Short bowel syndrome is a complication of intestinal resection that leads to severe malabsorption, dehydration and profuse diarrhea. The diagnosis can be made by clinical criteria and patient history that includes bowel surgery. Treatment principles depend on the severity of symptoms but fluid administration, parenteral nutrition and various drugs such as proton pump inhibitors and histamine-receptor blockers are imperative in initial management, while surgery may be recommended to facilitate recovery.
Gastrointestinal symptoms such as severe dehydration, diarrhea, severe fatigue and weight loss are hallmarks of SBS . Diarrhea is often exacerbated after oral intake of either liquid or solid food . Due to loss of many vitamins, minerals and macronutrients, failure to thrive and a poor general condition that ensues within days or weeks is frequently encountered and the severity of symptoms has shown to depend on the site of bowel resection. Namely, patients with end-jejunostomy develop a more severe clinical presentation, while a somewhat slower onset of symptoms is seen in patients who underwent jejunocolic anastomosis . Because of B12 and iron loss, anemia can manifest as pale skin and tachycardia, while hypotension is a frequent finding on physical examination due to extensive volume depletion.
The most important step in the diagnostic workup is a proper patient history that may reveal recent bowel surgery. When combined with severe GI symptoms, the initial diagnosis should be made based on these criteria without hesitation. Laboratory studies should evaluate serum electrolytes, including sodium, potassium, chloride, magnesium, calcium and iron. Imaging studies are of little use as macroscopic changes seen on ultrasonography and radiography may not reveal pathological findings.
Patients in whom a strong suspicion toward SBS is made, immediate administration of intravenous fluids and electrolytes should be made done, with appropriate electrolyte corrections after the arrival of laboratory results. Oral intake is strictly prohibited in early stages of care as it may provoke further volumes loss through diarrhea . To further reduce the severity of diarrhea, the use of proton pump inhibitors such as pantoprazole is recommended to suppress gastric hypersecretion that may even lead to peptic ulcer disease . Antimotility agents, such as loperamide, histamine-2 receptor blockers, cholestyramine and octreotide are also drugs that are readily used in management of diarrhea seen in SBS . GLP-2 analogs, such as teduglutide, have shown to be of significant benefit for many patients due to their numerous positive effects such as promotion of intestinal adaptation and nutrient absorption  . Total parenteral nutrition (TPN), however, is the definite therapeutic measure . TPN provides all the necessary nutrients and gives the intestines enough time to undergo adaptation undisturbed, but life-long TPN may be required for patients in whom adaption did not occur in satisfactory levels. Moreover, adverse effects such as liver failure, bacterial overgrowth and bowel dysmotility have been documented with long-term use of TPN, which is why surgery may be performed as a last resort . The goal of surgical therapy is to increase the surface area of the small intestine or improve its capacity for absorption . By prolonging intestinal transit through reversing intestinal segments or colonic transposition, narrowing of the dilated intestinal segments (tapering enteroplasty), increasing the length of the intestine and transplantation, surgery may improve long-term outcomes .
Despite the introduction of TPN and advances in critical care medicine, the overall prognosis is still poor for the majority of patients suffering from SBS. The main prognostic factor is the degree of intestinal adaptation, a process that involves progressive functional and anatomical increase in bowel capacity for nutrient absorption after surgery . Enhanced formation of crypts, villi lengthening, motor activity, mucus production and various other compensatory mechanisms occur in the first 2-3 years after surgery and the exact physiological mechanism remains unknown . The site of resection is also an important prognostic factors, as patients with illeal resection often have better outcomes, since this part of the small intestine possesses greater capacities for adaptation than jejunum . Unfortunately, this process does not develop fully in many patients and life-long TPN is necessary, which carries many risks and significantly affects the quality of life. Case fatality ratios range from 10%-50% according to various reports , indicating that SBS is a serious condition that requires prolonged and complex interdisciplinary management.
SBS stems from a reduced surface area for absorption of nutrients and water that is caused by either single massive or repeated lesser bowel resections . Conditions such as Crohn disease or enteritis due to radiation often require extensive ileal resection, while intestinal ischemia, gastric bypass surgery and other diseases that necessitate procedures such as end-jejunostomy, jejunocolic anastomosis and jejunoileal anastomosis can also cause SBS  . In the pediatric population, necrotizing enterocolitis, volvulus repair, intestinal atresia and abdominal defects are most common indications for bowel resective surgery . In general, the definition of SBS implies a malabsorptive syndrome that develops after resective surgery that leaves less than 200 cm of viable intestine .
SBS is a condition that is rarely encountered in clinical practice, but approximately 15% of patients in whom intestinal resection is performed will develop this malabsorptive syndrome . Much higher rates are observed in patients who undergo single massive resection (75% of all cases) compared to smaller repeated resection and mortality rates were shown to be higher in this group as well . Prevalence rates of SBS in the United States are estimated at 3-4 per 1 million individuals, while incidence rates range from 24.5 per 100,000 live births to more than 300 per 100,000 neonates born before 37 weeks of gestation .
All important nutrients, including water, proteins, carbohydrates, fats, vitamins and minerals are absorbed at various parts of the GI tract. Proteins and carbohydrates are absorbed in the stomach and duodenum, while the jejunum is the site of calcium, folate, iron, magnesium, phosphorus water, fat-soluble vitamins and free fatty acid absorption  . The ileum, on the other hand, is the site of intrinsic factor and vitamin B12 absorption, as well as bile acids and moderate amounts of sodium and water . Finally, the principal action of the colon is to regulate water and electrolyte content. The site of resection may significantly influence the degree and severity of symptoms, but in general, the reduced surface area of the remaining intestine after surgery is the most important factor in the pathogenesis of SBS . Because of this loss, water, electrolytes and both micro and macronutrients cannot be absorbed at a rate that is necessary for normal metabolic functions. In addition to malabsorption, deficits of glucagon-like peptides (GLP) 1 and 2, neurotensin and YY peptide are observed, which leads to accelerated gastric emptying and more rapid bowel movement . Although the colon is often intact, increased concentrations of bile salts induce cAMP activation, leading to even further water and electrolyte loss .
