Monday 26 May 2008

Gastrointestinal Duplications

Gastrointestinal duplications are rare congenital malformations that may vary greatly in presentation, size, location, and symptoms.
Problem
In 1733, Calder published the first report of an intestinal duplication. In 1937, Ladd introduced the term duplication of the alimentary tract. This condition consists of a group of congenital anomalies with the following 3 characteristics:
A well-developed coat of smooth muscle is present.
The epithelial lining represents some portion of the alimentary tract.
Duplications are frequently intimately attached to some portion of the gastrointestinal tract.

Frequency
Gastrointestinal duplications are observed in 1 of every 4500 autopsies, predominantly in white males. The small intestine is the most frequent site involved, whereas gastric, duodenal, rectal, and thoracoabdominal involvement is relatively rare. Synchronous gastrointestinal duplications occur in as many as 15% of patients.
Cervical duplications: Cervical esophageal duplication cysts are the most unusual gastrointestinal duplication, with fewer than 10 cases reported.
Thoracic and thoracoabdominal duplications: These make up 4% of all gastrointestinal duplications.
Gastric duplications: These duplications account for 7% of all gastrointestinal duplications.
Pyloric duplications: These are extremely rare. However, they are reported in the literature.1
Duodenal duplications: These account for 5% of all gastrointestinal duplications.
Small-intestine duplications: The small intestine is the most frequent site of gastrointestinal duplications, accounting for 44% of cases.
Colonic duplications: They may be cystic or tubular; colonic duplications represent 15% percent of duplications.
Rectal duplications: These represent up to 5% of gastrointestinal duplications.

Etiology
The true etiology of gastrointestinal tract duplications is not known. Several theories have been postulated. The idea that the initial developmental abnormality occurs in the gastrulation stage and results in a split notochord has been proposed. During early embryogenesis, the notochord is open, and the endoderm of the yolk sac and the ectoderm of the notochord are fused; a tube called the neuroenteric canal connects the yolk sac and the amnion. As part of the development of the split notochord, an endodermal-ectodermal adhesion between the cord has been proposed to result in the persistence of an endomesenchymal tract between the yolk sac and the amnion. The endomesenchymal tract formed is responsible for the anomalies of the entire gastrointestinal system. However, not all duplications are compatible with this theory, and other etiologies have been proposed.
Some duplications of the foregut and hindgut may occur as a result of "partial twinning." These duplications may be associated with other paired structures, such as those found in the genital and urinary tract. Other duplications, especially those of the ileum, may occur as a result of persistent embryological diverticula. Some portions of the intestinal tract have a solid stage during development; therefore, duplications of these structures may result from "aberrant luminal recanalization." Finally, intrauterine environmental factors, such as trauma or hypoxia during a vascular accident, may cause duplications at any level of the gastrointestinal tract.

Clinical
Presentation depends on the size and location of the duplication.
Cervical duplications: Patients with cervical duplications present with respiratory distress that may be life-threatening and requires rapid diagnosis and treatment.
Thoracic and thoracoabdominal duplications: Respiratory distress caused by airway compression may be noted in younger children; however, in older patients, heartburn or melena has been reported, which is probably caused by the presence of gastric mucosa in one third of patients with thoracic and thoracoabdominal duplications.
Gastric duplications: Patients usually present when younger than 1 year with vomiting, poor feeding, failure to gain weight, and a palpable mass upon physical examination. Hypertrophic pyloric stenosis is often a misdiagnosis in such infants. The mucosal lining of the cysts is often gastric and can lead to melena or hematemesis.
Duodenal duplications: Fifteen percent of these duplications contain ectopic gastric mucosa, which predisposes the patient to ulceration. Peptic ulceration may lead to painless gastrointestinal hemorrhage that can progress to perforation. Duplications may extend into the liver or even transdiaphragmatically. These are generally diagnosed after onset of high intestinal obstruction or hemorrhage that may commonly be accompanied by icterus or pancreatitis.
Small-intestine duplications: Clinical presentation depends on the type, size, location, and mucosal lining of the duplication. Small cystic duplications can be anchor points for intussusception or can result in volvulus, whereas long tubular duplications with proximal communication drain poorly, and retention of intestinal contents can obstruct adjacent intestine. Distal communication is more common and is more difficult to diagnose than proximal communication. Gastric mucosa in a duplication can lead to ulceration and perforation. The diagnosis is often not established before surgery.
Colonic duplications
Cystic colonic duplications are either asymptomatic or present as abdominal masses that may be accompanied by pain. Bleeding may be observed despite the lower prevalence of ectopic gastric mucosa in colon duplications. Newborns may present with volvulus or acute intestinal obstruction.
Tubular colonic duplications are usually asymptomatic, but severe esthetic problems are observed with the duplicated genitalia.
Rectal duplications: Presenting signs of colonic or presacral duplications may include constipation, rectal bleeding, hematochezia, rectal prolapse, hemorrhoids, fistula-in-ano, and perirectal abscess.

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Grey Matter - from the writers of Grey's Anatomy