Single-Incision Laparoscopic Surgery and the Necessity for Prospective Evidence

Introduction

Laparoscopy as a surgical modality has exploded over the last 20 years and represents one of the most significant surgical advances in modern times. We now know that laparoscopy has proven benefits with regard to postoperative pain, cosmesis, and convalescence. However, at its introduction, laparoscopy was adopted without appropriate clinical evidence to justify the approach as an alternative to open surgery. In continued efforts to increase the benefits of minimally invasive surgery (MIS) to their patients, surgeons have innovated new techniques to further decrease the impact of the operation on patients. These innovations range from decreasing the size of ports and instruments to the current group of techniques termed “scarless” surgery.

The concept of evidence-based medicine is no longer a movement of progressive physicians, but a basic guiding principle of medical training and practice. Surgeons have traditionally trailed medical disciplines in both the acquisition of high levels of evidence and the application of evidence into practice. New techniques are often initially attempted by progressive surgical innovators and then adopted by others without formal training, observation, or apprenticeship. In the current medical environment, this is becoming less acceptable, and it is the surgeon's responsibility to prove that the benefits outweigh the risk before new techniques are widely applied to patients. This article seeks to review the history of laparoscopic surgery, apply lessons learned to the evolution of single-incision laparoscopic surgery (SILS), and make a statement urging for sound, prospective evaluation. Prospective studies are necessary to qualify which outcome variables are affected by single-site approaches, and to quantify the degree of differences in those variables, so that surgeons may consult patients appropriately about the new procedures.

Transition from Open to Laparoscopy

The first laparoscopic appendectomy was performed in 1981 by German physician Kurt Semm. As with most innovations, it was met with apprehension and resistance. It was not until 1987, when Phillippe Mouret performed the first credited laparoscopic cholecystectomy, that laparoscopic surgery was widely accepted. The benefits of the laparoscopic approach became apparent, with hospital stay reduced from 5 to 1–2 days and convalescence reduced from 3–6 to 1–2 weeks. Within 2 years, there was a massive demand for this procedure, motivated mainly by market forces and patients. Laparoscopy was being advertised to the public as “surgery without knives.” The approach was also seen by hospitals as an opportunity to increase their profitability by reducing length of stay. Surgeons were pressured by these forces, and the surgical community adopted this technique without the standard stages of scientific evolution supported by evidence. The rapid, widespread application of laparoscopic cholecystectomy by surgeons not trained in the laparoscopic era resulted in a dramatic rise in the dreaded, unacceptable complication of bile duct injury. ¹ This prompted the National Institutes of Health (Bethesda, MD) to hold a consensus conference in 1992. ² The panel called their task of evaluating the available data on laparoscopic cholecystectomy as an attempt to analyze a “swiftly moving target.” They sited a wide array of limitations in the data, including retrospective nature, bias toward reporting favorable results, short follow-up times, a learning curve, and variation in surgeon techniques and skills. Despite these limitations, they concluded that laparoscopic cholecystectomy is safe and effective and offers the benefits of decreased pain and convalescence. Although the data showed that the rate of common bile duct injuries was increased, the rate was still low enough to conclude that the benefits outweigh the risks. However, the consequences of some bile duct injuries are so catastrophic, that evaluation of the results also becomes a challenging task. Since a guiding principle of evidence-based medicine, in the evaluation of comparative therapies, is assessment of risk, these injuries need to be appreciated. It is difficult to weigh the catastrophic outcomes of a few patients against the clear benefits experienced in the remaining population. This arduous evaluation will be important to consider, with the progression to single-site surgery, which has the potential to pose a similar quandary to surgeons and patients. It is important to recognize, in this process, that the potential benefits of single-site surgical approaches over laparoscopy are not nearly as large as the leap from open approaches to laparoscopy, further emphasizing the need for sound data.

The difference in the patient's experience of an operation after the introduction of laparoscopy was immense, due to the morbidity of open incisions. The laparoscopic approach to those operations, with the most morbid incisions, such as cholecystectomy, fundoplication, splenectomy, nephrectomy, adrenalectomy, and other procedures, quickly became the preferred modality without prospective, comparative data. The transition from open to laparoscopy for these operations is not a good model for the move toward single-site procedures, because the incremental improvement of single-site over conventional laparoscopy is small, if even real. We must examine situations where the open operations are associated with less morbidity, thus offering fewer benefits when performed laparoscopically. This was the case with the appendectomy, which is why widespread use of laparoscopy for appendectomy was slower to be applied. ³ Contributing factors to the delay of routine laparoscopic appendectomy included performance of appendectomy during night hours and uncertainty of creating a pneumoperitoneum with peritonitis. In this setting, the more subtle clinical improvement with laparoscopy precipitated the gathering clinical evidence before it became the approach of choice. The first patient series began to surface in the early 1990s and showed that the laparoscopic appendectomy was feasible. This sparked numerous randomized, controlled trials to compare open versus laparoscopic appendectomy.^4–6 The trials had mixed results, which sparked controversy over whether the laparoscopic appendectomy was superior to the open appendectomy. Advocates of the laparoscopic approach sited shorter length of hospitalization, less pain, less recovery time, improved visualization of the abdomen for other diagnosis, and similar complications between the two approaches. Critics of the laparoscopic approach argued that the benefits of the laparoscopic appendectomy was marginal, compared to the open appendectomy, and some studies found longer operating times and higher costs. To address these controversies, several meta-analyses and systematic reviews were performed on these trials.^7,8 They were able to show decreased pain, shorter hospital stay, and decreased wound-infection rates in patients that underwent the laparoscopic appendectomy. Other benefits of the laparoscopic appendectomy included improved cosmesis and the ability for diagnostic laparoscopy. These analyses did not find a significant cost difference between the two approaches, due to improvements in equipment and operative times. Based on these findings, the general consensus is that the laparoscopic appendectomy has advantages over the open appendectomy, and the surgical community has accepted the use of this approach. Since we are currently on the cusp of the introduction of single-site operations, we can learn from the example of the laparoscopic appendectomy to conduct highly powered trials at the outset to prevent a protracted debate in the literature, based on lower levels of evidence.

