Ultrasound predicts outcome of ectopic pregnancy remedy

April 2, 2006

Results from a new study confirm that ultrasound reliably predicts success and failure of single-dose methotrexate treatment of ectopic pregnancy. On the basis of their findings, Boston Medical Center researchers say a change is needed in clinical protocols.

Results from a new study confirm that ultrasound reliably predicts success and failure of single-dose methotrexate treatment of ectopic pregnancy. On the basis of their findings, Boston Medical Center researchers say a change is needed in clinical protocols.

Results from a retrospective trial of 62 patients indicate that yolk sac and fetal heart motion observed with transvaginal ultrasound predicted all 17 treatment failures. A yolk sac was identified in 15 of 17 failed cases, producing a specificity and sensitivity of 88% and 100%, respectively. Fetal heart motion was observed in one patient who failed treatment and was not present in any successful cases. The study was presented by Dr. Sarah Bixby, a BMC radiologist, at the 2005 RSNA meeting.

Methotrexate has been a front-line treatment for ectopic pregnancy since 1992, but the success rate of the single-dose therapy varies widely, ranging from 64% to 94%. Although methotrexate does not have significant risks, it can lead to life-threatening complications, including hospitalization and surgery in up to 29% of women receiving the therapy.

Overall, Bixby found that a patient's beta-HCG hormone rate offered the strongest predictor of methotrexate treatment failure. Although the success rate for all 62 patients was 76%, it fell to 50% in patients with beta-HCG values more than 2000, and to 20% in patients with values over 5000.

Nonetheless, the findings of yolk sac and heart motion with transvaginal ultrasound were the surest indicators that single-dose methotrexate will not work. They should be listed as exclusion criteria in the procedure's clinical protocol, Bixby said.

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