OBJECTIVE: To compare postoperative pain after conventional laparoscopic and robotically assisted laparoscopic surgery in gynecology.
METHODS: This is a prospective nonrandomized analysis of patients undergoing conventional laparoscopy or robotically assisted laparoscopy in a university-affiliated hospital between March 2011 and March 2012. Postoperative pain was measured using the Numeric Rating Scale and the narcotic use converted to morphine sulfate equivalents. The primary outcome was the Numeric Rating Scale pain score obtained on the first postoperative day.
RESULTS: One hundred ten patients were enrolled; 91 were included in the statistical analysis. Both groups were similar with regard to race, history of abdominopelvic surgeries, psychiatric history, and substance abuse. Patients undergoing robotically assisted laparoscopy were 6 years older and had a body mass index 6 points higher. Median length of hospital stay for conventional laparoscopy and robotically assisted laparoscopy was 2 days and 3 days, respectively (P<.001); median to being off narcotics was 4 days and 4.5 days, respectively (P=.336); and median return to normal activities was 13 days and 21 days, respectively (P=.021). There were no significant differences in mean Numeric Rating Scale pain scores over time (P=.499) or mean narcotic requirements (P=.393) between groups.
CONCLUSION: Robotically assisted laparoscopy is equivalent to conventional laparoscopy in terms of subjective and objective measures of postoperative pain.
LEVEL OF EVIDENCE: II
This prospective comparison of postoperative pain between laparoscopic and robotic gynecologic surgery shows no difference in pain scores or narcotic requirements over time between these approaches.
Department of Obstetrics and Gynecology, St. Luke’s–Roosevelt Hospital Center, New York, New York.
Corresponding author: Farr R. Nezhat, MD, 425 W 59th Street, Suite 9B, New York, NY 10019; e-mail: FNezhat@chpnet.org.
Financial Disclosure The authors did not report any potential conflicts of interest.
Conventional laparoscopy has assumed an important role in gynecology and other specialties, primarily because of its minimally invasive character compared with open surgical approaches. Known advantages of laparoscopy over laparotomy include improved visualization, decreased blood loss, less postoperative pain, shorter hospital stay, faster recovery, and better cosmetic results.1–6 However, pitfalls of conventional laparoscopy include a long learning curve for the surgeon, counterintuitive hand movement, and limited instrument degrees of freedom in the abdominopelvic cavity.7
Computer-enhanced telesurgery, also called robotically assisted laparoscopy, was conceived to circumvent drawbacks of conventional laparoscopy. It emerged as a breakthrough technology and has spread in less than a decade over many surgical fields including urology, cardiothoracic surgery, pediatric surgery, otolaryngology, and general surgery. The da Vinci surgical system achieved Food and Drug Administration approval for gynecology in 2005.8 This technology offers a shorter learning curve, three-dimensional optics, and enhanced surgical dexterity through wristed instrumentation and tremor filtration. However, known areas of vulnerability of the robot include the loss of tactile feedback to the surgeon, the high costs involved, and the time spent on assembly and disassembly of the robot.7,9,10
Decreased postoperative pain has been associated with improved outcome and patient satisfaction, a reduction in opioid consumption, and subsequently fewer side effects.11 Studies suggest conflicting results regarding postoperative pain and recovery time after robotically assisted laparoscopy. There are few prospective studies comparing conventional laparoscopy with robotic-assisted laparoscopy and none has focused on postoperative pain as the primary outcome.
The objective of our study is to prospectively compare patient-reported pain, analgesic requirement, and recovery time between patients undergoing conventional laparoscopy and those undergoing robotic-assisted laparoscopy. We hypothesized that the robotic approach would cause increased postoperative pain as a result of the size and location of the incisions, instrument weight, position shifting against docked robotic trocars, and the subsequent trauma to the abdominal wall.
MATERIALS AND METHODS
Institutional review board approval was obtained from St Luke's–Roosevelt Hospital Center for this 12-month prospective study, which took place between March 2011 and March 2012. Patients were treated at St Luke’s–Roosevelt Hospital Center, an urban university-affiliated hospital. All the cases were performed by one surgeon (F.R.N.) with extensive experience in advanced laparoscopy and robotic surgery, a fellow in minimally invasive surgery, and a resident in gynecology.
Patients who are 18 years or older, able to understand and comply with the instructions of the study, and those undergoing conventional laparoscopy or robotic-assisted laparoscopy were recruited in the study. All patients meeting criteria of inclusion signed a preoperative consent form. The choice of the route of the procedure was based on surgeon–patient preferences. Exclusion criteria included any conversion to laparotomy and refusal to participate in the follow-up assessment.
