Def: mechanical obstruction of either the small bowel (SBO) or large bowel (LBO). Ileus/Pseudo-obstruction may occur after any general anaesthetic.
Sx: abdominal colic, vomiting (may be faecal with severe obstruction or with colonic fistula to proximal gut) and constipation without passage of wind.
SBO – vomiting occurs earlier, pain is higher in abdomen and there is less distension
Sg: abdominal tenderness and distension with increased bowel sounds (tinkling bowel sounds indicate perforation), except if the cause is ileus, in which case there is no pain and absent bowel sounds. Need to perform hernia exam/DRE.
Marked tenderness (peritonism – rebound tenderness specifically) suggests strangulation, requiring immediate surgery (may also be fever).
Causes: SBO – postoperative adhesions (commonest cause in the young. 60% - mostly with appendicectomies, colorectal surgery, gynaecological procedures and upper GI procedures), malignancy, Crohn’s disease, hernias.
LBO – malignancy, stricture (diverticular or ischaemic), volvulus, incarcerated hernia, intussusception, impaction, ileus, gallstone ileus. Can also be due to pseudo-obstruction/Ogilvie syndrome where there is no anatomical explanation for obstruction.
Classification: Simple – one obstruction point without vascular compromise.
Closed-loop – obstruction at two points (e.g. volvulus) forming loop of bowel. Greater risk of perforation.
Strangulated – blood supply is compromised.
Ix: AXR – most important diagnostic tool. Air fluid levels within the bowel, with dilation of bowel wall proximal, indicate obstruction. Need to also determine portion of bowel affected, if there are circular folds then it is SBO, if there are none then it is LBO (as haustra expand).
Sigmoid volvulus can be seen on AXR as a U shape of bowel (coffee bean appearance).
Bloods – FBE (↓ Hb may suggest iron deficiency anaemia, ↑WCC may be present with constipation/obstruction/apppendicitis), check for volume state and electrolyte balance on UEC, Group and Hold for surgical intervention.
Urinalysis to exclude UTI, if suspected.
CXR – if unable to see on AXR, may be needed to exclude perforation.
CT Abdo – while not typically ordered for obstruction, can be used to exclude strangulation, especially in a patient with septic signs.
Mx: treatment depends on cause (e.g, surgery for tumours and adhesions, treatment of inflammatory bowel), otherwise there is general treatment of faecal impaction.
Initial – fluid resuscitation, electrolyte imbalance correction, bowel decompression (NGT suction), analgesia, anti-emesis. Cures most cases within 3 days. May need some enemas or manual disimpaction.
Surgery – if strangulated or complicated or if patient exhibits fever, ↑WCC, tachycardia, and/or increasing pain. May require gut resection if strangulated and gangrenous. Mostly needed for LBOs.
Pseudo-obstruction: treated with Neostigmine 2mg over 3-5min.
Px: generally good outcomes, especially with surgery. Complications include perforation, peritonitis, sepsis, (if due to abscess), anastamotic leakage (if resected), dehydration, death.