Adrenal diseases, such as adrenal tumors and adrenal hyperplasia, are common and frequently occurring conditions in urological surgery. With the development and widespread use of diagnostic technologies like CT scans, an increasing number of patients are being diagnosed [4]. Most patients with adrenal tumors and some with adrenal hyperplasia require adrenalectomy to alleviate their conditions. Therefore, adrenalectomy has become one of the most common surgeries in urology. The pursuit of minimizing surgical trauma and complications marks a significant trend in the evolution of surgical practices. In the late 20th century, the introduction of laparoscopy revolutionized surgical procedures, ushering in a new era beyond traditional open surgery. Minimally invasive surgery, particularly laparoscopic surgery, has established its superiority, demonstrating promising prospects for the future. With advancements, urological laparoscopic techniques have gained widespread acceptance and application. Retroperitoneoscopic techniques, benefiting from their retroperitoneal approach, offer direct access to the unilateral adrenal gland and urinary system, thus gaining increasing attention for causing less disturbance to intra-abdominal organs, ensuring shorter operation times, and facilitating faster recovery. However, retroperitoneal surgeries present challenges such as relatively smaller operating spaces, less clear anatomical landmarks, and greater operational difficulty, compared to transabdominal laparoscopic surgeries. With the continuous improvement of operators’ technical experience, advancements in surgical instruments, and the adoption of new techniques, retroperitoneoscopic adrenalectomy has demonstrated significant advantages, establishing it as the gold standard for adrenal gland surgery treatment​​ [5, 6], making it one of the most performed urological laparoscopic surgeries both domestically and internationally.

With the widespread implementation of retroperitoneoscopic adrenalectomy, there has been a notable increase in surgical experience. Additionally, a deeper understanding of the anatomy of the retroperitoneal space has also facilitated further refinement of the procedure. Currently, the procedural steps for retroperitoneoscopic adrenalectomy have been largely standardized [2, 8]​​: It begins with creating sufficient retroperitoneal space (using balloon dissection or instrumentation), followed by separating and expanding the retroperitoneal tissues layer by layer, based on internal landmarks. This includes clearing part of the fatty tissue and freeing the upper pole of the kidney, which aids in revealing the target organ (adrenal gland or tumor) for easier laparoscopic visualization and instrument handling. The final step is dissecting along the target organ to complete the surgery. Analyzing the above surgical process from an anatomical perspective, apart from the smaller abdominal incision, the operations within the retroperitoneum are similar to those of open surgery, or it can be said to replicate the procedural steps of open surgery​​ [4,5,6,7,8]. Thus, the trauma caused by retroperitoneoscopic adrenalectomy, compared to traditional open surgery, is similar in terms of internal damage in the retroperitoneum, aside from the smaller abdominal wall incision. However, this approach can lead to corresponding complications and accidental injuries, and the lack of direct tactile feedback for the surgeon may increase the risk of accidental injuries. In recent years, to further reduce surgical trauma and improve cosmetic outcomes, single-port laparoscopic techniques have rapidly developed and emerged as a significant area of clinical research [2]​​. This has even led to the emergence of robotic assistance for single-port laparoscopic surgeries. Single-port retroperitoneoscopic adrenalectomy is also being performed internationally, reducing the abdominal wall incisions from the original 3–4 ports to a single larger port, which has a better cosmetic effect. This type of surgery creates a similar space for separation of tissues in the retroperitoneum as traditional retroperitoneoscopic surgery​​ [2], thus causing similar trauma and complications. Moreover, it requires a larger single port, the total length of which is comparable to the incision in traditional retroperitoneoscopic surgery. To overcome the trauma caused by this surgical approach, it is essential to explore more minimally invasive surgical methods, which will undoubtedly become a new research direction in laparoscopic surgery. According to reports [7, 9, 10]​​, the complication rate of retroperitoneoscopic adrenal surgery is about 10%, with more severe complications occurring at a rate of 2–5.7%. Common complications include peritoneal injury, pleural injury, injury to the central adrenal vein, severe hypercapnia, wound infection, and retroperitoneal hematoma. Additionally, there are several reports of serious complications such as injury to the inferior vena cava, renal vessels, liver, spleen, pancreas, and massive bleeding leading to patient death. All the above complications can occur during the process of separating and locating the adrenal gland or adrenal tumor (the target organ)​​ [2, 8, 9]. Therefore, reducing the complications and accidental injuries in retroperitoneoscopic adrenal surgeries requires more precise operations and technical support, which will continue to be a major focus in clinical research for this surgery.

Reducing trauma and complications in laparoscopic surgery has become a research focus in recent years. This interest has been sparked by the need to improve patient outcomes and minimize post-operative recovery times. Recently, the use of surgical navigation systems and 3D printing technology has emerged as innovative methods to guide surgical procedures, showing good results in avoiding vital organs and reducing accidental injuries [11,12,13]. However, these advances have not improved the steps involved in operating within the retroperitoneum or the extent of tissue separation. Our recently developed “targeted retroperitoneoscopic adrenalectomy” has, through initial clinical application, proven capable of more directly accessing the adrenal gland. With a personalized design of the retroperitoneal approach, it can reduce trauma to the retroperitoneum, enhance surgical safety, and achieve better cosmetic results. However, due to the limitations of the operative equipment and the relative difficulty of the procedure, this technique is more suitable for smaller adrenal adenomas. For larger tumors and pheochromocytomas, which are prone to bleeding, further development is needed, as currently, there is no advantage in terms of operation time.

Our developed “targeted retroperitoneoscopic adrenalectomy” utilizes manual marked navigation to precisely guide a single-port, single-channel retroperitoneoscope directly to the target organ within the retroperitoneum, namely the adrenal gland or its tumor. The successful implementation of the tunnel method retroperitoneoscopic adrenalectomy, after preliminary clinical application, has shown that this technique achieves the experimental design objectives, namely, more direct access to the adrenal gland and other target tissues, effectively reducing separation trauma and related complications.

Intraoperative Precautions:1. Due to the limited operative space, handling complex cases such as larger adrenal tumors or obese patients can be challenging, necessitating additional puncture holes. Pheochromocytomas, which are rich in blood vessels and often adhere to surrounding tissues, can cause significant fluctuations in blood pressure during surgery. Extreme caution is required, and additional puncture holes may be needed when beginning to separate the tumor, with preparations for switching to traditional laparoscopy if necessary. Before the surgery, the patient’s blood pressure and heart rate need to be stabilized, and then the surgery can be scheduled. Moreover, the patient’s recovery after surgery is relatively slow, and the longest hospital stay can be up to 6 days.2. As the direction of the trocar’s puncture slightly differs from that of the puncture needle, and anatomical changes are likely to occur after insufflating the retroperitoneum, the methylene blue artificial markings may be lost after the laparoscope is inserted. Generally, a slight separation in the forward and upward direction under the abdominal wall can help locate the artificial markings. 3. Commercially available methylene blue solutions are too concentrated and should be diluted tenfold to prevent the overly deep color from impairing the operative field of view.