The nurse reports that no stool has been passed in an infant for 36 hours. The first stool, meconium, is usually passed by 98.5% of term infants, 100% of postterm infants, and 76% of premature infants (majority are >32 weeks) in the first 24 hours of life. The majority of premature infants have delayed passage (37% in 24 hours, 32% beyond 48 hours, and 99% by 9 days in 1 study) (Table 72–1). Delayed passage of meconium was found to be in 81% of very low birthweight (VLBW) infants. Males were found to pass stool later than females. Delayed passage of meconium can be a predisposing factor for bowel perforation. The triad of failure to pass meconium, vomiting, and abdominal distention, is a sign that the infant may have intestinal obstruction.
II. IMMEDIATE QUESTIONS
What is the stooling history? This history can give a clue to the diagnosis. An infant with a complete obstruction can pass meconium because the meconium was formed in utero distal to obstruction or a mucous stool (intestinal secretions can occur distal to the obstruction).
Has the infant passed his or her first stool? Meconium is composed of materials ingested while the infant is in the uterus and consists of succus entericus (intestinal epithelial cells, lanugo, mucus, amniotic fluid, bile salts, bile acids, and debris from the intestinal mucosa). It is not sterile because it contains enteric bacteria. 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 causes.
If meconium has been passed and normal stooling has occurred, but not in the past couple of days, consider simple constipation.
If delayed passage of meconium occurs, consider prematurity, distal intestinal obstruction, or Hirschsprung disease (observed in 90% of infants).
If meconium has never been passed, consider imperforate anus or some degree of distal bowel obstruction.
If meconium has been passed and stooling has occurred and then slowed down or stopped completely, consider small bowel obstruction.
Is there abdominal distension? Abdominal distension can be a sign of intestinal obstruction and may be present right after birth or at 24 to 48 hours, when it usually peaks. It is more common in lower obstructions, and the more distal the obstruction, the more severe is the abdominal distension. Proximal obstructions will have minimal to no abdominal distension.
If the abdominal distension is present at birth, consider antenatal intestinal obstruction/perforation from volvulus, intestinal atresia, or meconium ileus/peritonitis. Abdominal distension usually appears 24 hours or later after birth in infants with more distal or functional obstructions.
Is there vomiting? Secretions proximal to the obstruction build up and result in vomiting, which can be bilious or nonbilious. Bilious emesis is more common in proximal obstructions and suggests that the obstruction is located distal to the ampulla of Vater...