Demographic and surgical data were both retrieved from patient charts. Demographic data included age, race, body mass index (BMI, calculated as weight (kg)/[height (m)]2), and possible confounders such as antecedent abdominopelvic surgeries, chronic narcotic use, psychiatric history, and toxic habits. Surgical data included a description of the procedure performed, estimated blood loss, and any intraoperative complications. Operative time was measured from the surgical incision to the closure of the skin. Conventional laparoscopy port placement consisted of a periumbilical 5- to 10-mm port, 5-mm ports in both right and left lower quadrants, and a 5- to 10-mm suprapubic port in certain cases. On the other hand, robotically assisted laparoscopy consisted of a supraumbilical 12-mm camera port, 8-mm robotic ports in the right and left side of the midabdomen, and a 5- to 12-mm ancillary port in the right or left upper quadrant. Fascia closure was performed using the laparoscopic closure device for all incisions longer than 5 mm. The skin layer was closed in a subcuticular manner or using steri-strips. Cumulative surgical incision lengths based on the number and size of trocars were noted. The procedures performed were classified according to their complexity. A procedure was considered complex if it included pelvic, paraaortic, or both lymphadenectomy, advanced endometriosis, extensive adhesions, or a hysterectomy for a uterus weighing more than 250 g. The nursing flow sheets were used to extract pain scores and narcotic use in the hospital. Postoperative analgesia was provided according to the patient's request. The postoperative course was monitored and parameters such as the hospital length of stay (LOS) and postoperative complications were collected. The LOS was measured in days and patients discharged the day of surgery were considered to have a LOS of 1 day.
Our aim was to compare subjective and objective measures of postoperative pain and recovery between both surgical approaches. Postoperative pain was evaluated subjectively by using the Numeric Rating Scale, a reliable and validated pain intensity measure. It relies on numbers ranging from 0 to 10 to measure pain intensity, 0 being the absence of pain and 10 being the worst pain imaginable. The Numeric Rating Scale was selected because it is more commonly used in clinical practice.12 On the other hand, objective assessment of pain was based on the amount and type of analgesics used. All narcotic use was converted to morphine sulfate equivalents using a validated equianalgesic dose table. The concept of equianalgesia refers to the theory that doses of different opioids can provide equivalent pain relief. Parenteral morphine at 10 mg was used in initial equianalgesia studies and is considered the gold standard for conversion.13 Therefore, patients completed a pain diary that was collected on the 2-week postoperative visit. Patients kept track of the severity of the pain through daily pain scores and recorded the name of the analgesic medication taken and the number of tablets consumed. They also recorded their return to baseline activities, described as “feeling back to normal,” specifically the time needed to resume work or daily activities (shopping, laundry washing). Patients were seen in the office 2 weeks after the surgery and they were followed until their final postoperative visit. Patients were contacted 6 weeks postoperatively—6 weeks being considered the classic recovery period—to inquire about any complications, the 6-week Numeric Rating Scale pain score, and the date of resumption of normal activities.
The primary outcome measured in this study was the Numeric Rating Scale pain score obtained on the first postoperative day. We considered a difference of 1.5 in mean pain scores to be clinically relevant given the lack of prior comparative data. We also took into account the proportion of cases performed by the primary surgeon using conventional laparoscopy (60%) and robotic-assisted laparoscopy (40%). Power analysis was performed for a two-sample t test with a .05 two-sided significance level. Assuming a common standard deviation of 2.3, we needed a sample size of 80 patients with 48 patients and 32 patients in the conventional laparoscopy and in robotically assisted laparoscopy groups, respectively, to achieve 80% power in detecting a difference of 1.5 in mean Numeric Rating Scale pain scores. Based on a 20% estimated loss to follow-up rate, we aimed at recruiting 100 patients in the study.
All statistical analyses were conducted with SAS 9.2 software. Continuous data were described as medians with ranges or means with standard deviations; categorical data were expressed as percentages. Means of continuous measures were compared between study groups using a Student's t test and medians were compared using a Wilcoxon rank-sum test. Proportions of categorical variables were compared between study groups using a Pearson's χ2 test. A mixed regression model with unstructured covariance and random intercepts was used to estimate and compare trends in pain scores over time between patient groups. Because the distribution of narcotic medication requirements was log-normal with left-censoring at zero (patients who were not taking any medication at a particular visit had a medication requirement of zero), a left-censored Tobit mixed regression model with a log-normal distribution and random intercepts was used to estimate and compare trends in narcotic medication requirements over time between patient groups.14 All hypothesis testing was conducted at the .05 level of significance.
