{"paper_id":"1a22bbbd-73ba-468d-a540-68a486706b30","body_text":"Chen et al. BMC Pregnancy and Childbirth          (2022) 22:187  \nhttps://doi.org/10.1186/s12884-022-04529-x\nRESEARCH\nAssociation between the occurrence \nof adenomyosis and the clinical outcomes \nof vaginal repair of cesarean section scar \ndefects: an observational study\nHuihui Chen1†, Wenjing Wang2†, Husheng Wang1*† and Xipeng Wang1*† \nAbstract \nBackground: To examine the correlation between the occurrence of adenomyosis and the outcome of vaginal repair \nof cesarean section scar defects (CSDs).\nMethods: A total of 278 women with CSD were enrolled in this retrospective observational cohort study at the \nShanghai First Maternity & Infant Hospital between January 2013 and August 2017. Patients were divided into two \ngroups according to preoperative magnetic resonance imaging (MRI) findings: the adenomyosis group and the \nnon-adenomyosis group. They all underwent vaginal excision and suturing of CSDs and were required to undergo \nexaminations 3 and 6 months after surgery. Preoperative and postoperative clinical information was collected. Opti-\nmal healing was defined as a duration of menstruation of no more than 7 days and a thickness of the residual myome-\ntrium (TRM) of no less than 5.8 mm after vaginal repair.\nResults: Before vaginal repair, for patients in the adenomyosis group, the mean duration of menstruation was longer \nand TRM was significantly thinner than those in patients in the non-adenomyosis group (p < 0.05). The TRM and \nduration of menstruation 3 and 6 months after surgery were significantly improved in both groups (p < 0.05). There \nwere more patients with optimal healing in the non-adenomyosis group than in the adenomyosis group (44.7% \nvs. 30.0%; p < 0.05). Furthermore, 59.3% (32/54) of the women tried to conceive after vaginal repair. The pregnancy \nrates of women with and without adenomyosis were 66.7% (8/12) and 61.9% (26/42), respectively. The duration of \nmenstruation decreased significantly from 13.4 ± 3.3 days before vaginal repair to 7.6 ± 2.3 days after vaginal repair in \n25 patients (p < 0.001). The TRM increased significantly from 2.3 ± 0.8 mm before vaginal repair to 7.6 ± 2.9 mm after \nvaginal repair (p < 0.001).\n© The Author(s) 2022. 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. To view a copy of this \nlicence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. 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.\nOpen Access\n*Correspondence:  wanghusheng@xinhuamed.com.cn; \nwangxipeng@xinhuamed.com.cn\n†Huihui Chen and Wenjing Wang contributed equally to this work and \nshould be considered co-first authors.\n†Husheng Wang and Xipeng Wang contributed equally to this work and \nshould be considered co- corresponding authors\n1 Department of Obstetrics and Gynecology, Xin Hua Hospital affiliated \nto Shanghai Jiao Tong University School of Medicine, 1665 Kong Jiang \nRoad, Yangpu District, Shanghai 200092, China\nFull list of author information is available at the end of the article\n\nPage 2 of 11Chen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \nIntroduction\nThe World Health Organization (WHO) suggested that \nthe rate of cesarean sections be maintained at 15% [1]. \nHowever, in China, the rate of cesarean section increased \nfrom 28.8% in 2008 to 34.9% in 2014, and in 2018 reached \n36.7% [2]. With the increase in the number of cesar -\nean sections, cesarean section scar defects (CSDs), as a \nnew type of iatrogenic disease, have gained enormous \nresearch momentum. CSDs were first described by Mor -\nris in 1995 as a pouch-like defect in the anterior uterine \nwall at the site of a previous cesarean section [3]. Many \npatients with CSD are asymptomatic; however, many \nhave reported intermenstrual spotting, dysmenorrhea, \ndyspareunia, and chronic pelvic pain. Other studies have \nreported that CSD is an adverse factor for uterine rup -\nture and infertility [4–7].