Potter et al identified risk factors which may predict failure of single dose methotrexate therapy to treat a woman with a tubal ectopic pregnancy. The presence of one or more of these factors can alert the clinician to consider alternative treatment options. The authors are from Grady Memorial Hospital and Emory University in Atlanta.


Successful therapy was defined as having the serum beta-HCG drop to < 50 mIU/mL.


Failure in therapy was defined as the need to perform a surgical intervention for any reason after giving the initial dose of methotrexate.


85% of women were successfully treated, leaving 15% failing.


Major risk factor for failure (adjusted odds ratio 19):

(1) visualization of a yolk sac within the tube on vaginal ultrasonography


Additional risk factors (adjusted odds ratio 2.2 to 3.8)

(2) pretreatment beta-HCG > 5,000 mIU/mL

(3) decline in serum beta-HCG by < 15% between days 4 and 7, with the serum level on day 7 > 0.85 * (serum level on day 4)

Risk Factor(s)

Risk of Failure

yolk sac visualized


pretreatment HCG AND failure to decline

moderate to high

pretreatment HCG OR failure to decline

low to moderate

no risk factors



Additional risk factors:

(1) failure to receive an additional dose when indicated

(2) development of a contraindication to further methotrexate dose (leukopenia, thrombocytopenia, elevated serum liver function tests, and/or elevated serum creatinine)


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