Diagnostic Ultrasound - Abdomen and Pelvis

Pyonephrosis
Diagnoses: Urinary Tract
TERMINOLOGY
• Obstructed renal collecting system containing pus or
infected urine
IMAGING
• Presence of mobile debris and layering of low-amplitude
echoes within dilated collecting system on US
• Dilated collecting system containing intermediate- or highdensity
material on CT
• Enlarged kidney with perinephric inflammatory changes on
CT
TOP DIFFERENTIAL DIAGNOSES
• Sterile hydronephrosis
• Complex renal cyst
• Urothelial carcinoma
PATHOLOGY
• Stagnant urine becomes infected, filled with white blood
cells, bacteria, debris, and pus
KEY FACTS
• Chronic > acute ureteral obstruction
• Etiology
○ Young adult: Calculus or ureteropelvic junction
obstruction or duplicated collecting system more
common
○ Elderly: Malignant ureteral stricture other mechanical
obstruction
CLINICAL ISSUES
• Delay in diagnosis and treatment leads to irreversible renal
parenchymal damage and renal failure
○ Progress to bacteremia or septic shock and can lead to
25-50% mortality
• Symptoms include fever, chills, flank pain
• Most common organism: E. Coli
• Treatment: Percutaneous nephrostomy
• Diabetes is a risk factor for worse clinical outcomes
• Early diagnosis and drainage are crucial to prevent
bacteremia and septic shock
(Left) Debris layers
dependently in a mass-like
fashion st in this case of
pyonephrosis in an adult
patient with multiple sclerosis
on grayscale US imaging.
(Right) Note the twinkling
artifact on the surface of
stone st in this high-PRF
Doppler ultrasound.
(Left) Longitudinal grayscale
and color Doppler US show
abnormal echogenic material
within a mildly dilated
collecting system . Note
absence of internal vascularity
st, helping to distinguish this
from tumor in the renal pelvis.
(Right) Transverse ultrasound
of the kidney with the patient
in the left lateral decubitus
position shows a distinct pusurine
level ſt in the dilated
system in this patient with
prostate cancer and
pyonephrosis.
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