\nMagnetic resonance imaging (MRI) and transvaginal \nsonography (TVS) are useful in the diagnosis of CSD, \nand both methods can determine the length, width, and \ndepth of the defect and the thickness of the residual myo-\nmetrium (TRM). In addition, MRI is useful in diagnosing \nother gynecological diseases such as fibroids, adenomyo -\nsis, ovarian tumors, and pelvic diseases.\nAdenomyosis, as one of the manifestations of endo -\nmetriosis that affects women of child-bearing age, is cat -\negorized by the presence of hypertrophic smooth muscle \nderived from ectopic endometrial glands and stroma \nwithin the myometrium [8, 9].\nVaginal repair due to CSDs is a minimally invasive and \neffective method that maintains fertility [10–12]. Patients \nsuffering from intermittent postmenstrual bleeding \nwho underwent vaginal repair still had CSDs, although \nthe size of the defect and the clinical symptoms were \nimproved significantly. In another study, adenomyosis \nwas reported to involve repeated autotraumatization and \nself-healing of the endometrial-myometrial junctional \nzone, thereby affecting myometrium healing [13]. This \nprompted us to examine the factors involved in the less-\nthan-optimal outcome of vaginal repair.\nHere, we hypothesized that adenomyosis might be \nan adverse factor for uterine repair. We retrospectively \nreviewed the MRI findings of patients with CSDs to \ndetermine whether there is a correlation between the \noccurrence of adenomyosis and the outcomes of vaginal \nrepair. We also provide clinical recommendations for the \ntreatment of CSDs.\nPatients and methods\nThis retrospective study was approved by the Ethics \nCommittee of the Shanghai First Maternity & Infant \nHospital (KS1512). We retrieved data by diagnostic \ncodes from outpatients with CSDs who underwent MRI \nto determine the length, width, and depth of the defect \nand subsequent vaginal surgery at the Tongji University-\naffiliated Shanghai First Maternity & Infant Hospital \nfrom January 2013 to August 2017. All MRI scans were \nre-evaluated by an experienced radiologist. After educat -\ning the patients on the advantages and disadvantages of \nvaginal surgery, they provided written informed consent. \nAccording to the findings of preoperative MRI scans, the \npatients were divided into two groups: the adenomyosis \ngroup and the non-adenomyosis group.\nThe inclusion criteria were nonpregnant patients who \nhad one or more cesarean sections, patients who had \nintermenstrual spotting after cesarean section, patients \nin which the TRM was less than 3.0 mm at the preopera-\ntive stage, and patients who underwent MRI and TVS to \nevaluate the size of the defect and TRM before surgery \n[14] (Fig.  1). All patients had no serious medical prob -\nlems (important visceral function in the normal range). \nPatients who had a history of chronic diseases (such as \ncerebrocardiovascular diseases, malignancies and dia -\nbetes mellitus), endocrine disorders, menstrual irregu -\nlarities before cesarean section, coagulation disorders, \nintrauterine device use, submucous myoma, endometrial \ndiseases, endometrial cysts, uterine fibroids, or adeno -\nmyosis after cesarean section were excluded from this \nstudy (Fig. 2).