Post protocol residual thickness as a negative predictor for pharmacological treatment in early pregnancy loss

To determine the rate of pharmacological treatment failure in early pregnancy loss, assess post-treatment residua thickness as a predictor of retained products of conception (RPOC), identify a clinically relevant cutoff, and evaluate additional clinical and sonographic predictors.

This retrospective cohort study was conducted at a tertiary medical center and included patients treated with mifepristone-misoprostol for first-trimester pregnancy loss between January 2019 and January 2022. Treatment success was assessed via transvaginal ultrasound, with residua thickness measured 14 days post-treatment. The primary outcome was failure, defined as histologically confirmed RPOC following hysteroscopy. Secondary analyses evaluated clinical and sonographic predictors, focusing on post-treatment residual thickness. Statistical analysis included receiver operating characteristic (ROC) curve assessment and multivariable logistic regression.

Of the 717 patients included, 537 (74.9%) achieved successful medical management without further intervention, while 180 (25.1%) required intervention. Treatment failure was associated with greater post-treatment residua thickness (mean 19.1 ± 9.1 mm vs. 10.4 ± 6.7 mm, P < 0.001). Residua thickness was an independent predictor of failure (adjusted odds ratio [aOR] 1.17, 95% confidence interval [CI]: 1.13-1.21, P < 0.001). ROC analysis identified an optimal cutoff of 14.9 mm, yielding 70% sensitivity and 81% specificity (area under the curve [AUC]: 0.835, 95% CI: 0.80-0.87) for predicting the need for surgical intervention.

Post-treatment residual thickness is a significant predictor of pharmacological treatment failure in early pregnancy loss, with a clinically relevant cutoff of approximately 15 mm. Histologic validation provides a promising framework for refining management protocols, emphasizing the need for further studies to establish robust predictive criteria.