The word atresia etymologically comes from the Greek a, which means no or without, and tresis, which means orifice.
Jejunoileal atresias and stenoses are major causes of neonatal intestinal obstruction. Atresia refers to a congenital obstruction with complete occlusion of the intestinal lumen. It accounts for 95% of obstructions. Stenosis, on the other hand, refers to a partial occlusion with incomplete obstruction and accounts for the remaining 5% of cases.
Intestinal atresia or stenosis can occur anywhere along the GI tract, and the anatomic location of the obstruction determines the clinical presentation. Most newborns with intestinal obstruction present with bilious emesis. Bilious vomiting in the neonate should be considered secondary to a mechanical obstruction until proven otherwise, and emergency surgical evaluation is warranted in every newborn with this symptom.
The survival of patients with intestinal obstruction has markedly improved over the last 20 years because of an improved understanding of intestinal physiology and the etiologic factors of the condition, refinements in pediatric anesthesia, and advances in surgical and perioperative care of newborns.
History of the Procedure
Ileal atresia has long been recognized. The first description of ileal atresia was credited to Goeller in 1684. In 1911, Fockens reported the first successful surgical repair of a patient with small intestinal atresia.[2, 1] However, the mortality rate for the surgical correction of this condition remained high for many years, even in the best pediatric surgical centers.
In 1955, Louw and Barnard demonstrated the role of late intrauterine mesenteric vascular accidents as the likely cause of jejunoileal atresias, rather than the previously accepted theory of inadequate recanalization of the intestinal tract. Since that time, other factors such as in utero intussusception, intestinal perforation, segmental volvulus, and thromboembolism have also been shown to cause jejunoileal atresia. Atresias can also develop in patients with gastroschisis and in those with meconium ileus.
Congenital duodenal obstruction may be complete or partial, intrinsic, or extrinsic. Intrinsic atresias or stenoses have an incidence of about 1 in 7000 live births and account for about half of all small intestinal atresias. Extrinsic obstruction has many causes, including malrotation with Ladd bands, other congenital bands not associated with malrotation, preduodenal portal vein, gastroduodenal duplications, cysts or pseudocysts of the pancreas and biliary tree, and annular pancreas. Annular pancreas is commonly associated with an intrinsic cause of duodenal obstruction.
In West Africa, intestinal atresia is the fourth most common cause of neonatal intestinal obstruction after anorectal malformations, Hirschsprung disease, and strangulated inguinal hernias. In an 11-year retrospective review of 500 children in India, Ranan et al found intestinal atresias to be the most common cause of intestinal obstruction in newborns and the second most common cause (11.8%) after intussusception (20.8%) in all age groups.
Boys and girls are equally affected. In most studies, jejunoileal atresias seem to be more common than duodenal atresias, and colonic atresias account for the fewest number of cases.
Unlike duodenal atresia, jejunoileal atresia associated with Down syndrome is uncommon. Patients with intestinal atresia are epidemiologically characterized by young gestational age and low birth weight, the atresia is associated with twinning, the parents are more often consanguineous compared with parents of healthy neonates, and vaginal bleeding frequently complicates the pregnancies. No correlation between jejunoileal atresia and parental age or disease has been proven.[11, 12, 4] However, one study in France showed an increased prevalence of intestinal atresias in infants born to teenagers. Some maternal infections may be associated with ileal atresia.
Intrinsic duodenal obstructions and annular pancreas result from events that occur during early development of the foregut. Duodenal atresia and stenosis are believed to result from a failure of recanalization of the embryonic duodenum, which becomes solid as a result of early epithelial proliferation. Annular pancreas occurs when the ventral pancreatic bud fails to rotate behind the duodenum, leaving a nondistensible ring of pancreatic tissue fully encircling the second portion of the duodenum. Annular pancreas frequently coexists with intrinsic duodenal anomalies and anomalies of the pancreaticobiliary ductal system, suggesting closely linked mechanisms of pancreatic, duodenal, and biliary development during this stage.
