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Review Article Page 1 of 6 Management of malignant bowel obstruction Robert A. Milch1, Jaclyn Schneider2 1 Clinical Surgery, State University at Buffalo School of Medicine, Palliative Care Service, 9A, Veterans Administration Hospital, Buffalo, New York 14221, USA; 2Palliative Care and Hospice, State University at Buffalo School of Medicine, Palliative Care Service, 9A, Veterans Administration Hospital, Buffalo, New York 14221, USA Correspondence to: Robert A. Milch, MD, FACS. Professor, Clinical Surgery, State University at Buffalo School of Medicine, Palliative Care Service, 9A, Veterans Administration Hospital, 3495 Bailey Avenue, Buffalo, New York 14221, USA. Email: [email protected]; Jaclyn Schneider, MD. Fellow, Palliative Care and Hospice, State University at Buffalo School of Medicine, Palliative Care Service, 9A, Veterans Administration Hospital, 3495 Bailey Avenue, Buffalo, New York 14221, USA. Email: [email protected]. Abstract: Malignant bowel obstruction (MBO) is a frequent and troubling complication in patients with cancer. The frequency of MBO has been found to be approximately 5–51% in patients with gynecological malignancies, and between 10% and 28% in primary intestinal cancers. The management of MBO challenges clinicians, patients and their families. The management of MBO includes operative surgical interventions and non-operative medical. Keywords: Malignant bowel obstruction (MBO); management; pain; palliative Care Received: 09 May 2016; Accepted: 05 August 2016; Published: 18 August 2016. doi: 10.21037/xym.2016.08.07 View this article at: http://dx.doi.org/10.21037/xym.2016.08.07 Introduction Malignant bowel obstruction (MBO) is a frequent and troubling complication in patients with cancer, especially those of digestive or gynecological origin, whether as a primary presenting symptom or associated with advanced or metastatic disease. MBO can be divided into mechanical or functional etiologies, both of which result in the inability for flatus and contents to flow through the gastrointestinal tract. The obstruction may be at one or many sites along the bowel from the esophagus to the ano-rectum, and may partially or fully obstruct the bowel lumen. Even though the patient population that develops MBO generally has advanced cancer, the obstruction per se may be benign or malignant (1). Prevalence Bowel obstruction involves the small intestine roughly twice as frequently as it does the colon (2). The frequency of MBO has been found to be approximately 5–51% in patients with gynecological malignancies, and between 10% and 28% in primary intestinal cancers (3). It is also © Xiangya Medicine. All rights reserved. reported in patients with lymphoma, melanoma, lung, and pancreaticobiliary neoplasms. MBO is the root cause of death in patients with ovarian cancer, most of those patients dying within a year of developing the obstruction (4). Patients with MBO due to metastatic disease face a poor prognosis due to risks of aspiration, pneumonia, and malnutrition, leading to an estimated life expectancy after MBO of 1–9 months (5,6). Because its occurrence is of such prognostic significance, discussions regarding the realistic goals and the plan of care, individualizing for each patient and their unique circumstances, need to be had (7). Pathophysiology Gastric emptying and flow through the bowel is impeded either mechanically or functionally in a MBO. Several mechanisms have been described, though the end result is the same. Patients with previous abdominal or pelvic surgeries for malignancy are predisposed to mechanical obstructions due to the development of adhesions, both “benign” (i.e., fibrotic) and of malignant origin. Tumors themselves can cause intraluminal or intramural occlusion and directly block bowel transit. Primary tumors xym.amegroups.com Xiangya Med 2016;1:23 Page 2 of 6 or recurrence of omental and mesenteric masses can extrinsically cause occlusion by kinking the bowel. Radiation fibrosis and intraperitoneal chemotherapy can also cause extrinsic occlusion (8). Functional obstruction should be thought of as a disorder of motility. Infiltration of the myenteric or celiac plexuses can disrupt nervous system signaling resulting in decreased or disordered peristalsis and obstruction. Tumors may also infiltrate the intestinal muscularis, rendering it unable to contract and relax properly. A subset of patients with Autoimmune Paraneoplastic Autonomic Neuropathy, which is a paraneoplastic syndrome, may develop autonomic disturbances which can cause pseudo-obstruction (9). Once the bowel transit is disrupted, regardless of the mechanism, there is an accumulation of luminal contents and an accumulation of secretions which are not absorbed. This leads to an increased secretion