\nSurgical procedures\nAll surgical procedures were performed by an expe -\nrienced surgeon as previously described [10, 11, 15]. \nAfter administering continuous epidural anaesthesia, \nthe patients were placed in the bladder lithotomy posi -\ntion. All patients had empty bladders. The anterior peri -\ntoneal reflection was opened, and the abdominal cavity \nwas entered. After exposing the lower uterine segment, a \nprobe was used to identify the CSD area. The tissue was \ntrimmed with scissors to reveal the healthy myometrium, \nand the CSD tissue was completely removed. The myo -\nmetrium was closed using a double-layer closure of 1–0 \nabsorbable sutures with an interrupted suture (Fig. 3).\nConclusions: Vaginal repair reduced postmenstrual spotting and may have improved fertility in patients with CSDs. \nPatients with adenomyosis are more likely to have suboptimal menstruation and suboptimal healing of CSDs. Adeno-\nmyosis might be an adverse factor in the repair of uterine incisions.\nKeywords: Adenomyosis, Cesarean section, Menstrual disorders, Surgery\n\nPage 3 of 11\nChen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \n \nMagnetic resonance imaging\nMRI scans were conducted with a 1.5 T MR scanner \n(Optima MR360; General Electric Company, USA). The \npatients underwent routine screening of the pelvic sagit -\ntal and coronal planes and the fat-suppressed sagittal and \ncoronal planes. All images were evaluated by an experi -\nenced radiologist. Several baseline characteristics were \nassessed on T2-weighted images, including the position \nof the uterus (anteverted or retroverted), the diameter \nof the CSD (the length, width, and depth), the TRM, and \nthe presence of adenomyosis, endometriosis, or uterine \nfibroids.\nThe main features of adenomyosis were an increased \nthickness of the junctional zone of the uterus (exceeding \n12 mm) and the presence of intramyometrial cyst(s) or a \nheterogeneous myometrium, which were associated with \nheterogeneously hyperintense regions on T2-weighted \nand sometimes T1-weighted images (Fig. 4).\nData collection and follow‑up\nData were identified using the diagnostic codes (N85.814) \nin billing records. Preoperative and postoperative clinical \ninformation was collected from medical files, including \nthe following: age; other general patient details; number \nof cesarean sections; history of menstrual conditions; \nposition of the uterus; hemoglobin level on the first post -\noperative day; length of hospitalization; hospitalization \ncost; CSD length, width, and depth; and the TRM. All \npatients were required to undergo examinations 3 and \n6 months after surgery to obtain information on men -\nstruation and to measure anatomical data after surgery \n(the TRM) based on MRI or TVS. Patients who failed to \nFig. 1 MRI images of cesarean scar defects. A. Sagittal view on T2 images. B. Coronal view on T2 images\n\nPage 4 of 11Chen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \nreturn in a timely manner were followed-up by telephone \nand reminded to complete the measure as soon as possi -\nble. Long-term follow-up was conducted in patients with \nsubsequent pregnancy attempts. Data on gestational age, \nneonatal birth weight, infant Apgar score and pregnancy \ncomplications were collected from the patients by tele -\nphone and medical records. Optimal healing was defined \nas a duration of menstruation of no more than 7 days and \na TRM of no less than 5.8 mm after vaginal repair [16].\nStatistical analysis\nSPSS 22.0 software (SPSS Inc., Chicago, IL, USA) was \nused for all statistical analyses. Data are presented as \nthe means ± SD or percentages as appropriate. A paired \nt-test was used to analyze the preoperative and postop -\nerative data. Continuous data are presented as medians \nand ranges, and categorical data are presented as fre -\nquencies and percentages. The hospitalization length \nand cost were analyzed using the Mann-Whitney U \ntest. Categorical variables were analyzed using the chi-\nsquared test or Fisher’s exact test when the number of \nvariables was less than five. P-values < 0.05 were consid -\nered to be statistically significant.