The single-incision laparoscopic surgery technique has questionable advantages in colorectal surgery.

BACKGROUND: Laparoscopic procedures have increasingly been accepted as standard in surgical treatment of benign and malignant entities, resulting in a continuous evolution of operative techniques. Since one of the aims in laparoscopic colorectal surgery is to reduce access trauma, one possible way is to further reduce the surgical site by the single-incision laparoscopic surgery technique (SLS). One of the main criticisms concerning the use of SLS is its questionable benefit combined with its technical demands for the surgeon. These questions were addressed by comparing SLS versus conventional laparoscopic multitrocar surgery (LMS) in benign and malignant conditions with respect to technical operative parameters and early postoperative outcome of the patients.
METHODS: Between 2010 and 2013, we performed SLS for colorectal disease. Of the 111 patients who underwent colorectal resection, 47 patients were operated by SLS and 31 using the LMS technique. The collected data for our patients were compared according to operating time, postoperative morbidity and mortality, pain score numeric rating scale on day 1 and day 5 postoperatively and postoperative hospital stay. To complement the pain scores, the required pain medication for adequate pain relief on these days was given.
RESULTS: There was no significant difference in age, BMI or sex ratio between the two groups. The intraoperative and early postoperative course was comparable as well. Postoperative hospital stay was the only parameter with a significant difference, showing an advantage for SLS.
CONCLUSION: SLS is a feasible surgical method and a technical option in laparoscopic colorectal surgery. However, we were not able to identify substantial advantages of SLS that would favor this technique. ©2018 Schneider B. et al., published by De Gruyter, Berlin/Boston.

Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; LMS, laparoscopic multitrocar surgery; NOTES, natural orifice surgical approach; NRS, numeric rating scale for pain evaluation; NSAR, non-steroidal anti-rheumatic drug; PDC, peridural catheter; SLS, single-incision laparoscopic surgery.

Introduction

Laparoscopic procedures have increasingly been accepted as standard surgical treatment of benign and malignant entities [1], [2], leading to a continuous evolution of operative techniques. Laparoscopic surgery generally is accepted as an alternative to open colorectal surgery [3]. One of the aims in laparoscopic colorectal surgery is to reduce the access trauma to diminish postoperative pain, wound infection risks, and hernia formation in the abdominal wall. One way to achieve these goals is to further reduce the surgical site by the single-incision laparoscopic surgery technique (SLS). SLS uses only one port site. It was first described for cholecystectomy [4] and was successfully established for colorectal surgery in 2008 [5], [6]. It is a feasible technique for colorectal resection in both benign and malignant conditions [7], [8], [9], [10], [11], [12], [13]. Although SLS was shown to be suitable, relevant differences in terms of local complications and cosmetic results between SLS and laparoscopic multitrocar surgery (LMS) have not been published [14]. One of the main shortcomings of SLS is that it is questionable whether it affords a real advantage for the patient [14]. Furthermore, the technical demands for the surgeon are considered high [15]. To investigate these issues, we compared SLS versus LMS in benign and malignant conditions concerning technical operative parameters and early postoperative outcomes of the patients. We performed SLS with standard straight laparoscopic instruments. Therefore, it was our particular interest to address the learning curve for laparoscopically experienced colorectal surgeons.

Materials and methods

In November 2010, the SLS was introduced for colorectal operations in our hospital. Without restrictions, all adult patients who were scheduled for colorectal resection and had provided their written consent were included in this study. Between November 2010 and March 2013, 111 patients underwent colorectal resection. Forty-seven patients were operated by SLS. Traditional LMS was performed in 31 patients. The open technique was applied in 33 patients, most of them emergency cases without comparable patient characteristics. These cases were, therefore, not considered in this study.

The present study compares the outcome of patients who were scheduled for laparoscopic colorectal surgery using two different procedures, namely SLS and LMS. The SLS technique was applied in left-sided resections only. For right-sided colon resections, we routinely recovered the specimen through an incision in the right upper quadrant. The types of resection are shown in Table 1.

Table 1:

Surgical approach within the two groups of laparoscopic colorectal resections.

Type of resection	SLS	LMS
Sigma resection	38	21
Resection rectopexy (sigmoid resection+suture rectopexy)	6	0
Left colon, oncologic	3	3
Right colon, oncologic	0	3
Right colon, benign	0	4
Total	47	31

Data were obtained from the patients’ charts, which were prospectively documented. Details on patient characteristics [age, body mass index (BMI), sex, American Society of Anesthesiologists (ASA) category] were collected. The intraoperative and postoperative outcomes included operating time, the incidence and severity of postoperative morbidity and mortality according to the Clavien-Dindo classification [16], the pain score according to the numeric rating scale (NRS) [17] on day 1 and day 5 postoperatively, and the postoperative hospital stay.

