When an obstetrical patient was referred for inability to auscultate f
etal heart tones at 18 weeks' gestation, ultrasound identified a singl
e living fetus in the maternal right upper quadrant, Magnetic resonanc
e imaging (MRI) ruled out a suspected uterine ectopic pregnancy and av
oided laparotomy. The patient experienced an uncomplicated term delive
ry, MRI is a useful adjunct to ultrasound for mid-trimester pregnancy
localization when the differential diagnosis includes uterine eccyesis
.