{"paper_id":"41660360-3609-41fd-9daf-b1f3c39b4a12","body_text":"Fu et al. BMC Women’s Health          (2023) 23:240  \nhttps://doi.org/10.1186/s12905-023-02404-1\nRESEARCH Open Access\n© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which \npermits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the \noriginal author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or \nother third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line \nto the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory \nregulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. 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The Creative Commons Public Domain Dedication waiver (http:// creat iveco \nmmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.\nBMC Women’s Health\nEffects of spinal anaesthesia and intravenous \ngeneral anaesthesia on the absorption \nof normal salinein patients undergoing \nhysteroscopic endometrial resection: \nan observational study\nWuchang Fu1†, Xue Li2†, Hongchun Xu2†, Ting Zhao3† and Fangjun Wang2* \nAbstract \nIntroduction The absorption of uterine distention fluid during hysteroscopic endometrial resection can cause vol-\numeoverload, which can lead to coagulation dysfunction, acute left heart failure and pulmonary oedema in patients. \nThe effects of spinal anaesthesia and intravenous general anaesthesia on the absorption of normal saline as uterine \ndistention fluid during hysteroscopic surgery remain unclear. The aim of this clinical trial was toobserve the effects of \nspinal anaesthesia and intravenous general anaesthesia on the absorption of normal saline in patients undergoing \nhysteroscopic endometrial resection.\nMethods A total of 126 patients undergoing elective hysteroscopic endometrial resection were divided into a spinal \nanaesthesia group (s group) and a propofol-fentanyl intravenous anaesthesia group (PF group), with 63 cases in each \ngroup, and both groups were divided into a short-term group  (S1 group and  PF1 group) and a long-term group  (S2 \ngroup and  PF2 group) according to the operation time. The primary outcome was the absorption of normal saline, \nand the secondary outcomes included the perioperative SBP , DBP , HR and  SpO2 and postoperative haematocrit val-\nues, and the incidence of postoperative complications.\nResults The volume of saline absorbed was significantly increased in the  S2 and  PF2 groups compared with the  S1 \nand  PF1 groups (P < 0.001). There was a significant positive correlation between the amount of normal saline absorbed \nand the operation time (r = 0.895, P < 0.001). The postoperative haematocrit value was slightly lower than that before \nthe operation in all four groups (P < 0.05), and there were no differences in the incidences of urinary retention, sinus \nbradycardia or hypotension between groups (P > 0.05).\nConclusions There was no difference in the effects of spinal anaesthesia and intravenous general anaesthesia on \nthe absorption of normal saline during hysteroscopic endometrial resection, and the absorption of normal saline \nincreased accordingly with the extension of operation time.\n†Wuchang Fu, Xue Li, Hongchun Xu and Ting Zhao contributed equally to \nthis work.\n*Correspondence:\nFangjun Wang\nwfjlxy006@nsmc.edu.cn\nFull list of author information is available at the end of the article\n\nPage 2 of 9Fu et al. BMC Women’s Health          (2023) 23:240 \nKeywords Spinal anaesthesia, Intravenous general anaesthesia, Absorption, Uterine distention fluid, Hysteroscopic \nendometrial resection\nIntroduction\nHysteroscopic surgery has become a standard surgical \ntreatment for abnormal uterine bleeding that is ineffec -\ntive in conservative treatment, and it has been shown to \nbe a safe and effective alternative to hysterectomy [1]. \nHysteroscopic surgery requires distention of the uterine \ncavity with distention medium to fully display the surgi -\ncal area. However, distention fluid can be absorbed rap -\nidly through the surgical wound and retained in the body \nduring surgery, which can easily lead to fluid overload. \nSevere fluid overload can cause coagulation dysfunction, \nacute left heart failure and pulmonary oedema in patients \nundergoing surgery [2].