Single-Incision Laparoscopic Sleeve Gastrectomy: Review and a Critical Appraisal

Abstract

Background:

Single-incision laparoscopic surgery has attracted a great deal of interest in the surgical community in recent years, including bariatric surgery. Single-incision laparoscopic sleeve gastrectomy (SILSG) has been proposed as an alternative to the multiport laparoscopic procedure; however, it has yet to meet wide acceptance and application.

Objective:

We aim to summarize existing data on SILSG and check the procedure's feasibility, technical details, safety, and, if possible, outcomes.

Materials and Methods:

We checked the most important databases for studies concerning SILSG and included all these that summarized the criteria placed and contained the data needed for this review. We excluded case reports.

Results:

Nineteen studies complied with the criteria of our review, containing a total of 1679 patients. Their mean age has been 38.91 years and the mean preoperative body mass index has been 41.8 kg/m². In majority of cases (60.5%), a left upper quadrant incision has been preferred and in 97.6%, a commercially available multiport system has been picked. A wide variety of instruments have been used and mean operating time has been 94.6 minutes. One conversion to open surgery has been reported and 7.4% required the placement of additional ports. There was a complication rate of 7.38% (most common being bleeding with a rate of 2.5%) and a reoperation rate of 2.8%. Mean excess weight loss for a follow-up of 1 year was achieved in 53.7% of patients and was 70.06%. A tendency for less analgesia and better wound satisfaction has been reported.

Conclusions:

SILSG is safe and feasible. However, there is insufficient evidence to recommend it as the new gold standard for sleeve gastrectomy in the place of conventional laparoscopic sleeve gastrectomy. Randomized controlled trials are needed to analyze the results and the possible benefits of this technique.

Introduction

Morbid obesity has been recognized as a global epidemic in both developed and developing countries worldwide.¹ Over the last six decades, variable bariatric procedures have been developed to treat morbid obesity providing weight loss and correction of comorbidities resulting in a survival advantage.²

In the quest for less abdominal trauma, reduction of postoperative pain, as well as enhanced recovery, minimal access surgery has been gaining ground along with instrument innovations allowing even less incisions. Single-Incision Laparoscopic Surgery (SILS) and Natural Orifice Transluminal Endoscopic Surgery (NOTES) techniques are developed worldwide to provide major procedures with one or even no incision.

Laparoscopic sleeve gastrectomy has been originally introduced as the first-step restrictive part of a more complex malabsorptive bariatric procedure, the duodenal switch.³ Since then, it has evolved as the sole bariatric procedure due to the resulting considerable weight loss as well as the technical simplicity over the malabsorptive procedures, and the lack of a foreign body. The recent American Society for Metabolic and Bariatric Surgery position statement on the sleeve gastrectomy has also confirmed its use as the sole bariatric operation.⁴

Traditionally, laparoscopic sleeve gastrectomy requires five to six skin incisions to allow the placement of multiple trocars and removal of gastric specimen. The continuous development of SILS and its establishment in a variety of operations^5–10 have led to the development of single-incision laparoscopic sleeve gastrectomy (SILSG), and a growing number of case series has been reported so far.

SILSG brings together the cosmetic advantages of single incision and the familiarity of conventional laparoscopic surgery. It offers a more “anatomic friendly” abdomen incision and when necessary, the transition from SILSG to multiport surgery is as simple as introducing an extra trocar. However, the high-risk patient population and the unavoidable need for the development of highly customized instrumentation to achieve triangulation and avoid clashing of instruments are some of the major impediments to the wide implementation of this technique.

The purpose of the following article is to summarize the current situation and provide conclusions over the feasibility and safety of SILSG as well as arguments for it through a thorough review of the current reports on this procedure.

Materials and Methods

A thorough search of the literature was performed in Medline and Google Scholar on February 15, 2016. The search included the following keywords in all possible combinations: “single incision,” “single site,” “single port,” “less,” “single trocar,” “sleeve gastrectomy,” and “bariatric.”

Existing literature was searched to identify eligible articles that fulfill the following criteria:

1. The reported operation was SILSG in humans for morbid obesity.

2. Patient demographics as well as intraoperative and postoperative complications were clearly stated.

3. Case reports were excluded from the study.

The reference lists of these articles were also reviewed to find additional information.

Article selection

From the retrieved studies, 90 were extracted for eligibility and 19^11–29 were deemed appropriate for this analysis.

