The Abdominal Plain Film- Appendicitis

Introduction

Identifying an appendicolith can assist greatly in diagnosing appendicitis in patients presenting with acute abdominal pain. This page looks at the appendicolith and other signs of appendicitis.

Epidemiology

• Appendicitis is the most common infective condition that presents as an acute abdomen

Aetiology

• Requires the occlusion of the appendiceal lumen by particulate material- material could be endogenously produced or foreign

• Material could be blocking the lumen or a focus or nidus upon which faeces adhere and calcium salts are laid down

Clinical Pathway

An abdominal plain film is not considered an appropriate examination in patients with suspected appendiciis in many centres.

Plain Film Signs of Appendicitis

Sign	Comment
Appendicolith	Also known as coproliths, fecaliths and stercoliths Appendicoliths are common Can appear in various locations with variation in location of the appendix Not all appendix stones are calcified
Gas in Appendix	This is not necessarily a sign of appendicitis- can be seen in the normal appendix
Abscess RIF mass	There can be a general increase in opacity in the right lower quadrant associated with an appendiceal abscess Can also be seen as bubbles of gas in the abscess
Caecal Ileus	Seen as dilated caecum
Flank Sign	Separation of the bowel from the right flank stripe by the lateral accumulation of pus and ascites
SBO	Reflex ileus
Scoliosis	Scoliosis of lumbar spine

Case 1

•21 year old male with months of RIF pain •Increased white cell count •Appendicolith (bottom arrow) •A few prominent loops of small bowel. •suggestion of a dilated caecum (top arrow) Appendicolith (5mm) and thick-walled appendix (12mm diameter) on CT below (white arrow)

Case 2

•42 year old male with right sided abdominal pain •layered appendicolith (arrowed) •Erect AXR •Appendicolith (white arrow) •Fluid filled appendix with air/fluid level (black arrow) ? loss of clarity of right psoas muscle

Case 3

42 year old female with abdominal pain Supine AXR day 1 •loss of right psoas shadow •Appendicolith (arrow 1) •Distortion/medial displacement of caecal shadow •Extraluminal gas/faeces/pus between caecum and right flank stripe- abscess (arrow 2) •Dilated transverse colon (arrow 3) Supine AXR day 2 Small bowel distention (obstruction/ileus) •Featureless, particularly on RHS •Appendicolith (black arrow) •Separation of the bowel from the right flank stripe by the lateral accumulation of pus and ascites dilated loop of jejunum

Case 4

The arrowed structure could be mistaken for an appendicolith. It was revealed on CT to be a bony lesion in the pelvis. Not everything that looks like an appendicolith is an appendicolith!

Summary

An abdominal plain film diagnosis of appendicitis is not always possible. A significant proportion of appendicitis patients will have no plain film signs. However, when the signs of appendicitis are evident, a timely diagnosis will potentially improve patient outcomes. Importantly, the benefits of an abdominal plain film in patients with suspected appendicitis are questionable.

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