Chapter 40: Abdominal X-Ray Interpretation

Abdominal X-Ray Interpretation outlines the standard views obtained, including the flat plate or anteroposterior (AP) view—often referred to as a KUB (kidneys, ureter, bladder)—as well as erect and left lateral decubitus views, which are critical for detecting free air indicative of perforation or assessing air-fluid levels in bowel obstructions. The text details a systematic approach to reading these images, emphasizing the need to verify patient identity, assess image quality (exposure), and sequentially evaluate anatomical structures including the liver, spleen, psoas muscles, and renal outlines. Significant attention is given to distinguishing normal gas patterns from pathologies; for instance, the summary explains how to differentiate between mechanical bowel obstructions (characterized by specific dilation thresholds, such as the small bowel being greater than 3 cm or the colon greater than 6 cm) and paralytic ileus. It also describes the radiographic appearance of abnormal calcifications in the aorta or organs and the "crescent sign" of pneumoperitoneum under the diaphragm. Furthermore, the chapter contrasts plain film radiography with other diagnostic modalities like barium studies (upper and lower GI series), endoscopy, colonoscopy, computed tomography (CT), and ultrasonography, explaining when these advanced techniques are superior for diagnosing issues like diverticulitis, appendicitis, or masses. Finally, it addresses evidence-based practice regarding the high radiation exposure of abdominal x-rays and their limitations in undifferentiated abdominal pain, suggesting careful clinical judgment in their application.