One hundred ten patients signed a preoperative consent form for the study; however, nine patients were excluded because of an intraoperative conversion to laparotomy and 10 patients did not participate in the follow-up assessment. Therefore, 91 patients were included in the statistical analysis, 52 in the laparoscopy group and 39 in the robotic group. The 2-week follow-up was obtained in 51 and 37 patients in the conventional laparoscopy and robotically assisted laparoscopy groups, respectively, whereas the 6-week follow-up included 43 and 25 patients, respectively. Figure 1 describes the study flow chart in more detail.
The baseline characteristics of the study population are summarized in Table 1. There was a significant difference in age and BMI between groups. Patients in the robotic group were on average 6 years older and had a BMI of 6 points higher than the laparoscopy group. They were comparable with regard to race, antecedent abdominopelvic surgeries, psychiatric history, chronic narcotic use, and substance abuse. Table 2 shows the perioperative data of the two study groups. The procedures in both groups were comparable in their complexity, although the robotic group had a higher rate of hysterectomies performed. Robotic cases had a longer mean surgical time but had comparable mean blood loss and rate of intraoperative or postoperative complications. Mean cumulative incision lengths for conventional laparoscopy and robotically assisted laparoscopy were 2.40 cm and 3.96 cm, respectively (P<.001). Median LOS in the laparoscopic and robotic groups were 2 days and 3 days, respectively (P<.001) (Table 2).
With regard to pain scores over time (P=.499) or mean peak pain scores (P=.480), there was no statistically significant difference between laparoscopic and robotic procedures (Fig. 2; Table 3). In addition, there was no statistically significant difference in the narcotic medication requirements over time between both groups (P=.393) (Fig. 3). Adjusting both the mean pain scores and the narcotic requirements for age and BMI did not affect our statistical outcome. The median time to being off narcotics was 4 days for the laparoscopy group compared with 4.5 days for the robotic group (P=.336) (Table 4). The median return to normal activities in the laparoscopic and robotic groups was 13 days and 21 days, respectively (P=.021) (Table 4). On the other hand, analysis of a subgroup of patients who underwent laparoscopic hysterectomy (n=22) compared with robotic-assisted hysterectomy (n=25) showed no statistically significant difference in pain scores over time (P=.590) and no statistically significant difference in narcotic medication requirements over time (P=.091).
Postoperative pain and recovery have always been a major concern for patients and an inherent feature of preoperative counseling. Minimizing the amount of postoperative pain and subsequently the use of narcotic medications affects the overall morbidity of a surgical approach and should be considered one of the priorities of routine operative practice. There is a paucity of data regarding postoperative pain and recovery time after robotically assisted laparoscopy and the literature is lacking prospective comparisons between conventional laparoscopy and robotically assisted laparoscopy. Different studies suggest minimal pain, a short hospital stay, and fast recovery in robotically assisted laparoscopy. In a case-series of 91 patients undergoing robotic hysterectomy, Kho et al15 report an average hospital stay of 1 day. When comparing perioperative outcomes of different approaches for radical hysterectomy, Nezhat et al and Magrina et al found a similar LOS in the robotic-assisted and laparoscopic groups16,17 that was significantly reduced compared with the laparotomy group.17 In urology, a prospective study comparing retropubic radical prostatectomy with robotic-assisted laparoscopic radical prostatectomy demonstrated low postoperative pain scores in both groups with no significant difference.18 On the other hand, studies comparing robotic with abdominal sacrocolpopexy showed similar postoperative pain19 but shorter LOS in the robotic approach.20
The possibility of increased postoperative pain in robotic surgery has been raised in recent literature. Authors have questioned whether robotic surgery confers patients the same benefits as laparoscopy. In the randomized controlled trial by Paraiso et al21 comparing 40 robotic with 38 laparoscopic sacrocolpopexies, patients had higher visual analog scale pain scores at rest and with normal activities from weeks 3–5 postoperatively but similar narcotic use and return to normal activities. We had also hypothesized that the robotic approach would cause increased postoperative pain. Our assumption was based on the thought that the increased number and diameter of the ports, the anatomic distribution of the trocar sites across the abdominal wall, and the use of heavy robotic instruments would cause more traumatic injury to the abdominal wall. In this study, the cumulative length of the incision in the robotically assisted laparoscopy group was significantly greater than in the conventional laparoscopy group. However, our study shows no statistically significant difference in the subjective and objective measures of postoperative pain after laparoscopic or robotic-assisted laparoscopic gynecologic surgeries. In fact, the robotic endoscopic arms move around fixed pivot points at the level of the skin, which reduce port site trauma and this fulcrum effect might counterbalance the other factors implicated in the increased postoperative pain. Our statistical power analysis aimed at detecting a difference of 1.5 points in the Numeric Rating Scale pain score, which in our opinion would be clinically relevant. On the other hand, the robotically assisted laparoscopy group had a significantly longer median time to return to normal activities. This difference needs to be confirmed with randomized studies. The older age in this group might have contributed to the longer recovery time and our assessment of the postoperative recovery time could benefit from more objectivity. In fact, validated instruments to assess the recovery time have been described in the literature and include portable devices or accelerometers that measure motion in three dimensions to quantify physical activity in postoperative patients.19
