There are different types of abdominal pain depending on the structures involved.

1. Visceral Pain comes from the organs within the abdominal cavity (which are called the viscera). The viscera’s nerves do not respond to cutting, tearing, or inflammation. Instead, the nerves respond to the organ being stretched (as when the intestine is expanded by gas) or surrounding muscles contract. Visceral pain is typically vague, dull, and nauseating. It may be hard to pinpoint.
2. Somatic Pain comes from the membrane (peritoneum) that lines the abdominal cavity (peritoneal cavity). Unlike nerves in the visceral organs, nerves in the peritoneum respond to cutting and irritation (such as from blood, infection, chemicals, or inflammation). Somatic pain is sharp and fairly easy to pinpoint.
3. Referred Pain is pain that is felt in an area that is distant from the source.

Abdomen pain, can be acute in onset and short in duration, or may be chronic of long duration

Common causes of acute abdomen pain are:

1. Acute appendicitis
2. Cholecystitis due to gall bladder stones
3. Common bile duct stones
4. Acute pancreatitis
5. Perforated peptic ulcer
6. Intestinal obstruction
7. Intestinal perforation
8. Mesentric vascular ischemia
9. Diverticulitis
10. Renal and ureteric stones and pyelonephritis
11. Metabolic such as diabetic ketoacidosis, uremia, porphyria
12. Gynecological causes such as ectopic pregnancy, abortion, ovarian tumors
13. Ruptured Abdominal Aortic Aneurysm

Causes of chronic pain abdomen are:

1. Functional dyspepsia-Indigestion and bloating
2. Irritable bowel syndrome
3. Peptic ulcer disease
4. Ulceration in small or large intestine
5. Chronic pancreatitis
6. Chronic cholecystitis
7. Abdomen tuberculosis
8. Inflammatory bowel disease (Ulcerative colitis and Crohn’s disease)
9. Fluid in peritoneal cavity due to tuberculosis, pancreatitis or malignancy
10. Tumor of stomach, intestine, liver, and pancreas
11. Neurogenic causes – Abdominal migraine and Abdominal epilepsy
12. Mesenteric panniculitis

Treatment of pain depend upon the cause of pain, patient with acute severe pain abdomen should be immediately brought to medical attention, so that exact diagnosis can be established with proper investigations.

Chronic pain abdomen is mostly due to functional disorders like Functional dyspepsia and irritable bowel syndrome, which are diagnosed once the organic causes are ruled out with proper investigations.