\nIt was found that different anaesthesia methods had \ndifferent effects on the absorption of glycine as uter -\nine distention fluid during hysteroscopic surgery, but \nthe results were inconsistent [3, 4]. Berg et  al. reported \nthat the mean serum sodium level dropped significantly \nin a monopolar resectoscope using 1.5% glycine with no \nchange in the bipolar resectoscope using 0.9% saline [5], \nsuggesting that bipolar resectoscopes with 0.9% normal \nsaline have a better safety profile. At present, the effects \nof spinal anaesthesia and intravenous general anaesthesia \non the absorption of normal saline during hysteroscopic \nsurgery are unclear. Our objective was to determine \nwhether spinal anaesthesia and intravenous general \nanaesthesia have different effects on the absorption of \nnormal saline as uterine distention fluid during hystero -\nscopic endometrial resection.\nMethods\nThis observational clinical study was performed from \nFebruary 2022 to August2022, and a total of 126 patients \nwho underwent elective hysteroscopic endometrial \nresection were included in the study. These women, who \nhad previously been treated with various combinations \nof progestin, antifibrinolytic drugs, gonadotropin releas -\ning hormone analogues, nonsteroidal anti-inflammatory \ndrugs, and oral contraceptives, underwent endome -\ntrial resection due to symptomatic menorrhagia. The \ninclusion criteria for this study were American Soci -\nety of Anaesthesiologists (ASA) classification I or II, \n18.5 ≤ BMI ≤ 24  kg/m2, personal consent of the patient \nand age 18 to 60 years. The exclusion criteria were coag -\nulation dysfunction, hypertension, diabetes mellitus, \ndeformity in the spinal anatomyor skin infection on the \nback, history of allergies to local anaesthetics or propo -\nfol, submucosal fibroids, uterine prolapse, endometrial \nhyperplasia, uterine polyps, and cervical or endometrial \nprecancerous lesions. Withdrawal criteria included a \nchange in the surgical plan, refusal by the patient or rela -\ntives to continue the study, and incomplete data collec -\ntion. All patients underwent preoperative transvaginal \npelvic ultrasonography, cervical smear and coagulation \ntests. Patients were grouped according to the anaesthe -\nsia methods. If the patients underwent propofol-fenta -\nnyl intravenous anaesthesia during surgery, they were \nincluded in the propofol-fentanyl intravenous anaesthe -\nsia group (PF group). If the patients underwent spinal \nanaesthesia during surgery, they were included in the \nspinal anaesthesia group (S group), with 63 cases in each \ngroup. According to the operation time, both groups \nwere divided into a short-term group (operation time less \nthan or equal to 30 min)  (S1 group and  PF1 group) and a \nlong-term group (operation time more than 30 min)  (S2 \ngroup and  PF2 group).\nThe patients fasted for 8 h without any preanaesthetic \nmedication. After arriving in the operating room, all \npatients were routinely monitored noninvasively for sys -\ntolic and diastolic blood pressure, electrocardiography, \ncapnography for end-tidal carbon dioxide, pulse oxime -\ntry, and heart rate. After good IV access to the upper \nlimb was secured, Ringer’s lactic acidsolution was used \nfor IV hydration during surgery. In both groups, the \nintravenous fluids were adjusted for fluid maintenance \nrequirements after a bolus of 6 to 8  ml/kg. For patients \nin the spinal anaesthesia group, a spinal neuraxial block \nwas performed at the  L3-4 interspace with ropivacaine \n15.0  mg (mg) by the anaesthesiologist under an aseptic \n technique. For patients in the propofol-fentanyl intrave -\nnous anaesthesia group, general anaesthesia was induced \nwith intravenous administration of midazolam 0.04 mg/\nkg, fentanyl  2 µg/kg, propofol 2  mg/kg and cisatracu -\nrium 0.15  mg/kg. After tracheal intubation, controlled \nmechanical ventilation was adjusted to maintain an end-\ntidal carbon dioxide concentration of 40 to 45  mmHg. \nAnaesthesia was maintained with propofol 4 ~ 6  mg/\nkg•h and fentanyl 2 ug/kg•h to maintain a BIS value of \n40–60 during surgery. All hysteroscopic procedures were \nperformed by an experienced gynaecologic endoscopist \nwith a bipolar resectoscope (Karl Storz SE & Co.KG, Tut-\ntlingen, Germany). Patients were placed in the lithotomy \nposition during the operation, a 0.9% sodium chloride \nsolution was used as the uterine distention medium, and \nan automatic surgical irrigator (Tonglu Jingrui Medi -\ncal Instruments Co., Ltd., Zhejiang, China) was used to \n\nPage 3 of 9\nFu et al. BMC Women’s Health          (2023) 23:240 \n \ncontrol the pressure outflow. The uterine distention fluid \nwas irrigated at a variable flow rate under continuous \npressure of 100  mmHg. Hypotension (defined assystolic \nblood pressure falling more than 20% before anaesthesia \nor systolic blood pressure values lower than 80  mmHg) \nwas immediately treated with an ephedrine 6  mg intra -\nvenous bolus. Bradycardia (defined as a heart rate  < 55 \nbeats/minute) was treated with 0.5  mg of injected \natropine.\nThe primary outcome was the amount of uterine dis -\ntention fluid absorbed in each group during the opera -\ntion. The amount of uterine fluid absorbed was equal \nto the amount of fluid irrigated into the uterine cavity \nminus the amount of fluid that passed through the cer -\nvix into the container bottle and onto the surgical drapes \nand the operating room floor. The amount of uterine dis-\ntention liquid spilled on the floor of the operating room \nwas completely absorbed by the preweighed dry surgical \ndrapes, and then the volume was calculated according to \nthe weight of the liquid absorbed by the surgical drapes \nand the density of normal saline.\nThe blood pressure (SBP and DBP), heart rate and \npulse oxygen saturation of patients in each group were \nrecorded from a Centricity Anaesthesia system and \nelectronic medical records when the patients entered \nthe operation room  (T0), 5 min after anaesthesia induc -\ntion or subarachnoid injection  (T1), at the beginning of \nthe operation  (T2), during the operation  (T3), at the end \nof the operation  (T4), and 3 h after the operation  (T5). A \ntotal of 2 ml of arterial blood samples were collected at \n T0,  T4 and  T5 to measure the arterial blood gas analysis \nand haematocrit (HCT) of patients. For each patient, age, \nbody weight, ASA physical status, uterine size, operation \ntime, and intraoperative and postoperative complications \nsuch as bradycardia, hypotension, nausea and vomiting, \nand urinary retention were recorded from electronic \nmedical records using a standardized form.\nStatistical analysis\nWe calculated that a sample size of 28 patients would be \nneeded in each group (type I error of 0.05, power of 0.9) \nbased on a previous study [6] using PASS 15. Considering a \n20% dropout rate, a total of 135 patients were necessary. The \nfollowing formula was used to compute the sample size:\nWhere  nij represents the sample size of each group, T \nrepresents the number of comparisons between the two \ngroups, and σ 1 and σ 2 represent the standard deviations \nnij =\n(\nZ1−α/(2T ) + Z1−β\n)2 ×\n(\nσ12 + σ22)\nδij 2\nn = max nij , pairs(i, j)\nof Group 1 and Group 2, respectively. δ ij represents the \nvalue of the difference between any two groups with clin-\nical significance. Furthermore, σ was 62 in all groups, μ 1 \nand μ 2 were 100 in the  S1 and  S2 groups, and μ 3 and μ 4 \nwere 145 in the  PF1 and  PF2 groups, respectively.