\nResults\nPatient characteristics\nThe pre-treatment demographic data are summarized in \nTable 1. Data from a total of 331 patients were retrieved \nin this study. Fifty-three patients were excluded. Twenty-\nthree patients were lost to follow-up, eleven patients had \nendometrial diseases, six patients had endocrine disor -\nders, five patients had uterine fibroids, four patients had \nendometrial cysts, two patients had intrauterine devices \nand two patients had adenomyosis after cesarean sec -\ntion. In total, 278 patients were enrolled and divided \ninto the adenomyosis group (n  = 50), in which the mean \npatient age was 32.6 ± 3.8 years, and the non-adenomyo -\nsis group (n  = 228), in which the mean patient age was \nFig. 2 Flow chart of study\n\nPage 5 of 11\nChen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \n \n32.8 ± 3.6 years (Fig.  2). No significant differences were \nobserved between the groups in the number of cesar -\nean sections, the duration of postmenstrual spotting \nbefore cesarean section, the mean preoperative CSD \nlength, width, and depth, or the TRM measured by TVS \n(p > 0.05). However, the duration of postmenstrual spot -\nting after cesarean section in the adenomyosis group was \nsignificantly longer than that in the non-adenomyosis \ngroup (15.3 ± 4.1 days versus 14.0 ± 3.2 days, p  < 0.05). \nIn addition, the mean preoperative width was signifi -\ncantly longer and the TRM was thicker in the adeno -\nmyosis group than that in the non-adenomyosis group \n(15.0 ± 3.7 mm versus16.6 ± 4.4 mm; 2.9 ± 1.1 mm versus \n2.5 ± 1.2 mm, p < 0.05).\nClinical outcomes after surgery\nAll patients underwent vaginal repair. The clinical data \nare summarized in Table  2. No significant differences in \nthe duration of the surgical procedure, hospitalization \nstay, or hospitalization cost were observed between the \ngroups (p > 0.05). In addition, four out of the 228 patients \nin the non-adenomyosis group had complications (two \ncases of bladder injury and two cases of hematoma), \nwhereas one out of the 50 patients in the adenomyosis \ngroup had a complication (hematoma). Thus, the inci -\ndence of perioperative complications was 1.8 and 2.0% in \nthe two groups, respectively.\nGynecological follow‑up\nData on the duration of menstruation and the TRM \nbefore and after surgery are summarized in Table  3. The \nmean durations of menstruation and TRM of all the \npatients were significantly improved than those before \nsurgery (p  < 0.05). Similarly, for the non-adenomyosis \ngroup, the mean durations of menstruation at the 3- and \n6-month follow-ups were significantly shorter than those \nbefore surgery (8.1 ± 2.5 days and 8.3 ± 2.4 days, respec-\ntively, p  < 0.05). For the adenomyosis group, the mean \ndurations of menstruation at the 3- and 6-month follow-\nups were significantly shorter than those before surgery \nFig. 3 Transvaginal surgery procedure. A. The opening of the anterior peritoneal reflection; B, the trimming of the CSD edge; C, the closing of the \nmyometrium; and D, the end of the procedure\n\nPage 6 of 11Chen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \n(p < 0.05). The TRM at the median-month follow-up was \nsignificantly strengthened in both groups (p < 0.05).