Postoperative pain was measured on a daily basis and analyzed on days 1 and 5 after surgery. On these days, we additionally considered the required pain medication for adequate pain relief, since this has an influence on the perceived pain by the patient. The applied pain medication was subdivided into the number of patients with a peridural catheter (PDC), non-steroidal anti-rheumatic drugs (NSARs) and opioid-based medications, and we calculated the precise amount of corresponding pain medication for NSAR and opioid use. Since this outcome is divided into several facets (i.e. different medications and dosages), we refrained from performing any statistical analysis for this outcome but rather presented the data descriptively.

The data were documented in a prospective manner and reviewed as well as analyzed retrospectively.

Statistical analysis

Categorical variables are presented as percentages and were assessed by χ2 test or Fisher’s exact test. Continuous variables are presented as median and range and were compared by the nonparametric Wilcoxon two-sample test. Due to the high number of outcomes considered, we performed the Bonferroni-Holm method [18] to adjust the overall significance level of 0.05. All evaluations were performed with SAS statistical software for Windows, version 9.4 (SAS, Cary, NC, USA).

Surgical technique for SLS

If applicable, patients received a PDC system for postoperative pain management. This was the case for 16 (34%) of 47 patients. We accessed the abdomen by a 3.5-cm-long skin incision at the umbilicus. After detaching the umbilical stump, the fascia was opened to a length of 4 cm. The Gel Point® system (Applied Medical, Rancho Santa Margarita, CA, USA) was applied as the access platform. The system consisted of a transparent ring foil with a flexible internal ring and a stiff outer ring and the actual access platform. The ring foil was applied first, and the platform was clipped on top of the outer ring of the foil. A pneumoperitoneum was created (14 mmHg). The sleeve of the access device was placed in the abdominal cavity. Regular 10-mm optical systems were used along with the regular straight laparoscopic equipment in 5- and 10-mm sizes. Angled or curved laparoscopic instruments were not required with the particular access platform used. An additional 12-mm trocar was placed in the left lower quadrant for the stapling device (Endopath® ETS articulating linear cutter; Ethicon Endo-Surgery, Cincinnati, OH, USA) and was used for later drainage, which was applied routinely. Since 2013, a modified Gel Point access platform with a 12-mm trocar site has been available and has made the additional trocar site unnecessary. A silicone drainage (Robinson Charrière 18; Mediland, Rudersberg, Germany) was routinely applied for SLS and LMS. For vessel sealing, the Harmonic Ace® curved shear (Ethicon Endo-Surgery) was used. The larger vessels were additionally ligated by resorbable clips (Lapro-Clip™, Covidien, Mansfield, MA, USA).

The left colonic flexure was mobilized in all cases. The colon was prepared by a lateral-to-medial approach. After mobilization of the colon and identification of the left ureter, the mesocolon was divided close to the colon in benign diseases in a tubular-resection manner. In cases of carcinoma, the inferior mesenteric artery and the corresponding vein were primarily isolated and divided (high tie), and the mesocolon was dissected distant to the colon to ensure sufficient lymph node harvest. The specimen was divided with a cutter device (Endopath ETS articulating linear cutter) at the middle third of the rectum to ensure sufficient blood supply for the anastomosis. The specimen was extracted through the umbilical port, which was protected by the transparent ring foil supplied in the gel point set. Anastomosis was performed transanally with a circular stapler (Proximate® ILS curved intraluminal stapler; Ethicon Endo-Surgery). The anastomosis was routinely checked intraoperatively by rectoscopy and air insufflation for sufficiency and hemostasis. The fascia at the umbilicus was closed with 1 Vicryl resorbable sutures (Ethicon, Johnson & Johnson Medical, Norderstedt, Germany). The skin was closed with clips.

Results

Study population and clinical characteristics

In the study sample of 78 consecutively included subjects who underwent laparoscopic colorectal surgery, 31 patients were scheduled for LMS and 47 SLS. An overview of the study population and clinical characteristics, stratified for the two treatment groups, is given in Table 2. There was no significant difference in age, BMI or sex ratio between the two groups. The number of patients with ASA category 2 was slightly higher in the SLS group than in the LMS group, whereas the numbers of patients in ASA categories 1 and 3 were slightly higher in the LMS group.

Table 2:

Distribution of characteristics of the study population (n=78).

