Final answer:
The contraindication to external uterine massage is when the placenta is still undelivered. It can lead to complications such as retained placenta, severe bleeding, infection, and uterine inversion. Hence, it is important that healthcare providers verify placenta delivery before performing a uterine massage.
Step-by-step explanation:
The contraindication to external uterine massage is the presence of an undelivered placenta. After childbirth, the uterus normally contracts to help expel the placenta and reduce bleeding. However, a uterine massage should not be performed if the placenta has not yet been delivered. This is because the manipulation could lead to parts of the placenta being retained inside the uterus, which can cause severe complications such as hemorrhage, infection, and uterine inversion. Healthcare providers should ensure that the placenta has been completely delivered before attempting any form of uterine massage to promote contraction and involution.