What are the normal lengths of the different parts of the bowel in an infant versus an adult, and what is Short Bowel Syndrome (SBS)?

From the Guidelines

The normal length of the bowel in adults is typically 300-600 cm, with the small intestine being the longest part, and in infants, it is about 200-300 cm, with short bowel syndrome defined as less than 200 cm of small bowel in adults or less than 100 cm in infants. The bowel length varies significantly between infants and adults, with the small intestine in adults consisting of the duodenum (about 25 cm), jejunum (about 100-200 cm), and ileum (about 150-300 cm), and the colon being approximately 150 cm long [ 1 ]. In contrast, a full-term newborn has a small intestine measuring about 200-300 cm and a colon of approximately 60-90 cm [ 1 ].

Key Points About Short Bowel Syndrome

• Short bowel syndrome occurs when there is insufficient functional small intestine to maintain adequate nutrition without supplementation [ 1 ].
• The condition typically results from extensive surgical resection, congenital defects, or intestinal diseases [ 1 ].
• Management depends on the remaining bowel length and function, with intestinal adaptation being more robust in infants than adults due to their growth potential [ 1 ].
• Treatment typically involves specialized enteral nutrition, parenteral nutrition support, medications to slow transit time, and in severe cases, intestinal transplantation [ 1 ].
• The presence of the ileocecal valve and colon significantly improves outcomes as they slow transit time and enhance fluid absorption [ 1 ].

Important Considerations

• The terms short bowel syndrome and intestinal failure have much in common and are frequently used interchangeably, but intestinal failure is defined as the reduction of gut function below the minimum necessary for the absorption of macronutrients or water and electrolytes [ 1 ].
• Predictions on the route of nutritional support needed can be made from knowledge of the remaining length of small bowel and the presence or absence of the colon [ 1 ].
• Patients with a jejunostomy have little change in their nutritional/fluid requirements with time, while patients with a colon in continuity with the small bowel have an improvement in absorption over 1–3 years [ 1 ]. The management of short bowel syndrome should prioritize maintaining nutritional status, correcting water and electrolyte balance, and improving quality of life, with parenteral nutrition, water, and electrolytes continued when oral/enteral intake is insufficient [ 1 ].

From the FDA Drug Label

The mean length of remaining small intestine was 47 (±28) cm (range: 9 to 120 cm) In the 25 patients who had remaining colon, the colon was in continuity in 22 patients.

The normal lengths of the different parts of the bowel in an infant versus an adult are not directly stated in the provided drug label. However, the label does mention that in pediatric patients with Short Bowel Syndrome (SBS), the mean length of remaining small intestine was 47 cm. Short Bowel Syndrome (SBS) is mentioned as a condition where patients are dependent on parenteral nutrition/intravenous (PN/I.V.) support. Key points about SBS include:

• Dependence on PN/I.V. support
• Intestinal resection leading to SBS, with common reasons including gastroschisis, midgut volvulus, and necrotizing enterocolitis 2

From the Research

Normal Lengths of Bowel Parts

• The normal lengths of the different parts of the bowel in infants and adults are not explicitly stated in the provided studies.
• However, it is mentioned that short bowel syndrome is defined as a reduced residual functional small intestinal length to less than 200 cm 3.
• In infants, the residual small intestinal length can vary, with some studies reporting lengths of less than 10 cm, 10-25 cm, 25-50 cm, 50-100 cm, and more than 100 cm 4.
• The length of the small intestine in infants with short bowel syndrome can be as short as 20-40 cm, which is considered a critical length for survival 5.

Short Bowel Syndrome (SBS)

• Short bowel syndrome is a malabsorptive state that occurs following extensive small intestinal resection 4, 3.
• It is a rare condition that can lead to chronic intestinal failure (CIF) and requires long-term parenteral nutrition and/or fluids and electrolytes 3, 6.
• The most common causes of short bowel syndrome in infants and children are necrotizing enterocolitis, abdominal wall defects, jejunal ileal atresia, and midgut volvulus 5.
• The presence or absence of the ileal cecal valve can affect the length of time on total parenteral nutrition (TPN), but does not impact mortality rate 5.
• Complications of short bowel syndrome include intestinal failure-associated liver disease (IFALD), chronic renal failure, metabolic bone disease, and catheter-related complications 3, 6.