Data extraction

For each eligible study, data were extracted according to demographics (number of patients, mean age, sex, preoperative body mass index [BMI], and exclusion/inclusion criteria), operative technical details (site and length of incision, port used, instruments used, use of drains/nasogastric tube, and operative time), use of extra ports/incisions, methods of liver retraction, intraoperative and postoperative complications, and length of hospital stay. We also included % excess weight loss (EWL) as well as long-term complications (i.e., incisional hernia) whenever possible since not all of the studies had the same follow-up of their patients.

Statistical analysis

All data extracted were tabulated and the outcomes were analyzed cumulatively. A descriptive approach was attempted in all parameters. No further statistical analysis was performed.

Results

Patient demographics

The selected articles contained data on 1679 patients. Of them 1463 (87.1%) were female and 216 (12.85%) were male. Their mean age was 38.91 years and the mean preoperative BMI was 41.8 kg/m² (Table 1).

Table 1.

Patient Demographics

Author	Type of study	Cases (F/M)	Mean age (years)	Mean preoperative BMI (kg/m ² )
Gentileschi et al.¹¹	Prospective	8 (5/3)	44.4	56.2
Saber et al.¹²	Retrospective	14 (7/7)	44.2	51.6
Taller et al.¹³	Prospective	10 (10/0)	37.6	41.2
Maluenda et al.¹⁴	Prospective	20 (20/0)	34.5	35.1
Huang et al.¹⁵	Prospective	6 (6/0)	n/m	n/m
Saber et al.¹⁶	Prospective	7 (5/2)	46.1	49.3
Rogula et al.¹⁷	Prospective	14 (12/2)	48.1	40.2
Gomberawalla et al.¹⁸	Retrospective	36 (34/2)	43.3	43.06
Fernández et al.¹⁹	Retrospective	74 (72/2)	34.2	34
Lakdawala et al.²⁰	Prospective	300 (278/22)	35.5	39.9
Galvani et al.²¹	Prospective	7 (7/0)	34	49
Park et al.²²	Prospective	25 (23/2)	46.8	47
Pourcher et al.²³	Prospective	60 (54/6)	40.1	46.5
Noel et al.²⁴	Prospective	10 (10/0)	41.5	40.11
Mittermair et al.²⁵	Prospective	40 (40/0)	37	40.8
Delgado et al.²⁶	Prospective	20 (15/5)	46.8	40.1
Alevizos and Lirici²⁷	Prospective	12 (9/3)	44.5	41.8
Pourcher et al.²⁸	Prospective	16 (12/4)	17.8	45.3
Gaillard et al.²⁹	Retrospective	1000 (845/155)	40.1	42.6
Total		1679 (1463/216)	38.9	41.8

BMI, body mass index.

Exclusion and/or inclusion criteria varied a lot between the studies. All of them included patients who matched the NIH criteria for bariatric procedures. Of all the studies, only one²⁸ has been reporting operations performed solely on adolescents and had a unique protocol of inclusion criteria.

The studies showed a tendency to avoid superobese patients (BMI >50), patients with previous surgeries in the upper abdomen with scars on the abdominal wall, patients suffering from ventral hernias or having repaired ones with mesh, as well as patients tall or with an expected big left liver lobe (Table 2).

Table 2.

