Duodenal atresia is one of the more common congenital intestinal anomalies.
Duodenal atresia is a condition commonly identified in new born infants as it a congenital disorder. The typical presentation is bilious vomiting within the first hour of birth. As soon as the baby takes the first few feeds, there is visible distention of the stomach and as there is duodenal atresia (complete or partial) the food regurgitates back into the stomach and the esophagus causing bilious vomiting.
During pregnancy, prenatal tests may be conducted to help confirm the defect. The mother is likely to have had polyhydramnios during pregnancy as a fetus with duodenal atresia cannot swallow the amniotic fluid.
As vomiting is a recurring complaint, the neonate will usually suffer from dehydration and electrolyte imbalance. The stomach appears scaphoid in all cases of duodenal atresia. As a rule, one must conclude bilious vomiting in an infant as a case of proximal gastrointestinal obstruction until proven otherwise. If at all an orogastric tube is introduced into the stomach, it typically will yield significant quantity of bilious fluid as 85% defects occur below the ampulla of Vater.
Investigations are many ranging from prenatal to postnatal. If there are abnormalities of the amniotic fluid quantity noticed in the mother during ante-natal checkups, complete prenatal tests and repeated scans should be done to pin point the defect.
Urinalysis should be done to assess fluid status by checking specific gravity of urine.
On prenatal diagnosis, in a case of duodenal atresia, there is excess of amniotic fluid called as polyhydramnios which can be identified by ultrasonography. With use of modern ultrasound machines, numerous affected infants can be identified in utero itself. A large study of 11 countries from Europs found that 52% infants with congenital duodenal obstruction (atresia and stenosis) were identified using ultrasound in utero .
On X-rays of the abdomen, there is a ‘double bubble sign’ visible. This is diagnostic of duodenal atresia. The first air bubble producing a dark shadow on the X-ray is the distended abdomen followed by pyloric stenosis and the presence of the second air bubble signifies the first portion of the duodenum.
Absence of gas in the remaining portion of the duodenum suggests atresia of the duodenum. Upper gastrointestinal contrast studies are unnecessary and should be avoided. Cardiac and renal ultrasound analysis might be warranted for ruling out life-threatening congenital anomalies prior to surgical repair.
Treatment consists of surgical repair consisting of duodeno-duodenostomy as there is no medication which can repair the defect. This pediatric surgery can be done laparoscopically or by the regular incision on the right upper quadrant of the abdomen .
A retrospective study which analysed the outcomes of 14 patients who underwent open incisions and 15 patients who underwent laparoscopic surgery found no anastomotic leakage in either case, the only difference being seen in quicker feeding, recovery and discharge from hospital in the laparoscopically operated group .
Prior to surgery, all the electrolytes should be investigated and deficits must be corrected. Hypokalemia is a very common complication seen due to recurrent vomiting. Stability of the electrolytes and fluid balance is a must to be achieved preoperatively. Once it is established that the infant is stable then the operation can be continued.
Advanced neonatal care has made it possible for an excellent prognosis of the infants post operation. There are very rare incidences of mortality in infants of duodenal atresia these days and most often there is an association of cardiac defects or other deformities causing death of the infant.
By itself, duodenal atresia has very good prognosis. This improvement is due to the improved neonatal care, nutritional supplement, advanced pediatric anesthesia and improved pediatric surgeries.
Patient must keep going for follow ups and regular check ups annually. There are no long term complications and the children grow normally thereafter like other children.
The exact etiology of duodenal atresia is not yet known. It is considered to be a result of malformations arising during the early development of the embryo. It may be associated with other congenital anomalies hence, suggesting that it is a developmental defect.
There are no predisposing risk factors noticed for this condition. The atresia can have many forms but the regardless of the severity of the atresia, the proximal dupdenal segment is always dilated and ends blindly while the distal duodenal segments is empty and ends blindly too .
Duodenal atresia is found to be prevalent in 1 out of every 2500 to 1 in 40,000 live births and it is not a familial condition. Around 20 to 40% of all children with duodenal atresia will have Down’s syndrome but only in about 8% of children with Down’s syndrome do we witness duodenal atresia as an associated condition .
The condition seems to be equally prevalent in neonates of both the sexes with no predilection for any particular race.
During the formation of a normal duodenum two processes take place one after another. First is endodermal proliferation and second is recanalization of the solid cord. In the process of malformation of the duodenum, there could be two possibilities leading to the atresia; either insufficient endodermal proliferation or failure to recanalize. The proliferation of the cells takes place during the first to second month of gestation.
Once the proliferation is complete, the recanalization takes place by the method of apoptosis of the cells present within the lumen of the duodenum. Thus, when apoptosis takes place there is formation of a vacuole in the lumen. Failure of vacuolization will lead to absence of a duodenal lumen.
At molecular level, cell signaling seems to be interrupted between the two embryonic layers of endoderm and mesoderm that plays a vital role in organogenesis of duodenum. There is poor pattern coordination amongst these two cell layers as well. Thus, occasionally, one may find duodenal atresia in association with an annular pancreas i.e. ring of pancreatic tissue surrounding entire duodenal circumference.
There are no guidelines for prevention of duodenal atresia
Duodenal atresia is a congenital disorder caused by developmental errors in the embryo. There also can be absence of duodenum or there can be closure of the lumen of the duodenum causing an obstruction.
This may be seen due to incomplete proliferation or incomplete vacuolization. Either of the embryogenetic processes will lead to an obstructed duodenum. There is association seen with Down’s syndrome in around 20-40% of the patients. The fetus cannot swallow the amniotic fluid and cannot absorb it in the digestive tract. Hence, there is excessive amniotic fluid in the womb.
Polyhydramnios is seen in such conditions.
The infant will pass meconium normally like other infants but there is excessive vomiting seen during the very first hour after taking a breast feed. The vomitus is typically bilious as there is obstruction and hence, the milk taken is regurgitated out. This bilious vomiting immediately after birth is the hallmark of proximal gastro-intestinal tract and should always be treated that way unless proven otherwise. There is distention of the abdomen noted.
Infant should be X-rayed as it will show the ‘double bubble sign’. The first air bubble distention is the stomach air visible on an X-ray and the next air distention is caused due to the intestinal distention beyond the obstructed duodenum.
Since it is a mechanical defect, it needs early surgical correction. Medications will not alter the state of the infant and hence surgery alone will improve the condition. Before the surgery takes place few things need to be corrected. As the infant keeps vomiting continuously there may be dehydration as well as electrolyte imbalances along with hypokalemia. Dehydration should be corrected by giving Intravenous fluids and electrolytes should be replaced.
Once the infant is stable, then the operation consisting of duodeno-duodenostomy is performed where two hollow ends of the duodenum are connected. This can be done either laparoscopicaly or by the traditional methods by taking an incision on the right upper quadrant of the abdomen. Post operation, minor complications like peptic ulcer, cholecystitis may occur.
Prognosis is good as once the defect is corrected the infants live normally with no long term complications. There is no risk for operation if only duodenal atresia is present in the infant bu,t if there are any associated cardiac complications then the risk increases. Recently, prenatal tests help to rule out the defect and hence pediatric surgery can be planned in advance.