Q: 78 year old male presented with severe abdominal pain. Patient is taking huge amount of over the counter NSAIDs and you suspect perforated peptic ulcer. As an initial workup you ordered upright KUB. Looking at portable screen of technician you didn't see any free air. What should be your next step?


Answer: Take a left lateral decubitus film.

Plain x-rays of the abdomen with the patient in the upright position have been used in diagnosing perforated ulcer. However, in 30% to 50% of patients, the x-ray may be negative for free air, particularly in the elderly. A left lateral decubitus film has been shown to be most sensitive in detecting pneumoperitoneum. Placing the patient in the upright or left lateral decubitus position for 10 minutes before taking the x-ray may help detect the condition. Similarly, use of water-soluble contrast medium with an upper gastrointestinal tract series or computed tomography scan may increase the diagnostic yield.