Questionnaire/history?

Acute:

(Note: often adhesions (40% of all bowel obstruction) or obstructed hernia (12%))

- Sudden onset of severe colicky abdominal pain?

- Early profuse vomiting (high obstruction)?

- Early abdominal distension (low obstruction)?

Acute on chronic:

(Note: often partial colonic obstruction that then completes: cancer (15%), diverticular stricture (unknown incidence), faecal impaction (8%))

- Symptoms and signs of an acute obstruction, but history of a chronic obstruction?

Subacute small bowel obstruction:

(Note: incomplete)

- Presentation over several days?

- Intermittent, less severe pain?

- Intermittent, less severe vomiting?

- Constipation not absolute?

- Distension not marked?

Chronic (large bowel) obstruction?

(Note: initially incomplete, increases slowly, often colorectal or diverticular stricture)

- Symptoms evolved over months (esp in elderly)?

- Weight loss?

- Malnutrition?

High obstruction (eg small bowel)?

- Early vomiting?

--- Vomiting for more than 24 hours?

- Colicky abdominal pain?

- Distension (may be absent)?

Low obstruction (eg colonic)?

- Distension (prominent feature)?

- Abdominal pain (usually present but may be less severe or frequent (esp. in the elderly)?

- Vomiting (may be ascent/occur late)?

--- Vomiting for more than 24 hours?

Diarrhoea (in the early stage)?

Lack of diarrhoea?

Constipation?

- Absolute constipation?

Past medical history?

- Abdominal surgery?

- Pelvic surgery?

(Note: the first 3 years post-surgery are especially high risk for obstructions)

Current medication?

Known drug allergies?

Examination:

Abdominal distention?

(Note: abdominal distension not obvious in obese patients)

Hernial orifices?

Abnormal bowel sounds (‘tinkling’)?

(Note: poor sensitivity and specifity)

Empty rectum (does not exclude obstruction)?

Peritonitis?

(Note: occurs late, after perforation or infarction, so its absence has not diagnostic value)

Investigations:

Abdominal x-ray (sensitivity and specificity low)?

CT abdomen (best)?

Suspected subacute bowel obstruction:

- On-the-day referral to the local surgical team

Resource(s):

BMJ 2021;374:n1765