Is there a need for extra-length spinal needles for obstetric spinal anaesthesia in obese parturients? A multi-centre study

Background: Neuraxial blocks are often the preferred anaesthetic techniques in obese mothers for caesarean section because of  increased risk of difficult intubation in them. However, these techniques may be challenging possibly because of poor landmark of spinal space and poor selection of spinal needles in them. Objective: To investigate if there is need for extra-length spinal needles in obese parturients during caesarean section. Design: A prospective observational study Setting: Four University Teaching Hospitals in South-Western Nigeria. Subjects: Parturients scheduled for caesarean section under spinal anaesthesia Results: The mean age, weight, body mass index and skin to subarachnoid space depth (SSD) were 31.49 ± 5.12 years, 75.21 ± 14.14 kg, 27.68 ± 5.45 kg/m2 and 6.08 ± 0.98 cm respectively. Of the 485 parturients, 156 (32.2%) were obese. Majority of the obese patients were greater than 30 years of age when compared with those that were under 30 years and this was statistically significant (p= 0.007). Only one obese parturient needed an extra-length spinal needle for skin to sub-arachnoid space depth (SSD) of 10 cm. There was a more positive linear correlation between depth of spinal needle and weight (0.455) than BMI (0.229) Conclusion: Although about one-third of parturients in our study were obese, only one required an extra-length spinal needle. Extra-length spinal needle is rarely needed in our populatio