KEY POINTS
- 1.
The processes leading to duodenal atresia and distal atresia are unknown but reflect a general defect in intestinal development. In the past, duodenal atresia was thought to result from failure of recanalization of the duodenal lumen, but there is little basis to support this theory. In animals, vascular occlusion causes intestinal changes that look similar to intestinal atresia, but there is little evidence to indicate that intestinal atresia in humans follows vascular accidents. For reasons that are unknown, duodenal atresia has a high association with other congenital anomalies.
- 2.
A “double bubble” sign seen on x-ray (which reflects air within the stomach and duodenum) or on prenatal ultrasound (which reflects accumulated fluid within these two compartments) can be diagnostic for duodenal atresia. Presence of distal air can distinguish complete versus partial obstruction.
- 3.
Bilious emesis in the newborn should raise immediate suspicion for malrotation and requires prompt evaluation and intervention.
- 4.
The upper gastrointestinal series is the accepted standard for diagnosis of malrotation; however, if midgut volvulus is suspected, emergent surgery without imaging is warranted.
- 5.
Abdominal wall defects can be diagnosed prenatally and should be referred to tertiary care centers where immediate access to pediatric surgical consultation is available.
- 6.
Omphaloceles are highly associated with congenital anomalies, particularly cardiac and chromosomal, whereas gastroschisis is not.
Introduction
Disorders of the intestine that require surgery in the newborn may evolve from an array of congenital or functional disorders. These often present as complete or partial obstructions, which may result from intrinsic and extrinsic pathology. Findings such as bilious emesis, abdominal distention, or failure to pass meconium are signs of obstruction, and learning to quickly identify the location and underlying nature of these disorders is essential, because conditions such as volvulus may require emergent surgery. In addition, disorders of the abdominal wall present unique challenges in surgical and medical management. This chapter focuses on the more common indications for intestinal surgery in the newborn, specifically intestinal atresia, malrotation, meconium ileus, and duplication cysts as well as abdominal wall defects, gastroschisis, and omphalocele.
Intestinal Atresia
Pathophysiology
Intestinal atresia is the most common cause of obstruction in the neonate, affecting approximately 1.6 per 10,000 newborns, with duodenal atresia making up approximately 60%. Although all forms of intestinal atresia result from some anomaly in normal embryonic development, the clinical implications vary based on their anatomic locations.
Duodenal atresia occurs most commonly as an error in early embryonic development. In the past, it was thought that duodenal development required a series of complex proliferation followed by recanalization steps and that failure to recanalize in the proximal gut results in the obstruction or stenosis. However, there is little evidence to support this notion, and it is more likely that duodenal atresia reflects an error in the complex steps that underlie normal intestinal development. For reasons that are not well understood, there is a high association with cardiac and urogenital anomalies, VACTERL (vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities), and other GI anomalies such as malrotation, annular pancreas, esophageal atresia, and imperforate anus. Approximately 30% of cases are associated with trisomy 21, and 3% to 8% of trisomy 21 patients are born with atresia. , Duodenal atresia is classified into three main categories, shown in Table 83.1 .
