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The nurse reports that no stool has been passed in a premature infant that is 36 hours old. Ninety-nine percent of term infants, 100% of post-term infants, and 76% of premature infants (majority are >32 weeks) pass a stool in the first 24 hours of life. The majority of preterm infants have delayed passage (37% in 24 hours, 32% beyond 48 hours, and 99% by 9 days in one study). The time when the first meconium stool passes has been used as a marker for normal gastrointestinal functioning, and a delay can occur because of gestational immaturity, a severe illness, a bowel obstruction, or other cause. Delayed meconium passage can be a predisposing factor for bowel perforation. Males pass stool later than females, and type of feeding does not predict the time to the first stool.
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II. IMMEDIATE QUESTIONS
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Has a stool been passed since birth? If a stool has been passed since birth but not in the last 48 hours, constipation may be the cause. In small bowel obstruction, meconium can be passed and then a decrease or no stools occur. If a stool has never been passed, imperforate anus or some degree of lower intestinal obstruction may be present. Table 67–1 shows the time after birth at which the first stool is typically passed.
What is the gestational age and birthweight of the infant? An inverse relationship between gestational age, birthweight, and meconium passage exists. Premature and very low birthweight (VLBW) infants commonly have a delayed passage of stool because of immaturity of interstitial cells of the colon, increased viscosity of meconium (preemies have lack of water in stool), and lack of triggering effect of enteral feeds on gut hormones when the patient is maintained NPO. Studies show the older the gestational age, the shorter time to the first stool. Delayed meconium passage can be as high as 80% in VLBW infants. Remember that failure of a full-term or post-term infant to pass meconium within 24 hours may signify an intestinal obstruction. In preterm infants it may not.
Were maternal drugs used that could cause a paralytic ileus with delayed passage of stool? Magnesium sulfate, which is used to slow the premature onset of labor, may cause paralytic ileus. Narcotics for pain control or use of heroin by the mother may also cause delayed passage of stool in the neonate. Antenatal betamethasone exposure leads to earlier stool passage, and antenatal exposure to magnesium sulfate has conflicting results—some studies show it does not affect the timing of the first stool in premature infants and others state it was associated with delayed stool passage.
Are there any other congenital abnormalities and associated syndromes? Hirschsprung disease is associated with trisomy 21, neurofibromatosis, Waardenburg syndrome, multiple endocrine neoplasia (MEN) type 2, central hypoventilation syndrome, and cardiac septal defects.
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