The higher prevalence of associated congenital malformations with duodenal atresia compared with jejunoileal atresia suggests that proximal obstructions occur earlier in fetal life.[13, 14]
Unlike duodenal atresia, many jejunoileal atresias are separated by a cordlike segment or a V-shaped mesenteric gap. This finding and the usual finding of bile pigments and lanugo hairs distal to the atretic segment indicate that an in utero vascular accident that occurs relatively late in gestation (>11-12 weeks’ gestation) is likely the origin of these atresias, rather than failure of GI tract recanalization. A localized intrauterine vascular accident with ischemic necrosis of the bowel and subsequent reabsorption of the affected segment is the favored theory.[15, 3, 2, 1, 16] de Chadarevian et al (2009) reported on an infant with inherited thrombophilia creating a hypercoagulable state, favoring a segmental intestinal thrombosis and resulting in terminal ileal atresia. This patient was also found to have Hirschsprung disease, which is rarely associated with intestinal atresias.
The localized nature of a vascular insult explains the low prevalence (10%) of coexisting conditions. Intestinal atresia associated with in utero intussusception or perforation, malrotation, volvulus, internal hernias, gastroschisis, and omphalocele further corroborates a vascular event as the etiology of most jejunoileal atresias.[18, 16, 19, 20]
Only one case of a newborn patient has been reported to date with multiple intestinal atresias associated with multifocal angiodysplasia of the intestinal wall.
Sweeney et al examined 38 patients with jejunal atresia and 45 patients with ileal atresia at the Children's Research Center in Dublin, Ireland. Compared with patients with ileal atresia, patients with high jejunal atresia had a higher rate of associated congenital malformations (42% vs 2%), had a higher rate of multiple or apple-peel (type IIIb) atresias (53% vs 9%), and had a higher mortality rate. These results suggest that jejunal atresia may also develop from a malformative process.
In a collaborative study in France, Gaillard et al reviewed 102 cases from 42 induced abortions and 22 stillborns, as well as surgical findings in 38 neonates. Abnormalities such as meconium ileus (associated with cystic fibrosis) and chromosomal aberrations (eg, Down syndrome) were present during the second trimester of gestation. Intestinal atresia and stenosis were detected in the third trimester of pregnancy and were associated with ischemic conditions.
Most infants with this condition have only a single atretic segment. However, multiple atresias have been described in infants of mothers who ingested ergotamine and caffeine, or pseudoephedrine alone or in combination with acetaminophen during pregnancy.[23, 24] Other vasoconstrictive factors such as cocaine abuse and smoking during pregnancy have also been associated with increased risk for the development of intestinal atresia. Also, the risk is higher in patients with graft versus host disease and immunosuppression and in those with malformative processes that are likely due to autosomal recessive transmission.[25, 26]
Multiple intestinal atresias have been reported in rare association with pyloric atresia and pylorocholedochal fistula.
In a study of 114 cases of jejunoileal atresia in the Netherlands, Stollman et al found other gastrointestinal anomalies in 24% of patients, genitourinary malformations in 9%, cystic fibrosis in 9%, neurologic anomalies in 6%, and congenital heart disease in 4%.
Duodenal obstructions of congenital origin are often associated with other congenital anomalies, which account for most of the morbidity and mortality in these patients. Various reports put the incidence of associated conditions between 50-80%. Congenital heart disease and trisomy 21 are the most common associated conditions, each occurring in about 30% of cases. All three conditions may coexist in the same patient.
Among patients with trisomy 21 who underwent prenatal ultrasonography, about 4% were found to have prenatal evidence of duodenal atresia. Other associated anomalies include intestinal malrotation (20%), esophageal atresia, or imperforate anus (10-20%), thoraco-abdominal heterotaxia, and gallbladder agenesis. One of the most important aspects to keep in mind, as in other neonatal diseases, the outcome for patients with duodenal atresia depends more on the severity of these associated anomalies and the ease with which they can be corrected than on the surgical management of the obstruction itself.
