Uterine Imaging

The uterus is the Latin term for the womb, located between the female pelvis's bladder and rectum. It is a relatively superficial organ that can be imaged using a variety of modalities. Most commonly, ultrasound is the modality used for imaging the uterus. However, magnetic resonance imaging (MRI) comes second to evaluate uterine pathology. Other rarer modalities include hysterosonogram, hysterosalpingogram, and positron emission tomography-computed tomography (PET-CT). Each of these modalities is useful in evaluating different aspects. Modalities to Evaluate the Uterus: Ultrasound. CT/X-ray. MRI. PET-CT. Hysterosonogram and hysterosalpingogram. Imaging in Pregnancy Pregnancy is a special physiological state and requires separate consideration. Imaging in pregnancy is usually by ultrasound (see Image. Uterus Ultrasound, Molar Pregnancy). Clinicians can assess the uterus, gestational product, and ovaries, which are assessable on ultrasound. The fetus can be monitored throughout pregnancy with transabdominal and transvaginal ultrasound (see Images. Transabdominal Long Image of a Normal Uterus and Transvaginal Long Image of a Normal Uterus). The placenta and its variants can also be assessed on ultrasound. MRI imaging of the uterus during pregnancy may be necessary on rare occasions; this is usually to evaluate gestational trophoblastic disease or conditions such as endometriosis. The fetus can also undergo evaluation on MRI. Evaluation of gestational trophoblastic disease (GTN) presents a diagnostic dilemma as gadolinium contrast, useful in assessing GTN, is usually not administered during pregnancy. Gadolinium-based contrast agents can cross the placenta. Though the deleterious effects on the fetus remain unproven, it is considered to be a class C drug and is usually avoided in pregnant patients unless necessary. Hence, a noncontrast MRI is the norm for pregnant patients. CT and PET-CT for assessing uterus or gynecological malignancies are associated with ionizing radiation and are contraindicated in pregnant patients. However, depending on the clinical scenario and in special circumstances where a nonionizing modality is unavailable or not useful, CT may be performed, keeping the radiation levels as low as reasonably achievable (ALARA). PET-CT, in particular, uses 18-F-fluorodeoxyglucose, a radiopharmaceutical contraindicated in pregnant patients and crosses the placenta. However, the study may be performed if the medical benefits outweigh the risks.