A 3-year-old boy is brought to the emergency department by his parents after he develops acute abdominal pain and vomiting. Examination shows diffuse tenderness to palpation, and abdominal imaging reveals a foreign body lodged within the intestine, causing a small bowel obstruction. Laparotomy is performed to remove the foreign body; during the procedure, an incidental cyst is discovered. The cyst is connected by a fibrous band to the ileum and the umbilicus. The embryologic defect underlying the formation of this patient's cyst is also associated with which of the following?

Question

A 3-year-old boy is brought to the emergency department by his parents after he develops acute abdominal pain and vomiting.  Examination shows diffuse tenderness to palpation, and abdominal imaging reveals a foreign body lodged within the intestine, causing a small bowel obstruction.  Laparotomy is performed to remove the foreign body; during the procedure, an incidental cyst is discovered.  The cyst is connected by a fibrous band to the ileum and the umbilicus.  The embryologic defect underlying the formation of this patient's cyst is also associated with which of the following?

Quizplus · Accepted Answer

11ec160b_3743_4775_9249_1b74941b1639_MD0001_00 This patient has an abnormal fibrous connection between the ileum and the umbilicus, a finding that represents the incomplete obliteration of the vitelline (omphalomesenteric) duct. Normally, the vitelline duct connects the midgut lumen with the yolk sac cavity in early fetal development and obliterates in the first trimester. In this case, the incidental cyst within this embryologic remnant is consistent with a vitelline duct cyst. Incomplete obliteration can result in a spectrum of anomalies: Persistent vitelline duct is due to the complete failure of duct closure and results in a patent connection between the intestinal lumen and the umbilicus. This causes meconium discharge from the umbilicus after birth. Meckel diverticulum, the most common vitelline duct anomaly, results from partial closure of the vitelline duct, with the patent portion attached to the ileum. A fibrous band may connect the tip of the diverticulum with the umbilicus. Patients classically have painless hematochezia due to intestinal ulceration from heterotopic gastric mucosa contained within the diverticulum. Vitelline sinus results from partial closure of the vitelline duct, with the patent portion at the umbilicus; serous umbilical drainage may occur. Vitelline duct cyst, as seen in this patient, forms when peripheral portions of the duct obliterate but the central part remains. Patients are usually asymptomatic. (Choices A, D, and F) Gastroschisis and omphalocele are characterized by the incomplete closure of the abdominal wall, leading to protrusion of abdominal organs. Whereas gastroschisis occurs lateral to the umbilicus and eviscerated bowel is exposed, omphalocele is a midline defect covered within a peritoneal sac. An umbilical hernia, a common midline protrusion, is due to abdominal wall weakness. These defects are not associated with a vitelline cyst. (Choice B) Malrotation results from failure of the midgut to rotate normally while it returns to the abdominal cavity during early fetal development. Patients have abnormal positioning of the intestine in the abdominal cavity and sometimes twisting of an intestinal loop (volvulus). (Choice E) A patent urachus results from failure of the allantois (urachus) to obliterate and presents with urine drainage through the umbilicus. This anomaly is associated with a urachal cyst, which is connected by a fibrous band to the bladder (not the ileum) and umbilicus. Educational objective: The vitelline (omphalomesenteric) duct normally obliterates during early embryologic development. Incomplete obliteration can result in a spectrum of anomalies, including vitelline duct cyst (ie, cyst connected by fibrous bands to the ileum and umbilicus) and Meckel diverticulum.

A 3-Year-Old Boy Is Brought to the Emergency Department by His