The purpose of the study is to determine whether two-layered simple interrupted myometrial suturing is superior to double-layered continuous suturing for the prevention of uterine niche formation after primary cesarean section.

All primigravidae at or beyond 28 weeks' gestation undergoing primary cesarean section for any indication were assessed for eligibility. All participants provided written informed consent before enrolment. All patients received preoperative antibiotic prophylaxis at induction of anesthesia and postoperative prophylaxis for 24 h. A single intramuscular dose of oxytocin 10 IU was administered during the first 24 h postpartum. After confirming eligibility and obtaining consent, a trained nurse selected an envelope for each patient and revealed the allocation to the operating obstetrician. Patients were blinded to group allocation.

• Study Group: Two-layered simple interrupted suturing of the myometrium, sparing the decidua, with closure of the visceral uterine peritoneum.
• Control Group: Double-layered continuous suturing of the myometrium, sparing the decidua, with closure of the visceral uterine peritoneum.

The parietal peritoneum was left open in all cases. Hemostasis was ensured, and the number of additional hemostatic sutures was recorded. A braided polyglycolic acid 0-1 suture was used in all cases. All other steps of cesarean section were standardized.

At 6 months postpartum, all patients were evaluated by a single blinded sonographer experienced in niche assessment. First, transvaginal ultrasound was performed to exclude pregnancy or pelvic pathology, followed by saline-infusion sonohysterography (2D, sagittal and coronal views). A niche was defined as ≥ 2 mm myometrial indentation at the scar site. Niche depth, length, width, and residual myometrial thickness were recorded.

Menstrual history was obtained by an independent obstetrician/gynecologist, documenting spotting days, total bleeding days, amenorrhea, and contraceptive use.

Inclusion Criteria:

• Acceptance to participate and willingness to attend follow-up for 6 months postpartum.
• No plans for pregnancy within the follow-up period.

Exclusion Criteria:

• Known Müllerian anomalies or uterine fibroids.
• Previous uterine surgery.
• Multiple gestation.
• Chorioamnionitis, placenta previa, or placental abruption.
• Preeclampsia/eclampsia.
• Hepatic or renal dysfunction, uncontrolled diabetes, or systemic disease.
• Peripartum hemoglobin < 10 g/dL.
• Chronic corticosteroid use or smoking.
• Inability to provide consent.