What Interventions Are Effective for Relieving Acute Bowel Obstruction in Cancer and Other Conditions?­

Introduction and Scope of the Problem

Malignant bowel obstruction (MBO) is common, occurring in up to 15% of patients with cancer, and is the most common indication for palliative surgical consultation. Most frequently associated with gastric, colorectal, and ovarian malignancies, MBO occurs from spread of the primary disease causing either intraluminal obstruction or external compression by peritoneal metastases, or from treatments for the primary disease (e.g., radiation enteritis, adhesions). The multi-institute EVOCAPE-1 study prospectively followed the natural history of peritoneal metastases and found overall poor survival among this group of patients, with median survival from time of diagnosis at just over 3.1 months. MBO is considered a pre-terminal event and associated with survival ranging from 26 to 273 days, with worse survival rates among those with ascites, palpable masses, and/or continued obstruction. Prognosis varies significantly based on the pathology of origin, with poor survival among patients with gastric, pancreatic, small bowel, and/or unknown primary adenocarcinomas.

The decision to pursue surgery is complicated, as surgery may relieve the burdensome symptoms associated with MBO yet frequently carries a prohibitively high risk of complications among individuals with already poor prognoses. For example, a study by Cauley examined 875 patients with disseminated cancer undergoing emergency abdominal surgery using data from the American College of Surgeons National Surgical Quality Improvement Program and found that in those undergoing surgery for obstruction ( n = 376), 18% of patients who had surgery died within 30 days, 41% experienced a postoperative complication, and 60% were discharged to an institution. This issue is made even more challenging given the lack of high-quality evidence surrounding surgery and MBO; most studies are from single centers with small cohorts and a high level of selection bias among those considered “appropriate” for surgery. Finally, few studies examine meaningful palliative outcomes such as quality of life and functional outcomes.

In an effort to improve the study of MBO and clearly define those for inclusion in clinical trials, the International Conference on MBO Clinical Protocol Committee standardized the definition of MBO to include (1) clinical evidence of a bowel obstruction by history, physical, and radiological examination; (2) bowel obstruction beyond the ligament of Treitz; (3) intraabdominal primary cancer with incurable disease; and (4) non-intraabdominal cancer with clear intraperitoneal disease. This has informed an ongoing multicenter prospective clinical trial (Southwest Oncology Group [SWOG], clinical trial S1316) that aims to examine the quality of life (as measured by number of days alive and outside the hospital, ability to eat, days of nasogastric tube, days of intravenous hydration, days of solid food, and overall survival, among other metrics) in patients undergoing surgery versus no surgery for MBO.

Until the implications of operative versus nonoperative management in those with MBO is fully understood, treatment of MBO should be individualized, with consideration of the patient’s underlying condition and goals and the likelihood of achieving a meaningful outcome. In general, the overall goals of treatment for MBO include (1) relief of burdensome symptoms (e.g., nausea, vomiting, pain); (2) resumption of oral nutritional support; and (3) transition to desired care setting.

Relevant Pathophysiology

Intestinal luminal distension proximal to the site of obstruction leads to an inflammatory response and the release of serotonin by enterochromaffin cells. Serotonin activates the enteric nervous system and its effectors (e.g., substance P, nitric oxide, acetylcholine, somatostatin, and vasoactive intestinal peptide), which stimulate hypersecretion of mucus from intestinal crypt cells. Due to the increase in surface area of the bowel, water, sodium, and other electrolyte secretions accumulate rather than reabsorb, and the intestines contract to overcome the obstruction, leading to colicky abdominal pain, nausea, and vomiting. Without intervention, a cyclical sequence of events called the distension-secretion-­distension cycle occurs, which is characterized by continued contraction of the intestines, further influx of luminal contents, and worsening distension and subsequent symptoms ( Fig. 21.1 ). Ongoing accumulation of secretions and fluid can lead to translocation of fluid into the peritoneal cavity, bowel ischemia, perforation, or sepsis.

Summary of Evidence Regarding Treatment Recommendations

Symptoms and Evaluation

Initial management of bowel obstruction, malignant or otherwise, encompasses judicious intravenous fluid resuscitation and bowel decompression with a nasogastric tube. Cross-sectional imaging of the abdomen and pelvis is critical in determining the level and degree of obstruction and can provide insight into the etiology of obstruction, whether it be peritoneal metastases, obstructing mass, or adhesive disease. Fig. 21.2 demonstrates examples of relevant imaging findings in which cross-sectional imaging can help determine care plans. Initial management should then include hospital admission, NPO (nothing by mouth) status, and serial abdominal exams to evaluate for signs and symptoms of peritonitis.