Malignant bowel obstruction

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Introduction

Bowel obstruction in malignancy is complex in aetiology

Underlying pathophysiology often involves combination of physical mechanical obstruction plus ileus / motility related issues, usually in patients with disseminated peritoneal metastases

Common causes

Pelvic malignancies, especially ovarian cancer

Gastrointestinal malignancies such as colorectal cancer or pancreas cancer

Clinical features

Often a preceding waxing and waning course of nausea and vomiting with reducing frequency of bowel movements and abdominal distension for a few weeks.

As the illness progresses an obvious mechanical bowel obstruction may develop. See [Features]

Investigations

The appropriate extent of investigations and treatment varies based on how advanced the patients malignancy is as well as his or her wishes.

CT scan

  • May be appropriate if stenting or surgery would be considered
  • Will often distiguish between unifocal (which may be amenable to endoscopic stenting or surgery) versus multi-focal obstructions (which portends a poor prognosis)#

Management

"Pre-Bowel Obstruction"

In patients at high risk of a full blown malignant bowel obstruction who have no abdominal pain but increasing distension, nausea, vomiting and reducing bowel movements:

Metoclopramide 30mg via CSCI over 24 hours
Sodium docusate 200mg twice daily (or an alternative stool softener)
+/- Dexamethasone 8mg daily SC

Clear Malignant Bowel Obstruction

In many patients surgery or stenting is unlikely to be helpful, although for very proximal unifocal lesions or for patients otherwise very fit and healthy it may be worth considereding

Usually malignant bowel obstruction is indicative that a patient is coming into the last few weeks or month of life. A kind but frank discussion about this is usually helpful.

If vomiting and abdominal pain are very severe, consider drainage NG tube, otherwise it may be best to avoid this, especially if a more comfort- based approach to treatment is being considered

Treat vomiting and distension with anti-secretorary agents:

Ranitidine 150mg via CSCI over 24 hours
Octreotide 600mg via CSCI over 24 hours

Treat nausea with an anti-emetic, e.g.

 Haloperidol 2.5mg via CSCI over 24 hours
 + Haloperidol 1mg SC 2-hourly PRN for nausea

Treat abdominal pain with an anti-spasmodic + an opioid, e.g.

Hyoscine butylbromide 60mg via CSCI over 24 hours
A low dose opioid via CSCI over 24 hours and SC PRN 

Also consider dexamethasone 8mg daily SC

If intractable vomiting persists, consider a venting PEG