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Bleeding due to period is generally heavy and bright red in color and contains clots in it.
is more reliable than urine test, thus repeat test should be done with blood only.
If pregnancy is excluded, you should get your self examined by a Gynecologist to find out other causes like PID, infection and cervical cancer
etc. and treatment accordingly.
Hope you found my response to your query informative and helpful.
With good wishes,
Dr.Chandra Shekhar Sharma