Diagnosis of early pregnancy loss with transvaginal ultrasound*

IUP: intrauterine pregnancy; CRL: crown-rump length; MSD: mean gestational sac diameter.

* Early pregnancy loss generally applies to pregnancy in the first trimester (ie, up to 12 6/7 weeks' gestation).

¶ The sequential development of pregnancy structures visible with ultrasound imaging in normal early pregnancy include gestational sac (in gestational week 4), yolk sac (in week 5), and embryonic pole (5 6/7 weeks), with cardiac activity (in week 6). Crown-rump length is a longitudinal measurement of the embryonic pole. Gestational age based on last menstrual period may be inaccurate; a detailed discussion of determining gestational age with ultrasound findings is presented in related UpToDate content.

Δ Discussion of the evaluation and management of ectopic pregnancy, including heterotopic pregnancy, and pregnancy of unknown location are presented in related UpToDate content.

◊ For patients who desire expedited treatment of pregnancy loss and who accept a small chance of interrupting a potentially viable pregnancy, definitive treatment for pregnancy loss can be considered with the following caveats:

• The ultrasound was performed and interpreted by a highly skilled sonographer/sonologist.

• and

• The patient has a clear understanding of a possible false-positive result.

§ Patients with CRL <5 mm are advised to repeat imaging in 7 to 10 days to assess for embryonic growth and cardiac activity. Patients with MSD <16 mm are advised to repeat imaging closer to 14 days (rather than 7 to 10 days) to increase the chance of visualizing a live pregnancy.