Clean vs. Dirty Shadowing
Greetings Scan Squad!
This week I want to talk about another common question: clean versus dirty shadowing.
Shadowing can be called ‘clean’ when there is complete dropout with sharp edges to the shadow. This occurs due to complete absorption of the ultrasound waves. It is typically caused by stones (any location), bone (rib, pelvis etc.) and foreign bodies.
On the other hand, ‘dirty’ shadowing has a hazy appearance. It is due to complete reflection of the ultrasound waves. It is typically caused by gas or air.
The most important thing to remember is that there is overlap between the two types of shadowing. Just because there is a dirty shadow, does not mean you can rule out a foreign body!
Happy scanning!
A clean, strong shadow (arrow) produced by a foreign body in the jejunum. You can see a dilated (measuring 1.43cm in height) segment of jejunum to the right of the foreign body. It contains echogenic liquid ingesta within the lumen.
Dirty shadowing at the ileo-colic junction (ICJ). Shadowing is present in both the colon (arrow on the left) and the ileum (arrow on the right). The shadowing is caused by gas (remember the hyperechoic line at the mucosal interface) in the lumen.
About Belinda
Dr. Belinda Carey is a veterinarian, educator and founder of eVet Academy, with a passion for making veterinary ultrasound practical and accessible. After graduating with first-class honours and earning her MANZCVS in Small Animal Internal Medicine, Belinda spent years providing mobile ultrasound services to general practice clinics, where she recognised a widespread need for practical, step-by-step ultrasound training.
Combining her veterinary expertise with her teaching background, she created eVet Academy to help small animal vets build confidence and improve their scanning skills through clear, clinically relevant education designed for everyday practice.
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