A stomach X-ray, more accurately termed an abdominal X-ray or plain film, is a rapid, non-invasive imaging procedure that uses a small dose of ionizing radiation. This test generates an image of the internal abdominal structures based on their density. Dense structures, such as bone and swallowed metal, absorb the radiation and appear white. Air-filled spaces, like the stomach and intestines, appear black, while soft tissues show up in various shades of gray.
Immediate Findings on a Standard X-ray
A standard, non-contrast abdominal X-ray, sometimes called a KUB, is often the first tool used in emergency situations. One urgent finding is the presence of free air, or pneumoperitoneum, which suggests a perforation or tear in the stomach or intestine wall. This free air collects beneath the diaphragm and appears as a distinct black crescent shape, indicating a medical emergency.
The X-ray is also effective at evaluating the bowel gas pattern, which is the distribution of air throughout the digestive tract. An abnormal pattern, such as overly dilated loops of small bowel with multiple air-fluid levels, suggests an obstruction or blockage. Conversely, an overall lack of movement, known as an ileus, presents with gas distributed throughout the small and large bowel without the signs of a mechanical blockage.
Foreign bodies are also readily detectable if they are radiodense, meaning they are made of material like metal, glass, or bone. The X-ray quickly confirms the presence and location of a swallowed object, which is useful in pediatric cases or when ingestion is suspected. The film can also reveal abnormal calcium deposits, known as calcifications, which appear bright white. These calcifications can include gallstones, kidney stones, or calcified masses related to conditions like chronic pancreatitis.
Detailed Diagnosis Using Contrast Studies
To move beyond basic structural and gas patterns, a contrast study, such as an Upper Gastrointestinal (GI) series or barium swallow, is performed. This procedure involves the patient drinking a liquid containing barium sulfate, which is opaque to X-rays and coats the inner lining of the esophagus, stomach, and duodenum. Using fluoroscopy, the radiologist observes the barium moving through the upper digestive tract in real-time.
This dynamic visualization provides detailed information about the function and contour of the stomach wall, which is impossible to see on a plain X-ray. The barium coating allows for the detection of mucosal abnormalities, such as a peptic ulcer crater or the irregular lining characteristic of gastritis. Structural problems like strictures, which are abnormal narrowings, or filling defects caused by masses and polyps, are clearly outlined by the contrast agent.
Real-time fluoroscopy is also used for diagnosing functional disorders by observing the motion of the stomach and the muscular valves, or sphincters. For example, the test can reveal gastroesophageal reflux disease (GERD) by showing the backward flow of barium from the stomach into the esophagus. It also helps diagnose a hiatal hernia, where a portion of the stomach pushes up through the diaphragm and into the chest cavity.
When an X-ray is Not Enough
Despite the added detail provided by contrast agents, X-rays have inherent limitations, particularly regarding soft tissue differentiation. Both plain and contrast X-rays are poor at distinguishing between different types of soft tissue, such as a benign tumor, a malignancy, or localized inflammation. While they can show an irregularity or filling defect, they lack the specificity to characterize the tissue itself.
For a definitive diagnosis, especially to evaluate the depth of a mass or the extent of disease, follow-up procedures are necessary. Computed Tomography (CT) scans use X-rays from multiple angles to create detailed cross-sectional images, which are superior for imaging solid organs and soft tissue structures. Endoscopy is also a frequent next step, allowing a physician to directly visualize the stomach lining and take a tissue sample or biopsy for laboratory analysis.