Increment in beta-hCG in the 48-h period prior to treatment: a new variable predictive of therapeutic success in the treatment of ectopic pregnancy with methotrexate.

BACKGROUND

To evaluate the increment in beta-hCG levels (%) in the 48-h interval prior to treatment as a predictor of therapeutic success in the management of ectopic pregnancy with methotrexate.

METHODS

A prospective observational study was carried out between April 2002 and November 2006 at the Federal University of São Paulo in 65 patients with an ectopic pregnancy treated with a single dose of 50 mg/m(2) of methotrexate administered intramuscularly. The following predictive factors were evaluated: beta-hCG level on the day of hospital admission and the percent increment in beta-hCG in the 48-h interval prior to treatment.

RESULTS

Treatment was successful in 49 cases (75.4%). In these cases, beta-hCG levels at hospitalization were lower when compared to the levels found in cases of therapeutic failure (1,928.9 vs. 4,828.6 mIU/ml, respectively; P<0.01), and the increment in beta-hCG level in the 48-h interval prior to treatment was smaller (13.1 vs. 36.3%, respectively; P=0.01). A beta-hCG measurement <or=2,685 mIU/ml on the day of hospitalization and an increment in beta-hCG level <or=11.1% in the 48 h preceding treatment were factors indicative of therapeutic success with sensitivity of 79.6 and 61.7%, respectively, and specificity of 75 and 81.3%, respectively.

CONCLUSIONS

The lower the beta-hCG measurement on the day of hospital admission and the lower its increment in the 48-h interval prior to treatment, the greater the likelihood that treatment of ectopic pregnancy with methotrexate will be successful. The margin of safety for treatment with methotrexate is high when beta-hCG measurement on the day of hospitalization is <or=2,685 mIU/ml and its increment in the 48 h prior to treatment is <or=11.1%.