Researchers say menstrual blood testing could offer a simple, non-invasive alternative to cervical screening.A sanitary pad fitted with a sample strip can detect human papillomavirus, the main cause of cervical cancer.Women could use the test at home instead of attending a clinic. Researchers in China compared menstrual blood samples with clinician-collected cervical samples.The study involved more than 3,000 women aged 20 to 54 with regular periods.Findings were published in BMJ. The pad-based test detected serious cervical cell…