A Meta-analysis of Randomized Clinical Trials That Compared Ultrasonic Energy and Monopolar Electrosurgical Energy in Laparoscopic Cholecystectomy

Abstract

Background:

Currently, monopolar electrical energy is still widely used as the main source of energy for laparoscopic cholecystectomy (LC). However, some studies have suggested that the use of ultrasonic energy is more advantageous. This meta-analysis pooled the currently published randomized controlled trials comparing the safety and efficacy of ultrasonic energy and monopolar electrical energy in LC.

Materials and Methods:

MEDLINE, EMBASE, Science Citation Index Expanded, and the Cochrane Central Register of Controlled Trials for relevant articles published between January 1985 to February 2012 by using the search terms “laparoscopic cholecystectomy,” “electrocoagulation,” “electrosurgery,” “ultrasonics,” “ultrasonic therapy,” and “dissection.” Intraoperative and postoperative measures and complications were evaluated.

Results:

Eight high-quality randomized controlled trials with 1056 patients were included. Differences in mean operation time, mean blood loss, mean hospital stay, gallbladder perforation, and postoperative abdominal pain score at 24 hours were statistically significant between the two groups, in favor of the use of ultrasonic energy. However, there were no differences in operation conversion, bile leakage, intra-abdominal collections, and postoperative nausea at 24 hours.

Conclusions:

Ultrasonic energy is as safe and effective as electrosurgical energy and potentially might be safer in LC. However, the financial implications of this technical modality need to be established in cost-effectiveness analysis.

Introduction

Since Muhe and co-workers performed the first successful laparoscopic cholecystectomy (LC) in 1985,¹ this procedure has become the gold standard for treatment of symptomatic cholelithiasis, with several advantages over open surgery in terms of less pain, faster rehabilitation, and less prominent scars.² Currently, monopolar electrosurgical energy is the most commonly used energy undertaken for surgery in LC. However, its application is associated with numerous risks, such as biliary compilations and thermal injuries.³ Ultrasonic energy, on the other hand, involves the application of ultrasound within the harmonic frequency range, which limits lateral energy spread, hence reducing the risk of distant tissue damage compared with high-frequency electrosurgery.⁴ It has therefore been suggested as an alternative to electrosurgical energy.⁵ The current evidence, based on a large number of comparative studies, reveals inconsistent results. So it is necessary to investigate the safety and efficacy of these two energies in the setting of LC by meta-analysis.

Materials and Methods

Literature search

A comprehensive literature search of MEDLINE, EMBASE, Science Citation Index Expanded, and the Cochrane Central Register of Controlled Trials in The Cochrane Library between January 1985 and February 2012 (since the first LC was reported in 1985) was carried out for comparing ultrasonic energy and monopolar electrical energy in LC. The medical subject headings “laparoscopic cholecystectomy,” “electrocoagulation,” “electrosurgery,” “ultrasonics,” “ultrasonic therapy, and “dissection” were used. Equivalent free-text search terms were used in the search strategy. All abstract supplements from published literature were searched manually. Relevant articles were also identified from the reference lists of previous publications, including those obtained through the search of abstracts and recent international meetings. Moreover, investigators and experts in the field of laparoscopic surgery were contacted to ensure that all relevant studies were identified. Only randomized clinical trials (RCTs) with full-text descriptions were included. Final inclusion of articles was determined by consensus (J.J.X., K.A.); when this failed, a third author (M.A.J.) adjudicated.

Inclusion criteria

Two authors (J.J.X., K.A.) identified and screened the search findings for potentially eligible RCTs. To enter our analysis, studies had to meet the following criteria: (1) English language articles published in peer-reviewed journals; (2) human trials; (3) studies with at least one of the outcomes mentioned; and (4) when similar studies were reported by the same institution, either the better-quality study or the more recent publication was included.

Exclusion criteria

The following studies were not considered for meta-analysis: (1) abstracts, letters, editorials, expert opinions, reviews, and case reports; (2) no outcome measure reported; (3) RCTs comparing two energies in either arm rather than ultrasonic energy versus monopolar electrical energy; and (4) studies with laparoscopic subtotal cholecystectomy.