Exclusion/Inclusion Criteria

Author	Inclusion criteria	Exclusion criteria
Gentileschi et al.¹¹	n/m	Previous abdominal surgery
Saber et al.¹²	n/m	1. Previous bariatric surgery. 2. Previous upper abdominal surgery. 3. Previous ventral hernia repair
Taller et al.¹³	n/m	n/m
Maluenda et al.¹⁴	1. Obese conditions. 2. Medically indicated LSG. 3. BMI equal to or less than 40 kg/m². 4. Distance <22 cm between the xiphoid appendix and the umbilicus. 5. Interest in having surgery with less incision. 6. Female gender. 7. Written informed consent
Huang et al.¹⁵	n/m	n/m
Saber et al.¹⁶	1. Preoperative BMIs between 35 and 55 kg/m². 2. Peripheral obesity.
Rogula et al.¹⁷	1. BMI <50 kg/m². 2. Abdominal wall fat distribution. 3. Absence of prior surgical scars.
Gomberawalla et al.¹⁸	n/m	1. Previous upper GI surgery. 2. BMI >50
Fernández et al.¹⁹	1. BMI <50 kg/m². 2. Xiphoumbilical distance <25 cm. 3. The absence of large abdominal scars or other elements that compromise the cosmetic benefit of the procedure.
Lakdawala et al.²⁰		1. BMI >60. 2. Scarring of abdomen. 3. Ventral hernias. 4. Diaphragmatic hernias
Galvani et al.²¹	n/m	n/m
Park et al.²²		1. Open upper abdominal surgery. 2. Ventral hernia repair with mesh. 3. A liver size 20 cm
Pourcher et al.²³	n/m	n/m
Noel et al.²⁴	1. Female. 2. BMI between 35 and 45 kg/m². 3. No previous surgery	n/m
Mittermair et al.²⁵	n/m	1. Heavy sweat-eaters. 2. BMI greater than 45 kg/m². 3. Tall patients (height greater than 180 cm) 4. Patients with prior upper abdominal surgery or prior umbilical hernia repair with mesh. 5. Patients with hiatal hernia or functional disorders of the lower esophageal sphincter. 6. Patients with psychiatric disorders and addiction to either drugs or alcohol. 7. Patients with high operative risk.
Delgado et al.²⁶	n/m	n/m
Alevizos and Lirici²⁷	1. Age <60 years. 2. ASA score <III. 3. BMI <50.	n/m
Pourcher et al.²⁸	1. Nonsyndromic “idiopathic” obesity. 2. BMI >40 or >35 with severe comorbidities 3. Age older than 14 years. 4. Failure to achieve a weight loss >3% of baseline weight despite an intensive follow-up. 5. A strong and comprehensive motivation for surgery tested with repeated interviews and questionnaires.	Patients with major psychosocial instability
Gaillard et al.²⁹	French guidelines	n/m

BMI, body mass index; GI, gastrointestinal; LSG, laparoscopic sleeve gastrectomy.

Operative technical details

Arguably, these constituted the most variant part of the study since the surgical technique and the instrumentation is far from being standardized, and almost every study used a different surgical approach and instrumentation. In a majority of studies (15 out of 19), an umbilical incision was performed. However, in a majority of patients (60.5%), an upper left quadrant incision has been preferred, whereas an umbilical incision was performed in 38.5%, and the rest were paramedian or rarely epigastric. The length of the incision also varied between 1.8 and 4 cm. The incision of the left upper quadrum was transverse, while the umbilical incision could be vertical, transumbilical, or hemicircular. In 97.6% of the cases, a commercially available single-port device was used (22% SILS, 67.3% LESS, and 5.45% GELPOINT, rest being SPIDER, OCTO, and SSL) and in 2.4%, regular ports were placed through the same skin incision, but through different fascial incisions (Table 3).

Table 3.

