Does Single-Port Laparoscopic Surgery Reduce Postoperative Pain in Women with Benign Gynecologic Disease?

Abstract

Background:

Reduced postoperative pain, one of the potential benefits of single-port laparoscopic surgery (SP-LS), has clinically significant importance. The objectives of this study are to compare postoperative pain between SP-LS and conventional laparoscopic surgery (conventional-LS) and to evaluate the difference in postoperative pain between the SP-LS group and the conventional-LS group based on whether a hysterectomy was performed.

Subjects and Methods:

We performed a prospective case-control study among women who underwent SP-LS (n=116) and conventional-LS (n=283) for benign gynecologic disease. We evaluated postoperative pain with a visual analog scale for pain score and the requirement for additional analgesics at 2, 4, 6, 12, 24, 48, and 72 hours after surgery.

Results:

The pain score was significantly lower in the SP-LS group compared with the conventional-LS group only at 2 hours after surgery (5.70±2.33 compared with 6.38±2.13, P=.005). However, at all assessment times (2, 4, 6, 12, 24, 48, and 72 hours) after surgery including a hysterectomy (n=188) and all assessment times except 2 hours after surgery that did not include a hysterectomy (n=211), there were no differences in pain score when comparing the SP-LS or conventional-LS groups.

Conclusions:

Single-port laparoscopy had no effect on postoperative pain except in the immediate postoperative state (2 hours following surgery) in women who underwent surgery that did not include a hysterectomy.

Introduction

Single-port laparoscopic surgery (SP-LS) has been recently attempted in various surgical fields, and several initial studies using SP-LS have been reported.^1–8 SP-LS is expected to have multiple advantages, including shorter hospital stays, faster recovery times, better cosmetic outcomes, and reduced postoperative pain.^9,10 There have been considerable numbers of studies evaluating postoperative pain following SP-LS, but these results are quite controversial. Some studies have reported that postoperative pain decreases following SP-LS compared with conventional laparoscopic surgery (conventional-LS),^8,11–13 and some studies reported that there were no differences^1,3,4,14 or even an increase in pain.⁷ We suspect that this controversy is due to several confounding factors. In addition, almost all of the previous studies examined the effects in the context of general surgery, and there have been only few data on the effects of SP-LS on postoperative pain in gynecology, even though the procedures performed are different in the two cases.^11,13,14

Therefore, we performed a prospective case-control study to evaluate the effect of SP-LS for benign gynecologic disease and focused specifically on analyzing postoperative pain while minimizing confounding factors. The primary objective of this study was to compare postoperative pain between women who underwent SP-LS (SP-LS group) or conventional-LS (conventional-LS group). The secondary objective was to evaluate the differences in postoperative pain between the SP-LS group and the conventional-LS group based on whether a hysterectomy was performed.

Subjects and Methods

This study was a prospective case-control study performed at Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea, from February 2010 to December 2011. The study was approved by the Hospital's Institutional Review Board.

Study participants were consecutively selected based on pelvic examinations, laboratory tests, and imaging studies including pelvic ultrasonography, computed tomography, or magnetic resonance imaging. The inclusion criteria were as follows: women with a uterus at ≤16 weeks gestational size on pelvic examination and with a main diagnosis of myoma, adenomyosis, endometrial hyperplasia, or preinvasive cervical neoplasia or women with a cystic adnexal mass <10 cm in diameter. Women with a suspected gynecologic malignancy or endometriosis or women who declined participation were excluded.

After the participants were informed of the advantages, disadvantages, and limitations of SP-LS and conventional-LS, they each chose one procedure. The choice of surgical modality was not influenced by the patient's history of previous abdominal surgery and body mass index. Each patient was enrolled prior to the initiation of surgery and provided written informed consent to participate in this study.

We evaluated the patients' characteristics, including age, body mass index, parity, and number of patients with previous abdominal surgery. Additionally, intra- and postoperative outcomes were evaluated, including operative time, transfusion requirements, conversion rates to other procedures, reoperation, intraoperative complications, and hospital stay.

