Objective To study the effects of preoperative phenoxybenzamine (o.p) on preventing epidural- morphine- induced urinary retention and effects of neostigmine on releasing it.Methods 80 patients who received epidural morphine to release postoperative pain were divided into 4 groups randomly and received preoperative phenoxybenzamine (group P， n=20)， neostigmine (i.m) when urinary retention happened (group N， n=20)， both drugs (group U， n=20)， and without drugs (Control， n=20)， respectively.The incidences of urinary retention and release were observed.Results No significant decrease (P >0.05) happened after operation in the incidence of epidural- morphine- induced urinary retention both in the group P and in the group N. Neostigmine(i.m) could significantly release (P< 0.001) the epidural- morphine- induced urinary retention when phenoxybenzamine was administrated preoperatively. Conclusion Preoperative phenoxybenzamine can not prevent epidural- morphine- induced urinary retention. Neostigmine can release the urinary retention only when preoperative phenoxybenzamine is used.
