Preprocedural ultrasonography as an adjunct to landmark technique for identification of epidural space in parturients for labor analgesia

Background: Pregnancy-induced softening of tissues and ligaments may increase the false-positive rates when identifying the epidural space in parturients by the landmark technique. To mitigate these problems, Ultrasonography (USG), which has now become the eye of anesthesiologists, can be used as a reliable tool to facilitate more accurate epidural needle placement in parturients. This study was conducted to know the efficacy of USG when compared to the traditional landmark method.

Methods: After the approval from the institutional ethics committee and CTRI registration, 62 parturients of ASA-2 requesting labor analgesia were randomized into 2 groups of 31 each: Group-L (conventional landmark technique) and Group-U (preprocedural USG done before epidural). In group-U, Tuohy's needle was introduced through the USG predetermined insertion point and epidural space was located using the LOR technique.

Results: USG increased the success rate of epidural at first attempt from 51.6% in group "L" to 87% in group "U." Fewer needle attempts (P-value - 0.001) were required in group "U" as compared to group "L." No accidental dural puncture in group-U, compared to 2 in group-L. Mean Depth of epidural space (cm) ultrasound depth (UD) = 3.89 ± 0.45 cm and needle depth (ND) = 4.05 ± 0.37 cm. Side effects profile in the ultrasound group was better.

Conclusion: Preprocedural ultrasonography is a simple safe, accurate tool with less number of attempts to determine the needle insertion site, decrease the incidence of accidental dural punctures, and assess epidural space depth in parturients.