Acute abdomen and peritoneal irritation !

Syndrome

Severe, recent abdominal pain that may need urgent surgery; the exam looks for signs that the peritoneum is inflamed.

Updated 2026-11-01

See it in 3D: Peritoneum · Appendix · Gallbladder · Pancreas · Sigmoid colon · Greater omentum

What it is

An acute abdomen is abdominal pain of recent onset (hours to a few days) that demands ruling out a surgical or serious cause. Peritoneal irritation is its most important finding: it means the inflammation has reached the parietal peritoneum. Recognizing it at the bedside sets the urgency of imaging and of a surgical review.

Key findings

Pained facies, guarded posture and stillness; or restlessness in colic.
Fever and tachycardia; hypotension and cold skin in sepsis or hemorrhage.
Guarding, generalized rigidity and rebound tenderness.
Reduced or absent bowel sounds in generalized peritonitis.
Named signs that point to the organ: Murphy, McBurney, Rovsing, psoas, obturator, Cullen and Grey Turner.
The hernial orifices are always examined, and a rectal and pelvic exam are considered.

Pathophysiology

Visceral pain: distension, spasm or ischemia of a hollow organ stimulates autonomic fibers that enter the cord at several levels, so the pain feels diffuse and midline (epigastric, periumbilical or hypogastric).
Parietal pain: once inflammation touches the parietal peritoneum, which has segmental somatic innervation, the pain localizes right over the organ involved.
That shift explains the classic migration of appendicitis pain: first periumbilical (visceral), then in the right lower quadrant (parietal).
Referred pain: irritation of the diaphragm (subphrenic blood or pus) can be felt in the shoulder through the phrenic nerve roots.
Reflex contraction of the abdominal muscles protects the inflamed peritoneum; it starts voluntary and becomes involuntary and diffuse.

Common causes

Right lower quadrant: acute appendicitis.
Right upper quadrant: acute cholecystitis, cholangitis.
Epigastric pain radiating like a belt to the back: acute pancreatitis; sudden diffuse pain with rigidity: perforated peptic ulcer.
Left lower quadrant in an older adult: diverticulitis.
Colicky pain with vomiting and distension: bowel obstruction.
Causes not to miss: ruptured ectopic pregnancy, abdominal aortic aneurysm, mesenteric ischemia and extra-abdominal causes such as inferior myocardial infarction or lower-lobe pneumonia.

Tests that confirm it

Pregnancy test in people of reproductive age who can be pregnant.
Blood count, lipase, liver tests and urinalysis as the suspicion dictates.
Ultrasound (gallbladder, appendix in children and pregnancy, pelvis) or contrast CT in adults; an upright chest X-ray looks for free air under the diaphragm.

Test yourself

Think of the answer, then tap the question to see it.

Why does appendicitis pain start around the umbilicus and then move to the right lower quadrant?

At first the distended appendix causes visceral, diffuse periumbilical pain; when inflammation reaches the somatically innervated parietal peritoneum, the pain localizes to the right lower quadrant.

What separates voluntary guarding from involuntary rigidity?

Voluntary guarding eases when the patient relaxes or is distracted; involuntary rigidity persists because it is a reflex to an inflamed peritoneum and suggests peritonitis.

What does very severe abdominal pain with a soft, barely tender abdomen suggest?

Pain out of proportion to the exam, especially in an older adult with atrial fibrillation or vascular disease, suggests acute mesenteric ischemia.

In what order is the abdomen examined, and why is the painful area palpated last?

Inspection, auscultation, percussion, palpation; palpating last avoids altering bowel sounds, and leaving the painful area for last keeps pain-guarding from blocking the rest of the exam.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Abdominal Pain | MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026); Peritonitis: MedlinePlus Medical Encyclopedia (MedlinePlus, U.S. National Library of Medicine, 2026); Appendicitis | MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026).

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Representative model, for educational purposes only.