over the past two decades , the progress on the laparoscopic techniques has imposed laparo - endoscopic surgery as a valuable alternative to the traditional open surgery . minimally invasive techniques have demonstrated to be efficient in causing a reduced surgical trauma , thus decreasing the probability of post - operative complications and the length of hospital stay . improvement at post - operative pain and at the aesthetic result cosmesis are well established additional advantages of the laparoscopic management . the origin of laparoscopy goes back to over a century ago when george kelling in order to visualise the viscera of a living dog , introduced a cystoscope into the peritoneal cavity while insufflating air so as to improve the view . in 1992 , the first laparoscopic liver resection was performed . nevertheless , the proliferation of major hepatectomies performed by the laparoscopic approach has been much slower because of the complexity of the procedure , the increased probability of uncontrolled haemorrhage , the technical difficulties of such operation and the essential learning curve . the development of minimally invasive surgery as well as the progress on medical technology permitted the realisation of major laparoscopic hepatectomies with satisfying outcomes . recently , innovations in the field of single incision laparoscopic surgery ( sils ) allowed the achievement of single incision laparoscopic hepatectomy ( silh ) expanding the frontiers of minimally invasive surgery . the aim of this article is to present the available till now clinical evidence regarding the utilisation of silh as a method of treatment in both benign and malignant hepatic pathologies , on the base of the existing literature . we performed a systematic search in pubmed ( 17 april 2013 ) and scopus ( 17 april 2013 ) . the search strategy , which was utilised in both in pubmed and scopus databases , included the combination of key words : single incision and ( laparoscopic or laparoendoscopic or robotic ) and hepatectomy . the retrieved studies reporting data on the silh were regarded as includable for this review . letters to the editor , abstracts in scientific conferences , animal studies , editorials as well as studies published in languages other than english , german , greek , french , italian and spanish were not included in this review . we performed a systematic search in pubmed ( 17 april 2013 ) and scopus ( 17 april 2013 ) . the search strategy , which was utilised in both in pubmed and scopus databases , included the combination of key words : single incision and ( laparoscopic or laparoendoscopic or robotic ) and hepatectomy . the retrieved studies reporting data on the silh were regarded as includable for this review . letters to the editor , abstracts in scientific conferences , animal studies , editorials as well as studies published in languages other than english , german , greek , french , italian and spanish were not included in this review . we retrieved a total of 22 and 21 studies in pubmed and scopus search , respectively , among which 12 studies ( 12 case reports ) have met the inclusion criteria of our systematic review . the schematic representation of the adopted search strategy is depicted in figure 1 ( flow diagram ) . flow diagram of the detailed process of selection of articles for inclusion in the review the main characteristics of the studies included in our review ( demographics , medical history , clinical features of silh performed , operative parameters , outcomes ) are presented in table 1 . in our study , 30 patients in total were included . hepatitis infection ( 3 out of 30 , 10% ; type b , 2 out of 30 , 6.6% ; type c , 1 out of 30 , 3.3% ) , cirrhotic / chronic liver disease ( 3 out of 30 , 10% ) and previous history of neoplasia ( 7 out of 30 , 23.3% ) were the main co - morbidities reported among the included patients , while 20 out of 30 ( 66.7% ) patients did not have any co - morbidities at their medical history . the body mass index ( bmi ) of the included patients ranged from 20.1 to 36.5 kg / m . primary hepatic carcinoma ( 12 out of 30 , 40% ) , metastatic nodules ( 8 out of 30 , 26.7% ) , hepatic cyst ( 5 out of 30 , 16.7% ) , hepatic haemangioma ( 4 out of 30 , 13.3% ) and hepatic adenoma ( 1 out of 30 , 3.3% ) were the most common indications of the lesions resected . the types of hepatectomy performed included partial hepatectomy ( 13 out of 30 , 43.3% ) , segmentectomy ( 9 out of 30 , 30% ) and lobectomy ( 8 out of 30 , 26.7% ) . in the majority of the patients , left lateral segments ( ii - iii - iv ) ( 23 out of 30 , 76.7% ) were resected , while right lateral segments ( v - vi - vii - viii ) resection was performed in 7 out of 30 ( 23.3% ) . the size of lesion ranged from 7 to 300 mm . according the child - pugh classification , grade a were 18 out of 21 ( 60% ) , grade