An interventional study of Double-layer hysterorrhaphy at primary cesarean section and Single-layer hysterorrhaphy at primary cesarean section in Cesarean Scar Defect (Isthmococele), Pelvic Pain and Spotting, sponsored by Hédi Chaker Hospital. Completed at 1 site in Tunisia. Open to female participants aged 18 Years to 45 Years. Per ClinicalTrials.gov, last updated 2026-05-28.
Sponsored by Hédi Chaker Hospital · Not applicable, Interventional, and Other
This study compares two surgical techniques for closing the uterus after cesarean section: single-layer versus double-layer closure. The primary objective is to determine which technique results in better uterine scar healing, measured by residual myometrial thickness (RMT) and cesarean scar defect (niche) prevalence at 6 weeks and 6 months postoperatively.
BACKGROUND:
Cesarean section is one of the most common surgeries worldwide. After fetal delivery, the uterine incision must be closed by suture. Poor scar healing can lead to niche formation, abnormal bleeding, pelvic pain, dyspareunia, and complications in future pregnancies including uterine rupture and placenta accreta.
INTERVENTION:
Participants are randomized 1:1 to receive either:
ASSESSMENTS:
Transvaginal ultrasound at 6 weeks and 6 months measures RMT and niche presence. Standardized symptom questionnaires assess pelvic pain, spotting, dysmenorrhea, and dyspareunia.
ELIGIBILITY:
Women aged 18-45 years undergoing primary cesarean section with singleton pregnancy at term (gestational age ≥ 37 weeks).
ENROLLMENT: 384 participants (192 per group)
SETTING: Department of Obstetrics and Gynecology, Hedi Chaker University Hospital, Sfax, Tunisia
FOLLOW-UP: 6 months per participant in which the patients attend 2 follow-up visits:
First visit 6 weeks after surgery. Second visit at 6 months after surgery
.And have a pelvic ultrasound at each visit
BACKGROUND AND RATIONALE
Cesarean section is one of the most commonly performed surgical procedures worldwide. After fetal delivery, the uterine incision must be closed by suture using one of two accepted techniques: single-layer or double-layer closure. Despite widespread use of both methods : no consensus exists regarding which technique produces superior long-term uterine scar healing.
Poor scar healing can result in a niche. formation (isthmocele), defined as a triangular anechoic indentation of the anterior uterine wall at the scar site with depth greater than or equal to 2 mm (Jordan et al., 2019). Niches occur in 25-70% of women after cesarean section and are associated with postmenstrual spotting, chronic pelvic pain, dyspareunia, fertility impairment, and serious obstetric complications in future pregnancies, including placenta accreta spectrum and uterine rupture.
The residual myometrial thickness (RMT) is the primary ultrasound marker of scar healing quality, defined as the minimum myometrial thickness at the scar site. An RMT below 2.5 mm is associated with a substantially increased risk of uterine rupture in subsequent pregnancies.
Previous studies comparing single-layer and double-layer closure have been limited by heterogeneous populations including scarred uteri, non-standardized surgical techniques, inconsistent ultrasound protocols, and insufficient sample sizes. No study has focused exclusively on primary cesarean sections with a fully standardized operative protocol.
SURGICAL TECHNIQUES
Single-Layer Closure (Group A): The uterine incision is closed with one continuous non-locking suture incorporating the full thickness of the myometrium in one pass, including the decidua.
Double-Layer Closure (Group B): The uterine incision is closed with two successive non-locking extra-mucosal sutures, excluding the decidua. Layer 1 approximates the inner half of the myometrium. Layer 2 buries the first layer, incorporating the outer half of the myometrium and uterine serosa.
All other operative steps are strictly standardized across both groups.
ULTRASOUND ASSESSMENT PROTOCOL
Transvaginal ultrasound (TVUS) is performed by blinded trained sonographers using Samsung HS40 with EVN4-9 probe (4-9 MHz), with empty bladder, preferably in the follicular phase (Day 7-14 of the menstrual cycle), in the mid-sagittal plane.
RMT is measured perpendicular to the serosa at the thinnest scar point. Adjacent myometrial thickness (AMT) is measured 5-10 mm from the scar on both sides. The myometrial ratio is calculated as RM (%) = RMT/AMT x 100.
Niche dimensions (depth, length, width) and volume (ellipsoid formula) are recorded when present.
RANDOMIZATION
Participants are randomized 1:1 using the Clinical Trial Randomization Tool with permuted blocks of variable sizes (4, 6, and 8). Allocation is revealed to the operating surgeon immediately before hysterorrhaphy, after fetal and placentaldelivery. Participants and ultrasound assessors are blinded to group allocation.
