What is the first line imaging modality of the female pelvis and why?
Common indications for pelvic imaging in a female patient include pelvic pain, pelvic masses, and abnormal bleeding. Ultrasonography (US) is the imaging modality of choice for evaluating the female pelvis because it offers excellent visualization of the pelvic organs. It is also fast, inexpensive, and portable and requires no intravenous or oral contrast material. If US results are inconclusive, magnetic resonance imaging (MRI) may be obtained for further evaluation. Computed tomography (CT) is generally reserved for emergent settings including trauma, hemodynamic instability, or acute lower abdominal or pelvic symptomatology when the differential diagnosis is broad, or for evaluation of patients with gynecologic malignancy. Positron emission tomography (PET) in combination with CT is most often performed for evaluation of suspected or known pelvic malignancy.