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CHAPTER 63

Intestinal Atresia and Stenosis

Alastair J. W. Millar
John R. Gosche
Kokila Lakhoo

Introduction • Type IIIa atresia (15%) is similar to type II, but there is a mesenteric
Atresias of the jejunum and ileum are common causes of bowel defect and the bowel length may be foreshortened.
obstruction in the neonate, with a third of infants born prematurely or • Type IIIb atresia (19%) (“apple peel” or “Christmas tree” deformity)
small for their gestational age. Stenoses are much less common and sel- consists of a proximal jejunal atresia, often with malrotation with
dom present in the newborn period due to delay in diagnosis. Whereas absence of most of the mesentery and a varying length of ileum
these conditions are associated with excellent prognoses in developed surviving on perfusion from retrograde flow along a single artery
countries, delayed presentation and limitations in resources to support of supply.
patients with delayed return of intestinal function contributes to overall
1–4
lower survival rates in many African countries. Early recognition and • Type IV atresia is a multiple atresia of types I, II, and III, like a string
proper surgical management are vitally important to improving survival of sausages. Bowel length is always reduced. The terminal ileum, as
in countries with limited access to health care resources. in type III, is usually spared.
Demographics The immediate consequence of an atresia is dilatation of the bowel
for a variable distance proximal to the first occlusion encountered. This
The incidence of intestinal atresia in the United States is approximately 1
dilated bowel, even when the obstruction is relieved by resection and
in 3,000 live births, but may be more frequent in Africa, with a reported
anastomosis or stoma formation, remains dilated, having inefficient
incidence of less than 1 in 1,000 live births, with types III and IV (see
prograde peristalsis. Surgical strategies to overcome this include back
next section) comprising 35% of the total number. Two reports from resection of this bowel to a normal-calibre intestine or reduction in
1,2
Nigeria have shown that intestinal atresias are less common than
diameter by various tapering manoeuvres.
imperforate anus, but occur with similar frequency to Hirschsprung’s
disease. Published reports suggest a higher prevalence of jejunoileal
5
atresia among African American children in the United States, but no
racial predilection has been identified by authors from African countries.
Nearly all infants with intestinal atresias develop symptoms within hours
after birth. However, several publications have documented that neonates
in African countries often do not reach definitive medical care for several
2,4
days. Unlike atresias, many patients with intestinal stenoses are not
diagnosed until well beyond the neonatal period.
Aetiology/Pathophysiology
Our present understanding of the aetiology of intestinal atresias is based
upon the classic experimental work of Louw and Barnard reported in
1955. These investigators observed that ligating mesenteric vessels and
6
causing strangulated obstruction in foetal dogs resulted in atretic lesions
of the small intestine that were similar to those observed clinically in
human neonates. Thus, atresias and stenoses of the small intestine are
believed to be due to an ischaemic insult. This aetiologic mechanism
explains the frequent association of atresias with mesenteric defects
and with other conditions that may cause strangulated obstruction of
the intestinal tract (e.g., volvulus, intussusception, internal hernias, and
gastroschisis). An ischaemic aetiology may also explain why intestinal
atresia is associated with maternal smoking and vasoconstrictor drug
exposure during pregnancy.
The morphological classification into four types has both prognostic
and therapeutic implications (Figure 63.1):
• Stenoses occurs in 11%.
• Type I atresia (23%) is a transluminal septum with proximal dilated Source: Grosfeld JL, et al. Operative management of intestinal atresia and stenosis based on
bowel in continuity with collapsed distal bowel. The bowel is usually pathological findings. J Pediatr Surg 1979; 14:368.
of normal length. Figure 63.1: Classification of intestinal atresia (see text for explanation of types
I–IV).
• Type II atresia (10%) involves two blind-ending atretic ends separated
by a fibrous cord along the edge of the mesentery with mesentery intact.