The normal menstrual cycle ranges between 21 – 35 days , lasts 2 – 4 days , with an average blood loss of 20 – 40 ml per cycle . Abnormal uterine bleeding is defined as changes in the frequency , duration and the amount of blood flow . Menorrhagia is defined as regular , heavy , cyclical  bleeding occurring over several consecutive cycles . Though the exact amount of blood loss is difficult to quantify , most  women who bleed more than 7 days , or use more than 10 towels per cycle or experience night time soiling or daytime embarrassment or have to miss social or work engagements due to periods are said to have    ‘ heavy periods ‘. Objectively,  blood loss more than 80 ml per cycle  is termed as heavy periods or menorrhagia. Although this is an age old definition , this serves the purpose because