Comparison of transvaginal and transabdominal sonography in the detection of early pregnancy and its complications

Ninety women with a positive pregnancy test and signs and symptoms of threatened abortion or ectopic pregnancy had endovaginal and abdominal sonography in order to compare the value of the two techniques for the detection of gestational abnormalities. Either a normal delivery occurred or surgical and/or pathologic confirmation of the diagnosis was available in all cases. Fifty-five women had normal intrauterine pregnancies, 22 had ectopic pregnancies, seven had blighted ova, and six had missed abortions. All 55 normal intrauterine pregnancies were detected by endovaginal sonography, while only 11 (20%) were diagnosed by transabdominal sonography. The yolk sac, fetal pole, and fetal heart motion were seen as early as 34 days from the last menstrual period with endovaginal sonography, compared with 42 days with transabdominal sonography. Fetal heart motion was detected with endovaginal sonography in fetal poles with a crown-rump length of 3 mm or greater, whereas the fetal pole had to be at least 6 mm before fetal heart motion could be detected with the transabdominal technique. In the 22 ectopic pregnancies, a specific diagnosis of an extrauterine sac containing a fetal pole with heart motion or yolk sac was possible in three cases with the endovaginal technique, but it was not possible in any case with transabdominal sonography. Both techniques showed that each of the seven patients with final diagnosis of blighted ova had a gestational sac that was 1.7 cm or larger without visualization of the fetal pole or yolk sac. All six missed abortions were detected by endovaginal sonography, but only three were diagnosed on transabdominal sonograms. Our findings show that endovaginal sonography is more sensitive than transabdominal sonography in the detection of early pregnancy and its complications.