Safety and Efficiency of Single-Incision Laparoscopic Cholecystectomy in Obese Patients: A Case-Matched Comparative Analysis

Abstract

Background:

Single-incision laparoscopic surgery (SILS) is feasible and safe for most situations that indicate a need for cholecystectomy in normal-weight patients. SILS might offer several potential benefits over multiport laparoscopy. However, the effect of obesity on the surgical outcomes of single-incision laparoscopic cholecystectomy (SILC) has not been sufficiently investigated and is controversial. The aim of this study was to compare normal-weight and obese patients who had undergone SILC.

Methods:

All single-incision laparoscopic cholecystectomies performed between December 2008 and December 2014 were reviewed and grouped according to patient's body mass index (BMI). Obese patients with a BMI ≥30 kg/m² who had undergone SILC were matched in a 1:2 ratio with non-obese patients.

Results:

One hundred six obese patients after SILC were compared with 212 non-obese patients according to age, gender, and indication for operation. Operation in obese patients was longer but without significant difference (53.9 minutes versus 62.3 minutes; P = .189). In each group, 4 patients needed conversion to multiport laparoscopy or open procedure (1.9% versus 3.8% for non-obese versus obese; P = .236). No significant difference was noted for postoperative complications (4.3% versus 5.7% for non-obese versus obese; P = .790) and the length of hospital stay (3.3 days versus 3.3 days; P = .958). Obese patients have a significantly (P = .027) higher incisional hernia rate (9.8%) than non-obese patients (1.9%), with obesity being a risk factor for hernia development in the univariate analysis.

Conclusion:

SILC in obese patients is technically feasible and safe compared with non-obese patients in regard to postoperative complications, conversion rates, and length of hospital stay but with an almost sixfold risk of umbilical incisional hernia on the long run.

Introduction

The worldwide prevalence of obesity has increased dramatically within the last few years. In 2014, ∼600 million (∼13% of the world's population aged ≥18) adults were found obese with a body mass index (BMI) of >30 kg/m².¹ Obesity, however, is a risk factor for developing certain types of malignant cancer and several chronic diseases such as hypertension, diabetes, or coronary heart disease. Also benign gallbladder diseases seem to be associated with obesity.^2,3

For the treatment of the benign gallbladder pathology, multiport laparoscopic cholecystectomy (MLC) has become the gold standard since its introduction by Mühe in 1985.⁴ By now, several studies have demonstrated the safety of MLC in obese patients.^5–7 Overweight patients requiring a cholecystectomy can therefore profit from the advantages of laparoscopic surgery. However, within the last few years of ongoing development in minimal invasive surgery, single-incision laparoscopic surgery (SILS) has emerged as an alternative to conventional MLC. Due to the reduced incisional trauma of a single umbilical access, SILS has potential advantages, including cosmetic results, a lower postoperative pain score, and greater overall patient satisfaction.^8–11 Especially in the early years of SILS, questions regarding the feasibility in all patients were raised. High BMI, gender, and age were mentioned as possible parameters affecting the postoperative outcomes.⁸ In the current literature, the effect of obesity on the operative and postoperative outcomes after single-incision laparoscopic cholecystectomy (SILC) has not been sufficiently investigated, because in most series the number of patients included is small and mostly highly selected.

In this study, we report our experience of SILC in obese patients.

A retrospective review of demographic, operative, and postoperative data after SILC in a matched-pair analysis of obese patients and patients with normal BMIs was performed to evaluate the operative and postoperative outcomes.

Patients and Methods

Data of all patients undergoing an elective or acute SILC between August 2008 and December 2014 were collected in a prospectively maintained database. All patients with clinical and sonographic signs of symptomatic cholecystolithiasis were included in this study. Patients with the diagnosis of an acute cholecystitis or other pathologies requiring a cholecystectomy were also included. Patients were fully informed preoperatively about single-incision and multiport laparoscopic treatment options as well as the differences of both techniques. We started single-incision surgery in August 2008 with selected young, healthy patients of normal weight and extended the indication to all patients rapidly as our level of experience grew. We therefore excluded the first 100 performed SILCs in the database from this analysis to reduce the influence of the learning curve and the bias of highly selected patients in the early period. Patients were excluded from the analysis if the cholecystectomy was performed as part of another operative procedure.