Familial cases of various types of atresia have been well described. Familial type I jejunal atresia affected 3 members from 2 generations in one family. Proximal atresia was associated with renal dysplasia. Knowledge of the familial form of the disease indicates that most cases of jejunoileal atresia actually result from disruption of a normal embryologic pathway, most likely the development of the superior mesenteric artery and its branches. They should be considered to be true embryologic malformations rather than acquired lesions.
This association is presumably an autosomal dominant condition. Matsumoto et al reported a case in Japan and reviewed the literature, finding 6 other cases of small intestinal atresia occurring in twins. All published cases except one involved identical twins. Three pairs of twins had different types of atresia, and 4 pairs did not have any other anomalies. The other members of these families were not affected; this finding suggested that such cases may be due to environmental influences during gestation.
Another report of different intestinal atresias in identical twins proposes them to be either the consequence of linkage of two genes or a pleiotropic expression of a single gene.
As stated above, the patophysiology of dudoenal stenosis/atresia is different that the ones located more distal in the Jejuno-ileal area; this cannot be overstated. In duodenal atresias, a failure of recanalization of intestinal tube occurs at 8-10 weeks' gestation after obliteration of the lumen by epithelial proliferation (6-7 weeks' gestation); it usually occurs in the second part of the duodenum. Incomplete recanalization can lead to duodenal stenosis or the presence of a duodenal web.
However, jejunoileal atresias occur because of an ischemic injury to the gut, usually secondary to malrotation with volvulus or intestinal strangulation with the umbilical ring, intestinal perforations, or vasoconstrictive drugs (eg, cocaine, ephedrine, nicotine). Jejunoileal atresias occur after intestinal development because of the presence of bile droplets, meconium or lanugo distal to the atresia.
Dalla Vecchia et al performed a 25-year retrospective review and found 277 neonates with intestinal atresia. The level of obstruction was duodenal in 138 patients, jejunoileal in 128, and colonic in 21. Of the 277 neonates, 10 had obstruction at more than one site. Jejunoileal atresia was associated with intrauterine volvulus (27%), gastroschisis (16%), and meconium ileus (11.7%).
In atresias of the small intestine, the jejunum and ileum are equally affected.[9, 38, 1] The proximal jejunum is the site of atresia in 31% of cases, the distal jejunum in 20%, the proximal ileum in 13%, and the distal ileum in 36%. In more than 90% of patients, the atresia is single; however, multiple atresias are reported in 6-20% of cases.[39, 1]
Stollman et al (2009) published one of the largest series of jejunoileal atresias as a retrospective review at a large pediatric referral center in the Netherlands. Between 1974 and 2004, they found 114 infants with jejunoileal atresia. Sixty-two percent of atresia and stenosis cases were noted in the jejunum, 30% in the ileum, and 8% in both the jejunum and the ileum. Seven percent of patients had intestinal stenosis, 16% had type I atresia, 21% had type II, 24% had type IIIa, 10% had type IIIb, and 22% had type IV.
Heij et al performed a retrospective analysis of 21 patients with jejunal atresia and 24 with ileal atresia and found more differences than similarities between the groups (see Table). The mean birth weight and gestational age were significantly lower in patients with jejunal atresia than in those with ileal atresia. Most jejunal atresias were multiple, whereas most ileal atresias were single. Antenatal perforation occurred frequently (10 cases) in ileal atresia but infrequently (2 cases) in jejunal atresia. The postoperative course was often prolonged, and the mortality rate increased in patients with jejunal atresia, among whom three deaths occurred (all in patients with apple-peel deformity). By comparison, one patient with ileal atresia died.
Heij et al suggested that a difference in compliance of the bowel wall between the jejunum and ileum may explain some of their findings. The compliant jejunal wall allows for massive dilatation with subsequent loss of peristalsis, accounting for the prolonged postoperative course and the relatively high rate of perforation in ileal atresias.