With regard to the operative technique, the port placement system of SP-LS or conventional-LS was established based on our previous reports.^15,16 The technical difference between the two groups was that SP-LS was performed using a transumbilical GelPort (Alexis^®; Applied Medical, Rancho Santa Margarita, CA) and articulating instruments.^15,17 In both groups, on the completion of all surgical procedures, drainage (Evacuator Barovac^®; Sewoon Medical, Seoul) was inserted. Conventional-LS was performed by two expert laparoscopists (J.H.L. and J.S.C.), and SP-LS was performed by one surgeon (J.H.L.).

All patients received postoperative analgesia via continuous intravenous infusion with a continuous infusion device (Ambix ANAPA^®; E-Wha Fresenius Kabi Inc., Seoul). The pain control regimen, consisting of fentanyl, nonsteroidal anti-inflammatory drugs, antiemetics, and normal saline (in a total volume of 100 mL), was delivered at a rate of 2 mL/hour intravenously during a period of 48 hours by a continuous infusion device. Continuous intravenous analgesia began right after the end of the operation. As for additional analgesics, pethidine (25 mg, intravenous injection) was used in the recovery room where the patients were observed for approximately 1 hour, and following that, tramadol (25 mg, intravenous injection every 6 hours) or diclofenac (90 mg, intramuscular injection every 12 hours) was administered by request of the patient and was recorded.

Postoperative pain was evaluated by visual analog scale (VAS) scores and postoperative analgesic use. The VAS (from 0 mm=no pain to 100 mm=maximal pain) scores were measured at 2, 4, 6, 12, 24, 48, and 72 hours after surgery and before the patients were discharged because after 72 hours, ambulation, bowel movement, and returning to a normal life would have more of an effect on postoperative pain rather than the surgery itself. The VAS consisted of a nongraduated 10-cm line range from “no pain” to “pain as bad as it could be.” At the time of each VAS scoring, all patients were asked if they had experienced nausea and/or vomiting.

Statistical analyses

All analyses were performed using Statistical Package for Social Sciences (SPSS) software (version 17.0 for Windows; SPSS Inc., Chicago, IL). Normality testing was conducted using the Kolmogorov–Smirnov test for normality on each variable. The unpaired t test was used to assess the statistical significance of differences observed in the means of the continuous parametric variables. For the nonparametric variables, the Mann–Whitney U test was used. The chi-squared test and Fisher's exact test were used to compare proportions. Values for P<.05 were considered statistically significant.

Results

In total, 399 women who fulfilled both the inclusion and exclusion criteria participated in this study; of these women, 116 were in the SP-LS group, and 283 were in the conventional-LS group. The clinical characteristics and operative results are summarized in Table 1. There were no statistically significant differences between the two groups.

Table 1.

Clinical Characteristics and Operative Data (N=399)

Variable	SP-LS	Conventional-LS	P value
Number of patients	116	283
Age of patient (years)	40.13±10.39	41.26±10.34	.322^a
Body mass index (kg/m²)	22.77±3.88	23.44±3.61	.105^a
Parity	1.17±1.11	1.23±1.15	.669^a
Number of patients with previous abdominal surgery	30 (25.86)	97 (34.26)	.124^b
Surgery performed			.260^c
LAVH	42 (36.21)	119 (42.45)
LAVH with adnexal surgery	7 (6.03)	20 (7.07)
Adnexal surgery	45 (38.80)	79 (27.92)
LM	16 (13.79)	53 (18.73)
LM with adnexal surgery	6 (5.17)	12 (4.24)
Operating time (minutes)	115.55±46.73	118.99±46.72	.504^a
Transfusion (pints)	0.19±0.15	0.15±0.55	.516^a
Conversion to conventional-LS	0 (0)	—
Conversion to laparotomy	0 (0)	0 (0)	1.000^b
Reoperation	0 (0)	0 (0)	1.000^b
Intraoperative complication	1 (0.86)^d	1 (0.35)^d	.497^b
Hospital stay (days)	5.09±2.09	4.95±1.56	.489^a

Data are mean±standard deviation values or number (%)

By unpaired t test.

By Fisher's exact test.

By the Pearson chi-squared test.

