Near infrared ray-guided partial cystectomy using da Vinci Firefly® technology and intraoperative cystoscopy for urachal cyst, suspected of urachal tumor.

The urachus is an early embryonic structure, which is obliterated before birth. After the urachus obliterates, it presents as the median umbilical ligament. Normally, this structure appears as a fibrous cord; however, urachal abnormalities such as a patent urachus, umbilical urachal sinus, urachal cyst and vesicourachal diverticulum may occur depending on the location of the originally tubular urachus. While such anomalies are rare, when symptomatic they can cause significant morbidity, and if not appropriately treated with wide resection can harbour the potential for malignant transformation [ 1 ]. Recently, robot-assisted laparoscopic approaches to urachal excision have been described and offered the benefit of a minimally invasive approach to complete urachal excision and technically facilitate bladder closure [ 2 ]. Firefly ® mode is an integrated imaging system in the da Vinci, which can visualize near infrared ray (NIR) as a green color. NIR can penetrate biological tissues deeper than visible light [ 3 ]. Herein, we performed near infrared ray-guided surgery (NIRGS) to identify the tumor location accurately using intraoperative cystoscopy and the da Vinci Firefly ® technology.

The total operative time was 332 minutes and console time of urology part was 75 minutes ( Table 1 ). Estimated blood loss was 50 mL. On pathology, diagnosis of the specimen was confirmed as a urachal cyst with no evidence of malignancy. There was no residual tumor at the resected margin. The cyst wall was lined with GATA3-positive urothelial cells formed a ductal structure ( Fig. 3 ). The patient had an uneventful postoperative course. Her Foley catheter was removed on day 14. At the four-month follow-up, the patient was voiding well. Surveillance cystograms showed a well-healed bladder at eight-month follow-up. She has remained symptom free over the past 18 months since surgery.

