INTRODUCTION
YE in laparoscopy
Yellow enhancement (YE) mode is a novel feature in laparoscopic imaging that facilitates the identification of structures during minimally invasive surgery without requiring patient intervention. YE enhances contrast by causing orange-yellow structures to appear more distinctly yellow. Our findings suggest that in gastrointestinal surgery, YE mode may increase the visibility of blood vessels, nerves, and lymph nodes within fatty tissue, thus assisting in surgical dissection.
YE operates through color conversion, shifting certain colors to yellow to improve contrast. This effect makes fat appear distinctly yellow, while blood vessels and other structures retain their normal appearance. As illustrated in Fig. 1, the images captured by the camera are processed by a yellow-enhancing image processor, which performs the color conversion and produces an altered image. Surgeons can easily toggle this function on and off during surgery. The indications for the use of YE are not yet fully established, as it represents a relatively new technology. A potential indication has been suggested by Dr. Shreeyash Modak [1], who discusses the advantages of YE in delineating pancreatic borders in patients who have obesity and thus exhibit high fatty tissue content around the pancreatic parenchyma. Nonetheless, the benefits of YE in gastrointestinal surgery remain to be established.
The use of YE during high anterior resection in a patient with obesity is demonstrated in Fig. 2. This case allowed us to highlight the benefits and utility of YE in gastrointestinal surgery.
Factors affecting the difficulty of anterior resection in patients with obesity
Laparoscopic high anterior resection with YE was performed for rectosigmoid cancer in a middle-aged Asian man with obesity. The expected operative challenges associated with obesity include the following: (1) reduced visualization due to the difficulty in maneuvering and retracting the bowels because of limited space [2]; (2) an increased risk of intraoperative nerve injury due to compression or traction [2]; and (3) a thickened and shortened mesentery, which restricts access to the bowels and deeper pelvic areas, distorts surgical planes, and heightens the risk of unnecessary bleeding, particularly if dissection occurs in incorrect planes [3]. Additional challenges in these patients include limited instrument reach and heightened anesthesia-related risks due to the extended duration of the operation [4]. Moreover, identifying vessels in patients with increased mesenteric adipose tissue is challenging, which further elevates the risk of intraoperative bleeding.
YE USE IN THE PRESENT CASE
Identification of surgical planes and blunt dissection
In the video, we discuss 3 ways in which YE was beneficial in identifying surgical planes and facilitating blunt dissection. First, YE mode increases contrast, which enhances the distinction between yellow adipose tissue and the avascular plane (visceral vs. parietal peritoneum). This creates a clearer transition zone, enabling more precise dissection. Second, dissection can be performed closer to the bowel wall, conferring surgical advantages, although this also carries a risk of injury to surrounding structures/vessels. Third, YE contributes to a reduced risk of misidentifying surgical planes, which can lead to visceral, vascular, or peritoneal injuries. This risk is heightened in patients with obesity due to thickened mesentery and increased adipose tissue.
Identification of vessels to minimize bleeding
We illustrate the importance of early identification of nonadipose tissue in preventing accidental injury to critical structures, especially in patients with obesity. The video demonstrates the tracing, clipping, and ligation of the inferior mesenteric artery (IMA), a process facilitated by YE. The presence of an excessive amount of adipose tissue around the artery necessitates careful dissection to prevent arterial damage. YE streamlines the dissection process above the IMA, ensuring that only adipose tissue is dissected prior to clipping the artery. Additionally, it improves the visibility of the artery, allowing for precise skeletonization and ligation.
The use of YE could potentially be extended to patients with aberrant vasculature. This issue was highlighted in a case involving intestinal malrotation, which led to variation in the vascular anatomy [5]. A literature review in the same article revealed that laparoscopic resection was performed in only 44.7% of patients with colorectal cancer and intestinal malrotation, due to concerns about vascular anomalies that could interfere with safe resection [5]. Adopting YE may offer benefits for interoperative identification of the vasculature in such patients.
Identification of structures to be spared: nerves and ureters
During high anterior resection, crucial structures must be identified to avoid causing damage. Specifically, the ureter must be located before the IMA is ligated. As discussed in the video, extensive dissection of adipose tissue was required to find the left ureter. The use of YE mode facilitated its identification amidst the surrounding fat. Fig. 3 [1], illustrates the difference in appearance between the ureter and fat tissue with and without the use of YE.
