How long will a natural miscarriage take? when should all the bleeding pass? 6week old fetus, carried to 13 weeks

A week: At 6 weeks gestation it should take about a week after passing the products of conception for the bleeding, which should be of a tapering off nature, to completely stop. If that is not the case, a transvaginal ultrasound may help to determine, if there are retained products that could get infected and cause sepsis, a life threatening condition.