The erect chest x-ray shows a crescent of air under the left hemi-diaphragm, suggestive of pneumoperitoneum.
There is also a tooth-like calcific density in the left adnexal region. This is likely to represent a left ovarian dermoid.
This patient went on to have a CT scan of the abdomen, which confirmed pneumoperitoneum arising from a perforated peptic ulcer. The CT also showed a 6cm left ovarian dermoid cyst.