What are the treatments for a postpartum uterus infection not solved with antibiotics?

Worst case: If antibiotics for what is believed to be post partum infection of the uterus don't work, the symptoms being treated are either not from an infection, or there are bacteria present and/or the environment in the uterus is such that these antibiotics are not effective. The source of an infection needs to be removed, potentially by way of hysterectomy.