OMPHALOMESENTERIC (VITELLINE) REMNANT

 

OMPHALOMESENTERIC (VITELLINE) REMNANT

Partial or complete failure of involution of the omphalomesenteric duct can lead to a spectrum of anomalies in the newborn infant due to varying degrees and location of duct patency:

A.   An umbilical cyst containing intestinal tissue.

B.   Umbilical sinus with a band.

C.   A persistent omphalomesenteric duct at the umbilicus with no intestinal connection results in an umbilical polyp.

D.   Patent mid-duct with closure at both the umbilical and ileal ends of the omphalomesenteric duct results in an omphalomesenteric duct cyst. Because the two ends are fixed, this can lead to small bowel obstruction if loops of bowel twist around the cyst.

E.   Persistent tissue at the ileum, with no connection to the umbilicus results in Meckel's diverticulum.

F.   Complete patency results in the omphalomesenteric duct directly connecting the umbilicus to the terminal ileum. This can lead to intermittent drainage from the umbilicus " omphalomesenteric fistula". These infants will often appear to have a "stoma" in the umbilicus after cord separation.

G.  Persistent fibrous cord (band)  between the umbilicus and the ileum, which can lead to small bowel obstruction.

Meckel's diverticulum

 

Meckel's diverticulum

Meckel diverticulum is the most common congenital anomaly of the GI tract and is caused by the incomplete obliteration of the omphalomesenteric duct during the 7th wk of gestation.

Meckel diverticulum has been conveniently referred to by the “rule of 2s,”:

• Occurs in 2% of the population.
• Appears within 2 feet (50-75 cm) of the ileocecal valve.
• approximately 2 inches in length
• Approximately 2% to 4% of patients develop complications over the course of their lives.
• Typically presents before age 2 years.
• Two-thirds of patients with MD have 2 types of heterotopic mucosa (gastric and pancreatic), although colonic heterotopic mucosa has also been reported.
•  Is twice as likely to be symptomatic in boys than girls

Meckel diverticulum is typically lined by ileal mucosa.

Clinical presentations:

The majority are asymptomatic.

It is often found incidentally on imaging studies.

Hematochezia:

• Cause of bleeding is ectopic gastric mucosa (acid-secreting mucosa)
• Intermittent painless rectal bleeding (hematochezia) occurs suddenly and tends to be massive in younger patients.
• Bleeding occurs without prior warning and usually spontaneously subsides.
• The color of the stool is typically described as brick colored or currant jelly colored.
• Bleeding can cause significant anemia but is usually self-limited (resolves without intervention) because of contraction of the splanchnic vessels, as patients become hypovolemic.
• Bleeding from a Meckel diverticulum can also be less dramatic, with melanotic stools.

It should be suspected in children with recurrent or atypical intussusception, a patient with symptoms of appendicitis after their appendix has been removed, and patients with an unclear source of GI bleeding.