Uterine Isthmocele (Cesarean Scar Defect / Uterine Niche)

By RRM Academy Reviewed by Dr. Naomi Whittaker, MD, Board-Certified OBGYN, MIGS, NFPMC, FCI Updated May 7, 2026

A myometrial defect (a pouch or indentation) in the anterior wall of the lower uterine segment (isthmus) at the site of a previous cesarean section scar, representing discontinuity of the myometrium. Caused by incomplete or defective healing of the uterine closure at the time of cesarean delivery. The defect creates a reservoir in which menstrual blood pools, then drains slowly, resulting in characteristic post-menstrual brown spotting. The retained blood creates a hostile microenvironment for sperm and may impair implantation, contributing to secondary infertility and increased miscarriage risk when the wall is thin. Prevalence is approximately 20% or more in women with prior cesarean deliveries.¹⁵¹⁶³⁴

Diagnosis: Transvaginal ultrasound (TVUS) and saline infusion sonohysterography (SIS) are the preferred diagnostic tools, both sensitive and cost-effective. SIS allows measurement of the defect dimensions and critically, the residual myometrial thickness (RMT). Treatment decisions depend on symptom profile, RMT, and future fertility desires.⁴³¹⁶¹⁵

Treatment classification:

Approach	Method	Best For	Key Consideration
Hysteroscopic	Internal shaving/cautery of defect	Bleeding symptoms; RMT >5mm; no future pregnancy desired	Faster recovery; may not fully resolve bleeding; does not rebuild wall³⁴
Laparoscopic	Excision + multi-layer reconstruction	Fertility desire; RMT <5mm; preferred overall	Rebuilds wall integrity; better symptom resolution; longer recovery¹⁵
Combined	Laparoscopic + hysteroscopic	Complex defects	Allows concurrent visualization of cavity and external repair

Sources

Isthmocele: an overview of diagnosis and treatment. . SciELO
Isthmocele: an overview of diagnosis and treatment. . PubMed
Isthmocele: From Risk Factors to Management. . PMC
Presentation of isthmocoele and its management options: a review. . Gynaecology & Obstetrics Journal

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.