STATISTICAL ANALYSIS
Primary analysis uses multiple linear regression for RMT and binary logistic regression for niche prevalence, adjusted for age, BMI, gestational age, uterine exteriorization, surgeon category, and cesarean indication.
Advanced analyses include linear mixed-effects models for repeated measures, Firth penalized logistic regression for predictive modeling, counterfactual mediation analysis (Imai et al.) with bootstrap validation (10,000 replications), inverse probability weighting for loss to follow-up, and five-scenario multiple imputation (MICE).
Software: SPSS v26.0 and R v4.3. Reporting: CONSORT 2010 guidelines.
ETHICAL CONSIDERATIONS
This trial is conducted in accordance with the Declaration of Helsinki (2013), ICH-GCP E6(R2), and Tunisian national regulations. Ethical approval was obtained from the Ethics Committee of the Faculty of Medicine of Sfax (Approval No. 31/26). All participants provide written informed consent. Participation is voluntary and withdrawal is permitted at any time without consequence to medical care.
375 studies on the registry are indexed under Pelvic Pain; 83 are open to participants now.
This study's enrollment of 384 is above the median of 54 across 273 interventional studies indexed under Pelvic Pain.
Browse Pelvic Pain studies →Hédi Chaker Hospital is the lead sponsor of 2 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Participants allocated to this arm undergo primary cesarean section with single-layer uterine closure (hysterorrhaphy). After fetal and placental extraction, the uterine incision is closed in one single layer using a continuous absorbable suture (polyglactin 910 or equivalent), which approximates the myometrium in a running unlocked pattern. No second imbricating layer is performed. Additional interrupted sutures (reinforcement stitches) may be placed if necessary for bleeding control. All participants are followed postoperatively with standardized transvaginal ultrasound assessments at 6 weeks and 6 months to evaluate residual myometrial thickness (RMT) and cesarean scar defect (niche) development, as well as clinical symptom monitoring.
Procedure: Single-layer hysterorrhaphy at primary cesarean section
articipants allocated to this arm undergo primary cesarean section with double-layer uterine closure (hysterorrhaphy). After fetal and placental extraction, the uterine incision is closed in two distinct layers using a continuous absorbable suture (polyglactin 910 or equivalent). The first layer approximates the myometrium with a running unlocked suture. The second layer invaginates the first using a continuous suture to reinforce the closure and improve hemostasis. Additional interrupted sutures (reinforcement stitches) may be placed if necessary for bleeding control. All participants are followed postoperatively with standardized transvaginal ultrasound assessments at 6 weeks and 6 months to evaluate residual myometrial thickness (RMT) and cesarean scar defect (niche) development, as well as clinical symptom monitoring.
Procedure: Double-layer hysterorrhaphy at primary cesarean section
After fetal and placental delivery, the uterine incision is closed in two layers using continuous absorbable suture (polyglactin 910). Layer 1: running suture approximating the full myometrial thickness. Layer 2: continuous imbricating suture reinforcing the first layer and improving hemostasis. Additional reinforcement sutures placed if needed. Aims to optimize uterine scar healing and reduce cesarean scar defect (niche) formation.
Also known as: Two-layer uterine closure, Double-layer uterine closure, HDP technique
After fetal and placental delivery, the uterine incision is closed in one single layer using a continuous absorbable suture (polyglactin 910) approximating the full myometrial thickness in a running pattern. No second reinforcement layer is performed. Additional reinforcement sutures are placed if needed. This represents the conventional standard technique for uterine closure at cesarean section.
Also known as: One-layer uterine closure, Single-layer uterine closure, HPU technique
Residual Myometrial Thickness (RMT) at the Cesarean Scar at 6 Weeks and 6 Months
Residual myometrial thickness (RMT) measured in millimeters at the thinnest point of the uterine scar using standardized transvaginal two-dimensional ultrasound, performed by blinded sonographers according to the protocol of Naji et al. (2012). RMT compared between single-layer (HPU) and double-layer (HDP) closure groups at 6 weeks and 6 months postoperatively.
Time frame: 6 weeks and 6 months after cesarean section
Prevalence of Cesarean Scar Defect (Niche) at 6 Weeks and 6 Months Postoperatively
Cesarean scar defect (niche) defined as a hypoechoic triangular indentation at the site of the uterine incision with depth ≥ 2mm or residual myometrial thickness (RMT)/adjacent myometrial thickness (AMT) ratio \< 50%, detected by standardized transvaginal two-dimensional ultrasound. Prevalence compared between single-layer (HPU) and double-layer (HDP) closure groups at 6 weeks and 6 months postoperatively.
