What Causes Burst Of Uterus With Prolonged Bleeding During Labor?

Respected Dr. My wife was admitted in a renowned government hospital for normal delivery as per E.D.D. in morning.while keeping her admitted continue for 3 days . On 3 rd day uterus burst and NBB died ,and due to prolonged bleeding the Lady came to COMA condition.while I should mention for your ready reference that all the general routine check up for previous all the ANC period check up including 2 to 3 time USG as advised by doctor of the same hospital was also healthy and excellent.No previous history of operation / illness.