Pam,
I'm sorry I missed your original post.....but in response to your question
+AD4-1.  Is it possible for a woman that has undergone a hysterectomy to have a
retained placental fragment???

The simple response is NO.
The placenta develops and establishes itself on the inner wall of the
uterus.  In a vaginal birth it is expelled by the mom after she delivers her
baby.  In a cesarean birth the physician would remove it after the birth of
the baby.  If a woman has had a hysterectomy, by definition that means her
uterus has been removed.  Even if a fragment of the placenta was retained in
the uterus at that point, the uterus itself would no longer be in the woman
who had a hysterectomy, so the fact that a placental fragment was still
present in the uterus at that point would not be relevant to a discussion of
low milk supply.
Joyce Blangiardo RN, LCCE, FACCE, IBCLC
LamazeLady+AEA-msn.com
Long Island, NY