| Duodenal Atresia | Jejunoileal Atresia | |
|---|---|---|
| Type 1 | A mucosal membrane occludes the duodenal lumen, usually at or near the level of the ampulla of Vater. It can be completely occlusive (1A); fenestrated, allowing passage of air and contrast distal to the second “bubble” (1B); or a variant in which the membrane is elongated with the apex located distal to its origin, known as a “windsock anomaly” (1C). | A mucosal web forms within the bowel, causing luminal obstruction. No resulting loss of intestinal length. |
| Type 2 | Proximal and distal duodenal segments end blindly with an intervening fibrous cord connecting them. | There is a gap in luminal continuity with a connecting cord-like scar or band connecting the proximal and distal bowel. The mesentery remains intact between the discontinuous bowel. |
| Type 3 | Type 3 is the rarest subtype, often associated with annular pancreas; the atretic proximal and distal ends end blindly with absence of intervening mesentery. | In type 3, a gap exists between the proximal and distal small intestine and there is a mesenteric defect. |
| Type 3b | In type 3b, a large section of bowel supplied by the distal superior mesenteric artery is absent and the distal section of ileum is shortened and coiled in a spiral around a vascular stalk from the ileocolic artery—so-called apple peel atresia. It usually results from a midgut volvulus in the setting of intestinal malrotation | |
| Type 4 | Multiple gaps in intestinal continuity exist, often a combination of type 2 and type 3 defects. This can result in a very short length of functional small bowel. |
Jejunoileal atresia may occur anywhere in the remainder of the small bowel. In elegant experiments on dogs, vascular occlusion resulted in the development of intestinal changes that mimic atresia, although there is little evidence that ischemic insult acquired in utero during fetal development occurs in patients with atresia. Although some researchers have hypothesized that the affected bowel becomes necrotic and subsequently involutes and resorbs, leaving blind proximal and distal ends with a widely varied extent of involved or absent bowel, there is no evidence for necrosis or involution in patients with atresia. In-utero volvulus, internal hernia, and even in-utero intussusception may occur, leading to broad disruption of the gastrointestinal (GI) tract, but these are distinct entities from the commonly seen instances of intestinal atresia. In select cases, arterial vasoconstriction or thrombosis precipitated by maternal smoking, drug use, medications, or inherited thrombophilias have been thought to play a role, although the vast majority of cases of intestinal atresia lack any identifiable risk factor for thromboembolic disease. Similar to duodenal atresia, patterns of jejunoileal atresia have been classified into four main groups (see Table 83.1 ).
Colonic atresia is the least common location, and its etiology is unknown. It may be seen in conjunction with small-intestinal atresia and can be associated with Hirschsprung disease and gastroschisis.
Clinical Features
Prenatal diagnosis of intestinal atresia is increasingly common with improvements in sensitivity of ultrasound; however, fewer than half of patients are diagnosed before birth. Sonographic signs include polyhydramnios and dilatation of the proximal small bowel with distal decompression. Sensitivity increases with more proximal lesions, because the bowel becomes more distended with swallowed amniotic fluid that the short proximal segment is unable to fully absorb. Duodenal atresia classically exhibits a “double bubble” sign with distention of the stomach and first portion of the duodenum and is the most commonly discovered prenatally, whereas colonic atresia is infrequently prenatally diagnosed unless more proximal involvement is also present. ,
Postnatally, infants will present with signs of intestinal obstruction including persistent or forceful emesis and abdominal distention; however, this varies by location and extent of involved bowel. Duodenal atresia will result in gastric distention and early emesis that may be bilious depending on the location of the atresia in relation to the ampulla of Vater. Passage of meconium is common in these infants. Neonates with jejunoileal atresia will typically have increased abdominal distention and bilious emesis within the first 2 days of life and usually will not pass meconium. Colonic atresia exhibits the most distended abdomen because the entire bowel may fill with air and enteric contents, and it tends to present the latest.
Evaluation
Prenatal suspicion (polyhydramnios, sonographic double bubble) or postnatal signs of obstruction (persistent emesis, abdominal distention) should trigger further evaluation for intestinal atresia including history, physical exam, and family history of associated congenital anomalies. The timing and onset of distention and emesis, presence or absence of bilious emesis, and passage of meconium should be noted and the abdomen assessed for tenderness and distention. Peritonitis may suggest the presence of intestinal perforation or compromised bowel. Inspection for associated congenital anomalies should be performed. Basic chemistry labs may reveal associated metabolic derangements secondary to persistent emesis.
Abdominal x-ray is generally the first imaging study to further assess the extent and pattern of intestinal dilatation and presence of free air or pneumatosis, which would prompt urgent operative exploration. The “double bubble” sign on plain film with gasless distal bowel is again seen in duodenal obstruction due to air-filled gastric and duodenal dilatation; however, this may not be seen in very proximal atresia. Findings of distal gas with a “double bubble” sign are more consistent with a partial duodenal obstruction or more rarely can be seen with anomalous bile duct anatomy. More distal obstruction will again exhibit a dilated proximal bowel with air fluid levels and decompressed gasless distal bowel. Colonic atresia will show dilated colonic loops, often with a ground-glass or soap-bubble appearance on plain radiograph. Preoperative screening echocardiography and head and abdominal ultrasound are performed to assess for associated anomalies that may affect timing of any planned intervention. Malrotation with or without midgut volvulus can mimic atresia, and an upper GI water-soluble contrast study should be performed emergently if the diagnosis is in doubt. This test may also demonstrate the location of atresia for preoperative planning. Contrast enema may also be performed to elucidate the extent and location of distal atresia and will often demonstrate a microcolon due to lack of use, as well as inability to advance contrast into the dilated proximal loops.
