Snowmobiling is a common recreational activity in many regions of Canada and other countries with winter snow cover, but snowmobilers are at risk for traumatic injuries.1 I describe here a healthy man who experienced gross hematuria after long-distance snowmobiling. A MEDLINE search yielded no other reports of nontraumatic gross hematuria after snowmobiling.
A 40-year-old man experienced transient, frank, painless gross hematuria after snowmobiling a distance of almost 500 km. He denied any recent flulike illness or injury to the flanks; he also denied difficulty in passing urine and had no burning sensation during urination. No other aspects of the medical history were relevant, and the results of a physical examination were unremarkable. The prostate was not enlarged, and there was no prostate tenderness. Urinalysis revealed brownish urine, 4+ for blood on a urine dipstick (20 to 40 erythrocytes per high-power field) and traces of protein. There were no erythrocytic or granular casts. The symptoms resolved spontaneously within 24 hours. The results of urine culture were negative. Intravenous pyelography, cystoscopy performed 2 days later and abdominal ultrasonography were unremarkable. The results on follow-up urinalysis 2 weeks and 1 month later remained negative. A 24-hour urine collection for calcium, oxalate and uric acid showed no evidence of crystalluria.
Exercise-related urinary abnormalities are common in people engaging in strenuous exercise, contact sports and marathon running. Exercise hematuria occurs in 18% of marathon runners2 and has also been described in players of contact sports and physically active servicemen, especially after severe exertion.3 However, controversy surrounds the source of bleeding after strenuous exercise. Kincaid-Smith4 emphasized that glomeruli are the usual source of bleeding in such cases, frank hematuria of bladder origin being less common. However, Blacklock5 described long-distance runners who experienced profuse hematuria from erosive lesions in the bladder that had been caused by trauma. The source of bleeding in the man described here remains speculative, but it appeared to be from the bladder, as no casts were observed on microscopic examination. Snowmobilers sometimes experience some flank discomfort that is usually attributed to the frequent thrusting movements related to the bumpy ride. I believe that the repetitive impact of the man's partially filled bladder against the bladder base during each thrust caused bladder irritation leading to transient gross hematuria, similar to what has been described in marathon runners. Because snowmobiling is a common recreational activity, this association may be under-recognized.
Malvinder S. Parmar Medical Director Medical Program (Internal Medicine) Timmins & District Hospital Timmins, Ont.