Demographic variables, operative parameters, and postoperative outcome data were obtained and evaluated from a database with additional medical record review. Data fields analyzed included gender, age, BMI, score according to the American Society of Anesthesiologists (ASA), previous abdominal surgery, diagnosis, secondary diagnosis, operative time, intraoperative conversion, additional intraoperative procedures, intraoperative opening of the gallbladder, inserted drainage, intraoperative complication, postoperative complication, reoperation and length of hospital stay. The time of the surgical procedure was defined from the skin incision to the application of the last wound dressing. The length of hospital stay was defined as the time from admission or operation, counted as day 0, to discharge.

Patients were stratified into obese and non-obese cohorts by their BMI. According to the obesity fact sheet of the World Health Organization (WHO), obesity was defined as a BMI ≥30 kg/m².

Follow-up

A long-term follow-up was obtained by telephone and mail interviews according to the patients reported outcome algorithm reported by Baucom et al.¹² A clinical examination was offered to all patients, especially those with incongruent results regarding the interview. Patients were classified as lost to follow-up when no contact information was available or no contact was achieved after three trials by phone and by a mail questionnaire.

Surgical procedure

Antibiotic single-shot treatment consisting of cefotaxim or cefuroxim and metronidazole applied intravenously preoperatively in all patients. Antibiotic treatment was continued postoperatively according to the surgeon's instructions and the macroscopic findings.

Both surgeons were on the patient's left side with the patient in supine position. The monitor was positioned close to the patient's right shoulder. A 15–20 mm skin incision was performed directly through the middle of the umbilicus, and the fascia was also cut by this length in the linea alba. The port-system (TriPort™ or Triport+™; Olympus, Germany) was inserted using the supplied introducer. Diagnostic laparoscopy was performed using a straight 30° laparoscope. The patient was positioned in 10°–20° reverse Trendelenburg position and slightly tilted to the left. Two standard straight instruments (a grasper and a hook electrocautery device) were used. The gallbladder was held, and the hilum was prepared to expose the cystic duct and cystic artery. Both structures were clipped with an endoscopic clip applier (Ligamax™5; Ethicon) and cut in between. The gallbladder was then dissected from the fossa, and removed through the port-system without the use of an endobag. The fascia was closed in all patients with a nonabsorbable 0 suture and an absorbable 4/0 suture for the skin closure.

Matching procedure and statistical analysis

For every obese patient undergoing a SILC, 2 non-obese persons were identified from the database and were matched by gender and diagnosis, age was matched in a range of ±5 years. A randomizing function was used in cases of multiple possible matches.

All analyses were performed using SPSS, version 22 (IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0, Armonk, NY: IBM Corp). Variables are described as numbers with percentages, or as means ± standard deviation. Categorical variables were analyzed using the chi-square test (χ²) and numeric values by the Student's t-test. A univariate logistic regression, including demographic and operative parameters, was performed to identify possible risk factors for postoperative morbidity after SILC. A P value of <5% was regarded as statistically significant.

Results

One hundred six obese patients who had undergone SILC were matched in a 1:2 ratio and compared with non-obese patients after SILC (n = 212) (Table 1). Groups were matched in terms of gender, age, and diagnosis. In both groups, 25.5% of the patients were male (P = 1.000); the average age was 42.0 ± 13.7 versus 41.8 ± 13.9 (P = .890), respectively. The main diagnosis in all patients requiring a SILC was symptomatic cholecystolithiasis in 88.7%, followed by acute cholecystitis in 7.5%, biliary pancreatitis in 2.8%, and gallbladder polyp in 0.9% (Table 1). The groups of obese and non-obese patients did not differ significantly in terms of ASA scores and previous abdominal surgery. Secondary diagnoses were slightly more frequent in obese patients (34.0% versus 42.5%, respectively) but without reaching significance (P = .174). Looking at secondary diagnoses in more detail, hypertension and diabetes were seen more often in obese patients with 10.0% versus 18.0% (P = .128), respectively, and 1.4% versus 11.3% (P = .001), respectively.

Table 1.