of water and sodium into the lumen and a decrease of water and sodium reabsorption from the bowel. The secretions collect in the lumen, increasing bowel and abdominal distension, damaging the intestinal epithelium, releasing cytokines and other noxious compounds, and resulting in a widespread inflammatory response. The intraluminal pressure rises and may obstruct venous drainage in the area affected, which may eventually lead to intestinal mucosal slough or even perforation, though more extensive, frank gangrene is uncommon in the absence of a “closed loop” obstruction (1). Clinical presentation The patient’s history and the clinical presentation of MBO can often lead the clinician to the location of the bowel obstruction. Though colorectal cancer patients usually present, at least initially, with single-site large bowel obstructions, gynecologic cancer patients or others with peritoneal carcinomatosis often suffer from multiple jejunal and ileal occlusions, and thus with different symptomatology (10). The obstruction that results as a consequence from narrowing of the bowel lumen is often chronic, developing over weeks and months, and incomplete, which may lead to vague symptoms until the lumen becomes near- or completely obstructed (11). Common symptoms of MBO include nausea, vomiting, colicky abdominal pain vs. continuous pain, xerostomia, constipation, and overflow diarrhea (12). Functionally, the bowel attempts to overcome the evolving obstruction by increasing frequency and intensity of contractions, which results in colicky abdominal © Xiangya Medicine. All rights reserved. Xiangya Medicine, 2016 pain. As described previously, due to the obstruction the bowel becomes edematous and luminal contents increase due to excess secretions, leading to nausea and vomiting. With the inflammatory response then comes abdominal distension. Overflow diarrhea may result as the resistance to flow of fecal material increases, gut flora acts to liquefy contents, and these are finally forcefully expelled (12). Obstruction in the proximal gastrointestinal tract usually results in emesis of recently ingested material. The presence or absence of bile in the emesis indicates a level of obstruction above or below the pylorus and proximal small bowel. In small bowel obstructions, vomiting is usually watery or bilious and occurs within 45 minutes to 1 hour of ingestion, whereas it takes several hours or a time later in the day for a patient with distal small intestinal or large bowel obstruction to report worsening nausea and vomiting (13,14). If patients report intense crampy pain in brief intervals, it is often as indication of a jejunoileal obstruction or “high” SBO (14). Pain, cramps or emesis occurring later in the day, often described with fecaloid content, indicates a more distal location of the obstruction. The pain related to a small bowel obstruction is generally periumbilical and colickly, as compared to the steadier, localized pain in a large bowel obstruction which may or may not be episodic or colicky. This acute phase pain often presents as an exacerbation of more chronic pain from extensive intra-abdominal disease; each requires directed therapy, which will be described. When the abdomen becomes distended, which occurs more frequently in distal small or large bowel obstructions, continuous pain with variable intensity is often reported (13). Constipation or obstipation may also occur intermittently with a partial obstruction, whereas the patient may report scant flatus or bowel movements initially with a complete obstruction, followed by complete obstipation (15). Diagnosis “Listen to the patient, doctor. He is trying to help you.” —William Osler, Aphorisms The key to patient care is in obtaining a thorough history and physical. Though the diagnosis of an MBO is often made clinically, it is usually confirmed through the use of radiographic modalities. Furthermore, given the emphasis on cost effective medicine, it seems prudent to discuss which test(s) should be ordered within the first 24 hours of presentation to investigate a MBO. In addition xym.amegroups.com Xiangya Med 2016;1:23 Xiangya Medicine, 2016 to radiographic evaluation, blood work should also be obtained, as these patients frequently have both acute and chronic metabolic abnormalities. A plain radiographic abdominal series (upright, flat, decubitus views) of the abdomen is the easiest and least expensive way to define the extent and estimated location of the obstruction. However, plan X-rays have their limitations; an ileus often looks similar to an obstruction, and multiple sites may be involved, which is difficult to discern on a plain film, and the physician may be limited by the lack of sensitivity when trying to diagnosis a MBO, as studies have shown that as many as 75% of