\nData were statistically processed using the SPSS \n24.0program. The results were expressed as the \nmean ± standard deviation (SD) unless otherwise indi -\ncated. One-way analysis of variance (ANOVA) with \nBonferroni’s post hoc test was used to compare mean \ndifferences between groups for demographic data (age, \nweight, and uterine size), the amount of normal saline \nirrigated and absorbed, intraoperative intravenous infu -\nsion volume and urine volume, and operation time. SBP , \nDBP , HR,  SpO2 and HCT were analysed by repeated \nmeasures analysis of variance, and the SNK post hoc test \nwas performed if the comparison between groups was \npositive.  X2 or Fisher’s exact tests were used to compare \ndifferences between groups for ASA physical status clas -\nsification and the incidence of bradycardia, nausea and \nvomiting, hypotension, and urinary retention. A P value \nof < 0.05 was considered statistically significant.\nResults\nA total of 135 patients who underwent thysteroscopic \nendometrial resection were enrolled in this study; three \npatients with hypertension were excluded (one patient \nin the PF group and two patients in the S group), two \npatients in the S group had incomplete data collection, \nand two patients in the PF group cancelled the surgical \nprocedure due to drug allergies. During the operation, \ntwo patients underwent changes in the surgical plan \nbecause of intraoperative uterine perforation. Finally, \nthe data of 126 patients were included. There were 36 \npatients in the S group and 33 patients in the PF group \nwith operation times  ≤ 30  min, so 36, 27, 33, and 30 \npatients in the  S1,  S2,  PF1 and  PF2 groups, respectively, \nwere analysed (Fig.  1). The demographic data of the \npatients in all groups were comparable in regard to age, \nweight, uterine size and ASA physical status classifica -\ntion, as shown in Table 1 (P > 0.05). The volume of normal \nsaline irrigated and absorbed, intraoperative intrave -\nnous infusion volume, urine volume, and operation time \nwere significantly increased in the  S2 and  PF2 groups \ncompared with the  S1 and  PF1 groups ( p < 0.05). The \nabsorption of normal saline was significantly positively \ncorrelated with the operation time ( r = 0.895, P < 0.001) \n(Table  2). After anaesthesia induction or subarachnoid \ninjection, the SBP and DBP values decreased significantly \nin all four groups ( P < 0.05). Although oxygen saturation \nincreased significantly from anaesthesia induction to 3 h \nafter the operation in the  PF1 and  PF2 groups (P < 0.05), it \nwas not clinically significant. The heart rate at  T1~3 was \n\nPage 4 of 9Fu et al. BMC Women’s Health          (2023) 23:240 \nsignificantly decreased in the  PF1 and  PF2 groups com -\npared with the  S1and  S2groups (P < 0.05). There were no \ndifferences in the values of SBP , DBP or  SpO2 between \ngroups at different time points (P > 0.05) (Figs.  2, 3, 4 \nand 5). The haematocrit values decreased significantly \nat the end of the operation (P < 0.05) and returned to \nFig. 1 Study flow diagram\nTable 1 Demographic data\nValues are mean ± SD, number of patients.  S1: spinal anesthesia with operation time ≤ 30 min;  S2: spinal anesthesia with operation time > 30 min;  PF1: propofol-fentanyl \nintravenous anesthesia with operation time ≤ 30 min;  PF2: propofol-fentanyl intravenous anesthesia with operation time > 30 min\nASA American Society of Anesthesiologists\nGroups n Age(y) Weight(kg) ASA(I/II) Uterine size(cm)\nvertical diameter anteroposterior \ndiameter\ntransverse \ndiameter\nS1 36 37.6 ± 4.3 54.7 ± 3.9 22/14 6.8 ± 0.5 3.7 ± 0.3 4.7 ± 0.4\nS2 27 35.8 ± 4.6 56.3 ± 4.2 18/9 6.6 ± 0.3 3.6 ± 0.2 5.0 ± 0.5\nPF1 33 36.6 ± 5.2 54.3 ± 4.3 20/13 6.9 ± 0.5 3.8 ± 0.3 4.9 ± 0.4\nPF2 30 37.2 ± 4.8 55.1 ± 3.7 19/11 6.8 ± 0.4 3.7 ± 0.3 4.8 ± 0.4\nF/x2 values 0.549 0.912 0.875 1.308 1.276 0.779\nP values 0.946 0.437 0.831 0.275 0.286 0.508\n\nPage 5 of 9\nFu et al. BMC Women’s Health          (2023) 23:240 \n \nTable 2 The amount of normal saline irrigated and absorbed, intraoperative intravenous infusion volume, urine volume and operation \ntime\nValues are mean ± SD.  S1: spinal anesthesia with operation time ≤ 30 min;  S2: spinal anesthesia with operation time > 30 min;  PF1: propofol-fentanyl intravenous \nanesthesia with operation time ≤ 30 min;  PF2: propofol-fentanyl intravenous anesthesia with operation time > 30 min\n*p < 0.001 vs.  