Outcomes of interest and definition

Intraoperative and postoperative outcomes and complications were evaluated. Mean operation time was defined as time from skin incision to skin closure. Mean blood loss was described as blood loss reported from the beginning to the end of the operation. Mean hospital stay was described as either the mean number of days during which patients stayed in hospital or the mean number of patients who needed overnight hospital stay for particular reasons. Operation conversion was considered to have occurred when LC was switched to an open procedure or when an endoscopic procedure was added. Gallbladder perforation was defined as leak of bile alone or with loss of stones or both through an opening from the gallbladder into the peritoneal cavity. Bile leakage was defined as bile observed in the subhepatic drain during the postoperative stage for a certain period of time. Intra-abdominal collections were confirmed with either computed tomography or abdominal ultrasound. Postoperative abdominal pain score at 24 hours was evaluated using a 10-point visual analog scale.⁶ Postoperative nausea was also assessed at 24 hours.

Data extraction and quality assessment

Data were extracted by two independent observers (W.H. and R.M.) using standardized forms. The recorded data included the population characteristics, surgical techniques, follow-up time, and outcome parameters. Standard deviation (SD) was obtained directly or indirectly through calculating from mean and standard error or 95% confidence interval (CI). The quality of all selected trials was assessed using the scoring system of Jadad et al.⁷ Allocation concealment, blinding of outcome assessors, and reporting of an intention-to-treat analysis were also assessed. As is true for any study investigating surgical procedure, double blinding was not feasible, and therefore all trials received no points for this. A study was considered to be high quality if the Jadad score was ≥3.

Statistical analysis

Meta-analysis was performed by using Review Manager version 5.0 software (The Cochrane Collaboration, Oxford, UK). For continuous variables, treatment effects were expressed as weighted mean difference (WMD) with corresponding 95% CI. For categorical variables, treatment effects were expressed as odds ratio (OR) with corresponding 95% CI. Meta-analysis was performed using fixed-effect or random-effect methods, depending on the absence or presence of significant heterogeneity. However, the fixed-effects model was initially calculated for all outcomes.⁸ Heterogeneity was evaluated using the chi-squared test, with a P value of <0.1 considered significant; I² values were used for the evaluation of statistical heterogeneity.⁹ If the test rejected the assumption of homogeneity of studies, then the random-effects analysis was performed.¹⁰ Sensitivity analyses were also performed by removing individual studies from the dataset and analyzing the effect on the overall results to identify sources of significant heterogeneity. Funnel plots were constructed to evaluate potential publication bias.¹¹

Results

Description of included RCTs

The search strategy initially generated 236 relevant clinical trials. Through reading the title and abstract, 17 RCTs were selected for further investigation.^12–28 Of these, two studies did not provide the required data,^23,24 one study included laparoscopic subtotal cholecystectomy as well,²⁵ and three studies made inappropriate comparison.^26–28 In total, 11 RCTs with 1434 patients fulfilled the outlined criteria.^12–22 Figure 1 shows the process of selecting RCTs using PRISMA criteria.²⁹ Eight studies were found to be of high quality (Jadad score=3) and had adequate allocation concealment.^{12,15–20,22} Only these were included in the final analyses. However, sensitivity analyses were undertaken including the low-quality trials to ascertain the effect on the pooled estimate. The study characteristics and Jadad score of the included RCTs are shown in Table 1. The defined outcome variables extracted from all the studies are shown in Table 2.

FIG. 1.

Flow diagram depicting the study selection process in accordance with PRISMA guidelines.²⁹

Table 1.

