Epidural pressure was measured in 17 post-partum patients who were receiving prophylactic infusion of saline into the epidural space after an inadvertent dural tap. During the infusion, the mean (+/-SD) epidural pressure was 19.1 (+/-4.3) cm H(2)O. Four patients complained of severe interscapular pain during the infusion. The epidural pressure in these patients was higher than 24 cm H(2)O. Prophylactic infusion of saline into the epidural space failed to prevent postdural puncture headache in 10 patients.