Ultrasound-assisted versus landmark-guided localisation of the intervertebral space for subarachnoid block in caesarean section in obese parturients: A randomised controlled trial
Keywords:
Ultrasound, Obesity, parturient, subarachnoid block, caesarean sectionAbstract
Background: Traditional reliance on the intercristal line for intervertebral space identification during subarachnoid block in the landmark technique may lead to multiple needle punctures in obese parturients and consequent perioperative adverse events. This study aimed to evaluate whether ultrasound assistance reduces these incidents compared to the landmark technique.
Methods: This single-blind RCT included 60 obese parturients (body mass index ≥ 30 kg/m²) scheduled for elective caesarean section. Participants were randomly allocated to Group A (n = 30) or Group B (n = 30), who received subarachnoid via the landmark technique or with ultrasound assistance for space localisation, respectively. The primary outcome was the total number of needle attempts for a successful block. The secondary outcomes included procedure time, development of postdural puncture headache and chronic low back pain, and patient-reported general health status.
Results: The number of needle attempts was lower in Group B compared to Group A [median (IQR): 1 (1–1) vs 2 (1–3); Hodges–Lehmann estimate of difference −1.0 attempt, 95% CI −1.00 to −0.00004; P < 0.001]. Procedure time was less in Group B (P = 0.03). The occurrence of postdural puncture headache and chronic low back pain were lower in Group B compared to Group A (6.7% vs 30%, P = 0.047 and 16.7% vs 43.3%, P = 0.02, respectively). Among participants with chronic low back pain, the SF-12v2 health survey yielded no significant differences.
Conclusion: Ultrasound-assisted localisation of the intervertebral space may be a useful adjunct to improve success in obese parturients undergoing caesarean section under Subarachnoid block.
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Copyright (c) 2026 Yesmin Akter, Kazi Mahzabin Arin, Saiful Mahmud Tusher, Farzana Zaman Popy, AKM Akhtaruzzaman, Mohammad Shafiqul Islam
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