It is known that Tuffier's line intersects the spine at the L4 spinous process or at the L4-L5 intervertebral space. Full term parturient women undergo various physical changes. Therefore, determining the vertebral level with Tuffier's line based on palpation inevitably is not very accurate. The aim of this study was to use ultrasound to verify the difference between vertebral levels for the palpated Tuffier's line in parturient and non-parturient women in the lateral decubitus position.

We consecutively enrolled 40 parturient women at 37-41 weeks of gestation and 40 non-parturient women scheduled for regional anesthesia. In the left lateral position, the location of the vertebra was identified using ultrasonography. We marked every intervertebral space from L5 to L2 vertebra, divided each spinous process into two equal parts, and numbered the spaces sequentially from 1 to 9. We drew a Tuffier's line by palpating, recorded the vertebral level that this line intersected.

The mean value of an arbitrary number of vertebral level of Tuffier's line was 6.4 ± 0.9 in the non-pregnant group and this represents L4-lower vertebral level. In the pregnant group, the mean value was 3.0 ± 1.0 which represents L3-lower vertebral level. There was a significant difference between the two groups (P < 0.05).

We compared using an available ultrasound technique the vertebral levels intersected by the palpated Tuffier's line between parturient and non-parturient women and found that the vertebral levels were more cephalad in the parturient women compared to the non-parturient women.