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Ultrasonography of pregnancy of unknown location

Tejas S Mehta, MD, MPH
Section Editors
Howard T Sharp, MD
Deborah Levine, MD
Deputy Editor
Sandy J Falk, MD, FACOG


Pelvic pain or vaginal bleeding during the first trimester of pregnancy is a common presentation to clinicians in the office or emergency department. Determining the location of the pregnancy is the first priority in the evaluation of these women, with the exception of hemodynamic stability. Whether the pregnancy is intrauterine or ectopic (and the precise extrauterine location) guides the remainder of the evaluation and management. Early diagnosis of ectopic pregnancy is important to avoid adverse sequelae of this potentially life-threatening condition. Pelvic ultrasonography is the most useful imaging modality for these patients.

Sonography of women with pregnancy of unknown location will be reviewed here. General principles of the diagnosis and management of ectopic pregnancy and of obstetric ultrasound are discussed separately. (See "Ectopic pregnancy: Clinical manifestations and diagnosis" and "Ultrasound examination in obstetrics and gynecology" and "Prenatal assessment of gestational age, date of delivery, and fetal weight".)


Ultrasonography (US) is the pelvic/abdominal imaging modality of choice for pregnant women. It does not require the use of potentially harmful ionizing radiation, is readily available, and allows real-time imaging. (See "Diagnostic imaging procedures during pregnancy".)

Magnetic resonance imaging is useful if US is not able to elucidate the location of a pregnancy [1]. Examples of this include differentiating an intrauterine pregnancy (IUP) from a cervical or interstitial pregnancy or elucidating the anatomic relationships of an abdominal pregnancy.

Computed tomography generally has no role in the evaluation of pregnancy of unknown location, due both to its limited resolution of tissue planes and use of radiation.

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Literature review current through: Nov 2017. | This topic last updated: Nov 20, 2015.
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