A 49-year-old premenopausal woman presented with acute onset of lower abdominal pain. Physical examination revealed her abdomen was distended and nontender. Her white blood cell count and serum markers for ovarian cancer were normal (alpha-fetoprotein level, 1.6 microg/L; Ca-125 level, 15 U/mL; beta-human chorionic gonadotrophin level < 2 IU/mL). She had no important medical history; in particular, she had no history of malignancy. She denied having any chest symptoms; in particular, she denied experiencing chest pain, cough, or dyspnea. She had stopped smoking at the age of 40 years after having smoked for a total of 20 pack-years. A computed tomographic (CT) examination of the abdomen and pelvis was performed. Helical CT was performed with 150 mL of intravenous contrast material (iohexol, Omnipaque; Amersham Healthcare, Cork, Ireland) and 750 mL of oral contrast material (diatrizoate sodium, Hypaque; Amersham Health, Princeton, NJ). CT sections were 5 mm thick and were acquired from the top of the diaphragm through the ischial tuberosities with a rotation time of 13.5 seconds per rotation and use of a LightSpeed 16 CT scanner (GE Medical Systems, Milwaukee, Wis).