Acute abdomen is a clinical scenario marked by severe abdominal pain of acute onset, typically within 24 hours. The differential diagnosis is broad and includes the following: acute appendicitis, acute cholecystitis, acute pyelonephritis, acute diverticulitis, acute pancreatitis, ectopic pregnancy and ovarian torsion (if female), acute peritonitis, bowel obstruction, acute mesenteric ischemia, and abdominal aortic aneurysm (AAA) with rupture. Although all of these conditions are serious, only some of them require urgent surgical evaluation and potentially surgical intervention. For example, an AAA with rupture is a surgical emergency with a high mortality rate whereas acute pyelonephritis rarely requires surgical intervention. Additionally, not all of these conditions will present with physical exam findings of an acute “surgical” abdomen. These exam findings include guarding, rebound tenderness, absent bowel sounds, and abdominal distension. Imaging and a thorough clinical history and physical exam are essential in determining the cause of the acute abdomen. However, in cases of acute mesenteric ischemia, abdominal exam findings may be out of proportion to the degree of pain—in other words, the abdominal exam may not exhibit any of the classic surgical abdominal findings mentioned above, yet the patient will complain of extremely severe abdominal pain. When the lactic acid level is markedly elevated then acute mesenteric ischemia is much higher on the differential.
Medical expert witness specialties involving acute/surgical abdomen include general surgery, emergency medicine, pediatric surgery, pediatric emergency medicine, emergency nursing, radiology, and urgent care.