\nData on the durations of menstruation at the 3- and \n6-month follow-ups are summarized in Table 4. At the 3- \nand 6-month follow-ups, the mean durations of menstru-\nation were 8.1 ± 2.3 days and 8.1 ± 1.6 days, respectively, \nand no significant difference was observed between \nthe two groups (p  > 0.05). Subsequently, we considered \n7 days as the mean duration of menstruation and divided \nthe patients into two subgroups. We found that 55.3% \n(126/228) of the patients in the non-adenomyosis group \nhad an optimal duration of menstruation (≤7 days) at the \n3- and 6-month follow-ups compared to 38.0% (19/50) of \nthe patients in the adenomyosis group (p  < 0.05). Opti -\nmal healing was more prevalent in the non-adenomyosis \ngroup than in the adenomyosis group (44.7% vs. 30.0%; \np < 0.05).\nPregnancy follow‑up\nThe pregnancy outcome was assessed in 32 out of 54 \nwomen (59.3%) who attempted to conceive after vagi -\nnal repair (Fig.  5). Among these, there were 12 cases of \nadenomyosis and 42 cases of non-adenomyosis. For those \nwho achieved pregnancy, the pregnancy rates of women \nwith and without adenomyosis were 66.7% (8/12) and \n57.1% (24/42), respectively. The data for 25 women (six \nwith adenomyosis and 19 without adenomyosis) who \nachieved pregnancy and delivered infants are summa -\nrized in Table 5. By TVS, the TRM increased significantly \nfrom 2.3 ± 0.8 mm (range, 0.5–4.0 mm) to 7.6 ± 2.9 mm \nFig. 4 MRI scans of cesarean scar defects with adenomyosis. A. Sagittal view on T2 images (retroflexed uterus). B Sagittal view on T2 images \n(anteflexed uterus)\n\nPage 7 of 11\nChen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \n \n(range, 3.0–12.0 mm) at the 3-month follow-up after \nvaginal repair(p  < 0.001). The duration of menstrua -\ntion decreased significantly from 13.4 ± 3.3 days to \n7.6 ± 2.3 days after vaginal repair (p < 0.001). All women \nselected cesarean section as the method of childbirth, \nand there were no cases of uterine rupture or dehiscence.\nDiscussion\nResults from our study showed that vaginal repair is a \nminimally invasive and effective method that maintains \nfertility in patients with CSD [10, 15, 17]. A total of 278 \npatients underwent pre- and postoperative MRI or TVS. \nWe found that gynecological symptoms, such as post -\nmenstrual spotting, and uterine morphology improved \n(Table 3). We also found that patients with adenomyosis \nwere more likely to have suboptimal menstruation and \nsuboptimal healing of CSDs. Adenomyosis might be an \nadverse factor in the repair of uterine incisions. To the \nbest of our knowledge, the results regarding the asso -\nciation between the occurrence of adenomyosis and the \nclinical outcomes of vaginal repair of CSDs in nonpreg -\nnant women have not been published previously.\nTable 1 Patient baseline characteristics prior to treatment\nData presented as mean ± SD (range) except for uterus position. Data presented as numbers (percentage) for uterus position\nCS caesarean section, CSD cesarean scar defect, TRM thickness of the residual myometrium, TVS transvaginal sonography\nDemographic Adenomyosis group(n = 50) Non‑adenomyosis group \n(n = 228)\nP value\nAge (y) 32.6 ± 3.8 (23–41) 32.8 ± 3.6 (23–42) 0.735\nGravidity (n) 2.2 ± 1.1 (1–5) 2.0 ± 1.1 (1–6) 0.175\nNumber of cesarean deliveries (n) 1.4 ± 0.5 (1–3) 1.3 ± 0.5 (1–3) 0.089\nDuration of menstruation before cesarean delivery (d) 6.3 ± 1.3 (3–10) 6.2 ± 1.1 (3–9) 0.793\nDuration of postmenstrual spotting after cesarean delivery (prior \nto surgical repair of CSD) (d)\n15.3 ± 4.1 (5–25) 14.0 ± 3.2 (5–30) 0.013\nUterus position\n anteflexion 25 (50.0%) 99 (43.4%) 0.244\n retroflexion 25 (50.0%) 129 (56.6%)\nTVS findings (mm)\n CSD length 7.7 ± 3.3 (2.0–17.0) 8.0 ± 3.5 (2.0–18.0) 0.640\n CSD width 12.2 ± 4.4 (3.0–23.0) 12.3 ± 5.7 (3.0–30.0) 0.911\n CSD depth 7.1 ± 3.4 (2.0–19.0) 6.4 ± 2.8 (2.0–18.0) 0.177\n TRM 2.9 ± 1.4 (1.0–9.0) 2.7 ± 1.1 (0.7–7.0) 0.253\nMRI findings (mm)\n CSD length 9.3 ± 3.8 (1.0–18.5) 9.1 ± 3.2 (1.0–20.0) 0.653\n CSD width 15.0 ± 3.7 (5.0–22.4) 16.6 ± 4.4 (5.0–28.4) 0.018\n CSD