**2.3 Clinical features**

*Pediatric Surgery, Flowcharts and Clinical Algorithms*

meconium aspiration syndrome.

**2.1 Etiology**

intestinal mucosa.

microcolon.

**2.2 Pathophysiology**

present with complicated meconium ileus [14].

**2. Detailed overview of meconium ileus**

intestine, and pancreatic enzyme insufficiency.

features, investigations, and treatment will now be undertaken.

exocrine pancreatic insufficiency, and elevated sweat chloride levels.

Meconium is the first series of stools that a newborn pass. It is formed during intrauterine life and consists of shed intestinal epithelial cells, bile, succus entericus, mucus, lanugo, and amniotic fluid ingested in utero. It is a dark olive green viscous and almost odorless substance that comprises the initial stools of the newborn. Meconium contains lactic acid-producing bacteria (e.g., *Lactobacillus*) and the so-called enteric bacteria family (e.g., *Escherichia coli*) [6]. It is usually evacuated within the first 24–48 hours after birth following which the usual yellowish feces are passed by the neonate. However, there might be in utero evacuation of meconium as a result of a vagal response due to perinatal stress to the fetus. Such newborn immediately after delivery may develop signs of respiratory distress from

Meconium ileus may be associated with complications such as meconium peritonitis, ileal atresia or stenosis, ileal perforation, and volvulus with or without pseudocyst formation [7–13]. The infants with cystic fibrosis are more likely to

An overview of meconium ileus in terms of etiology, pathophysiology, clinical

Up to 20% of babies with cystic fibrosis are born with meconium ileus, and almost all babies with meconium ileus have cystic fibrosis [15, 16]. Cystic fibrosis is caused by gene mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) encoding gene [17–19]. The loss of CFTR-mediated Cl– and/or HCO3– transport by the intestinal epithelium and/or from pancreatic dysfunction is postulated as the pathogenesis of meconium ileus [20–24]. Cystic fibrosis is characterized by the triad of chronic obstruction and infection of the respiratory tract,

The pathogenesis of meconium ileus is due to hyperviscous mucus secreted by abnormal intestinal glands, abnormal concentrating processes in the proximal small

The histology is characterized by the presence of distended goblet cells in the

The simple form of meconium ileus is characterized by thickened sticky meconium obstructing the ileum with consequent proximal dilatation, bowel wall thickening, and congestion. Immediately beyond the level of the obstructing inspissated meconium in the terminal ileum, there may be a few separate gray-white globular meconium pellets. Further distally, the colon is narrow and empty—the

The complicated form may result in volvulus, atresia, necrosis, perforation, meconium peritonitis, and pseudocyst formation. These complications may manifest as incidental findings on abdominal radiographs or with clinical features suggestive of bowel obstruction caused by reactive fibro-adhesive bands due to the meconium in the peritoneal cavity or as clinical features of peritonitis. If a neonate at birth manifests features of peritonitis, it is likely due to meconium peritonitis

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At birth, the neonate may be apparently normal. However, with progression of time and feeding, the infant develops abdominal distention, bilious vomiting, and failure to pass meconium. Sometimes thickened distended bowel loops are observed through the abdominal wall filled with rubbery meconium which when palpated feel characteristically doughy [3]. Bowel sounds tend to be hypoactive, and digital rectal examination may be followed by passage of pale mucosal plugs. Meconium pellets might be palpated in the scrotum of some infants who had in utero bowel perforation. In cases complicated by peritonitis or when postnatal perforation has occurred, the infant presents with respiratory distress, marked abdominal distention with abdominal erythema, significant abdominal tenderness, and ascites.
