Background    Malignant bowel obstruction (MBO) is a common oncologic complication. It is most common in ovarian and colon cancer. Symptoms include abrupt onset of nausea, vomiting, and abdominal pain which can be colicky or continuous. MBO has been associated with a prognosis of 3-8 months for operable disease and 4-8 weeks in inoperable cases.  Treatment options include surgical correction, placement of a venting gastrostomy tube, stent placement across the obstructed site, or medical management (see Fast Fact #119 for a discussion of interventional options). Total parenteral nutrition (TPN) may be beneficial in select patients with longer prognoses who may die of starvation rather than the cancer itself (see Fast Fact #190). Still, the need to rely on medical management is common, especially when the patient’s functional status is poor and expected survival is short.  There have been significant advances in the medical management of MBOs, so that many patients can avoid dying with the traditional approach of intravenous fluids and nasogastric tubes (“drip and suck”).

Major drugs 

• Opioids and anti-emetics: usually dopamine antagonists (e.g. haloperidol) can be administered (intravenously or subcutaneously) to relieve pain and nausea.
• Antimuscarinic/anticholinergic drugs (e.g. atropine, scopolamine): are used to manage colicky pain due to smooth muscle spasm and bowel wall distension. In the US, scopolamine can be administered by parenteral (10 mcg/hr IV/SQ continuous infusion) or transdermal (10 mcg/hr) routes but is only available as the hydrobromide salt.  This penetrates the CNS and can lead to delirium.  Glycopyrrolate, a quaternary ammonium antimuscarinic with similar clinical effects to scopolamine, but without the CNS side-effects (dosed at 0.2-0.4 mg IV/SQ q2-4h), may be a viable alternative.
• Gastric acid secretion inhibitors: Histamine-2 antagonists (also called H2 blockers) such as famotidine) and proton pump inhibitors (PPIs) can reduce gastric acid secretion and gastric acid volume.  There is some evidence that H2 blockers may be superior to PPIs.
• Somatostatin analogs:  inhibit the secretion of GH, TSH, ACTH and prolactin, and decrease the release of gastrin, CCK, insulin, glucagon, gastric acid and pancreatic enzymes.  They also inhibit neurotransmission in peripheral nerves of the gastrointestional tract leading to decreased peristalsis and a decrease in splanchnic blood flow.  Octreotide (Sandostatin) is administered as a SQ injection (starting at 50-100 mcg q 8 hours) or as continuous IV or SQ infusion, beginning at 10-20 mcg/hr. Small randomized controlled trials suggest it may be more successful in improving nausea, vomiting, and colic than antimuscarinics for patients with a NG tube.  One case report suggested it may help in partial bowel obstruction as well.  The drug is titrated every 24 hours until nausea, vomiting, and abdominal pain are controlled. A once monthly injection of a long-acting formulation can be used for patients on a stable dose. A more recent randomized controlled trial suggested that dexamethasone with ranitidine may be a more cost-effective alternative to octreotide 600 mcg/day for MBO however.
• Corticosteroids: have been recommended to decrease the inflammatory response and resultant edema, as well as relieve nausea, through both central and peripheral antiemetic effects. A meta-analysis found that 6-16 mg of IV dexamethasone/day decreased symptoms and improved bowel function in 60% of patients.  In fact, a phase III trial suggested little benefit from octreotide in patients already on intravenous ranitidine 200 mg/day and intravenous dexamethasone 8 mg/day.

Minor drugs  Prokinetic drugs (e.g. metoclopramide) may be beneficial if there is a partial MBO. However, if there is total obstruction some advocate the discontinuation of prokinetic agents as they may exacerbate crampy abdominal pain. On the other hand, metoclopramide may inhibit the reverse peristalsis from obstruction and decrease nausea. Olanzapine, an atypical anti-psychotic, blocks multiple neurotransmitters associated with nausea.  It is available in a sublingual route with some published accounts of utility in refractory cases of nausea in cancer.

Care plan    Often medications must be used in combination to achieve clinical goals in MBO. The goal of medical management is to decrease pain, nausea and secretions into the bowel in order eliminate the need for a nasogastric tube and IV hydration.  During the medication titration phase, IV fluids should be restricted to 50 ml/hr.   When NG output is less than 100 cc/day, the NG tube can be clamped for 12 hours and then removed.  Once out, patients are instructed that they may drink and eat, although vomiting may occur.  If a venting gastrostomy tube is already in place, oral intake can be done without fear of vomiting, however, patients are usually instructed to take in foods less likely to clog the gastronomy tubing.  Supplemental parenteral hydration is only indicated if a) patients remain dehydrated despite oral intake, and b) use of hydration to extend life is consistent with the patients’ goals (see Fast Fact #133 and Fast Fact #134).

References 

1. Jatoi A, Podratz KC, Gill P, Hartmann LC. Pathophysiology and palliation of inoperable bowel obstruction in patients with ovarian cancer. J Support Oncol. 2004; 2(4):323-34. PMID: 15357517.
2. Shariat-Madar B, Jayakrishnan TT, Gamblin TC, Turaga KK. Surgical management of bowel obstruction in patients with peritoneal carcinomatosis. J Surg Oncol. 2014;110(6):666–9.
3. Adler DG.  Management of malignant colonic obstruction. Curr Treat Options Gastroenterol. 2005; 8(3):231-237. PMID: 15913512.
4. Shariff F, Bogach J, Guidolin K, et al.  Malignant bowel obstruction management over time: are we doing anything new? A current narrative review.  Gastrointestinal Oncology 2022; 29:1995-2005.
5. Clark K, Lam L, Currow D. Reducing gastric secretions: a role for histamine 2 antagonists or proton pump inhibitors in malignant bowel obstruction? Support Care Cancer. 2009;17(12):1463–8.
6. Ripamonti C, Mercadante S.  How to use octreotide for malignant bowel obstruction. J Support Oncol. 2004; 2(4):357-64. PMID: 15357519. 
7. Mercadante S, Casuccio A, Mangione S. Medical treatment for inoperable malignant bowel obstruction: a qualitative systematic review. J Pain Symptom Manage 2007; 33:217–223.
8. Myers J, Tamber A, Farhadian M. Management of treatment-related intermittent partial small bowel obstruction: the use of octreotide. J Pain Symptom Manage 2010; 39:e1–e3.
9. Currow DC, et al.  Double-blind, placebo-controlled randomized trial of octreotide in malignant bowel obstruction.  J Pain Symptom Manage 2015; 49: 814-21.
10. Srivastava M, Brito-Dellan N, Davis MP, Leach M, Lagman R. Olanzapine as an antiemetic in refractory nausea and vomiting in advanced cancer. J Pain Symptom Manage 2003; 25:578–582.
11. Soriano A, Davis MP, et al.  Malignant bowel obstruction: individualized treatment near the end of life.  CCJM 2011 Mar;78(3):197-206.

Version History:  This Fast Fact was originally edited by David E Weissman MD.   2nd Edition published August 2005; 3rd Edition May 2015; 4th Edition May 2025.
Conflicts of Interest: None to report.