Table. Differences Between Jejunal and Ileal Atresia[40, 11, 1, 12, 4, 41]
|Characteristic||Jejunal Atresia||Ileal Atresia|
|Gestational age||Lower than that of ileal atresia||Low|
|Birth weight||Lower than that of ileal atresia||Low|
|Atresias||May be multiple||Simple|
|Mortality||Higher than that of ileal atresia||Low|
The maximal dilatation of the proximal segment occurs at the point of obstruction. This segment is commonly aperistaltic, of questionable viability, or both. Grosfeld et al have modified Louw’s original classification into the following most commonly used description of intestinal atresia:
- Type I – Membrane
- Type II – Blind ends joined by fibrous cord
- Type IIIa – Disconnected blind end
- Type IIIb – Apple-peel deformity
- Type IV – Multiple, string of sausages
The proximal dilated intestine is in continuity with the distal nondilated bowel, and the mesentery is intact. Between these portions, a narrow, semirigid segment with a minute lumen is present. The small bowel length is normal. This lesion might simulate an atresia type I (see the image below).
[/i]Intestinal stenosis. Dilated prestenotic bowel is in continuity with the distal intestine. No mesenteric gap is present. Bowel length is normal. Atresia type I (membrane)
This type is a mucosal (septal) atresia with an intact bowel wall. The proximal dilated intestine is continuous with the distal narrow one. The mesentery is intact, and the intestinal length is normal. The pressure generated on the internal membrane may elongate it as a windsock, giving a conical appearance to the transition. The distal intestine is collapsed (see the image below) but may contain meconium.
[/i]The transition area has a conical appearance due to windsock elongation of the membrane in atresia type I. No mesenteric gap is present. Bowel length is normal. Atresia type II (blind ends joined by a fibrous cord)
In this type, a fibrous cord separates the proximal bowel from the distal segment. The mesentery is usually intact, but a small, V-shaped defect may be present. The length of the intestine is normal. The proximal blind pouch is grossly dilated, often aperistaltic and cyanotic. In addition, perforations have been encountered in patients who present late. Dilatation usually extends proximally 10-15 cm, after which the intestine assumes a relatively normal appearance. The distal blind pouch may be mildly distended because of retained cellular debris (as in fetal intussusception) (see the image below).
[/i]Intestinal atresia type II. The proximal dilated bowel is separated from the distal narrow one by a fibrous cord, in this case, without a mesenteric gap. Bowel length is normal. Atresia type III
Type III atresias seem to be the most common.[9, 10] Intrauterine resorption of fetal gut subjected to a vascular insult explains the reduced bowel length commonly seen in this type of atresia. The distal bowel is small and decompressed.
Atresia type IIIa (disconnected blind ends)
In this type of atresia, both blind ends are completely separated without a fibrous cord between them. The atresia has a V-shaped mesenteric gap, and the intestine is shortened (see the image below). The proximal dilated pouch may have questionable viability and undergo torsion.
[/i]Intestinal atresia type IIIa. Both blind ends are separated completely. A V-shaped mesenteric gap is present. Intestinal length is shortened. Atresia type IIIb (apple-peel deformity)
This type of atresia is also called the Christmas-tree deformity. Both intestinal segments are separated as in type IIIa, and the mesenteric defect is large. The proximal atretic segment is in the upper jejunum, near the ligament of Treitz, and the pouch is distended and lacks dorsal mesentery. The superior mesenteric artery distal to the middle colic branch is absent. The collapsed distal intestine helically encircles a small vessel (marginal artery) that arises from the ileocolic or right colic arcades, or the inferior mesenteric artery, and its vascularity may be impaired.
Type I or type II atresias may coexist in the distal segment. The intestine is always substantially shortened (see the image below). Many patients with this variant have low birth weight (70%) and were born premature (70%); they may also have malrotation (54%), multiple atresias, and an increased number of other associated anomalies that increase the prevalence of complications (63%) and mortality rate (54-71%).[42, 1, 43]
[/i]Intestinal atresia type IIIB (apple-peel or Christmas-tree deformity). The proximal pouch is dilated. The collapsed distal intestine encircles the marginal artery helically. Intestinal length is substantially reduced. Atresia type IV (multiple atresia)
Type IV atresia refers to any number and combination of atresias type I to III that present simultaneously, creating a string-of-sausages appearance (see the image below). A possible cause is intrauterine inflammation. However, findings of this type of atresia in family members suggest possible autosomal recessive transmission.[44, 39, 26]
[/i]Intestinal atresia type IV. Multiple atresias appear simultaneously as a string of sausages. The intestinal length is invariably and considerably shortened. The presence of multiple GI atresias with cystic dilatation of the bile duct is rare; the association has been described in 37 patients, with no recorded survivors in the world literature.[33, 45] The dilatation of the bile duct seems to be due to normal drainage of bile into a closed-loop duodenal obstruction. Patients present with multiple atresias and die from short-bowel syndrome and complications related to total parenteral nutrition (TPN).
