Pneumoperitoneum - the importance of projection
This 35 year-old patient presented to A and E with upper abdominal pain of short duration.
Initial films discussed with duty radiologist by the surgeon as concerns over a perforation but 'normal films'
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At presentation a SUPINE chest x-ray and abdominal radiograph were performed for the clinical indication of abdominal pain.
SUPINE CXR: No free subdiaphragmatic gas
ABDOMINAL FILM: Unusual area of lucency overlying the right upper quadrant, which appears extra-luminal in nature
REPEAT CXR IN THE ERECT POSITION (20 MINUTES LATER): Large volume pneumoperitoneum.
Sometimes the best lessons in life are the simple ones.
The learning points from this case are:
1. Always interrogate the film characteristics - the projection is important to find the pathology
2. Patients are always served better when clinicoradiological discussion takes place
3. Even with advanced imaging modalities plain radiographs are still important and interesting
Pneumoperitoneum is more easily identified on the erect CXR, than the AXR, but a number of signs of free gas on AXR have been described.
These include: the falciform ligament sign, triangles of gas, the football sign, inverted V sign and 'right upper quadrant gas sign'.
- Levine, MS Scheiner,JD Rubesin,SE Laufer, I, Herlinger, H. Diagnosis of pneumoperitoneum on supine abdominal radiographs. AJR, 1991:156 (4);731-735
- Rigler,LG. Spontaneous Pneumoperitoneum: A Roentgenologic Sign Found in the Supine Position. Radiology, 1941:37:604-607.