	SLS (n=47)	LMS (n=31)	p-Value
Age (years)	60 (37–83)	59 (28–84)	0.744
BMI (kg/m2)	25.0 (20.0–48.0)	26 (19–37)	0.782
Male sex (%)	40.4	48.4	0.488
ASA (%)			0.029
1	10.6	25.8
2	85.1	58.1
3	4.3	16.1
4	0	0

Distributions are presented as median (range) for continuous data and percentages (%) for binary data, p-values from χ2 test or Fishers’ exact test, as appropriate, for binary data and from Wilcoxon two-sample test for continuous data.

Histological findings

Histological findings and clinical classification according to Hinchey in cases of acute diverticular disease [19] stratified for the two techniques are shown in Table 3. Indication for surgery and the surgical access method were chosen as deemed suitable for the individual patient.

Table 3:

Histological characteristics of the two different laparoscopic access groups.

	SLS (n=47)	LMS (n=31)
Carcinoma	3 (6%)	3 (10%)
Adenoma	0	3 (10%)
Recurrent diverticular disease	27 (58%)	10 (32%)
Complicated diverticular disease	11 (23%)	13 (42%)
Hinchey I/II	7 (15%)	8 (26%)
Hinchey III	4 (8%)	5 (16%)
Hinchey IV	0	0
Obstructive bowel disease including cul-du-sac	6 (13%)	0
Ischemia	0	1 (3%)
Crohn’s disease	0	1 (3%)

SLS was performed mainly in elective cases of recurrent diverticular disease and for obstructive bowel syndrome. With growing experience, selected cases with an acute diverticular disease (Hinchey II and III) were also deemed suitable for the single-incision access technique. LMS was performed in elective as well as in emergency cases if patients were deemed suitable for laparoscopic access. Patients with free perforated diverticular disease and fecal peritonitis were treated by conventional open surgery. Patients with oncologic diseases were scheduled for any of the three available techniques, depending on the clinical judgment.

Comparison of the intraoperative outcomes

Five cases (9.6%) had to be converted to open surgery due to intestinal adhesions after previous abdominal surgery in the SLS group. No relevant blood loss occurred in this group, and no blood transfusion was required, either intraoperatively or postoperatively. In one case, a protective loop ileostomy was applied. The operating time for the SLS ranged from 65 to 280 min (median, 125 min).

In 9 cases in the LMS group (22.5%), conversion to open surgery was necessary due to intestinal adhesions after previous abdominal surgery in the majority of the cases and severe inflammatory adhesion in one case of emergency surgery. No blood transfusion was administered intraoperatively. The LMS operating time ranged from 55 to 210 min (median, 135 min).

To ensure an intention-to-treat analysis, the patients who underwent conversion to open surgery were not excluded from their originally assigned treatment group in any of our analyses.

The details on operation time are listed in Table 4 and Figure 1.

Table 4:

Comparison of operative outcomes.

	SLS (n=47)	LMS (n=31)	p-Value
Operation time (min)	124 (65–280)	135 (55–210)	0.440
Postoperative hospital stay (days)	7 (4–30)	9 (6–39)	0.005a
NRS, day 1	2 (0–7)	3 (1–10)	0.032a
NRS, day 5	0 (0–4)	1 (0–8)	0.042
Pain medication
Day 1
PDC (%)	16 (34%)	7 (23%)
NSAR (%)	94	97
NSAR dosage (g/day)	5 (0–8)	5 (0–5)
Opium use (%)	53	68
Opium dosage (mg/day)	7.5 (0–60)	15 (0–45)
Day 5
NSAR (%)	58	77
NSAR dosage (g/day)	4.5 (0–5)	4.5 (0–6.2)
Opium use (%)	6.4	19.4
Opium dosage (mg/day)	0 (0–22.5)	0 (0–15)

Distributions are presented as median (range) for continuous data and percentages (%) for binary data; p-values from Wilcoxon two-sample test for continuous data. aSignificant after adjustment of the global significance level, p=0.05, by Bonferroni-Holm method.

Figure 1:

Box plots of the operating time for the two laparoscopic techniques: single-incision laparoscopic surgery (SLS) and laparoscopic multitrocar surgery (LMS).

The box depicts the quartiles (bottom and top) and the median of the operative time in each group, thus containing 50% of the data. Extreme values are highlighted by extra dots above or below the whiskers.

Postoperative course

Three patients in the LMS group received blood transfusion during their hospital stay. Two patients required 5 and 2 blood transfusion units, respectively, 1 and 2 days after surgery. In both cases, a laparoscopic revision due to bleeding was indicated, as stated in the morbidity results. One patient required 1 blood unit within 5 days of surgery. In this case, no operative intervention was necessary.

