Congenital Duodenal Obstruction: Atresia, Stenosis, and Annular Pancreas

Abstract

Congenital duodenal obstruction, whether complete or partial, occurs due to intrinsic and extrinsic problems during the development of the foetal duodenum; however, it is most often caused by intrinsic duodenal atresia or stenosis. This review will discuss the epidemiology, aetiologies, and classification of congenital duodenal obstruction. The diagnostic approach will be outlined for patients with suspected duodenal obstruction. The therapeutic approach with details of the surgical repair will also be reviewed in light of the best available clinical evidence. The early and late postoperative complications will be discussed as well as the need for reoperation. Outcomes following surgical repair were reviewed.

1. Introduction

The duodenum is one of the most common sites of congenital neonatal intestinal obstruction. Although causes of duodenal obstruction were recognized as early as the eighteenth century, the first successful treatment of duodenal atresia was described by Vidal from France in 1905. Since then, major advances in surgical and neonatal care have resulted in greater than 90% survival.

2. Epidemiology

The incidence of duodenal atresia is approximately 1 in 5000–10,000 live births, and it affects boys more than girls [1]. More than 50% of affected children have other associated anomalies, most commonly trisomy 21 (30% of duodenal atresia cases), heterotaxy syndrome, and congenital cardiac defects [2, 3]. Other less common associations include annular pancreas, malrotation, oesophageal atresia, genitourinary anomalies, anorectal malformation, and concomitant intestinal atresia [4].

3. Aetiology

Congenital duodenal obstruction occurs due to intrinsic or extrinsic mechanisms. The most common causes of intrinsic duodenal obstruction are atresia and stenosis. Intestinal embryogenesis involves rapid epithelial proliferation that results in lumen obliteration during the sixth week of gestation. This is followed by recanalization through vacuolization to re-establish the intestinal lumen in the 11th week of gestation. Failure in this step is believed to be the cause of duodenal atresia and stenosis. This is different from the principal cause of atresia in other parts of the small bowel, which is believed to result from vascular accidents [5].

Extrinsic compression of the duodenum causing obstruction occurs due to malformation of adjacent structures such as annular pancreas, preduodenal portal vein, or intestinal malrotation [6]. Annular pancreas is a condition where there is an error in the rotation and fusion of the ventral and dorsal buds of the developing pancreas during the 4–8th weeks of gestation (Figure 1). This often leads to the formation of a ring of pancreatic tissue encircling and obstructing the second part of the duodenum [5]. It is not totally agreed upon whether the annular pancreas actually causes duodenal obstruction from external compression or whether the malformed pancreas is just concomitant to true duodenal atresia [7]. In cases of annular pancreas with duodenal obstruction, the bile duct anatomy is often variable, with the ampulla of Vater located either above or below the level of duodenal obstruction [8, 9, 10].

Figure 1.

A–D show the stages of the development of annular pancreas encircling the duodenum.

4. Classification

Duodenal obstruction can be either compete (atresia) or partial (stenosis or perforate web). Although intrinsic obstruction can occur at any level in the duodenum, nearly 85% of these patients have obstructions at the junction between the first and second parts of the duodenum. The ampulla of Vater is commonly located proximal to the obstruction, which occurs in 85% of the cases, with the common bile duct often traversing the medial aspect of the obstructing septum, a critical anatomical consideration during surgical repair [6, 11].

Gray and Skandalakis classified duodenal atresia into three types (Figure 2) [12]:

Figure 2.

Classification of duodenal atresia. (A) type 1, (B) type 1 with windsock variant, (C) type 2, and (D) type 3.

Type 1 (over 90% of cases): There is an obstructing septum, web, or diaphragm formed from mucosa and submucosa with an intact mesentery (Figure 2A). A variant of this anomaly is a “windsock deformity” where the septum is thin and stretches distally in the duodenum. Therefore, externally, the obstruction appears to be more distal than its true location (Figure 2B) [13].

Type 2 (1% of cases): There are proximal dilated and distal collapsed portions of the duodenum, and both are connected by a fibrous cord with an intact mesentery (Figure 2C).

Type 3 (7% of cases): There is no connection between the two ends of the duodenum with a V-shaped mesenteric defect (Figure 2D).