Demographic Parameters

	Non-obese (n = 212)	Obese (n = 106)	p
Gender^a
Male	54 (25.5)	27 (25.5)	1.000^a
Female	158 (74.5)	79 (74.5)	1.000^a
Age^a (years)	42.0 ± 13.7	41.8 ± 13.9	.890^a
BMI (kg/m²)	25.0 ± 2.8	34.4 ± 4.0	<.001
ASA
I	77 (36.5)	31 (29.2)	.127
II	120 (56.9)	61 (57.5)
III	13 (6.2)	14 (13.2)
IV	1 (0.5)	—
Previous abdominal surgery	27 (13.2)	14 (13.2)	.573
Diagnosis^a
Symptomatic cholecystolithiasis	188 (88.7)	94 (88.7)	1.000^a
Acute cholecystitis	16 (7.5)	8 (7.5)
Biliary pancreatitis	6 (2.8)	3 (2.8)
Gallbladder polyp	2 (0.9)	1 (0.9)
Secondary diagnosis	71 (34.0)	45 (42.5)	.174
Diabetes	3 (1.4)	12 (11.3)	.001
Hypertension	21 (10.0)	19 (18.0)	.128
COPD	4 (1.9)	2 (1.9)	.810
Other	55 (26.0)	23 (21.7)	.287

Values as n (%) or in means ± standard deviation.

Matched parameters.

ASA, American Society of Anesthesiologists; BMI, body mass index; COPD, chronic obstructive pulmonary disease.

Perioperative outcomes are shown in Table 2. Mean operative times were 53.9 ± 21.3 minutes for non-obese and 62.3 ± 17.7 minutes for obese patients as shown in Table 2; this difference was not significant (P = .189). Intraoperative conversion rates were similar between the two groups (P = .236). In the non-obese group, 2 patients each (0.9%) had to be converted to multiport laparoscopy and open procedure. In the obese group, 4 patients (3.8%) required conversion to multiport (three or four ports) laparoscopy. Reasons for conversion were mainly difficult exposure and visualization. There were no differences regarding additional intraoperative procedures in both groups (P = 1.000). Additional intraoperative procedures included adhesiolysis, liver biopsy, or closure of ventral hernia. Intraoperative opening of the gallbladder was seen in both groups in 6 patients each (2.9% non-obese, 5.7% obese, P = .351). There was no significant difference in the number of insertions of intra-abdominal drainage between non-obese and obese patients (P = 1.000).

Table 2.

Operative Parameters

	Non-obese (n = 212)	Obese (n = 106)	p
Operative time (minutes)	53.9 ± 21.3	62.3 ± 17.7	.189
Conversion	4 (1.9)	4 (3.8)	.236
Multiport	2 (0.9)	4 (3.8)
Open	2 (0.9)	0
Additional intraoperative procedures	23 (11.2)	12 (11.3)	1.000
Gallbladder open	6 (2.9)	6 (5.7)	.351
Drainage	15 (7.4)	8 (7.5)	1.000
Intraoperative complication	0	0
Postoperative complication	10 (4.3)	6 (5.7)	.790
Wound infection	3 (1.5)	2 (1.9)
Bile duct complication	1 (0.5)	1 (0.9)
gallbladder fossa hematoma/seroma	3 (1.5)	2 (1.9)
Other	3 (0.9)	1 (0.9)
Length of hospital stay	3.3 ± 1.9	3.3 ± 1.5	.958

Values as n (%) or in means ± standard deviation.

The postoperative complications were not significantly different between the two groups (P = .790). Wound infections, rates of bile duct injury, and hematoma or seroma in the gallbladder fossa were comparable between the two groups. In both cases with the intraoperative bile duct injury, a laparoscopic repair was possible by suturing, followed by an endoscopic stent implantation intraoperatively in one case and the insertion of a T-tube drainage in the other case. As shown in Table 3, age, secondary diagnosis, previous abdominal surgery, obesity, or operative time are not significantly associated with postoperative morbidity after SILC.

Table 3.