depth 6.0 ± 2.0 (2.5–11.3) 6.2 ± 2.6 (1.6–21.0) 0.619\n TRM 2.9 ± 1.1 (1.0–6.0) 2.5 ± 1.2 (0.5–10.1) 0.033\nTable 2 Clinical outcomes after treatment for cesarean scar defect\nData presented as mean ± SD (range) except for complications, length of hospital stay and hospitalization cost, where complications presented as numbers \n(percentage) and length of hospital stay and hospitalization cost presented as median (interquartile range)\n* Fisher’s Exact Test was used. ** Mann-Whitney U Test was used\nVariable Adenomyosis group (n = 50) Non‑adenomyosis group (n = 228) P value\nHemoglobin on the first postoperative day (g/L) 99.5 ± 13.4 (74.2–125.0) 106.0 ± 11.2 (77.2–134.0) 0.012\nBlood loss during operation (ml) 31.8 ± 20.0 (10–100) 30.8 ± 23.6 (10–200) 0.745\nDuration of surgical procedure (min) 57.0 ± 11.8 (30–90) 55.9 ± 9.4 (25–99) 0.497\nLength of hospital stay (d) 7.0 (1.0) 6.5 (1.0) 0.296**\nHospitalization cost (CNY) 10,870 (2175.3) 11,085.0(1997.3) 0.528**\nComplications (n)\n Bladder injury 0 (0.0%) 2 (.9%) 0.672*\n Hematoma 1 (2.0%) 2 (.9%) 0.450*\n\nPage 8 of 11Chen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \nAdenomyosis is a common gynecological disease char -\nacterized by the infiltration of ectopic endometrial glands \nand/or stroma into the myometrium, thereby causing \ndysmenorrhea, pelvic pain, abnormal uterine bleed -\ning, and infertility [8, 18, 19]. Fifty out of 278 patients \n(18.0%) had adenomyosis, which is consistent with previ -\nous studies reporting an incidence of 20% [20, 21]. The \nmean preoperative CSD width was smaller and the TRM \nwas thicker in patients with adenomyosis than in patients \nwithout the disorder and this was due to the presence of \nhyperplastic and hypertrophic smooth muscle.\nThe duration of menstruation before cesarean section \nwas longer in patients with adenomyosis than that in \npatients without the disorder; however, the results were \nnot significantly different (p  > 0.05). These patients suf -\nfered abnormal uterine bleeding after cesarean delivery. \nIn addition, the duration of menstruation after cesarean \nsection was significantly longer in patients with adeno -\nmyosis than in patients without the disorder (p  < 0.05), \nsuggesting that adenomyosis might disrupt the tissue \nrepair process after cesarean section. In addition, after \nvaginal repair, CSD patients with adenomyosis had a \nmore unfavorable prognosis. At follow-up, the duration \nof menstruation was optimal in patients with adenomy -\nosis (p < 0.05). Furthermore, the optimal rate of optimal \nhealing after vaginal repair was not achieved in patients \nwith adenomyosis (Table 4), suggesting that adenomyosis \nwas an adverse factor in the healing of uterine incisions.\nEctopic endometrial glands and the presence of \nstroma can cause repeated bleeding of the myometrium. \nRepeated tissue injury and repair caused by adenomyotic \nlesions increases the degree of fibrosis [13]. Ibrahim et al. \nreported the presence of myofibroblasts at the endome -\ntrial myometrial junctional zone in the uteri of patients \nwith adenomyosis, suggesting that the tissue injury and \nrepair mechanism was activated [22–24]. Repeated \ncycles of autotraumatization at the endometrial myome -\ntrial junctional zone can disrupt uterine muscular fibres, \nwhich eventually leads to endometrial basalis invagina -\ntion and inhibits the healing process [13]. Therefore, \ndamage to themyometrium in adenomyosis is not condu-\ncive to healing.