Case Files Surgery, (LANGE Case Files) 4th Ed.

SECTION II. Clinical Cases

CASE 26

A 52-year-old woman presented with atrial fibrillation and an acute abdomen 8 days ago. She was taken to the operating room for exploratory laparotomy after the initial evaluation suggested the perforation of a hollow viscus. During the operation she was discovered to have a superior mesentery artery (SMA) embolism. She required resection of the infarcted bowel, and a jejunal-colonic anastomosis was performed. On postoperative day 8, the patient received enteral nutritional support with a polymeric formula diet through a nasogastric feeding tube. After the initiation of tube feeding, she began to produce a large amount of liquid stools. During the initial evaluation, the results of her physical examination are unremarkable except for postoperative changes. Her stool sample was analyzed and found negative for fecal leukocytes and Clostridium difficile.

Images What is the most likely diagnosis?

Images What is the best therapy?

ANSWERS TO CASE 26: Short Bowel Syndrome

Summary: A 52-year-old patient with atrial fibrillation required right colon and extensive small bowel resection after an embolus was found in her SMA 8 days previously. She now has severe diarrhea with stool negative for fecal leukocytes or C difficile toxin.

• Diagnosis: Malabsorption and diarrhea related to short bowel syndrome.

• Best therapy: Bowel rest and parenteral nutrition until bowel adaptation occurs.

ANALYSIS

Objectives

1. Learn the different routes of enteral nutritional support.

2. Know the advantages and disadvantages of enteral and parenteral nutrition.

3. Learn how small bowel adaptations occur following massive resection and the options for short- and long-term management of short gut syndrome.

Considerations

A patient presents with postenteral feeding diarrhea after a massive small bowel resection. The SMA supplies blood to most of the small bowel and proximal colon. Because an SMA embolus typically lodges in the distal artery, it causes necrosis of the right colon, ileum, and distal jejunum. In this case, the absence of fecal leukocytes and C difficile toxin makes an infectious cause of the diarrhea unlikely. Her surgical history and negative laboratory test results indicate malabsorption related to short bowel syndrome.

The most important therapeutic objective for this patient is maintenance of nutritional status. The long-term prognosis of patients with short bowel syndrome is influenced by the length and location of the residual bowel, the absorptive function of the residual bowel, and age of the patient. This patient has lost her distal small bowel proximal colon. Theoretically, with appropriate nutritional and pharmacological support, this patient should have enough residual intestines to maintain long-term nutritional needs. A period of adaptation will be required for her to recover bowel function.

APPROACH TO: Short Bowel Syndrome and Malnutrition

DEFINITIONS

SMALL BOWEL SYNDROME (SBS): Malabsorption and maldigestion due to extensive resection of small bowel. The clinical features of SBS generally occur when less than 180 to 200 cm of functional intestine remains in an adult. Factors other than bowel lengths that contribute to SBS-related symptoms include the functionality and location of the residual intestines, the presence or absence of underlying intestinal pathology, and the presence or absence of the pylorus and ileocecal valve. Survival of patients with SBS is determined by the length and function of the residual intestines and patient age.

NECROTIZING ENTEROCOLITIS: Extensive ulceration and necrosis of the ileum and colon in premature infants in the neonatal period; possibly due to perinatal intestinal ischemia and bacterial invasion.

TOTAL PARENTERAL NUTRITION (TPN): Nutrition maintained entirely by central intravenous injection or other nongastrointestinal route.

CLINICAL APPROACH

Pathophysiology

Short bowel syndrome, which results from either extensive bowel resection or a functional defect such as radiation enteritis or severe inflammatory bowel disease, is characterized by diarrhea, dehydration, electrolyte disturbance, malabsorption, and progressive malnutrition. The ileum and jejunum of the small intestine are the most important organs in dietary nutrient digestion and absorption. Nutrients are digested in the small intestinal lumen and absorbed by intestinal epithelia lining along the lumen. The normal small bowel length is approximately 300 to 500 cm. An individual with 90 to 180 cm of small bowel (or approximately a third of the normal intestinal length) may develop transient diarrhea and malabsorption, whereas individuals with less than 60 cm of small bowel may require permanent parenteral nutrition. The most common causes of short bowel syndrome are Crohn disease and mesenteric infarction in adults and necrotizing enterocolitis and midgut volvulus in infants.