Postoperative pain scale and pain medication

In the SLS group, the NRS results on day 1 ranged from 0 to 7 (median, 2). In 16 cases (34%), a PDC was applied. Twenty-five patients required morphine-based medication (53%) within the first day after operation. Of these 25 patients, 7 had received simultaneous PDC (28%). On day 5, the pain score ranged from 0 to 4 (median, 0). Three patients still required morphine-based medication (6%). Nineteen patients (40%) required no medication for pain relief.

In the LMS group, the NRS results on day 1 ranged from 1 to 10 (median, 3). A PDC was applied in 7 cases (23%). Within the first 24 h, 21 patients (68%) required morphine-based medication. Five patients (71%) with a PDC required simultaneous morphine application as well. On day 5 after surgery, the median NRS pain score was 1 (range, 0–8). Six patients (19%) required no pain medication, whereas 6 patients (19%) still required morphine-based pain medication.

The postoperative pain score on day 1 was significantly lower in the SLS group compared to the LMS group (p=0.032), and the same was true on day 5. The latter difference was not statistically significant after adjustment with the Bonferroni-Holm method (Figure 2).

Figure 2:

Box plot of the average numeric pain scale between the two surgical techniques.

The requirement for pain-relieving medication within the first 24 h after operation in terms of the need for and dosage of morphine-based medication was slightly lower in the SLS group. On day 5 after surgery, the need for opioid-based drugs was slightly lower in the SLS group than in the LMS group.

Details on the results from the NRS as well as the need for pain-relieving medication are given in Table 4 and Figure 3.

Figure 3:

Diagram showing the opioid-based pain-relieving drug requirement on day 5 for the two different surgical techniques.

Postoperative morbidity and mortality

In the SLS group, postoperative complications were observed in 13 cases (27%). They ranged from grade 1 to grade 4 according to the Clavien-Dindo classification [16]. The majority of cases (9/13; 19%) were minor complications. In 6 cases (13%), a grade 1 complication was observed: 5 cases of superficial wound infection and 1 case of prolonged bowel atonia. In 3 cases (9%), a grade 2 complication was treated with oral antibiotics: two urine infections and one pneumonia. One wound infection required vacuum dressing (grade 3a complication) and in one case, a bleeding complication required re-laparoscopy (grade 3b complication, 4%). In 2 cases, an anastomotic leakage was discovered and required re-laparoscopy as well as intensive care treatment (grade 4a complication, 4%). No grade 4b complication and no mortality were observed.

In the LMS group, a complication was observed in 9 cases (29%). Two cases of a superficial wound infection (grade 1, 6%) and three cases of grade 2 complications (one urine infection, one ileus requiring electrolyte substitution and one pneumonia requiring oral antibiotics, 9%) were observed. In three patients, a reoperation under general anesthesia was required – two cases of postoperative bleeding and one ascites of unknown origin (grade 3b, 9%). One anastomotic leakage was observed and required re-laparoscopy as well as intensive care treatment (grade 4a) (3%). No grade 4b° complication or mortality was observed in this subgroup.

No difference was observed between the two laparoscopic groups concerning postoperative morbidity and mortality (p=0.785). The complications and their distributions are detailed in Table 5 and Figure 4.

Table 5:

Postoperative morbidity and mortality according to the Clavien-Dindo classification.

Clavien Dindo classification grades	SLS (n=47)	LMS (n=31)
None	34 (72%)	22 (71%)
I°	6 (13%)	2 (6)
II° (medication required as antibiotics)	3 (6%)	3 (10%)
IIIa° (intervention)	1 (2%)	0
IIIb° (intervention requiring anesthesia)	1 (2%)	3 (9%)
IVa° (sepsis)	2 (4%)	1 (3%)
IVb° (multiorgan failure)	None	None
V° (death)	None	None
Summary of complications	13 (27%)	9 (29%)

Figure 4:

Distribution of postoperative morbidity for the two different laparoscopic approaches according to the Clavien-Dindo classification.

Postoperative hospital stay

Postoperative hospital stay in the SLS group ranged from 4 to 30 days (median, 7 days). In the LMS group, it ranged from 6 to 39 days (median, 9 days). This difference was statistically significant (p=0.005). The difference in the postoperative hospital stay is easily visible in Figure 5.

Figure 5:

Box plot of the postoperative hospital stay for the two different surgical techniques.