5. Clinical presentation

Prenatally, maternal polyhydramnios is often detected in 30–65% of cases [14]. Sonographic evidence of two fluid-filled structures (double bubble) in the foetal abdomen can be visualized in approximately 44% of cases of congenital duodenal obstruction. These findings are often detected in the last trimester. Interestingly, the antenatal diagnosis of congenital duodenal obstruction has been found to decrease both pre- and postoperative complications [15, 16, 17, 18].

Postnatally, the clinical presentation depends on whether the obstruction is complete or incomplete. With complete obstruction, the newborn will present with persistent bilious vomiting in the majority of cases. In approximately 10% of the cases where the obstruction is preampullary, the newborn’s emesis will be nonbilious [19]. Due to the proximal nature of the obstruction, the abdomen is usually not distended. However, gastric fullness may be appreciated on a clinical examination [20]. In cases of incomplete duodenal obstruction, e.g., stenosis, the child will often present later with repeated emesis, feeding intolerance, and possibly failure to thrive.

6. Investigations

Once duodenal obstructions is suspected, a plain abdominal radiograph is usually sufficient to make the diagnosis. Typically, a double-bubble sign with no distal abdominal air is seen (Figure 3). The first bubble to the left represents the gastric air, while the right bubble represents air within a dilated proximal duodenum [21]. Distally, the abdomen is almost always gasless in complete duodenal obstruction, except in cases of incomplete obstruction or the rare cases of bifid common bile duct associated with duodenal atresia [22]. Upper GI contrast studies are usually not necessary unless incomplete obstruction or malrotation is suspected. To assess for concomitant congenital cardiac malformation, echocardiography should be performed.

Figure 3.

Abdominal X-ray showing double-bubble sign with no distal air in patient with duodenal atresia.

7. Treatment

After the diagnosis of duodenal obstruction is established, a nasogastric tube should be inserted to decompress the stomach. Fluid resuscitation and electrolyte correction are important as well as monitoring the newborn’s blood glucose level. Due to the expected delay in feeding postoperatively, we highly recommend placement of a peripherally inserted central catheter (PICC) for parenteral nutrition. Corrective surgery is not emergent unless malrotation is suspected.

Surgical treatment for duodenal atresia is duodenoduodenostomy to bypass the area of obstruction. The operation is classically performed via a right upper transverse laparotomy incision. Since the introduction of minimally invasive surgery, laparoscopy has been increasingly utilized for the repair of duodenal atresia with excellent outcomes [23, 24, 25, 26, 27, 28, 29]. Originally, side-to-side anastomosis was performed; however, diamond-shaped duodenoduodenostomy was introduced by Kimura and was found to result in better outcomes, namely, earlier feeding, fewer anastomotic strictures, and better duodenal emptying [30, 31, 32]. After the abdomen is entered, the colon is mobilized to expose the duodenum. Associated malrotation should be ruled out at this step. The proximal dilated duodenum is easily mobilized. Other causes of duodenal obstruction, such as annular pancreas or preduodenal portal vein, may become obvious. The distal collapsed duodenum should be mobilized enough to gain length for a tension-free anastomosis. Before opening the duodenum, the surgeon should consider the windsock phenomenon. This phenomenon can be verified by asking the anaesthetist to push the nasogastric tube into the duodenum and observe the duodenal wall indentation, which marks the origin of the obstructing septum [13]. A transverse duodenotomy is made in the anterior wall of the distal part of the proximal duodenum with a similar length longitudinal duodenotomy made into the distal collapse duodenum. A diamond-shaped anastomosis is then constructed (Figure 4). The anastomosis should be tension-free and with an acceptable calibre. A tapering duodenoplasty is not routinely performed unless there is a concern about the emptying of a very dilated proximal duodenum [33, 34]. Some surgeons advocate the use of a transanastomotic feeding tube with the aim of early initiation of enteral feeding and limiting the use of parenteral nutrition [35, 36]. However, there are no well-designed prospective studies to examine the potential benefit of the use of transanastomotic feeding tube in duodenal atresia patients [37].

Figure 4.