Risk Factors for Postoperative Complications After Single-Incision Laparoscopic Cholecystectomy (n = 16)

	OR	95% CI	p
Age (years)	1.03	0.99–1.07	.208
Secondary diagnosis (no versus yes)	0.99	0.32–3.09	.991
Previous abdominal surgery (no versus yes)	0.88	0.19–4.04	.866
Obesity (no versus yes)	0.78	0.99–1.07	.654
Operative time (minutes)	0.99	0.97–1.02	.571

CI, confidence interval; OR, odds ratio.

The mean length of hospital stay for all 318 patients was 3.3 ± 1.7 days with a range of 2–18 days. This did not differ significantly between non-obese and obese (3.3 ± 1.9 non-obese, 3.3 ± 1.5 obese, P = .958).

About 53.1% of all patients (n = 169) were available for a long-term follow-up at mean 62.5 months after cholecystectomy. Eight patients (7.1%) were found to have an umbilical incisional hernia with a significant difference between non-obese and obese patients as shown in Table 4 (n = 2 [1.9%] versus n = 6 [9.8%]; P = .027). In the univariate analysis, obesity was a significant risk factor for an incisional hernia after SILC (Table 5).

Table 4.

Long-Term Follow-Up

	Non-obese (n = 212)	Obese (n = 106)	p
Complete follow-up	108 (50.9)	61 (57.5)	.285
Follow-up time	59.6 ± 24.6	68.0 ± 21.1	.226
Incisional hernia	2 (1.9)	6 (9.8)	.027
Incisional hernia repair	2 (1.9)	4 (6.6)	.190

Values as n (%) or in means ± standard deviation.

Table 5.

Risk Factors for Incisional Hernia After Single-Incision Laparoscopic Cholecystectomy (n = 8)

	OR	95% CI	p
Age (years)	0.95	0.89–1.02	.131
Gender (female versus male)	4.59	0.93–22.73	.062
Secondary diagnosis (no versus yes)	0.34	0.07–1.70	.188
Obesity (no versus yes)	5.84	1.04–32.70	.045
Operative time (minutes)	0.98	0.94–1.02	.346

CI, confidence interval; OR, odds ratio.

Discussion

The prevalence of obesity is dramatically increasing worldwide.¹³ Surgeons are therefore increasingly likely to treat a growing number of obese patients. In laparoscopic surgery, obesity goes along with additional technical difficulties, increased operative risks, and postoperative morbidity compared with non-obese patients. Not long ago, obesity was considered a relative contraindication to laparoscopy.¹⁴ However, with increasing experience and technical development the usage of laparoscopy in obese patients is growing within the last few years, and has been found to be safe and feasible.^7,15–17 The single-incision laparoscopic approach has recently emerged as a less invasive alternative to multiport laparoscopy, and has been promising in terms of technical feasibility, safety, and cosmetic outcome. Especially during the early period of this minimal invasive procedure, some authors believed that overweight individuals were unsuitable for SILS.^18,19

The aim of this study was therefore to review outcome parameters and verify the technical feasibility and safety of SILC in obese patients. We therefore performed a case-matched comparative analysis of obese and non-obese patients who had undergone SILC. A total of 318 patients were included and matched in a 1:2 ratio for obese versus non-obese by gender, age, and diagnosis. Case matching was performed to reduce the selection bias in respect to demographic parameters.

An important point, in our opinion, is that SILC in obese patients was not associated with an increased postoperative morbidity in this study. In a large meta-analysis including patients of every BMI, the local wound infection rate was 1.1% after MLC. Especially in obese patients, wound complications could be an essential problem mainly attributed to the extensive abdominal wall compared with non-obese. Yilmaz et al. found a rate of wound infection of 13.3% in their group of obese patients compared with 7.6% in the group of normal-weight controls. Other authors also report umbilical wound complications in obese patients of ∼10% in patients undergoing SILC or sigmoid colectomy.^20,21 We experienced wound complications in 1.5% (3 cases) in the normal-weight group versus 1.9% (2 cases) in obese patients, respectively. Serious complications such as bile duct injuries occurred in 1 case for each group (0.5% versus 0.9%). In conventional MLC, the rate of bile duct injury is ∼0.5%.^22,23 It is still discussed controversially whether the rate is higher in SILC.^24–27 A recently published meta-analysis including randomized trials found overall more adverse events after SILC but no significant difference in regard to bile duct injuries, which was confirmed by another meta-analysis.^25,26 In conclusion, the case number in this study and probably the overall case number of SILS procedures are still very small to detect significant differences in rare complications.

