Strategies to avoid wrong-site surgery during spinal procedures

A Novel Marking Technique for Accurate Minimal Invasive Approaches in Spine Tumor Surgeries With Activated Carbon Marking

BACKGROUND AND OBJECTIVES

To describe a novel, practical, reproducible, and effective preoperative marking technique for accurate localization of the spinal level in a series of patients with tumor lesions.

METHODS

We retrospectively analyzed patients undergoing minimally invasive (MIS) surgery for spine tumors from 2016 to 2021, in which this marking technique was used. Twenty-one patients, with tumor lesions involving difficult radioscopic visualization (cervicothoracic junction or upper dorsal spine, C6-T8), were included. Tumor lesion level was previously determined with enhanced MRI in all cases. Twenty-four to forty-eight hours before surgery, computed tomography image-guided carbon marking was performed by administration of aqueous suspension of carbon with a 21-gauge needle placed resembling the MIS approach planned trajectory. During surgery, activated carbon marking was followed until reaching the final target on the bone. Next, sequential dilators and an MIS retractor were placed. Then, bone resection and tumor exeresis were performed according to the case.

RESULTS

Average age was 60.6 years (26-76 years). Fifteen (71%) patients were women. In most cases (76%), tumor pathology involved intradural lesions (meningiomas and schwannomas). In all cases, the marking described allowed to accurately guide the MIS approach to tumor site. Neither intraoperative fluoroscopy nor approach enlargement was required in any procedure. Postoperative complications were reported in only 4 patients, none related with the marking.

CONCLUSION

Computed tomography image-guided activated carbon marking allows to accurately lead MIS approaches in a practical, reproducible, and effective way in cases of tumors localized in regions of the spine of difficult radioscopic visualization.

Preoperative coil localization for spinal surgery is accurate, safe and effective: a single-centre initial experience

OBJECTIVE AND STUDY DESIGN

This is a retrospective, descriptive study of consecutive patients undergoing novel preoperative pushable coil localization for spinal surgery, in order to evaluate its feasibility, safety and accuracy.

METHODS

Consecutive patients who underwent pre-operative coil marking for spinal surgery at our institution from May 2018 to July 2021 were included. Data were collected for coil placement, accuracy, complications and fluoroscopy usage. Patient demographic and relevant perioperative and procedural data were also collected.

RESULTS

A total of 34 patients were identified of which 32 (94%) had complete data and imaging at last clinical follow up, with a mean duration of 13.9 months. There were no incorrect level surgeries performed. There were no coil-related complications found in our cohort.

CONCLUSIONS

Preoperative coil placement is an accurate, safe and well-tolerated method for level localization in spinal surgeries.

Variations in the Number of Vertebrae, Prevalence of Lumbosacral Transitional Vertebra and Prevalence of Cervical Rib Among Surgical Patients With Adolescent Idiopathic Scoliosis: An Analysis of 998 Radiographs

STUDY DESIGN

Retrospective Study.

OBJECTIVE

This study aims to investigate variation in the number of thoracic and lumbar vertebrae, the prevalence of lumbosacral transitional vertebra (LSTV) and the prevalence of cervical ribs among surgical patients with adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Due to variation in the number of thoracic or lumbar vertebrae, inaccurate identification of vertebral levels has been found to be a contributory factor to wrong-level surgery.

METHODS

This was a retrospective study on AIS patients who underwent posterior spinal fusion. Demographic and anthropometric data (age, gender, height, weight, and body mass index), radiographic data (Lenke curve type, pre-operative Cobb angle, vertebra numbering of cervical, thoracic, and lumbar spine, presence of LSTV based on the Castellvi classification and the presence of cervical ribs) and clinical data were collected. Data were analysed and reported with mean and standard deviation for quantitative parameters and number and percentage for qualitative parameters. Multinomial logistic regression analyses were performed to identify factors associated with the outcomes of interest.

RESULTS

A total of 998 patients met inclusion criteria, of which 135 (13.5%) were males and 863 (86.5%) were females. The vertebrae number varied between 23 to 25 total vertebrae with 24 vertebrae considered as the typical number of vertebrae. The prevalence of atypical number of vertebrae (23 or 25) was 9.8% (98 patients). We found a total of 7 different variations in number of cervical, thoracic, and lumbar vertebrae (7C11T5L, 7C12T4L, 7C11T6L, 7C12T5L, 7C13T4L, 7C12T6L, and 7C13T5L) with 7C12T5L considered as the typical vertebrae variation. The total prevalence of patients with atypical vertebrae variation was 15.5% (155 patients). Cervical ribs were found in 2 (0.2%) patients while LSTV were found in 250 (25.1%) of patients. The odds of 13 thoracic vertebrae were higher in males (OR 5.17; 95% CI: 1.25, 21.39) and the odds of 6 lumbar vertebrae were higher in LSTV (OR 3.93; 95% CI: 2.58, 6.00).

CONCLUSION

In this series, we identified a total of 7 different variations in the number of cervical, thoracic, and lumbar vertebrae. The total prevalence of patients with atypical vertebrae variation was 15.5%. LSTV was found in 25.1% of the cohort. It is important to ascertain atypical vertebrae variations rather than the absolute number of vertebrae because variants such as 7C11T6L and 7C13T4L may still have typical numbers of vertebrae in total. However, due to the differences in the number of morphologically thoracic and lumbar vetrebrae, there may still be a risk of inaccurate identification.

Wrong site spine surgery in the U.K.: a review of current practice

Wrong site spine surgery is a rare but serious complication. The scale of the problem in the U.K. and the current practice of spine surgeons in localising the level whilst performing routine spine surgery is unknown. As these events are rare and their nature very disparate, it is necessary to identify whether there are any common themes to be able to take effective steps to mitigate this risk. A review was undertaken of the wrong site spine surgery incidents submitted to StEIS (Strategic Executive Information System), the system used to report and monitor the progress of Serious Incident investigations across the NHS. Subsequently a survey of the Society of British Neurosurgeons was undertaken to answer some of the questions which arose from this review. Up to half of spine surgeons surveyed by the SBNS admit to having performed wrong site spine surgery. 40 percent of wrong site surgery reported to NHSE was at the L4/5 level. What exactly constitutes wrong level spine surgery is not universally accepted by spine surgeons. The critical factors in causing wrong site spine surgery in the U.K. are explored. It is hoped that the results from this study would improve training, lead to better policies and support investment in trying to reduce this complication.

A Contemporary Analysis of Closed Claims Related to Wrong-Site Surgery

BACKGROUND

Wrong-site surgeries are considered "never events" and continue to occur despite the implementation of the Universal Protocol by The Joint Commission in 2003.

METHODS

The authors reviewed closed claims data on wrong-site surgery between 2013 and 2020 from a medical malpractice company. The claims were classified by allegations made by claimants, the responsible services, the types of procedures, the injuries, and contributing factors. Researchers performed a descriptive analysis of the available variables and reviewed the clinical summary of each case.

RESULTS

Between 2013 and 2020, there were 68 wrong-site closed claims cases. The mean age of the patients was 55.7 (standard deviation 16.21) years, and 51.5% were female. The services most frequently responsible for these were Orthopedic (35.3%), Neurosurgery (22.1%), and Urology (8.8%). The most common types of procedures were spine and intervertebral disc surgery (22.1%), arthroscopy (14.7%), and surgery on muscles/tendons (11.8%). The severity of claims was higher in the inpatient setting compared to the ambulatory setting. The most common alleged injuries included the need for additional surgery (45.6%), pain (33.8%), mobility dysfunction (10.3%), worsened injury (8.8%), death (7.4%), and total loss (7.4%). The top contributing factors to wrong-site surgery were failure to follow policy/protocol (83.8%) and failure to review the medical records (41.2%). The mean closed claim value was $136,452.84, and 60.3% of cases were settled.

CONCLUSION

The risk of wrong-site surgeries is increased with spine surgeries, likely due to unique technical challenges. Further research is required to identify effective methods of prevention of these events.

Neurosurgical Wrong Surgical Site in Lower-Middle- or Low-Income Countries (LMICs): A Survey Study

BACKGROUND

One of the most preventable errors of a surgeon's career is operating on the incorrect surgical site (ICSS). No study in any specialty has ever investigated the incidence of ICSS events in lower-income countries. This study focuses on identifying the occurrence of these events along with an analysis of potential causes leading to these unfortunate events.

METHODS

The authors distributed a survey to neurosurgical colleagues from around the world. These surgeons were first asked to identify details about their practice and incidence and personal experience with ICSS in their own careers. At the end of the survey, they responded to questions about their knowledge of safety checklists.

RESULTS

In this study there was a 63.4% response rate. When combined with those who participated through various social media platforms, there were 178 responses. The incidence rate for every 10,000 cases performed was found to be 22.8 in the cranial group, 88.6 in the cervical group, and 158.8 in the lumbar procedural group. This study identified that 40% of participants had never learned or experienced the ABCD time-out strategy and that 60% of surgeons did not use intraoperative navigation or imaging in their practices. The error has never been disclosed to the patient in 48% of the ICSS cases.

CONCLUSIONS

Due to a lack of application of safety checklist protocol, there is an increased occurrence of ICSS events in lower-income countries. The results of this study demonstrate the necessity of investing time and resources dedicated to avoiding preventable errors.

Dural leakage due to ipsilateral needle placement for spinal level localization in unilateral decompression surgery: A case report

Background:

A spinal dural defect caused by needle placement for spinal level localization is an uncommon complication of cerebrospinal fluid leak with the potential for the development of intracranial hypertension.

Case Description:

Our 48-year-old patient underwent unilateral fenestration and sequestrectomy for intractable L5 radiculopathy due to disc herniation at the level L4–5 on the right side. The spinal level was identified with fluoroscopy after placement of a 24-gauge Sprotte spinal needle on the right side. Intraoperatively, a sub-millimeter spinal dural defect was visualized on the ipsilateral side.

Conclusion:

Caution is needed when needle placement is used to localize the spinal level for unilateral surgery.

Variations in the Number of Thoracic and Lumbar Vertebrae in Patients With Adolescent Idiopathic Scoliosis: A Retrospective, Observational Study

BACKGROUND

Abnormal anatomy is a contributory factor to wrong-level surgery. Variations in the number of vertebrae in populations from different races and geographical regions have been described. A ∼10% prevalence of variations in number of thoracic and lumbar vertebrae in adolescent idiopathic scoliosis (AIS) patients has been previously reported. The objectives of present study were (i) to find out the prevalence of variations in the number of thoracic and lumbar vertebrae and the presence of lumbosacral transitional vertebrae (LSTV) in Indian AIS patients and (ii) to correlate these variations with gender and type of curve.

METHODS

Hospital records and imaging of 198 AIS patients were reviewed retrospectively. A standardized numbering strategy was used to identify the number of thoracic vertebrae, number of lumbar vertebrae, and presence of LSTV. Patients' gender and curve type were correlated with the presence of an abnormal number of thoracic or lumbar vertebrae. Radiology reports and operation notes were reviewed to find out instances when the radiologist or surgeon had identified an abnormal number of vertebrae.

RESULTS

Forty patients (20.2%) with abnormally numbered thoracic or lumbar vertebrae were identified. Twenty patients (10.1%) had abnormally numbered thoracic vertebrae, and 33 patients (16.7%) had abnormally numbered lumbar vertebrae. The prevalence of LSTV was 18.2%. Presence of variations did not correlate with gender or curve type. Radiology reports identified 2/40 patients with variations, whereas operation notes showed 4/40 patients had been correctly identified to have abnormally numbered vertebrae.

CONCLUSIONS

There is high prevalence of variation in the number of thoracic or lumbar vertebrae in AIS patients, with most of those missed being identified by radiologists or surgeons. The patient's preoperative imaging must be scrutinized to identify these patients and take the variation into account to avoid wrong selection of fusion levels.

LEVEL OF EVIDENCE

3.

CLINICAL RELEVANCE

Text. The study raises awareness about possibility of wrong selection in fusion levels due to anatomical variations in surgery for AIS.

The Application of O-arm and Navigation System in Precise Localization of Spinal Cord lesions: a Case Series study

OBJECTIVE

To study on the clinical efficacy of precise localization of O-arm and navigation system in spinal cord lesions.

METHODS

From Augst 2015 to September 2019, 22 patients with spinal cord lesions were arranged in the group.The intraoperative cross-sectional images were acquired by O-arm image system, which were transferred to the Stealth navigation system, and fused with pre-opreative MRI images. The image fusion was completed by the Medtronic Synergy Cranial software. The fused images were used to locate spinal cord lesions, assisted by the navigation system. The navigation errors were evaluated by measuring the maximum distance between the end of the lesion in MRI and its real position.

RESULTS

The image fusion were completed in all patients, and we successfully completed the image-guided surgeries of the spinal cord lesions. The time of image processing was between 7 min and 19 min, and the mean value was 15.1 ± 2.2 min. The navigation error was between 0.9 mm and 5.3 mm, the mean value was 1.6 ± 0.9 mm.

CONCLUSION

The application of precise localization of O-arm and navigation system in spinal cord lesions is clinically reliable and feasible.

Building Consensus: Development of Best Practice Guidelines on Wrong Level Surgery in Spinal Deformity

STUDY DESIGN

Consensus-building using the Delphi and nominal group technique.

OBJECTIVE

To establish best practice guidelines using formal techniques of consensus building among a group of experienced spinal deformity surgeons to avert wrong-level spinal deformity surgery.

SUMMARY OF BACKGROUND DATA

Numerous previous studies have demonstrated that wrong-level spinal deformity occurs at a substantial rate, with more than half of all spine surgeons reporting direct or indirect experience operating on the wrong levels. Nevertheless, currently, guidelines to avert wrong-level spinal deformity surgery have not been developed.

METHODS

The Delphi process and nominal group technique were used to formally derive consensus among 16 fellowship-trained spine surgeons. Surgeons were surveyed for current practices, presented with the results of a systematic review, and asked to vote anonymously for or against item inclusion during three iterative rounds. Agreement of 80% or higher was considered consensus. Items near consensus (70% to 80% agreement) were probed in detail using the nominal group technique in a facilitated group meeting.

RESULTS

Participants had a mean of 13.4 years of practice (range: 2-32 years) and 103.1 (range: 50-250) annual spinal deformity surgeries, with a combined total of 24,200 procedures. Consensus was reached for the creation of best practice guidelines (BPGs) consisting of 17 interventions to avert wrong-level surgery. A final checklist consisting of preoperative and intraoperative methods, including standardized vertebral-level counting and optimal imaging criteria, was supported by 100% of participants.

CONCLUSION

We developed consensus-based best practice guidelines for the prevention of wrong-vertebral-level surgery. This can serve as a tool to reduce the variability in preoperative and intraoperative practices and guide research regarding the effectiveness of such interventions on the incidence of wrong-level surgery.

LEVEL OF EVIDENCE

Level V.

Application of Multimodal Image Fusion to Precisely Localize Small Intramedullary Spinal Cord Tumors

OBJECTIVE

We sought to study the application of precise intraoperative localization of small intramedullary spinal cord tumors.

METHODS

From November 2015 to August 2017, 5 patients with small intramedullary spinal cord tumors were arranged in this group. By using the O-arm image system, we acquired the intraoperative computed tomography images of all patients and sent them to the Stealth navigation system. Medtronic Synergy Cranial software was used to complete the image fusion with preoperative magnetic resonance images, and the fused images were used to localize the intramedullary spinal cord tumors by the navigation system. The navigation errors were evaluated by measuring the maximum distance between the end of the tumor in sagittal magnetic resonance imaging and its real position.

RESULTS

Five patients accomplished the multimodal image fusion, and we successfully completed the image-guided surgeries. The mean diameter of tumors was 12.2 ± 3.1 mm in sagittal magnetic resonance imaging, and the mean incision length was 12.7 ± 3.3 mm. The time of image processing was between 13 minutes and 17 minutes, and the mean value was 15 ± 1.6 minutes. The navigation error was between 0.9 mm and 1.5 mm, and the mean value was 1.2 ± 0.2 mm.

CONCLUSIONS

The application of the multimodal image fusion combined with intraoperative O-arm image navigation system can be used to localize small intramedullary tumors.

Adverse events in neurosurgery and their relationship to quality improvement

Adverse events are common in neurosurgery. Their reporting is inconsistent and widely variable due to nonuniform definitions, data collection mechanisms, and retrospective data collection. Historically, neurosurgery has lagged behind general and cardiac surgical fields in the creation of multi-institutional prospective databases allowing for benchmarking and accurate adverse event/outcomes measurement, the bedrock of evidence used to guide quality improvement initiatives. The National Neurosurgery Quality and Outcomes Database has begun to address this issue by collecting prospective, multi-institutional outcomes data in neurosurgical patients. Once reliable outcomes exist, various targeted quality improvement strategies may be used to reduce adverse events and improve outcomes.

