The term "acute abdomen" defines a clinical syndrome characterized by the sudden onset of severe abdominal pain requiring emergency medical or surgical treatment [1]. A prompt and accurate diagnosis is essential to minimize morbidity and mortality [2]. The differential diagnosis includes an enormous spectrum of disorders ranging from benign self-limited diseases to conditions that require emergency surgery [3]. In a review of approximately 30,000 patients with acute abdomen, de Bombal [4] observed that 28% of patients had appendicitis, 9.7% had acute cholecystitis, 4.1% had small-bowel obstruction, 4% had acute gynecologic disease, 2.9% had acute pancreatitis, 2.9% had acute renal colic, 2.5% had perforated peptic ulcer, and 1.5% had diverticulitis. In one third of patients, no cause could be determined.
The clinical diagnosis of acute abdomen can be challenging because physical examination, clinical presentation, and laboratory examination are often nonspecific and nondiagnostic. Although sonography [5-7] has developed a niche in evaluating the gallbladder in all patients and the appendix in children and women of reproductive age, CT [8-14] has evolved as the premier technique for triaging most patients. CT has earned this role because it can provide a global perspective of the gut, mesenteries, omenta, peritoneum, retroperitoneum, subperitoneum, and extraperitoneum uninhibited by the presence of bowel gas and fat. Helical scanning allows thinner contiguous images to be obtained without increasing radiation exposure and without respiratory misregistration. The rapidity of scanning allows several acquisitions to be obtained during different phases of a single IV contrast bolus.
We describe the practical aspects of optimizing helical CT and emphasize the CT features of common acute abdominal disorders.