The urachus is an embryological structure that connects the allantois to the fetal urinary bladder. Then, the urachus normally obliterates, forming the median umbilical ligament, which lies between the transversalis fascia and the peritoneum. Sometimes, this regression may be incomplete, and the urachal remnant may remain until adulthood. The reported incidence of urachal anomalies in the literature varies, ranging from 1 in 5,000 to 1 in 3 adults with asymptomatic, clinically insignificant remnants at autopsy [ 4 ]. Although surgical resection of symptomatic lesions is generally advocated, management of incidentally found remnants is less clear. Complete excisions of the urachal remnant should be considered in adults who are good surgical candidates because malignant transformation of the remnant is possible [ 1 5 ]. Certain factors may increase this risk, including chronic inflammation and recurrent infections, which predispose urachal remnants to malignant changes due to prolonged irritation of epithelial-lined structures [ 4 ]. Ashley et al. [ 6 ] reported the increased risk of malignancy of a cystic urachal mass with increasing age. In their study, 20% of patients with urachal cancer presented with metastatic disease. Therefore, early surgical treatment should be considered for aged patients with urachal diseases [ 7 ]. Traditional management of urachal cysts includes radical excision of all urachal remnants with or without a cuff of bladder tissue. There have been several case reports of laparoscopic excision of various types of urachal remnants in patients of various ages [ 8 9 ]. Recently, Madeb et al. [ 2 ] described the use of robot-assisted laparoscopic partial cystectomy for the management of urachal anomalies. They listed a number of advantages that were associated with the use of a robot including the ability to visualize the region of interest in a three-dimensional fashion, improved dexterity, excellent ergonomics, and minimal difficulty in performing intracorporeal suturing. The disadvantages of a robotic system are its relatively high cost, limited availability, lack of tactile feedback, a steep learning curve for surgeons, additional operation time for the docking procedure, and additional port placement compared with conventional laparoscopic partial cystectomy [ 10 ]. Addressing these factors is essential for developing a balanced perspective on the widespread adoption of robot-assisted techniques [ 4 ]. In performing partial cystectomy, making an incision with adequate surgical margins and minimizing the normal bladder excision is important for oncologic and functional outcomes [ 11 ]. However, identification of the exact location of the tumor during laparoscopy may be difficult from outside the bladder because the laparoscopist is unable to palpate the lesion during the operation [ 9 ]. As a result, different methods such as ultrasound guidance, cystoscopic tattooing, frozen section analysis (FSA), indocyanine green (ICG) instillation and endoscopic transillumination have been introduced to overcome identification challenges. Intraoperative ultrasound guidance is commonly utilized during urological surgery, especially partial nephrectomy. The use of intraoperative real-time transrectal ultrasound guidance was also reported to be helpful for partial cystectomy in patients whose tumors were lodged within a paraureteral diverticulum [ 12 ]. However, identification of the small or flat lesions is difficult on ultrasound guidance [ 13 ]. Cystoscopic tattooing of bladder lesion margins with a dye was first described in the context of laparoscopic partial cystectomy in 2012 [ 9 ]. They used endoscopic India ink inside a Deflux needle to tattoo a 1 cm outer margin around the bladder tumor. Then, they performed 10 cases of robotic partial cystectomy, and found no cases of positive surgical margins. FSA of the biopsy or resection specimens often provides critical information for decision making for adequate surgical management. FSA of the surgical margin during urological surgeries, including partial nephrectomy, radical prostatectomy, and partial or total penectomy, is useful in at least selected patients [ 14 ]. Several other studies have also suggested that FSA of the ureteral margins during radical cystectomy/cystoprostatectomy contributes to reducing the rate of final positive surgical margins [ 14 ]. However, FSA alone does not provide real-time information about the exact tumor location. Sood et al. [ 11 ] described feasibility of FSA for partial cystectomy using a concurrent cystoscope with or without a robotic ultrasound probe. Nonetheless, only a few studies in the literature have described the experience of FSA at the time of partial cystectomy [ 12 14 ]. FSA is a good candidate for use in combination with other methods. ICG is a water-soluble fluorescent dye with a molecular weight of 776 Da [ 15 ]. When ICG is stimulated by NIR of about 740–800 nm, it emits fluorescent light at a longer near-infrared wavelength (800–860 nm) [ 16 ]. This property is used to visualize various anatomical structures such as organ vascularization, lymph nodes, and identify tumor resection margins [ 17 18 19 20 ]. With respect to partial cystectomy, only a few studies in the literature have described the experience of ICG injection. Intra-tumor injection of ICG has been reported to be utilized to localize the bladder lesions to facilitate partial bladder resection [ 21 22 ]. However, tumor cell dissemination during the injection procedure, which could be concerned if the tumor is cystic or encapsulated. Therefore, the utility of ICG injection during partial cystectomy remains to be established. ICG contains sodium iodide and is not suitable in patients with a history of allergy to iodine contrast [ 23 ]. Near-infrared spectroscopy is capable of near-infrared wavelength are mounted on the da Vinci Xi surgical system (Intuitive Surgical), the 1688 AIM 4K camera system (Stryker), VISERA ELITE II system (Olympus), PDE (Hamamatsu Photonics), and Hyper Eye Medical System (Mizuho Medical) [ 17 ]. Firefly ® mode has been available since 2011 as an option to the da Vinci surgical system. The detection filter and charge-coupled device (CCD) camera of the Firefly ® mode can pick up 830 nm wavelength NIR as green colored images. The endoscopic transillumination of the luminal organs and the simultaneous activation of near-infrared spectroscopy have allowed surgeons to precisely identify the intraluminal lesions. Halogen, xenon, and LED (light emitting diode) have all recently been used as light sources, and the endoscopic white light derived from these light sources contains NIR as well as visible light. While visible light is reflected and cannot pass through the thick tissue, NIR can penetrate deeper into tissue ( Fig. 4 ). The detection filter and CCD camera of the near-infrared spectroscopy can pick up NIR. This technique of using near-infrared fluorescence without contrast agents was first reported in a case series of partial ureterectomy and partial cystectomy [ 24 ], and subsequently applied to bladder neck contracture [ 25 26 27 ], colectomy [ 3 ], hysterectomy [ 28 ], and upper gastric surgery [ 29 ] ( Table 2 ). All of these reports were successful to detect target lesion with various endoscope, and surgical margins were negative. Takahashi et al. [ 3 ] described this technique as NIRGS. In addition to the above, Watanabe et al. [ 17 ] reported a case report using the same technique for a cecal tumor. In this report, the authors preoperatively verified NIRGS technique with a silicone model using da Vinci Firefly ® mode. Then they applied laparoscopic NIRGS for cecal tumor with Stryker camera system. We found that using a cystoscope concurrently with robotic dissection of the bladder provided a real-time information about tumor location. NIRGS can be easily performed at the touch of a button on the surgeon’s console during surgery. The Tile Pro ® software of the da Vinci Xi system allows both the cystoscopist and the surgeon to visualize the cystoscopic light while viewing the console, enabling double-checking. Contrary to ICG, NIRGS does not require dye injection. That is a clear advantage of NIRGS for patients with a history of allergy to iodine contrast. There were some potential obstacles to using this NIRGS technique using cystoscopy. First, a thickened bladder wall due to abnormalities such as bladder outlet obstruction, neurogenic bladder, or chronic cystitis. In that situation, we have to fill more saline to thinning the bladder, or move the cystoscope closer to the bladder wall, or increase the exposure level of the Firefly ® mode. If these adjustments do not work, we have to try other methods such as ultrasound guidance, ICG instillation, cystoscopic tattooing, or frozen section guidance. Second, when the lesion lies outside the optical path. Urachal anomalies and urachal cancers are usually located on bladder dome. But ectopic cases or other bladder tumors could lie outside the optical path such as in the bladder trigone or posterior wall. In that case, any optical observation from outside of the bladder are not suitable, so we should try ultrasound guidance or frozen section guidance. We have not used other near-infrared devices or endoscopes, and must find out if other devices can be used. And last, the risk of positive surgical margin has not been evaluated. More cases are required to confirm the efficacy of robot-assisted laparoscopic partial cystectomy with NIRGS.

