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The number of pus cells in urine 6-8cell/HPF is Normal, Ti is good that there is no bacterial groth in the culture, this rules out any infection which can cause cystitis
... But Normally the Urine will not contain any amount of RBC, since 8-10 cell/HPF is seen , you needed to investigated further to rule out AGN ( acute glomerulo nephritis
) and rule out kidney
diseases,, even though you are on warfarin
, there must not be any RBC, repeat the test and consult the Phycisian for further treatment..