Time frame: 6 weeks and 6 months after cesarean section
Prevalence of Gynecological Symptoms Related to Cesarean Scar Defect
Assessment of symptoms potentially related to uterine scar defect including: postmenstrual spotting, menometrorrhagia, dysmenorrhea, chronic pelvic pain, dyspareunia, urinary symptoms, and abnormal uterine bleeding at day 10 postoperatively. Symptoms assessed by standardized clinical questionnaire at 6 weeks and 6 months. Compared between HPU and HDP groups.
Time frame: Day 10, 6 weeks, and 6 months after cesarean section
Identification of Independent Risk Factors for Cesarean Scar Defect Formation
Identification of independent risk factors for cesarean scar defect (niche) at 6 weeks and 6 months using multivariate logistic regression analysis. Variables assessed include: closure technique, operative duration, use of reinforcement sutures, uterine position, BMI, parity, type of cesarean section (elective vs emergency), and cervical dilation at time of surgery.
Time frame: 6 weeks and 6 months after cesarean section
Cesarean Scar Defect Linear Dimensions
Length, width, and depth of detected cesarean scar defect measured in millimeters by transvaginal ultrasound at 6 weeks and 6 months. Unit of Measure: Millimeters (mm)
Time frame: 6 weeks and 6 months after cesarean section
Cesarean Scar Defect Volume
Estimated volume of cesarean scar defect calculated using ellipsoid formula: V(mm³) = (π/6) × Length × Width × Depth Unit of Measure: Cubic millimeters (mm³)
Time frame: 6 weeks and 6 months post-cesarean
Operative Duration of Hysterorrhaphy and Total Cesarean Section
Measurement of time (minutes and seconds) required for uterine closure (hysterorrhaphy duration) and total operative time from skin incision to skin closure. Number of suture materials used and frequency of additional reinforcement sutures also recorded. Compared between HPU and HDP groups.
Time frame: preoperative (during cesarean section procedure)
Intraoperative Complications Rate
Rate of intraoperative complications including hemorrhage requiring transfusion, bladder injury, ureteral injury, and unintended uterine incision extension. Unit of Measure: Number of events (n) and percentage (%)
Time frame: Perioperative : During cesarean section procedure
Postoperative Infectious Complications Rate
Rate of postoperative infectious complications including endometritis, surgical site infection, and urinary tract infection, assessed during hospitalization and at 6-week visit. Unit of Measure: Number of events (n) and percentage (%)
Time frame: Up to 6 weeks after cesarean section
Hospital Length of Stay
Number of days from cesarean section to hospital discharge. Unit of Measure: Days
Time frame: Up to 5 days after cesarean section
Blood Transfusion Requirement
Number of packed red blood cell units transfused during hospitalization. Unit of Measure: Number of units
Time frame: Up to 5 days after cesarean section
Mediation Analysis: Role of Early Scar Defect in Late Outcome
Formal mediation analysis (Baron-Kenny approach, Sobel test, non-parametric bootstrap with 10,000 replications) to quantify the proportion of the protective effect of double-layer closure on 6-month niche prevalence that is mediated through prevention of early niche formation at 6 weeks. Proportion of mediated effect and direct/indirect effects will be calculated.
Time frame: 6 weeks and 6 months after cesarean section
Development of a Clinical Symptom-Based Predictive Score for Cesarean Scar Defect
Development and internal validation of a clinical predictive score based exclusively on self-reported symptoms (spotting, dysmenorrhea, pelvic pain, cycle irregularity) to identify patients at risk of cesarean scar defect at 6 months, without requiring ultrasound. Firth penalized logistic regression, 10-fold cross-validation, and bootstrap validation will be performed. AUC, sensitivity, specificity, PPV, NPV reported.
Time frame: 6 months after cesarean section
Identification of a Functional RMT Threshold Associated with Symptomatic Risk
Identification of a residual myometrial thickness (RMT) threshold at 6 weeks postoperatively that is associated with increased risk of gynecological symptoms at 6 months, using ROC curve analysis and dose-response gradient assessment. This threshold will complement existing obstetric safety thresholds by adding a functional/symptomatic dimension.
Time frame: 6 weeks and 6 months after cesarean section
Documents are hosted by the registry — open the source record to download them.
Plan to share: No — Individual participant data will not be shared publicly due to patient confidentiality requirements and institutional regulations. Aggregate results will be published in peer-reviewed journals.
This study is completed, as verified in May 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Hédi Chaker Hospital