A duodenal obstruction occurs when there is a partial or complete blockage in the duodenum, the first segment of the small intestine, which connects the stomach to the rest of the small intestine. The duodenum receives partially digested food (chyme) from the stomach and mixes it with bile and pancreatic digestive juices for nutrient absorption. When an obstruction occurs, the normal passage of contents is hindered, causing a backup of food and secretions that interferes with digestion, nutrition, and fluid balance.
Types and Underlying Causes
Duodenal obstructions are categorized as either congenital (present at birth) or acquired (developing later in life). Congenital obstructions result from errors in fetal development, typically involving the failure of the duodenal channel to properly form. During normal development, the duodenal lumen briefly solidifies before re-establishing the open passage, and a failure in this step leads to intrinsic blockages.
The most frequent intrinsic congenital cause is duodenal atresia, a complete blockage often caused by a membrane or a gap between segments. Duodenal stenosis is a similar condition involving a severe narrowing rather than a complete closure. An annular pancreas is another congenital cause, where pancreatic tissue wraps completely around the duodenum, compressing it externally.
Acquired obstructions affect older children and adults, stemming from various factors that create physical blockage or external pressure.
Acquired Causes
Tumors, whether benign or malignant, can grow within the duodenal wall or in surrounding organs like the pancreas, causing compression. Peptic strictures are a common acquired cause, resulting from chronic inflammation and scarring due to severe peptic ulcer disease, leading to a fixed narrowing of the lumen.
Another mechanical cause is Superior Mesenteric Artery (SMA) Syndrome, where the duodenum is compressed between the aorta and the superior mesenteric artery. This external compression often occurs in individuals with rapid weight loss, as the protective fat cushion diminishes. Inflammatory conditions like Crohn’s disease can also cause acquired stenosis through chronic inflammation and subsequent fibrosis.
Recognizing the Signs
The clinical presentation varies depending on the patient’s age and whether the blockage is complete or partial.
Neonates and Infants
In newborns and infants, obstruction presents within the first few days of life. The hallmark symptom is bilious vomiting, meaning the vomit is stained green because the blockage is typically located after the opening where bile enters the duodenum.
Other symptoms in neonates include abdominal distension, usually limited to the upper abdomen, and a failure to pass meconium, which is the infant’s first stool. This acute presentation requires immediate medical attention.
Older Children and Adults
In older children and adults, signs are often more chronic and vague, especially with a partial blockage (stenosis). Patients commonly experience intermittent nausea, vomiting, abdominal pain, and a feeling of fullness after eating only a small amount of food, known as early satiety. Vomiting may be non-bilious if the obstruction is located before the entry of the bile duct. Over time, these symptoms can lead to significant weight loss and malnutrition.
Diagnostic Procedures
Evaluation begins with a physical examination and laboratory work to assess for dehydration and electrolyte imbalances caused by persistent vomiting. Imaging studies are the primary tool used to confirm the presence and location of the blockage. Plain abdominal X-rays are often the first step, especially in infants.
In neonates with a complete obstruction, X-rays frequently show the classic “double bubble sign,” which is pathognomonic for the condition. The two bubbles represent the air-filled, dilated stomach and the dilated proximal duodenum, with little air visible elsewhere in the intestine. For partial obstructions or unclear diagnoses, a contrast study, such as an upper gastrointestinal series, may be performed.
During a contrast study, a liquid that shows up on X-ray is swallowed or administered through a tube, allowing visualization of the digestive tract. This helps differentiate between a complete blockage and a partial narrowing. In adults, computed tomography (CT) scans and ultrasound are used to visualize external causes of obstruction, such as tumors, pancreatic inflammation, or SMA compression.
Management and Treatment Options
Treatment begins with immediate patient stabilization. A nasogastric (NG) tube is inserted to continuously suction accumulated fluid and air (decompression), relieving pressure and preventing aspiration.
Intravenous (IV) fluids are administered to correct dehydration and restore the balance of essential electrolytes lost through vomiting. Nutritional support, sometimes involving total parenteral nutrition (TPN) delivered intravenously, may be necessary to improve the patient’s condition before surgery. This stabilization period is important for reducing the risk of complications during the definitive procedure.
Surgical correction is the definitive treatment required to resolve nearly all duodenal obstructions. The specific operation depends on the cause. For congenital obstructions like duodenal atresia, a procedure called duodenoduodenostomy is performed, creating a new connection to bypass the blocked segment.
For acquired obstruction due to tumors or scarring, surgery may involve resecting the blocked section or performing a surgical bypass, such as a gastrojejunostomy, which connects the stomach directly to the jejunum, bypassing the duodenum entirely. Post-operatively, patients require close monitoring and continued nutritional support, such as TPN or specialized feeding tubes, to ensure adequate healing and recovery of normal intestinal function.