b were 2 out of 21 ( 9.5% ) , whereas grade c was present in only one patient ( 4.7% ) . regarding the utilised port system , sils port was used in 9 out of 30 ( 30% ) patients , 10 mm/5 mm trocars in 9 out of 30 ( 30% ) , gelport in 5 ( 16.7% ) , triport in 5 ( 16.7% ) and xcel port in 2 patients ( 6.6% ) . the size of incision varied from 12 to 40 mm , while the surgical free margin around the lesion ranged between 10 and 25 mm . main characteristics and outcomes of the patients after the performance of single incision laparoscopic hepatectomy the median operative time was 110 min ( range : 55 - 235 ) while the median quantity of blood loss was 50 ml ( range : 0 - 100 ) . none of the studies included described data on the cosmesis of the application of single incision laparoscopic technique on hepatic resections . the patients are placed in a reverse trendelenburg position and the surgeon 's position is between the patient 's open legs . through a supraumbilical vertical incision of 12 - 40 mm , the fascia is exposed and two absorbable stay sutures are applied into the fascia . a single - port device ( which permits the location of a high definition camera , two assistant ports and an insufflator cannula ) is safely and easily inserted into the abdominal cavity through the incision using a mayo - guyon clamp . pneumoperitoneum is induced by carbon dioxide insufflation through the specific single - port cannula , at a constant pressure of < 12 mmhg to prevent gas embolism . a high definition 30 laparoscope with a diameter of 5 - 10 mm is inserted throughout the single - port device in order to visualise the peritoneal cavity and then to introduce the rest of the instruments . then , an intra - operative ultrasonography is performed , through a 10 mm access port , with the intention to estimate the extension of surgical resection as well as the width of its possible safe margin . hepatic parenchymal transection is performed with the use of bipolar forceps and harmonic shears . during the process of the transection the resected specimen is extracted in a plastic bag from the abdominal cavity through the periumbilical hole after removing the single - port device . the patients are placed in a reverse trendelenburg position and the surgeon 's position is between the patient 's open legs . through a supraumbilical vertical incision of 12 - 40 mm , the fascia is exposed and two absorbable stay sutures are applied into the fascia . a single - port device ( which permits the location of a high definition camera , two assistant ports and an insufflator cannula ) is safely and easily inserted into the abdominal cavity through the incision using a mayo - guyon clamp . pneumoperitoneum is induced by carbon dioxide insufflation through the specific single - port cannula , at a constant pressure of < 12 mmhg to prevent gas embolism . a high definition 30 laparoscope with a diameter of 5 - 10 mm is inserted throughout the single - port device in order to visualise the peritoneal cavity and then to introduce the rest of the instruments . then , an intra - operative ultrasonography is performed , through a 10 mm access port , with the intention to estimate the extension of surgical resection as well as the width of its possible safe margin . hepatic parenchymal transection is performed with the use of bipolar forceps and harmonic shears . during the process of the transection the resected specimen is extracted in a plastic bag from the abdominal cavity through the periumbilical hole after removing the single - port device . the evolution of minimal invasive techniques has currently rendered laparoscopic surgery a valuable alternative to open surgical access . laparo - endoscopic single site surgery ( less ) and natural orifice transluminal endoscopic surgery ( notes ) are considered to be the most recent surgical methods . since 1992 , when pelosi et al . , first reported the realisation of laparoscopic appendectomy by the use of a single umbilical incision , a variety of surgical operations have been performed including hernias , nephrectomies , cholecystectomies , colestomies and splenectomies . in the past 10 years , technical issues , such as the absence of specifically designed port systems , the lack of particular articulating instruments , the instrumental crowding and clashing , the reduced visualisation , the loss of instrumental triangulation , have hold back the extensive utilisation of single port - surgical technique moreover , the lack of training programmes and the necessary learning curve have made such an operation the most commonly utilised single or multi - channel port devices include the sils port system ( covidien , mansfield , ma ) , the gelport ( applied medical , rancho santa margarita , ca ) , the triport ( advanced surgical concepts , wicklow , ireland ) and ordinary surgical ports ( 10-mm/5-mm