Correspondence *Department of Urology, East Surrey Hospital, Canada Avenue, Redhill RH1 5RH, UK

Email a.rane@btinternet.com

Introduction

Laparoscopy has several advantages over traditional open surgery (including decreased postoperative pain, improved cosmesis and reduced hospital stay), and its use in urologic surgery has increased exponentially over the past decade.^{1, 2, 3, 4, 5} Improvements in technology and refinement of technique have allowed urologists to perform a wide variety of complex procedures with laparoscopy, ranging from treatment of malignancy to reconstructive surgery.^{6, 7, 8} With the advent of urologic laparoscopy in the 1990s, urologists have effectively changed procedures that once used one large incision (Figure 1A) to procedures that now use several small incisions (Figure 1B). Laparoscopic surgery typically uses anywhere from three to six ports for a given procedure, with each port increasing the potential morbidity from bleeding, port-site hernia, and internal organ damage, and decreasing the cosmetic outcome.^{9, 10} As a result of the risks associated with additional ports, a surge of interest has arisen in less-invasive alternatives.

Figure 1 Illustration of open surgery versus standard laparoscopic surgery for nephrectomy.

(A) Open surgery for radical nephrectomy requires a large incision. (B) Standard laparoscopic surgery utilizes three to six ports, through which a laparoscope and surgical instruments are inserted. Triangulation between the instruments (indicated by dotted lines) allows the surgeon adequate intracorporeal working space for anatomic dissection and manipulation of tissues.

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Natural orifice transluminal endoscopic surgery (NOTES), which uses natural orifices for access to the abdominal viscera, might represent the ultimate in minimally invasive surgery by avoiding abdominal wall incisions altogether. Several authors have demonstrated the feasibility of NOTES in animal models via transvaginal, transgastric, transrectal or transvesical approaches;^{11, 12, 13, 14} however, although progress with NOTES continues to be made, several limitations hamper the broad acceptance of this new technique. In 2002, Gettman et al.¹⁵ reported the first successful experimental application of NOTES in urologic surgery when they performed six laparoscopic transvaginal nephrectomies in a porcine model. Limitations in instrumentation, such as awkward shape and lack of mobility, and a less familiar working angle and operative approach, led to a steep learning curve with resultant prolonged operative times (210–360 min). Additionally, five of the six pigs required a separate transabdominal port for completion. Other authors have also reported success with tranvaginal NOTES nephrectomy in a porcine model using both a specialized operating platform (TransPort^™ Multi-lumen Operating Platform, USGI Medical, San Clemente, CA) as well as the da Vinci^® Surgical System (Intuitive Surgical, Sunnyvale, CA).^{16, 17} In both these instances, however, a separate 12 mm transabdominal port was required for case completion. Although NOTES might be a promising surgical approach, current limitations have slowed its application to humans. The surgical difficulties encountered with NOTES, and the continued need for a transabdominal port, have led to an increasing interest in single-incision laparoscopy, where several instruments are inserted through a single abdominal or retroperitoneal incision.^{18, 19, 20}

In this Review, we will describe the terminology for this new type of single-incision surgery, the advances in instrumentation that have allowed laparoscopy to become increasingly minimally invasive, and the results of single-incision surgery for urologic procedures.

Terminology

As the role of single-incision laparoscopic surgery continues to expand, consensus on the most appropriate name for the approach has not been achieved, and several different terminologies, including single-port access (SPA) and single-access surgery, are in use (Box 1).²¹ One-port surgical procedures through the umbilicus also have various terms, including one-port umbilical surgery (OPUS), natural orifice transumbilical surgery (NOTUS),²² transumbilical endoscopic surgery (TUES),²³ transumbilical laparoscopic assisted (TULA),²⁴ and embryonic natural orifice transluminal endoscopic surgery (ENOTES).²⁵

In July of 2008, a multidisciplinary consortium of experts (the LaparoEndoscopic Single-Site Surgery Consortium for Assessment and Research [LESSCAR]) met to determine a universally acceptable name for single-incision laparoscopic surgery. The consortium determined that 'laparoendoscopic single-site surgery' (LESS) was both scientifically accurate and colloquially appropriate and, therefore, the term was ratified by the NOTES working group of the Endourological Society and will be adapted as the future standard for the reference. For transumbilical single-incision surgery, the term U-LESS will be used.

Instrumentation

The access technique for LESS or U-LESS involves using either access ports or a series of 5 mm trocars side by side in the same incision.²⁶ The TriPort^™ (Advanced Surgical Concepts, Bray, Ireland) is the best known FDA-approved access system. The size of the TriPort^™ is fully adjustable, and allows a series of instruments to be introduced into any sized abdominal incision, from a 5 mm incision up to a hand-assisted laparoscopic surgery incision. Transabdominal placement of the TriPort^™ has previously been discussed in detail.²⁷ Each device consists of a retractor component and a valve component, where the instruments are inserted (Figure 2A,B). The valve component of the TriPort^™ is made of a unique elastomeric material that allows the passage of standard laparoscopic instruments and scopes simultaneously. The TriPort^™ has three inlet valves: one inlet for a 12 mm instrument and two for 5 mm instruments. A QuadPort^™ (Advanced Surgical Concepts, Bray, Ireland) is also available, and has four ports: two inlets for 12 mm instruments and two inlets for 5 mm instruments. A separate insufflation port is provided through the valve housing in both devices. The high elasticity of the gel valve allows the removal of small specimens, whereas larger specimens are withdrawn into the distal end of the port and removed simultaneously with the device at the end of the procedure.

