Duodenal obstruction is a blockage in the duodenum, the first segment of the small intestine. This condition prevents the normal passage of digested food and fluids from the stomach into the digestive tract. It requires prompt medical evaluation and intervention to prevent complications.
Understanding Duodenal Obstruction
The duodenum is the initial section of the small intestine, directly connected to the stomach’s outlet, the pylorus. Its primary function involves receiving partially digested food, called chyme, from the stomach and mixing it with digestive enzymes from the pancreas and bile from the liver. This mixing initiates further breakdown of nutrients for absorption.
When an obstruction occurs in the duodenum, the flow of chyme is impeded, leading to a buildup of contents upstream from the blockage. This accumulation can cause distension and increased pressure within the stomach and duodenum. Obstructions can be either complete, meaning no material can pass through, or partial, allowing some limited passage of contents.
Duodenal obstructions are categorized by their origin, either as congenital or acquired. Congenital obstructions are present at birth, resulting from developmental anomalies during fetal growth. Acquired obstructions develop later in life due to various factors, including disease, injury, or other medical conditions.
Common Causes
Duodenal obstructions can arise from a range of factors, broadly categorized into those present at birth and those that develop later in life. Congenital causes stem from abnormalities during fetal development, impacting the duodenum’s formation. These include duodenal atresia, where a segment of the duodenum is completely closed off or absent. Another congenital cause is an annular pancreas, where pancreatic tissue encircles and constricts the duodenum. Intestinal malrotation, where fibrous bands (Ladd’s bands) cross and compress the duodenum, can also lead to obstruction.
Acquired causes of duodenal obstruction develop after birth due to various medical conditions:
Tumors, both benign and malignant, originating in or near the duodenum, can compress or infiltrate the duodenal wall.
Abdominal adhesions, bands of scar tissue forming after surgery or inflammation, can also constrict the duodenum.
Peptic strictures, resulting from severe or chronic inflammation and scarring due to peptic ulcers.
Gallstone ileus, a rare condition where a large gallstone becomes lodged in the duodenum.
Inflammation from conditions such as acute or chronic pancreatitis, or inflammatory bowel diseases like Crohn’s disease.
Recognizing the Symptoms
Symptoms of duodenal obstruction vary based on the patient’s age and the degree of blockage.
In Newborns
Common signs include recurrent vomiting, often bilious (green or yellow-green due to bile content), typically occurring within the first 24 to 48 hours of life. Abdominal distension may also be present due to the accumulation of fluid and gas.
In Older Children and Adults
Nausea and persistent vomiting, which can be bilious or contain undigested food, are common. Abdominal pain is a frequent symptom, usually described as cramping or intermittent, and tends to worsen after eating. The pain is often localized to the upper abdomen. Patients may also experience significant abdominal distension, as gas and fluid build up above the obstruction. A diminished ability to pass gas or stool frequently accompanies the blockage. These symptoms can progress in severity as the obstruction becomes more complete or prolonged.
Diagnosis and Treatment
Diagnosis
Diagnosis typically begins with a thorough physical examination, where a healthcare provider assesses for signs like abdominal distension, tenderness, or visible peristaltic waves. Imaging studies are then performed to confirm the blockage and identify its location and cause. Common diagnostic methods include:
Plain abdominal X-rays: May reveal a “double bubble” sign in infants, indicating air trapped in the stomach and the first part of the duodenum.
Computed tomography (CT) scan: Provides detailed cross-sectional images, helping to visualize the obstruction, its extent, and potential causes.
Upper gastrointestinal (GI) series: Involves swallowing a barium-based contrast material for real-time visualization of its passage through the duodenum on X-ray images. This can highlight areas of narrowing or complete blockage.
Endoscopy: Involving the insertion of a flexible tube with a camera, may be used to visualize the duodenal lining and obtain tissue samples if a mass or stricture is suspected.
Treatment
Treatment for duodenal obstruction generally involves surgical intervention to relieve the blockage. Before surgery, supportive care measures are initiated, including intravenous fluids to correct dehydration and electrolyte imbalances, and the insertion of a nasogastric tube to decompress the stomach and remove accumulated fluids and air.
The specific surgical procedure depends on the cause. For example, in duodenal atresia, the surgeon connects the two ends of the duodenum to restore continuity. If the obstruction is caused by an annular pancreas, a bypass procedure like a duodenoduodenostomy or duodenojejunostomy is often performed. For obstructions due to tumors or strictures, surgical removal of the affected segment or creation of a bypass may be necessary. In some cases, endoscopic treatments like balloon dilation or stent placement might be considered to open the narrowed passage.
Potential Complications
If duodenal obstruction is left untreated, complications can arise:
Dehydration and Electrolyte Imbalances: Persistent vomiting leads to substantial fluid loss, resulting in dehydration and imbalances in the body’s electrolytes, such as sodium and potassium. These imbalances can affect heart function and other bodily processes.
Malnutrition: Chronic obstruction can also lead to malnutrition, as the body is unable to absorb adequate nutrients.
Aspiration Pneumonia: The continuous vomiting also poses a risk of aspiration pneumonia, where stomach contents are accidentally inhaled into the lungs, leading to infection and inflammation.
Bowel Ischemia or Necrosis: Compromised blood supply to the affected segment of the duodenum can lead to bowel ischemia (reduced blood flow) or necrosis (tissue death).
Perforation and Peritonitis: If the pressure within the obstructed segment becomes too high, it can lead to perforation, a rupture in the duodenal wall. This perforation allows digestive contents to leak into the abdominal cavity, causing peritonitis, a life-threatening infection and inflammation of the abdominal lining.