\nTable 3 Duration of menstruation and TRM before surgery and at 3, 6 and median months after surgery\nData presented as mean ± SD (range) for duration of menstruation and TRM before surgery and at 3, 6 and median months after surgery\n*  The p-value compared the two time points (before surgery vs at 3 months, before surgery vs at 6 months, before surgery vs at median months) in each group\nNumber \nof \npatients\nAll patients P  value* Adenomyosis group P  value* Non‑adenomyosis group P  value*\nDuration of \nmenstrua-\ntion\nBefore surgery 231 14.3 ± 3.4 (5–30) < 0.001 15.4 ± 4.1 (5–20) < 0.001 14.1 ± 3.2 (5–30) < 0.001\nAt 3 months 8.1 ± 2.4 (3–18) 8.1 ± 1.7 (5–12) 8.1 ± 2.5 (3–18)\nBefore surgery 191 14.4 ± 3.4 (5–30) < 0.001 15.2 ± 4.1 (5–20) < 0.001 14.2 ± 3.2 (5–30) < 0.001\nAt 6 months 8.3 ± 2.3 (4–15) 8.3 ± 2.0 (5–15) 8.3 ± 2.4 (4–15)\nTRM Before surgery 2.7 ± 1.2 (0.5–10.1) < 0.001 2.8 ± 1.1 (1.0–6.0) < 0.001 2.4 ± 1.0 (0.5–10.1) < 0.001\nAt median months 7.4 ± 6.7 (1.0–12.0) 7.6 ± 2.8 (2.0–12.0) 7.3 ± 2.5 (1.0–12.0)\nTable 4 Comparison of follow-up data between two groups after treatment\nData presented as mean ± SD (range) for duration of menstruation and TRM at median months after surgery and TRM at 3 or 6 months after surgery. Data presented as \nnumbers (percentage) for duration of menstruation at median months after surgery, TVS or MRI findings at 3 or 6 months after surgery and Class-A healing\nCSD cesarean scar defect, TVS transvaginal sonography, TRM thickness of the residual myometrium\nVariable Adenomyosis group (n = 50) Non‑adenomyosis group \n(n = 228)\nP value\nDuration of menstruation at median months after surgery 8.1 ± 1.6 (5–12) 8.1 ± 2.3 (3–16.5) 0.883\nDuration of menstruation at median months after surgery\n ≤ 7 days 19(38.0%) 126(55.3%) 0.029\n > 7 days 31(62.0%) 102(44.7%)\nTRM (mm) by TVS at 3 months after surgery 7.9 ± 2.9 (2.0–12.0) 7.5 ± 2.4 (1.9–12.0) 0.460\nTRM (mm) by MRI at 6 months after surgery 5.7 ± 2.9 (3.2–9.6) 4.8 ± 2.3 (1.2–9.9) 0.505\nTRM at median months after surgery by MRI Staging 7.6 ± 2.8 (2.0–12.0) 7.3 ± 2.5 (1.0–12.0) 0.529\nOptimal healing 15 (30.0%) 102 (44.7%) 0.038\nSuboptimal healing 35 (70.0%) 126 (55.3%)\n\nPage 9 of 11\nChen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \n \nA total of 59.3% of the patients in our study achieved \npregnancy after vaginal repair, with eight out of 12 \nwomen with adenomyosis achieving pregnancy, which \nwas slightly higher than that in women without the \ndisorder. Uterine rupture is a catastrophic complica -\ntion during pregnancy and labor, especially for women \nwith a history of cesarean section. The TRM is an indi -\ncator of uterine rupture or dehiscence, and although \nmany risk factors can lead to these outcomes, there is \nan association between a thin TRM and uterine rupture \nor dehiscence [25]. However, the TRM cut-off remains \ncontroversial. It has been reported that the cut-off TRM \nvalue for the risk of uterine rupture should be set at 2.5–\n3.0 mm [4, 26, 27]. In this study, we found that the TRM \nof women who achieved pregnancy and delivered infants \nincreased significantly from 2.3 ± 0.8 mm before sur -\ngery to 7.6 ± 2.9 mm after surgery, and the TRM was not \nless than 3 mm. Therefore, the pregnancy outcome was \nfavorable, and there were no cases of uterine rupture or \ndehiscence. Furthermore, vaginal repair not only reduced \nmenstrual spotting but also reconstructed the uterus to \npreserve fertility in patients with CSDs.