Figure 2 The TriPort^™.

(A) The TriPort^™ device consists of a retractor component and a valve component. The valve component is made of a unique elastomeric material that allows passage of standard laparoscopic instruments and scopes simultaneously. The TriPort^™ has one inlet for a 12 mm instrument and two for 5 mm instruments. A separate insufflation port is provided through the valve housing. The high elasticity of the gel valve allows small specimens to be removed through this route, while larger specimens are withdrawn into the distal end of the port and removed simultaneously with the device at the end of the surgery. Permission obtained from Advanced Surgical Concepts Limited. (B) The extracorporeal view of the TriPort^™ with a bent modified instrument through the superior port.

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The Uni-X^™ Single Port Access Laparoscopic System (Pnavel Systems, Cleveland, OH) is a single port with three working channels, which all accommodate specialized 5 mm laparoscopic instruments (Figure 3). The device is placed through an open access technique and requires a 2 cm fascial incision. Once passed into the abdomen, the port is anchored in place using fascial sutures that are placed before attaching the device to the patient. As with the TriPort^™, the Uni-X^™ has a separate valve port for insufflation. Once the procedure is complete, the port is untied and the specimen is removed through the initial incision.

Figure 3 The extracorporeal view of the Uni-X^™.

 

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As with all laparoscopic surgery, adequate visualization of the operative field is essential during LESS. The R-Port system can accommodate a standard 12 mm laparoscope or a smaller 5 mm deflectable-tip video laparoscope (Olympus, Orangebur, NY), while the Uni-X^™ requires a flexible laparoscope of 5 mm or 10 mm. When using a standard laparoscope, an end-on light source (Karl Stortz, Tuttlingen, Germany) should be used rather than a right-angled light source, as the latter will usually collide extracorporeally with the other laparoscopic instruments.²⁸

A basic tenet of laparoscopic surgery involves triangulation of instruments so as to produce adequate intracorporeal working space for anatomic dissection and manipulation of tissues (Figure 1B). The parallel and close proximity of the right-hand and left-hand instrument shafts of standard laparoscopic instruments through a solitary port results in crowding of the laparoscope and instruments, preventing appropriate triangulation. This problem is partly offset by prototype instruments with varying bends in the shaft or the capability to articulate (Figure 2B). Bent laparoscopic instrumentation is more cost-effective than articulating equipment because bent instruments can be sterilized and reused, whereas the articulating instruments are disposable after a single use;²⁹ however, the restriction on the degrees of freedom with bent instruments might result in a steeper learning curve than with articulating instruments. Currently, articulating laparoscopic graspers (e.g. Real Hand^™, Novare Surgical Systems, Cupertino, CA, and Autonomy Laparo-angle^™, Cambridge Endo, Framingham, MA), endoshears (Cambridge Endo, Framingham, MA), and laparoscopic needle drivers (Cambridge Endo, Framingham, MA) are commercially available for clinical use. Pre-bent instruments are not commercially available as yet.

Despite advances in surgical instrumentation, dissection through a single port is more difficult than conventional multiport laparoscopy. In order to overcome this difficulty, the instrument shafts are frequently crossed at the point of entry into the valve, such that the external right-hand instrument becomes the left instrument internally, and vice versa. As such, intraoperative dissection is often performed with the nondominant hand, requiring ambidexterity on the part of the surgeon.

In the laboratory, research has focused on technologies that avoid the frequent "sword fighting" associated with instruments inserted through a single incision, and that restore instrument triangulation. Park and colleagues³⁰ have developed a "transabdominal magnetic anchoring and guidance system" (MAGS), which can be used to control an intra-abdominal laparoscope and multiple working instruments introduced through a single 1.5 cm port. Once passed into the abdomen, instruments are affixed to the abdominal wall using external magnetic anchors (Figure 4A,B). Currently, the MAGS system incorporates an internal camera system (Figure 4C), two types of passive tissue retractors (Figure 4D), and a robotic arm cauterizer.³¹ By fixing internal instruments to external magnetic anchors, this platform allows for unrestricted intra-abdominal movement of surgical instruments, creating the potential benefits of LESS while maintaining an operative perspective similar to that of standard laparoscopy. This system has the added benefit of allowing the surgeon to reposition instruments intraoperatively without additional incisions, a benefit not realized by any other LESS technology.

Figure 4 The transabdominal magnetic anchoring and guidance system (MAGS).

