Cesarean scar defects and abnormal uterine bleeding: a systematic review and meta-analysis

Objective: To synthesize the published literature to better understand the association between cesarean scar defects (CSDs) and abnormal uterine bleeding (AUB). In particular, we aimed to evaluate the risk and pattern(s) of CSD-associated AUB in addition to exploring the relationship between defect morphology with bleeding symptoms.

Design: Systematic review and meta-analysis.

Setting: Not applicable.

Patients: Patients with CSD and reports of uterine bleeding as an outcome were identified in 60 studies from database searches.

Interventions: Studies that investigated CSD (as defined by investigators) and reported uterine bleeding, menstrual bleeding, or AUB as an outcome were included.

Main outcome measures: The prevalence and risk of AUB (intermenstrual, postmenstrual, and unscheduled bleeding) in patients with confirmed CSD.

Results: Nine studies reported on the prevalence of AUB in patients with a confirmed CSD. Patients with CSD were more likely to experience AUB, compared with those without CSD (relative risk, 3.47; 95% confidence interval [CI], 2.02-5.97; 6 studies, 1,385 patients; I² = 67%). In a population of patients with at least 1 cesarean delivery, the prevalence of AUB in those with CSD was 25.5% (95% CI, 14.7-40.5; 6 studies, 667 patients, I² = 93%). However, symptom prevalence was much higher in patients presenting for imaging for a gynecologic indication where the prevalence of AUB in the presence of a CSD was 76.4% (95% CI, 67.8-83.3; 5 studies, 505 patients; I² = 71%). The mean menstrual duration in symptomatic patients with CSD was 13.4 days (95% CI, 12.6-14.2; 19 studies, 2,095 patients; I² = 96%), and the mean duration of early-cycle intermenstrual bleeding was 6.8 days (95% CI, 5.7-7.8 days; 9 studies, 759 patients; I² = 93%). The most common descriptor of CSD-associated AUB was "brown discharge". Patients with larger CSD experienced more bleeding symptoms.

Conclusion: There is a strong and consistent association between patients with CSD and AUB. These patients experience a unique bleeding pattern, namely prolonged menstruation and early-cycle intermenstrual bleeding. These data should provide impetus for including CSD as a distinct entity in AUB classification systems. High heterogeneity in our results calls for standardization of nomenclature and outcome reporting for this condition.