Transition Toward Single-Site Approaches

As surgeons recognized the benefits of laparoscopic surgery to their patients, minimally invasive surgery expanded and was applied to numerous procedures, with varying amounts of clinical evidence. With increased experience and improved instrumentation, surgeons began to modify laparoscopic approaches to further decrease the invasiveness. Today, this quest for even more minimally invasive surgery has led to single site operations. These techniques range from laparoscopic surgery through a single umbilical site (i.e., SILS) to natural orifice surgery performed through the vagina, urethra, mouth, or anus, called natural orifice translumenal endoscopic surgery (NOTES). The rationale for performing a procedure through a single-access site is that reducing tissue trauma will translate into reduced pain, shorter hospital stay and recovery, and improved cosmesis. Despite the potential benefits to patients, these procedures have potential risks. There are obvious safety concerns with creating an opening in a viscous for access to perform a NOTES procedure, which has sequestered its application to animal models and sparse case reports. The SILS approach also has safety concerns with increased technical difficulty. A wide spacing of instruments is fundamental to laparoscopic surgery in order to allow for tissue retraction, proper dissection along planes, less crowding of instruments, and improved depth perception when the camera is not in parallel with the instruments. When the surgeon is limited to performing laparoscopic procedures through a single incision, these advantages are lost, and the safety of the procedure may be affected. Remembering the reported increased incidence of intraoperative bile duct complications when laparoscopic cholecystectomy was first introduced, it is an undoubted concern that we may see the same phenomenon occur with the application of the SILS approach. SILS proponents argue that SILS is not an adaptation of a new surgical style, as was the case in the introduction of laparoscopy, since advanced laparoscopic surgeons usually perform these techniques. However, the techniques do violate the basic principles of safe laparoscopic surgery, as outlined above.

In addition to intraoperative concerns, the single-site approaches impose a new set of considerations, compared to standard laparoscopy. In single-incision surgery, the umbilical incision is larger than for standard laparoscopy. Thus, we appear to have evolved from a single, large incision (i.e., open surgery) to many small “poke holes” (i.e., laparoscopy) and to a single, larger incision, which is smaller than the open approach (i.e., SILS). Most cannula/instrument introduction techniques do not divide muscle, but simply dilate a thin tract. The SILS approach requires a substantial fascia-splitting incision, which may translate into more surgical infections, more pain, and an increased risk for postoperative hernias.^9,10

Regardless of the risk of complications, the relative advantages of single-site procedures are small, compared to standard laparoscopy. It would appear that the only possible advantage is cosmesis. Theoretically, the cosmetic advantage would be the greatest where incisions are made in the epigastrum and are highly visible in specific circumstances, such as swimwear or toplessness. The cosmetic advantage also depends on appropriate reconstruction of the umbilicus. We have seen patients after single-site operations whose umbilicus has looked good to the surgeon, but not exactly satisfactory to the patients, who have been dissatisfied with the umbilical appearance. The conversion of cosmesis introduces an interesting dilemma with the single-site umbilical operation. The more obese the patient, the easier it is to make an invisible incision. However, this type of patients, frankly, has less abdominal cosmetic concerns, rarely exposing the abdomen. On the other hand, the lean swimwear-sporting population, who often hold great concern over abdominal appearance, typically possess an umbilicus that makes it difficult or impossible to hide the entire scar in an invisible manner. This emphasizes the importance of gathering prospective, randomized data that would evaluate every outcome variable, including patient perception of scarring. This must be done so we can understand what the advantages and disadvantages are and, most important, how these influence the perception of the patients, not the surgeons. Retrospective series concluding an excellent cosmetic outcome, based on the surgeon's perception, are, frankly, inadequate and inappropriate without supporting data.

Future Direction Guided by Data

Despite the concerns about single-site surgery, the approach lies on the cutting edge of surgery, and its potential benefits to patients cannot be ignored. With the advanced laparoscopic skills of today's surgeons and improved instrumentation available to them, it is possible that surgery may be offered to patients through a single incision with adequate safety and improved benefits. Preliminary reports on single-site surgery focus on feasibility.^11–16 Initial experiences tend to show that the procedures have reasonable operating times and at least comparable outcomes to traditional laparoscopic approach. Regardless, at the current time, the surgical literature lacks prospective data to document any benefits afforded by single-site surgery. It would be a shame for the surgical community to repeat history and let market and patient forces push the adoption of techniques before clinical evidence dictates that benefits outweighs the risk. Therefore, we are currently accruing patients in three separate prospective, randomized trials.

The three trials currently enrolling subjects include patients requiring an appendectomy for nonperforated appendicitis, cholecystectomy, and splenectomy. In these studies, subjects are randomized to either a single-incision umbilical approach or a standard laparoscopic operation. All have been developed with definitive design. Operative time, complications, doses of postoperative analgesics, time of convalescence, and other variables are being compared. Since it appears that the major potential benefit offered by the single-site approach is cosmesis, all patients are completing an extensive, validated scar-appreciation questionnaire. ¹⁷ This questionnaire is done at 6 weeks and 6 months after the operation.

Conclusions

We encourage other surgical centers to embark on such studies and welcome joint enrollment for willing investigators. These studies will provide definitive information that will allow surgeons and patients to understand the precise implications of single-site procedures.