Journal of Ultrasound in Medicine, Vol 10, Issue 2 63-67, Copyright © 1991 by American Institute of Ultrasound in Medicine
Prospective comparison of vaginal and abdominal sonography in normal early pregnancy
R. G. Pennell, L. Needleman, T. Pajak, O. Baltarowich, M. Vilaro, B. B. Goldberg and A. B. Kurtz
Department of Radiology, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania.
Vaginal and abdominal sonography were prospectively compared in 309
consecutive pregnancies of which 175 were normal. Two sonographic criteria
of normal were analyzed: (1) the presence of an embryo compared with
average gestational sac size and (2) the presence of embryonic cardiac
activity compared with crown-rump length. Vaginally, 100% (160/160) of
embryos were visualized when the average sac diameter was greater than or
equal to 12 mm. Abdominally, an embryo was noted in 99.2% (123/124) of
gestational sacs greater than or equal to 27 mm. Vaginal sonography
revealed cardiac motion in all embryos of greater than or equal to 5 mm
(149/149 cases); abdominal sonography revealed cardiac activity in 100%
(132/132) of embryos with a crown-rump length of greater than or equal to 9
mm. One-third of normal embryos less than 5 mm crown-rump length did not
demonstrate cardiac activity. The study demonstrates through objective
comparison that vaginal sonography is superior to abdominal sonography for
detection of an intrauterine embryo and its cardiac activity before 8
menstrual weeks. The diagnosis of embryonic demise should not be made by
vaginal sonography in embryos measuring less than 5 mm crown-rump length
without a heartbeat, and an empty gestational sac of less than 12 mm
average diameter should not be diagnosed as blighted ovum by vaginal scans.
In these cases follow-up vaginal sonography is suggested.
