Presence of a yolk sac on transvaginal sonography is the most reliable predictor of single-dose methotrexate treatment failure in ectopic pregnancy.
OBJECTIVE
The purpose of this study was to determine which imaging characteristics can be used as prognostic indicators in conjunction with beta-human chorionic gonadotropin (beta-hCG) levels in the treatment of ectopic pregnancy (EP) with single-dose methotrexate (MTX).


METHODS
A retrospective study was performed on 62 patients (age range, 16-47 years; mean, 29 years) treated with MTX for EP from November 2000 to August 2003. The transvaginal sonographic findings in each case were analyzed for the presence and size of an extraovarian mass or a pseudogestational sac, amount of free fluid, presence of a yolk sac, and fetal heart motion. Patient age and beta-hCG level were also noted. Success of treatment was defined as a single dose of MTX that resulted in appropriate lowering of beta-hCG levels.


RESULTS
Of 62 patients, 17 (27%) had single-dose MTX treatment failure. A yolk sac was identified in 15 (88%) of the 17 treatment failures and in none of the cases in which treatment was successful (positive predictive value, 100%). The average beta-hCG level in the cohort of patients who had single-dose treatment failure was 3282 mIU/mL compared with 1544 mIU/mL in the treatment success cohort. The presence of fetal heart motion was seen in only 1 patient, and this patient had treatment failure. The age of the patient, size of the extraovarian mass, presence of a pseudogestational sac, and amount of free fluid did not correlate with outcome.


CONCLUSIONS
The presence of a yolk sac was always associated with treatment failure in single-dose MTX treatment of EP and was the most reliable predictor of failure among all features analyzed. The beta-hCG level was a useful adjunct. A prediction rule was created correlating the probability of treatment success with the beta-hCG level.
Bixby
Sarah
S
Department of Radiology, Boston University Medical Center, 1 Boston Medical Center Pl, Boston, MA 02115, USA. sdbixby@alumni.princeton.edu
Tello
Richard
R
Kuligowska
Ewa
E
D000020:Abortifacient Agents, Nonsteroidal / Q000008:administration & dosage*; D000293:Adolescent; D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004305:Dose-Response Relationship, Drug; D019160:Endosonography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007273:Injections, Intramuscular; D008727:Methotrexate / Q000008:administration & dosage*; D008875:Middle Aged; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000097:blood / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D012189:Retrospective Studies; D017211:Treatment Failure; D014621:Vagina; D015017:Yolk Sac / Q000000981:diagnostic imaging*
D000020:Abortifacient Agents, Nonsteroidal; D018997:Chorionic Gonadotropin, beta Subunit, Human; D008727:Methotrexate