Ultrasound imaging improves learning curves in obstetric epidural anesthesia: a preliminary study

Epidural anesthesia may be difficult in pregnancy. We intended to evaluate the teaching possibilities of ultrasonography as a diagnostic approach to the epidural region.

Two groups of residents performed their first 60 obstetric epidurals under supervision. One proceeded in the conventional way using the loss of resistance technique (control group = CG). The other group proceeded in the same way but was supported by prepuncture ultrasound imaging, giving them information about the optimal puncture point, depth and angle (ultrasound group = UG). Success was defined as adequate epidural anesthesia requiring a maximum of three attempts, reaching a visual analogue scale score of less than 1, while neither changing the anesthesia technique, nor starting at another vertebral level. In addition, intervention by the supervisor was defined as failure.

In the CG we observed a success rate of 60% +/- 16% after the first ten attempts followed by a nearly continuous rise of the learning curve. Within the next 50 epidurals the rate of success increased to 84%. In the UG the rate of success started at 86% +/- 15%. Within 50 epidural insertions it rose up to a level of 94%. The difference between the two groups remained significant (P < 0.001).

Using ultrasound imaging for teaching epidural anesthesia in obstetrics we found a higher rate of success during the first 60 attempts compared to conventional teaching. We believe this shows the possible value of ultrasound imaging for teaching and learning obstetric regional anesthesia.