S1 group, #p < 0.05 vs.  PF1 group\nGroups n Absorption of \nnormal saline(ml)\nIrrigation of normal saline\n(ml)\nIntravenous \ninfusion(ml)\nOperation time(min) Urine volume(ml)\nS1 36 317.8 ± 16.8 4118.6 ± 287.5 428.7 ± 78.3 25.8 ± 1.6 224.8 ± 43.4\nS2 27 415.8 ± 14.7*# 6215.8 ± 496.6*# 514.1 ± 66.4*# 53.6 ± 4.4*# 316.5 ± 48.8*#\nPF1 33 307.2 ± 11.2 4087.2 ± 356.6 436.2 ± 50.0 26.3 ± 2.0 231.4 ± 50..7\nPF2 30 421.2 ± 13.7*# 6186.2 ± 467.9*# 523.6 ± 56.8*# 52.5 ± 5.4*# 323.7 ± 57.7*#\nF values 338.280 171.743 13.177 413.790 24.313\nP values 0.000 0.000 0.000 0.000 0.000\nFig. 2 The values of systolic blood pressure in four groups at different time points\nFig. 3 The values of diastolic blood pressure in four groups at different time points\n\nPage 6 of 9Fu et al. BMC Women’s Health          (2023) 23:240 \nalmost baseline levels3 h after the operation in all four \ngroups. There were no differences in the haematocrit \nvalues between groups at different time points (P > 0.05) \n(Table  3). The incidence of postoperative nausea and \nvomiting was higher in the  PF1and  PF2groups than in the \n S1 and  S2 groups (P < 0.05). There was no difference in the \nFig. 4 The values of heart rate in four groups at different time points\nFig. 5 The values of pulse oxygen saturation in four groups at different time points\nTable 3 The values of hematocrit at different time points\nValues are mean ± SD.  T0: before operation;  T4: the end of operation;  T5: 3 h after operation.  S1: spinal anesthesia with operation time ≤ 30 min;  S2: spinal anesthesia \nwith operation time > 30 min;  PF1: propofol-fentanyl intravenous anesthesia with operation time ≤ 30 min;  PF2: propofol-fentanyl intravenous anesthesia with \noperation time > 30 min\n* P < 0.05 vs.  T0\nGroups n T0 T4 T5 F values P values\nS1 36 39.6 ± 2.4 35.8 ± 1.9* 38.6 ± 2.3 15.808 0.000\nS2 27 38.5. ± 2.3 34.9 ± 2.0* 37.6 ± 2.4 11.541 0.000\nPF1 33 39.0 ± 2.6 35.2 ± 1.8* 38.1 ± 2.3 15.624 0.000\nPF2 30 38.8 ± 2.8 36.1 ± 2.4* 37.9 ± 2.5 4.626 0.012\nF values 0.556 1.174 0.429 - -\nP values 0.645 0.323 0.733 - -\n\nPage 7 of 9\nFu et al. BMC Women’s Health          (2023) 23:240 \n \nincidence of intraoperative or postoperative bradycardia \nor hypotension (P > 0.05). There were two patients with \npostoperative urinary retention in the  S1  and  S2  groups \nand none in the  PF1 and  PF2 groups (Table 4).\nDiscussion\nIn our study, there was no difference in the absorption \nof uterine distention fluid during hysteroscopic endome -\ntrial resection using normal saline as the uterine disten -\ntion fluid between patients undergoing spinal anaesthesia \nand those with intravenous general anaesthesia. With the \nextension of operation time, the absorption of uterine \ndistention fluid in patients undergoing spinal anaesthesia \nor intravenous general anaesthesia increased accordingly. \nThe perioperative haemodynamics in patients during \nspinal anaesthesia and general anaesthesia were stable. \nThe incidence of postoperativenausea and vomiting was \nhigher in patients with intravenous anaesthesia than in \nthose with spinal anaesthesia.\nBecause of its low trauma, short operation time and \nrapid postoperative recovery, hysteroscopic surgery is \nwidely used in the clinic [7]. Different dilatation media \nare often selected according to the electrodes used in \nthe operation. Fluid overload caused by the absorption \nof uterineirrigation fluid is the main source of compli -\ncations during hysteroscopic procedures [8]. At pre -\nsent, there are few studies on the absorption of uterine \ndistention fluid during hysteroscopic surgery. A clini -\ncal studyshowed thatthe amount of glycine absorbed \nwith epidural anaesthesia (648.3 ± 157.1  ml) was sig -\nnificantly higher than that with intravenous anaesthesia \n(380.8 ± 158.2  ml) during endometrial resection. This is \nmainly due to the expansion of peripheral blood vessels \nduring epidural block, which