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Pathophysiology and management of malignant bowel obstruction

Chapter:
Pathophysiology and management of malignant bowel obstruction
Author(s):

Carla Ripamonti

and Sebastiano Mercadante

DOI:
10.1093/med/9780198570295.003.0069

Malignant bowel obstruction (MBO) is a complex problem occurring particularly in cancer patients with advanced gynaecological and gastrointestinal cancer. Although it may develop at any time in the disease, it occurs most frequently at the advanced stage, with the highest incidence ranging from 5.5 to 42 per cent in ovarian carcinoma. Bowel obstruction occurs in 4.4–24 per cent of patients with colorectal cancer(17). Breast and lung cancer and melanoma are the most frequent extra-abdominal primaries causing bowel obstruction, ranging from 3–15 per cent of cases. Different clinical settings, variation in admission criteria of individual palliative care units or diagnosis parameters, or clinical evaluation may explain the difference in incidence(810).

MBO may be a presenting feature of intra-abdominal malignancy or a feature of recurrent disease or other pathology in patients with a history of malignancy. The aetiology may be benign in 10–48 per cent of cases at operation, caused by adhesions or radiation enteritis, or malignant with single site, multiple site, or diffuse disease. MBO can be at a single site or multiple sites, partial or complete, and occurs in the small intestine more commonly than the large intestine.

Primary cancer, relapse after surgery, chemotherapy or radiotherapy, associated pathologies, and diffuse carcinomatosis may cause bowel obstruction with different mechanisms(11). Such phenomena are often concomitant. The enlargement of the primary tumour or recurrence of abdominal masses, fibrosis, or adhesions may produce extrinsic occlusion of the lumen. Polypoidal lesions or annular narrowing due to dissemination may cause an intraluminal occlusion of the lumen. Infiltration of the intestinal muscles or superimposed inflammation may produce intramural occlusion of the lumen. Intestinal motility disorders due to a deranged extrinsic neural control of viscera may produce delay in intestinal transit, resulting in a clinical picture similar to bowel obstruction, namely, pseudo-obstruction. Concomitant diseases, such as diabetes, para-neoplastic syndromes, or previous gastric surgery, may contribute to dysmotility of this kind.

Constipation, due to illness and/or to drugs such as anticholinergics and opioids, is a frequent concomitant factor, as pain due to opioid-induced constipation, wrongly treated with increased doses of opioids, may result in faecal impaction producing signs of bowel obstruction(12).

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