Instrumentation, Elements of Surgical Technique

Author	Site of incision	Size of incision, cm	Port device	Laparoscope	Instruments	Integrity test	Drain
Gentileschi et al.¹¹	Umbilicus	2	SILS port (Covidien, Norwalk, CT)	5 mm, 30° rigid	Regular	Methylene blue 30–60 cc	0
Saber et al.¹²	Umbilicus or epigastric	2.5	SILS port (Covidien)	5 mm flexible tip	Flexible	Methylene blue 30–60 cc	0
Taller et al.¹³	Left pararectus	2	SILS port (Covidien)	10 mm, 30/45° rigid	Regular	Methylene blue 30–60 cc	0
Maluenda et al.¹⁴	Umbilicus	3	SSL port (Ethicon Endo-surgery, Cincinnati, OH)	5 mm, 30° rigid	Curved grip forceps	Methylene blue 30–60 cc	0
Huang et al.¹⁵	Umbilicus	6	Multiple conventional ports	10 mm, 30/45° rigid	Regular	n/m	0
Saber et al.¹⁶	Umbilicus	2.5	Multiple conventional ports	5 mm, flexible tip	Flexible grasper	Methylene blue 30–60 cc	1 through umbilical incision 19F blake
Rogula et al.¹⁷	Umbilicus	2.5–3	Multiple conventional ports	5 mm, 45° rigid	Regular	Methylene blue 30–60 cc	0
Gomberawalla et al.¹⁸	Umbilicus	n/m	LESS Triport/Quadport (Olympus Medical, Nagano)	5 mm flexible tip	Curved graspers	Endoscopy	0
Fernández et al.¹⁹	Umbilicus	2.5	Gelpoint (Applied Medical, Rancho Santa Margarita, CA)	5 mm, 45° rigid	Regular	Not performed	0
Lakdawala et al.²⁰	Umbilicus	2–2.5	SILS port (Covidien)	5 mm, 30° rigid	Regular	Methylene blue 30–60 cc	0
Galvani et al.²¹	Paramedian	4	SILS port (Covidien)	5 mm, 30° rigid	Regular	Methylene blue 30–60 cc	0
Park et al.²²	Umbilicus	2	SILS port (Covidien)	5 mm flexible tip	Curved graspers	Endoscopy	0
Pourcher et al.²³	Umbilicus	2.5	LESS Triport/Quadport (Olympus Medical)	5 mm, 30° rigid or 10 mm flexible tip	Double-curved graspers	Per os contrast CT scan	0
Noel et al.²⁴	Umbilicus	1.8	SPIDER (Transenterix Surgical, Durham)	5 mm, 30° rigid	Flexible graspers	Methylene blue 30–60 cc	n/m
Mittermair et al.²⁵	Umbilicus	3–4	OCTO Port (DaliSurgnet, Seoul)/Gelpoint (Applied Medical)	5 mm, 30° rigid	Flexible grasper	Not performed	0
Delgado et al.²⁶	Umbilicus	2.5	LESS Triport/Quadport (Olympus Medical)/SILS port (Covidien)	5 mm, 30° rigid	Regular	n/m	0
Alevizos and Lirici²⁷	Umbilicus	2–3.5	LESS Triport/Quadport (Olympus Medical)	5 mm, 30° rigid or 10 mm, 30°	Curved grasper	Not performed	1 Jackson-Prattt
Pourcher et al.²⁸	Upper left quadrant	2.5–3	LESS Triport/Quadport (Olympus Medical)	10 mm, 30° rigid or flexible tip	Double-curved graspers	No test mentioned—CT scan with contrast performed	0
Gaillard et al.²⁹	Upper left quadrant	2–4	LESS Quadport (Olympus Medical)/Octoport (Landanger, Chaumont)	10 mm flexible tip	Double-curved graspers	Not performed regularly, per os contrast on CT scan	Not placed regularly (no further details were mentioned)

CT, computed tomography; SILS, single incision laparoscopic surgery.

In 66.5% of the cases, a flexible tip laparoscope was used and for the rest of them, a rigid laparoscope was preferred varying in diameter (5 or 10 mm) and angle (30 or 45°). For the largest patients, extralong laparoscopes and instruments were preferred. Regular graspers were used for 26.4% of the procedures. The rest were curved, double curved, or flexible tip graspers.

A wide variety of thermofusion/dissecting instruments and stapling devices were used according to the preference of the surgeon and the ports used. The integrity of the staple line was inspected usually with methylene blue infusion and if any bleeding occurred, clips were used. Suturing of the staple line for reinforcement followed according to the preferences of the surgeon. No inability to reinforce the staple line due to the SILS approach was reported. The specimen was extracted through the incision used for the instruments. The mean operative time was 94.6 minutes (Table 4) with a tendency to drop significantly in larger series.^11,20

Table 4.

Operation Times, Hospitalization, Complications

Author	Cases	Mean operation time (min)	Mean hospitalization (days)	Complications
Gentileschi et al.¹¹	8	128	2.4	1 wound infection
Saber et al.¹²	14	121	1.4	0
Taller et al.¹³	10	n/m	2	2 wound seroma
Maluenda et al.¹⁴	20	127	n/m	0
Huang et al.¹⁵	6	65	n/m	1 wound seroma
Saber et al.¹⁶	7	143	2	0
Rogula et al.¹⁷	14	n/m	3	1 atrial fibrillation
Gomberawalla et al.¹⁸	36	116	1	0
Fernández et al.¹⁹	74	48	2.4	1 PV thrombosis
Lakdawala et al.²⁰	300	45	n/m	2 wound infection
				3 incisional hernia
				2 leak
Galvani et al.²¹	7	103.8	2	0
Park et al.²²	25	118.4	n/m	1 pulmonary embolism
Pourcher et al.²³	60	86	4	1 leak
				1 hand paresthesia
Noel et al.²⁴	10	61	3.1	0
Mittermair et al.²⁵	40	84.8	5	1 leak
				1 bleeding
				2 reflux
Delgado et al.²⁶	20	79.2	2.75	2 bleeding
Alevizos and Lirici²⁷	12	151.7	n/m	1 bleeding
Pourcher et al.²⁸	16	66	4	0
Gaillard et al.²⁹	1000	112	4	38 bleeding
				28 leak
				20 incisional hernia
				5 fever
				4 wound infection
				3 pulmonary embolism
				1 diabetic ketoacidosis
				1 pneumonia
				1 arthritis
Total		94.6	03/07/16	124 (7.38%)

PV, portal vein.

