Malignant Bowel Obstruction

Malignant bowel obstruction (MBO), especially of abdominal or gynecological origin, is common in patients with advanced cancer. MBO is defined as:

• clinical evidence of bowel obstruction

• obstruction distal to the Treitz ligament

• the presence of primary intra-abdominal or extra-abdominal cancer with peritoneal involvement

• the absence of reasonable possibilities for a cure.

Symptoms

Common symptoms in MBO include:

• vomiting

• nausea

• colicky pain

• continuous pain

• dry mouth

• constipation

• overflow bacteria

Diagnostic Workup

• Plain abdominal radiographs are sensitive for high-grade obstruction and are quick and easily accessible.

• Contrast-enhanced abdominal CT can detect low-grade obstructions as well as quantitate disease burden and other clinical factors (e.g., bowel ischemia).

• Routine bloodwork can rule out metabolic derangement (electrolytes, extended electrolytes); include CBC, lactate, and renal function.

Management

The management of MBO varies considerably among patients depending on disease severity, biology of the underlying malignancy, prognosis, and institutional practices. Potential therapeutic interventions include:

• Palliative surgery (e.g., bowel resection, diversion ileostomy, intestinal bypass, lysis of adhesions, removal of tumor). The patient’s overall prognosis, nutritional status, and disease burden should be taken into account prior to surgery.

• Endoscopic or interventional radiology procedures (e.g., stenting or placement of venting gastrostomy tubes)

• Medical management, with or without surgical intervention, including:

  • Bowel rest and nasogastric decompression (NGT)

  • Pain control: opioids may be needed for pain control but can reduce bowel motility.

  • Antiemetics: Agents to be considered are the antipsychotics haloperidol, olanzapine, and prochloperazine and the 5-HT₃ antagonists granisetron and ondansetron (noting that the 5-HT₃ antagonists can be constipating).

  • Prokinetic drugs: Metoclopramide and domperidone can be helpful for management of partial MBO but should be avoided in complete obstruction.

  • Antisecretory drugs: Somatostatin analogues (including octreotide and lanrotide) are supported by the greatest body of evidence and can reduce nausea and vomiting by reducing gastrointestinal secretions and colic. Other agents to be considered are the anticholinergics (hyoscine butylbromide and scopolamine).

  • Glucocorticoids: In addition to having antiemetic properties, these agents may increase the rate of spontaneous resolution of MBO by reducing inflammation.

  • Oral osmotic laxatives: These agents should be considered in the setting of partial MBO but avoided in complete MBO.

  • There are no randomized data supporting the use of cannabis.

• Nutrition:

  • Total parenteral nutrition (TPN) is controversial in this setting and should be reserved only for patients with preserved functional status, indolent disease biology, and favorable prognosis.

  • Dietary modifications upon resolution of MBO include a low-fiber diet.

Advanced care planning, with inclusion of palliative medicine teams, should be undertaken in patients presenting with MBO.