Indian Journal of Pain

: 2020  |  Volume : 34  |  Issue : 3  |  Page : 160--163

A comprehensive review of complications following ultrasound-guided blocks: “Continue D'avancer”

Suman Choudhary, Ashok Kumar Saxena, Megha Bajaj, Anwesha Banerjee 
 Department of Anaesthesiology and Pain Medicine, University College of Medical Sciences, GTB Hospital, University of Delhi, New Delhi, India

Correspondence Address:
Dr. Suman Choudhary
377 Kamla Nehru Nagar, Chopasani Road, Jodhpur - 342 001, Rajasthan


The use of ultrasound-guided (USG) technique for regional blocks is a well- established method in regional anaesthesia with the added advantage of providing real-time images of the plexus and nerves and surrounding structures, while significantly minimizing complications. Even if the evidence is in favour of USG guided blocks suggesting that the complications and frequency of complications are significantly lower, this review article is all about few complications that have been published so far in the scientific literature. The complications encountered following USG guided blocks has been categorised into two broad headings: technical and non-technical (neurological, haematological, miscellaneous) in this article.

How to cite this article:
Choudhary S, Saxena AK, Bajaj M, Banerjee A. A comprehensive review of complications following ultrasound-guided blocks: “Continue D'avancer”.Indian J Pain 2020;34:160-163

How to cite this URL:
Choudhary S, Saxena AK, Bajaj M, Banerjee A. A comprehensive review of complications following ultrasound-guided blocks: “Continue D'avancer”. Indian J Pain [serial online] 2020 [cited 2021 Jan 16 ];34:160-163
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The use of (USG) ultrasonography technique for regional blocks is a well-established method in regional anesthesia, is still rapidly evolving, and is most useful in regional anesthesia with the added advantage of providing real-time images of the plexus and nerves and surrounding structures while significantly minimizing complications. Undoubtedly, we have come a long way since the use of USG in regional anesthesia, when it was first used in 1978 by La Grange et al., who performed supraclavicular brachial plexus block (SCB) with a Doppler ultrasound and blood flow detector.[1] In this very first innovative approach, a Doppler blood flow detector device was utilized to target the third division of subclavian artery, thus ensuring a safe approach for SCB. Hence, La Grange et al. predicted almost 42 years ago that USG technique would be precise without complications. Unfortunately, this research paper did not have much impact on our clinical management because USG facilities that time were very limited.

Even if the evidence is in favor of USG-guided blocks suggesting that the complications and frequency of complications are significantly lower, this review article is all about few complications that have been published so far in the scientific literature till October 29, 2020, while performing USG-guided nerve blocks and hence an attempt has been made to summarize the same.

The use of USG has ensured that performing nerve blocks is relatively easy, with a high degree of precision and reliability, and, undoubtedly, USG guidance has made nerve blocks a technically feasible, safe, and efficacious option; however, still, the scientific literature reflects few complications associated with the use of USG for nerve blocks.[2]

The complications encountered following USG-guided blocks can be categorized into two broad headings: technical and nontechnical (neurological, hematological, and miscellaneous) as mentioned in [Table 1]:{Table 1}

Technical complications

Agreeably, technical complications can be encountered even with the ability to appreciate the nerves and their adjacent structures clearly, determine the location of the needle tip, and observe the spread of local anesthesia (LA). Reports of inadvertent, painless, and uncomplicated intraneural injections during ultrasound-guided blocks are few of such encountered technical complications. Schafhalter-Zoppoth et al.,[3] Sandhu et al.,[4] Russon and Blanco,[5] and Zetlaoui et al.[6] analyzed the videos of around 60 ultrasound-guided blocks performed by trainees and concluded that the most common errors while performing nerve blocks using ultrasound are failure to recognize the maldistribution of LA, failure to recognize the needle tip before injection, and poor choice of needle insertion site and angle, preventing needle visualization. All these reports solely object the main limitation of ultrasound technology, that is, dependence on the operator.

It is interesting to note that in the 2008 issue of Anesthesiology, Hadzic et al. suggested limitation in the technology, rather than a lack of expertise, as the additional obstacle in reliably detecting an intravascular injection during ultrasound-guided nerve blocks.[7] The utility and safety of USG over traditional techniques for administering truncal blocks are also not substantiated with enough randomized controlled trials. Ultrasound guidance may increase the success rate of these blocks and is expected to reduce intraperitoneal needle placement or hollow viscous injury, but there is no Level I/II evidence to prove this.

Risk of developing complications cannot be eliminated even with the use of USG as per practice parameter of the American Institute of Ultrasound in Medicine (AIUM).[8] The complication rates in the use of USG to guide vascular access procedures, are similar to those reported using traditional nerve localization tools.[8]

Ultrasound guidance alone using the gray scale may be incapable of identifying and thus avoiding injury to, vascular structures. According to the results of a simulation training study conducted by Zhang et al. on USG-guided hip joint injection, it was noted that the incidence of accidental arterial puncture may be as high as 22% with the use of USG guidance alone.[9]

Hence, obviously to prevent vascular injury, it has been repeatedly advised that incorporation of Doppler imaging in addition to ultrasound helps to identify vessels during needling in high-risk patients, especially in those patients with a bleeding tendency or on anticoagulant therapy.[10]

In few of the blocks, such as, adductor canal block, 20–30 mL dose of LA used may produce quadriceps weakness.[11] Other blocks such as saphenous nerve block is a pure sensory block, so volume required is only up to 5–10 mL, but if by error a large volume such as 20–30 mL is used, then it will spread and block the sub-sartorial plexus located beneath the sartorius muscle and superior to the vastus medialis, and this plexus can get blocked with the use of the large volume of drug.[11] Hence, ultrasound guidance can help in guiding and ensuring that lower volumes of drugs are used while performing the block. Moreover, in a recent study on the retrospective analysis of USG-guided blocks, Yeniocak and Canbolat concluded that there would be reduction in total LA volume, which is in direct proportion with the total experience of the anesthesiologist.[12]

