2.8. Clouding of the Operative Field
@ProfFishchenkoPrevious section: Creating the Working Space
If visibility deteriorates during BESS/UBE, I stop manipulating and determine the cause. I first check the endoscope optics, irrigation fluid inflow and free outflow, and the presence of bleeding.
Contamination and damage to the optics
When learning the technique, it is particularly important to avoid contact between the rotating burr and the endoscope optics. If the image deteriorates, I check the cleanliness of the outer lens surface and the integrity of the optical system. Sometimes the image is clear at the start of surgery but gradually becomes cloudy.
If cleaning does not restore the image or there are signs of damage, I replace the endoscope optics.
Insufficient irrigation fluid outflow
I check fluid inflow and free outflow through the working portal, including whether the outflow path is obstructed by an instrument or soft tissue. I use the minimum sufficient irrigation pressure and do not compensate for impaired outflow by increasing pressure.
Insufficient muscle relaxation
Insufficient muscle relaxation may allow the paraspinal muscles to compress the working portal and impede outflow. If I suspect this mechanism, I discuss the adequacy of muscle relaxation with the anesthesiologist, taking the chosen anesthetic technique into account.
Bleeding
Blood in the irrigation fluid impairs visibility, particularly when the working space is insufficiently flushed. I assess the presence of bleeding and the need for hemostasis.
Obstruction of the view by epidural fat
During endoscopic lumbar discectomy, epidural fat is preserved unless it obstructs the view. If mobile portions of fat moving in the irrigation flow obscure the operative field, only the tissue interfering with visualization is removed under direct endoscopic control [6].
Checks before resuming work
I do not continue resection or activate the RF electrode blindly. I first restore visibility of the instrument and anatomical landmarks.
References
1. Lewandrowski KU, Tieber F, Hellinger S, et al. Durability of Endoscopes Used During Routine Lumbar Endoscopy: An Analysis of Use Patterns, Common Failure Modes, Impact on Patient Care, and Contingency Plans. Int J Spine Surg. 2021;15(6):1147–1160. DOI: 10.14444/8146. PubMed.
2. Choi DJ, Choi CM, Jung JT, Lee SJ, Kim YS. Learning Curve Associated with Complications in Biportal Endoscopic Spinal Surgery: Challenges and Strategies. Asian Spine J. 2016;10(4):624–629. DOI: 10.4184/asj.2016.10.4.624. PubMed.
3. Hong YH, Kim SK, Hwang J, Eum JH, Heo DH, Suh DW, Lee SC. Water Dynamics in Unilateral Biportal Endoscopic Spine Surgery and Its Related Factors: An In Vivo Proportional Regression and Proficiency-Matched Study. World Neurosurg. 2021;149:e836–e843. DOI: 10.1016/j.wneu.2021.01.086. PubMed.
4. Kang T, Park SY, Lee SH, Park JH, Suh SW. Assessing changes in cervical epidural pressure during biportal endoscopic lumbar discectomy. J Neurosurg Spine. 2021;34(2):196–202. DOI: 10.3171/2020.6.SPINE20586. PubMed.
5. Merter A, Özyıldıran M, Kurt F, Özçelik M. Bispectral Index Monitoring in Endoscopic Lumbar Spine Surgery: Retrospective Analysis of Central Nervous System Complications. World Neurosurg. 2025;200:124230. DOI: 10.1016/j.wneu.2025.124230. PubMed.
6. Lee N., Heo D.H., Park C.K. Biportal Endoscopic Approach (Biportal Endoscopic Lumbar Discectomy). In: Advanced Techniques of Endoscopic Lumbar Spine Surgery. Springer; 2020. P. 123–136; relevant passage: pp. 127–128.