Management
Antenatal suspicion for intestinal atresia warrants transfer of care to a center with availability of pediatric surgical consultation. Initial postnatal management includes withholding of feeds and prompt placement of a decompressive nasogastric tube to prevent aspiration. Infants with significant emesis or enteric tube output are susceptible to dehydration and electrolyte abnormalities and should receive intravenous resuscitation and electrolyte replacement. Broad-spectrum intravenous antibiotics are started for sepsis prophylaxis against GI bacterial translocation and for perioperative prophylaxis.
Definitive management is surgical in all types of intestinal atresia, with the principles being relief of obstruction and restoration of continuity while preserving functional bowel and minimizing long-term complications. The operative approach differs by anatomic location and subtype, however. Multiple techniques have been described to repair duodenal atresia since its initial report by Ladd in 1931, including duodenojejunostomy, side-to-side duodenoduodenostomy, and partial web excision; however, the current standard described by Kimura is the diamond-shaped duodenoduodenostomy. The dilated duodenum is mobilized, and a handsewn anastomosis is performed between a transverse incision in the dilated proximal duodenum and a longitudinal incision in the distal duodenum. This technique was found to have earlier anastomotic function and lower long-term stricture rates. Certain cases of type 1 duodenal atresia may be amenable to simple excision of the duodenal web through an anterior duodenotomy; however, great care must be taken to identify and preserve the ampulla of Vater, as it is generally located at the same level as the web. Gentle compression of the gallbladder may aid in identification of the ampulla by visualization of bilious output in the duodenum. Some infants—typically those with extremely low birth weight—may benefit from a duodenojejunostomy due to its relative technical ease, and this is our strong preference. Laparoscopic repair of duodenal atresia is increasingly being used, and in experienced hands, long-term outcomes compared with open have been similar and with shorter hospital stays and time to advancement to full feeds.
Atresia of the jejunum is less amenable to laparoscopic repair due to obscuring distention of multiple loops of small bowel and is generally treated with an open approach. The atretic area or areas are identified and resected with primary end-to-end or end-to-side anastomosis. In very small or unstable infants with distal small bowel atresia, an end ileostomy or jejunostomy with mucous fistula may be performed with subsequent delayed bowel anastomosis at 2 to 4 months of age. Primary web excision through an enterotomy for type 1 lesions are seldom performed given the risk for recurrence and stricture.
Colonic atresia may develop into a closed loop obstruction if an intact ileocecal valve is present, and emergent surgical consultation is necessary. Colonic atresia is mostly treated with resection of atretic bowel and either primary anastomosis or staged anastomosis depending on the overall stability of the patient.
Due to the increased risk of multiple sites of atresia, saline or air should be injected intraoperatively into the distal bowel to detect additional sites of obstruction. Size mismatch of proximal and distal segments is an expected occurrence that may complicate primary anastomosis and lead to dysmotility. It is important to resect the proximal bowel for some distance to optimize motility and function. Tapering enteroplasty may be used in cases in which the intestine is very dilated, and it involves a longitudinal resection of the antimesenteric portion of the proximal dilated bowel to equilibrate the two sides of the anastomosis. We perform the tapering enteroplasty over a large red rubber catheter and use stapling devices to remove the antimesenteric dilated bowel. Concomitant anomalies requiring additional procedures at the time of the initial operation are also common. Those infants with intestinal malrotation should undergo a Ladd’s procedure with appendectomy at initial presentation, and those with imperforate anus should undergo initial temporary colostomy.
