Ultrasound Case 074


An 18 year old man presents with fevers, right loin pain and dysuria. He has pyuria. You wonder about pyelonephritis or even an infected obstructed kidney so take a look with ultrasound.

Describe and interpret these scans

Image 1: Video taken in longitudinal section of the right kidney and psoas muscle.

A heterogenous hypoechoic mass is seen most obviously lying within the psoas muscle. It can be seen extending into the retroperitoneal space between the kidney and psoas and also involves the renal parenchyma.

LITFL Top 100 Ultrasound 74 Key to image 01


Renal abscess with retroperitoneal extension and psoas involvement

Psoas abscess is a rare pathology. It may occur from haematogenous or lymphatic spread, contiguous extension from adjacent infection or occur from traumatic inoculation from penetrating injury. In this case the abscess was extensive involving the renal parenchyma, the retroperitoneal space between the kidney and psoas and the psoas muscle itself. It was not clear whether the origin of the abscess was the kidney with spread to psoas, or the psoas with spread to the kidney. The organism grown both from urine and percutaneous image guided aspiration of the psoas collection grew Escherichia coli perhaps favouring direct extension from the kidney.

Further reading



An Emergency physician based in Perth, Western Australia. Professionally my passion lies in integrating advanced diagnostic and procedural ultrasound into clinical assessment and management of the undifferentiated patient. Sharing hard fought knowledge with innovative educational techniques to ensure knowledge translation and dissemination is my goal. Family, wild coastlines, native forests, and tinkering in the shed fills the rest of my contented time. | SonoCPDUltrasound library | Top 100 | @thesonocave |

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.