What are the common causes of flank pain occurring shortly after ureteral stent removal?

Causes of Flank Pain After Ureteral Stent Removal

Flank pain after ureteral stent removal most commonly results from transient ureteral edema, mucosal irritation from the indwelling stent, or residual inflammation of the collecting system—all of which typically resolve spontaneously within days to weeks. 1, 2

Primary Mechanisms of Post-Removal Flank Pain

Mucosal Trauma and Inflammation

• Mechanical irritation from the stent causes urothelial inflammation that persists temporarily after removal, manifesting as flank discomfort 2
• The ureter requires time to recover from chronic contact irritation, with symptoms gradually improving over 1-2 weeks 1, 3
• Transient edema at the site of stent contact can cause temporary obstruction-like symptoms without true mechanical obstruction 2

Residual Collecting System Changes

• Approximately 5.5-5.7% of patients develop or worsen hydronephrosis even with a stent in place, which may become symptomatic after removal 1, 3
• Pre-existing hydronephrosis that was incompletely resolved by stenting can cause persistent flank pain post-removal 1

Serious Complications Requiring Urgent Evaluation

Infection and Obstruction

• Fever (≥38.3°C) with flank pain, leukocytosis >14,000/mm³, or sepsis signs mandate urgent imaging and possible re-intervention 4, 5
• Stent-associated urinary tract infections occur in 11-19% of colonized stents and may manifest after removal 4
• Obstructive pyelonephritis requires urgent decompression (stent replacement or percutaneous nephrostomy) combined with IV antibiotics, improving survival from 60% to 92% 4

Structural Complications

• Urinoma formation from unrecognized ureteral injury during stent placement presents as worsening flank pain and requires CT imaging with delayed urogram 6
• Ureteral stricture can develop from prolonged stenting (especially >3 months), causing obstruction after removal 3, 7
• Stent fragmentation (10%) or migration (8-9.5%) during removal can leave retained fragments causing ongoing symptoms 1, 3, 7

Diagnostic Approach

Clinical Red Flags Requiring Imaging

• Fever, increasing pain, or signs of sepsis warrant immediate CT with delayed imaging (urogram) to exclude obstruction, urinoma, or infection 6, 5
• Persistent pain beyond 2 weeks should prompt renal ultrasound to assess for hydronephrosis 1, 3
• Leukocytosis or elevated creatinine necessitates urine culture and consideration of obstructive uropathy 4, 5

Imaging Modalities

• CT urogram is the gold standard for detecting ureteral injury, stricture, or urinoma (contrast extravasation on delayed images) 6
• Renal ultrasound provides radiation-free assessment of hydronephrosis and is appropriate for initial evaluation of uncomplicated pain 5

Management Strategy

Conservative Management (Mild, Uncomplicated Pain)

• NSAIDs (diclofenac, ibuprofen) are first-line for renal colic-type pain, using the lowest effective dose 5
• Adequate hydration and observation for 1-2 weeks is appropriate for mild symptoms without red flags 1, 2
• Opioids are second-line when NSAIDs are contraindicated 5

Urgent Intervention Required

• Immediate decompression (retrograde stent or percutaneous nephrostomy) plus IV ceftriaxone 1-2g for any patient with fever ≥38.3°C, leukocytosis >14,000/mm³, or sepsis 4, 5
• Ureteral stenting or percutaneous drainage for enlarging urinoma, persistent fever, or worsening pain suggesting complication 6
• Obtain urine and blood cultures before initiating antibiotics, then adjust based on susceptibility 4, 5

Common Pitfalls to Avoid

• Do not dismiss fever as "normal post-stent"—this represents infection until proven otherwise and requires urgent evaluation 4, 7
• Do not delay imaging in patients with severe or worsening pain, as ureteral injury or obstruction can lead to renal loss if untreated 6
• Ensure stent was completely removed—retained fragments occur in 1.9-10% and cause ongoing symptoms requiring cystoscopy 1, 3, 7
• Consider stent duration—stents indwelling >3 months have significantly higher complication rates including encrustation (21.6%) and stricture formation 3, 7