Incidence and Time to Niche Development Following Cesarean Delivery: Retrospective Analysis of a National...

The development of uterine niche-also known as cesarean scar defect or isthmocele-is a potential long-term sequela after cesarean delivery, and may be associated with abnormal uterine bleeding, pelvic pain, and infertility. Previous literature examining prevalence consists of small cohort and case control studies. We aimed to calculate the incidence of uterine niche after primary cesarean delivery using a nationally representative database.

Retrospective cohort study.

Vizient Clinical Database.

Individuals who underwent primary singleton cesarean delivery within the Vizient Clinical Database 2021-2024. Vizient is a healthcare performance improvement company that receives de-identified administrative and patient claims data.

Primary cesarean delivery.

Niche cases were identified using International Classification of Diseases (ICD)-10 codes and imaging findings. The primary outcome was incidence of uterine niche, defined as number of cases of niche divided by the person-time-at-risk after primary cesarean delivery. Secondary outcomes included time to niche development and risk factors associated with niche. Overall, 517,763 individuals underwent primary cesarean delivery during the study period. The mean age of the cohort was 32.7 years (SD 6.2) at primary cesarean delivery. There were 62,433 (12.1%) niche events over 915,842 person-years, resulting in an incidence rate of 68.2 events per 1,000 person-years after primary cesarean delivery (95% CI 67.6-68.7). Overall, 98.3% of niche cases developed after the first cesarean delivery, 1.6% after the second, and 0.2% after the third or more. Mean time to diagnosis following primary cesarean delivery was 0.79 years (SD 0.58). On multivariable logistic regression, increased age, Back, Asian, or Hispanic race or ethnicity, history two or more deliveries, having non-commercial insurance, and history of tobacco use were associated with increased likelihood of developing a uterine niche.

The population incidence of uterine niche following cesarean delivery was 68.2 per 1,000 person-years, with mean time to diagnosis 0.79 years after primary cesarean. These data should inform complete counseling regarding the risks of cesarean delivery.