Psoas sign (abdominal x-ray)

Last revised by Dr Jeremy Jones on 10 Jul 2021

The psoas sign is a classic non-specific finding on the abdominal radiograph, potentially representing retroperitoneal pathology.

Normally on an abdominal radiograph, the lateral margins of both the psoas muscles are clearly visible due to adjacent fat. When the lateral edge of one, or both, psoas muscle(s) is no longer clearly demarcated, this is a positive psoas sign. Only a portion of the muscle edge needs to be obscured for the sign to be positive.

A psoas sign has also been described on MRI in spondylodiscitis and this is discussed separately. 

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1: right-sided from ruptured AAA repair
    Drag here to reorder.
  • Case 2: ruptured abdominal aortic aneurysm
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.