Abdominal pain is a very common complaint, and the differential diagnosis is wide, ranging from benign to life-threatening conditions. Life-threatening conditions include a ruptured abdominal aortic aneurysm, mesenteric ischemia, perforation anywhere along the gastrointestinal tract, acute bowel obstruction, acute pancreatitis, peritonitis, ectopic pregnancy, ovarian torsion, and myocardial infarction.
There are three main types of abdominal pain: visceral, parietal, and referred pain. Visceral pain happens when the nerves that run through the walls of an organ get stretched. The pain isn't usually well localized and feels like a dull ache or cramp. Hollow organs cause an intermittent colicky type of pain, whereas solid organs cause a more constant pain.
Sometimes, as a disease evolves, visceral pain can become parietal pain, which is also called somatic pain. That’s the pain that results from irritation to the parietal peritoneal wall. Parietal pain is sharp and can be localized by pointing to a specific spot. Finally, there’s referred pain which is when the brain mistakenly identifies pain as coming from one region like the shoulder when it’s actually coming from a different region like the diaphragm.
Abdominal pain can often be separated into the abdominal area that’s involved. Foregut organs - so the stomach, duodenum, pancreas, and biliary tract - cause epigastric pain. Epigastric pain that’s associated with bloating, abdominal fullness, heartburn, or nausea is called dyspepsia, and it’s generally due to gastroesophageal reflux disease, gastritis, pancreatitis, or peptic ulcer disease - meaning an ulcer of the stomach or duodenum.