is more likely to promote \nthe absorption of glycine [3]. Bergeron et al. reported that \nthe absorption of glycine under cervical local block com -\nbined with intravenous sedation in endometrial resection \n(33 ~ 45 ml) was significantly lower than that under intra-\nvenous anaesthesia (125 ~ 300 ml). The relaxation of arte-\nriole muscles under general anaesthesia may result in the \nexpansion of systemic arterial blood vessels and acceler -\nate the absorption of glycine [9]. Darwish AM et al. found \nthat there was no difference in the absorbed fluid vol -\numes of glycine and normal saline during hysteroscopic \nmyomectomy under general anesthesia [10]. It was sug -\ngested that different anaesthesia had significant effects \non the absorption of uterine distention fluid during hyst -\neroscopic surgery, while different dilatation media had no \neffects on the absorption of uterine dilatation fluid. In our \nstudy, we found that there was no difference in the effects \nof spinal anaesthesia and intravenous general anaesthe -\nsia on the absorption of normal saline as uterine disten -\ntion fluid in either the short-term group or the long-term \ngroup, which was inconsistent with the above research \nconclusions. The reason for this inconsistency may be \nthat the body’s blood vessels were expanded under spi -\nnal anaesthesia and general anaesthesia [9], which may \nhave the same effect on the absorption of normal saline \nduring hysteroscopic endometrial resection. In our study, \nthe absorption of normal saline under spinal anaesthesia \nand intravenous anaesthesia was significantly increased \nin the long-term group compared with the short-term \ngroup. This result indicated that the absorption of dis -\ntention fluid increasedaccordingly with the extension of \noperation time [11]. Therefore, the absorption of uterine \ndilatation fluid should be monitored during long-term \nhysteroscopic surgery to avoid fluid overload [12].\nThe clinical study found that the amount of glycine \nabsorbed under spinal anaesthesia combined with oxy -\ntocin infusion in hysteroscopic surgery was signifi -\ncantly less than that under intravenous anaesthesia, but \nthe MAP of the two groups was 87.0 ± 10.0  mmHg and \n87.8 ± 12.7 mmHg (P > 0.05), indicating that there was no \ndifference in blood pressure between the two groups [6]. \nIn the present study, we also found that there was no dif -\nference in SBP or DBP between groups at different times, \nand the incidence of hypotension and bradycardia was \nsimilar among all groups. It was suggested that there was \nalmost no difference in the effect of general anaesthesia \nand spinal anaesthesia on the blood pressure of patients \nduring hysteroscopic surgery, regardless of the different \nabsorption of glycine or the same absorption of normal \nsaline. The main reason for this result is that the differ -\nence in the absorption of glycine between the two groups \nwas only approximately 560 ml in previous studies [13]. \nMost of the hypotonic glycine solution absorbed into the \nvascular system was quickly transferred into the tissue \nand cells in the body, and the amount of glycine left in \nTable 4 Intraoperative and postoperative bradycardia and \nhypotension, and postoperative nausea and vomiting and \nurinary retention\nValues are number of patients.  S1: spinal anesthesia with operation \ntime ≤ 30min;  S2: spinal anesthesia with operation time > 30 min;  PF1: propofol-\nfentanyl intravenous anesthesia with operation time ≤ 30min;  PF2: propofol-\nfentanyl intravenous anesthesia with operation time > 30 min\nGroups n Nausea \nand \nvomiting\nBradycardia Hypotension Urinary \nretention\nS1 36 3 6 4 2\nS2 27 3 4 3 2\nPF1 33 7 5 5 0\nPF2 30 7 6 4 0\nX2 values 3.896 0.361 0.333 4.303\nP values 0.043 0.948 0.954 0.231\n\nPage 8 of 9Fu et al. BMC Women’s Health          (2023) 23:240 \nthe circulatory system was relatively small, which had lit -\ntle effect on the circulation. In our study, the absorption \nof normal saline during spinal anaesthesia and intrave -\nnous anaesthesia was similar, so the effect of the absorp -\ntion of uterine dilatation fluid on circulation was also \nthe same in both types of anaesthesia. The absorption \nof uterine dilatation fluid was primarily studied in the \npresent study, while changes in blood pressure were less \nfrequently observed during hysteroscopic surgery. The \noperation time was within 60 min in our study, and the \neffects of the absorption of normal saline on blood pres -\nsure in long-term hysteroscopic surgery under different \ntypes of anaesthesia were not clear.