Ultrasonography of appendicitis

Author: Mikael Häggström

Contents

Choice of initial exam

In suspected appendicitis:

• Ultrasonography is the first choice of exam. In children, it gives a proper diagnosis in the vast majority even in obese children. In adults, it is often inconclusive, but is still recommended as a first imaging choice when symptoms indicate the condition. If inconclusive, further evaluation can be done by reassessment by the clinician, as well as complementary imaging with MRI or CT.
• CT of appendicitis is the preferable initial method in the elderly, who are less likely to develop adverse effects from the radiation dose. It is also indicated as initial exam in adults with more non-specific acute abdominal symptoms.

Findings

Ultrasound showing appendicitis and an appendicolith

Ultrasound of a normal appendix for comparison

A normal appendix without and with compression. Absence of comprehensibility indicates appendicitis.

Findings indicating appendicitis:

• Absence of compressibility
• Dilatation >6 mm in outer diameter
• Appendicolith
• Distinct wall layers
• Hyperechoic and prominent periappendiceal and pericecal fat
• Periappendiceal fluid
• Target sign
• Periappendiceal lymphadenopathy

Report

• Location of the appendix is important when surgery may be needed. At least when atypically located, the description should include both area in relation to surface landmarks, as well as relation to internal structures, particularly the cecum.
• Findings as per above, or negation of signs of appendicitis.
• Presence/Absence of ascites or any visible lymphadenopathy, also helpful in differential diagnosis