A 21-day-old girl is brought to the office due to constipation. The patient urinates 5 or 6 times per day but has a bowel movement only every 2 or 3 days; her first stool occurred at approximately 50 hours of life. The mother states that breastfeeding seems to be going well except that the patient has to be awakened for almost every feed and falls asleep within minutes of initiating a feed. The mother did not receive routine prenatal care, and the girl was born at home. Temperature is 36.1 C (97 F), pulse is 110/min, and respirations are 28/min. Birth weight and length were at the 40th and 50th percentiles respectively; her weight today is 1% below her birth weight. Physical examination reveals a calm neonate with a slightly enlarged fontanelle and mild hypotonia. The abdomen is soft and nontender with no organomegaly. Bowel sounds are normal. Rectal examination shows a normal rectal tone with no anal fissures. Skin examination reveals jaundice extending from the head to the abdomen. Which of the following is the best next step in management of this patient?

Question

A 21-day-old girl is brought to the office due to constipation.  The patient urinates 5 or 6 times per day but has a bowel movement only every 2 or 3 days; her first stool occurred at approximately 50 hours of life.  The mother states that breastfeeding seems to be going well except that the patient has to be awakened for almost every feed and falls asleep within minutes of initiating a feed.  The mother did not receive routine prenatal care, and the girl was born at home.  Temperature is 36.1 C (97 F), pulse is 110/min, and respirations are 28/min.  Birth weight and length were at the 40th and 50th percentiles respectively; her weight today is 1% below her birth weight.  Physical examination reveals a calm neonate with a slightly enlarged fontanelle and mild hypotonia.  The abdomen is soft and nontender with no organomegaly.  Bowel sounds are normal.  Rectal examination shows a normal rectal tone with no anal fissures.  Skin examination reveals jaundice extending from the head to the abdomen.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d5f8_7717_bc81_e30b6027bb6d_MD0003_00 This neonate with constipation had delayed passage of meconium (first stool at >48 hr of life), a pathologic finding in any newborn. The majority of affected neonates have either Hirschsprung disease or cystic fibrosis; however, this neonate with a large fontanelle, hypotonia, and prolonged jaundice most likely has congenital hypothyroidism. Most neonates with congenital hypothyroidism are asymptomatic at birth due to transplacental transfer of maternal T4 and are identified by newborn screening. A minority are symptomatic due to decreased gastrointestinal motility leading to delayed passage of meconium. As maternal thyroxine wanes, further slowing of gut motility causes constipation, prolonged jaundice (also reflecting hypothyroidism-induced effects on conjugation), and poor feeding. Other common features include excessive sleeping/lethargy and slow/poor weight gain. Examination can show hypotonia, macroglossia (mucopolysaccharide deposition due to decreased degradation), and large fontanelles (delayed bony maturation). Diagnosis is confirmed with laboratory findings of increased TSH and decreased T4; bilirubin levels should also be obtained in neonates with suspected congenital hypothyroidism presenting with jaundice. Treatment with levothyroxine in the neonatal period is critical to preventing neurologic deficits and developmental delay. (Choices A and C) Abdominal x-ray is useful in evaluating suspected intestinal obstruction (eg, dilated loops of bowel, air-fluid levels) or Hirschsprung disease (eg, absent rectal air, dilated proximal loops); abnormal rectal suction biopsy confirms Hirschsprung disease. Constipation in neonates with these conditions is accompanied by severe abdominal distension, bilious emesis, and/or abnormal rectal tone. (Choice B) Prune juice is an excellent treatment for neonates with functional constipation, which is characterized by hard, infrequent stools with no serious organic cause and a normal physical examination. This patient with slow growth, delayed passage of meconium, and hypotonia warrants further evaluation. (Choice D) Sweat tests evaluate for cystic fibrosis, which can present with delayed meconium passage (due to meconium ileus), as well as poor weight gain and jaundice. However, a large fontanelle and hypotonia are not typical features of cystic fibrosis, making this diagnosis less likely. Educational objective: Although most neonates with congenital hypothyroidism are asymptomatic at birth, this disorder can be a rare cause of delayed (>48 hr of life) passage of meconium. Supportive findings include constipation, a large fontanelle, hypotonia, and poor feeding and growth. Diagnosis is confirmed with elevated TSH and low T4. References: Congenital hypothyroidism. (http://www.ncbi.nlm.nih.gov/pubmed/29405999)

A 21-Day-Old Girl Is Brought to the Office Due to Constipation