\nA previous study showed that the haematocrit was \ndecreased slightly after hysteroscopic surgery [2]. In this \nstudy, the haematocrit of patients after surgery was also \nslightly lower than that before the operation, but the \nhaematocrit returned to the preoperative level 3  h after \nthe operation. This result indicated that the absorption of \nuterine dilatation fluid during hysteroscopic surgery had \nlittle effect on the haematocrit and that the haematocrit \nrecovered rapidly after surgery. There was no difference \nin the incidence of postoperative nausea and vomit -\ning between the long-term group and short-term group \nunder spinal anaesthesia or intravenous general anaes -\nthesia. However, the incidence of postoperative nausea \nand vomiting during spinal anaesthesia was 9.5%, while \nthat during intravenous general anaesthesia was 20.6%, \nwhich showed that the time of hysteroscopic surgery had \nno effect on postoperative nausea and vomiting, while \nthe different types of anaesthesia had a significant effect \non postoperative nausea and vomiting [14].\nThere were several limitations in our study. First, the \namount of uterine distention fluid that evaporated dur -\ning the operation was not included in this study. Because \nall of the patients included in the study were in the same \noperating room with the same temperature and humid -\nity, the amount of uterine distention fluid lost during the \noperation due to evaporation should be consistent for \neach patient. Second, in our preliminary study, we found \nthat the hysteroscopic surgery time of approximately \nhalf of the patients was less than 30  min. Therefore, \nall patients were divided into a long-term group and a \nshort-term group according to operation times less than \nor equal to 30 min and more than 30 min in the S group \nand PF group, respectively. The time of hysteroscopic \nsurgery in this study was within 60  min. The effects \nof spinal anaesthesia and general anaesthesia on the \nabsorption of uterine distention fluid in long-term hys -\nteroscopic surgery remain unclear and need to be stud -\nied in the future. Third, the absorption of no electrolytic \nsolution in transurethral prostatectomy damaged the \ncascade of blood coagulation, resulting in the inhibition \nof coagulation factor activity or the reduction of coagu -\nlation factor concentration through blood haemodilu -\ntion. In this study, changes in the coagulation system \nwere not studied, but no patients had coagulation dys -\nfunction during or after the operation. The absorption \nof normal saline under intravenous anaesthesia and spi -\nnal anaesthesia had no significant effect on coagulation \nfunction in patients undergoing hysteroscopic endome -\ntrial resection. Fourth, the administration of oxytocin \nduring hysteroscopic surgery can significantly reduce \nthe absorption of uterine distention fluid [14, 15]. In \nour study, oxytocin was not administered during hyst -\neroscopic endometrial resection. Because of the short \noperation time and low absorption of uterine distention \nfluid, the patients in this study did not have correspond -\ning complications. Considering that the absorption of \nuterine dilatation fluid was significantly related to the \nduration of hysteroscopic surgery, oxytocin should be \nadministered appropriately in clinical practice to reduce \nthe absorption of uterine dilatation fluid and avoid the \ncorresponding complications of fluid overload.