Meconium blockage syndrome
Meconium blockage syndrome
Description, Causes and Risk Factors:
Low intestinal obstruction in newborn infants resulting from blockage of meconium. Meconium is the material found in the intestine in a newborn. It consists of succus entericus that is made up of bile salts, bile acids, and debris that is shed from the intestinal mucosa during intrauterine life. It is normally evacuated within 6 hours after birth or sooner in utero as a result of a vagal response to perinatal stress. Normally, meconium is invisible on a radiograph. It occasionally has a mottled appearance on abdominal radiographs during the first 2 days of life.
Meconium blockage syndrome encompasses a wide spectrum of diseases including meconium ileus, transient functional ileus of sick newborn, and meconium plug syndrome in full-term neonates. Meconium blockage syndrome in prematurity is a distinct entity from the diseases described above. It occurs in premature infants who develop obstructive symptoms several days after having passed some initial meconium.
The etiology of meconium blockage syndrome in premature infants is conjectural and probably multifactorial. Prenatal and perinatal risk factors may include any condition causing perinatal intestinal hypoperfusion or factors associated with dysmotility and stasis. Premature colon and weak peristalsis have been associated with inspissated and tenacious meconium plug because of the increased water reabsorption. Hypermagnesemia has been associated with functional obstruction in premature infants as the result of intestinal smooth muscle depression and delayed peristalsis. Maternal diabetes has been associated with functional colonic obstruction. It is hypothesized that fetal hypoglycemia causes excess glycogen production, which in turn decreases bowel motility; however, this was not found in our study. Our findings of the association of meconium obstruction in prematurity with maternal hypertension and treatment with magnesium sulfate support the hypothesis of prenatal intestinal hypoperfusion and delayed peristalsis. Presumably, severe prematurity itself, in association with compromised perfusion results in a final pathway of dysmotility. Therefore, suggestion of meconium obstruction in premature infants includes those who had maternal history of hypertension and magnesium sulfate therapy suffering from abdominal distension with meconium passage and radiographic finding of lower bowel obstruction. Amodio Vinogred et al reported on 6 patients and pointed out that maternal MgSO4 therapy may be a significant risk factor for development of meconium obstruction.
Almost all babies with meconium blockage syndrome have cystic fibrosis (CF). CF makes certain fluids and mucus in the body thicker than normal. This increases the chance that meconium will get stuck in the ileum. About one in five babies with CF is born with meconium blockage syndrome. Some babies with meconium blockage syndrome have other problems with their intestines, like a hole in the intestine (perforation).
Some babies have a blockage in their colon that may look like meconium ileus (a meconium plug), and they have small left colon syndrome. This means the last part of their colon is smaller than normal. The blockage can be washed out with an enema. The colon grows to normal size after the blockage is removed. This condition is more common in babies whose mothers have diabetes or gestational diabetes (which happens during pregnancy). Some babies with a meconium blockage syndrome turn out to have Hirschsprung's disease.
Babies with meconium blockage syndrome may have these symptoms:
Green vomit (also called bilious because it contains bile, a liquid made in the liver to help digest fats).
Swollen belly (abdomen), maybe soon after birth.
No passing of the first stool (meconium).
Babies with more complex problems — such as a hole in the intestine (perforation) — may have more serious symptoms, like these:
Breathing problems because pressure from the belly keeps the lungs from filling with air.
Very swollen, painful, red (inflamed) belly.
The disease is diagnosed radiologically, and contrast enema examination is required. Plain images are nonspecific and usually show findings of a low small-bowel obstruction. Erect abdominal radiographs, albeit seldom necessary in the newborn, show a paucity of air-fluid levels, and in most cases, no gas is seen in the colon.Water-soluble contrast enemas can be curative with passage of the meconium.
If air is introduced into the rectum from below (eg, on rectal examination), rectal gas may be visualized. In this setting, meconium in the rectum can erroneously suggest a small presacral mass. However, if air entirely surrounds the meconium mass, it will outline the contour of the mass and suggests the correct diagnosis.
If peristalsis forces gas in from the small bowel into the colon and mixes with the meconium, a granular or bubbly appearance mimicking the findings of pneumatosis cystoides intestinalis and necrotizing enterocolitis (NEC) results. If a bubbly pattern is seen within the first 12 hours of life, meconium plug syndrome should be considered, but if it arises after 12-18 hours, NEC is more likely. NEC typically occurs in preterm infants.
Contrast enema examination shows a characteristic appearance of the colon, with contrast material outlining the solid column of inspissated meconium and the wall of the colon for a double-contrast effect.
After the meconium is passed, the part of the colon from which it was evacuated may appear narrowed, and a transition zone mimicking that seen in Hirschsprung disease may be noted.
In any of these cases, meconium proximal to the apparent transition zone may take the form of a solid, cylindrical mass extending to the cecum or lumps of solid meconium may be scattered throughout the colon.
In patients with intermediate findings, individual assessment is most important.
The small, contracted portion of the descending colon in these infants has led to the term neonatal small left-colon syndrome.
The important management of meconium blockage syndrome in premature infants is early diagnosis and early treatment. Delayed diagnosis and treatment may lead to perforation and postponement in attaining adequate enteral nutrition. Isotonic sodium chloride solution enemas were effective treatment. In our study, we used 5 ml/kg/dose ISCS enemas twice a day for 2 days and then, diluted Gastrografin enemas b.i.d. with a 50% success rate. We did not use NAC that may be associated with hypernatremia and dehydration; thus, should be used with caution. We agreed that the success rate might be increased with early diagnosis and early treatment.
NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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