Earlier published studies with a special focus on obese patients undergoing SILC basically all found the duration of surgery to be prolonged in obese patients.^16,28–30 This is in agreement with our results. The mean operative time in this study was ∼10 minutes longer in obese patients undergoing SILC but without reaching statistical significance. Longer operative times in obese patients have been reported in multiport laparoscopy as well as in open cholecystectomy.^7,17 Although the operative time does not represent a true complication, it reflects technical difficulty. Intraoperative problems with the exposure of Calot's triangle in obese patients are mainly caused by additional fatty tissue, a fatty and mostly enlarged liver, and quite often problems with the pneumoperitoneum due to increased intra-abdominal pressure. The access to the abdominal cavity is also prolonged because the distance between the skin and the fascia is simply longer than that observed in non-obese patients. This also makes the closure of the fascia at the end of the operation more difficult, and long retractors can only slightly increase the sight on the fascia within the deep subcutaneous incision. On one hand, this might be an advantage of SILS because with the umbilical skin incision being minimally longer than that in conventional laparoscopy this might increase the sight on the fascia and therefore make the closure more safely. In addition in SILS, there is only one wound to close. On the other hand, the closure of the fascia is often found to be the crucial aspect of SILS because the risk of hernias might increase with the fascial incision being slightly longer than that observed for a 10–12 mm trocar as necessary for conventional laparoscopy. Long-term data regarding the incidence for incisional hernias after SILS are still rare, especially for obese patients. In this study, long-term follow-up data are available for around half of the included patients on average >5 years after cholecystectomy. The umbilical hernia rate was significantly around five times higher in obese than in non-obese patients. As it has been shown earlier, obesity increases the risk of umbilical incisional hernia after SILS.^31–34

In the current literature, only a few studies have evaluated the influence of obesity on conversion rates to multiport laparoscopy by adding trocars or to open cholecystectomy with controversial results. Khambaty et al. reported a conversion rate to multiport laparoscopy of 24% in a series of 107 single-incision cholecystectomies and found the converted cases to be significantly more obese than the cases that were treated successfully through a single incision.³⁵ In a more recent study, the BMI, height, and weight of the patients were found to have a significant impact on the conversion rate, with height being an independent risk factor for the need to insert an additional trocar in SILC.²⁹ Reasons for conversion were mainly inadequate exposure of Calot's triangle or acute inflammation.^29,35,36 Other studies go along with our findings, showing that the BMI has no significant effect on the need for conversion.^36,37

The authors acknowledge several limitations appertaining to all retrospective studies as it is the case in this study. However, the obese and non-obese patients were exactly matched by gender, age, and diagnosis to control for the effects of these parameters in advance of all other outcomes. Another limitation of our study is the relatively small number of patients with morbid obesity. Even though, to the best of our knowledge, this is the largest review of obese patients undergoing SILC to date, only 33 patients had a BMI >35 kg/m² with 12 patients >40 kg/m², thus meeting the WHO criteria for obesity classes II and III. Our findings regarding these patients should therefore be reviewed with caution and need validation by a larger sample size. In contrast to other reported studies, we can probably completely exclude a selection bias for patient characteristics, surgical indication, or a surgical expert bias. Indications such as acute cholecystitis and biliary pancreatitis were not excluded, and ∼13% of all included patients in both groups had previous abdominal surgery. As we were able to show in an earlier study, SILS can very safely be performed as a teaching operation for residents.³⁸ We therefore did not exclude those operations from the present analysis, which should reflect the reality of routine clinical practice.

Conclusion

Our case-matched comparative analysis of SILC in non-obese and obese patients reveals that the technique is safe and feasible in overweight patients. SILC in obese patients had longer operative times than the matched normal-weight cohorts but comparable intraoperative conversion rates, postoperative morbidity, and length of hospital stay. Regarding the long-term follow-up, obese patients have a significant higher risk of developing an umbilical incisional hernia.

Footnotes

Disclosure Statement

No competing financial interests exist.

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