Bladder perforation.

Conventional-LS, conventional laparoscopic surgery; LAVH, laparoscopically assisted vaginal hysterectomy; LM, laparoscopic myomectomy; SP-LS, single-port laparoscopic surgery.

Table 2 presents the pain score, the cumulative number of patients administered additional analgesics, and the number of patients with nausea or vomiting at 2, 4, 6, 12, 24, 48, and 72 hours after surgery. Only at 2 hours after surgery was the pain score significantly lower in the SP-LS group (5.70±2.33 compared with 6.38±2.13, P=.005), after which the pain between the two groups did not differ. The cumulative number of patients administered additional analgesics and the number of patients who experienced nausea or vomiting were not different between the two groups at all assessment times.

Table 2.

Postoperative Pain, Analgesic Requirement, Nausea, and Vomiting After Single-Port Laparoscopic Surgery or Conventional Laparoscopic Surgery

	SP-LS	Conventional-LS	P value
Pain score (VAS score) postoperatively
2 hours	5.70±2.33 (116)	6.38±2.13 (283)	.005^a
4 hours	4.40±2.19 (116)	4.82±2.19 (283)	.066^b
6 hours	3.59±1.87 (116)	3.67±2.07 (283)	.938^b
12 hours	2.82±1.45 (116)	2.73±1.79 (283)	.277^b
24 hours	2.12±1.26 (116)	2.10±1.60 (283)	.294^b
48 hours	1.66±1.32 (104)	1.81±1.63 (221)	.861^b
72 hours	1.15±1.08 (24)	1.22±1.38 (78)	.787^b
Cumulative number of patients administered additional analgesics
In the recovery room	47/116 (40.52)	123/283 (43.46)	.656^c
Postoperatively
2 hours	55/116 (47.41)	154/283 (54.42)	.225^c
4 hours	59/116 (50.86)	156/283 (55.12)	.441^c
6 hours	60/116 (51.72)	156/283 (55.12)	.581^c
12 hours	64/116 (55.17)	159/283 (56.18)	.912^c
24 hours	65/116 (56.03)	163/283 (57.60)	.824^c
48 hours	66/116 (56.90)	168/283 (59.36)	.656^c
72 hours	66/116 (56.90)	169/283 (59.72)	.654^c
Number of patients with nausea or vomiting postoperatively
2 hours	16/116 (13.79)	41/283 (14.89)	1.00^c
4 hours	4/116 (3.45)	11/283 (3.89)	1.000^c
6 hours	5/116 (4.31)	16/283 (5.65)	.805^c
12 hours	6/116 (5.17)	14/283 (4.95)	1.000^c
24 hours	11/116 (9.48)	23/283 (8.13)	.694^c
48 hours	1/104 (0.96)	10/221 (4.52)	.184^c
72 hours	0/24 (0.00)	0/78 (0.00)	1.000^c

Data are number of patients/number of patients observed (%).

By unpaired t test.

By Mann-Whitney U test.

By Fisher's exact test.

Conventional-LS, conventional laparoscopic surgery; SP-LS, single port laparoscopic surgery; VAS, visual analog scale.

In terms of the postoperative pain, Table 3 presents the differences between the SP-LS group and the conventional-LS group based on whether a hysterectomy was performed. Of the 188 of the total of 399 patients who underwent surgery that included laparoscopically assisted vaginal hysterectomy (LAVH), 49 patients underwent surgical intervention with SP-LS, and 139 patients underwent surgical intervention with conventional-LS. There were no differences in the pain score comparing the surgical method used (SP-LS or conventional-LS) when analyzing the postoperative pain for these 188 patients only. Patients who underwent surgery without LAVH included 211 of the total of 399 patients. Of these, 67 patients underwent SP-LS, and 144 patients underwent conventional-LS. When the postoperative pain was analyzed for these 211 patients alone, the pain score was significantly lower in patients who underwent SP-LS only at 2 hours postoperatively (5.33±2.01 compared with 6.05±1.96, P=.016). In addition, we compared the pain scores depending on whether LAVH was performed or not in the SP-LS and conventional-LS groups. In the SP-LS group, the pain score at 2 hours postoperatively was higher in patients who underwent surgery including LAVH than in those who underwent surgery that did not include LAVH (6.21±2.58 compared with 5.33±2.01, P=.046), but there were no differences after 2 hours. In the conventional-LS group, the pain score at 2 and 4 hours postoperatively was high in patients who underwent surgery including LAVH (6.72±2.26 compared with 6.05±1.96 [P=0.008] and 5.19±2.30 compared with 4.46±2.02 [P=.005], respectively).

