Snapshot A 2-day-old neonate is noted in the well-baby nursery to have some abdominal distention. He had one episode of bilious vomiting. He is feeding well and does not seem altered. However, his mom is concerned that he has not passed any stool yet. Abdominal radiography shows distended loops of bowel. A barium enema shows a dilated colon with a funnel-shaped transition zone. Pediatric surgery is consulted for biopsy and surgical correction. Introduction Congenital megacolon functional (vs mechanical) intestinal obstruction Pathogenesis absence of ganglion cells/enteric nervous plexus in intestine lack of nerves causes constant contraction failure of neural crest cell migration 99% localized in rectum Genetics associated with mutations in RET gene Associated conditions risk ↑ with Down syndrome risk ↑ with Chagas disease acquired disease as a result of amastigote destruction of ganglion cells Presentation Symptoms bilious vomiting failure to pass meconium in first 48 hours of life chronic constipation large bowel obstruction Physical exam abdominal distention extremely tight anal sphincter no stool in rectal vault Evaluation Gold standard diagnosis rectal suction biopsy lack of ganglionic cells in submucosa Imaging abdominal radiography distended bowel loops lack of air in rectum Differential Diagnosis Imperforate anus Functional constipation Intussusception Duodenal atresia Meconium ileus Treatment Supportive care Surgical resection Prognosis, Prevention, and Complications Prognosis very good overall mortality < 1% normal quality of life in most patients Complications ↑ risk of enterocolitis rupture
QUESTIONS 1 of 3 1 2 3 Previous Next (M1.GI.14.62) You are examining a 2-day-old male infant with abdominal distension and bilious vomiting. His mother informs you that he has not yet had a bowel movement. On exam, you note a release of stool with digital disimpaction. An abdominal radiograph is shown in Figure A. What is the most likely cause of his condition? QID: 106448 FIGURES: A Type & Select Correct Answer 1 Maternal diabetes mellitus 1% (3/234) 2 Mutation of the CFTR gene 4% (9/234) 3 Failure of canalization of the duodenal lumen 14% (32/234) 4 Hypertrophy of the muscularis externa of the pyloric sphincter 4% (10/234) 5 Failure of neural crest cell migration 76% (178/234) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (M1.GI.12.8) A 5-day-old male is brought to your office by his mother. The infant is experiencing bilious vomiting, abdominal distension, and overall failure to thrive. A contrast enema shows a transition point at the transverse colon between dilated ascending colon and non-distended distal portion of the colon. Which of the following is the most likely etiology of this patient's disease? QID: 101902 Type & Select Correct Answer 1 Muscle hypertrophy 3% (3/90) 2 Mechanical bowel obstruction 11% (10/90) 3 CFTR gene mutation 3% (3/90) 4 Meiotic nondisjunction 2% (2/90) 5 Failure of neural crest cell migration 79% (71/90) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic (M1.GI.12.103) Two days following the home birth of her son, a mother brings the infant to the pediatric emergency room because of bilious vomiting. He is unable to pass meconium and his abdomen is distended. Endoscopic biopsy of the proximal colon demonstrates an absence of Meissner’s and Auerbach’s plexi in the bowel wall. Which of the following is the most likely diagnosis? QID: 101160 Type & Select Correct Answer 1 Hirschsprung’s disease 95% (163/171) 2 Ileocecal intussusception 1% (1/171) 3 Meckel’s diverticulum 1% (2/171) 4 Juvenile polyposis syndrome 1% (1/171) 5 Volvulus of the sigmoid colon 0% (0/171) M 2 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic