Nancy Epstein
  1. Clinical Professor of Neurological Surgery, , School of Medicine, State University of New York at Stony Brook, and c/o Dr. Marc Agulnick, 1122 Franklin Avenue Suit 106, Garden City, NY 11530, United States.

Correspondence Address:
Nancy Epstein,Clinical Professor of Neurosurgery, School of Medicine, State U of NY at Stony Brook, and c/o Dr. Marc Agulnick, 1122 Franklin Avenue Suite 106, Garden City, NY 11530, United States.


Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.

How to cite this article: Nancy Epstein. A perspective on wrong level, wrong side, and wrong site spine surgery. 14-Jun-2021;12:286

How to cite this URL: Nancy Epstein. A perspective on wrong level, wrong side, and wrong site spine surgery. 14-Jun-2021;12:286. Available from:

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Background: Four of the most common “errors” in spine surgery include: operating on the wrong patient, doing the wrong procedure, performing wrong-level surgery (WLS), and/or performing wrong-sided surgery (WSS). Although preoperative verification protocols (i.e. Universal Protocol, routine Time-Outs, and using the 3 R’s (i.e. right patient, right procedure, right level/side)) have largely limited the first two “errors,” WLS and WSS still occur with an unacceptably high frequency.

Methods: In 20 studies, we identified the predominant factors contributing to WLS/WSS; unusual/anatomical anomalies/variants (i.e. sacralized lumbar vertebrae. lumbarized sacral vertebra, Klippel-Feil vertebrae, block vertebrae, butterfly vertebrae, obesity/morbid obesity), inadequate/poor interpretation of X-rays/fluoroscopic intraoperative images, and failure to follow different verification protocols.

Results: “Human error” was another major risk factor contributing to the failure to operate at the correct level/side (WLS/WSS). Factors comprising “human error” included; surgeon/staff fatigue, rushing, emergency circumstances, lack of communication, hierarchical behavior in the operating room, and failure to “speak up”.

Conclusion: Utilizing the Universal Protocol, routine Time Outs, and the 3 R’s largelly avoid operating on the wrong spine patient, and performing the wrong procedure. However, these guidelines have not yet sufficiently reduced the frequently of WLS and WSS. Greater recognition of the potential pitfalls contributing to WLS/WSS as reviewed in this perspective should better equip spine surgeons to avert/limit such “errors” in the future.

Keywords: Lumbar surgery, Multiple intraoperative X-ray/fluoroscopy techniques, Right level, Right patient, Right procedure, Right (Correct) side, Universal Protocols, Avoid Wrong Level (WLS)/Wrong Side Spine Surgery (WSS)


Four of the most common “errors” in spine surgery include: operating on the wrong patient, performing the wrong procedure, operating at the wrong-level (WLS), and operating on the wrong-side (WSS) (i.e. includes wrong site surgery (WSS) as well).[ 1 , 2 , 4 - 10 , 13 , 14 , 16 , 18 , 19 , 20 ] Although routine use of the Universal Protocol, Time-Outs, and the 3 R’s (i.e. right patient, right procedure, right location/side) should largely limit/eliminate the first two “errors,” WLS and WSS still occur with an unacceptable frequency.[ 1 , 2 , 4 - 7 , 10 , 12 , 14 , 16 - 20 ] Here, we reviewed the incidence of WLS and WSS in 20 studies, and looked at the major factors contributing to these “errors;” spinal anomalies/anatomic variants, and failure to obtain adequate intraoperative X-rays/Fluoroscopic images (i.e. inadequate number, inadequate quality, poor/misinterpretation of X-rays/fluoroscopic images). Additionally, “human errors” contributed to WLS/WSS (i.e. including the lack of surgeon/staff preparedness, hierarchical behaviors interfering with honest communication (i.e. failure to “speak up”), fatigue, rushing/ emergent procedures, and others).[ 1 , 2 , 4 - 7 , 10 , 12 , 14 , 16 - 20 ] Our aim in highlighting the main failures contributing to WLS/WSS/WSSS should help limit/eliminate them in the future.


Wrong level spine surgery (WLS) is not that rare. [ Table 1 ].[ 1 , 4 , 8 , 15 ] In 2007, Jhawar et al. and in 2008 Ammerman and Ammerman documented that wrong level cervical diskectomy occurred in from 6.8 to 7.6/10,000 cases/ year, while wrong level lumbar diskectomies occurred in from 4.5 to 12.8/10,000 cases/year.[ 1 , 8 , 15 ] Using the 1995–2005 Joint Commission Sentinel Event Statistics Database, Devine et al. (2010) observed that wrong site spine surgery (WSSS) was the second most frequently encountered adverse event, and determined its frequency was 12.8% (i.e. occurring in 455/3548 spinal procedures); in the literature, the incidence of WSSS varied from 0.9 to 4.5 cases/10,000 spinal operations per year.[ 4 ]

Table 1:

Wrong level spine surgery.



Notably, 50–67% of spine surgeons have directly experienced WLS over their careers [ Table 1 ].[ 12 , 14 , 20 ] Mody et al. (2008) observed that 207 (50%) neurosurgeons had experienced WLS (spinal) once or more during their careers; the overall incidence was 1/3110 spinal cases.[ 14 ] Watts et al. (2019) reported the same 50% incidence of WLS over spine surgeons’ careers, a frequency distinctly unchanged by the 11 year interval between the two studies.[ 20 ] Interestingly, Mayer et al. (2014) reported a higher 67% incidence of WLS involving thoracolumbar procedures over surgeons’ careers; this frequency was somewhat higher utilizing X-ray (56%) alone vs. fluoroscopy (44%) to intraoperatively confirm the correct spinal operative levels.[ 12 ]


Little attention has been given to the 0.3–4.3–15% incidence of initial wrong level exposure (WLE) or unintended level spine surgery (ULS). WLE/ULS is defined by recognizing during the index procedure that the initially exposed level was incorrect, but that this “error” was corrected prior to closure [ Table 1 ]. [ 3 , 12 , 14 ] When Mody et al. (2008) surveyed 415 neurosurgeons, 64 (15%) had at least 1 instance in which a wrong level was initially exposed; in these cases, the “error” was immediately corrected without the need for a second operation.[ 14 ] Such “errors” were attributed to a multitude of factors; rare anatomical variations, failure to identify anatomical landmarks, and obesity/unusual body habitus.[ 12 , 14 ] Dablouk et al. (2019) recommended requiring needle placement in fixed anatomic structures (i.e. facet joint or spinous process) to avoid these “errors”. They also emphasized performing adequate preoperative and intraoperative “Time Outs”, and improving communication between the operating personnel/staff.[ 3 ]


Multiple protocols (i.e. Universal Protocol- JCAHO (Joint Commission on Accreditation of Healthcare Organizations), Time Outs, and the 3R’s) are aimed at avoiding WLS, WSS, and WSSS [ Table 1 ].[ 1 , 2 - 10 , 12 , 14 , 16 - 20 ] Clarke et al. (2008) used the 3 step R protocol (i.e. right patient, right side, and right level), Time Outs, and marking the correct site to avoid WSSS.[ 2 ] Palumbo et al. (2013) recommended not only using the 3 R protocol, but also emphasized that surgeons follow strict regimens to ensure operating at the correct vertebral levels.[ 16 ] In 2020 Devine et al. reevaluated their JCAHO-based Universal Protocol data to better limit/eliminate WSSS.[ 4 ] Nevertheless, several authors observed the continued failure to elminate WSS that continued to occur in up to 1/3 of cases.[ 9 , 10 ]


There are multiple causes for the “errors” resulting in WLS, WSS, and WSSS.[ 1 , 2 , 4 - 7 , 9 , 12 , 14 , 17 - 20 ] The most common cause includes anatomic variants (i.e. transitional levels (sacralized lumbar vertebra/lumbarized sacral vertebra), lumbar ribs, butterfly vertebrae, hemivertebra, block/fused vertebra, spinal dysraphism, Kilppel-Feil vertebrae in the cervical spine, craniovertebral junction variants, cervical ribs, and others).[ 1 , 2 , 4 - 7 , 9 , 12 , 14 , 17 - 20 ] The second most common cause included failure to obtain adequate X-rays/fluoroscopic images (i.e. inadequate number of films, poor quality films/ studies, and their misinterpretation). Multiple other causes of WLS, WSS, and WSSS included; failure to use fixed reference points, operating on tumors, infection, a history of prior surgery, obesity, and osteoporosis. “Human error” was another major contributor to WLS, WSS, and WSSS and was variously attributed to; physicians/staffing fatigue, “rushing”/ emergencies, failure of personnel to “speak up”, failure to communicate/hierarchical operating room culture, and poor surgeon/resident/staff counting techniques.[ 1 , 2 , 4 , 5 , 6 , 8 , 9 , 12 , 14 , 17 - 20 ]


Most series documented a higher incidence of WLS involving the lumbar rather than the cervical spine [ Table 1 ].[ 10 , 14 , 20 ] Mody et al. (2008) observed WLS occurred in 71% of cases in the lumbar, followed by 21% in the cervical, and 8% in the thoracic spine.[ 14 ] Longo et al. (2012) confirmed this observation.[ 10 ] However, Watts et al. (2019), found WLS in 32 cases occurred more frequently in the cervical (14 cases), followed by the lumbar (13 cases), and lastly, the thoracic (5 cases) spine.[ 20 ]


Multiple authors offered general recommendations for avoiding WLS in the spine.[ 4 , 12 , 20 ] Mayer et al. (2014) suggested requiring intraoperative needles be placed either in facet joints, or spinous processes (i.e. into fixed bony structures).[ 12 ] Watts et al. (2019) recommended obtaining better images and requiring more astute radiographic interpretation by operating surgeons.[ 20 ] Devine et al. (2020) further advised repeating intraoperative imaging following the initial spinal exposure to confirm the correct level, while also comparing these studies to the preoperative images.[ 4 ]

Avoidance of WLS with Double Intraoperative X-ray Technique

Patel et al. (2019) recommended that spinal surgeons utilize a double intraoperative X-ray technique to avoid WLS (2010–2017; 1988 posterior lumbar cases).[ 17 ] The first X-ray involved the placement of two needles 3 cm on either side of the midline at the cranial and most caudal levels of the presumed incision. Following the initial operative exposure, the second X-ray was obtained with the confirmatory needle placed in the correct facet joint. With this technique, they observed no instances of WLS, and a reduced 6 patient (0.3%) frequency of WLE/ULS.

Avoidance of WLS Using a Tricple X-ray Method

Other authors used at least 3 intraoperative films to avoid WLS and WLE/ULS [ Table 1 ].[ 3 , 7 ] Irace and Corona (2010) used a three-X-ray method to confirm the correct operative level in 818 patients undergoing lumbar laminectomy/ discectomy (2001–2005).[ 7 ] The X-ray was obtained after placing a wire through the skin (before the skin incision) into the correct spinous process; the surgeon(s) had to verify its location with lateral fluoroscopy. The second step was to obtain oral verification of the correct level by a nurse in the operating room. The third step required at least one additional intraoperative fluoroscopic image for level verification; more studies could be obtained as indicated. With this 3-X-ray method, they observed no instances of WLS, and only one patient had the wrong level initially exposed (i.e. this error was recognized, and corrected with repeat fluoroscopic imaging during the index procedure). Dablouk et al. (2019) utilized a slightly different 3-X-ray method to localize lumbar surgical levels in 301 patents undergoing lumbar laminectomies for stenosis and disc herniations.[ 3 ] The 1st X-ray provided skin localization, the 2nd X-ray was obtained for intial “open” intraoperative localization, and the 3rd X-ray was obtained for final localization at the end of the surgery, prior to closure. They reduced WLS to 0, while WLE/ULS occurred in just 4.3% of cases.

Author’s 3-4 X-ray Technique to Avoid WLS, WSS, WSSS, and WLE/ULS

Epstein’s recommendation to avoid WLS, WSS, WSSS, and WLE/ULS includes a 3–4 X-ray technique, First, the patient is prepared/draped, and the first Time Out is obtained (i.e. using the 3 R’s to confirm the right patient, right procedure, right level/side). Next, a sterile 18-gauge needle is percutaneously introduced into either a spinous process or an interspinous ligament; the first lateral fluoroscopic image is then interpreted/verified both by the operating surgeon and the assistant (i.e. Physician Assistant/Physician, other). This is followed by a 2nd Time Out. After initial exposure of the wound, a clamp is placed either on a spinous process or an interspinous ligament; the 2nd film is verified both by the operating surgeon and assistant. This if followed by a 3rd Time Out. Note, the patient’s films on the board or TV screen must additionally be consulted to verify the correct operative site/level. Subsequently, for a disc herniation a 3rd intraoperative film is typically obtained with a Penfield elevator in the disc space. Alternatively, if a laminectomy has been performed for stenosis, the 3rd X-ray typically requires the placmeent of either a Penfield elevator or dental too at the most cephalad and caudad ends of the operative decompression (i.e. to further confirm operative levels). Notably, if fusions are being performed, there are typically many additional intraoperative fluoroscopic images taken during the course of surgery to confirm the correct level/ placement of instrumentation.


Clarke et al. (2008) cited WSS as largely attributable to the failure to use the 3 R protocol; right patient, right level, right side, plus the failure to appropriately mark the operative site preoperatively.[ 2 ] They also emphasized the need to confirm the operative site by comparing the films obtained intraoperatively with the preoperative MR studies/reports, preoperative X-rays, and operative consent.


Mesfin et al. (2015) asked spinal fellows (i.e. through NASS: North American Spine Society) to participate in a survey regarding WSSS; 46 fellows responded.[ 13 ] Fourteen of the 46 fellows had already experienced WSSS (i.e. a 30.4% incidence), and 79% of the 14 were interested in additional formal training to avoid this “error” in the future. Interestingly, for the 32 who had not yet experienced WSSS, a lesser 44% expressed interest in such training.


There can be significant medicolegal repercussions of WSSS.[ 11 , 14 ] In Mody et al. (2008) questionnaire, (415 neurosurgeons; 12% of the total queried), 50% of spine surgeons had at least 1 case of WLS during their careers.[ 14 ] Further, 73 (13%) patients subjected to WLS experienced permanent disabilities, resulting in legal suits, and or settlements. When Machin et al. (2018) reported on the impact of WSSS in England (i.e. all medicolegal spine cases between 2012 and 2017), they identified 978 spine surgery claims of “clinical negligence” brought against the National Health Service (i.e. against Orthopedists and Neurosurgeons).[ 11 ] The cost over 5 years was 535.5 million pounds; notably, the case number/costs increased over time. “Negligence” was variously attributed to; poor judgement/ imaging failures (52.3%), inadequate interpretation of X-ray studies (26.07%), bad outcomes (19.63%), failure of informed consent (8.13%), and WSSS/retained instruments (2.66%). Data over 3 years resulted in 574 claims of “negligence” due to; iatrogenic nerve damage (15/8%), iatrogenic cord injury (12.54%), and infection (8.89%).


The most typical reasons for WLS, WSS, and WSSS include; unusual anatomical variations, failure to follow level/site/ side verification protocols (i.e. the Universal Protocol, Time Outs, and 3 R’s), and “human error”. Remaining vigilant in recognizing the different factors that contribute to WLS, WSS, and WSSS should reduce their incidence in the future.

Declaration of patient consent

Patient’s consent not required as there are no patients in this study.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


Jamie Baisden, M.D., Professor of Neurosurgery, Medical College of Wisconsin

Milwaukee WI 53226

The rule, measure three times, and cut once, has been an intraoperative standard for my practice. Certainly, junctional anatomy is particularly problematic, and intraoperative X-rays are often suboptimal. Use of oblique fluoroscopy and/or O-arm are helpful in morbidly obese, short necked/wide shouldered patients to prevent wrong level surgery (WLS).

How to Avoid Thoracic WLS By Placing A Coil in the “Correct” Pedicle

WLS is estimated to occur in up to10% of procedures addressing thoracic discs. Use of interventional radiology to place a coil in or near the “correct” pedicle (i.e. including the “correct” side and level of the proposed procedure) has been useful. First, the marking does not wash off like with the preoperative marking pens. Second, the fluoroscopy equipment in the radiology department is typically of better quality than the portable units in the operative suite. Importantly, this additional “procedure” is covered by most insurances and, although more expensive, is very accurate, and may avoid WLS.

Localization Issues with Minimally Invasive Surgery (MIS)

On a smaller scale, minimally invasive surgery has its own set of localization issues (i.e. as with the wanding technique to clear the interlaminar/facet junction). Residual soft tissue and/or a sub-optimally tightened retractors applied during docking may result in slippage. Here, a 1 cm arc at the skin may produce up to a 2–3 level error in the lumbar spine, and even greater level errors in the cervical spine.

Intradural Tumor Resection Utilizing Ultrasound For Site Confirmation

Lastly, for intradural lesions, a quick intraoperative ultrasound after the bony decompression allows for verification that the exposure is adequate while also allowing for level/lesion confirmation.


More thought and intraoperative preparation makes for safer surgery, and the avoidance of WLS, WSS, and WSSS.


Benjamin R. Cohen MD; Adjunct Assistant Professor, Department of Neurology, School of Medicine, NYU Long Island School of Medicine, NY 11501

Dr. Mark Agulnick

Adjunct Associate Professor of Orthopedic Surgery, Department of Orthopedics, NYU Long Island School of Medicine, NY 11501

Two spinal surgeons, one a neurosurgeon and the other an orthopedist, offer the following points regarding how to avoid wrong level (WLS), wrong side (WSS), and wrong site spinal surgery (WSSS). They both emphasized the following major points.

Preoperative planning Get as many plain films as needed Correlate plain films and CT with the preoperative MR Especially on complex cases, those with anticipated vertebral anomalies, or with problematic physiognomy). Preoperatively review the films (X-rays, MR, CT) with the radiologist/neuroradiologist to clarify the pathology and levels Particularly regarding L5-S1 anomalies Do not be afraid to ask the technologist in the operating room to repeat films Do this as many times as needed where the quality and or level are not clear For multilevel cervical and/or lumbar laminectomies The levels requiring decompression should be confirmed by at least 2 participants (i.e. primary surgeon and assistant surgeon/Physician Assistant) There are instances in which the decompression should be continued based on the intraoperative pathology (i.e. extent of stenosis), not just on the preoperative radiographic imaging studies Penfield or Woodson should be placed in a disc space to confirm a level This especially applies to disc/far lateral disc surgery There are multiple localization techniques The BEST way to localize in the lumbar spine is to put the marker in the pedicle The NEXT BEST technique is to put a Kocher on the correct facet The WORST technique is to put a marker on a spinous process Cervical surgery localization (particularly posterior procedures) may be very difficult Especially with lateral mass screws at the C3 or C4 levels, or C6, C7, T1 levels Thoracic Surgery Localization may be uniquely problematic Most patients are on a Jackson table Best Technique: Use AP Fluoroscopy to count ribs for level confirmation Next Best: Put a clamp on a facet Obtain a wide film to see T12 and count up Note: some patients have anomalous rib counts For ELECTIVE Thoracic Surgery Send the patient for preoperative CT localization Inject the skin and interspinous ligament with methylene blue Obtain additional intraoperetive AP fluoroscopic confirmation of the level Before the incision put a spinal needle into the correct facet joint and take a film Open the incision and take another film to confirm/correlate the level Intradural Tumor Localization Confirmation Do all the above maneuvers especially for thoracic tumor localization Before opening the dura, obtain intraoperative ultrasound to confirm the tumor location Spinal Surgical Localization Multiple techniques involve reepated checks and balances Having two surgeons in the operating room where both must agree Will help confirm the correct level and correct side and site of surgery


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