Pyloric stenosis (PS) is generally known for its occurrence in newborns, where the muscular valve between the stomach and the small intestine, called the pylorus, becomes abnormally thickened. This thickening creates a blockage that prevents food from passing into the duodenum. While overwhelmingly associated with infancy, a form of pyloric stenosis can rarely manifest in adults. Adult-onset pyloric stenosis is an uncommon diagnosis requiring detailed understanding of its causes and presentation.
What is Pyloric Stenosis?
Pyloric stenosis is fundamentally an anatomical problem resulting in a mechanical obstruction known as gastric outlet obstruction (GOO). The pylorus acts as a gatekeeper, regulating the flow of partially digested food from the stomach into the upper small intestine. When the muscle fibers of the pylorus thicken, the narrow opening, or lumen, becomes constricted. This physical narrowing prevents the stomach contents from emptying normally, causing a backup of food and fluid.
The classic form seen in infants, Infantile Hypertrophic Pyloric Stenosis, is characterized by significant muscle hypertrophy, meaning the muscle cells themselves enlarge. Regardless of the age of onset, the physical mechanism remains the same: the stomach cannot effectively push its contents past the narrowed channel, leading to symptoms related to digestive tract dysfunction.
Causes of Adult Pyloric Stenosis
Adult Pyloric Stenosis (APS) is categorized into two distinct types based on its origin: primary and secondary. The secondary type is by far the more common cause in adults presenting with obstruction symptoms. This secondary form develops as a consequence of an underlying disease process within the gastrointestinal tract.
The most frequent cause of secondary APS is chronic Peptic Ulcer Disease (PUD), particularly ulcers located near the pylorus or in the duodenum. As these ulcers heal repeatedly over time, the resulting scar tissue, or fibrosis, contracts and causes a permanent narrowing of the pyloric channel. This fibrous tissue physically constricts the passage, even in the absence of active inflammation.
Malignancy represents another serious cause of secondary APS, including tumors of the stomach (gastric cancer) or the head of the pancreas. These cancers can either grow directly into the pylorus, causing intrinsic blockage, or compress it from the outside. Chronic inflammatory conditions, such as Crohn’s disease or eosinophilic gastroenteritis, can also lead to secondary stenosis. Inflammation and subsequent scarring in the distal stomach or duodenum creates strictures that progressively tighten the pyloric opening.
The much rarer form is Adult Idiopathic Hypertrophic Pyloric Stenosis (AIHPS), which mirrors the infantile condition. This primary form involves the benign thickening (hypertrophy and hyperplasia) of the pyloric muscle without an identifiable underlying cause. Researchers believe AIHPS represents a latent form present since birth but not becoming symptomatic until adulthood, typically in middle age. The muscle thickening in AIHPS is often more pronounced than the fibrosis seen in secondary cases.
Recognizing Symptoms in Adults
The symptoms of adult pyloric stenosis are those of chronic gastric outlet obstruction, which can be vague in early stages. Nausea and vomiting are the cardinal signs, often occurring hours after a meal when the stomach attempts to empty its contents. The vomitus is typically non-bilious (meaning it does not contain bile) and frequently contains undigested food consumed many hours earlier.
Patients often report early satiety, feeling full quickly after starting a meal due to the stomach’s inability to empty efficiently. This persistent obstruction and the resulting chronic vomiting lead to significant complications. Unexplained weight loss is a frequent concern, especially when the cause is malignant, due to poor nutrient absorption and reduced oral intake.
Chronic vomiting causes a significant loss of stomach acid and water, which results in dehydration and electrolyte imbalances. These imbalances include hypokalemia (low potassium) and a hypochloremic metabolic alkalosis, a specific chemical shift in the body’s acid-base balance. Over time, the stomach can become dilated and distended as it attempts to accommodate the accumulating food and fluid.
Diagnosis and Management Options
The diagnostic process aims to confirm pyloric stenosis and determine the underlying cause. Initial laboratory tests assess the patient’s hydration status and correct severe electrolyte abnormalities resulting from chronic vomiting. Imaging studies, such as a computed tomography (CT) scan or a barium upper gastrointestinal series, can reveal a dilated stomach and show the narrowed pyloric channel.
Upper endoscopy (EGD) is the most definitive diagnostic tool, allowing direct visualization of the pylorus. The endoscopist assesses the degree of narrowing and looks for signs like a fixed, rigid pylorus, sometimes described as the “Cervix sign” in primary hypertrophic cases. Crucially, endoscopy allows for biopsies to be taken from the narrowed area to rule out malignancy, a necessary step given the high rate of secondary causes.
Management is tailored specifically to the cause of the obstruction. For secondary stenosis caused by Peptic Ulcer Disease, initial treatment involves acid-suppressing medications like proton pump inhibitors to reduce inflammation, sometimes combined with endoscopic balloon dilation. If the obstruction is caused by cancer, treatment focuses on chemotherapy, surgical resection of the tumor, or the placement of an endoscopic stent to bypass the blockage.
For primary hypertrophic pyloric stenosis, or secondary cases unresponsive to medical therapy, surgical intervention is typically required. Surgical options include a pyloroplasty (such as the Heineke-Mikulicz procedure), which widens the pyloric channel, or a pyloromyotomy, which involves surgically cutting the thickened muscle to relieve the constriction. In complex or malignant cases, a partial gastrectomy may be necessary to remove the diseased section entirely.