Long-Term Outcomes
Although postoperative complications are common after correction of intestinal atresia, overall long-term outcomes are quite good if treated promptly and appropriately. Postoperative adhesive bowel obstructions and anastomotic strictures can occur and may warrant reoperation. Other common perioperative complications include prolonged ileus, anastomotic leak, wound infection, late adhesive bowel obstruction, and colostomy prolapse and retraction. Duodenal atresia has 0% to 4% operative mortality and up to 10% overall mortality, mostly attributable to comorbid congenital anomalies including complex cardiac anomalies. , Jejunoileal atresia has a low association with complex cardiac malformations and therefore has low early mortality (<1%); however, it has greater overall major morbidity and mortality (16% overall in-hospital mortality) related to an increased extent of resection and complications of intestinal failure and sepsis. , Colonic atresia, if diagnosed early, has excellent prognosis with survival to discharge approaching 100% ; however, outcomes become significantly worse with delayed diagnosis and progression to gangrene and perforation. In long-term follow-up, patients with intestinal atresia grow up to have quality of life similar to that of healthy controls, with major differences attributed largely to associated conditions such as trisomy 21 and not to decreased GI quality of life.
Malrotation and Volvulus
Pathophysiology
Intestinal malrotation results from an arrest in the normal rotation of the gut during embryonic development. The GI tract undergoes rapid growth and expands outside of the coelom into the yolk stalk during weeks 4 to 8. It begins its normal rotation with a 90-degree counterclockwise turn about the axis of the superior mesenteric artery and then returns to the abdominal cavity in the 8th to 10th week of gestation to continue a further 180-degree rotation before its fixation to the posterior abdomen. The end result of this 270-degree turn is the cecum fixed in the right lower abdomen and the duodenum fixed in the left upper abdomen with a broad base of mesentery separating the two fixation points.
Various errors in normal rotation may occur, from complete nonrotation to reverse rotation of part or all of the embryonic gut. Complete nonrotation leaves the small intestine on the right side of the abdomen and the colon on the left, leaving a wide mesenteric base, and therefore there is low risk of volvulus. Malrotation, however, results in a nonrotated duodenojejunal limb with partial rotation of the cecum located in the upper mid-abdomen with a narrow mesenteric base that is susceptible to midgut volvulus and strangulation, its most feared complication. The cecum also has peritoneal attachments, called Ladd’s bands, to the right lateral abdominal wall that overlie and compress the duodenum, causing duodenal obstruction.
Clinical Features
Intestinal malrotation is thought to occur in 1 in 500 live births based on autopsy studies; however, only 1 in 6000 lead to clinical presentation. The true incidence is unknown because many remain asymptomatic. Those that do present with symptoms may do so at any time from infancy to adulthood; however, approximately 30% to 50% occur within the first month of life and 70% within the first year of life. Intestinal volvulus is the most feared complication and can result in life-threatening intestinal ischemia and necrosis; however, more benign presentation with duodenal obstruction due to compression from overlying Ladd’s bands may occur. Bilious emesis is typically the first sign in infants and should trigger immediate suspicion for malrotation, but nonbilious emesis may also occur, especially with proximal duodenal obstruction. Abdominal distention and tenderness may be present with midgut volvulus and may progress to hemodynamic instability, peritonitis, and hematochezia in cases of threatened or necrotic bowel. Patients with malrotation may have associated congenital anomalies, most commonly diaphragmatic hernia, complex cardiac anomalies, and abdominal wall disorders. Heterotaxia disorders have associated malrotation in 40% to 90% of cases. , Older children may present with acute volvulus as well but often have a more insidious onset of chronic abdominal pain, intermittent bilious or nonbilious emesis, failure to thrive, malabsorption, motility disorders, or chylous ascites.
Evaluation
Due to the potential for life-threatening intestinal volvulus, clinicians must have a high level of suspicion for any of the signs of malrotation mentioned above. Any infant with bilious emesis, duodenal obstruction, or abdominal tenderness with hemodynamic changes or with nonbilious emesis in the setting of a known associated congenital anomaly should be treated as having intestinal volvulus until proven otherwise and undergo emergent evaluation and/or intervention. Hemodynamic instability with peritonitis requires no further workup and should undergo emergent surgical exploration to address potential threatened or necrotic bowel. In the absence of such hard signs, workup should begin with a plain abdominal film, which is nonspecific for malrotation, but it will show the bowel gas pattern and evaluate for free intraperitoneal air. Additionally, plain film may show a nasoenteric tube placed in a malpositioned duodenum or a double bubble sign indicating duodenal obstruction. In the hemodynamically stable infant, a fluoroscopic upper GI series with small bowel follow-through remains the imaging gold standard for diagnosis of malrotation. A misplaced duodenum with the ligament of Treitz to the right of midline and a corkscrew appearance of the proximal bowel is suggestive of malrotation; however, any abnormal placement of the duodenojejunal junction can be suspicious for malrotation. Duodenal obstruction seen on upper GI may mimic duodenal atresia; however, a tapering bird’s beak at the point of obstruction is suggestive of volvulus. In centers with experienced radiologists, upper GI studies have sensitivity up to 96% for detecting malrotation ; however, results may be subtle or inconclusive, with a false-positive rate up to 15%. Useful radiologic studies to assist in diagnosis include ultrasound to assess the location of the duodenum in relation to the mesenteric vessels and “swirling” of the vessels in cases of volvulus. The location of the cecum may not correlate with disorders of rotation, although in the past, barium enema was used to assess the location of the cecum. Diagnostic laparoscopy or laparotomy may be required to make a definitive diagnosis in the absence of definitive radiologic studies if clinical suspicion is high enough.
Management
The definitive treatment for intestinal malrotation and associated intestinal volvulus and duodenal obstruction is the Ladd’s procedure. Its goal is not to restore normal intestinal anatomy but rather to reduce the risk of obstruction, volvulus, and devastating intestinal necrosis. Preoperatively, the patient is resuscitated, a decompressive nasogastric tube is placed, and broad-spectrum perioperative antibiotics are administered. Symptomatic patients should be taken emergently to the operating room due to the risk of volvulus and its potentially devastating sequelae.
Ladd’s procedure involves exploration of the abdominal cavity to confirm the abnormal anatomy, reduction of any volvulus if present, division of the Ladd’s bands that tether the cecum to the right lateral abdominal wall and duodenum if present, widening the base of the mesentery by incising the peritoneum to gain length between the arcades of the superior mesenteric artery, and prophylactic appendectomy due to the abnormal position of the appendix and the risk for subsequent atypical presentation of appendicitis. The bowel must be fully examined for areas of injury or necrosis, with resection and possible ostomy versus primary anastomosis if nonviable bowel is found. Temporary closure may be employed with subsequent return for a second look if areas of questionable viability are present. Complete nonrotation of the intestine carries a low risk of volvulus because the mesenteric base is typically wide; however, distinguishing nonrotation from malrotation is difficult without direct visualization, so exploration and appendectomy are indicated in most cases.
Historically, the open laparotomy with the Ladd’s procedure was felt necessary for formation of adhesions to secure the bowel in a position of nonrotation to prevent recurrent volvulus. Newer evidence has since emerged supporting the role of laparoscopic Ladd’s procedure in the treatment of malrotation. , Operative times and rates of recurrent volvulus appear to be equivalent between open and laparoscopic approaches, and laparoscopy is associated with lower rates of postoperative bowel obstruction and overall complication rates as well as a shorter hospital stay. The laparoscopic approach to Ladd’s procedure is a safe and effective option in experienced hands.
The approach to the asymptomatic child with radiographic signs of intestinal malrotation remains controversial, especially when discovered outside the neonatal period. Elective exploration is generally indicated in cases of incidentally diagnosed malrotation in a neonate due to the high morbidity associated with potential volvulus. Most cases of volvulus occur in infancy and the risk is thought to decrease with age, but the true natural history of the disease is not well known because many patients remain asymptomatic for life. In the presence of a documented malrotation, diagnostic laparoscopy with Ladd’s procedure is a safe and effective option.
