A 3-week-old boy with discharge from the umbilicus is brought to the clinic by his parents. His postnatal course was uncomplicated, with shriveling of the cord around 14 days of life. Vital signs are normal. Examination of the area reveals a small reducible umbilical hernia, minimal clear to straw-colored discharge from the umbilicus, and erythema around the area. Laboratory results are as follows: Which of the following is the most likely cause of this child's condition?

Question

A 3-week-old boy with discharge from the umbilicus is brought to the clinic by his parents.  His postnatal course was uncomplicated, with shriveling of the cord around 14 days of life.  Vital signs are normal.  Examination of the area reveals a small reducible umbilical hernia, minimal clear to straw-colored discharge from the umbilicus, and erythema around the area.  Laboratory results are as follows:  Which of the following is the most likely cause of this child's condition?

Quizplus · Accepted Answer

11ec160b_3751_0333_9249_8b00f7e807c0_MD0001_00 Around 3 weeks gestation, the yolk sac forms a protrusion (allantois) that extends into the urogenital sinus. The upper part of the urogenital sinus gives rise to the bladder. The allantois, which originally connected the urogenital sinus with the yolk sac, becomes the urachus, a duct between the bladder and the yolk sac. Failure of the urachus to obliterate before birth leads to several abnormalities: Complete failure of obliteration of the urachus results in a patent urachus that connects the umbilicus and bladder. Patients present with straw-colored urine discharge from the umbilicus, which is exacerbated by crying, straining, or prone position. Local skin irritation can cause erythema. Failure to close the distal part of the urachus (adjacent to the umbilicus) results in a urachal sinus. This presents with periumbilical tenderness and purulent umbilical discharge due to persistent and recurrent infection. Failure of the central portion of the urachus to obliterate leads to a urachal cyst. (Choice A) Leukocyte adhesion deficiency involves decreased expression of the neutrophil cell-surface adhesion proteins, β-2 integrins. As a result, neutrophils are less adherent to the vascular endothelium and fail to migrate toward infected sites. There is delayed separation of the umbilical cord (>1 month), omphalitis, and leukocytosis (unlike this patient, who has a normal white count and differential for his age). (Choice B) A duplication of the renal collecting system can affect the pelvicalyceal system, the ureters, or both. The insertion of the ureter can be normal (in the trigone) or abnormal (in the urethra, vagina, or uterus). It does not involve the umbilicus. (Choice C) Gastroschisis results from inadequate enlargement of the peritoneal cavity in utero. The viscera protrude through an abdominal wall defect adjacent to the umbilicus. Viscera are not covered by peritoneum. (Choice E) Meckel diverticulum results from failure of obliteration of the vitelline (or omphalomesenteric duct). Toddlers may have painless gastrointestinal bleeding due to ectopic gastric mucosa. Educational objective: The urachus is a remnant of the allantois that connects the bladder with the yolk sac during fetal development. Failure of the urachus to obliterate at birth results in a patent urachus, which can facilitate discharge of urine from the umbilicus. __________ References: Her belly button is leaking: a case of patent urachus. (http://www.ncbi.nlm.nih.gov/pubmed/25370310)

A 3-Week-Old Boy with Discharge from the Umbilicus Is Brought