no water, 63.6% of SAP fragments had reached the colon or feces by 5 h after ingestion. In contrast, only 21.7% of SAP fragments reached the colon or feces by 5 h after ingestion in mice that also received water, indicating a significant delay in gastrointestinal transit (p\u0026thinsp;=\u0026thinsp;0.0239).\u003c/p\u003e\u003cp\u003eThe size and weight of the recovered SAP fragments varied according to the volume of water administered, with 0.2-mL water associated with the greatest expansion (long-axis length, 4.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.22 mm; mid-axis length, 3.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.88 mm; short-axis length, 2.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67 mm; mass, 23.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1 5.0 \u0026micro;g) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e5\u003c/span\u003eb; Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eSAP fragments recovered from the small intestine to cecum of mice co-administered with water exhibited a significantly larger long axis (5.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20 vs 4.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25 mm, p\u0026thinsp;=\u0026thinsp;0.010), mid-axis (3.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15 vs 2.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18 mm, p\u0026thinsp;=\u0026thinsp;0.024), and mass (24.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8 vs 14.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7 \u0026micro;g, p\u0026thinsp;=\u0026thinsp;0.043) than those recovered from mice that did not receive water (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eVolume measurements of superabsorbent polymers administered with different amounts of water\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"5\" nameend=\"c6\" namest=\"c2\"\u003e\u003cp\u003eVolume of water co-administered (mL)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.4\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLong axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e4.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e4.89\u0026thinsp;\u0026plusmn;\u0026thinsp;1.22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e4.46\u0026thinsp;\u0026plusmn;\u0026thinsp;1.24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e3.60\u0026thinsp;\u0026plusmn;\u0026thinsp;0.85\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMid-axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e3.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e3.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e3.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.78\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e2.73\u0026thinsp;\u0026plusmn;\u0026thinsp;0.66\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eShort axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e1.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e2.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e2.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e2.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e1.92\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMass (\u0026micro;g)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e9.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e14.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e23.0\u0026thinsp;\u0026plusmn;\u0026thinsp;15.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e16.8\u0026thinsp;\u0026plusmn;\u0026thinsp;13.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e9.60\u0026thinsp;\u0026plusmn;\u0026thinsp;7.71\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003e\u003cb\u003eSuperabsorbent polymer fragment size according to water co-administration\u003c/b\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eParameter\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eWater co-administration\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNo (n\u0026thinsp;=\u0026thinsp;9)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eYes (n\u0026thinsp;=\u0026thinsp;13)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLong axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e4.22\u0026thinsp;\u0026plusmn;\u0026thinsp;0.25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e5.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMid-axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e2.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e3.56\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.024\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eShort axis (mm)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e2.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e2.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.165\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMass (\u0026micro;g)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e14.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e24.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.043\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThese results indicate that simultaneous administration of water promotes SAP expansion, thereby delaying gastrointestinal transit.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eTo the best of our knowledge, this study is the first to analyze the temporal gastrointestinal dynamics and expansion of SAPs \u003cem\u003ein vivo\u003c/em\u003e. The results demonstrated that the SAP fragments gradually expanded from the stomach to the small intestine, reaching a maximum size in the cecum, and shrinking during expulsion through the colon. The simultaneous administration of water accelerated SAP expansion and delayed gastrointestinal transit.\u003c/p\u003e\u003cp\u003ePrevious \u003cem\u003ein vitro\u003c/em\u003e studies have shown that SAPs expand rapidly, typically within 1\u0026ndash;2 h, and that the extent of the swelling is dependent on factors such as pH and solution composition [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Our \u003cem\u003ein vitro\u003c/em\u003e results are consistent with these findings. However, in our \u003cem\u003ein vivo\u003c/em\u003e model, SAP expansion followed a slower trajectory, with maximal swelling occurring 4 h after ingestion. This discrepancy suggests that the physiological environment substantially influences SAP expansion. Factors such as fluctuating luminal pH, intestinal peristalsis, digestive secretions, electrolytes, and dynamic changes in intestinal fluid volume likely contribute to the deceleration of water absorption and modulation of maximal swelling capacity. These findings highlight the complexity of the gastrointestinal milieu and the difficulty in fully reproducing it \u003cem\u003ein vitro\u003c/em\u003e. the findings emphasize the importance of biological models for the accurate assessment of the in vivo behavior of SAPs.