Long-Term Outcomes
Outcomes after Ladd’s procedure for malrotation are largely dependent on the presence of volvulus and necrotic bowel. Those without necrotic bowel have an excellent prognosis with survival approaching 100%, and most deaths are associated with congenital cardiac disease. Of the 40% of neonates who present with midgut volvulus requiring intestinal resection, long-term outcomes are based on the extent of resection and remaining bowel function. Those requiring >75% resection of small bowel are at high risk of subsequent intestinal failure and mortality. Additional morbidity after Ladd’s procedure include postoperative ileus, adhesive small bowel obstruction, and anastomotic leak and stricture. Rates of recurrent volvulus are low (approximately 0%–5%) and do not appear to be different in a laparoscopic versus open approach. ,
Meconium Ileus
Meconium ileus (MI) is a cause of neonatal bowel obstruction primarily seen in patients with cystic fibrosis (CF). It is the earliest manifestation of CF and results from luminal obstruction by inspissated meconium that adheres to the wall of the bowel, typically in the distal ileum, although the entire intestinal tract may be involved. Mutations in the CF transmembrane conductance regulator gene ( CFTR ) result in desiccation and thickening of intraluminal mucus due to errors in electrolyte transport across the mucous membrane. The majority of cases of MI are CF related; however, some isolated series report rates as high as 46% without positive CF testing, signifying additional contributors that may also influence this disease process. ,
Clinical presentation typically includes abdominal distention, feeding intolerance, emesis, and failure to pass meconium within 24 to 48 hours. MI is classified as complex if there are associated GI complications including bowel necrosis, intestinal perforation, meconium peritonitis, atresia, or volvulus. Up to 40% of patients with CF present with complex disease, whereas it is exceedingly rare in non-CF patients.
As CF carrier testing becomes more common and fetal ultrasound improves, prenatal diagnosis of MI has become more common. Ultrasound findings include dilated small bowel, hyperechoic intraluminal meconium masses, or peritoneal calcifications in the case of perforation and meconium peritonitis. Suspicious ultrasound findings should prompt parental CF screening, and those with confirmation of CF or continued abnormal ultrasound findings should be referred to a tertiary pediatric care center with pediatric surgical expertise. Postnatally, abdominal x-ray will also reveal dilated intestinal loops, possible signs of perforation such as free air, or peritoneal calcifications. Contrast enema is the next step in evaluation for patients without signs of perforation and may show diminutive colon and meconium pellets in the distal ileum. Infants with suspected MI should undergo definitive testing for CF.
As in any case of neonatal bowel obstruction, initial management includes fluid and electrolyte resuscitation, nasogastric decompression, and prophylactic broad-spectrum antibiotics. Preservation of intestinal function and nutritional support is of critical importance for CF patients, and a conservative first-line approach in management in MI is recommended. Infants with simple MI confirmed on diagnostic enema should undergo therapeutic enema using hyperosmotic contrast under fluoroscopic guidance, which may be performed serially, drawing fluid into the lumen to soften and break up inspissated meconium. Addition of N-acetylcysteine may increase efficacy. Operative intervention is indicated for infants with complex MI or those who fail nonoperative management, with goals of disimpaction of inspissated meconium, restoration of luminal continuity, and conservation of functional bowel length. Several approaches have been employed to allow for continued postoperative irrigation, including tube enterostomy, proximal or distal chimney enterostomy, and Mikulicz double-barreled enterostomy, with resection of any necrotic or nonfunctional bowel if necessary. Resection with intraoperative meconium evacuation and primary anastomosis is also an option; it immediately restores full bowel continuity but does not allow further local irrigation and may have higher leak rates. Postoperatively, enteral feeds should be advanced as soon as tolerated, with pancreatic enzyme replacement therapy in patients with pancreatic dysfunction. Ostomy reversal is generally performed by 6 weeks to 2 months from the time of surgery but is dependent on the patient’s clinical status.
With improvements in neonatal intensive care, nutritional support, infection prevention, and nonoperative and operative interventions, prognosis has become quite good for patients with MI, with survival approaching 100%. Long-term pulmonary outcomes and overall survival are equivalent between patients with CF and without MI and between those treated for complex versus simple disease.