plain X-rays may be nondiagnostic (16). Regardless of its limitations, the first step in diagnosing a bowel obstruction radiographically should be an abdominal X-ray in which the presence of dilated bowel loops and air-fluid levels may suggest an MBO. Contrast radiography may distinguish between mechanical and functional causes as well as localize the site and extent of the obstruction (17). The use of this study can be limited if the patient is suffering from intractable nausea, is unable to swallow the contrast, or contrast cannot be placed via an enteric tube. Water-soluble contrast, such as gastrografin, is preferable to barium as barium may be retained or cause subsequent impaction or aspiration (12). Computed tomography (CT) scans have become the imaging tool used most frequently when a patient has a suspected MBO, as it has a specificity of 100% and a sensitivity of 94% (16). Abdominal/pelvic CT scans with both oral and intravenous contrast agents can localize an obstruction, reveal lymphadenopathy and bowel wall irregularities, as well as delineate the extent of tumor burden in the abdomen and pelvis (18). Because of their specificity and sensitivity, other forms of radiography are generally not used as CT scans with contrast are the most valuable (19). Though MRI may provide more detailed information regarding the extent of disease (e.g., peritoneal implants), it is more cumbersome, restrictive, and expensive, hence less frequently employed in clinical practice in favor of the CT scan. Operative surgical management “First, he would have to know when or not to operate, then how to operate, then when to stop operating.” —Dr. Charles Mayo, on the qualities in the surgeon chosen to operate on him Consideration of operative intervention for MBO requires © Xiangya Medicine. All rights reserved. Page 3 of 6 deliberation and judgment, with individualization of its application to the case at hand. The penalties to be paid for imprudent intervention, with the attendant rates of complication, death, and failure to provide meaningful symptom palliation, let alone life prolongation, are too significant to be minimized. Discussion and concurrence regarding the goals of care, realistic expectations for outcomes both operative and beyond, framed substantively and compassionately beyond the common rosary of “potential risks and benefits” need be had with the patient, if possible, and with surrogate decision-makers. For the patient with unproven intra-abdominal malignancy and fair-good performance and nutritional status, it is generally agreed that laparotomy is indicated to establish a definitive diagnosis, stage the disease intraabdominally, and relieve the obstruction by venting, lysis, resection, bypass, or debulking. Operative surgical intervention in other circumstances needs be nuanced by known outcomes in patient populations balanced against what constitutes “benefits” for the individual patient consistent with their overall goals for care. Reasonable candidates for exploration are those with an estimated life expectancy of 2 or more months, an ECOG performance status of two or better, a Palliative Performance Scale (PPS) rating of 40 or more, and slowly growing tumors. Ominous prognostic factors for surgical intervention include those patients with palpable abdominal masses, extensive ascites, multiple levels of obstruction, distant metastases, a history of abdominal radiation, hepatic or renal insufficiency, malnutrition/hypoproteinemia <2.5 gm albumin, or previous laparotomy for obstruction. Multiple series of patients with these co-morbidities reveal morbidity/complication rates 7–90%, subsequent reobstruction in 10–50%, and mortality rates 15–30% with a disconcerting number occurring in less than 30 days (20,21). For certain lesions, endoscopic stenting may offer an alternative to formal surgical intervention, offering either temporizing palliation of obstruction or a “bridge” to subsequent formal laparotomy. This approach may be considered for patients with lesions of the esophagus, gastric outlet and duodenum, or distal colon/proximal rectum who have a single point of obstruction or extensive regional disease, or who are otherwise too high a risk for more extensive surgery. For proximal lesions, stenting offers relief of nausea and vomiting and shorter hospitalizations and fewer complications than “open” surgical approaches, as well as avoidance of intestinal stomas. In experienced hands, even some distal duodenal and proximal colonic xym.amegroups.com Xiangya Med 2016;1:23 Page 4 of 6 lesions are amenable to stenting. Initial success rates, both technical and clinical, are reported >85%, with immediate (perforation, bleeding) complication rates <10%, and subsequent stent migration or occlusion 10–15% (22). Non-operative management