Endometrial thickness and serum beta-hCG as predictors of the effectiveness of oral misoprostol in early pregnancy failure.

OBJECTIVE

To evaluate ultrasonographic measurement of endometrial thickness and serum levels of chorionic gonadotropin (beta-hCG) as predictors of failure to abort completely in patients designated for uterine evacuation using oral misoprostol.

METHODS

Women 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 beta-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 beta-hCG were correlated with the histopathological results to determine the accuracy of these markers in predicting complete abortion.

RESULTS

Baseline characteristics for both groups were similar. The endometrial thickness in the two groups ranged from 11.2 +/- 3.9 mm in the complete abortion group to 14.6 +/- 6.1 mm in the incomplete abortion group, a statistically significant difference (P = 0.003). Serum beta-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 > or = 12 mm 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 beta-hCG > or = 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.

CONCLUSION

Quantitative assay of serum beta-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.