Question:easy
Gas under the diaphragm is most commonly seen in which of the following conditions?
Gas under the diaphragm is most commonly seen in which of the following conditions?
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Gas under the diaphragm on an erect X-ray signifies free air in the peritoneal cavity -- think of the most common cause of pneumoperitoneum.
Updated On: Jun 23, 2026
- Viscus perforation
- Liver abscess
- Spontaneous rupture of oesophagus
- Empyema Thorax
Show Solution
The Correct Option is A
Solution and Explanation
Pneumoperitoneum -- gas under the diaphragm:
Free intraperitoneal gas rises to the highest point in the abdominal cavity and collects beneath the diaphragm. On an erect chest X-ray or erect abdominal X-ray, this appears as a crescent of radiolucency between the liver (right side) and the diaphragm, and/or between the stomach and the left diaphragm.
Causes of pneumoperitoneum (in order of frequency):
1. Hollow viscus perforation (MC) -- perforated peptic ulcer, perforated appendix, perforated carcinoma, perforated diverticulitis
2. Post-laparoscopy / post-laparotomy (iatrogenic)
3. Gas-forming intra-abdominal infections (rare, ~10% of cases)
4. Pneumatosis intestinalis (very rare)
Why not the other options:
- Liver abscess: Gas may be seen within the abscess cavity, NOT as free subdiaphragmatic gas
- Boerhaave syndrome: Produces pneumomediastinum, NOT pneumoperitoneum
- Empyema thorax: Confined to the pleural space -- no intraperitoneal gas
\[\boxed{\text{Answer: A -- Viscus perforation}}\]
Free intraperitoneal gas rises to the highest point in the abdominal cavity and collects beneath the diaphragm. On an erect chest X-ray or erect abdominal X-ray, this appears as a crescent of radiolucency between the liver (right side) and the diaphragm, and/or between the stomach and the left diaphragm.
Causes of pneumoperitoneum (in order of frequency):
1. Hollow viscus perforation (MC) -- perforated peptic ulcer, perforated appendix, perforated carcinoma, perforated diverticulitis
2. Post-laparoscopy / post-laparotomy (iatrogenic)
3. Gas-forming intra-abdominal infections (rare, ~10% of cases)
4. Pneumatosis intestinalis (very rare)
Why not the other options:
- Liver abscess: Gas may be seen within the abscess cavity, NOT as free subdiaphragmatic gas
- Boerhaave syndrome: Produces pneumomediastinum, NOT pneumoperitoneum
- Empyema thorax: Confined to the pleural space -- no intraperitoneal gas
\[\boxed{\text{Answer: A -- Viscus perforation}}\]
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