Predictors of Success of Methotrexate Treatment in Women With Tubal Ectopic Pregnancies

Abstract

Presently, methotrexate is a common treatment for tubal ectopic pregnancy. In this trial, the investigators examined the role of several pretreatment factors on the outcome of intramuscular methotrexate therapy in 350 women with tubal ectopic pregnancies. They included the baseline serum chorionic gonadotropin (CG) and progesterone levels, the size and volume of the conceptus, blood in the peritoneal cavity, and fetal cardiac activity. The criterion for success was resolution of the pregnancy without the need for surgery. Methotrexate was given in single doses of 50 mg/m2. With one exception, surgery was performed if the serum CG did not respond after three doses or if fetal cardiac activity remained evident. At baseline, about three-fourths of women had an ectopic tubal mass on transvaginal ultrasonography, and one-third had free peritoneal fluid, presumably blood, limited to the pelvis. Methotrexate therapy succeeded in 91 percent of cases. Age, parity, and the size or volume of the ectopic mass did not predict the outcome, nor was the presence of peritoneal fluid a factor. Successfully treated women did, however, have lower serum CG and progesterone levels and less frequent fetal cardiac activity. Average serum CG levels were 4019 and 13,420 mIU/ml in the successful and failed cases, respectively, and the progesterone levels averaged 6.9 and 10.2 ng/ml. Fetal cardiac activity was present in 12 percent of successfully treated cases and 30 percent of failed cases. On regression analysis, a high baseline serum CG level was the only factor significantly predictive of treatment failure. Just more than 80 percent of women in the study and 82 percent of those who responded received a single dose of methotrexate. Serum progesterone (but not CG) was higher in women given more than one dose, as was the frequency of fetal cardiac activity. In this series, the baseline serum CG concentration was the most powerful predictor of success in women given intramuscular methotrexate on a single-dose protocol for ectopic pregnancy. Relatively high levels mean a greater risk of treatment failure. N Engl J Med 1999;341:1974–1978