Radiograms Obtained during Anterior Cervical Decompression and Fusion Can Mislead Surgeons into Performing Surgery at the Wrong Level

A 68-year-old woman who suffered from C5 nerve palsy because of a C4-5 disc herniation was referred to our hospital. We conducted anterior cervical decompression and fusion (ACDF) at the C4-5 level. An intraoperative radiogram obtained after exposure of the vertebrae showed that the level at which we were going to perform surgery was exactly at the C4-5 level. After bone grafting and temporary plating, another radiogram was obtained to verify the correct placement of the plate and screws, and it appeared to show that the plate bridged the C5 and C6 vertebrae at the incorrect level. The surgeon was astonished and was about to begin decompression of the upper level. However, carefully double-checking the level with a C-arm image intensifier before additional decompression verified that the surgery was conducted correctly at C4-5. Cautiously double-checking the level of surgery with a C-arm image intensifier is recommended when intraoperative radiograms suggest surgery at the wrong level.

Analysis of the techniques for thoracic- and lumbar-level localization during posterior spine surgery and the occurrence of wrong-level surgery: results from a national survey

BACKGROUND CONTEXT

Despite the frequency with which surgeons perform posterior spinal surgery and the precautions against wrong-site surgery, operations on incorrect levels still occur. Wrong-level exposure is documented in 0.32% to 15% of cases. Additionally, there is little consensus as to what is the most accurate method for localizing the correct spinal level.

PURPOSE

The purpose of this study is to investigate the most commonly used localization methods and their association with wrong-level surgery, to determine the prevalence of wrong-level localization, and to identify circumstances commonly associated with wrong-level surgery, and to offer recommendations that may reduce the incidence of these errors.

STUDY DESIGN/SETTING

This was an online survey study that was distributed to North American Spine Society (NASS) members (including both orthopedic surgeons and neurosurgeons). The survey was sent as a Web link within an e-mail.

PATIENT SAMPLE

A total of 2,338 surgeons received the survey, 532 opened the survey, and 173 completed it (7.4% response rate). The survey was only sent once, as recommended by NASS. Of those that responded, 72% (124 of 173) were orthopedic surgeons, 28% (49 of 173) were neurosurgeons, and 73% (126 of 173) were spine fellowship trained.

OUTCOME MEASURES

We sought to investigate self-reported localization methods that are most commonly used (both anatomic landmarks and imaging techniques), the prevalence of wrong-level surgery, and any correlations between localization method and wrong-level surgery.

METHODS

An eight-question anonymous survey was distributed to members of NASS, including orthopedic surgeons and neurosurgeons. There was no pilot testing or validation performed for this survey. The survey was sent as a Web link within an e-mail. Some questions asked surgeons to select as many responses as applicable, and others allowed surgeons to describe in detail any cases of wrong-level surgery. This study neither requires nor receives funding; additionally, no conflicts of interests were reported.

RESULTS

Fluoroscopy was the most commonly used imaging technique for thoracic and lumbar surgeries (89% and 86%, respectively), followed by plain radiographs (54% and 58%, respectively). Surgeons were allowed to select as many responses as applicable, and 76 surgeons reported using both plain radiographs and fluoroscopy. The facet joint with corresponding pedicle was the most commonly used anatomic landmark for localization of thoracic and lumbar surgeries (67% and 59%, respectively), followed by the spinous process (49% and 52%, respectively). Sixty-eight percent of surgeons admitted to wrong-level localization, some of which were rectified intraoperatively, during their careers. Fifty-six percent of these surgeons reported using plain radiographs and 44% used fluoroscopy when the errors occurred. Common sources of preoperative errors included failure to visualize known reference points, recognize unconventional spinal anatomy, and adequately visualize the level because of large body habitus. Common sources of intraoperative errors included poor communication, failure to relocalize after exposure, and poor counting methods.

CONCLUSIONS

Despite the variety of localization modalities, most surgeons use only a few. Whereas wrong-level localization is relatively rare, the ideal frequency is never. There is no standard approach that will entirely eliminate these mistakes; however, using a localization time out and increasing awareness of common sources of error may help decrease the incidence of wrong-level spine surgery.