Table 3.

Comparison of Pain Score According to Whether a Hysterectomy Was Performed

	Surgery including LAVH (n=188)			Surgery not including LAVH (n=211)
Postoperatively	SP-LS	Conventional-LS	P value	SP-LS	Conventional-LS	P value
2 hours	6.21±2.58 (49)	6.72±2.26 (139)	.192^a	5.33±2.01 (67)	6.05±1.96 (144)	.016^a
4 hours	4.57±2.42 (49)	5.19±2.30 (139)	.110^a	4.27±2.01 (67)	4.46±2.02 (144)	.526^a
6 hours	3.65±1.90 (49)	3.79±2.17 (139)	.700^a	3.54±1.85 (67)	3.55±1.97 (144)	.970^a
12 hours	2.79±1.43 (49)	2.87±1.93 (139)	.764^a	2.84±1.47 (67)	2.61±1.64 (144)	.103^b
24 hours	2.18±1.39 (49)	1.93±1.49 (139)	.219^b	2.08±1.16 (67)	2.27±1.69 (144)	.843^b
48 hours	1.64±1.20 (45)	1.83±1.56 (112)	.915^b	1.67±1.41 (59)	1.76±1.54 (109)	.852^b
72 hours	0.71±0.46 (9)	1.26±1.43 (47)	.486^b	1.41±1.27 (15)	1.17±1.32 (31)	.563^a

	SP-LS (n=116)			Conventional-LS (n=283)
Postoperatively	Surgery including LAVH	Surgery not including LAVH	P value	Surgery including LAVH	Surgery not including LAVH	P value
2 hours	6.21±2.58 (49)	5.33±2.01 (67)	0.046^a	6.72±2.26 (139)	6.05±1.96 (144)	.008^a
4 hours	4.57±2.42 (49)	4.27±2.01 (67)	0.474^a	5.19±2.30 (139)	4.46±2.02 (144)	.005^a
6 hours	3.65±1.90 (49)	3.54±1.85 (67)	0.756^a	3.79±2.17 (139)	3.55±1.97 (144)	.344^a
12 hours	2.79±1.43 (49)	2.84±1.47 (67)	0.874^a	2.87±1.93 (139)	2.61±1.64 (144)	.198^b
24 hours	2.18±1.39 (49)	2.08±1.16 (67)	0.911^b	1.93±1.49 (139)	2.27±1.69 (144)	.129^b
48 hours	1.64±1.20 (45)	1.67±1.41 (59)	0.798^b	1.83±1.56 (112)	1.76±1.54 (109)	.777^b
72 hours	0.71±0.46 (9)	1.41±1.27 (15)	0.131^a	1.26±1.43 (47)	1.17±1.32 (31)	.655^b

Data are mean±standard deviation values (number of patients scored).

Conventional-LS, conventional laparoscopic surgery; LAVH, laparoscopically assisted vaginal hysterectomy; SP-LS, single-port laparoscopic surgery.

By unpaired t test.

By Mann–Whitney U test.

Discussion

The reduction in pain after surgery allows for earlier discharge, reduction in analgesic consumption, faster recovery, and an earlier return to work.^9,10 Therefore, reduced postoperative pain, one of the potential benefits of SP-LS, has clinically significant importance. However, the studies associated with the effects of SP-LS on postoperative pain are sparse and controversial.^{1,3,4,11,13,14,18}

The results from previous studies analyzing the effects of SP-LS on postoperative pain are summarized in Table 4. We suspect that the controversial inconsistencies with regard to the effects of SP-LS on postoperative pain (shown in Table 4) are due to the following confounding factors: (1) difference in the postoperative pain control methods (patient-controlled analgesia, intermittent injections of analgesia, etc.); (2) the type of procedures performed (hysterectomy, adnexectomy, cholecystectomy, colectomy, etc.); (3) the use of postoperative drainage^19,20; and (4) the type of port placement system used for SP-LS. We used a postoperative closed drainage and continuous intravenous analgesics for all patients to minimize these possible confounders and evaluated postoperative pain depending on whether a hysterectomy was performed.

