IMAGE QUIZ

The Answer
The IVP shows a a left kidney abscess with the white arrows demonstrating air pockets. The left kidney is not functioning, whereas there is apparent good function of the right kidney and evidence of a urogram (black arrow). 

The Question

The image below is an IVP in a patient with fevers. What does the image show (white arrows), and what's the diagnosis?

Explanation

1. Abscesses of of the kidney account for 0.2% of all intra- abdominal abscesses. There are two types of renal abscesses:
• Perinephric abscesses are collections of pus between the renal capsule and Gerota’s fascia; they account for 0.02% of all abdominal abscesses. These abscesses have a poorer prognosis and are more difficult to treat than intrarenal abscess.
• Intra-renal abscess or "Renal carbuncle" – an encapsulated necrotic material within the renal parenchyma.
2. Predisposing factors include diabetes, kidney stones, vesico-uretral reflux, and IV drug abuse.
3. Clinical features: back pain, fever, chills and rigors with loin tenderness.
4. Diagnosis and Treatment

• Imaging: IVP in the old days, ultrasound or CT. Small abscesses are <3cm, medium 3-5 cm and >5cm.
• Gram stain of the aspirated fluid reveals the causative organism in most cases. There is a high correlation between organism grown in urine culture and the abscess. Repeated urine cultures are positive for the causative organism in almost all cases, whereas blood culture may or may not yield positive results
• Treatment:  Antibiotics depending on the etiological agent, empirical therapy for Gram negative bacteria is justified when the causative agent is not isolated. Surgical intervention for cases refractory to medical therapy.