(A) The MAGS can be used to control an intra-abdominal laparoscope and multiple working instruments (an internal camera system, two types of passive tissue retractors, and a robotic arm cauterizer) introduced through a single 1.5 cm port. Once passed into the abdomen, the instruments are affixed to the abdominal wall using external magnetic anchors. By fixing internal instruments to external magnetic anchors, surgical instruments can move intra-abdominally without restriction. (B) Unlike standard laparoscopic surgery (left), MAGS uses just one incision (right). (C) The intracorporeal attachment of a magnetically controlled camera in a porcine model. (D) The fixed magnetic retractor reflecting the porcine liver laterally. Permission obtained from Lippincott Williams & Wilkins © Park S, Bergs RA, Eberhart R, Baker L, Fernandez R and Cadeddu JA (2007) Trocar-less instrumentation for laparoscopy: magnetic positioning of intra-abdominal camera and retractor. Ann Surg 245(3): 379–384.

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Clinical results of laparoendoscopic single-site surgery

Attempts to perform urologic surgery through a single incision began with a report by Hirano et al.²⁰ in 2005. The investigators used a specialized resectoscope tube with a 4 cm diameter and standard laparoscopic instruments to perform a retroperitoneoscopic adrenalectomy. The advances in instrumentation reported above have led to a substantial growth in the use of LESS over the past several years. Rane et al.³² reported the first urologic use of a single multifunctional port in an abstract and video presentation at the 25th World Congress of Endourology meeting in Cancun, Mexico in 2007. The authors were able to complete the first single-port nephrectomy for a small nonfunctioning kidney, as well as a transperitoneal ureterolithotomy, with a mean operative time of 90 min and no intraoperative complications. The authors have since reported their initial wider experience with the device for benign urological disease.²⁷

In early 2007, Raman et al.²⁶ reported their initial experience with keyhole nephrectomy in pigs and humans using a single incision to introduce three adjacent trocars (one 10 mm and two 5 mm) (Figure 5). Initial experience involved bilateral nonsurvival nephrectomy in four female farm pigs (eight kidneys) and, once the technique was perfected, keyhole nephrectomy was performed in three human patients. Using a combination of bent and articulating instruments, Raman and colleagues were able to complete the three human nephrectomies with a mean operative time of 133 min (range 90–160 min) through a mean incision of 3 cm (range 2–4.5 cm). In this small series, no complications were encountered and all human patients were discharged on their second postoperative day.

Figure 5 Transumbilical laparoendoscopic single-site surgery.

Three adjacent 5 mm trocars are introduced through a single umbilical incision.

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LESS has also been performed through a GelPort^® (Applied Medical, Rancho Santa Margarita, CA), which was initially designed for hand-assisted laparoscopic surgery.³³ Furthermore, Zeltser and Cadeddu³⁴ completed the first two successful nephrectomies with the MAGS technique in a porcine model as proof of concept in 2007.

Several other small clinical series from multiple academic institutions have continued to support the feasibility and safety of LESS in patients with urologic disorders (Table 1). Surgeons have now used the innovative technology to perform single-incision nephrectomy,³¹ pyeloplasty,³⁵ adrenalectomy,³⁵ uretolithotomy,³² orchiopexy,³² orchiectomy,³² renal cryotherapy,³⁶ wedge renal biopsy,³⁶ sacrocolpopexy,³⁶ partial nephrectomy,³⁷ and pediatric varicocelectomy.³⁸ In addition to these published cases, surgeons at the Cleveland Clinic have also performed ileal ureter creation, radical prostatectomy, and radical cystectomy with extended lymph node dissection (JH Kaouk, personal communication).

Table 1 Reported urologic experience with laparoendoscopic single-site surgery.

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Although early clinical experience with LESS seems promising, several issues must be overcome before it can become widely used in urology. Surgeons must master the use of novel bent and articulating instruments in close proximity to one another, in addition to learning standard laparoscopy skills. The surgeon and assistant also need to work together in close proximity, and the technique requires a skilled camera driver and constant coordination. Furthermore, continued refinements of prototype instruments are required in order to prevent instrument collision, while increasing the working area available to each laparoscopic instrument.

Several clinical questions surrounding the use of LESS also remain. What is the best way to extract large specimens? Is one technology superior to another? And, most importantly, does LESS improve clinical outcome compared with standard laparoscopy? A retrospective case–control study that compared keyhole nephrectomy with standard laparoscopic nephrectomy in 11 LESS procedures and 22 standard laparoscopy procedures demonstrated no difference in median operating room time (122 min vs 125 min), change in hemoglobin levels, analgesic use, length of hospital stay, or complication rate between the two approaches.³⁹ A limitation of this study, in addition to it being retrospective, is that patients had their nephrectomy specimens removed through an extension of the umbilical incision up to 4–6 cm, thus clouding the possible benefits of LESS, such as shorter convalescence and reduced postoperative pain, compared with standard laparoscopy. These results might not indicate any advantages of LESS over standard laparoscopy; however, future prospective trials are necessary to determine which patients, if any, might benefit from this new technology.

Conclusions

LESS in urology is in its infancy. Further refinements in instrumentation and operative techniques will be required before this method of surgical access can be widely accepted. Before use in the broader population, prospective, randomized studies are required to determine the true benefit and utility of this novel surgical approach compared with current alternatives.

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