Imaging of the female perineum in adults.

The female perineum is a diamond-shaped structure inferior to the pelvic diaphragm and between the symphysis pubis and coccyx. The perineum is divided into the anterior urogenital triangle and the posterior anal triangle; the vulva represents the external genitalia. A wide array of diseases affect the female perineum in adults. Vulvar trauma, infection (including Fournier gangrene), developmental lesions, and thrombophlebitis can be investigated with various imaging modalities; vulvar malignancies are best imaged with magnetic resonance (MR) imaging to identify local-regional extent of disease. MR imaging is also the modality of choice for imaging of the distal urethra, although imaging of a urethral diverticulum also includes voiding cystourethrography and ultrasonography. The distal vagina at the level of the introitus is best imaged with MR imaging for assessment of Bartholin gland cysts and malignancies. Diseases encountered in the anus include anal carcinoma, fistula-in-ano, and anovaginal fistula, which can all be imaged with various modalities offering different sensitivities and fields of view. Lastly, musculoskeletal neoplasms affecting the perineum and vulva include mesenchymal, lipomatous, nerve sheath, and osseous neoplasms. These neoplasms can be imaged with both computed tomography and MR imaging, although the latter provides higher soft-tissue contrast and greater anatomic detail for diagnosis and determination of the extent of necessary surgery. Familiarity with the anatomy of the female perineum and appropriate selection of imaging modalities facilitate prompt and accurate diagnosis and treatment.