"Empty" sac in pregnant women with bleeding: are measurements answering the right question?
OBJECTIVE
To assess the percentage of first-trimester pregnancies with bleeding that demonstrate a visible sac but lack an identifiable embryo and have a mean sac diameter (MSD) in the controversial range of 16-20 mm.


METHODS
Retrospective study of all first-trimester sonograms among women with vaginal bleeding during a 4-year interval.


RESULTS
The study cohort consisted of 546 first- trimester sonograms. An embryo was not seen in 132 cases (24%). Of these, the MSD in 69 cases (52%) was <16 mm, between 16 and 19 mm in 20 cases (15%), or >or=20 mm in 39 cases (30%). The percentage of women who were threatening to abort who demonstrated a visible sac but lacked an identifiable embryo and had a MSD in the controversial range of 16-20 mm was 3.7% (20/546).


CONCLUSIONS
We found that of 546 sonograms undertaken in pregnant women with vaginal bleeding in the first trimester, only 20 patients (3.7%) fell in the MSD range of 16-20 mm. Therefore, even among those diagnosticians who adopt the most stringent criterion (MSD = 20 mm), an additional examination would be requested in fewer than 1 in 25 patients.
Aziz
Seerat
S
Department of Radiology, University of California, San Francisco, CA, USA.
Cho
Richard C
RC
Baker
Diana B
DB
Chhor
Chloe
C
Filly
Roy A
RA
D000033:Abortion, Threatened / Q000000981:diagnostic imaging*; D004622:Embryo, Mammalian / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000000981:diagnostic imaging*; D011261:Pregnancy Trimester, First; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods; D014592:Uterine Hemorrhage / Q000000981:diagnostic imaging* / Q000209:etiology