General considerations For many patients with MBO, placement of a nasogastric tube is a prudent initial or temporizing intervention allowing for decompression of the often painful, distended proximal gastrointestinal track as fluid and electrolyte abnormalities are corrected and subsequent care deliberations made. However, long term use of NG tubes is uncomfortable and not without its own complications such as sinusitis, aspiration, xerostomia, and even social isolation. Fortunately, clinical experience has demonstrated that the majority of patients with MBO can be satisfactorily managed as described below without prolonged nasogastric intubation. For those patients not considered operative surgical candidates or those whose symptoms do not respond to medical therapy, a venting gastrostomy should be considered as it may provide significant relief of nausea, vomiting and distension. Similarly, intravenous hydration is usually an appropriate initial step in restoring depleted intravascular volume, correcting electrolyte abnormalities, and clearing accumulated metabolites. However, prolonged use of crystalloid fluids, particularly in malnourished or hypoproteinemic patients, leads to increased extravascular fluid, uncomfortable edema, increased lung water with pulmonary complications, and does not prevent the sensation of thirst. Much of the perception of thirst derives from dry oral mucosa, and all patients with restricted PO intake should have meticulous attention to mouth care and oral hygiene, including scheduled routine moisture every 2 hours and artificial saliva applied to tongue, lips, and palate every 4–6 hours. Like surgical intervention, the use of total parenteral nutrition (TPN) needs be a studied decision. The majority of patients with MBO or extensive cancers, particularly those with cancer cachexia, do not benefit from TPN, as manifested by lack of significant improvement in qualityof-life measures, performance status, or overall survival (7). Moreover, as a technical intervention requiring close monitoring and frequent manipulations, it can be a distraction or impediment to social interactions. In © Xiangya Medicine. All rights reserved. Xiangya Medicine, 2016 addition, it is not without its own risks and complications such as local infection, line sepsis, vascular thrombosis, and hyperglycemia. While it may benefit in select patients who are likely to die of starvation rather than the malignancy, or in time-limited goal-specific circumstances such as family milestones, its utilization should be accompanied by clearly articulated goals and agreed upon parameters for assessing its benefits and continuation (2). Medical management Medical management seeks minimization of pain, nausea and vomiting. As orally administered drugs are inconsistently absorbed in the presence of nausea, distension, and stasis, and certainly with emesis, medications should be provided initially by parenteral routes, either intravenous, subcutaneous, or (rarely) intramuscular. Once nausea and emesis are controlled and gastrointestinal motility restored—a not uncommon outcome often lasting many weeks—consideration can then be given to sublingual, oral or transdermal administration of some of the pharmacologic. However, it is almost always necessary to use a combination of analgesics, antiemetics, anticholinergics, corticosteroids, and octreotide to achieve symptom resolution. Once achieved, many of the drugs used—such as morphine, metoclopramide, haloperidol, and glycopyrrolate—are compatible in solution and can be combined for a consolidated infusion. Pain Two types of pain are typical in patients with MBO. The first is the “background” pain of extensive malignancy, usually constant or continuous. This is dealt with by titration to effect of potent opioids such as morphine, hydromorphone, fentanyl, or methadone. Co-analgesics such as ketorolac may have an opioid-sparing result, particularly if used short-term as other components of the regimen take effect. Colicky pain results from the increased or discoordinated effort of peristalsis, particularly as distension progresses. Paroxysms occur at more frequent intervals with jejunal obstructions than with more distal or ileal obstructions. These are treated with anticholinergics, which inhibit motility while also decreasing intestinal secretions and emesis. Glycopyrrolate in doses of 0.1–0.2 mg SQ/IV/1–2 mg PO every 6–8 hours may be the drug of choice given its pharmaceutical versatility. Moreover, it has fewer cardiac side effects and a lower likelihood of triggering xym.amegroups.com Xiangya Med 2016;1:23 Xiangya Medicine, 2016 delirium than atropine (0.4 mg IV/SQ every 6–8 hours) or scopolamine (0.4 mg IV/SQ every 6–8 hours; transdermal 1.5 mg every 3 days (2). Nausea/vomiting A variety of drugs are useful