Accuracy of Tuffier’s Line Identification by Palpation Method: Cross-Sectional Comparative Study Among Obese, Pregnant and Control Groups

OBJECTIVE: Performance of safe central neuraxial blocks requires identification of accurate vertebral interspace. This study aimed to evaluate the accuracy of palpation method by confirmation with ultrasound in high-risk groups like obesity and pregnancy. METHODS: This cross-sectional comparative study was conducted after approval from the hospital ethics committee and written informed consent from participants. Participants were enrolled into four groups: normal weight non-pregnant (N), full-term pregnant (P), obese (O) and obese full-term pregnant (PO). Tuffier’s line at L4–L5 interspace was determined by palpation method and marked as P-line. Another examiner blinded to the marking done by palpation method confirmed it by ultrasound. The primary endpoint was to determine the accuracy of the palpation method, defined as true identification of Tuffier’s line at the L4–L5 interspace by confirming it with ultrasound among four groups. Proportion and percentage were computed and analysed the true identification of Tuffier’s line at L4–L5 by chi-square test at 0.008 adjusted level of significance for multiple comparisons. RESULTS: Tuffier’s line identification by palpation method was confirmed by ultrasound scanning at L4–L5 interspace in 75.3% (226/300) of participants. Proportion difference of true identification of Tuffier’s line at L4–L5 by palpation and ultrasound was statistically significant among the groups (p=0.0005). True identification was significantly lower in group PO [36.4%; p=0.0005<0.008] and group O [34%; p=0.0005<0.008] as compared to that in group N. CONCLUSION: Palpation method was found to be the inaccurate surrogate for the L4–L5 vertebral interspace for obesity with or without pregnancy.