Characteristics of the Included (High- and Low-Quality) Randomized Clinical Trials

Reference	Country	Year	Patients (n)	Analyzed (n)	U	E	Laparoscopic techniques	Follow-up	Jadad score
Wetter et al.¹²	United States	1992	73	58	37	21	—	1 month	3
Tsimoyiannis et al.¹³	Greece	1998	200	200	100	100	FT; PP (–)	—	2
Sietses et al.¹⁴	The Netherlands	2001	18	18	9	9	FT; PP (–)	—	2
Janssen et al.¹⁵	The Netherlands	2003	200	199	96	103	FT; PP (15 mm Hg)	—	3
Cengiz et al.^{16 a}	Sweden	2005	80	73	40	33	FT; PP (<10 mm Hg)	1 month	3
Bessa et al.¹⁷	Egypt	2008	120	120	60	60	FT; PP (15 mm Hg)	6 months	3
El Nakeeb et al.¹⁸	Egypt	2010	120	120	60	60	FT; PP (14 mm Hg)	6 months	3
Kandil et al.¹⁹	Egypt	2010	140	140	70	70	FT; PP (12 mm Hg)	6 months	3
Cengiz et al.^{20 a}	Sweden	2010	243	154	73	81	FT; PP (<12 mm Hg)	1 month	3
Redwan²¹	Egypt	2010	160	160	80	80	U-2T; E-3T; PP (–)	Until discharge	2
Jain et al.²²	India	2011	200	192	96	96	FT; PP (–)	6 months	3

In these studies, ultrasonic fundus-first dissection was used.

2T, two-trocar; 3T, three-trocar; E, electrocautery; FT, four-trocar; PP, pneumoperitoneum pressure; U, ultrasonic dissection.

Table 2.

Outcomes of All the Randomized Clinical Trials

Reference	Group	Mean operation time (minutes)	Mean hospital stay (days)	Mean blood loss (mL)	Operation conversion	Gallbladder perfusion	Bile leakage	Intra-abdominal fluid collections	Postoperative abdominal pain score at 24 hours	Postoperative nausea at 24 hours
Wetter et al.¹²	U E	90±0	1.4±0	>10 mL (1^a)	NA	NA	NA	NA	NA	NA
		97±0	1.1±0	>10 mL (4^a)	NA	NA	NA	NA	NA	NA
Tsimoyiannis et al.¹³	U	37±9	1.6±0.7	2±1.8	NA	NA	0/100	1/100	1.64±1.11	20/100
	E	45±7	1.9±0.8	14±9	NA	NA	3/100	5/100	1.61±1.2	22/100
Sietses et al.¹⁴	U	51±18	2±0	NA	0/9	NA	NA	NA	NA	NA
	E	57±42	2±0	NA	0/9	NA	NA	NA	NA	NA
Janssen et al.¹⁵	U	60±0	NA	NA	NA	15/96	NA	NA	NA	NA
	E	65±0	NA	NA	NA	51/103	NA	NA	NA	NA
Cengiz et al.¹⁶	U	46±2.04	2±0	NA	3/43	NA	0/40	NA	1.5±0.25	2/40
	E	61±3.06	8±0	NA	4/37	NA	1/33	NA	2.6±0.30	4/33
Bessa et al.¹⁷	U	32±0	1±0	NA	0/60	6/60	0/60	NA	NA	NA
	E	40±0	1±0	NA	0/60	20/60	0/60	NA	NA	NA
El Nakeeb et al.¹⁸	U	45.17±10.54	0.91±0.18	70.13±80.79	2/60	6/60	1/60	3/60	3.07±2.02	NA
	E	69.71±13.01	1.44±0.71	133±131.13	3/60	11/60	2/60	7/60	4.4±2.11	NA
Kandil et al.¹⁹	U	33.21±9.62	0.98±0.10	43.28±31.27	0/70	5/70	0/70	2/70	3.12±1.64	16/70
	E	51.7±13.79	1.12±0.37	83.31±46.23	2/70	13/70	2/70	1/70	4.48±1.89	24/70
Cengiz et al.²⁰	U	NA	NA	12±2.55	1/77	19/73	NA	NA	NA	NA
	E	NA	NA	53±7.14	0/81	37/81	NA	NA	NA	NA
Redwan²¹	U	16.8±6.8	1.00±0	NA	0/80	NA	1/80	0/80	NA	NA
	E	44.01±6.47	1.53±0.51	NA	0/80	NA	1/80	0/80	NA	NA
Jain et al.²²	U	50±9.36	1.89±0.56	NA	4/100	9/96	0/96	NA	1.86±0.76	NA
	E	64.70±13.74	2.52±0.75	NA	4/100	18/96	0/96	NA	3.01±0.86	NA

Number of patients.

