Day 1 change in maternal serum β-HCG levels as an early predictor of successful medical therapy in ectopic pregnancies.

Objective

To evaluate the role of β-HCG level changes between days 0 and 1 as an early predictor of methotrexate success in cases of tubal ectopic pregnancy.

Methods

A retrospective study included 86 tubal ectopic pregnancies treated with a single-dose methotrexate protocol of 50 mg/m2 of body surface. β-HCG measurements were taken on days 0, 1, 4 and 7 where day 0 is the day of methotrexate injection. Day 0 β-HCG and the percentage change in β-HCG level between days 0 and 1 (HCG index) were calculated and compared between patients who were successfully or unsuccessfully treated. Receiver operator characteristics (ROC) curves were plotted to identify the best cutoff levels.

Results

The average level of β-HCG (1416.8 versus 2502.5 IU/L, p=.001) and its increment after 24 hours (12.9 versus 27.1%, p=.001) were significantly lower in the successful treatment group. ROC curves for β-HCG level and its relative increment revealed that cutoff values of ≤1550 IU/L and ≤13% increment showed a sensitivity of 90 and 70% respectively for successful methotrexate treatment.

Conclusion

Day 0 β-HCG level ≤1550 IU/L and an increment of ≤13% after 24 hours are early predictors of successful methotrexate treatment for tubal ectopic pregnancy.