High-Frequency Transabdominal Ultrasound Can Obviate the Need for Transvaginal Ultrasound in Early Pregnancy

Daniel J. Pallin, MD, MPH reviewing Tabbut M et al. Am J Emerg Med 2015 Nov 3.
A third of transvaginal ultrasound exams were avoided by use of the high-frequency probe.

In patients with first trimester pain or bleeding, documentation of an intrauterine pregnancy is used as evidence of the absence of an ectopic pregnancy, given the rarity of heterotopic pregnancies (which occur in about 1/30,000 normal pregnancies and 1/4,000 assisted reproductive technology pregnancies). The standard approach is to obtain a transabdominal scan using the low-frequency curvilinear probe, and if no intrauterine pregnancy is visualized, to perform a transvaginal scan. Investigators from a single emergency department evaluated whether a high-frequency linear probe could be used to detect more intrauterine pregnancies transabdominally, thereby obviating the need for some transvaginal scans.

Of 81 women with first trimester pain or bleeding, 27 had negative transabdominal scans with the low-frequency curvilinear probe. Of these, 9 (33%) had visible intrauterine pregnancies with the high-frequency linear probe. Of the remaining 18 women who had negative scans with both probes, transvaginal scans identified intrauterine pregnancies in 3.

Citation(s):

Tabbut M et al. High-frequency linear transducer improves detection of an intrauterine pregnancy in first trimester ultrasound. Am J Emerg Med 2015 Nov 3; [e-pub].