Primary dural repair in minimally invasive spine surgery

We describe an effective surgical technique in primary repair of the spinal dura during minimally invasive spine surgery (MISS). Objective. Minimally invasive spine surgery includes the treatment of intradural lesions, and proper closure of the dura is necessary. However, primary dural closure can be difficult due to the restricted space of MIS retractors and the availability of appropriate surgical instrumentation. Methods. We describe the use of a needle already used in the pediatric neurosurgical arena that can facilitate easier and safer closure of spinal dura through MISS retractors in two illustrative intradural cases. Results and Discussion. The primary dural closure technique is described and patient demographics are included. The instruments specifically used for the intradural closure through MIS retractor systems include (1) 4-0 Surgilon braided nylon (Covidien, Dublin, Ireland) with a CV-20 taper 1/2 circle, 10 mm diameter needle; (2) Scanlan (Saint Paul, MN, USA) dura closure set. Conclusion. Successful primary dural repair can be performed on primary and incidental durotomies during minimally invasive spinal surgery. We describe the novel use of a 10 mm diameter needle to help surgeons safely and efficiently close the dura with more ease than previously described.

Ten percent of patients with adolescent idiopathic scoliosis have variations in the number of thoracic or lumbar vertebrae

BACKGROUND

Surveys have demonstrated that wrong-site surgery of the spine is performed by up to 50% of spine surgeons over the course of a career. Inaccurate identification of appropriate vertebral levels is a common reason for wrong-site spine surgery. The present study examined the prevalence of variations in the number of vertebrae in patients with adolescent idiopathic scoliosis.

METHODS

A retrospective review of radiographs and reports of 364 consecutive patients undergoing operative treatment for adolescent idiopathic scoliosis at a single center was performed. The study included eighty-eight male patients (24%) and 276 female patients (76%) with a mean age of fourteen years (range, ten to twenty years). Radiographs were reviewed to assess the number of thoracic and lumbar vertebrae and the presence of a lumbosacral transitional vertebra.

RESULTS

Ten percent of the patients (thirty-eight) had an atypical number of vertebrae in the thoracic and/or lumbar spine. Twenty-one patients (5.8%) had an atypical number of thoracic vertebrae, with fourteen having eleven thoracic vertebrae and seven patients having thirteen. Twenty-four patients (6.6%) had an atypical number of lumbar vertebrae, with four having four lumbar vertebrae and twenty patients having six. A lumbosacral transitional vertebra was present in 6.3% (twenty-three) of the patients. Multilevel vertebral anomalies were present in 1.9% of the patients (seven of 364). A variation in the number of vertebrae had been identified in 0.5% (two) of the reports by the radiologist.

CONCLUSIONS

Variations in the number of thoracic or lumbar vertebrae were found in 10% of patients with adolescent idiopathic scoliosis but had been identified in only 0.5% of the radiology reports.

Incidence of Neurosurgical Wrong-Site Surgery Before and After Implementation of the Universal Protocol

BACKGROUND:

Although exceedingly rare, wrong-site surgery (WSS) remains a persistent problem in the United States. The incidence is thought to be 2 to 3 per 10 000 craniotomies and about 6 to 14 per 10 000 spine surgeries. In July 2004, the Joint Commission mandated the Universal Protocol (UP) for all accredited hospitals.

OBJECTIVE:

To assess the effect of UP implementation on the incidence of neurosurgical WSS at the University of Illinois College of Medicine at Peoria/Illinois Neurological Institute.

METHODS:

The Morbidity and Mortality Database in the Department of Neurosurgery was reviewed to identify all recorded cases of WSS since 1999. This was compared with the total operative load (excluding endovascular procedures) of all attending neurosurgeons to determine the incidence of overall WSS. A comparison was then made between the incidences before and after UP implementation.

RESULTS:

Fifteen WSS events were found with an overall incidence of 0.07% and Poisson 95% confidence interval of 8.4 to 25. All but one of these were wrong-level spine surgeries (14/15). There was only 1 recorded case of wrong-side surgery and this occurred after implementation of the UP. A statistically greater number of WSS events occurred before (n = 12) in comparison with after (n = 3) UP implementation (P < .001).

CONCLUSION:

A statistically significant reduction in overall WSS was seen after implementation of the UP. This reduction can be attributed to less frequent wrong-level spine surgery. There was no case of wrong procedure or patient surgery and the 1 case of wrong-side surgery occurred after UP implementation.