Robotic surgery has certainly been the subject of extensive marketing campaigns and patients as well as health care providers are frequently biased toward the advantages of new technology. A study looking at the prevalence and content of robotic surgery information presented on U.S. hospital web sites found that 41% of hospital web sites described robotic surgery with 89% of them giving statements of clinical superiority, the most common being less pain and shorter recovery.22 However, to our knowledge, there is a lack of scientific evidence that robotic surgery is better than video-assisted laparoscopy in terms of postoperative pain and recovery time.21,23 Furthermore, the literature has clearly shown longer mean operating times23–26 and increased costs27 related to robotic assistance. A recent study even postulated that the more aggressive dissection of the bladder performed with robotic hysterectomies may be associated with an increase in urinary retention when compared with laparoscopic hysterectomies.28 Acknowledging these potential drawbacks of robotic surgery will allow health professionals to balance the uptake of new technology to further enhance patient care.
The main factor limiting our study is the lack of randomization. The choice of the surgical approach was the result of the preoperative discussion between the surgeon and the patient and introduces a potential selection bias in our study. The older age and higher BMI in the robotic group could reflect surgeon preference. The older population might have a higher pain tolerance compared with the younger population, but it is unclear whether this is clinically relevant.29 Adjusting the mean pain scores and narcotic requirements for age and BMI showed neither variable to be a significant confounder of the association between outcome and treatment group. On the other hand, although there was a disparity in age and BMI, both groups were comparable with regard to potential confounders affecting the perception and quantification of pain such as psychosocial status, substance dependence, and surgical history. The study included a heterogeneous set of procedures with equal complexity overall, but predominance of hysterectomies in robotically assisted laparoscopy. However, when looking at a subgroup of patients who underwent hysterectomies using both approaches, the statistical comparative results mirrored those of the primary analysis. A post hoc power analysis looking at our primary outcome measure of mean pain scores on postoperative day 1 using a two-sided α of 0.05 and assuming a common standard deviation of 2.3, shows that the hysterectomy subgroup sample size yields an 80% power to detect a difference of 2 in mean pain scores. The strengths of this study reside in its prospective nature and the use of both subjective and objective standardized measures of comparison. Postoperative pain can be perceived in multiple ways; consequently, we resorted to different evaluation tools. The Numeric Rating Scale is a validated pain measurement tool in the literature, and the assessment of narcotic use converted to morphine sulfate equivalents offers appropriate means of eliminating the confusing diversity in narcotic medications. Objective measures were particularly valuable in this setting because there is a strong bias from patients and surgeons regarding the new robotic technology.
In conclusion, the current study demonstrates that, compared with conventional laparoscopy, the robotic approach confers the same amount of postoperative pain over time and need for analgesia and sheds a doubt on the presumption that robotic surgery decreases postoperative pain when compared with laparoscopy. Robotically assisted laparoscopy had significantly longer operating time, hospital stay, and return to baseline activities compared with conventional laparoscopy. With this in mind, and in the hands of an experienced laparoscopic surgeon, robotically assisted laparoscopy does not seem to offer any advantages to conventional laparoscopy in terms of postoperative pain and recovery. Further randomized studies are needed to confirm our results.
Robotic surgery has revolutionized the minimally invasive field. However, it is still in its infancy and remains a fertile ground for innovation and progress. There are undeniable advantages to the robot, especially in procedures with increased complexity or in obese patients. The range of motion provided by endowrist instrument tips and the remarkable hand–eye–instrument coordination are noteworthy technology advancements allowing for the surgeon's hand to be scaled, filtered, and translated into precise movements. However, continued and prompt progress in surgical instrumentation is essential and will leverage the robotic field to its full potential.
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© 2013 The American College of Obstetricians and Gynecologists
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