Intestinal atresia is a congenital condition where a portion of the intestine is either completely blocked or significantly narrowed at birth. This malformation prevents the normal passage of digested food and waste through the digestive tract. Advancements in medical care have made intestinal atresia a highly treatable condition, with most affected infants achieving positive outcomes.
What is Intestinal Atresia?
Intestinal atresia is a malformation where a segment of the intestine is either entirely closed off (atresia) or narrowed (stenosis). This can occur in either the small or large intestine. The severity ranges from a partial obstruction to a complete absence of a portion of the intestine.
The condition is classified by its location within the digestive tract. Duodenal atresia affects the duodenum, the first part of the small intestine immediately after the stomach. Jejunal and ileal atresia involve the jejunum (middle part) and ileum (lower part) of the small intestine, respectively. These are further categorized into types based on the nature of the blockage and the gap between intestinal segments: Type I involves a web-like membrane, Type II features blind ends connected by a fibrous cord, Type IIIa has blind ends separated by a gap in the mesentery, Type IIIb (apple peel atresia) involves a large mesenteric gap and a foreshortened, coiled distal bowel, and Type IV indicates multiple atretic segments. Colonic atresia, a blockage in the large intestine, is less common, accounting for less than 15% of all intestinal atresias.
Causes and Risk Factors
For most cases of intestinal atresia, the specific cause remains unknown, and it is generally considered a sporadic event rather than an inherited condition. The most widely accepted theory for jejunal and ileal atresia involves a “vascular accident” during fetal development. This means that the blood supply to a segment of the fetal intestine is interrupted, leading to its improper development or complete obliteration.
Duodenal atresia, however, often has different underlying factors. It is frequently associated with other genetic conditions, most notably Down syndrome (Trisomy 21), which is present in 20% to 30% of infants with duodenal atresia. Other congenital anomalies, such as heart defects or kidney problems, can also be present.
Recognizing the Signs and Diagnosis
Signs of intestinal atresia can be detected before birth during routine prenatal ultrasounds. One common indicator is polyhydramnios, an excessive accumulation of amniotic fluid around the fetus, occurring because the fetus cannot properly swallow and absorb it due to the intestinal blockage. For duodenal atresia, prenatal ultrasound may reveal a “double bubble sign,” signifying a dilated stomach and the first part of the duodenum.
After birth, key symptoms emerge shortly after delivery. These include bile-stained vomiting, which is green or yellow-green, indicating that digestive fluids cannot pass beyond the obstruction. Abdominal distension is also a common sign. The infant may also fail to pass meconium within the first 24 to 48 hours of life.
Diagnostic confirmation usually involves a physical examination and imaging studies. Abdominal X-rays often show dilated loops of intestine or the “double bubble sign.” Contrast studies, such as a barium enema, may be used to pinpoint the exact location and type of blockage. These steps help differentiate intestinal atresia from other conditions and guide treatment.
Treatment Approaches
Intestinal atresia requires prompt surgical intervention. Before surgery, medical teams focus on stabilizing the infant’s condition. This involves administering intravenous (IV) fluids to prevent dehydration and inserting a nasogastric tube. The nasogastric tube helps to decompress the stomach and remove excess intestinal contents and gas, which reduces vomiting and abdominal swelling.
The primary goal of the surgical procedure is to remove the blocked or narrowed segment of the intestine and then reconnect the healthy ends. This reconnection is called an anastomosis. The specific surgical technique varies depending on the type and location of the atresia.
In some cases, if the intestinal ends cannot be immediately reconnected due to inflammation or significant size difference, a temporary ostomy may be created. This involves bringing a part of the intestine to the surface of the abdomen to allow waste to exit into a bag, giving the bowel time to heal before a second surgery to reconnect the ends. The surgery is generally performed within the first few days of life.
Following surgery, infants enter a recovery period that often involves total parenteral nutrition (TPN). TPN provides all necessary nutrients intravenously while the bowel heals and recovers its function. Oral feedings are reintroduced as the digestive system begins to work properly. Close monitoring is maintained for potential complications, such as anastomotic leaks or the formation of scar tissue (adhesions).
Prognosis and Long-Term Care
With timely diagnosis and appropriate surgical intervention, the prognosis for infants with intestinal atresia is generally excellent. For isolated atresia, meaning the condition occurs without other major birth defects, survival rates are very high. Most children who undergo successful repair lead normal, healthy lives.
However, long-term considerations may arise if a significant portion of the intestine is removed during surgery. This can lead to a condition known as short bowel syndrome, where the remaining intestine may not be long enough to absorb sufficient nutrients. Infants with short bowel syndrome may require ongoing nutritional support, which could include specialized diets or continued intravenous nutrition for a longer period.
Follow-up care with pediatric specialists, such as gastroenterologists, is often recommended to monitor the child’s growth, nutritional status, and bowel function. While some children may experience issues like malabsorption or require dietary adjustments, many intestinal rehabilitation programs help improve outcomes for those with short bowel syndrome, enabling them to eventually discontinue parenteral nutrition.