A 12-year-old premenarchal girl presented after 2 days of abdominal pain. She had been seen several times over the previous 6 months for similar symptoms. Her pain had become constant, severe, and sharp, and nonprescription analgesics no longer provided relief. The pain was predominantly in her periumbilical region and radiated to the left lower quadrant. She reported one episode of diarrhea but no nausea, vomiting, anorexia, or fevers. She had no history of recent travel, contact with sick people, dietary changes, or new psychosocial stressors. A review of systems was positive for intermittent constipation and occasional dysuria. She was not sexually active.

Physical examination revealed a tender, palpable mass protruding against her abdominal wall. Computed tomography of the abdomen and pelvis identified the mass as the uterus and vagina, which were both markedly distended with fluid (Figure 1). Magnetic resonance imaging confirmed single uterine and vaginal cavities without abnormal divisions. The cervix and ovaries appeared normal (Figure 2 and Figure 3).

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