Sequential renography in acute urinary tract obstruction due to stone disease

Area of Science:

• Nephrology
• Nuclear Medicine
• Urology

Background:

• Acute calculus obstruction poses a risk of irreversible renal damage.
• Identifying kidneys at risk is crucial for timely intervention.
• Prospective studies are needed to evaluate diagnostic tools.

Purpose of the Study:

• To prospectively evaluate 99mTc-DTPA renography in identifying kidneys at risk of damage from acute calculus obstruction.
• To determine the correlation between renographic findings and the need for intervention.
• To assess the reversibility of renal function impairment after calculus management.

Main Methods:

• Prospective study of 76 patients with acute calculus obstruction.
• Utilized 99mTc-DTPA renography to assess renal function and obstruction.
• Correlated renographic obstruction with the requirement for intervention and changes in relative renal function.

Main Results:

• A significant relationship was found between renographic obstruction and the need for intervention.
• Stones >5 mm were associated with obstruction, reduced function, and intervention.
• 14 patients had >7% relative renal function drop; 12 normalized after stone treatment.
• 2 patients with persistent impairment had <25% overall renal function and prior treatment.
• No de novo cases experienced permanent ipsilateral renal function loss.

Conclusions:

• Renography criteria for intervention in acute calculus obstruction are well-founded.
• Achieving a stone-free state after primary treatment is critical for preserving renal function.
• Renography is recommended for stones >5 mm, in the middle/upper ureter, or when discharged with residual stones.