Endometrial Thickness and Serum β-hCG as Predictors of the Effectiveness of Oral Misoprostol in Early Pregnancy Failure

Abstract

ObjectiveTo evaluate ultrasonographic measurement of endometrial thickness and serum levels of chorionic gonadotropin (β-hCG) as predictors of failure to abort completely in patients designated for uterine evacuation using oral misoprostol. MethodsWomen attending an obstetric outpatient clinic who complained of residual vaginal bleeding 15 days or more after taking oral misoprostol for medical induction of abortion for early pregnancy failure were evaluated by transvaginal ultrasound scan and assay of serum β-hCG. They subsequently underwent dilatation and curettage under general anaesthesia. According to the results of histopathological examination of uterine contents, the study cohort was divided into women with incomplete abortion (19 cases, 19.6%) and cases with complete abortion (78 cases, 80.4%). The results of the ultrasound scan and the assay of serum β-hCG were correlated with the histopathological results to determine the accuracy of these markers in predicting complete abortion. ResultsBaseline characteristics for both groups were similar. The endometrial thickness in the two groups ranged from 11.2 ± 3.9mm in the complete abortion group to 14.6 ± 6.1mm in the incomplete abortion group, a statistically significant difference (P = 0.003). Serum β-hCG levels were statistically different in the two groups (complete abortion 73.9 ± 23.9 IU/L vs. incomplete abortion 109.4 ± 68.4 IU/L, P < 0.001). Measured endometrial thickness ≥ 12mm predicted incomplete abortion with a sensitivity of 88.5%, a specificity of 73.7%, a positive predictive value (PPV) of 93.2%, and a positive likelihood ratio (LR+ve) of 85.6. A serum β-hCG ≥-100 IU/L predicted incomplete abortion with a sensitivity of 87.2%, a specificity of 78.9%, a PPV of 94.4%, and a LR+ve of 85.6. ConclusionQuantitative assay of serum β-hCG and ultrasound measurement of endometrial thickness are clinically useful measures for predicting late failure of medical abortion, but should be used as supplements to clinical assessments.