A 34 y.o. woman in her 29-th week of pregnancy, that is her 4-th labor to come, was admitted to the obstetric department with complaints of sudden and painful bloody discharges from vagina that appeared 2 hours ago. The discharges are profuse and contain grumes. Cardiac function of the fetus is rhytmic, 150 strokes in the minute, uterus tone is normal. The most probable provisional diagnosis will be:
Placenta presentation?