uterine subinvolution

Uterine atony is a lack of normal tone or strength of the uterine muscle. I would not use these terms interchangably. Atony refers to a condition of the muscle. Subinvolution refers to a condition of the uterus organ.

Subinvolution is slower than expected return of the uterus to its prepregnancy size after childbirth. It is caused by retained placental fragments or pelvic infection. It usually develops after the mother has gone home from the hospital. Signs and symptoms include

• prolonged lochial discharge
  
• irregular or excessive uterine bleeding
  
• pelvic pain or feelings of pelvic heaviness
  
• backache
  
• fatigue
  
• persistent malaise
  
• the uterus feels larger and softer than expected

so my question would be how can you tell the difference between the two post-op....

Whether or not there is infection or retained placenta involved.