E, electrocautery; NA, data not available; U, ultrasonic group.

Patient characteristics

Most of the patients recruited in the included RCTs had symptomatic gallstone disease^15,17,18,22 or were scheduled for LC.^12,15,16,20 Patients with acute cholecystitis,^15,17,22 common bile duct stones,^15,17–21 and those with history of previous abdominal operations^15,17–20 were excluded from various studies. Some trials also excluded patients with extreme obesity,²⁰ more than 80 years old,^18,19 with suspicion of gallbladder malignancy,^15,17,22 and with acute pancreatitis.^20,22 It is notable that all patients included in one¹⁸ of the studies and some patients in another¹⁹ had cirrhosis; therefore, sensitivity analyses were undertaken by excluding these studies.

Surgical technique and equipment

Although different terms were used in different studies to describe various devices used for undertaking ultrasonic dissection, such as ultrasonic shears, Harmonic™ (Ethicon Endo-Surgery) scalpel, ultrasonically activated coagulating shears, UltraCision™ (Ethicon Endo-Surgery) Harmonic shears, and cavitron ultrasonic surgical aspirator, the basic mechanism of ultrasonic coagulation is the same with all these devices. In the study by Wetter et al.,¹² a laser energy was used in a separate group (n=15); therefore, data pertaining to these patients were excluded from the analysis. In the study by Cengiz et al.²⁰ in 2010, three comparison groups—conventional electrocautery, fundus-first electrocautery, and fundus-first ultrasonic dissection—were used. In order to minimize any bias that a different operating technique might introduce, data from only the two fundus-first groups were analyzed for all the outcome measurements. As antegrade cholecystectomy rather than fundus-first dissection was used in most of the studies, a sensitivity analysis was undertaken excluding these trials^16,20 for all the included outcome measures, to ascertain any bias that a different technique might bring within the analyses. Most of the studies excluded patients from the final analysis if their procedure was converted to open cholecystectomy. These specific data were only used for undertaking the conversion rate analysis.^16,20,22

Meta-analysis results

Results of the analysis are shown in Figure 2 and Table 3.

FIG. 2.

(A–I) Forest plots illustrating results of all meta-analysis (high-quality trials only) comparing ultrasonic energy with monopolar electrical energy. Test for heterogeneity: chi-squared statistic with its degrees of freedom (df) and P value. Inconsistency among results: I² test for overall effect; Z statistic with P value. A fixed-effects or random-effects model was used. IV, inverse variance; CI, confidence interval; M-H, Mantel–Haenszel; OR, odds ratio; SD, standard deviation; WMD, weighted mean difference.

Table 3.

