New consensus-based guidance allows better determination of location and viability of pregnancy.
Andrew M. Kaunitz, MD; , October 9, 2013.
Transvaginal ultrasound (TVUS) and serial measurement of serum human chorionic gonadotropin (hCG) have transformed the assessment of pregnant women with early pain and/or bleeding or with other risk factors for ectopic pregnancy (EP) or nonviable intrauterine pregnancy (IUP). With widespread use of these diagnostic modalities, clinicians in obstetrics and gynecology, radiology, emergency medicine, and primary care increasingly encounter early pregnancies of uncertain viability and unknown location — but interpreting the test results to determine appropriate interventions remains challenging. Accordingly, experts in radiology and obstetrics and gynecology have developed a consensus statement from the Society of Radiologists in Ultrasound based on current published data.
The panel states that definitive pregnancy failure can be diagnosed in a woman with an IUP of uncertain viability when TVUS reveals any of the following:
· Embryonic crown-rump length ≥7 mm and no heartbeat.
· Mean gestational sac diameter ≥25 mm and no embryo present.
· No embryo with heartbeat ≥2 weeks after TVUS showed a gestational sac without a yolk sac.
· No embryo with heartbeat ≥11 days after TVUS showed a gestational sac with a yolk sac.
For evaluation and management of a woman with pregnancy of unknown location when TVUS reveals no intrauterine fluid and no obvious adnexal abnormalities:
· A single hCG assessment, regardless of level, does not reliably determine a pregnancy's location or viability (this is because hCG levels in women with nonviable IUPs, viable IUPs, and EPs overlap substantially).
· A single hCG level 3000 mIU/mL should not elicit treatment for presumed EP.
· A single hCG ≥3000 mIU/mL indicates that viable IUP is possible but unlikely. At least one additional hCG level should be measured before initiating treatment for EP.
For pregnant women in whom TVUS has not been performed:
· Clinicians should recognize that hCG levels in women with EP are highly variable (but often 1000 mIU/mL), and that hCG level does not predict probability of EP rupture. For high clinical suspicion of EP, TVUS should be performed even if hCG level is low.
Comment: Incorrectly diagnosing an early pregnancy of uncertain viability or location has led some clinicians to prescribe methotrexate for suspected ectopic pregnancy in women later found to have viable intrauterine pregnancies. The authors emphasize that, in hemodynamically stable women, the risk associated with collecting additional data for several more days is limited and will likely allow definitive diagnosis of pregnancy location and viability using the criteria in these guidelines.
Citation(s): Doubilet PM et al. Diagnostic criteria for nonviable pregnancy early in the first trimester. N Engl J Med 2013 Oct 10; 369:1443