Which of the following circumstances is most likely to cause uterine atony and lead to PP hemorrhage?

Urine retention

Urine retention causes a distended bladder to displace the uterus above the umbilicus and to the side. which prevents the uterus from contracting. The uterus needs to remain contracted if bleeding is to stay within normal limits. Cervical and vaginal tears can cause PP hemorrhage but are less common occurrences in the PP period.