Meta-Analysis of Outcomes of Interest

Outcome of interest	Number of studies	Number of patients	Type	WMD/OR (95% CI)	P value	Heterogeneity P value	I² (%)
High-quality studies
Mean operating time	7^{12,15–19,22}	902	Random	−17.86 (−21.72 to −14.01)	<.00001	.0002	85
Mean blood loss	3^18–20	414	Fixed	−41.02 (−42.67 to −39.38)	< .00001	.54	0
Mean hospital stay	6^{12,16–19,22}	703	Random	−0.43 (−0.76 to −0.09)	.01	< .00001	93
Operation conversion	6^16–20,22	818	Fixed	0.75 (0.33–1.67)	.48	.78	0
Gallbladder perfusion	6^{15,17–20,22}	925	Fixed	0.31 (0.22–0.44)	< .00001	.45	0
Bile leakage	5^16–19,22	645	Fixed	0.31 (0.06–1.56)	.16	.89	0
Intra-abdominal fluid collections	2^18,19	260	Fixed	0.61 (0.19–1.91)	.39	.25	23
Postoperative abdominal pain score at 24 hours	4^16,18,19,22	525	Fixed	−1.13 (−1.23 to −1.02)	< .00001	.78	0
Postoperative nausea at 24 hours	2^16,19	213	Fixed	0.53 (0.27–1.06)	.07	.68	0
Subgroup analysis (all studies)
Mean operating time	10^{12–19,21,22}	1280	Random	−17.57 (−23.33 to −11.80)	< .00001	< .00001	97
Mean blood loss	4^13,18–20	614	Random	−35.52 (−57.05 to −13.99)	.001	< .00001	99
Mean hospital stay	9^{12–14,16–19,21,22}	1081	Random	−0.39 (−0.65 to −0.14)	.002	< .00001	90
Operation conversion	8^14,16–22	996	Fixed	0.75 (0.33 to 1.67)	0.48	0.78	0
Gallbladder perfusion	6^{15,17–20,22}	925	Fixed	0.31 (0.22 to 0.44)	< .00001	.45	0
Bile leakage	7^{13,16–19,21,22}	1005	Fixed	0.38 (0.12 to 1.23)	.11	.68	0
Intra-abdominal fluid collections	4^13,18,19,21	620	Fixed	0.44 (0.16 to 1.19)	.11	.35	5
Postoperative abdominal pain score at 24 hours	5^{13,16,18,19,22}	725	Random	−0.95 (−1.40 to −0.50)	< .0001	< .00001	91
Postoperative nausea at 24 hours	3^13,16,19	413	Fixed	0.69 (0.43–1.11)	.13	.54	0

CI, confidence interval; OR, odds ratio; WMD, weighted mean difference.

Mean operation time

Mean operation time was examined in all eight studies, but one was excluded as the SD of operation time was not available.²⁰ The pooled analysis showed a significantly shorter mean operation time in the ultrasonic energy group (WMD, −17.86; 95% CI, −21.72 to −14.01; P<.00001). Inclusion of low-quality trials showed a similar effect (WMD, −17.57; 95% CI, −23.33 to −11.80; P<.00001).

Mean blood loss

Four studies^12,18–20 reported the mean blood loss during the operation. One study¹² was excluded as it only stated the number of patients who experienced blood loss of more than 10 mL. The pooled estimate showed a statistically significant reduction in the outcome measure using ultrasonic energy (WMD, −41.02; 95% CI, −42.67 to −39.38, P<.00001). No significant difference in the result was seen with inclusion of a low-quality trial (WMD, −35.52; 95% CI, −57.05 to −13.99, P=.001).

Mean hospital stay

Mean hospital stay was reported in six RCTs.^{12,16–19,22} The overall effect suggested a significant reduction of mean hospital stay in the ultrasonic energy group (WMD, −0.43; 95% CI, −0.76 to −0.09, P=.01). This beneficial effect was maintained even when low-quality trials were included (WMD, −0.39; 95% CI, −0.65 to −0.14), P=.002).

Operation conversion

Six studies^16–20,22 reported the number of operation conversions. No statistically significant difference was found between the two groups (OR, 0.75; 95% CI, 0.33–1.67; P=.48). The addition of low-quality studies did not have an effect on the pooled estimate.

Gallbladder perforation

Gallbladder perforation was described in six studies.^{15,17–20,22} The pooled result favored the ultrasonic dissection (OR, 0.31; 95% CI, 0.22–0.44; P<.00001). The addition of low-quality studies did not have an effect on the pooled estimate.

Bile leakage

The pooled estimate from five studies^16–19,22 revealed that use of ultrasonic dissection significantly reduced the incidence of bile leakage (OR, 0.31; 95% CI, 0.06–1.56; P=.16). Sensitivity analysis with inclusion of low-quality studies showed similar results (OR, 0.38; 95% CI, 0.12–1.23; P=.11).