Table 4.

Summary of Previous Studies Investigating the Effect of Single-Port Laparoscopic Surgery on Postoperative Pain

Reference (year)	Study design	Sample (n)	Procedure performed	Time used to check for pain	Use of single-port system	Use of drainage	Method for pain control (type of analgesics)	Effect of SP-LS on postoperative pain
Chen et al.¹¹ (2011)	Prospective randomized trial	SP-LS: 50C-LS: 50	LAVH	TAO in 12, 24, and 48 hours	Glove port system	NM	Analgesics as required (meperidine, tenoxicam)	Decreased
Champagne et al.⁸ (2012)	Prospective matched case-controlled study	SP-LS: 165C-LS: 165	Colectomy	TAO in 24 hours	NM	NM	NM	Decreased
Lee et al.¹² (2012)	Prospective randomized trial	SP-LS: 39C-LS: 49	Varicocele ligation	TAO in 24, 48, and 72 hours	Glove port system	Not used	Analgesics as required (morphine equivalent)	Decreased
Fagotti et al.¹³ (2011)	Prospective randomized trial	SP-LS: 30C-LS: 30	Adnexal surgery	TAO in 0.3, 2, 4, and 6 hours	Single multiport trocar (Olympus Winter and IBE)	Not used	Analgesics as required (acetaminophen)	Decreased
Joseph et al.¹ (2011)	Retrospective study	SP-LS: 108C-LS: 177	Cholecystectomy	TAO in 0–8 hours	A single 2-cm umbilical skin incision and three separate fascial incisions	NM	Analgesics as required (morphine equivalent)	No significant differences
Cao et al.⁴ (2011)	Prospective randomized trial	SP-LS: 57C-LS: 51	Cholecystectomy	TAO in 24 and 72 hours	A single 2-cm umbilical skin incision and three separate fascial incisions	Not used	Analgesics as required (NM)	No significant differences
Afaneh et al.³ (2010)	Prospective randomized trial	SP-LS: 50C-LS: 50	Donor nephrectomy	At discharge from hospital	GelPoint	NM	Regular intravenous NSAIDs and analgesics as required (morphine, oral narcotics)	No significant differences
Jung et al.¹⁴ (2011)	Prospective randomized trial	SP-LS: 30C-LS: 34	TLH	TAO in 6, 24, 48, and 72 hours	Glove port system	NM	Analgesics as required (pethidine, NSAIDs)	No significant differences
Phillips et al.⁷ (2012)	Prospective randomized trial	SP-LS: 117C-LS: 80	Cholecystectomy	TAO in 0–30 days	SILS port system¹⁹	NM	Analgesics as required (NM)	Increased
Present study	Prospective case-controlled study	SP-LS: 116C-LS: 283	Surgery for gynecologic disease	TAO in 2, 4, 6, 12, 24, 48, and 72 hours	GelPort	Always used	Continuous intravenous infusion and as required (pethidine, tramadol, NSAIDs)	No significant differences

C-LS, conventional laparoscopic surgery; LAVH, laparoscopically assisted vaginal hysterectomy; NM, not mentioned; NSAIDs, nonsteroidal anti-inflammatory drugs; SP-LS, single-port laparoscopic surgery; TAO, time after operation; TLH, total laparoscopic hysterectomy.

