Bowel obstruction, malignant

Definition

Malignant bowel obstruction - mechanical or functional obstruction of the GI tract from intra-abdominal/pelvic malignancy or its treatment effects, often at multiple levels and frequently inoperable given the extent of underlying disease

Most commonly complicates advanced ovarian and colorectal cancer, and can be partial or complete, single-level or (commonly) multi-level

Obstruction may be mechanical (direct tumour occlusion, extrinsic compression, or adhesions from prior surgery) or functional/pseudo-obstruction (malignant infiltration of the bowel wall/mesentery impairing motility without a discrete mechanical block) - the two can coexist, and distinguishing them affects management options

Presents with colicky abdominal pain, nausea/vomiting (which can become faeculent with prolonged/complete obstruction), abdominal distension, and altered bowel habit (obstipation, or paradoxical overflow diarrhoea in partial obstruction)
CT abdomen/pelvis characterises the level(s), completeness, and likely cause of obstruction, and assesses surgical feasibility

Surgery is considered where a single, accessible obstruction level exists in a patient with reasonable performance status and expected benefit outweighing surgical risk - but is often not appropriate in diffuse peritoneal disease or poor performance status
Medical/symptom-focused management (the more common approach in advanced disease): antiemetics (choice depends on mechanism - a prokinetic if partial/functional obstruction without complete mechanical block, a non-prokinetic if complete obstruction, since a prokinetic could worsen colic against a fixed obstruction), analgesia (opioids for background pain, antispasmodics such as hyoscine butylbromide for colic), and antisecretory agents (hyoscine butylbromide, octreotide) to reduce GI fluid accumulation and associated vomiting
Corticosteroids as an adjunct to reduce peritumoural oedema (see corticosteroids in bowel obstruction)
Venting gastrostomy can provide effective symptom relief in selected patients with persistent vomiting despite medical management, avoiding the need for a long-term nasogastric tube

Ovarian cancer, colorectal cancer, peritoneal carcinomatosis, prior abdominal/pelvic surgery (adhesion-related component)

Malignant bowel obstruction in advanced, inoperable disease is often managed as a chronic, fluctuating symptom rather than an acute surgical emergency - the goal shifts to optimal symptom control (often allowing some oral intake even with an ongoing partial obstruction) rather than aiming for complete resolution

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