Intra-abdominal collections

Two studies^18,19 reported this outcome measure and found no difference in the incidence with the use of either of the energy modalities (OR, 0.61; 95% CI, 0.19–1.91; P=.39). The effect was not improved when low-quality studies were included (OR, 0.44; 95% CI, 0.16–1.19; P=.11).

Postoperative abdominal pain at 24 hours

Postoperative abdominal pain scores were reported in four trials.^16,18,19,22 Ultrasonic energy resulted in a significant reduction in postoperative abdominal pain (WMD, −1.13; 95% CI, −1.23 to −1.02; P<.0001). This positive effect persisted even when low-quality trials were included (WMD, −0.95; 95% CI, −1.40 to −0.50; P<.0001).

Postoperative nausea at 24 hours

Two studies^16,19 reported the number of patients who experienced postoperative nausea at 24 hours. The pooled estimate indicated that the outcome measure was not affected by the type of energy used (OR, 0.53; 95% CI, 0.27–1.06; P=.07). The result did not change when a low-quality study was included for sensitivity analysis (OR, 0.69; 95% CI, 0.43–1.11; P=.13).

Sensitivity and subgroup analysis

As mentioned above, subgroup analyses were undertaken for each outcome measure by including all trials (including low-quality studies) to ascertain the effect on the pooled estimate. No difference was found for any of the reported outcome measures (Table 3) (see Supplementary Fig. S1 [Forest plot in subgroup analyses]; Supplementary Data are available online at www.liebertpub.com/lap). Sensitivity analyses were also performed by excluding trials that used the fundus-first technique^16,20 and trials that included patients with cirrhosis.¹⁸ These exclusions did not alter the results obtained from cumulative analyses.

Publication bias

Publication bias was investigated using funnel plots. These depicted basic symmetry for all the outcomes (data not shown). Therefore, there was no evidence of publication bias in this analysis.

Discussion

Monopolar electrosurgery and ultrasonic energy are the two most frequently used energy forms to achieve adequate dissection and hemostasis in LC. Traditionally, monopolar electrocautery energy has been routinely used because of lower cost and ease of use for securing hemostasis. However, it can produce more smoke, leading to unclear operation vision, and is unselective for cutting fibrous tissues, which can increase the biliary complications and thermal injuries.⁴ In recent years, ultrasonic energy has been introduced for LC as an alternative and has gained much attention. Amaral³⁰ suggested that the ultrasonic energy is a safe and effective energy form that could replace monopolar electrosurgery in human laparoscopic surgery. The results from this meta-analysis indicate that the use of ultrasonic dissection not only achieves an improvement in the performance of LC, but also leads to fewer postoperative complications and a shorter recovery time.

We found a significant reduction in mean operation time and mean blood loss with the use of ultrasonic dissection compared with electrocautery, even when it was used in complicated patients.¹⁹ Although operating time is regarded as largely dependent on the training and expertise of individual surgeons, Janssen et al.¹⁵ showed that there was no difference in the operation time when the procedure was accomplished by an experienced surgeon or by a resident. Therefore, the shorter operating time associated with ultrasonic dissection could be the result of an improved laparoscopic view, an uncomplicated course of the procedure without bile or stone loss, and a reduced number of lens cleanings.^16,31 Also, clearer operation vision and optimal hemostasis³² afforded by ultrasonic dissection could avoid accidental injury of small blood vessels, thus reducing mean blood loss.

