Background
Urolithiasis is a common condition. It often affects patients in the prime of life causing significant burden to the society. In our study we are interested in determining whether seasonal variation is a risk factor of acute urolithiasis.

Method 
A retrospective study was performed at a tertiary hospital in Canberra, ACT, Australia. Data pertaining to patient demographics, history of renal colic and management were extracted from charts over a 10-year period. Climatic data for the Australia Capital Territory during this period was retrieved from the Australian Bureau of Meteorology and correlated to renal colic presentations.

Results
Data was obtained for 637 patients all with radiologically confirmed calculi of the urinary tract. The median age at diagnosis was 50 years of age. Overall 37.4% of patients had a previous history of urolithiasis and the male to female ratio was 2.8:1. Presentation was most common in the autumn months (32.8%), with the fewest cases of urolithiasis during the winter months (18.7%). At presentations the majority of the calculi were ≤ 5mm and located within the distal ureter. Conservative treatments were instituted more often when stone size was ≤ 5mm. Proximal ureteric calculi were more likely to be treated with surgical intervention.

Conclusion
We demonstrate an association between the presentation of primary urolithiasis and season. A better understanding in the subject may help future health care planning to deal with the seasonal increase in presentations of renal colic to the urology service.