When comparing the SP-LS group and the conventional-LS group (Table 2), regardless of whether a hysterectomy was performed, the VAS score was low (P=.005) only at 2 hours postoperatively in the SP-LS group, and there were no differences after 2 hours. In addition, there was no difference in the cumulative number of patients administered additional analgesics or the number of patients who experienced nausea or vomiting between the groups. We were able to formulate the following hypotheses from these results: (1) the effect of SP-LS on postoperative pain is not favorable except in the immediate postoperative state (2 hours following operation) compared with conventional-LS, and (2) even if there is a difference in postoperative pain between SP-LS and conventional-LS, the difference in pain can be compensated for by use of a proper pain control method. Although continuous intravenous analgesics were administered to all patients in this study, we concluded that the continuous analgesics used were ineffective because over half of the patients (56.90% in the SP-LS group and 59.72% in the conventional-LS group) received additional analgesics. Based on this result, we conclude that the first hypothesis was more convincing. To determine which hypothesis is true, it would be necessary to conduct a large prospective randomized study that compares postoperative pain without performing pain control; however, this approach is not possible because of ethical concerns. In addition, the significance of the difference in the observed VAS (0.5) is questionable.

In the field of gynecology, unlike adnexal surgery, myomectomy, etc., hysterectomy inevitably includes a vaginal incision accompanied with a destruction of pelvic structures. Even if SP-LS has the effect of decreasing postoperative pain induced by abdominal incision, it has no effect on the postoperative pain caused by the vaginal stump and pelvic structures. Therefore, there may be a difference in the effect of SP-LS on postoperative pain when comparing patients who underwent surgery with or without a hysterectomy. To evaluate this clearly, we divided the patients into subgroups based on whether a hysterectomy was performed and compared the subgroups. As seen in Table 3, in surgeries that did not include a hysterectomy, pain for SP-LS was only reduced during the immediate postoperative state (2 hours postoperatively), whereas a reduction in pain was not observed in surgeries that included a hysterectomy. These results present the possibility that SP-LS may have no effect in reducing the pain caused by the vaginal stump and destruction of pelvic structures and that these types of pain may be dominant over the pain associated with an abdominal incision. However, it can be concluded that there was no effect on pain reduction after SP-LS in patients who underwent surgery that included a hysterectomy.

A comparison of results from other groups and those presented in the current study (with regard to postoperative pain following SP-LS) is summarized in Table 4. Except for the studies of Joseph et al.¹ and Cao et al.,⁴ most studies used the Alexis wound retractor as the base for the port placement system in SP-LS. The Alexis wound retractor provides maximum exposure with minimum incision size²¹ but can increase the postoperative wound pain because of the requirement to provide continuous compression to the incision site during surgery. Therefore, there is a chance that this study is influenced by use of the wound retractor; however, further analysis is needed to confirm this possibility. The effect of the use of postoperative drainage could not be determined because it was not mentioned in any studies except the present study. After surgery, postoperative drainage reduces pain caused by peritoneal irritation by removing pneumoperitoneum and relieves pain by releasing collected fluid containing cytokines produced by an inflammatory reaction.^19,20 Therefore, by performing postoperative drainage in both the SP-LS and conventional-LS groups in this study, the use of postoperative drainage was not a confounding factor in this study.

There are multiple strengths to the approach used in this study. First, this is a prospective control study with a relatively large number of patients. Second, there is no interoperator bias because a single surgeon performed the SP-LS surgery. Third, the possible confounding effects were minimized. On the other hand, we acknowledge the potential limitations of the current study. First, only LAVH was performed among various types of laparoscopic hysterectomies (LAVH, total laparoscopic hysterectomy including laparoscopic supracervical hysterectomy, etc.). Second, a GelPort with a wound retractor base was used as the port placement system for SP-LS. Therefore, the results of this study cannot be generally applied to cases in which different types of hysterectomies are performed or different types of port placement systems are used.

In conclusion, SP-LS results in less postoperative pain than conventional-LS only in the immediate postoperative state for patients who underwent surgery that did not include a hysterectomy. On the other hand, there is no difference in the postoperative pain between the SP-LS and conventional-LS groups when patients underwent surgery that included a hysterectomy. However, a large prospective randomized study is needed to confirm this conclusion as well as for SP-LS to become a preferred approach that is used in the field of gynecology.

Footnotes

Disclosure Statement

No competing financial interests exist.

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