What are some of the causes of pneumoperitoneum (think about how you would answer this question in an oral exam; in other words make sure your answer is structured).
There are numerous causes of a pneumoperitoneum, with most cases being due to perforated hollow viscus (e.g. perforated peptic ulcer, perforated diverticulum, ischaemic / necrotic bowel, malignancy). Iatrogenic pneumoperitoneum is also common (e.g. surgery, ascites drainage, peritoneal dialysis, perforated endoscopy). Air can also pass into the peritoneum from the chest (e.g. ventilation, pneumomediastium, pneumothorax) or rarely the vagina (e.g. orogenital insufflation).
What is the likely cause of pneumoperitoneum in this patient?
Perforated duodenal ulcer, seen at the junction for the first and second part of the duodenum (D1/2).
What is the most common cause of duodenal ulcers?
Chronic infection with Helicobacter pylori.
If ulcers are numerous or located in the second or third part of the duodenum, what uncommon cause should be considered?
Zollinger-Ellison syndrome
What is Zollinger-Ellison syndrome?
Hypersecretion of stomach acid due to a gastrin secreting tumour.
Large amounts of free intraperitoneal gas are seen, most easily appreciated under the right diaphragm. Small bowel pattern is unremarkable. Two calcified masses are seen projecting over the right sacroiliac joint on the right. No pneumobilia.