We have reported a case of urachal cyst, suspected of urachal tumor treated with robot-assisted laparoscopic partial cystectomy using NIRGS. Although this technique should be carefully considered for use in selected cases, in the future, it may be applicable to a variety of combined laparoscopic and endoscopic surgeries.

The patient is a 76-year-old woman. She was diagnosed with locally advanced rectal cancer, and was undergoing neoadjuvant chemoradiation therapy. She was scheduled to undergo robot-assisted laparoscopic proctosigmoidectomy (Hartmann’s operation). Preoperative computed tomography and magnetic resonance imaging ( Fig. 1A, B ) showed a tumor at the dome of the bladder, and she was referred to the Department of Urology at International University of Health and Welfare Hospital. Cystoscopy revealed a round submucosal mass about 10 mm in diameter at the dome of the bladder ( Fig. 1C ). Although urine cytology was negative, we could not exclude the possibility of a malignant urachal tumor. Since she was already planned to undergo robot-assisted surgery, we performed simultaneous robot-assisted laparoscopic partial cystectomy with en-bloc resection of the urachus. We obtained written informed consent for both the combined colorectal–urologic procedure. Informed consent for image publication was also obtained from the patient. This study was approved by the Institutional Review Board of International University of Health and Welfare Hospital (approval number: 24-TC-012). The period of the study from January 2022 to December 2025. The patient was placed in low-lithotomy position with a 30° Trendelenburg tilt. The 12 mm camera port was placed 2 cm above the umbilicus using the open Hasson technique. Prior to partial cystectomy by our urology team, the rectum was cut by a general surgeon with robot-assistance (da Vinci Xi; Intuitive Surgical). A skin incision was then made half around the umbilicus to the lower abdomen, and the rectum was removed by this extended incision. The median umbilical ligament was transected at the level of the umbilicus, and carried out inferiorly toward the bladder. A lap disc was attached to the extended incision, and the camera port was placed there. Then we performed robot-assisted partial cystectomy utilizing the port already placed by general surgery team, which was almost same as a usual robot-assisted radical cystectomy. Both medial umbilical ligaments were dissected from the anterior abdominal wall. The median umbilical ligament was carried out inferiorly toward the bladder. The bladder was released from the surrounding structure to permit identification of the bladder margins. A rigid cystoscope was placed into the bladder to illuminate the bladder dome, and a round submucosal mass at the dome of the bladder was clearly seen by cystoscope. We used 30° cystoscope (A22002A; Olympus), 300 W xenon short arc lamp (CLV-S40Pro; Olympus) and video processor (OTV-S7Pro; Olympus), same as usual transurethral resection of bladder tumor operation. The bladder filled with 200 mL of normal saline. Light intensity and camera exposure was automatically adjusted. This cystoscopic view was transmitted into the Tile Pro ® software of the robot to allow simultaneous visualization of bladder dome through the robotic console. In this case, we could visualize the tumor boundary without any specific adjustment. In the normal visible light mode, we could not recognize the cystoscopic light from outside the bladder ( Fig. 2A ); however, once the laparoscopic mode was changed to NIR (Firefly ® ) mode, the near infrared component of the cystoscopic light could be seen clearly as green through the bladder wall ( Fig. 2B ). The margin of the mass was circumferentially marked ( Fig. 2C ). The dome of the bladder was circumferentially excised at a distance of 1 cm from the margin of the mass along with the median umbilical ligaments ( Fig. 2D ). The bladder mucosa was repaired with a 3-0 V-Loc ® followed by a second 2-0 V-Loc ® on the muscle and peritoneum. The bladder was filled with saline and the repair was noted to be watertight. The Foley catheter was placed for drainage. The specimen was removed by extending the incision of the camera port site. Then the general surgery team made a colostomy.