Conversions/use of extra trocars

One conversion to open surgery has been reported.²⁹ The reason was inability to control bleeding from a short gastric vessel. A total of 125 cases (7.4%) required the placement of one or more trocars (Table 5).

Table 5.

Placement of extra trocars

Author	No. of Cases that needed extra trocars	Reason for placement of extra trocars
Saber et al.¹²	1	Not mentioned
Maluenda et al.¹⁴	1	1 exposure due to bulky liver
Fernández et al.¹⁹	3	1 exposure due to bulky liver
		2 bleeding from short gastric vessel
Galvani et al.²¹	1	1 exposure due to bulky liver
Park et al.²²	1	1 inadvertent transection of the nasogastric tube with a linear cutting stapler
Pourcher et al.²³	13	13 exposure due to bulky liver
		3 conflict of instruments
Delgado et al.²⁶	20	15 exposure due to bulky liver
		2 endoGIA length
		1 umbilical hernia
		1 pneumoperitoneum loss
		1 separate fundus
Alevizos and Lirici²⁷	8	1 intraoperative bleeding
		7 exposure due to bulky liver
Gaillard et al.²⁹	78	19 adhesions in upper abdomen
		56 exposure due to bulky liver
		3 bleeding

Complications, deaths, and length of hospital stay

There were 124 intraoperative, postoperative, and during mid- and long-term follow-up complications reported, which make a complication rate of 7.38%. All in all, there was one death reported (0.06%). Gaillard et al.²⁹ report of a patient who suffered of recurrent venous thromboembolic disease, who despite the therapeutic administration of antithrombotic agents suffered from recurrent pulmonary embolism postoperatively, leading to acute heart failure and death on postoperative day 10.

The mean length of hospital stay was 3.7 days (range 1–12 days, Table 4).

Outcomes

Mean EWL ratio data were not available for all studies since the follow-up period between the operation and the publication of each study varied a lot. However, we were able to identify the % EWL for a follow-up of 6 months for 32% of the patients and it was 60.07%, and for 1-year follow-up for 53.7% of the patients, it was 70.06%.

What is more, there was a tendency for less analgesia use as well as better wound satisfaction between the patients who had undergone the SILS sleeve procedure.

Discussion

Over the last decades, morbid obesity has emerged as a global endemic with profound adverse metabolic consequences. Its complex pathways are still under investigation; however, when it comes down to definitive therapy, surgery is currently the only effective treatment, providing sufficient weight loss, amelioration of associated comorbidities, and actual increase of life expectancy of the affected patients.²

Nowadays, bariatric procedures are going hand in hand with laparoscopy to such a degree that whenever sleeve gastrectomy or gastric bypass is mentioned, the laparoscopic setup comes in mind. Ever since laparoscopic surgery has been regarded the new “standard of care” in bariatric and general abdominal procedures,^30,31 a new quest has emerged concerning the further reduction of already minimal invasion for the patients undergoing surgery, such as by using natural orifices or by minimizing the number of ports for access in the peritoneal cavity. Subsequently, SILS has received quite some interest and during the last decade, many studies have explored the feasibility and outcomes of various procedures performed in this way.^32,33 Moreover, newer technologies and instruments have risen, providing solutions to many of the problems that single-incision laparoscopy has encountered during its first steps.

The SILS technique was first described 20 years ago when Pelosi performed supracervical hysterectomies through a single umbilical incision.³⁴ In the late 1990s, the scope of SILS expanded to general surgery. Esposito³⁵ reported the use of a single-incision technique for appendectomy and Navarra et al.³⁶ reported the first cholecystectomy in 1997. The complex nature of bariatric procedures as well as the inherent anatomy and comorbidities of obese patients rendered SILS repelling for this population. However, the expansion of the SILS techniques and the introduction of new instrumentation made its implementation feasible even in this surgery domain, and in 2008, Nguyen et al.¹⁰ described the first cases of gastric banding and Saber et al.¹² published the first experiences with single-incision sleeve gastrectomy. Finally, in 2009, Saber et al.³⁷ and Huang et al.³⁸ reported the first single-access Roux-en-Y gastric bypass.

In our analysis of the accumulated data on SILS sleeve gastrectomy specifically, concerning already several hundreds of patients, a tendency toward young female patients (87.1% of the patients, 38.9 years mean age) has been observed. This can be explained by the fact that women represent a more SILSG-friendly patient population: they are usually shorter, their liver is smaller, and they have more adipose tissue in the thighs and the gluteal area, and less visceral fat, so they tend to be less challenging. Moreover, the main advantages of SILSG namely the better cosmesis and enhanced recovery it can provide, are characteristics a young female patient would take into account when asked to participate in a survey for a new procedure.

Reading through the inclusion (or exclusion) criteria, we could summarize them as follows in: (1) BMI <50, (2) height <180 cm, (3) no previous upper abdominal surgery, (4) no abdominal scarring, (5) no ventral hernias, and (6) no hiatal hernias (Table 2).

These aforementioned criteria are stricter than the ones used for conventional laparoscopy SG; however, there is no exclusion based on the actual comorbidities of the bariatric population, rather aspects that are expected to make SILSG technically demanding. What is more, most of the initial studies clearly stated inclusion of “selected patients.” This course of action is only natural in the evolution of a new surgical technique. The growing experience on the procedure and the rising new instrumentation following the feedback of these pioneering surgeons have given some authors the ability to avoid such strict inclusions and operate on superobese or the more technically demanding patients, and even combine it with another operation (i.e., cholocystectomy). Furthermore, Gaillard et al., which report the largest series so far with 1000 patients, have been routinely performing SILSG providing it without restriction criteria.

The initial inclusion of low BMI patients and exclusion of superobese patients have various explanations. A higher BMI usually comes with a larger fatty liver that represents one of the biggest challenges in SILSG. Moreover, superobese patients' umbilicus creates a torque effect, thus making the positioning of instruments more difficult plus increasing the distance between the incision and the xiphoid. A long distance between the umbilicus and gastroesophageal junction is the reason behind early exclusion of tall patients as well, since it makes access to the fundus more difficult, resulting in a demanding and sometimes impossible adequate stomach excision. However, longer instruments, curved or flexible, have given the surgeon the ability to reach these distances and maneuver in the abdomen in a way that made SILSG feasible for these patients as well.

Previous surgeries were part of the exclusion criteria since they resulted in more intra-abdominal adhesions and made the operation even more challenging. Scarring of the abdominal wall also negated by definition any cosmetic advantage, so many of the authors found that proceeding in an SILSG had less to offer.

As stated multiple times before, instrumentation plays a key role in SILSG and has met a great evolution during the last years. In the first published reports, SILSG had been performed with regular trocars through one incision, but in the later reports, the trend has been toward multiport trocars: they can be used through a 2.5–3 cm skin and fascia incision and can offer up to four ports, while avoiding the crowding resulted by the placement of three regular trocars in such a small area. Moreover, multiport devices can offer ease in trocar interchange without air leakage during the operation, and the surgeon can change the variable instruments between trocars for better access and triangulation without having to lose intra-abdominal pressure and time. In addition, the fascial incision needed is comparable in size to the incision performed for stomach extraction in conventional laparoscopy.

Although SILSG can be performed with conventional 10-mm front-view laparoscopes and straight instruments, crowding over the working area decreases the freedom of motion for the surgeon and assistant. Furthermore, limited triangulation increases the difficulty of tissue exposure and dissection. The use of 5-mm laparoscopes with angled view or flexible tip scopes as well as curved and flexible instruments improves exposure and manipulation, a tendency that can be seen in the majority of studies selected for this review.^{12,14,16,18,22–26,28,29}

Nevertheless, going past the problems of crowding and clashing of instruments, triangulation problems, visualization, and exposure issues, one of the greatest challenges in SILSG remains inadequately solved: liver retraction has been one of the biggest obstacles SILSG has encountered since the first case reports. Every author has particularly stated this fact and it has been a matter of great importance in every study so far. The inclusion criteria made for every study tried to incorporate patients with small livers (thus the smaller BMI and the younger patients usually selected).

