In this case the working diagnosis is most likely to be placental abruption with the history of constant pain and bleeding, no suggestion of a low lying placenta and no scar pain.
Placental abruption results from early separation of the placenta from the uterus and can result in significant bleeding and fetal compromise, in some cases intrauterine death.
The extent of bleeding does not always match the clinical status of the patient and this may be due to significant concealed bleeding within the uterus as shown in the picture.