\u003c/p\u003e\u003cp\u003eWe also observed that the gastric transit of SAP fragments required approximately 2 h, with nearly half of the ingested particles being expelled during this period. A magnetic resonance imaging\u0026ndash;based study determined that the gastric half-life of solid food is 59\u0026thinsp;\u0026plusmn;\u0026thinsp;5 min in mice [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], indicating that SAPs are retained in the stomach longer than typical digested solids. This difference is most likely attributable to the relatively large size and intact nature of SAP particles, which reduces their ability to pass through the pyloric sphincter than foods that have been mechanically and chemically broken down. These findings suggest that SAPs persist in the stomach after ingestion, potentially influencing their expansion.\u003c/p\u003e\u003cp\u003eIn the present study, SAPs were found to expand predominantly in the small intestine and cecum, where they reach maximal size, and subsequently decrease in volume during passage through the colon. This observation is clinically relevant, as a review of 43 pediatric patients who had accidentally ingested SAPs reported a median time to symptom onset of 1 day (range: 15 h to 2 days). Most cases required surgical intervention due to obstruction of the small intestine; no obstructions were reported in the colon [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The absence of colonic obstruction in clinical practice is consistent with our findings, suggesting that SAP particles undergo natural shrinkage in the colon as part of physiological transit. Although previous \u003cem\u003ein vitro\u003c/em\u003e studies have demonstrated that hyperosmolar substances such as Gastrografin or honey can induce SAP shrinkage through osmotic effects [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], the present study provides \u003cem\u003ein vivo\u003c/em\u003e evidence that shrinkage occurs naturally in the colon under physiological conditions. This represents an important advancement in understanding the fate of SAPs after ingestion and offers a mechanistic explanation for the distribution of obstruction sites observed in the clinic.\u003c/p\u003e\u003cp\u003eNotably, simultaneous administration of SAP fragments and 0.2 mL of water led to marked SAP swelling and delayed gastrointestinal transit. This suggests that increasing water intake following accidental ingestion may promote SAP expansion and prolong its retention within the small intestine, thereby increasing the risk of intestinal obstruction. Currently, no standardized treatment process exists for SAP ingestion. However, some studies have advocated for conservative management with fasting (nil per os) [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Our findings support this strategy by demonstrating that fluid restriction inhibits excessive expansion and may reduce the likelihood of intestinal blockage. Clinically, these results suggest that dietary and fluid management should be carefully considered in pediatric patients presenting with accidental SAP ingestion.\u003c/p\u003e\n\u003ch3\u003eLimitations\u003c/h3\u003e\n\u003cp\u003eThis study had several limitations. First, only one SAP, of uniform size and composition and from a single manufacturer, was examined; commercially available products vary widely in size, structure, and material properties. Therefore, future research should incorporate a broader range of SAPs to improve generalizability. Second, this was a preliminary study conducted in mice, and caution is therefore required when extrapolating to human clinical scenarios. Notably, we were unable to establish an obstruction model, probably because of the relatively short intestinal transit time in mice, which limited exposure to luminal fluids and enabled rapid expulsion before full SAP expansion. Furthermore, the size of particles that can be safely administered to mice is inherently limited, which constrains the degree of swelling that can be achieved. To overcome these challenges, the use of alternative animal models with gastrointestinal physiology more comparable to that of humans, such as pigs and dogs, should be considered in future work. These larger animal models also offer the advantages of being able to administer larger SAP particles, with longer transit times, and more clinically relevant insights.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eTo the best of our knowledge, this is the first study to evaluate the \u003cem\u003ein vivo\u003c/em\u003e dynamics and swelling of SAPs in a mouse model. The SAP fragments gradually expanded from the stomach to the small intestine, reached maximum size in the cecum, and shrank during expulsion through the colon. The simultaneous administration of water accelerated SAP expansion and delayed gastrointestinal transit. These results suggest that once SAPs reach the colon, they tend to shrink, thereby reducing the risk of intestinal obstruction. Conversely, water consumption after ingestion may increase the risk of intestinal obstruction. Clinically, this indicates the need to consider management guidelines, including the possibility of fluid restriction. However, the application of these findings to human clinical settings requires further verification.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTaichi Nakatani:\u003c/strong\u003e Conceptualization, Investigation, Methodology,\u0026nbsp;Performed the experiments,\u0026nbsp;Writing – Original draft, Writing – Reviewing and Editing.\u0026nbsp;\u003cstrong\u003eHarunori Miyauchi:\u003c/strong\u003e Conceptualization, Methodology, Investigation, Writing – Reviewing and Editing. \u003cstrong\u003eYuichi Okata:\u003c/strong\u003e Conceptualization, Methodology, Investigation, Writing – Reviewing and Editing. \u003cstrong\u003eYuko Bitoh:\u003c/strong\u003e Conceptualization, Methodology, Investigation, Writing – Reviewing and Editing. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e: Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding/Support:\u0026nbsp;\u003c/strong\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompliance with Ethical Standards\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interest\u003c/strong\u003e:The authors have no competing interests to declare that are relevant to the content of this article.