Dipstick Testing
Haematuria
Urinary ‘dipstick’ testing is required as part of the routine aeromedical examination to screen for the presence of haematuria. Approximately 2-5% of the population have microscopic haematuria, but only about 0.5% who are under age 70 will have a urinary tract cancer as the cause. A positive dipstick test should be repeated, and if negative, managed expectantly. (Most of these applicants will have a minor glomerular lesion.)
Initial aeromedical management of an applicant with a persistently positive dipstick test involves obtaining phase contrast microscopy of a fresh mid-stream urine sample. The sample must be examined within two hours of being passed; thus individuals more than two hours from a suitable pathology service must travel to a location that has that capability. Because of wide variation between laboratories in reporting urine abnormalities, CASA’s relevant requirement for a ‘normal’ assessment in an applicant found to have microscopic haematuria is for three separate urine tests, all of which have less than 20,000 RBC per ml. Phase contrast microscopy of specimens with crenated cells up to 10,000 per ml, indicating a glomerular origin, are considered to be within normal limits. Cells with a ‘non-glomerular’ appearance are likely to indicate a urothelial
problem. Where there is ‘significant haematuria’ (more than 20,000 RBC per ml in any test), initial urogenital imaging is to be by Ultrasound or Intravenous Pyelogram (IVP), as some 10% of all stones are radiolucent. The requirement for further investigation should be determined on clinical grounds and on the basis of investigation results.
Above is from the Ausi medical hand book. When I was last working in UK we had a few pilots come upto clinic and they had the usual: ultrasound, urinary cytology and microscopy (lab tests on urine) and a flexi cystoscopy (my boss at the time always worried about cancer. - As you can see from the above article vv unlikely to have anything nasty - especially if you don't smoke.)
We see a lot of patients with positive 'urine dip sticks' and are usually found to be inaccurate (the sticks are very sensitive but not specific) - would recommend drinking plenty of fluid prior to the test to ensure hydrated and if possible make sure it's not your first sample of the day.