Jejunoileal atresias can be identified on the basis of polyhydramnios present during prenatal ultrasonographic evaluation, bilious vomiting, abdominal distension, and jaundice. Some patients may not pass meconium in the first day of life.
The clinical presentation of the infant with congenital duodenal obstruction depends on the presence or absence of a membranous aperture, its size, and the location of the obstruction relative to the ampulla. The classic presentation of a complete postampullary obstruction that includes bilious vomiting within 24 hours of birth in an otherwise stable infant with a nondistended abdomen.
Plain radiographs of the abdomen typically show the classic double-bubble sign: 2 distinct gas collections or air-fluid levels in the upper abdomen, resulting from the markedly dilated stomach and proximal duodenal bulb. If the infant’s stomach has been decompressed by vomiting or previous nasogastric aspiration, 30-60 mL of air may be carefully injected through the nasogastric tube, and the double-bubble sign reproduced. Air makes an excellent contrast agent, obviating a barium or water-soluble contrast study in routine cases.
The distal intestinal tract may be gasless or may contain a small amount of intraluminal air due to a membranous aperture or perforation, or an anomalous bile duct with openings on both sides of the obstructing diaphragm.
Clinical presentation of patients with jejunoileal atresia is as follows:
- Common characteristics
- Polyhydramnios on prenatal ultrasound (28%)
- Prematurity (35%)
- Low birth weight (25-50%)
- Polyhydramnios on prenatal ultrasound (28%)
- Classic signs
- Bilious emesis that warrants emergent surgical evaluation (most patients)
- Abdominal distention (in distal atresias)
- Jaundice (32%)
- Failure to pass meconium in the first 24 hours (Rule out Hirschsprung disease. Passage of meconium does not rule out intestinal atresia.)
- Bilious emesis that warrants emergent surgical evaluation (most patients)
- Signs of continuous fluid loss
- Dehydration, manifested by sunken fontanel and dry membranes
- Decreased urine output (best clinical indication of tissue perfusion)
- Decreased pulse pressure
- Low-grade fever
- Neurological involvement, manifested by irritability, lethargy, or coma
- Dehydration, manifested by sunken fontanel and dry membranes
Most patients present with bilious emesis, which indicates that the obstruction is distal to the ampulla of Vater.
The patient's pulse, respiratory rate, blood pressure, and temperature are usually initially within the reference range. As the patient loses fluid into the bowel and by vomiting, diminished plasma volume is reflected as tachycardia, decreased pulse pressure, and, sometimes, low-grade fever.
Immediately after delivery, the patient appears relatively healthy. Over time, the patient develops signs of hypovolemia (sunken eyes, sunken fontanel, dry skin and mucous membranes, and prolonged capillary refill time), which are due to vomiting and intra-abdominal third-space loss secondary to the obstruction. These patients are hungry and properly suck milk; however, they cannot tolerate feedings and continue to vomit profusely. They eventually become lethargic and hyporeactive, with muscle flaccidity. They can develop skin mottling, cardiovascular instability, and neurological involvement (irritability or coma).
A proximal small-bowel obstruction results in loss of fluids that resemble gastric juice and thus produces hypokalemic and hypochloremic metabolic alkalosis. With distal small bowel obstruction, fluid losses are usually isotonic, so serum electrolytes are normal until sufficient dehydration results in metabolic acidosis, as demonstrated by tachypnea, low serum bicarbonate levels, and elevated serum chloride values.
