A comparison of the pelvic angle applied using lateral table tilt or a pelvic wedge at elective caesarean section

Abstract

Lateral table tilt or a pelvic wedge are commonly used to reduce inferior vena cava compression during obstetric anaesthesia in the supine position. Direct measurement of pelvic angle allows individual assessment of the effectiveness of these manoeuvres in achieving a tilted position. We observed routine practice during caesarean section after random allocation to one or other of these methods. The anaesthetist managing the case was asked to position the women after induction of spinal anaesthesia using either left table tilt or a wedge under the right hip. We then measured pelvic angle in all women, and the table angle in women who had table tilt. The mean (SD [range]) pelvic angle was 20.2° (8.1° [9°-37°]) in 18 women with table tilt and 21.0° (7.5° [10°-36°]) in 17 women with a wedge. The mean (SD [range]) table angle was 12.4° (3.1° [8°-21°]) in the women with table tilt. There was a significant difference between table angle and pelvic angle in the women with table tilt (p = 0.0003), but no significant difference in pelvic angle between the table tilt and wedge groups. Measurement of table angle does not represent pelvic position adequately in the majority of women. However, this study showed that lateral table tilt and a pelvic wedge were equally effective in producing tilt of the pelvis.