trocars , kanger , tong lu , china ) . the sils port is a flexible port system , which necessitates an incision of 18 - 30 mm . the most important technical figure of sils port is the simple placement technique and the simultaneous collocation of one to three instruments at the same time through a single incision . in contrast , in case of large hepatic resections , the restricted dimensions of instruments require the removal of the port with the purpose to pass the removed specimen through the incision . the gelport system consists of a surgical wound retractor with a plastic inner ring joined to an outer ring with a clear cover , which can be applied in facial incisions between 15 and 70 mm . this particular type of port is suitable for single - port laparoscopy due to the presence of multiple positions for trocars with variable diameters that can without difficulty be modified . additionally , gelport can also be very useful in patients with deep abdominal wall ( more than10 cm ) . triport is also a multi - channel access ports , which has the capacity to maintain the pneumoperitoneum , even though there are variations in number instruments used during the operation . the triport system presents one 12-mm port and two 5-mm ports , whereas requires fascial incisions from 12 to 25 mm . moreover , the wide range of the angle at the various ports reduces the crowding of the instruments . the 10 cm of maximum depth that triport can be used , delimits the population of the patients . the utilisation of laparoscopic surgical ports with the use of conventional wound retractors does not impose any restriction at the diameter of the applied ports and at the dimension of the single incision . the major advantage of this method is that due to the fact that the location of the ports can be variable and can allow greater manipulation of the instruments , while in contrast , the removal of resected specimens necessitates a new facial incision permitting the loss of pneumoperitoneum . at present , laparoscopic hepatobiliary surgery represent a safe and valuable alternative for the management of liver disease in the hands of experienced surgeons . reduced morbidity , shorter hospital stay , less postoperative pain and the cosmetic advantage represent some of the potential benefits of single - port - access surgery [ table 2 ] . in patients with chronic liver disease , such as hepatic cirrhosis , a limited surgical trauma at the abdominal wall caused by single incision laparoscopic technique may be particularly useful by reducing the probability of bleeding , ascites , wound infections and/or incisional hernias . furthermore , the selection of the single incision and as consequence of the placement of the trocars is in correlation to patient 's body type and to the position of the lesions . as a result , the effectuation of a transumbilical port site with which a fine cosmetic result could be achieved is not always possible . in our review , no evidence was found regarding the cosmetic results , however , one could argue that in patients who are facing hepatectomy , cosmesis is the last issue to think compared with post - operative pain or complications . moreover , the most common motives for conversion to open laparotomy can include bleeding not otherwise treated , poor localisation of the neoplasia or else positive tumour margins and last but not the least slow progression during the liver parenchymal transection . in our study , no conversions were described probably due to the reduced number of patients included and perhaps because of the innovation of the technique the surgeons were more conservative with the resections . in contrast , the rates of conversion in multiple laparoscopic surgery are considered relatively low . the absence of complications or death of patients related to single port technique were comparative to quite low incidence at the classic laparoscopy . even though , the continuous development of new port systems and laparoscopic instrument is distinctive , there are some technical problems in operating through a single port that should be taken into account . the instrument crowding as well as the absence of triangulation are among the most frequent technical issues . therefore , the range of movements is restricted due to the proximity of the instruments . this problem could be solved by various means . however , this can cause counterintuitive movements as the surgeon manoeuvres the instruments on the reverse side of the abdominal cavity . furthermore , the utilisation of surgical ports with large outer cap , such as the gelpoint , is in position to increase the instrument distance . last but not the least , in traditional laparoscopy , the effect of triangulation consists in an important condition in order to provide the minimal necessary flexibility for rigid instruments and ports that provide minimal