CT of the mesentery, omentum, and peritoneum in children.

Primary abnormalities of the peritoneum are rare in children. However, there is frequent secondary involvement of the peritoneal cavity and its specialized folds, the mesentery and omentum, in the presence of infectious, neoplastic, and traumatic conditions that originate at other sites in the abdomen or pelvis. Computed tomography (CT) is usually the modality of choice for evaluation of complex abdominal or pelvic pathologic conditions. Peritoneal cavity abnormalities include peritoneal fluid, pneumoperitoneum, and hemoperitoneum; peritoneal abscesses and peritonitis; metastases; and bladder or bowel rupture and solid organ injury. Mesenteric and omental abnormalities include an increase in or infiltration of mesenteric and omental fat; mesenteric lymphadenitis; mid-gut malrotation and bowel herniation; a variety of infections; metastases, lymphoma, and lymphangioma; and mesenteric injury. Knowledge of the spectrum of abnormalities that involve the mesentery, omentum, and peritoneal cavity and the characteristic CT appearances of these abnormalities is essential for improved diagnosis of these conditions.