Pregnant 5 months, regular menstruation?

Pregnant 5 months, suddenly there is vaginal bleeding phenomenon, does not belong to menstruation, is not a normal phenomenon, may be signs of threatened abortion, should be timely medical examination b ultrasound, blood hcg and progesterone. If progesterone is low, bleeding is relatively small, b ultrasound shows that there is fetal heart, should supplement progesterone fetal treatment.