Adequate tissue perfusion is evaluated by observing the patient's capillary refill time, pulse, blood pressure, and urine output. If the patient is severely dehydrated, tenting of the skin can be noted.
About 32% of infants with jejunal atresia and 20% of those with ileal atresia have jaundice, which is characteristically due to indirect hyperbilirubinemia.
Abdominal distension is most evident in cases of ileal atresias, in which it is diffuse, as opposed to proximal jejunal atresias, in which the upper abdomen is distended and the lower abdomen is scaphoid.
[/i]Plain abdominal radiograph of a newborn patient with a distal type IIIA ileal atresia, demonstrates diffuse small bowel (and gastric) distension, with gasless pelvis. Courtesy of Rodrigo Díaz, MD. Intestinal loops and their peristalsis may be seen through the thin abdominal wall of newborns.
These babies’ abdomens are usually soft, without signs of peritonitis. In utero perforations usually seal before delivery. However, an excessively dilated proximal segment may undergo torsion, necrosis, and/or perforation. In these cases, the patient appears septic and dehydrated, and the abdominal wall may be discolored.
The patient's ability to pass some meconium does not exclude intestinal atresia. Cellular debris and swallowed amniotic fluid and lanugo hairs form meconium, explaining this finding; this formation occurs earlier in gestation than the insult that produces the atresia.
Upon laboratory examination, an elevated hematocrit level secondary to hemoconcentration due to reduced plasma and extracellular fluid volume loss may be detected. The WBC count may be either normal or elevated. Patients may present with indirect hyperbilirubinemia and the electrolyte disturbances mentioned above.
The importance of differentiating intrinsic duodenal obstruction from intestinal malrotation with a midgut volvulus in the infant who presents with bilious vomiting cannot be overstated. A clue may be derived from the appearance of the duodenum on the plain radiograph. In the classic double-bubble sign, the duodenum appears distended and round because of chronic intrauterine obstruction. When a distended stomach is associated with a normal-caliber duodenum, the diagnosis of malrotation with duodenal obstruction secondary to Ladd bands or volvulus must be entertained.
In an unstable patient, echocardiography and contrast studies may be required to distinguish hemodynamic compromise caused by volvulus from that caused by cardiac disease. Even when the diagnosis of duodenal atresia is established in the stable patient, cardiac anatomy and function should be evaluated before surgical correction.
Atresias should be distinguished from other causes of neonatal intestinal obstruction. Meticulous history taking and physical examination are the most useful elements in differentiating these conditions. Clinical settings and paraclinical studies to support the decision-making process are mentioned. The following are differential diagnoses of jejunoileal atresia and the indicated study associated with them:
- Malrotation with or without midgut volvulus – Contrast-enhanced upper-GI study
- Meconium ileus – Contrast-enhanced enema
- Intestinal duplication – Contrast-enhanced study, ultrasonography
- Internal hernia – Intraoperative examination
- Colonic atresia – Visual inspection (which reveals diffuse distension)
- Colonic aganglionosis – Rectal Biopsy
- Adynamic ileus – Examination (which reveals sepsis) and electrolyte disturbances
Meconium peritonitis, due to in utero intestinal perforation, can be revealed using plain abdominal imaging. It appears as calcifications throughout the peritoneal cavity.
Patients with Hirschsprung disease are not usually premature or small for gestational age. A transition zone can be revealed using a barium enema study if enough time to develop high intraluminal pressure and proximal dilatation has passed. Rectal biopsy findings are diagnostic.
Ileal atresia and Hirschsprung disease are individually frequent causes of intestinal obstruction. However, the association of both these diseases is an extremely rare event. Only 19 such cases have been reported in the literature.
Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a rare congenital disorder and the most common cause of functional intestinal obstruction in the newborn. This condition is associated with a grossly dilated nonobstructed urinary bladder, microcolon, and decreased or absent intestinal peristalsis. Most cases occur in females (70%), and 227 cases have been reported in the world literature between 1976-2011. Survival rate is 20% with some patients reaching adulthood with TPN maintenance or multivisceral organ transplantation. Mortality is related to sepsis, malnutrition, and multiple organ failure.