\nIn conclusion,  there was no difference in the effect \nof spinal anaesthesia and intravenous general anaes -\nthesia on the absorption of normal saline during hyst -\neroscopic endometrial resection, and the absorption of \nnormal saline increased accordingly with the extension \nof operation time.\nAcknowledgements\nThe authors thank the participants for their enthusiastic collaboration, the \nlaboratory physician of the Affiliated Hospital of North Sichuan Medical Col-\nlege who helped test the haematocrit, and the gynaecological surgeons and \nnurses who assisted with specimen collection.\nAuthors’ contributions\nWC.F. and FJ.W. designed and supervised the clinic study, WC.F., X.L. and HC.X. \nanalysed and interpreted the data. X.L. and T.Z. performed clinical data acquisi-\ntion. HC.X. and T.Z. processed all the samples and detected the hematocrit. \nWC.F., T.Z. and FJ.W. wrote the manuscript. All authors contributed to discuss \nthe results and to research directions. All authors approved the manuscript.\nFunding\nThis work was supported by the Sichuan Provincial Health Commission (2017, \n17PJ215).\nAvailability of data and materials\nThe datasets used and/or analysed during the current study are available from \nthe corresponding author upon reasonable request. Due to ethical reasons, to \nprotect the integrity of the participants, the study data are not publicly available.\nDeclarations\nEthics approval and consent to participate\nThis observational clinical study was approved by the ethics committee of Nan-\nchong Central Hospital Affiliated to North Sichuan Medical College (IRB2022.002) \nand registered with the Chinese Clinical Trial Registry (http:// www. chictr. org. cn/; \nPrincipal investigator: Wuchang Fu, Date of registration: 09/02/2022, Registration \nnumber: ChiCTR2200056605) prior to patient enrolment. All procedures per-\nformed in this study followed ethical standards of research and the Declaration of \nHelsinki. Participants received oral and written information about the observa-\ntional study prior to inclusion and signed informed consent.\n\nPage 9 of 9\nFu et al. BMC Women’s Health          (2023) 23:240 \n \n•\n \nfast, convenient online submission\n •\n  \nthorough peer review by experienced researchers in your field\n• \n \nrapid publication on acceptance\n• \n \nsupport for research data, including large and complex data types\n•\n  \ngold Open Access which fosters wider collaboration and increased citations \n \nmaximum visibility for your research: over 100M website views per year •\n  At BMC, research is always in progress.\nLearn more biomedcentral.com/submissions\nReady to submit y our researc hReady to submit y our researc h  ?  Choose BMC and benefit fr om: ?  Choose BMC and benefit fr om: \nConsent for publication\nNot applicable.\nCompeting interests\nThe authors declare no competing interests.\nAuthor details\n1 From the Second Clinical Medical College of North Sichuan Medical College \n(Nanchong Central Hospital), Nanchong 637000, China. 2 From the Affiliated \nHospital, North Sichuan Medical College, Nanchong 637000, China. 3 From \nNorth Sichuan Medical College, Nanchong 637000, China. \nReceived: 19 January 2023   Accepted: 30 April 2023\nReferences\n 1. Masciullo V, Trivellizzi N, Zannoni G, Catena U, Moroni R, Fanfani F, et al. \nPrognostic impact of hysteroscopic resection of endometrial atypical \nhyperplasia-endometrioid intraepithelial neoplasia and early-stage \ncancer in combination with megestrol acetate. Am J Obstet Gynecol. \n2021;224(4):408–10. https:// doi. org/ 10. 1016/j. ajog. 2020. 12. 1210.\n 2. Shin HJ, Na HS, Han JY, Hwang JW. 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Best Pract Res Clin Obstet Gynaecol. 2015;29(7):982–93. \nhttps:// doi. org/ 10. 1016/j. bpobg yn. 2015. 03. 009.\nPublisher’s Note\nSpringer Nature remains neutral with regard to jurisdictional claims in pub-\nlished maps and institutional affiliations.","source_license":"CC0","license_restricted":false}