THE ROLE OF ENDOMETRIAL THICKNESS AND SERUM BETA-HUMAN CHORIONIC GONADOTROPIN LEVELS AS PREDICTIVE MARKERS OF DELAYED FAILURE IN MEDICAL ABORTION

Introduction: Medical abortion, also known as medical termination of pregnancy (MToP) or MA, employs pharmaceutical agents to trigger a process similar to miscarriage, serving as an alternative to surgical methods. Extensive evidence, global practices and guidelines from the World Health Organization (WHO) validate the effectiveness of administering 200mg of mifepristone followed by 800mcg of misoprostol taken 24-48 hours later for pregnancies up to nine weeks in gestation. Objective: This study aims to assess the predictive value of ultrasonographic measurements of endometrial thickness and serum human beta chorionic gonadotropin (β - hCG) levels in identifying late failure in patients undergoing medical abortion with mifepristone and misoprostol. Material and Methods: A prospective observational study was carried out at the University Clinic for Gynecology and Obstetrics in Skopje from January to June 2023. The research involved 97 women seeking medical abortions who reported experiencing residual vaginal bleeding lasting 15 days or longer following outpatient medical induction for pregnancies not exceeding nine weeks. Each participant underwent transvaginal ultrasound and serum β-hCG testing prior to cervical dilation and endometrial curettage performed under anesthesia. Based on histopathological analysis of uterine contents, participants were categorized into those with incomplete abortions (19 cases; 19.59%) showing products of conception, and those with complete abortions (78 cases; 80.41%) lacking such evidence. Correlations between transvaginal ultrasound findings and quantitative β-hCG levels with histopathological results were analyzed to determine the reliability of these markers in predicting complete abortion. Results: Baseline characteristics were comparable across both groups. Endometrial thickness measurements showed significant differences: averaging 11.2±3.9mm in the complete abortion group compared to 14.6±6.1mm in the incomplete group (P=0.003). Serum β-hCG levels also varied significantly: averages were found at 73.92±23.86 IU/L for complete abortions versus 109.37±68.36 IU/L for incomplete ones (P<0.001). An endometrial thickness threshold of ≥12mm yielded a sensitivity of 88.46%, specificity of 73.68%, positive predictive value (PPV) of 93.24%, and positive likelihood ratio (LR+ve) of 85.57%. Similarly, a serum β-hCG level ≥100 IU/L indicated incomplete abortion with a sensitivity of 87.2%, specificity of 78.9%, PPV of 94.4% and LR+ve of 85.6. Conclusion: Quantitative serum β-hCG levels along with measurements of endometrial thickness are valuable diagnostic tools for predicting late failure after medical abortion; however, they should be employed as complementary assessments alongside thorough clinical evaluations.