 Nontechnical Complications

Neurological complications

In an interesting study conducted by Fredrickson and Kilfoyle[13] where 1010 consecutive Ultrasound-guided peripheral nerve blocks were performed in patients undergoing orthopedic surgery, which included single-shot and continuous interscalene, supraclavicular, infraclavicular, femoral, and sciatic nerve blocks, the rate of postoperative neurological complications was similar to the low rates previously reported with traditional techniques, possibly reflecting the fact that most postblock neurological complications are the result of nonblock-related causes. In this study, the results suggested that patients were associated with post-block neurological symptoms in 8.2%, 3.7%, and 0.6% at 10 days, 1 month, and 6 months, respectively, following the USG blocks. Most of these symptoms had causes that seemed unrelated to the nerve block. The incidental elicitation of paresthesia (defined as electric shock-like sensation) was associated with an increased risk of neurological sequelae. The neurological damage in these cases could be explained by the needle nerve trauma as the elicitation of paresthesia is generally regarded as being indicative of needle–nerve contact. These results suggested to provide informed consent to all patients by anesthetists performing both ultrasound- and nonultrasound-guided nerve blocks.[13]

Similarly, in another study, Bilbao Ares et al.[14] conducted an observational follow-up on 121 patients, on whom 96 interscalene blocks and 22 supraclavicular blocks were performed. The results showed that postoperative neurological symptoms were detected in 9.9% of the patients during the 1st week following the blocks. After 3 months, the symptoms persisted in nine patients (7.4%) and in four patients (3.3%) even after 1.5 years. The nerve damage was confirmed using electromyogram.[14]

Considering the results of the above-stated studies, it becomes a mandatory prerequisite to clearly explain to the patients and take a written informed consent about the possible neurological complications and its permanence, before performing these blocks.

Pneumothorax as a complication

Gauss et al.[15] in an interesting study conducted 6366 periclavicular nerve blocks (2963 infraclavicular and 3403 supraclavicular) under USG guidance and concluded that despite the use of USG guidance, pneumothorax occurred at a rate of 0.06% for periclavicular blocks. Overall, Gauss et al. noted three cases of pneumothorax, suggesting that despite USG guidance, iatrogenic injury to the pleura can still occur with either infraclavicular block or supraclavicular block.[15]

Intravascular injection

Another rare complication presented by Loubert et al.[16] is a case of accidental intravascular injection of LA during the axillary block, which occurred despite the use of USG guidance in a 57-year-old female, ASA grade I, who was scheduled to undergo right wrist trapeziectomy under regional anesthesia. This case demonstrated that although proper use of USG may increase safety compared with that of landmark-guided peripheral blocks, the risks associated with the injection of large amounts of LA agent are not entirely eliminated, as in this case a small amount of LA agent seems to have got infused accidently intravascularly. A volume of 15 mL of LA was administered on the lateral aspect of the axillary artery, while ensuring that after aspiration of every 5 mL was negative for blood. Hence, the use of USG does not obviate the need for standard safety measures and may alter the effectiveness of traditional signs of intravascular injection.

In another retrospective study by Schafhalter-Zoppoth et al.,[3] impalement of femoral nerve and intraneural injection of LA have been reported following USG-guided femoral nerve block.

Intraperitoneal complications

In the opinion of Hebbard et al.,[17] complications such as intraperitoneal injection, liver trauma, and catheter breakage have been reported during the administration of transversus abdominal plane (TAP) block; however, with the use of USG, the incidence of complications has reduced considerably. A very recent meta-analysis and systematic review of randomized controlled trials conducted by Foldie et al.[18] on TAP block as a part of multimodal analgesia in bariatric surgery, concluded that there were only three complications out of 340 USG-guided procedures. These three nonsevere complications included two cases of hematoma at injection site and one case of severe pain at the site of injection.

Vascular complications

In an interesting series of 488 patients undergoing total knee arthroplasty, Shin et al. reported 3% of patients having inadvertent removal of peripheral catheter and small vascular punctures in 3% of the patient population.[19]

Adductor canal compression syndrome

The unique anatomy of each patient should be evaluated before planning and performing a particular block, with a typical example being adductor canal compression syndrome, which is an extremely rare cause of arterial insufficiency of the lower extremity. Its exact cause of compression remains unidentified, while in few cases, anomalous embryologic musculotendinous fibrous bands have been the reported cause.[20]

An interesting study by Voskeridjian et al. on the evaluation of complications following USG-guided regional block anesthesia in outpatient hand surgery, involving 713 patients, concluded that there were no clinically significant pulmonary or neurological complications. The total follow-up of these patients was 2 weeks. In addition to this work by Voskeridjian et al., there are various other studies on USG-guided nerve blocks in decade reporting almost zero complications.[21]


The immense benefits of performing nerve and plexus blocks under direct visualization with the help of the latest USG technology are rapidly helping anesthesiologists and pain physicians in their day-to-day practice. Despite scarcely any of the above-stated complications following USG guidance, it still provides accuracy, safety, and reliability, along with the overall reduction of time of the performance of the block. A specific approach of “continue d'avancer” (keep moving forward) is more likely to improve the safety of regional anesthesia as an evidence-based integration of USG technology into the existing and emerging monitoring and practice protocols during the administration of regional anesthesia. This task should be incumbent upon the leadership of organized anesthesia societies as well as individual anesthesiologist and pain physician, to secure the future of safe regional anesthesia.

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Conflicts of interest

There are no conflicts of interest.


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