Diamond-shaped duodenoduodenostomy.

The laparoscopic approach to correct duodenal atresia was first described by Bax in 2000, and since then, it has gained wide popularity [23, 24, 25, 26, 28, 29]. Three ports are usually needed. Liver retraction can be achieved by a transabdominal suture to retract the falciform ligament to better expose the duodenum. The anastomosis is performed using the standard technique. When compared with the open technique, several reports suggested an earlier feeding time and shorter time for parenteral nutrition and hospitalization after laparoscopic repair; however, there are no randomized controlled trials to support these findings [27, 38, 39].

Postoperatively, the newborn is monitored in the intensive care unit. Gastric decompression is continued until the output decreases and becomes less bilious. Until then, parenteral nutrition is provided via the PICC line. Contrast studies are not routinely required prior to the initiation of enteral feeding. The average length of hospital stay after duodenal atresia repair is approximately 23–33 days [40, 41]. In the era of enhanced recovery after surgery (ERAS), compelling evidence suggests that a well-designed ERAS protocol might result in earlier initiation of feeding and a shorter hospital stay without an increase in complications after repair for duodenal atresia [42].

8. Postoperative complications

Early complications: By far, the most common complication in the early postoperative period is feeding intolerance. Typically, gastrointestinal function may take days to weeks following repair of duodenal atresia. A contrast upper gastrointestinal series should be performed if feeding is not started by week 3 postoperatively to assess the anastomosis for stricture and gastric and duodenal emptying. The dilated preatretic duodenum will likely persist for months. The decision for another surgical intervention should be carefully considered depending on the clinical and radiological data. Surgical interventions could either be in the form of reperforming the anastomosis for stricture formation or tapering duodenoplasty for a mega-duodenum that failed to properly empty [11, 43]. Other common causes of reoperation are anastomotic leak, adhesive bowel obstruction, or concomitant gastrointestinal malformation not detected in the initial operation, such as malrotation or duodenal web [40, 44]. Literature on management of anastomotic leak following duodenal atresia repair is scarce and that is likely due to the rarity of such complication. The presence of systemic signs of sepsis, significant abdominal tenderness, or abdominal wall erythema should alert the surgeon to the possibility of anastomotic leak. Significant pneumoperitoneum on plain abdominal radiographs is usually sufficient to make the diagnosis, however, contrast upper gastrointestinal series may also be required. Urgent reoperation is highly recommended with attempt to assess the cause of the anastomotic leak. Repair is done with either adding more sutures to reinforce the anastomosis or re-doing the entire anastomosis particularly if there is a major dehiscence or a problem of the duodenal orientation. Placement of a closed suction drain in area is important in such scenario. The incidence of reoperation following the initial repair is approximately 14% [40].

The late complications that are peculiar to duodenal atresia patients include mega-duodenum and blind loop syndrome. Both can present with feeding intolerance, bilious vomiting, diarrhoea, poor weight gain, recurrent abdominal pain, or bile reflux gastritis. Food or foreign body impaction can present at any age where obstruction occurs at the site of anastomosis. Upper gastrointestinal endoscopy is often helpful in assessing the duodenum and perhaps dilation if a stricture is found. Tapering duodenoplasty may be required in carefully selected groups of patients [11, 43, 45].

9. Outcomes

The overall survival of patients with duodenal atresia exceeds 90%, which is mostly due to advances in surgical techniques, neonatal care, and parenteral nutrition [11, 40]. The early mortality of less than 10% is attributed to associated anomalies or prematurity [41, 46]. Despite their high risk of associated congenital cardiac anomalies, patients with trisomy 21 have similar risks of morbidity and mortality compared with their normal counterparts [40, 41, 46]. Long-term follow-up is important due to the risk of late complications, most notably nonfunctioning mega-duodenum or gastroesophageal reflux disease, which might occur several years later [45, 47, 48].

10. Conclusion

Congenital duodenal obstruction is a relatively common gastrointestinal malformation. Prenatal ultrasonography plays an important role in anticipating this condition and should guide the early neonatal care. Surgeons must be very familiar with the anatomy of the area and the possible variations in such anomaly.

Conflict of interest

The authors declare no conflict of interest.