for treating nausea and vomiting. Haloperidol, a selective D2 antagonist, can be used SQ/IV or subsequently PO in doses from 0.5–2 mg every 4–6 hours, with the added advantage of treating the delirium which often accompanies advanced illness. Phenothiazines such as prochlorperazine and chlorpromazine are also effective, though they cannot be administered subcutaneously. Metoclopramide is versatile, both a D2 antagonist and a 5HT4 agonist, thus combining the central chemoreceptor trigger inhibition of the phenothiazines with a pro-motility action (23). Effective in doses of 5–10 mg SQ/IV every 6 hours, it is helpful in incomplete obstructions and as other components of therapy takes effect. It should be dose adjusted or discontinued if colic worsens, and is contraindicated in fixed, complete obstructions. Olanzapine inhibits multiple neurotransmitters involved in initiating emesis, and is seeing increasing use in problematic cases of intractable nausea. An atypical antipsychotic, it is used in doses of 2.5–10 mg/day for bowel obstruction, is available as a sublingually dissolving tablet and, in restricted use, as an intramuscular injection (24). Page 5 of 6 Dosed as 100–200 micrograms SQ or IV q 6–8 h, it is considered an essential component in non-operative management of nausea, vomiting and colic (26). Summary “Same disease, different patient.” —Old surgical adage The management of MBO challenges clinicians, patients and their families. Operative surgical interventions must be judiciously employed given significant associated morbidity and mortality, and less invasive procedures such as stenting or venting may provide substantive benefit. Non-operative medical management is often successful in relieving its distressing symptoms, often for many weeks or several months, but because MBO, particularly if inoperable, is a harbinger of limited life expectancy, its occurrence calls for comprehensive, compassionate discussions with patients and families, and coordinated care tailored to each patient and their caregivers, to identify and achieve mutually agreed upon, realistic goals of care. Acknowledgements None. Footnote Corticosteroids The presumed mechanism by which corticosteroids help ameliorate MBO is by inhibiting the inflammatory response and reducing peri-tumoral edema and associated pain. They likely also act centrally to reduce nausea. Their net effect is improvement of bowel function, often relieving incomplete obstruction temporarily and helping restore bowel function. Dexamethasone in doses 8–16 mg/day IV/SQ is most frequently chosen, usually for a trial period of 5–7 days to assess for efficacy and continued indefinitely if effective (25). Antisecretories An additive to the effect of anticholinergics in reducing intestinal motility, octreotide inhibits release of many intestinal secretions, including gastrin, vasoactive intestinal polypeptide, pancreatic enzymes, and bile. It also reduces splanchnic blood flow, thereby reducing the vascular congestion of the bowel wall which accompanies MBO. © Xiangya Medicine. All rights reserved. Conflicts of Interest: This article has been originally published in the book The Art and Science of Palliative Medicine. References 1. Krouse RS, McCahill L, Easson A, et al. When the sun can set on an unoperated bowel obstruction: management of malignant bowel obstruction. 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Surgical management of malignant bowel obstruction: strategies towards palliation of patients with advanced cancer. Curr Oncol Rep 2009;11:287-92. 21. Feuer DJ, Broadley KE, Shepherd JH, et al. Surgery for the resolution of symptoms in malignant bowel obstruction in advanced gynecological and gastrointestinal cancer. Cochrane Database Syst Rev 2000;(4):CD002764. 22. Turner J, Cummin T, Bennett A, et al. Stents and stentability: treatment for malignant bowel obstruction. Br J Hosp Med (Lond) 2008;69:676-80. 23. Ripamonti CI, Easson A, Gerdes H. Management of Malignant Bowel Obstruction. Eur J Cancer 2008;44:1105-15. 24. Glare P, Pereira G, Kristjanson L, et al. Systematic review of the efficacy of antiemetics in the treatment of nausea in patients with far-advanced cancer. Support Care Cancer 2004;12:432-40. 25. Feuer DJ, Broadley KE. Corticosteroids for the resolution of malignant bowel obstruction in advanced gynecological and gastrointestinal cancer. Cochrane Database Syst Rev 2000;(2):CD001219. 26. Mercadante S, Casuccio A, Mangione S. Medical treatment for inoperable malignant bowel obstruction: a qualitative systematic review. J Pain Symptom Manage 2007;33:217-23. doi: 10.21037/xym.2016.08.07 Cite this article as: Milch RA, Schneider J. Management of malignant bowel obstruction. Xiangya Med 2016;1:23. © Xiangya Medicine. All rights reserved. xym.amegroups.com Xiangya Med 2016;1:23