What is more, various techniques have been used to retract the liver: Gentileschi et al.¹¹ used the laparoscope to retract the liver in their patients. Saber et al. initially used a suture covered by an 18F part of a rubber catheter placed in the abdomen and fixated on the diaphragm and through the abdominal wall to retract the liver, while avoiding lacerating it,¹² and in another study, Rogula et al. preferred to use a 5-mm Nathanson retractor through an epigastric incision without using a port whenever needed.¹⁷ Taller et al.¹³ used the gastric remnant to retract the liver and whenever that was not possible, they used a liver retractor placed through an extra port or even through the air insufflation port provided by the multiport they used. Maluenda et al.¹⁴ preferred to use a Veress needle to retract the liver if needed, while Huang et al.¹⁵ proposed a tape-covered suture (tape consisting of a part of a Jackson-Pratt drain) that lifted the liver and was fixated on the abdominal wall. They even calculated the time needed for this part of the procedure. Gomberawalla et al.¹⁸ proposed the use of a 2.5 mm epigastric skin incision to introduce a liver retractor, whereas Galvani et al.²¹ proposed a custom-made intra-abdominal retractor composed by a bulldog and a hook.

Finally, a number of authors have also proposed using the curved part of graspers to retract the liver, while lifting the stomach,^22–25,29 although that met criticism since a maneuver like this could compromise the adequate resection of the gastric fundus, thus affecting negatively the longterm outcomes. However, Gaillard et al. who use the curved part of the instruments have found, in their study, that this method does not compromise the outcomes of the surgery during the first 2 years of follow-up they have available for their patients.²⁹ All in all, it is evident that liver retraction in SILSG is pivotal and all the authors spent energy and thought over how to overcome it providing a wide variety of solutions, although none of them has met the general acceptance. Thus, we believe that a consensus has to be made toward the solution of this problem that hinders the standardization of SILSG technique and even leads to abandoning its principles by introducing extra trocars.

The mean time of SILSG has been 94.6 minutes in our sample. In the studies included in this review, the time of operation is comparable to that of standard LSG and many authors commented that, toward the last patients of their reports, the time needed for SILSG had been gradually less.

The SILSG working environment did not refrain surgeons from liberally using their method of choice regarding integrity of staple line testing, staple line reinforcement, placement of drains, and so on.

SILSG, in this study, showed a complication rate of 7.38% (taking incisional hernias into account). This rate meets the rates of morbidity in laparoscopic sleeve gastrectomy in high-volume centers.³⁹ Delgado et al.²⁶ report of two complications that required reoperation due to early intra-abdominal bleeding without giving out more details. Mittermair et al.²⁵ report of 2 cases: 1 staple line leak that required relaparotomy for oversewing and 1 case of hemoperitoneum that required SILS relaparoscopy and clip placement. Gaillard et al.²⁹ report of 24 relaparoscopies due to bleeding (12 from the staple line, 1 from greater omentum, and 1 from liver decapsulation, no active bleeding was discovered in the rest) and 19 relaparoscopies combined with endoscopy due to leakage from the staple line (evacuation and drainage of abscess and endoscopic assessment and dealing). However, reoperations should always be considered with great caution when evaluating a surgical innovation, especially when the surgeons performing the operations are as mentioned before experts.

Morbidity associated with the abdominal trauma and incision has also been of great interest. The hypothesis has been that the use of a single incision should be correlated with a lower number of complications. Less incisions equal less candidates for infection sites; the abdominal wall incision is more “anatomic friendly,” has lower chances of bleeding, and offers a better material for an effective closure and a safer way to enter the peritoneal cavity. In contrast, many of the authors argue that the larger incision size, the severe parietal contusion, and the longer duration of the surgical procedure can be associated with an increase in wound infection and incisional hernia rates.^40,41

In our review, we observed 10 wound complications (0.6%, Table 4). Moreover, only 23 incisional hernias were registered, although the follow-up period in the majority of these studies was not adequate enough to evaluate safely the relative risk. Three hernias were reported from Lakdawala et al. who preferred a transumbilical approach. The author of the study does not hesitate to state in his conclusions that “the myth of high long-term incisional hernia rate after single-incision surgery has been dispelled.”²⁰ The remaining 20 were reported by Gaillard et al.²⁹ We have to add here that, in the aforementioned study, the authors preferred an upper left quadrant incision, and performed SILSG in a routine manner without strict inclusion criteria and an abdomen computed tomography (CT) scan as an imaging modality when assessing their patients at 1 year of follow-up (546 patients available for CT scan in 1 year of follow-up, making it a 3.7% incidence in this study, or 2% if we prefer to refer to the original pool of patients). Maybe these contributed in their higher incidence of incisional hernia reported.

