Evaluation for possible early pregnancy failure



If a yolk sac was present but an embryo wasn’t, the false-positive rate was 2.6% with a mean gestational sac diameter cutoff of 16 mm and 0.4% with a cutoff of 20 mm. Again, there were no false positives when a cutoff of 21 mm was employed.

When a yolk sac and embryo were visible but a fetal heartbeat was not apparent, the false-positive rate for miscarriage was 8.3% with a crown-rump length cutoff of 5 mm. At a cutoff of 5.3 mm, there were no false-positive results (Ultrasound Obstet. Gynecol. 2011;38:497-502).

When Dr. Vrees asked the audience for a show of hands as to who utilizes a mean gestational sac diameter cutoff of 21 mm to define early pregnancy loss in the absence of both a yolk sac and embryo, only a couple of ob.gyns. responded affirmatively. Some audience members indicated they use a cutoff as low as 16 mm.

"We see great variability at our institution, too, in the definition of early pregnancy failure based upon mean gestational sac diameter," according to Dr. Vrees.

The lack of unanimity on this point, coupled with the remote likelihood of physical harm in waiting 7-10 days to repeat an ultrasound scan, figure prominently in her advocacy of expectant management.

She reported having no relevant financial disclosures.

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