Evaluation for intrauterine pregnancy versus ectopic pregnancy in a hemodynamically stable patient

TVUS: transvaginal ultrasound; hCG: human chorionic gonadotropin; mIU: milli-international unit; IUP: intrauterine pregnancy.
* Ectopic pregnancy can be life threatening; patients who are hemodynamically unstable or in whom a ruptured ectopic pregnancy is suspected are managed differently and should be evaluated in the emergency department.
¶ Patients with an undesired pregnancy may be able to forgo follow-up testing with TVUS and serum hCG and undergo expedited active management (eg, diagnostic uterine aspiration [with laparoscopy if an adnexal mass is present], methotrexate).
Δ Nondiagnostic findings on ultrasound include no findings in the uterus or adnexa, a potential gestational sac in the uterus with no yolk sac or embryo (ie, pseudosac), or an adnexal mass with no yolk sac or embryo.
◊ We use a discriminatory zone of 3510 mIU/mL as the level above which a gestational sac should be visualized by TVUS if an IUP is present.
§ Rare etiologies of elevated hCG include heterotopic pregnancy and gestational trophoblastic tumors (hCG levels are usually very high and can reach >100,000 mIU/L).
¥ TVUS will show an intrauterine gestational sac with a yolk sac or embryo.
‡ Findings suspicious for ectopic pregnancy include a complex inhomogenous extraovarian adnexal mass or an extraovarian adnexal mass with an empty gestational sac (sometimes referred to as a "tubal ring"). Findings diagnostic of an ectopic pregnancy include a gestational sac with a yolk sac or embryo, with or without a heartbeat, outside of the uterine cavity.
† Patients with clinical suspicion for ectopic pregnancy (eg, patients with risk factors for ectopic pregnancy) and an hCG >200 mIU/mL are not candidates for expectant management and should be managed with surgery or methotrexate.
** In rare cases, an ectopic pregnancy can be present alongside an IUP; this is known as a heterotopic pregnancy.