After partial pregnancy (d c). why the do biopsy test? thanks for your answers.

Need to remove the tissue completely: It is important to make sure that there is no placental trophoblastic disease left in the uterine cavity sometimes a pregnancy could result in a tumorous type of benign persistence of placental tissue this is a difficult problem to treat and it is best to remove all the tissue with d and c to remove and to ensure that there is no more chorionic villa or placental tissue in the uterus.