Complications
Most frequently seen in patients with terminal ileal resection due to the interruption in enterohepatic circulation of bile salts. Although loss of bile salts may cause supersaturation of bile, most gallstones are of the calcium bilirubinate type.
In patients on parenteral nutrition (PN), the lack of oral intake decreases cholecystokinin (CCK)-stimulated gallbladder contraction, further increasing the risk of gallstones.
In one study, the prevalence of asymptomatic gallstones in 84 patients with SBS requiring PN was 44%.[26]
Oral food intake can help protect against gallstone formation by stimulating CCK release, which causes the gallbladder to contract. The definitive treatment is cholecystectomy.
Acalculous cholecystitis may also occur.
Liver failure occurs in approximately 15% of all patients on parenteral nutrition (PN). After 5 years on PN, almost 50% of patients will have severe liver disease. Intestinal failure-associated liver disease (IFALD) is more common and severe in children, occurring in 40% to 60% of patients receiving PN.[52] The incidence is inversely proportional to length of intestine remaining.
IFALD consists of a combination of hepatic steatosis and cholestasis, with steatosis the more prominent histologic finding in older children and adults, and cholestasis predominant in preterm infants.
The aetiology is thought to reflect nutrient malabsorption (especially choline) and lack of portal circulation involvement in nutritional clearance.[54][55] Evidence suggests that choline deficiency plays a primary role, although development of this complication is likely multifactorial and may include repeated infections; excess lipid infusion; and, in neonates, the addition of multiple surgeries and blood transfusions.[54][56]
Hepatic aminotransferases and bilirubin concentrations should be measured frequently to assess for the development of liver disease. If liver injury develops, dextrose over-feeding should be avoided and the lipid composition of parenteral nutrition should be reduced if possible to less than 1.0 g/kg/day. Investigational studies of lecithin and choline in the prevention of this complication are promising. Retrospective and uncontrolled studies of fish oil-based emulsions suggest a benefit in children, and a fish oil-based lipid emulsion may be considered in young children.[33]
If the liver disease progresses, isolated small intestinal transplantation should be considered. Combined liver-small bowel transplantation should be reserved for patients with irreversible liver disease. The latter should be avoided by early referral to a comprehensive intestinal rehabilitation and transplant center.
Calcium and vitamin D deficiencies are common, and lead to osteopenia and osteoporosis. A small study of 15 patients with SBS on parenteral nutrition showed marked osteoporosis in the majority of patients, with average Z-scores for the lumbar spine and femoral neck of -3.35 ± 3.49 and -2.23 ± 2.11, respectively.[25]
Serum calcium and vitamin D (25-OH) concentrations need to be closely monitored and yearly dual-energy x-ray absorptiometry (DXA) scans performed.
Many patients benefit from intravenous bisphosphonate therapy.
Patients with SBS on parenteral nutrition (PN) may develop biliary sludge and obstruction. In a study of 23 patients with a normal biliary tree (ultrasound documented) who were started on PN, 100% had evidence of biliary sludge formation after 6 weeks. The biliary obstruction/sludge resolved in all patients after 4 weeks of oral re-feeding.[53]
Patients with terminal ileal resection and an intact colon have the greatest risk. In one study of 38 such patients, 24% developed calcium oxalate kidney stones within 2 years.[26]
Oxalate normally precipitates with calcium in the intestinal lumen and is passed in the stool. In the presence of fat malabsorption, fat competes with oxalate for calcium binding, increasing the amount of free oxalate absorbed in the colon. Absorbed oxalate can then form stones during renal filtration.
Treatment includes a low-oxalate diet and oral calcium supplementation.[26]
All patients who have SBS and an intact colonic anastomosis are given a low-oxalate diet to prevent this complication.
This complication is fortunately very rare.[57]
Unabsorbed carbohydrates are fermented by colonic bacteria to short-chain fatty acids and lactate, lowering colonic pH and creating a favourable environment for bacteria that form D-lactate. D-lactate is absorbed in the colon, but is only minimally metabolised.
Patients can appear inebriated and often present with inappropriate behaviour, nystagmus, and metabolic acidosis.
The diagnosis is confirmed with specific testing for D-lactate (>3 mmol/L).
It is treated with bicarbonate and complete cessation of enteral carbohydrates until symptoms resolve. There are case reports of thiamine (vitamin B1) supplementation preventing symptoms in patients with recurrent D-lactic acidosis.[58]
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