Discussion

Laparoscopic techniques and minimization of incisional trauma in colorectal surgery have developed rapidly within the last years. Single-incision laparoscopic surgery has been established as a minimally invasive platform, which developed from the natural orifice surgical approach. As an advantage, the SLS is performed with standard straight laparoscopic instruments if the newly developed access platforms are used. In 2008, the technique was first applied for colorectal surgery, and since then, various studies have addressed the feasibility and safety of the technique [13], [14], [15]. SLS also has been shown to be oncologically technically feasible and comparable to LMS [20], [21], [22].

In the present work, we describe the establishment and short-term outcome of a consecutive series of single-incision laparoscopic colorectal resections. Operation time did not differ between the groups in our study, which agrees with previously published data [23], [24]. Surprisingly, in the SLS group, a tendency toward a shorter operating time compared with the LMS group was observed. This fact is remarkable since the presented data were generated during the time period when the method was being established. We were expecting a learning curve with resulting prolonged operating time. The short operating time may have been due to the fact that all operations in both groups were performed by surgeons trained in colorectal laparoscopic surgery. Obviously, no time-consuming learning curve for performing SLS is necessary, which corresponds to previously reported data [25]. It seems that SLS can be easily established as an operation technique if training on laparoscopic skills is provided.

The conversion rate was also lower for the SLS group – five cases versus nine cases in the LMS group. Nevertheless, the number of conversions to open surgery is slightly higher compared to the published literature [26]. This was due to the fact that previous abdominal surgery was not considered a general contraindication for laparoscopic access [27], [28]. Furthermore, the series included elective cases as well as emergency cases. In these patients, a rather circumspect and conservative approach was defined. This means that conversion was accepted if the surgeon felt the slightest aspect of impaired patient safety. No bleeding complication occurred during the operative procedure, which highlights our careful approach.

The distribution of patient characteristics was comparable between the two groups. The histological findings differed due to the different diagnoses of the patients. Only left-sided colorectal resections were included in the SLS group because the technical aspect of the trocar placement was deemed unsuitable for right-sided colon resection. The LMS technique was suitable for both left- and right-sided colon resections.

In the postoperative course, we found no significant differences with respect to morbidity or mortality between the groups. The major complications consisted of two grade 3 and two grade 4 cases in the SLS group and three grade 3 and one grade 4 case in the LMS group. Only two cases of anastomotic leakage were observed in the whole study, both in the SLS group. These results are within the range of published literature, with a very low rate of anastomotic leakage. The number of minor complications, which had no further impact on the patient outcome or clinical results, appears rather high. This is due to the fact that even a superficial wound infection and prolonged bowel atonia were consequently documented, as intended by the Clavien-Dindo classification. These complications had no impact on the postoperative course and did not prolong the discharge of the patients.

The postoperative hospital stay was significantly shorter in the SLS group. Postoperative pain on days 1 and 5 after surgery was higher in the LMS group. On day 1, it was even statistically significant after adjustment with the Bonferroni-Holm method, which agrees with the data published in a recent meta-analysis [14].

One criticism of SLS is the potential generation of higher costs due to the use of the SLS port and longer operation time. The price of the SLS gel port is approximately €350, much higher than the price of single- or multi-use trocars. We find the expensive costs of the SLS technique to be an important aspect in the evaluation of this method.

We did not find any significant differences between SLS and LMS for most of our investigated outcomes. We also found SLS to be technically feasible without a time-consuming learning curve for an experienced laparoscopic colorectal surgeon. With regard to short-time postoperative course, SLS may be even slightly advantageous because it yielded less pain and a slightly shorter postoperative hospital stay. The intraoperative costs, however, were remarkably higher in SLS than LMS.

One limitation of our study was that the comparison was applied retrospectively. The patient inclusion in this study occurred consecutively in both groups, but the decision on the performed surgical operation method was not randomly assigned. Rather, it was chosen as deemed suitable for the individual patient. These drawbacks cannot be eliminated and might bias the presented results. This study presents the results of our first experience with SLS and should not be interpreted as confirmatory results.

In conclusion, we find no clear clinical advantages of SLS versus LMS. The detected differences for lesser pain on day 1 and a shorter hospital stay did not affect long-term clinical outcome. Hence, they do not have enough weigh to favor the new technique. Advantages in terms of fewer incisional hernias and significant advantages in the postoperative course have not been determined so far and are rather unlikely to add further evidence in favor of one technique [14]. SLS is a feasible method without significantly more adverse events during surgery within our study population. This new surgical approach adds a new technical option in laparoscopic colorectal surgery, which can be applied by an experienced laparoscopic colorectal surgeon without a time-consuming learning curve. However, we were not able to identify substantial advantages of SLS.

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