After an extensive small bowel resection, the remaining intestine undergoes both structural and functional adaptations. Structural changes include elongation, increase in villous height, mucosal surface area, bowel luminal circumference, and wall thickness. Functionally, there is usually an increase in nutrient absorption and a decrease in diarrhea and malabsorption. The adaptive process begins within 12 to 24 hours and continues for 1 to 2 years. The degree of intestinal adaptation depends on many variables, including the length and site of intestinal loss, the functional status of the remaining bowel, and the elapsed time from the insult. Intestinal failure associated with short bowel syndrome may be temporary or permanent.

Recent scientific and clinical evidence suggest that the colon is involved in nutrient absorption. The restoration of intestinal continuity in patients with short bowel syndrome may have some advantages, including the absorption of short-chain fatty acids and the reduction in infectious complication. Some potential disadvantages with the restoration of intestinal continuity include increased diarrhea (from bile acid malabsorption) and an increase in calcium oxalate kidney stone formation.

TREATMENT

The treatment of short bowel syndrome can be generally divided into three stages of treatment: acute phase (first weeks to months), early adaptation phase (between acute phase and up to 1 year postoperatively), and long-term adaptation phase (>1 year postoperatively). Treatment emphases during the acute phase are management of postoperative complications, nutritional support mainly by parenteral route, and assessment of residual bowel length and function. Emphases of management during the early adaptation phase are to increase enteral nutritional support as tolerated, glutamine supplementation, octreotide for control of gastrointestinal (GI) losses, and trophic growth factors provision if available. Management during the long-term adaptation phase includes operative treatment, such as bowel-lengthening procedures, and assessment to determine if the patient would ultimately be able to maintain his or her nutritional status independently. In some cases, if independent nutritional status is not possible, the patient may need to be referred for consideration for small bowel transplantation.

Nutritional Support

Nutritional support is the cornerstone of short bowel syndrome management; this management is used to provide the caloric requirements and promote gut adaptation, so that the patient may eventually survive on an oral diet.

Routes of nutritional support: Enteral feeding via mouth, nasogastric or nasojejunal tube, gastrostomy, or jejunostomy; TPN; or a combination of both.

Enteral nutrition: The advantages of enteral nutrition are that it is more physiologic and more economical, and it promotes intestinal mucosal hyperplasia and gut adaptation. The disadvantage is that it requires enough healthy intestines to absorb sufficient nutrients.

Total parenteral nutrition (TPN): The advantages of total parenteral nutrition are that it provides sufficient nutrition to support growth and development in children and weight gain and positive nitrogen balance in adults regardless of the length of the bowel. The disadvantages of parenteral nutrition include intestinal atrophy, intravenous line sepsis, high cost, high morbidity and mortality (liver dysfunction), and poor quality of life. The initial decision between enteral and parenteral nutrition is based on whether the patient is able to maintain a healthy nutritional status via enteral feeding alone. With patients receiving only parenteral nutrition, a period of transition is usually needed before full enteral feedings are tolerated. Specific intestinal nutrients, such as the amino acids ornithine and glutamine, triglycerides, and soluble and short-chain fatty acids, are important in promoting adaptation.

Medical Therapy

The use of medications to reduce GI motility and secretion are helpful to reduce diarrhea and improve absorption. These medications include loperamide and codeine phosphate, proton pump inhibitors (PPIs), and octreotide. Clonidine (an α2-adrenergic agonist) may also be helpful in reducing fluid secretion. For some individuals with diarrhea related to bile acid malabsorption (generally, those with ileal resections), cholestyramine can be helpful. Glutamine and recombinant human growth hormone (HGH) in combination with dietary regimen are potential pharmacological interventions that are currently under investigation. Exogenous epidermal growth factor (EGF) and EGF in combination with HGH have been investigated and found to improve small bowel adaptation. In addition, glucagon-like peptide 2 (GLP-2) has been suggested to upregulate small bowel nutrient transport and is currently under investigation for the management of patients with short bowel syndrome.

Surgical Therapy

Surgical intervention may be useful in carefully selected patients with either temporary or permanent short bowel syndrome. Small bowel transplantation holds potential future promise. One study noted that transplant recipients had a 1-year overall survival of 69%, with three-quarters of the patients surviving without TPN. Other operative procedures, used with the goal of promoting absorption and/or delaying intestinal emptying, include lengthening of the intestine, implantation of artificial intestinal valves, and the use of reversed intestinal segments or a recirculating loop.