\nThere were several limitations in this study. First, our \nstudy was a single- center retrospective study, although \nthe sample size was fairly large. Second, information \non the duration of menstruation and an adenomyosis \nFig. 5 Obstetrical outcomes after vaginal repair of cesarean scar defects\nTable 5 Clinical characteristics of the women who achieved \npregnancy without miscarriage\nData were presented as the means ± SD or percentages\nCSD cesarean scar defect, VR vaginal repair, TRM thickness of the residual \nmyometrium\nDemographic Patients\n(n = 25)\nAge (y) 31.0 ± 3.6 (27–38)\nNumber of cesarean deliveries (n) 1\nMenstruation (d)\n Before VR 13.4 ± 3.3 (7–20)\n After VR 7.6 ± 2.3 (4–14)\nCSD size before VR (mm)\n CSD length 8.8 ± 3.0 (2.9–13.3)\n CSD width 17.4 ± 5.0 (7.0–28.4)\n CSD depth 6.3 ± 2.1 (2.7–10.2)\n TRM 2.3 ± 0.8 (0.5–4.0)\nPersistent CSD after VR, % 32.0 (8/25)\nTRM after VR (mm) 7.6 ± 2.9 (3.0–12.0)\nPreterm birth rate (%) 8.0 (2/25)\nNeonatal birth weight (g) 3224.2 ± 401.0 (2400–4000)\nApgar score (5 min) 10\nPostpartum hemorrhage rate (%) 8.0 (2/25)\nadenomyosis rate (%) 24.0 (6/25)\n\nPage 10 of 11Chen et al. BMC Pregnancy and Childbirth          (2022) 22:187 \ndiagnosis after cesarean section were obtained by mem -\nory, which may have caused bias. Third, the sample \nsize used to generate the data on subsequent pregnan -\ncies after treatment was small; therefore, the relation -\nship between adenomyosis and pregnancy could not \nbe assessed. Therefore, further prospective and large \nmulti-center studies are needed in the future.\nConclusions\nVaginal repair is a minimally invasive surgical proce -\ndure that can reduce postmenstrual spotting and repair \nthe uterus to preserve fertility in patients with CSD. \nBased on the findings of this study, we are cautiously \noptimistic that adenomyosis might be an adverse fac -\ntor for the healing of uterine incisions. Randomized \ndouble-blind controlled studies are needed to verify \nthe positive correlation between myometrial repair and \nadenomyosis treatment.\nAcknowledgments\nThis study was supported by grants from the National Key R&D Program of \nChina (2020YFC2002800) and the National Natural Science Foundation of \nChina (81874103 and 81930064). We thank all the patients, doctors and nurses \nwho participated in this study.\nAuthors’ contributions\nCHH: Data Collection, Manuscript writing. WWJ: Data collection and review. \nWHS: Manuscript writing, Data collection. WXP: Project development, Data \nanalysis. The author(s) read and approved the final manuscript.\nFunding\nThis study was supported by grants from the National Key R&D Program of \nChina (2020YFC2002800) and the National Natural Science Foundation of \nChina (81874103 and 81930064).\nAvailability of data and materials\nThe datasets generated and/or analyzed during the current study are not \npublicly available due personal privacy but are available from the correspond-\ning author on reasonable request.\nDeclarations\nEthics approval and consent to participate\nThis retrospective study was approved by the Ethics Committee of the Shang-\nhai First Maternity & Infant Hospital (KS1512). All patients provided written \ninformed consent. We confirm that all methods were performed in accord-\nance with the relevant guidelines and regulations.\nConsent for publication\nConsent for publication was obtained from all persons.\nCompeting interests\nThe authors declare that they have no conflicts of interest and nothing to \ndisclose.\nAuthor details\n1 Department of Obstetrics and Gynecology, Xin Hua Hospital affiliated \nto Shanghai Jiao Tong University School of Medicine, 1665 Kong Jiang Road, \nYangpu District, Shanghai 200092, China. 2 Department of Radiology, Shanghai \nFirst Maternity and Infant Hospital, Tongji University School of Medicine, \nShanghai 201204, China. \nReceived: 5 September 2021   Accepted: 24 February 2022\nReferences\n 1. Robson SJ, de Costa CM. Thirty years of the World Health Organiza-\ntion’s target caesarean section rate: time to move on. Med J Aust. \n2017;206(4):181–5.\n 2. Li HT, Hellerstein S, Zhou YB, Liu JM, Blustein J. Trends in cesarean delivery \nrates in China, 2008-2018. 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