Bowel obstruction

Bowel obstruction is due to mechanical obstruction (partial or complete) of the bowel lumen and/or peristaltic failure. Can be complex to manage and requires specialist advice. Bowel obstruction should be managed in a multidisciplinary way and it may be relevant to seek the views and review of a surgical team (if surgery is contemplated), oncologists and palliative care (dependent on the setting).

Presentation depends on the level, type and duration of bowel obstruction but may include:

• constipation
• intermittent nausea, often relieved by vomiting undigested food
• worsening nausea and/or faeculent vomiting (as obstruction progresses and small bowel contents are colonised by colonic bacteria)
• continuous abdominal pain due to tumour and/or nerve infiltration (for example coeliac plexus involvement)
• colic (in mechanical obstruction); altered bowel sounds
• abdominal distension (may be absent in gastro-duodenal obstruction or patients with extensive peritoneal spread)
• faecal incontinence.

• Prioritise assessment for care within a managed care setting.
• Exclude faecal impaction from history, rectal examination, abdominal X-ray. Can complicate or mimic any type of bowel obstruction.
• Some patients with a localised obstruction can benefit from surgery.
• Assess each patient on the basis of their clinical condition, likely benefits/risks and patient preferences.

Factors that may suggest surgery is not indicated

• Diffuse intra-abdominal cancer seen at previous surgery, or shown radiologically.
• Diffuse, palpable intra-abdominal masses.
• Massive ascites which recurs rapidly after drainage.
• High obstruction involving the proximal stomach.
• Non-symptomatic but extensive metastatic disease outside the abdomen.
• Frail or elderly patient with poor performance status or nutritional status.
• Previous radiotherapy to the abdomen or pelvis.
• Small bowel obstruction at multiple sites. 

General

• Frequent mouth care is essential.
• In the acute phase (2 to 3 days) conservative management and watchful waiting may be appropriate - the bowel may be rested, nil by mouth +/- nasogastric (NG) tube.
• As this is a mechanical problem avoid overuse of anti-emetics as these can make the patient sleepy and potentially lead to aspiration.
• Offer ice to suck, small amounts of food and drinks as wanted. Low fibre diet.
• If the patient is dehydrated and not dying, intravenous (IV) rehydration may be appropriate initially.
• Subcutaneous (SC) fluids may be required for longer-term management of symptomatic dehydration or for a patient not wanting hospital admission. Hydration of 1 to 1.5 litres/ 24hours may reduce nausea but more fluid than this can result in increased bowel secretions and worsen vomiting.
• Laxatives +/- rectal treatment for constipation.

Interventional treatment

• Stenting (gastric outlet, proximal small bowel, colon) or laser treatment can palliate localised obstruction.
• NG tube may be appropriate to control vomiting initially; try to avoid long-term use. However, for some patients, an NG tube may be preferable and more manageable at home than faecal vomiting.
• Venting gastrostomy in a fit patient with gastroduodenal or jejunal obstruction and persistent vomiting may relieve symptoms.
• Total parenteral nutrition (TPN) is only appropriate for a very small group of patients with a longer prognosis. Refer to specialist advice. A specific review date should be set which is discussed in advance with the patient prior to commencing TPN.

Peristaltic failure

• May be due to autonomic neuropathy or intra-abdominal carcinomatosis. Partial obstruction, reduced bowel sounds, no colic.
• Stop medication reducing peristalsis (cyclizine, hyoscine, 5HT3 antagonists, amitriptyline).
• Use a prokinetic antiemetic, for example SC †metoclopramide 30mg to 120mg/24hrs; stop if colic develops. Caution in use of prolonged higher doses, monitor for extrapyramidal side effects.
• Laxatives are often needed. Refer to constipation guideline.
• Balance analgesic needs against the risk of poor oral absorption. If a syringe pump is considered in the first instance then morphine or diamorphine would be considered in the first instance.
• However in the longer term a fentanyl patch may provide a less invasive approach.
• Fentanyl patch for controlling stable, moderate to severe pain in patients with/or at risk of peristaltic failure is less constipating than morphine or oxycodone.

Mechanical obstruction

• Target treatment at the predominant symptom(s).
• Laxatives (+/- rectal treatment) to treat/ prevent co-existent constipation. Laxido (if volume of fluid is tolerated) is effective. †Docusate sodium is an alternative. Avoid stimulant laxatives (senna, bisacodyl, danthron) if patient has colic. Stop all oral laxatives in complete obstruction.
• †Dexamethasone (6mg to 16mg) parenterally for 4 to 7 days may reverse partial obstruction. Refer to †Dexamethasone guideline for administration guidance.

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• When using sedating medication, consider starting at lower doses.
• Most patients need an SC infusion of medication as oral absorption is unreliable.
• Review treatment regularly; symptoms often change and can resolve spontaneously.
• Do not combine anticholinergic antiemetics (cyclizine, hyoscine) with metoclopramide. Caution in use of prolonged higher doses of metoclopramide, monitor for extrapyramidal side effects. Refer to related guidelines for Subcutaneous medication, Nausea and vomiting, Levomepromazine.

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