COMPREHENSION QUESTIONS

26.1 A 2-month-old preterm infant is noted by a neonatologist to have probable short bowel syndrome. Which of the following is the most likely cause?

A. Crohn disease

B. Hirschsprung disease

C. Necrotizing enterocolitis

D. Radiation enteritis

E. Intestinal atresia

26.2 A 40-year-old man underwent massive bowel resection (from the ligament of Treitz to the midtransverse colon) secondary to SMA thrombosis. Which of the following therapies is most appropriate?

A. Oral diet

B. Feeding gastrostomy

C. Short-term TPN and progressive advance to an oral diet

D. Oral elemental diet

E. Small bowel transplant

26.3 A 50-year-old woman has undergone multiple small bowel resections for severe Crohn disease. She notices weight loss and disturbances in electrolyte levels while on an oral diet. Which of the following therapies is most appropriate?

A. Complete bowel rest and long-term TPN

B. Small bowel transplant

C. Continued limited oral diet with short-term TPN support and progress toward a total oral diet

D. Continued observation and no intervention at this time

E. Colostomy formation

26.4 Which of the following is most accurate regarding the role of the colon in nutritional absorption in patients with short bowel syndrome?

A. Short-chain fatty acid absorption occurs in the colon.

B. The colon interferes with the absorption of nutrients.

C. The colon does not play a role in the absorption of nutrients.

D. Colonic functions become modified to resume the role of small bowel.

E. The colon contributes to bacterial overgrowth and malabsorption.

26.5 Which of the following is a beneficial effect of TPN in the treatment of short bowel syndrome?

A. TPN provides nutritional support and fluid hydration when GI absorptive properties are inadequate.

B. TPN provides nutritional support and promotes GI adaption.

C. TPN is associated with lower rates of infectious complications.

D. TPN improves liver functions.

E. TPN use interferes with enteral nutrition absorption.

ANSWERS

26.1 C. Necrotizing enterocolitis is the most common cause of short bowel syndrome in an infant of this age, particularly a preterm infant. Midgut volvulus is a potential diagnosis that needs to be entertained whenever newborns and infants present with intestinal obstruction.

26.2 E. The loss of the entire absorptive surface of the bowel in this patient is incompatible with enteral nutritional tolerance because there is no ileum or jejunum left. Therefore, small bowel transplant is an appropriate consideration. Alternatively, this patient could be maintained on long-term TPN.

26.3 C. Initial TPN and a subsequent slow reintroduction of enteral feeding are appropriate for this patient to allow for adaptive changes in the intestine.

26.4 A. Until recently, the colon was considered to be of no nutritional benefit in patients with short bowel syndrome; however, it is now known that benefits of the colon include short-chain fatty acid absorption, fluid reabsorption, and delay in intestinal transit time. Disadvantages of the colon in these patients include the absorption of oxalate leading to increased risk of calcium oxalate kidney stones, and patients with their colons in continuity are prone to the development of secretory diarrhea from bile acid exposure to the colonic mucosa.

26.5 A. TPN is an important element in the early phase of nutritional support of patients with short bowel. TPN use provides a source of nutritional and fluid intake when patients are incapable of receiving adequate enteric nutrients. TPN use has a number of drawbacks, including increase in infectious complications (from hyperglycemia and central venous access) and the promotion of cholestatic changes in the liver. In addition, the exclusive use of TPN does not allow for the continued enteral stimulation that is needed for intestinal adaptation.

CLINICAL PEARLS

Images Individuals with less than 200 cm (a third) of small bowel are at risk for diarrhea and malabsorption.

Images The most common causes of short bowel syndrome in adults are Crohn disease and mesenteric infarction.

Images Selected patients with short bowel syndrome may be candidates for small bowel transplant.

REFERENCES

Bines JE. Intestinal failure: a new era in clinical management. J Gastroenterol Hepatol. 2009;24(S3): S86-S92.

Matarese L, O’Keefe SJ, Kandil HM, et al. Short bowel syndrome: guidelines for nutritional support. Nutr Clin Pract. 2005;20:493-502.

Sax HC. Management of short bowel syndrome. In: Cameron JL, Cameron AM, eds. Current Surgical Therapy. 10th ed. Philadelphia, PA: Mosby Elsevier; 2011:124-127.