Plain radiological signs

The radiological signs in acute appendicitis are very variable and non-specific. Plain films can help to eliminate components of the differential diagnosis such as air under the diaphragm for perforated peptic ulcers. Erect and supine films are taken. There is no role for contrast studies.

Reported signs include:

• fluid levels localised to the caecum and the right terminal ileum indicating inflammation in the right lower quadrant of the abdomen
• localised ileus, with gas in the caecum, ascending colon or terminal ileum
• increased soft tissue density in the right lower quadrant
• blurring of the right flank stripe produced by the fat interposed between peritoneum and transversus abdominis
• a faecolith in the right iliac fossa
  • the majority are radio-opaque
  • occur in about 10% of those with appendicitis
  • often mistaken for ureteric calculus or gallstones
• a gas-filled appendix
• free intraperitoneal gas