Question

Which clinical feature best differentiates mechanical small intestinal obstruction from paralytic ileus?

• A. Colicky pain
• B. Tachycardia
• C. Abdominal distension
• D. Vomiting

Hint:

Bowel peristalsing against a block = cramps; paralysed bowel is silent.

Answer 1

The Correct Option is A

Step 1: Define the two conditions. Mechanical small bowel obstruction is a physical blockage against which the bowel actively peristalses. Paralytic (adynamic) ileus is failure of peristalsis with no mechanical block, so the bowel is silent and atonic.

Step 2: Find the discriminating feature. Because the bowel keeps contracting against a mechanical block, the patient gets colicky (intermittent, cramping) pain with exaggerated, high-pitched (tinkling) bowel sounds. In paralytic ileus the bowel is flaccid, so pain is typically dull/continuous (often painless distension) and bowel sounds are absent.

Step 3: Why the other options do not differentiate. Abdominal distension occurs in both (in ileus it may even be greater and earlier). Vomiting occurs in both. Tachycardia is a non-specific sign of dehydration/sepsis seen in both. Only the character of the pain - colicky - reliably points to a mechanical cause.

Step 4: Conclude. Colicky pain with audible peristalsis indicates mechanical obstruction; its absence with a silent abdomen indicates ileus.

Key fact: Colicky pain (with active/tinkling bowel sounds) distinguishes mechanical small bowel obstruction from the painless, silent abdomen of paralytic ileus.