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResearch Involving Animals:\u003c/strong\u003e All animal experiments were performed in compliance with the Kobe University Animal Experimentation Regulations, and the study was approved by the Institutional Animal Care and Use Committee (permission number: P240901).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eJackson J, Randell KA, Knapp JF (2015) Two year old with water bead ingestion. Pediatr Emerg Care 31:605\u0026ndash;607. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/PEC.0000000000000520\u003c/span\u003e\u003cspan address=\"10.1097/PEC.0000000000000520\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCar\u0026eacute; W, Dufayet L, Paret N, Manel J, Laborde-Casterot H, Blanc-Brisset I, Langrand J, Vodovar D (2022) Bowel obstruction following ingestion of superabsorbent polymers beads: literature review. Clin Toxicol 60:159\u0026ndash;167. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/15563650.2021.1987452\u003c/span\u003e\u003cspan address=\"10.1080/15563650.2021.1987452\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBollettini T, Mogiatti M, Benigna A, Finelli A, Ferrara F, Pardi V, Macchiarelli R, Messina M, Gentilino V, Molinaro F, Angotti R (2025) Water beads: Expanding toy and \u0026lsquo;new\u0026rsquo; problem for paediatric surgeons and community. J Paediatr Child Health 61:204\u0026ndash;208. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jpc.16730\u003c/span\u003e\u003cspan address=\"10.1111/jpc.16730\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZamora IJ, Vu LT, Larimer EL, Olutoye OO (2012) Water-absorbing balls: A growing problem. Pediatrics 130:e1011\u0026ndash;e1014. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1542/peds.2011-3685\u003c/span\u003e\u003cspan address=\"10.1542/peds.2011-3685\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eArana A, Hauser B, Hachimi-Idrissi S, Vandenplas Y (2001) Management of ingested foreign bodies in childhood and review of the literature. Eur J Pediatr 160:468\u0026ndash;472. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s004310100788\u003c/span\u003e\u003cspan address=\"10.1007/s004310100788\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHachem JJ, Monagas J, Banerjee A, Noel RA (2025) Unpacking the dangers of super absorbent polymer water beads: an \u003cem\u003ein vitro\u003c/em\u003e analysis. Front Pediatr 13:1477506. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fped.2025.1477506\u003c/span\u003e\u003cspan address=\"10.3389/fped.2025.1477506\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDarracq MA, Cullen J, Rentmeester L, Cantrell FL, Ly BT (2015) Orbeez: the magic water absorbing bead\u0026ndash;risk of pediatric bowel obstruction. Pediatr Emerg Care 31:416\u0026ndash;418. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/PEC.0000000000000304\u003c/span\u003e\u003cspan address=\"10.1097/PEC.0000000000000304\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWilliams J, Pumiglia L, Zhang B, Francis A, Prey B, Ciullo S, Horton J, Barlow M (2024) The itsy-bitsy water bead went down the baby\u0026rsquo;s mouth. Will drinking Gastrografin help to flush it out? J Surg Res 304:273\u0026ndash;279. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jss.2024.10.036\u003c/span\u003e\u003cspan address=\"10.1016/j.jss.2024.10.036\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChavero-Pieres M, Viola MF, Appeltans I, Abdurahiman S, Gsell W, Matteoli G, Himmelreich U, Boeckxstaens G (2023) Magnetic resonance imaging as a non-invasive tool to assess gastric emptying in mice. Neurogastroenterol Motil 35:e14490. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/nmo.14490\u003c/span\u003e\u003cspan address=\"10.1111/nmo.14490\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"pediatric bowel obstruction, mouse model, superabsorbent polymers, children, foreign body ingestion","lastPublishedDoi":"10.21203/rs.3.rs-8060722/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8060722/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e\u003cp\u003eSuperabsorbent polymers (SAPs) are widely used materials that pose a risk of pediatric intestinal obstruction following accidental ingestion. However, \u003cem\u003ein vivo\u003c/em\u003e gastrointestinal dynamics of SAPs remain unclear.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe developed a murine model to determine the temporal changes in SAP localization and size following ingestion. The results were compared with the \u003cem\u003ein vitro\u003c/em\u003e behavior of SAPs. Additionally, the effects of the co-administration of water on SAP behavior \u003cem\u003ein vivo\u003c/em\u003e were also assessed.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003e\u003cem\u003eIn vitro\u003c/em\u003e, SAPs rapidly expanded within 1 h, and the extent of expansion was strongly influenced by pH and the composition of the solution. \u003cem\u003eIn vivo\u003c/em\u003e, SAPs enlarged more gradually, reaching maximum size in the cecum approximately 4 h after ingestion and subsequently shrinking during colonic passage until excretion, thereby reducing the risk of intestinal obstruction. Co-administration of water accelerated SAP expansion, delayed gastrointestinal transit, and increased particle size, particularly in the small intestine and cecum, suggesting that dietary and fluid management should be carefully considered in patients with accidental SAP ingestion.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eSAP gradually expanded from the stomach to the small intestine and shrank during expulsion through the colon. The simultaneous administration of water accelerated SAP expansion and delayed gastrointestinal transit.\u003c/p\u003e","manuscriptTitle":"Gastrointestinal dynamics of superabsorbent polymers: Insights from a murine model","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-01 07:44:25","doi":"10.21203/rs.3.rs-8060722/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e884ff4c-2a7a-4595-94a6-192fa57bcd77","owner":[],"postedDate":"December 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-15T01:23:59+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-01 07:44:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8060722","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8060722","identity":"rs-8060722","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}