Alimentary tract duplications take many forms, and one unifying embryologic theory is unlikely to encompass all variations. The associated findings of vertebral, spinal cord, and genitourinary (GU) malformations, as well as malrotation and intestinal atresia, suggest a multifactorial process in their development. ^{, ,} There are five prevailing theories: partial twinning, split notochord, diverticular defects, canalization defects, and environmental factors. The partial twinning theory states that organs can be doubled as a result of partial twinning. This theory may be pertinent in hindgut duplications associated with GU tract duplications. ^, The split notochord theory centers around notochord separation in the first month of gestation. This theory postulates that gaps in the notochord develop and allow gut endoderm to herniate and form diverticula. This theory could account for the association of duplications with spinal defects. A persistent embryonic diverticulum from the gastrointestinal (GI) tract was the first theory described in the literature, and a defect in lumen canalization was proposed years later. The theory of defective canalization is based on the finding that GI organs begin as solid tubes and vacuolate to form lumens. During this process, diverticula form but regress during fetal life. If they persist, duplications could form. ^, Finally, environmental factors including hypoxia, vascular accidents, and trauma have been implicated in the development of these anomalies. ^,

GI duplications are found incidentally, or they can manifest with a wide range of symptoms, including abdominal distention, pain, obstruction, intussusception, bleeding, perforation, respiratory compromise, or as a painless mass. Generally, symptoms are related to size, location, and the presence of heterotopic mucosa. With advances in prenatal imaging, many of these masses are being diagnosed in utero ( Fig. 37.1 ) and the majority are discovered before 2 years of age. ^{, ,} A recent study from the Children’s Hospital of Philadelphia (CHOP) found that 58% of duplications were diagnosed prenatally over a 25-year period. The majority of duplications are cystic ( Fig. 37.2 ), and the remaining are tubular ( Fig. 37.3 ). The ileum and jejunum are the most commonly affected locations, followed by the esophagus. The epithelial lining is usually native to the surrounding enteric tract, but heterotopic mucosa is found in approximately one-third of duplications. Gastric tissue is the most common type of ectopic mucosa, followed by pancreatic tissue, and there are reports of respiratory epithelium being found as well ( Fig. 37.4 ). Ectopic gastric mucosa can lead to peptic ulceration with subsequent hemorrhage, anemia, or perforation ( Fig. 37.5 ). Pressure necrosis from an adjacent duplication can also lead to hemorrhage or perforation. Associated anomalies are described in approximately 20%, with the most common anomalies being malrotation, intestinal atresia, spinal anomalies, and GU anomalies. Although duplications are benign, the potential for malignant degeneration remains a concern.

This T2–weighted transverse MRI image was obtained from a 22-week gestational age fetus. The white arrow identifies a hyperintense cystic-like structure that is a gastric duplication protruding through the native gastric wall.

From Laje P, Flake AW, Adzick NS. Prenatal diagnosis and postnatal resection of intraabdominal enteric duplications. J Pediatr Surg . 2010;45:1554–1558. Reprinted with permission.

Most alimentary tract duplications are cystic. In this laparoscopic photograph, note the cystic duplication being grasped by the Maryland instrument. Its blood supply can be seen just below the tip of the instrument. As opposed to a Meckel diverticulum, which is found on the antimesenteric side of the bowel, duplications are located on the mesenteric side.

This operative photograph shows a child with a tubular colonic duplication ( solid arrow ). The duplications are always on the mesenteric side of the native colon. In this photograph, the cecum is marked by the asterisk and the native colon is identified with the dotted arrow .

Photo courtesy Dr. Michael Rollins.

These two histologic images were taken from a tubular jejunal duplication. On the left (A) the low-power image shows two lumens that are separated by a singular muscular wall. On the right (B), the medium-power image shows the gastric mucosa from the duplication ( left ) and the small intestinal mucosa with villi from the native jejunum ( right ).

Photo courtesy Dr. Walter Pipkin. From Cunningham AJ, Ham PB, King, RG, et al. Congenital jejunal tubular duplication in a patient with a congenital thoracic meningocele. Am Surg . 2015;81:E332–E333.

This infant presented with abdominal distention and free air. Laparotomy was performed, and this perforation on the antimesenteric side of the distal small bowel was seen. The perforation occurred due to the duplication cyst located on the mesenteric border ( asterisk ). This patient underwent segmental small bowel resection and recovered uneventfully.

Multiple imaging modalities are utilized to make the diagnosis. Prenatal ultrasound (US) can be followed with US postnatally, which may be sufficient, especially for distal small bowel lesions. The typical sonographic appearance of a duplication (the double-wall sign) demonstrates a cystic rim of hyperechoic serosa and an inner hyperechoic rim of mucosa and submucosa with a hypoechoic muscular layer sandwiched between the two hyperechoic layers ( Fig. 37.6 ). For foregut lesions, more information in the form of computed tomography (CT) or magnetic resonance imaging (MRI) may prove valuable in operative planning. Plain radiographs may reveal a mediastinal mass, which requires further workup with either CT or MRI. Contrast studies may show a mass effect or communication with the alimentary tract and can help with the diagnosis, particularly in hindgut and foregut lesions. Technetium-99m scintigraphy may be used as adjuvant imaging but is likely unnecessary in most cases. ^, The presence of a vertebral abnormality and a duplication is best investigated with MRI to evaluate communication with the spinal canal.

Ultrasonography is a frequent imaging modality for diagnosing abdominal duplications. The typical sonographic appearance of a duplication demonstrates a cystic lesion with an inner hyperechoic rim of mucosa and submucosa ( dotted arrow ) and an outer rim of hyperechoic serosa ( solid arrow ) with a hypoechoic muscular layer between them. In this image, inspissated mucous ( asterisk ) is also seen.

To better understand the wide presentation and surgical treatment of duplications, they are best discussed according to anatomic location. A compilation of major case series reported in the last 75 years from 23 different institutions is given in Table 37.1 . ^{, , , , ,} The goal of operative management is to remove the duplication, but the surgical procedure should not be more radical than necessary to eliminate the patient’s complaints and prevent recurrence. Simple cyst resection without violating the native GI tract is one option, but because most share a common blood supply to the native alimentary tract, resection with primary anastomosis is often needed and curative, depending on the location.

In the recent CHOP 25-year review, bowel resection was required in 34% of cases. Long tubular, thoracoabdominal, and gastroduodenal duplications may present a more difficult challenge as resection can carry significant morbidity. Partial excision with mucosal stripping may be the best option in these situations. Overall prognosis is favorable, but associated malformations, location, and presenting illness can factor into the final outcome.

Esophageal Duplications

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