Risks and Complications

Ultrasound in itself is a non-invasive modality for which there are no absolute contraindications.  With regards to safety, the US Food and Drug Administration has noted that while there are no known risks, ultrasound energy can heat tissue and have other biologic  effects.  In addition, ultrasound can produce small pockets of gas (cavitation) in body tissue and fluids.  The long term effects of heat and cavitation are not know.   However, the use of ultrasound for regional anesthesia and vascular access does not eliminate the potential for complications.

Documented complications of UGRA include:

•Vascular puncture
•Local Anesthetic toxicity (seizure, cardiac arrest)
•Venous thrombosis/Hematoma
•Neurologic complications (brachial plexus injury, Horner syndrome)


Not all regional anesthetics have the same level of difficulty.  The potential for complications is often increased when 1) the block is deep in the tissue, reducing the effectiveness of the ultrasound image because of attenuation, 2) the block carries an increased risk of pneumothorax or neuraxial injection, such the supraclavicular and interscalene blocks, and 3)blocks that involve small nerves that lack distinct acoustic impedance differences with the surrounding tissues, such as those in the elbow and ankle, and 4) procedures that involve the placement of a catheter.  Additionally, patient related factors such as obesity can make a block more difficult.

Perhaps the most important factor in reducing or eliminating complications is the training and experience of the provider.  Since there are presently no established training standards for performing ultrasound-guided procedures (only recommendations), the level of expertise varies greatly among practitioners.  A joint committee made up of the American Society Regional Anesthesia and Pain Medicine and the European Society of Regional Anaesthesia and Pain Therapy recognized a defined skill set that would facilitate proficiency with UGRA.  The skills were divided into four major categories 1) understanding device operations, 2) image optimization, 3) image interpretation, and 4) visualization of needle insertion and injection.  Difficulty with skill set number four, visualization of needle insertion and injection has been cited in several journal articles as a common problem with individuals first learning to perform blocks with ultrasound.


 Sites BD, Chan VW, Neal J.et al. The american society of regional anesthesia and pain medicine and the european society of regional anesthesia and pain therapy joint committee recommendations for education and training in ultrasound-guided regional anesthesia. Reg anesth Pain Med. 2009; 34:40-46.

Brull R, McCartney CJL, Chan VW, Hossam E. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007; 104(4):965-974.

Bhatia A, Lai J, Chan VW, Brull R. Case report: pneumothorax as a complication of the ultrasound-guided supraclavicular approach for brachial plexus block. Anesth Analg. 2010; 111.(3):817-19.

Loubert C, William SR, Helie F, Arcand G. Complications during ultrasound-guided regional block: accidental intravascular injection of local anesthetic. Anesthesiology. 2008; 108(4):759-760.

Sites BD, Gallagher JD, Cravero J, Lundberg, J Blike G. The learning curve associated with a simulated ultrasound-guided interventional task by inexperienced anesthesia residents. Reg Anesth Pain Med. 2004; 29:544-548.



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