Assessing Uterine Scar Healing After Consecutive Cesareans: Insights from Sonohysterography on Endometrium-Free Closure Technique

Highlight

This study investigates the impact of an endometrium-free uterine closure technique on cesarean scar morphology using saline infusion sonohysterography in women with multiple cesarean deliveries. Key findings include predominance of stable or improved uterine scar morphology after the second endometrium-free closure, a trend toward more favorable outcomes when consecutive endometrium-free closures are performed, and the observation that prior scar condition influences healing patterns. Notably, new niche formation was more frequent when transitioning from a standard to an endometrium-free closure, but findings did not reach statistical significance, meriting further prospective research.

Study Background

Cesarean section (CS) rates have increased worldwide, highlighting concerns about uterine scar integrity and associated risks such as uterine rupture, abnormal placentation, and cesarean scar defects (niches). Scar morphology after CS is an important predictor of potential reproductive complications. Techniques of uterine closure, especially the method of suturing the myometrium and endometrium, may influence scar formation. The endometrium-free closure technique, which excludes the decidual layer from the suture line, has been proposed to improve healing by optimizing myometrial apposition and reducing scar defects. However, evidence on its efficacy, especially after multiple cesareans, remains limited. This study addresses a crucial clinical need by longitudinally tracking scar morphology after successive cesareans with this technique.

Study Design

This small retrospective longitudinal cohort study included 25 asymptomatic women undergoing 2 to 9 consecutive cesarean deliveries, who received multiple saline infusion sonohysterographic exams (2 to 5 per patient) assessing uterine scar morphology. The cohort comprised 40 paired consecutive cesarean procedures that fulfilled inclusion criteria, divided into two groups: the “Transition Group” (n=9), where a first cesarean was performed with a standard closure followed by a cesarean with an endometrium-free closure; and the “Successive Group” (n=31), where two consecutive cesareans utilized the endometrium-free closure technique. Outcome measures included niche presence, niche depth (> 2 mm considered significant), residual myometrial thickness, and morphological changes greater than ±2 mm (operational but not clinically validated). The study employed generalized estimating equations (GEE) to control for intraindividual correlation, with a significance threshold of p<0.05.

Key Findings

Analysis indicated that the Transition Group exhibited a 4.67-fold higher odds of new niche development compared to the Successive Group (OR 4.67; 95% CI: 0.71–30.77), although this difference lacked statistical significance (p=0.109). Mean depth increase of niches was 1.31 mm greater in the Transition Group (p=0.099), but this was likewise not statistically significant. Medians for niche depth changes were 4.6 mm and 3.6 mm for Transition and Successive groups, respectively.

Overall, 55% (22/40) of the paired cases resulted in no niche after the second endometrium-free closure, with stable or improved niche depth or myometrial thickness in a substantial proportion of the remainder. Specifically, 25% (10/40) had stable or improved niche depth; 22.5% (9/40) had stable or improved residual myometrial thickness; 7.5% (3/40) worsened in depth; 5% (2/40) worsened in both depth and residual myometrial thickness; and 15% (6/40) developed new niches with a mean depth of 4.2 mm (range 2.6–6.5 mm) and residual myometrial thickness averaging 5.72 mm.

These outcomes suggest the endometrium-free closure is associated with generally favorable scar morphology preservation, although repeated surgeries may attenuate its benefit. The findings must be interpreted cautiously given the study’s small size, retrospective design, single observer measurements without reproducibility assessment, and absence of correlated clinical outcomes such as uterine rupture risk or obstetric complications.

Expert Commentary

Cesarean scar defects, or niches, are a recognized source of obstetric morbidity, including placenta accreta spectrum disorders and uterine rupture. The endometrium-free closure technique aims to minimize such defects by excluding decidual tissue that may impede robust myometrial healing. This study’s intraindividual, longitudinal approach is a valuable methodological strength, reducing confounding from interpatient variability. The observed trend favoring consecutive endometrium-free closures over a transition from standard to endometrium-free closure aligns with biological plausibility that consistent surgical technique promotes more uniform scar remodeling.

Nevertheless, the lack of significant findings underscores the need for larger, prospective cohort studies or randomized trials with clinically relevant endpoints. Particularly, correlating niche morphology with symptoms, fertility outcomes, and subsequent pregnancy complications would clarify the clinical impact. Additionally, future work should include standardized ultrasound measurement protocols with interobserver reliability assessments to enhance data robustness.

In clinical practice, these findings, though preliminary, support consideration of endometrium-free closure as a potentially beneficial technique for uterine repair in women likely to have multiple cesareans. Surgical training emphasizing this method and sonographic surveillance could be integrated into obstetric care pathways.

Conclusion

This small retrospective study indicates that endometrium-free closure of the uterine incision during cesarean delivery generally preserves favorable uterine scar morphology after consecutive cesarean deliveries. Scar integrity is influenced both by prior scar condition and closure technique. The transition from standard to endometrium-free closure may carry a higher risk of niche development, although not statistically confirmed. Importantly, repeated cesareans may limit the morphological benefit of closure methods in some women. These results highlight a promising surgical approach but underscore the critical need for prospective trials evaluating its efficacy on clinically meaningful outcomes, including safety and reproductive performance.

Until stronger evidence emerges, clinicians should weigh current findings alongside individual patient risk factors and surgical expertise when selecting uterine closure techniques.

Funding and Registration

The article did not specify study funding sources or clinical trial registration identifiers.

References

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