An acute abdomen refers to a sudden, severe abdominal pain. It is in many cases a medical emergency, requiring urgent and specific diagnosis. Several causes need immediate surgical treatment. The most common cause of acute abdomen was non-specific abdominal pain (NSAP) (33.0%) followed by acute appendicitis (23.3%) and acute biliary disease (8.8%). The pain may just be in one part of the belly or it may affect the entire area. You'll likely also have other symptoms like nausea, vomiting, bloody stool, dizziness, feeling lightheaded, or fever. Most causes of acute abdominal pain are very serious and considered medical emergencies.