Tracking cesarean scar morphology by sonohysterography after consecutive cesarean deliveries with endometrium-free...

Scar morphology over time during consecutive cesarean deliveries has not been tracked in the same women. The endometrium-free closure technique has been associated with improved sonohysterographic scar morphology, but whether it improves the scar within the same patient compared with a prior closure performed with either the standard or endometrium-free technique remains unknown. This study used paired sonohysterography to assess niche development in the same patients after consecutive cesarean deliveries, with endometrium-free closure consistently applied in the second delivery.

To evaluate the impact of an endometrium-free closure on uterine scar morphology by comparing sonohysterograms in the same women, first after a cesarean with a standard or an endometrium-free closure and then after a subsequent cesarean with an endometrium-free closure.

This small retrospective longitudinal study used saline infusion sonohysterography to assess uterine scar morphology in 25 asymptomatic women who underwent 2 to 5 sonographic examinations following 2 to 9 consecutive cesarean deliveries. Forty paired consecutive procedures in which the second delivery used an endometrium-free closure technique met the inclusion criteria, categorized as "Transition Group" (n=9), in which a standard closure was followed by an endometrium-free closure, and "Successive Group" (n=31), in which women received the endometrium-free closure technique in 2 successive deliveries. Paired sonohysterographic analyses were performed after each cesarean delivery and longitudinally compared to evaluate niche development and scar morphology. Niche depth and residual myometrial thickness were measured; a niche depth greater than 2 mm was considered sonographically significant. A change greater than ±2 mm in depth or residual myometrial thickness was operationally defined as morphologically significant and not clinically validated. Generalized estimating equations with robust standard errors were used to account for within-patient correlation (P value <.05).

By generalized estimating equations analysis, the Transition Group had 4.67-fold higher odds of new niche development compared to the Successive Group (odds ratio=4.67; 95% confidence interval, 0.71-30.77; P=.109). This difference did not reach statistical significance. Mean depth change was 1.31 mm greater in the Transition Group (B=1.31; 95% confidence interval, 0.25-2.87; P=.099). Transition Group pairs showed larger depth increases (median 4.6 mm, range, 3.0-5.0 mm) compared with Successive Group pairs (median 3.6 mm; range, 2.6-5.3 mm). These findings should be interpreted as hypothesis-generating only, not as evidence of clinical significance. Across both groups, 22/40 pairs (55.0%) ended without a niche after the second endometrium-free closure, including 21 (21/22, 95.5%) that initially presented without a niche and 1 (1/22, 4.5%) that initially presented with a niche. Ten pairs (10/40, 25.0%) that presented with preexisting niches showed stable or improved niche depth, and 9 pairs (9/40, 22.5%) of these cases showed stable or improved residual myometrial thickness, 3/40 (7.5%) worsened in depth, 2/40 (5.0%) simultaneously worsened in residual myometrial thickness, 6/40 (15.0%) developed a de novo niche, mean depth 4.2 mm (2.6 mm-6.5 mm), and mean residual myometrial thickness of 5.72 mm (3.50 mm‑7.30 mm).

In this small retrospective intraindividual cohort, the endometrium-free closure maintains favorable sonographic scar morphology in most women, with morphology reflecting both prior scar status and the technique at delivery. Repeated surgery may limit the benefit of closure technique in some women, although many maintained scar morphology even at higher-order cesareans. Results are limited by single-observer measurements without reproducibility assessment, use of ±2 mm threshold, and absence of clinical outcomes. These paired observations warrant prospective evaluation in larger studies.