Uterine Isthmocele (Cesarean Scar Defect / Uterine Niche)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 14, 2026

An isthmocele (also called a cesarean scar defect or uterine niche) is a myometrial deficiency at the anterior wall of the lower uterine segment, occurring at the site of a prior cesarean scar where the uterine wall failed to heal with full thickness. The defect creates a pouch where menstrual blood pools and drains slowly, producing the characteristic symptom of prolonged post-menstrual brown spotting. Blood retained in the niche creates a microenvironment hostile to sperm transit and may impair embryo implantation, contributing to secondary infertility and elevated early pregnancy loss risk in women with an inadequate residual myometrial wall.¹²³

Transvaginal ultrasound (TVUS) and saline infusion sonohysterography (SIS) are the preferred initial imaging tools. SIS allows direct measurement of defect dimensions and residual myometrial thickness (RMT), which is the critical variable driving repair decisions. Hysteroscopy provides direct intracavitary visualization and can be both diagnostic and operative in a single procedure.⁴⁵⁶

Repair approach depends on defect severity, RMT, and the patient's fertility goals. Hysteroscopic repair addresses the defect from within the uterine cavity and is well suited for symptom control when the myometrial wall is adequate. Laparoscopic repair involves excision of the defect with multi-layer reconstruction of the uterine wall, and is the preferred approach when wall integrity is compromised or when future pregnancy is desired. Complex defects may require a combined approach using both techniques simultaneously.¹³

This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.