History and exam

Key diagnostic factors

common

constipation/failure to pass flatus or stool

Due to distal interruption of faecal flow. Constipation is not always absolute. Some patients may still pass flatus and small amounts of stool.[15]

risk factors

Key risk factors include the following.

  • Previous abdominal surgery

    • This can lead to intra-abdominal adhesions that may cause obstruction. Open abdominal surgery carries a greater risk of intra-abdominal adhesion-related small bowel obstruction compared with laparoscopic surgery.[5][6][7] A history of previous episodes of bowel obstruction due to adhesions is a risk factor for adhesive bowel obstruction.[14] 

  • Hernias

    • Inguinal, ventral incisional, umbilical, and parastomal hernias can lead to incarceration and intestinal obstruction.

  • Crohn's disease

    • Crohn’s disease can lead to the formation of an inflammatory phlegmon or fibrotic strictures that may obstruct the intestine. Crohn's strictures may give symptoms of intermittent obstruction.

  • Intestinal malignancy

    • A malignancy can cause an intestinal blockage, either from primary tumour or from metastases.

  • Appendicitis

    • This can lead to obstruction of the intestine due to the formation of an inflammatory phlegmon/abscess.

  • Foreign-body ingestion

    • This can cause a mass effect in the intestinal lumen and prevent the passage of intestinal contents.

  • Gallstone ileus

    • A mechanical obstruction results from a large gallstone passing through a cholecystoduodenal fistula.

    • Less than 1% of cases of intestinal obstruction are derived from this aetiology.[17] 

  • Malrotation of the gut

    • This is common as a paediatric condition, but rarely presents in adulthood.[18]

  • Intussusception

    • Occurs infrequently in adults and differs from childhood intussusception in its presentation and aetiology.[19] 

  • Volvulus

    • A rare cause of an acute abdomen in adults.[20]

intermittent abdominal pain

Described as cramping, intermittent, and severe.

vomiting

Vomiting may occur after the onset of pain; the patient may be bilious.

Urgently manage any patient with faeculent vomiting. This suggests established obstruction that is relatively unlikely to settle without surgical intervention. It is also an indication that significant fluid shifts, dehydration, and nutritional insufficiency may be present.

abdominal distention

Abdominal distention is a common sign, though it may be absent with more proximal obstruction.[15]

abdominal tenderness

Examine the patient’s abdomen. Palpate for any tenderness.[4][14] 

  • Localised or generalised guarding may indicate impending or actual perforation bowel and are indications for urgent surgery.[4][14] 

abdominal mass

Examine the patient’s abdomen. Palpate for any mass or hernia.[4][14] 

  • If you suspect a hernia, look for significant skin changes at the site, such as discoloration or erythema.

  • Look for scars indicative of prior surgery.

  • Localised or generalised guarding may indicate impending or actual perforation bowel and are indications for urgent surgery.[4][14] 

palpable rectal mass

Palpate for a mass and look for any blood.

peritonitis

Signs of severe systemic illness or clinical deterioration, such as fever, leukocytosis, tachycardia, metabolic acidosis, or continuous pain, may indicate peritonitis is present.[11] The key physical sign is the presence of localised or generalised guarding.

Other diagnostic factors

common

pyrexia

A fever indicates a systemic inflammatory response, which may be a sign of potential ischaemia, strangulation, or an obstructed hernia, all of which are indications for early surgery.[4]

nausea (with or without vomiting)

Nausea or vomiting may occur after the onset of pain; the patient may be bilious. Urgently manage any patient with faeculent vomiting.[4][14] 

tachycardia

A sign of potential peritonitis, ischaemia, strangulation, or an obstructed hernia, all of which are indications for early surgery.[4] 

uncommon

groin swelling

Examine the groin for the presence of irreducible and/or strangulated hernias. It is easy to miss a small obstructing (i.e., femoral) hernia in an obese patient, underlining the importance of an early abdominal computed tomography scan in such patients.

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