The effect of uterine closure technique on cesarean scar niche development after multiple cesarean deliveries

Objectives: To use saline infusion sonohysterography (SIS) to evaluate the effect of uterine closure technique on niche formation after multiple cesarean deliveries (CDs).Methods: Patients with at least one prior CD were evaluated for niche via SIS. Subgroups of any number repeat CD (>1 prior), lower-order CD (<4 prior), and higher-order CD (>= 4 prior) were analyzed, stratifying by hysterotomy closure technique at last cesarean preceding imaging; techniques included Technique A (endometrium-free double-layer closure) and Technique B (single- or double-layer routine endo-myometrial closure). Niche defects were quantified (depth, length, width, and residual myometrial thickness). The primary outcome was clinically significant niche, defined as depth >2 mm. Statistical analysis was performed using chi-square, ANOVA, t-test, Kruskal-Wallis, and multiple logistic regression, with p-values of <0.05 were statistically significant.Results: A total of 172 post-cesarean SIS studies were reviewed: 105 after repeat CDs, 131 after lower-order CDs, and 41 after higher-order CDs. Technique A was associated with a shorter interval to imaging and more double-layer closures. Technique B was associated with more clinically significant niches across all subgroups, and these niches were significantly longer and deeper when present. Multiple logistic regression demonstrated a 5.6, 8.1, and 11-fold increased adjusted odds of clinically significant niche following Technique B closure in the repeat CD (p<0.01), lower-order CD (p<0.001), and higher-order CD (p=0.04) groups, respectively.Conclusions: While multiple CDs are known to increase risk for niche defects and their sequelae, hysterotomy closure technique may help to reduce niche development and severity.