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CHAPTER 67

Meconium Ileus

Felicitas Eckoldt-Wolke
Auwal M. Abubakar

Introduction
Neonatal bowel obstruction by a thick and tenacious meconium is
known as meconium ileus. Meconium abnormalities cause multiple
neonatal intestinal obstructive disorders of varying severity, ranging
from the benign meconium plug syndrome to the complicated meco-
nium ileus associated with cystic fibrosis (CF). The largest group of
patients presenting with meconium ileus are children who suffer from
CF, accounting for 75% of all caucasian patients with meconium ileus.
In the last 20 years, a specific type of meconium ileus, not
associated with CF, has been described in premature neonates with very
low birth weights. Meconium ileus, however, does occur in up to 20%
of neonates with CF and is the earliest manifestation of the disease.
Demographics
Cystic fibrosis is the most common serious inherited defect affecting
the caucasian population. It is transmitted as an autosomal recessive
condition with a 5% carrier rate and an incidence of approximately
1:2,500 live births. Hamish et al. reported the incidence of CF in live-
1
born babies in America to be lower in blacks (1:15,000). The cystic
fibrosis transmembrane conductance regulator (CFTR) is located on the
Figure 67.1: Meconium ileus in a low birth weight baby.
long arm of chromosome 7. The delta F508 mutation is the most com-
mon mutation among caucasians. There are, however, great differences
between populations. For example, delta F508 mutation is present in
70% of CF alleles in caucasians in the United States, but accounts for
2
only 43% in African Americans. In the literature, a great racial varia-
3
tion is assumed. Meconium ileus is reported to be a rare finding in
African populations. 4–7
Premature and very low birth weight (VLBW) babies can suffer
from a condition resembling meconium ileus called meconium ileus
equivalent (Figure 67.1). Babies at risk for meconium ileus equivalent
usually can survive only in intensive care units with ventilation
8
therapy. Such units are rare in Africa, and this may be the reason why
meconium ileus equivalent is not described in large studies of neonatal
paediatric surgical care in Africa.
Aetiology
The intraluminal obstruction in meconium ileus is due to abnormally
thick and tenacious meconium (Figure 67.2). It becomes inspissated in
the distal ileum, blocking the lumen. Abnormally dilatated mucous
glands in the distal ileum secrete mucus with a very high protein
content containing an abnormal mucoprotein, which is responsible
for the tenaciousness of the meconium. In VLBW babies, the problem Figure 67.2: Meconium ileus with dilated ileum and contracted, obturated
seems to be the disproportion between the tenaciousness of normal terminal ileum.
meconium and the underdevelopment of the contractility of the bowel.
In both cases, meconium is strongly attached to the wall of the distal Uncomplicated Form
ileum, creating pellets of white meconium in a narrow lumen.
The neonate may appear relatively normal for the first 12–18 hours of
Classification life. However, as the proximal bowel fills with air, abdominal disten-
The clinical presentation varies depending on the type of meconium tion, emesis (later bilious), and failure to pass meconium are noted. On
ileus. Instances of meconium ileus can be classified into uncomplicated examination, distended loops of intestine may be visible. Bowel sounds
and complicated types. are present but sluggish. Mucosal plugs may be evacuated on rectal
examination after withdrawal of the finger.