Meconium plug syndrome is a disease process that also presents in the neonatal period with obstruction due to inspissated thickened meconium; however, it is considered to be a separate entity from MI. Meconium plugs generally occur in the colon rather than the ileum, and approximately 30% resolve without any intervention whereas nearly all (97%) resolve with hyperosmotic contrast enema. It is associated with Hirschsprung disease in up to 38% of cases, and although there does appear to be an association with CF, it is highly variable in the literature (0%–43%) with possible confusion in discriminating plug from ileus in older data. ,
Duplication Cysts
Duplication cysts are cystic or tubular structures composed of intestinal remnants that share a muscular layer and mesenteric blood supply with the adjacent bowel but have separate mucosal layers. These contain epithelium of the associated bowel, or ectopic (gastric) or respiratory epithelium. Duplication cysts are uncommon, reported in 1 in 4500 by autopsy reports. The exact etiology is unknown, but one prominent theory is the split notochord theory. During the third week of gestation, the notochord appears and grows cephalad with the endoderm. As the notochord separates from the endoderm, a band between them causes a traction diverticulum, which develops into the duplication cyst. These can occur anywhere along the alimentary tract from the mouth to the anus but most commonly occur in the small intestine.
Clinical presentation is widely variable based on size, location, and presence of gastric mucosa. These can cause obstructive symptoms through external compression or as lead points for intussusception or a segmental volvulus. Gastric duplications may present with vomiting or poor feeding. Duodenal duplications may cause jaundice or pancreatitis. Ectopic gastric mucosa can secrete acid, causing ulceration of adjacent bowel and leading to GI bleeding or perforation. Children with duplication cysts have a higher incidence of associated anomalies including spinal malformations, intestinal atresias, malrotation, or urinary tract anomalies in midgut and hindgut duplication cysts. This incidence is higher for those with multiple duplications. ,
Duplication cysts can often be detected with pre- or postnatal ultrasound; however, determining the origin is not always possible. Computed tomography or magnetic resonance imaging are not generally indicated but are useful to further characterize duodenal duplications. If intestinal bleeding is present, a Meckel scan may be useful to identify ectopic gastric mucosa.
Surgical excision of duplication cysts is recommended to prevent complications of obstruction, bleeding, or infection. Complete resection is the goal; however, the size and location may prohibit complete resection without significant morbidity such as esophageal, gastric, duodenal, or long-segment intestinal lesions. Partial resection with stripping of the mucosa may be necessary in these cases. Duodenal lesions present a unique challenge because most are located on the medial side of the second portion of the duodenum, and intraoperative cholangiography with internal drainage may be indicated to avoid injury to the biliary system. Cystic duplication cysts on the small intestine are located on the mesenteric border and require a segmental bowel resection with primary anastomosis. Examination for additional synchronous cysts should be performed, because synchronous duplication cysts can be seen in 20% of cases. Tubular cysts on the small intestine can involve long segments, and complete resection would lead to short-gut syndrome. Partial resection of the seromuscular wall with stripping of the mucosa along the length of the duplication, or creating openings between the duplication cyst and adjacent bowel, are preferable alternatives to complete resection. Outcomes from duplication cyst resections are generally excellent but depend largely on the location and extent of the resection required. Recurrences can occur if the cysts were incompletely excised.
Abdominal Wall Defects
Pathophysiology
Omphalocele and gastroschisis are clinically distinct abdominal wall defects. Omphalocele results from an error in embryonic development leading to failure of the cephalic, caudal, and/or lateral folds to close the abdominal wall defect, typically by the 10th week of gestation. , Loops of intestine, stomach, and liver may herniate through the defect, but these are contained within a membranous sac ( Fig. 83.1 ). There is a high association with other anomalies, particularly cardiac and chromosomal disorders. Failure of the cephalic fold is associated with pentalogy of Cantrell (cleft sternum, diaphragmatic defects, pericardial defects, cardiac anomalies, and omphalocele), whereas failure of the caudal fold is associated with lower abdominal defects (bladder exstrophy, cloacal exstrophy, and imperforate anus).
