Abstract

Abstract

Study Type - Prognosis (cohort) Level of Evidence
What's known on the subject? and What does the study add?

Several small series studies have looked at the natural history of asymptomatic renal stones. The number of subjects in these studies ranged from 24 to 300 and duration of follow-up ranged from 19.4 to 52.3 months. The reported incidences of spontaneous passage, progression and intervention were 3 to 15%, 33 to 77% and 7 to 26%. This study reports on the natural history of asymptomatic stones with an average size of 5.7 mm which were smaller in size than those reviewed in other series. The findings were that the incidence of spontaneous passage was higher than in other series at 20% and that the incidence of intervention was low at 7.1%. This study found that stones that were less than 5 mm in diameter were significantly more likely to pass spontaneously than stones that were larger and there were no other significant differences in the outcomes when stratified according to the initial size and location of stones.

OBJECTIVE:

• To evaluate the long-term outcomes of patients undergoing observation of asymptomatic renal calculi.

PATIENTS AND METHODS:

• This is a retrospective review of 50 patients with 85 stones undergoing observation with annual imaging from January 2005 to December 2009.
• The incidences of spontaneous stone passage, stone progression and intervention were evaluated and assessed for statistical difference according to initial size and location of stone.
• Percutaneous nephrolithotomy, shock wave lithotripsy and ureteroscopy were performed when patients developed complications from the stones.

RESULTS:

• Patients were followed up for a mean of 46 months. Sixteen percent had bilateral stones and 38% had multiple stones.
• The average stone size was 5.7 mm and 31%, 26% and 43% of the stones were located in the upper, middle and lower pole respectively.
• Overall incidences of spontaneous passage, progression and intervention were 20%, 45.9% and 7.1% respectively.
• Stones measuring 5 mm or less were significantly more likely to pass (P= 0.006).
• There was no significant difference in the incidence of passage according to the initial location of the stone (P= 0.092). There was no significant difference in intervention or progression according to the initial size (P= 0.477 and 0.282 respectively) or location of stone (P= 0.068 and 0.787 respectively).

CONCLUSIONS:

• Patients with asymptomatic renal stones may be managed conservatively in view of low risk of intervention (7.1%).
• Annual imaging should be performed as half of these stones will progress in size.

© 2011 THE AUTHORS. BJU INTERNATIONAL © 2011 BJU INTERNATIONAL.

BJU Int. 2012 Feb;109(4):622-5. doi: 10.1111/j.1464-410X.2011.10329.x. Epub  2011 Aug 18

PMID: 21851532 [PubMed - as supplied by publisher] 

Comment

Comment

50 patients with 85 uncomplicated asymptomatic renal stones were followed up for a mean of 46 months. Within that time  7.1% of the stones underwent some form of intervention: 4 SWLs for stone caused obstruction at the ureteropelvic junction or in the ureter and 1PNL

I liked this paragraph in the discussion section because it offers answers to the questions some asymptomatic-not-yet-patients may ask:

“Despite the limitations, this study raises the awareness that conservative management of asymptomatic small renal stones is a viable option with low incidence of intervention and 20% chance of spontaneous passage. As half of these stones will undergo progression, it is important to keep patients on follow-up with annual imaging. Patients should be offered prophylactic intervention when stones exceed 10 mm because of the 14.3% risk of complications. Patients with stones exceeding 5 mm should be informed of the 9.5% risk of complications and of the European Association of Urology recommendations for prophylactic intervention when stones exceed 7 mm because of the low rate of spontaneous passage.”

Peter Alken