Ultrasound assessment of the sciatic nerve depth and its relationship with anthropometric parameters

Background P = 0.03). A positive relationship existed between BMI measurements and mid-thigh diameter dimensions when compared against nerve depth measurements in patients (r = 0.28, P = 0.007 and r = 0.21, P = 0.04 respectively). The independent predictors of increased sciatic nerve depth included BMI (β = 0.06, P = 0.004), mid-thigh diameter (β = 0.03, P = 0.010) and female gender (β = 0.42, P = 0.008) and ASA Grade III (β = 0.37, P = 0.030). The nerve depth increased progressively from normal weight patients (3.2 cm) to obese patients (4.1 cm) with statistical significance (P < 0.001). The study revealed anatomical variations in 57.8% of the patients. Conclusion: The depth of the sciatic nerve in the popliteal fossa shows a direct correlation with BMI and thigh diameter and gender and ASA classification. The results demonstrate why healthcare providers should perform customized preoperative assessments to maximize the effectiveness of ultrasound-guided blocks especially when treating patients with complex body structures or obesity. Keywords: BMI; Nerve Block; Regional Anesthesia; Sciatic Nerve; Thigh Circumference; Ultrasonography; Citation: Shanmugam PK, Mariyappan S, Kumar VK, Gopalakrishna K, Rathnasabapathy B, Choudhary AK, Periasamy P. Anaesth. pain intensive care 2025;29(5):352-359. DOI: 10.35975/apic.v29i5.2874 Received: April 29, 2025; Revised: May 23, 2025; Accepted: June 26, 2025