Short bowel syndrome (SBS) is a disorder of malabsorption resulting
from significant small bowel loss secondary to congenital disease
or surgical resection. The incidence of SBS is estimated at 1200
per 100,000 live births.1 SBS is the most common cause
of intestinal failure. This is defined
as a significant reduction in functional small bowel mass, leading
to inadequate digestion and absorption, with subsequent growth failure.
Other less common causes of intestinal failure include structural
enterocyte defects and severe disorders of intestinal motility.2
At birth, the estimated small bowel length is approximately 250
cm for term or near-term infants and approximately 100–120
cm for premature infants <30 weeks="" gestation.="" small="" bowel="" length="" is="" thought="" to="" double="" in="" the="" last="" trimester="" of="" pregnancy.="" different="" systems="" have="" been="" used="" to="" describe="" sbs="" including="" those="" based="" on="" etiology,="" age,="" and="" anatomical="" considerations.="" in="" the="" context="" of="" surgical="" resection,="" the="" remaining="" small="" bowel="" length="" is="" often="" used="" to="" categorize="" disease="" severity.="" in="" a="" short="" resection,="">100–150
cm of small bowel remains, compared to 40–100 cm with a
large resection and <40 cm remaining after a massive
The small bowel has considerable adaptive capacity to compensate
for intestinal loss. Intestinal adaptation is
defined as a growth process of the remaining small bowel, through
morphological and functional changes, leading to improved absorption.
This process starts shortly after bowel loss but often continues
for months to years. Depending on the segment and length of the
lost small bowel, patients with SBS are frequently dependent on
parenteral nutrition for prolonged periods of time, sometimes indefinitely.
The use of parenteral nutrition has significantly improved the life
expectancy of children with SBS. On the other hand, long-term parenteral
nutrition can be associated with a variety of complications, some
of which can have grave consequences. Patients with SBS who fail
medical therapy or develop complications may require surgical interventions,
including transplantation. Because of the relatively high mortality,
SBS is considered among the most lethal disorders in young children.3
The small bowel is a vital organ involved in digestion, absorption,
and fluid balance. The small bowel is divided into three anatomical
segments (Figure 20–1). The first is the duodenum, which extends from the pylorus
to the duodenojejunal junction, defined by the ligament of Treitz.
The proximal half of the remaining small intestine is composed of jejunum and the distal portion is ileum. Some absorption takes place
in the duodenum, including that of iron. The main function of the duodenum
is to neutralize acidic gastric contents and mix them with intestinal,
pancreatic, and hepatic digestive secretions. Absorption mostly
takes place in the jejunum and ileum. The jejunum has an abundant
surface area enhanced by folds and numerous tall villi. The luminal
surface of enterocytes, or intestinal epithelial cells, is in turn
covered with finger-like projections termed microvilli,
which are collectively referred to as the brush
border. Villi become shorter and less abundant in the ileum,
which therefore has less absorptive surface area than the jejunum.
The center of each villus is occupied by a capillary network that
absorbs nutrients which are eventually transported to the liver
by the portal venous system. The terminal ileum has a high concentration
of lymphoid tissue that assists in immune regulation. The terminal ileum
also has site-specific ...