Other key structures that can be easily differentiated using YE include the retroperitoneal hypogastric nerve plexus. In the present case, the hypogastric nerves were identified by blunt dissection of the overlying fascia and fat. The contrast between the hypogastric nerves and the surrounding fat tissue is evident in the video; however, the video does not fully capture the extent of blunt dissection of the fat required to expose the hypogastric nerves. Without the enhancement provided by YE, the blunt dissection and identification of the nerves would be challenging, particularly in patients with higher levels of adiposity around these structures.
DISCUSSION
The indications for YE usage are still being established, and we anticipate that with increased clinical application, additional indications and uses for YE will be identified. Here, we address the use of YE for efficient colorectal surgical management in patients with obesity, specifically cases in which high fat tissue content hinders exposure and complicates the identification of key anatomical structures.
YE mode assists in preventing the misidentification of dissection planes, allowing surgeons to cut closer to the bowel wall while avoiding inadvertent damage to adjacent structures. YE mode highlights the dissection plane, which lies between 2 fat-containing structures—the retroperitoneum and the mesentery—by enhancing the contrast between yellow and white tissues [6]. In patients with obesity, among whom retraction may be more challenging, the dissection line has a narrower safety margin between the retroperitoneal and mesenteric fat. Consequently, the heightened contrast that delineates the white tissue between the 2 layers of yellow fat is crucial, as it reduces the margin for error.
Moreover, YE can reduce surgeon fatigue and assist less experienced surgeons in quickly identifying anatomical planes, thus minimizing the risk of injury. Although not currently utilized for training purposes, YE demonstrates potential for educational applications by enabling a clearer understanding of the avascular plane of dissection between the 2 layers of fat tissue. The enhanced contrast between yellow and white tissues may aid junior surgeons in situations where adequate exposure or retraction may be challenging.
Furthermore, structures that are typically obscured by fat—such as vessels, ureters, and the pancreas—display different contrast relative to the fat, making them easier to identify for both junior surgeons and fatigued senior surgeons. This enhancement could aid in navigating variable anatomies and may also facilitate the intraoperative identification of aberrant blood vessels.
In the present case, YE was particularly beneficial due to the large amount of adipose tissue that obscured various anatomical structures. The enhancement of fat tissue allowed these structures to become more visible and distinguishable from the surrounding adipose tissue.
Other advantages of YE include the ease with which the surgeon can toggle the function on and off, alternating between white light and yellow-enhanced images. This feature is particularly beneficial in mitigating a potential drawback: visual fatigue resulting from prolonged exposure. Research has indicated that extended exposure to warm fluorescent lighting can be associated with visual fatigue [7, 8], raising concerns that YE might have a similar effect. Additionally, senior surgeons may resist the adoption of YE if they find it challenging to adapt to initially.
CONCLUSION
The use of YE markedly improves the identification of surgical planes and critical structures during laparoscopic colorectal surgery in patients with obesity. This enhancement not only increases surgical precision but also helps to reduce surgeon fatigue. Additionally, its utility may extend to the intraoperative identification of aberrant blood vessels or anatomical variations.
ARTICLE INFORMATION
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Conflict of interest
Frederick H. Koh is an editorial board member of this journal, but was not involved in the peer reviewer selection, evaluation, or decision process of this article. No other potential conflict of interest relevant to this article was reported.
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Funding
None.
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Acknowledgments
The authors thank the patient for providing written informed consent for publication of her clinical information and video.
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Author contributions
Conceptualization: FHK, HS; Investigation: RS, HS; Methodology: HS; Project administration: FHK, HS; Visualization: HS; Writing–original draft: HS; Writing–review & editing: all authors. All authors read and approved the final manuscript.
Supplementary materials
Supplementary Video 1.
Yellow enhancement imaging facilitates identification of surgical planes and key structures during challenging high anterior resection in a patient with obesity.
Supplementary materials are available from https://doi.org/10.3393/ac.2024.00465.0066.
Fig. 1.Process of conversion to yellow enhancement (YE) and difference in laparoscopic image output. Surgical images are from our case. WLI, white light imaging; LED, light-emitting diode; RGB, red, green, and blue; IR, infrared. Diagram courtesy of Olympus Corp.
Fig. 2.Comparison of white light imaging (WLI) mode with yellow enhancement (YE) mode. Image courtesy of Olympus Corporation.
Fig. 3.Ureter (A) with and (B) without yellow enhancement. Image courtesy of AIG Hospitals [1].
REFERENCES
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