Gallbladder perforation, postoperative abdominal pain, and mean hospital stay were found to be significantly reduced by ultrasonic dissection. Reduced gallbladder perforation can be explained by the fact that ultrasonic dissection can reduce the smoke formation, resulting in significantly clearer operation vision. Moreover, this lower gallbladder perforation rate may be attributed to the effectiveness of the ultrasonic dissection with minimal lateral thermal tissue damage, minimal charring, and desiccation.²³ The level of surgical experience did not affect gallbladder perforation when ultrasonic dissection was used comparing with electrocautery.¹⁵ Greater postoperative pain experienced by patients undergoing LC with electrocautery could be due to greater number of incisions,³³ high intra-abdominal pressure during surgery,³⁴ and bile leakage from the liver bed.³⁵ The statistically significant reduction seen in our analysis on the postoperative abdominal pain with ultrasonic energy may be attributed to one or more of these factors, in addition to a decrease in amount of bile present in peritoneum, which could be due to perforation of the gallbladder. In keeping with this, hospital stay was also found to be reduced with the use of ultrasonic dissection compared with electrocautery in LC, likely to be because of the overall reduction in complications with the use of ultrasonic dissection.

The frequency of conversion to open cholecystectomy was not found to be statistically significant between the two groups. The current literature reports a figure of 5%–10% for the conversion rate of the procedure.^36,37 Situations that might require a conversion include bleeding, acute cholecystitis with severe abdominal adhesions, common bile duct injury, and choledocholithiasis.^37–39 Moreover, Sakpal et al.³⁷ pointed toward a possible impact of surgeon experience on the incidence of conversion. It is entirely possible that ultrasonic energy does not affect the conversion and that it is the characteristics of a patient's disease and surgeon's experience that determine the rate of conversion.

Bile leak is a potential complication of LC, and the cystic duct stump is the most common site of leakage. In the absence of an injury to either the common bile duct or cystic duct, the leak may originate from the gallbladder bed or duct of Luschka, previously shown to be effectively controlled by use of ultrasonic dissection in studies by Westervelt³⁵ and Kavlakoglu et al.⁴⁰ In our study, the incidence of bile leakage was not found to be statistically different between the two groups. Intra-abdominal fluid collections and postoperative nausea at 24 hours were also not found to be statistically different between the two groups. Thus, these two outcomes could be further investigated as only a few studies included these data in our meta-analysis, although the weight of evidence here in favor of ultrasonic dissection is evident from other parameters.

In summary, we have established a possible beneficial effect associated with use of ultrasonic energy in comparison with monopolar electrosurgical energy in LC. Ultrasonic energy was found to lead to shorter operating times and less hospital stay, less blood loss, a lower incidence of gallbladder perforation, and less postoperative pain. However, the main disadvantages of ultrasonic dissection may be the instrument cost and learning curve of the surgeon, and for these very reasons, cost-benefit analyses and appropriate training programs may be necessary before implementing its use more generally.

Although this review provides the best available evidence for comparison of ultrasonic energy versus monopolar electrical energy in LC to date, as always there are some limitations in meta-analyses, particularly as a result of the nature of the primary data. To begin with, the studies were not blinded and adopted different surgical techniques; for example, two studies^16,20 used fundus-first dissection, whereas others reported different pneumoperitoneum pressures and used varying number of trocars for induction. All these factors could have led to a difference in outcome measures. Second, most of the analyzed studies had different follow-up periods, and some did not report any follow-up. Therefore, potential delayed biliary complications remain uninvestigated, which may lead to an imprecise estimation of any long-term beneficial effects. Third, a significant heterogeneity between studies was observed, including operative time and hospital stay. The reason for the observed heterogeneity in operative time may be variations in the experience of the operating surgeon and the patient's characteristics. Differences in the clinical approach at different institutions may have caused the heterogeneity in the duration of hospital stay. Although every means possible has been used to remove bias, notably by including a number of sensitivity analyses that made no difference to the results, some effect may remain.

Conclusions

In conclusion, this meta-analysis reveals a possible benefit associated with the use of ultrasonic energy over monopolar electrical energy in LC, entirely compatible with the better view afforded and decreased likelihood of lateral energy spread. Our data indicate that ultrasonic energy is as safe and effective as electrosurgical energy and potentially might be safer in LC. However, cost-effectiveness needs to be established in well-structured cost-benefit analysis before its use can be recommended for general application.

Footnotes

Disclosure Statement

No competing financial interests exist.

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