Treatment of Renal Papillary Necrosis
The treatment of renal papillary necrosis prioritizes immediate assessment for infected obstruction requiring emergent drainage, followed by endoscopic retrieval of sloughed papillae to prevent recurrent obstruction and sepsis. 1
Immediate Assessment and Risk Stratification
The first critical step is determining whether infected obstruction (pyonephrosis) is present by checking for fever, leukocytosis, and signs of sepsis, as this represents a urologic emergency requiring drainage within hours, not days. 1 Obtain CT imaging to evaluate for hydronephrosis and perinephric fat stranding, which together confirm obstruction requiring intervention. 1
A critical pitfall: do not assume perinephric fat stranding is benign—it always indicates active pathology requiring investigation, particularly in high-risk patients such as diabetics. 1 Additionally, do not rely on the absence of hematuria to rule out significant papillary injury, as up to 25% of cases lack hematuria despite substantial papillary damage. 1
Emergent Interventions for Infected Obstruction
For patients with infected obstruction, emergent percutaneous nephrostomy is indicated, with patient survival rates of 92% versus 60% with medical therapy alone. 1 The presence of perinephric fat stranding combined with fever or sepsis mandates emergent decompression within hours. 1
When placing drainage, prefer antegrade nephroureteral catheter placement over double-J stents due to the risk of mucus plugging, particularly in patients with ileal conduits. 1 This distinction is important as standard DJ stenting may be inadequate in the acute setting when necrotic debris is present.
Definitive Management: Endoscopic Retrieval
After initial stabilization with DJ stenting in patients who do not respond to intravenous antibiotics, perform retrograde pyelography (RGP) at 3 weeks to identify filling defects in the pelvicalyceal system. 2 Retrograde intrarenal surgery (RIRS) should be performed to retrieve necrosed papillae from the collecting system, as this prevents ureteric obstruction leading to urosepsis and reduces future episodes of pyelonephritis. 2
In a series of 187 diabetic patients, necrosed papillae were successfully retrieved in 83 patients (46.1%) by RIRS, with only 3.8% experiencing recurrent pyelonephritis during follow-up. 2 Notably, 41% of patients without hydronephrosis still had necrosed papillae in the collecting system, emphasizing that the absence of obstruction does not exclude the need for endoscopic evaluation. 2
The advantage of RIRS over simple DJ stenting is that it directly addresses the source of potential obstruction by removing necrotic tissue, rather than merely bypassing it. 2 This is particularly important in diabetic patients with compromised renal function where contrast studies are limited. 2
Surgical Debridement Indications
Surgical debridement is reserved for specific scenarios: persistent obstruction despite drainage, uncontrolled infection despite adequate drainage, or massive hemorrhage unresponsive to conservative measures. 1 Management may range from ureteral catheterization to nephrectomy in severe cases with acute fulminating disease. 3
Diagnostic Considerations
CT imaging is superior to intravenous urography for detecting the full range of features, including contrast-filled clefts in the renal medulla, non-enhanced lesions surrounded by rings of excreted contrast, hyperattenuated medullary calcifications, and filling defects in the renal pelvis or ureter. 4 Multi-detector row CT with thinner sections and multiplanar reformation allows earlier detection when effective treatment can reverse the ischemic process. 4
In pediatric patients with sickle cell disease presenting with hematuria, retrograde pyelography can identify characteristic signs (ball-on-tee sign, clubbed calyces, blunted papillary tips) without requiring CT and its associated radiation exposure. 5