Prevention of SBS is somewhat difficult due to the necessity of intestinal resection in various diseases. More importantly, however, is the prevention of its complications, such as sepsis, metabolic alterations that can include numerous dietary inefficiencies and liver failure that develops in approximately 15% of patients who are on life-long TPN . Prevention of nutrient deficiencies by performing regular evaluation of electrolytes, adequate intake of balanced calories by using less than 30% of fat of the total caloric intake, while the use of ursodexycholic acid, a drug used for treatment of billiary cirrhosis, has shown benefit in some patients, are some of the strategies used in preventive purposes .
Short bowel syndrome (SBS) is a potentially severe and life-threatening malabsorptive disease that occurs after resective bowel surgery, usually leaving less than 200 cm of intestinal length . In approximately 15% of patients undergoing surgical procedures such as end jejunostomy, jejunocolic anastomosis and jejuno-ileal anastamosis, SBS may develop . Indications for surgery among adults include radiation enteritis, Crohn disease, ischemia of the bowels and the mesenterium and gastric bypass surgery, while necrotizing enterocolitis and volvulus repair are most frequent causes in the pediatric population  . Rare cases of congenital SBS have been described in literature . Epidemiology studies have determined an incidence rate of 24.5 per 100 000 live births and the most significant risk factor is shown to be premature birth (before 37 weeks of gestation) . In this group of patients, incidence rates are around 350 per 100,000 . Other studies estimated a prevalence rate of 3-4 per 1 million individuals . The pathogenesis starts with reduction of the surface area where absorption of all micro and macronutrients, as well as water, takes place . Proteins, carbohydrates, fats, vitamin B12, iron, phosphorus, zinc and magnesium are insufficiently absorbed and the severity of malabsroption depends on the extent of bowel that is removed and the site of removal  . The majority of these elements are absorbed in the proximal 1-1.5 meters of small intestine and more severe outcomes are expected in patients in whom significant small intestinal resection was performed . In addition to malabsorption, increased concentrations of bile salts in the colon stimulate cyclic adenosine monophosphate (cAMP) production and promote further water loss . As a result of these changes, symptoms such as severe diarrhea, dehydration, failure to thrive, extreme fatigue and weight loss are hallmarks of SBS . Patient history that reveals recent intestinal resection, together with typical signs and symptoms should be sufficient to make a presumptive diagnosis. Laboratory findings often reveal anemia, hypomagnesemia, hyponatremia and hypokalemia . Rapid initiation of treatment is detrimental in these patients and consists of adequate intravenous fluid and electrolyte administration, proton pump inhibitors and antimotility agents to reduce diarrhea. Total parenteral nutrition (TPN), however, is the mainstay of long-term management of patients suffering from SBS . Patient outcomes significantly depend on the process of intestinal adaptation, a spontaneous physiological process that enhances the capacity of the remaining intestines for nutrient absorption . If intestinal adaptation does not occur within a few years after surgery, life-long TPN may be necessary, which carries a great risk for numerous complications, such as cholestasis, liver failure and development of systemic infections, whereas the quality of life is also severely impaired . Glucagon-like peptide 2 (GLP-2) analogs, such as teduglutide, an other similar drugs have shown to promote intestinal adaptation and absorptive capacities and are increasingly being used in SBS patients, mainly because they may aid in reducing the need for TPN .
Short bowel syndrome (SBS) is a condition that develops in approximately 15% of patients who undergo bowel resection surgery. It is characterized by severe malabsorption due to reduced amount of viable intestine (less than 2 meters), leading to insufficient absorption of all nutrients, including vitamins, minerals, proteins, carbohydrates, fats, and water. Numerous diseases have been described as indications for bowel surgery and consequent SBS, such as Crohn disease, enteritis as a result of radiation, mesenteric and intestinal ischemia and gastric bypass surgery. In the pediatric population, severe infections of the bowels and volvulus repair are the most common causes of SBS. This condition is considered to be a rare medical condition, affecting about 3 to 4 per 1 million individuals in the United States. Because of severe malnutrition and malabsorption, symptoms such as dehydration, profuse watery diarrhea that is provoked by oral ingestion of any kind of food, severe malaise and failure to thrive are commonly encountered. Patients are often in poor general condition and report weight loss in a matter of days or weeks. To make the diagnosis, patient history that reveals recent bowel surgery and severe symptoms that involve the gastrointestinal tract should be sufficient. Treatment requires immediate intravenous administration of fluids and electrolytes together with drugs that reduce gastric acid secretion and bowel motility such as proton pump inhibitors (PPIs), loperamide, histamine-receptor blockers and octreotide. Long-term management, however, is achieved by total parenteral nutrition (TPN), a technique that bypasses the gastrointestinal system in order to replenish the body with all the necessary nutrients. More importantly, during TPN, the intestines try to heal and trigger several compensatory mechanisms in the absence of a substantial part of the bowel, such as increased mucus production and enhancement of absorption capacity. Sometimes, bowels may heal enough so that regular nutrition through food can be continued, but it many patients, life-long TPN is necessary. This method, however, carries significant long-term complications such as sepsis and liver failure, both being life-threatening. The overall prognosis of SBS is poor, as many patients require continuous treatment during their lives and frequent complications often lead to fatal outcomes. For these reasons, a multidisciplinary approach in both treatment and prevention of complications is necessary to maintain an adequate level of quality of life.