We can safely presume that, while the arguments supporting the safety and advantages of SILSG concerning the abdominal incision and trauma will remain intact for the years to come, at the same time, the reservations against are deemed to lose ground since the incision required for the placement of multiports is growing smaller and the mean operation time seems to drop after a certain amount of cases.

Postoperative pain has been less studied in the reports used especially in the first postoperative day.^17,20 The cosmetic result can be an important outcome to consider in the bariatric population since it consists of socially active young patients and the goal of therapy is to provide survival and quality of life equal to the one of the general population. In the study published by Yeung et al.,⁴² a visual analog scale was used to evaluate cosmetic outcome after laparoscopic hysterectomy and it concluded that patients preferred an umbilical single incision for the procedure. Two studies evaluated the cosmetic result, which was better rated among patients who underwent single-incision bariatric surgery,^43,44 although these studies evaluated cosmetic result shortly after surgery (1 and 3 months).

Last, but not least, in the era of cost-effectiveness, attention has been drawn in the cost of SILSG. An estimation of it and a head-to-head comparison with other treatment options is of outmost importance when trying to evaluate a new technique, especially in an era of vast financial problems that apply pressure to national healthcare systems worldwide. The studies reviewed failed to provide consistent data regarding it. The vast majority of them were studies referring mainly to the safety and feasibility of the SILSG, thus cost was not taken into account.

From studies regarding bariatric surgery, there is a trend for the costs to be comparable since the multiport channels used compensate for the multiple trocars used otherwise. Moreover, we should take into consideration that if SILSG was widely applied and its instrumentation massively produced, most probably, costs could be lowered. The length of the operation that could pose a problem, as well, seems to be a matter of a learning curve as in the larger series, there has been a trend toward shorter operation times, ones comparable with conventional LSG. Enhanced recovery after SILSG is another factor that contributes toward lessening the expenses of the procedure even further.

It has been clear that the length of stay after SILSG is actually shorter compared to that after conventional laparoscopic SG. Furthermore, the enhanced recovery and the minimized postoperative analgesia needed can also imply the need of more flexible facilities for the needs of postoperative hospitalization of patients undergoing SILSG. Although data are poor until now, there is a strong implication that SILSG can prove equal, if not cheaper, to conventional LSG in terms of cost, while combining enhanced patient recovery and satisfaction.

Of course this review has certain limitations. It fails in providing circumstantial answers in the form of a strong statistical analysis. The fact that the majority of the studies included initial experience and data from selected patients makes it difficult (and most probably inappropriate) to extrapolate these results. No randomized controlled trial was involved. Most of the studies were observational and heterogeneous and as already said, no meta-analysis can be performed. Other limitations include the heterogeneity among the different studies in terms of different access devices, instruments, and equipment used. What is more, the majority of the cases reported come from two studies namely Lakdawala et al.²⁰ and Gaillard et al.,²⁹ resulting in a massive and probably misleading effect in result extraction. Finally, most studies have a follow-up of 1 to 6 months, a short period to study the incidence of incisional hernia and evaluate the % EWL. However, this review, in accordance to several studies,⁴⁵ provides support to the wider acceptance of SILSG as a potential treatment option for morbid obesity.

Conclusions

SILSG is a safe and feasible operation when performed in a controlled environment. However, there is a great need for standardization of the technique and a widely accepted method of liver retraction that seems to pose the greatest obstacle during the operation. The data so far point toward a trend of less operative pain and hospital stay, but they failed to accompany this trend with a statistical significance, while the available evidence suggests that the primary benefit of this approach could be the cosmetic result, which is something not to be taken lightly. The bariatric community has to decide if SILSG is an alternative for selected patients or if it opts to become the new “standard of care” for patients undergoing sleeve gastrectomy. Randomized control trials are needed after an initial period of implementation of standardized techniques and the associated learning curve, to analyze the long-term results in terms of weight loss, resolution of comorbidities, estimation of long-term complications, and ultimately its cost-effectiveness.

Footnotes

Disclosure Statement

No competing financial interests exist.

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