Cesarean Scar Niche: Risk Factors, Clinical Consequences, and Diagnostic Modalities - A Narrative Review

Abstract

Cesarean scar niche is a defect of the myometrium at the site of a previous Cesarean section scar. Its reported prevalence varies widely according to the definition used, the studied population, the timing of evaluation, and the imaging modality. The condition results from impaired healing of the uterine incision and is influenced by surgical technique, intraoperative events, uterine anatomy, obstetric circumstances, and patient-related factors. Potential surgical determinants include the uterine incision site, single- or double-layer closure, locked or unlocked sutures, endometrial inclusion, suture material, uterine exteriorization, hemostatic technique, and visceral peritoneal closure. Cesarean scar niche may remain asymptomatic or may be associated with postmenstrual spotting, prolonged menstruation, dysmenorrhea, pelvic pain, dyspareunia, secondary infertility, Cesarean scar pregnancy, placenta accreta spectrum, and uterine rupture in subsequent pregnancy. Transvaginal ultrasound is the first-line diagnostic modality, saline infusion sonohysterography improves visualization and detection, and magnetic resonance imaging is reserved for complex or inconclusive cases. This narrative review summarizes the definition, epidemiology, pathophysiology, risk factors, clinical consequences, and diagnostic modalities of Cesarean scar niche, with particular attention to potentially modifiable surgical factors.