Management of Small Bowel Crohn Disease




Introduction


Crohn disease is described according to age of onset, disease location, and disease behavior. The disease location usually remains constant throughout a patient’s lifetime and is categorized as disease of the terminal ileum with or without cecal disease, disease of the colon, or disease of the ileocolon. Further involvement of the intestine proximal to the terminal ileum (i.e., the upper gastrointestinal tract) can coexist with any of the other disease locations. Disease behavior generally begins as an inflammatory process but ultimately evolves into stricturing or penetrating disease in most patients. The location and behavior of the small bowel disease are important because they directly influence medical and surgical management.




Medical Management


The appropriate treatment of a patient with Crohn disease of the terminal ileum or upper gastrointestinal tract typically begins with individual or combination medical therapy in the form of antibiotics, 5-aminosalicylic acid compounds, glucocorticoids, immunomodulators, or biologic agents. Although medications are traditionally used in an escalating or “bottom-up” manner as the disease shows itself to be unresponsive to the medical regimen, recent evidence suggests that early aggressive or “top-down” treatment might be more effective. Regardless of medical treatment, surgery is ultimately required in most patients, with many patients requiring more than one intestinal operation over their lifetime.




Indications for Surgery


The indications for surgery in a patient with Crohn disease are considered under two broad categories: failed medical therapy or disease-associated complications. Failed medical therapy can manifest as persistent symptoms despite appropriate medical therapy, but it also includes failure as a result of poor compliance, intolerance of medications, debilitating adverse effects, or concern for potential risks/complications. Disease complications can be classified as acute (e.g., abscess, free perforation, and hemorrhage) or chronic (e.g., growth retardation, fistula, neoplasia, and obstruction). The most common indications for surgery in a patient with small bowel Crohn disease are failed medical therapy and obstruction.




Preoperative Considerations


Any patient requiring surgery for small bowel disease should undergo routine laboratory studies to exclude anemia and electrolyte abnormalities. Assessment of nutrition-related proteins (e.g., transferrin and prealbumin) is reserved for a patient with recent poor caloric intake or substantial weight loss (>10% well weight). Simple deficits such as hemoglobin less than 7.0 g/dL, hypokalemia, and hypomagnesemia should be corrected. Malnutrition resulting from systemic inflammatory mediators will not improve with hyperalimentation, but 7 to 10 days of parental nutrition should be considered in elective situations if the cause of malnutrition is poor caloric intake. Attempts at smoking cessation should also be strongly encouraged and supported when appropriate because of the negative impact of smoking on operative morbidity and disease recurrence. Regardless of the setting, a patient who may or will require temporary fecal diversion should be marked in at least one abdominal quadrant in an area that is easily visible and remote from bony structures and scars. The mark should be acceptable in any position (e.g., lying, sitting, and standing).


A patient scheduled for elective surgery should usually undergo endoscopic and imaging evaluation if these investigative studies have not been performed recently. Colonoscopy is indicated to exclude primary or secondary colon involvement, and an upper endoscopy is selectively performed based on the patient’s symptoms to search for primary or other disease (e.g., gastritis or peptic ulceration). Magnetic resonance and computed tomographic (CT) enterography are typically favored compared with barium contrast studies because they more accurately identify inflammation, strictures, and fistulas affecting the small bowel ( Fig. 75-1 ).




FIGURE 75-1


Computed tomographic enterography demonstrating inflammation of the terminal ileum.

(Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography copyright 1998-2016. All Rights Reserved.)




Operative Approach


Laboratory, endoscopic, and imaging studies are used to justify and to plan the operation, but additional findings at the time of the procedure are often encountered and must be addressed by the surgeon. Several tenets that aid in conduct of the operation include the following:




  • Crohn disease is incurable



  • Intestinal complications are the most common indication for surgery



  • Surgical options are influenced by myriad factors



  • Asymptomatic disease should be ignored



  • Nondiseased bowel can be involved by inflammatory adhesions or internal fistulas



  • Resection margins should be conservative



  • Division of the mesentery can be difficult



No physician or surgeon can cure Crohn disease, and its nature is to recur even after all visible disease has been eradicated. Therefore, the surgeon must focus on safely returning the patient’s quality of life to an acceptable and durable level by managing any disease linked to current symptoms or potential future symptoms. Accordingly, segments of small bowel disease that are incidentally discovered when operating for other known disease occasionally can be ignored, especially if the segment is not associated with bleeding, perforation, or upstream bowel dilatation or if the patient is at risk for existing or future short bowel syndrome.


A laparoscopic approach to small bowel Crohn disease is generally favored in the elective setting for a patient undergoing a first-time operation for uncomplicated disease because this approach is associated with improved postoperative pulmonary function, less postoperative pain, decreased operative morbidity, improved cosmesis, shorter length of stay, and reduced costs without a higher risk for disease recurrence. Experienced surgeons also often use this minimally invasive technique for patients with recurrent disease or associated fistulas for the same reasons. Conversion rates are acceptable.




Surgical Options


The surgical options that can be used in isolation or combination for small bowel Crohn disease include bypass, resection, and strictureplasty.


Bypass


Internal bypass of the diseased small bowel segment has evolved from the procedure of choice when Crohn disease was first described to an operation of limited utility because of early problems with mucoceles and later troubles with cancers associated with the bypassed bowel. Internal bypass is still used for disease of the distal stomach and duodenum when resection or strictureplasty cannot be performed. Bypass is also appropriate in disease of the terminal ileum when resection of severely inflamed bowel risks injury to the iliac vessels or other retroperitoneal structures. In this scenario, the diseased ileum can be bypassed to allow for resolution of the inflammation followed by a planned resection 6 months later. External bypass is used to avoid or protect an anastomosis in a patient with coagulopathy, debilitating comorbid conditions, high-dose glucocorticoid usage, or severe malnutrition, as well as someone requiring an operation associated with undrained sepsis, purulent or feculent peritonitis, or excessive blood loss.


Resection


Resection remains the operation of choice for a patient with disease of the terminal ileum and in many instances of more proximal small bowel disease. The extent of disease can be judged by palpation of the mesenteric margin of the bowel wall ( Fig. 75-2 ) or intraoperative enteroscopy, with the former technique preferred by most experienced surgeons. The affected bowel is resected with limited (2-cm) margins of grossly normal bowel that can be confirmed by opening the resected bowel after its delivery from the operative field. A grossly normal limited resection margin is not associated with a higher recurrence rate than that associated with a microscopically disease-free or extensive margin. An anastomosis is created in appropriate scenarios using sutures or stapling instruments in any manner of configuration (e.g., end-to-end, end-to-side, and side-to-side). The method used to construct and configure the anastomosis does not seem to significantly affect the risk for early complication or later recurrence.


Jul 15, 2019 | Posted by in GENERAL | Comments Off on Management of Small Bowel Crohn Disease
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