My husband and I are extremely confused. Our 3 year old son has just had 2 sweat tests, which we were hoping would rule out CF (the only symtom he has is a rectal prolapse) however, the first test came back as 72, and the second as 47. We don't understand how these results could be so different ?? His doctor said that diagnostic is usually 70+, and that his 47 is reassuring in comparisson. He now has to go for a third test tomorrow to confirm or rule out CF. I really dont know what to think, is the 47 reassuring ?? or is the 72 the more reliable of the 2 ?? Should we ask for blood tests reguardless of the 3rd results just to be sure ?? and how come they don't just do bloods in the first place ??Sorry for so many questions, but I feel like I'm stuck between a rock and a hard place, I don't know anyone with CF, and so no one can give me any information !!Thanks in advanceLiz