Meconium Ileus

Meconium ileus is a condition primarily affecting newborns, characterized by the abnormal presence of thick, sticky meconium in the small intestine, often associated with cystic fibrosis. The meconium thickens, causing obstruction and blockage, leading to symptoms like abdominal distension, vomiting, and failure to pass stool. Treatment involves addressing the obstruction through methods like enemas or surgery, and managing underlying conditions such as cystic fibrosis. Early diagnosis and intervention are crucial for a better prognosis. About 20% of cystic fibrosis cases manifest with meconium ileus, but not all meconium ileus cases are associated with cystic fibrosis. The severity of cystic fibrosis is not necessarily linked to the presence of meconium ileus, and various methods can be used to relieve the obstruction.

Diagnosis

Infants with meconium ileus typically show signs of intestinal obstruction within 24 to 48 hours after birth. About 20% of patients, especially those with complicated cases, have a history of excess amniotic fluid in the mother’s uterus. While meconium ileus is rare in premature infants, many affected infants are small for their gestational age. The three common signs of intestinal obstruction in meconium ileus are:

Abdominal distention
Vomiting of bilious (green or yellow material)
Failure to pass meconium (the first newborn stool) within 48 hours.

In complicated cases, infants usually present either at birth or shortly after, experiencing severe abdominal distention that can lead to breathing difficulties as the swollen abdomen presses against the lungs. The abdominal wall may appear red and inflamed, and these infants may seem extremely ill with unstable blood pressure. In simple obstruction cases, X-rays may reveal varying-sized loops of distended intestine and a “soap bubble” appearance in certain abdominal areas, particularly the right lower region. Some disorders with similar X-ray findings include Hirschsprung’s disease, ileal atresia, and meconium plug syndrome.

Treatment

Simple Meconium Ileus

The obstruction caused by plugs in patients with meconium ileus can be addressed through a washing procedure. This involves the use of soluble contrast material, and the success rate of this method is variable, with approximately 30% of patients experiencing relief. For those with simple meconium ileus, the surgical goal is complete evacuation of obstructing plugs and meconium from the small intestine. One approach is to irrigate the intestine and colon, creating an opening in the small intestine that can be closed or left as an ileostomy. Some surgeons prefer intestinal removal with re-attachment if all plugs can be washed out. In cases where washing is not feasible or the patient’s condition is precarious, an alternative is the creation of a temporary ileostomy, such as a double-barreled ileostomy. This allows for irrigation of obstructing plugs from the downstream intestine, and in some instances, a tube can be inserted into the distal stoma for convenience.

Complicated Meconium Ileus

Complicated meconium ileus indicates a blockage or rupture in the infant’s intestine. In such cases, it is essential to remove the affected or blocked intestine, and a double-barreled procedure is generally recommended.

After the surgery, close attention must be paid to blood, fluid, and electrolyte levels. Management of pulmonary complications, such as infection, is crucial. Patients also need meticulous nutritional care due to the compromised function of the pancreas. Supplemental pancreatic enzymes and lipid-soluble vitamins become necessary. Special formulas like Pregestimil are often the preferred choice due to varying degrees of protein, fat, and carbohydrate malabsorption.

Additionally, patients with small bowel stomas may experience significant losses of zinc, magnesium, bicarbonate, and sodium. Sodium supplementation is crucial to prevent failure to thrive in these patients.

Complications

In addition to pulmonary infections, numerous patients may experience malabsorption and intestinal obstruction. Among older children who fail to adhere to enzyme supplementation, a condition resembling meconium ileus, referred to as meconium ileus equivalent, may manifest, impacting around 10% of individuals with cystic fibrosis. The clinical presentation mirrors that of simple meconium ileus observed in newborns, with relief often achieved through enemas. Subsequent to this, additional pancreatic enzyme supplementation is administered.

During the mid-1990s, the administration of high concentrations of pancreatic enzymes, averaging a dose of 19,000 U/kg/day, led to the development of colonic narrowing in many cystic fibrosis patients. This complication necessitated surgical resection, highlighting the importance of exercising caution when employing such therapeutic approaches.

References

Wikipedia Sources

5)^ James H Hutchinson Practical Paediatric Problems 4th ed. London: Lloyd-Luke 1975 p. 314 ISBN 0-85324-114-7
6)^ Ali Hekmatnia Meconium Ileus
7)^ Peter G Jones Clinical Paediatric Surgery 2nd ed. Oxford: Blackwell 1976 pp 74-5 ISBN 0-632-00089-9
8)^ Michael S Irish Surgical Aspects of Cystic Fibrosis and Meconium Ileus [1]

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