Short bowel syndrome overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sadaf Sharfaei M.D.[2]
Overview
Short bowel syndrome is a malabsorption disorder caused by the surgical removal of the small intestine, or rarely due to the complete dysfunction of a large segment of bowel. Most cases are acquired, although some children are born with a congenital short bowel. It does usually not develop unless a person has lost more than two-thirds of their small intestine.
Historical Perspective
The first successful intestinal resection was performed in 1880. In 1935, Haymond following research on many patients with bowel resection, reported that 30 to 50% loss of bowel was well tolerated. Total parenteral nutrition (TPN) was introduced during 1960s which helped patients to survive following bowel resection.
Classification
Based on the length of the remaining bowel, short bowel syndrome may be divided into three types such as end-jejunostomy, jejunocolonic anastomosis, ileocolonic anastomosis. They have different progress from mild to severe dysfunction. All of them require home parenteral nutrition except ileocolonic anastomosis which has excellent prognosis and rarely needs parenteral nutrition. Based on the etiology, short bowel syndrome may be divided into three categories such as vascular abnormalities, mucosal disease of intestine and causes without preexisting intestinal disease.
Pathophysiology
Causes
Short bowel syndrome in adults is usually caused by surgical removal of the intestine due to different diseases including Crohn's disease, mesenteric ischemia, malignancies or radiation enteritis. Less common causes include trauma, volvulus, adhesion and iatrogenic surgery on gastrointestinal system.
Differentiating short bowel syndrome from Other Diseases
Epidemiology and Demographics
The incidence and prevalence of short bowel syndrome is difficult to estimate. All the data is derived from patients receiving home parenteral nutrition. Therefore, there are different distributions around the world. The incidence of short bowel syndrome was estimated to be 1-2 cases per 100,000 individuals worldwide per year. The prevalence of short bowel syndrome is approximately 0.3-0.4 per 100,000 individuals in the USA to 0.1-4 per 100,000 individuals in Europe. It affects all age groups. There is no racial predilection to short bowel syndrome and is reported worldwide. Short bowel syndrome affects men and women equally.
Risk Factors
Common risk factor in the development of short bowel syndrome may be iatrogenic including any operation on the gastrointestinal system.
Screening
There is insufficient evidence to recommend routine screening for short bowel syndrome.
Natural History, Complications, and Prognosis
The symptoms of short bowel syndrome usually develop immediately following bowel resection. Diarrhea may cause massive fluid and electrolyte loss. Immediately after surgery, intestinal adaptation develops in three phases, including acute, adaptive and maintenance phase. During the adaptation, structural, motility and functional changes happen. Patients need hydration and nutritional support via parenteral, enteral and oral routes. Length of remaining small bowel is the most important prognostic factor. patients with more than 200 cm length of small bowel, usually does not need parenteral nutrition. Patients with shorter small bowel may not weaned off from parenteral nutrition support. Complications might happen due to malnutrition, surgery and parenteral nutrition. Malnutrition presents with vitamin, mineral and essential fatty acids deficiencies. Complications related to surgery including thrombosis, infection, hemorrhage, atelectasis and anastomosis disruption might occur. Small intestinal bacterial overgrowth due to stasis and obstruction might happen. Chronic liver disease following parenteral nutrition is a common complication in short bowel syndrome. There is no definite cure for short bowel syndrome. However, medications and nutritional therapy significantly improve the quality of life and survival of the patients. Prognosis of short bowel syndrome depends on the location and size of the bowel resection, underlying pathology, nutrition support, pharmacotherapy, and extent of intestinal adaptation. The 2 and 5-year survival rate of patients with short bowel syndrome are approximately 80% and 70%, respectively.
Diagnosis
Diagnostic Criteria
History and Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
X-ray
Ultrasound
CT scan
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
There are several ways to prevent complications of short bowel syndrome. Management strategies and regular follow-up are needed to find and treat complications accordingly. Effective measures must be done for secondary prevention of complications following total parenteral nutrition including liver disease, cholelithiasis, kidney stone, small bowel bacterial overgrowth, lactic acidosis, lactic acidosis. Hydration, consuming supplements, antibiotic therapy, and regular monitoring with blood tests, ultrasound and scans are recommended.