flexibility . in contrast , the existence of a single port for both the camera and the laparoscopic instruments eliminate the effect of triangulation . the use of proximally curved coaxial instruments with double bending ( s - portal curved instruments , karl storz gmbh & co. kg ) allows the crossing over of the instruments and permits their proper triangulation . possible advantages and disadvantages in the utilization of single site port hepatectomy according to the included studies , there is little evidence on the learning curve of the single port technique . in order to familiarise , especially the young surgeons , with this surgical novelty , the development of training programmes that combine the use of simulators with animal or cadaver models is necessary additionally , one of our recommendation before a surgeon gain sufficient experience on silh is to practice , at least at the beginning , liver resections of limited expansion mainly at peripherally located lesions , then move to anatomical resections ( such as segmentectomies ) and at last to proceed at major hepatectomies . the application of sils is also characterised by some patient - related restrictions . the utilisation of umbilicus as the entry point of the single trocar limits the number of patients who are suitable candidates for sils derived from the patient 's bmi . this obstacle can be overcome by using 8-mm instead of 5-mm ports in addition to a camera at 30 degree up or down with the purpose to avoid instrument crowding . additionally , the possible use of flexible endoscopes may also increase visualisation of the surgical field . a further disadvantage of the technique is the fact that the various movements of the laparoscopic instruments may create gas leaking from some port systems , reducing in this way the necessary pneumoperitoneum necessary to carry out the operation . a query could also be raised on whether there is an increased probability of port site metastasis in patients with gas air leak as the follow - up period is not adequate till now to clarify such a possibility . at this point , various limitations should be taken into consideration in the elaboration of the findings of this study . the small numbers of the included studies as well as the small number of the total patients included in these studies are confirming the fact that the application of single incision laparoscopic technique on liver resections is a novelty that is in evolution . potential indications as well as contraindications of the single incision method need to be additionally clarified . furthermore , randomised control trials or at least case series with better methodological quality are necessary not only to standardise this technique but also to compare the complication rates between the multi - port and open surgical methods . lastly , regarding our search strategy , even though it has a broad range , it could be considered limited due to the exclusion of letters , abstracts , editorials and animal studies . in conclusion , single site port laparoscopic surgery is a promising minimally invasive procedure , which along with the development of the existing technology , may be able to impose this kind of technique in various surgical fields as a common practice . in particular , in liver surgical practice , the existing evidence on the use of single incision laparoscopy appears to be promising . nonetheless , more studies with better methodological quality are necessary to be done in order to define better the limits of silh . the continuous improvement on the development of medical instruments , in addition to the increasing clinical experience , can define the conditions that guarantee the safety and feasibility of single incision surgery .
single incision laparoscopic surgery is a rather innovative surgical technique . 
 a systematic literature review was performed with the intention to evaluate the till now clinical evidence regarding the application of single incision technique on liver resections as a method of management in hepatic lesions . 
 twelve relative studies were found in the field including 30 patients with a age range from 29 to 90 years and a body mass index from 20.1 to 36.5 kg / m2 . 
 primary hepatic carcinoma ( 40% ) , metastatic nodules ( 26.7% ) , hepatic cysts ( 16.7% ) , hepatic haemangiomas ( 13.3% ) and hepatic adenoma ( 3.3% ) were the most common indications of the lesions resected . 
 the types of hepatectomy performed included partial hepatectomy ( 43.3% ) , segmentectomy ( 30% ) and lobectomy ( 26.7% ) . in the majority of the patients , left lateral segments ( ii - iii - iv ) ( 76.7% ) were resected . 
 the median operative time was 110 min ( range : 55 - 235 ) while the median quantity of blood loss was 50 ml ( range : 0 - 100 ) . 
 no conversion to open surgery and no transfusion were needed . 
 the duration of hospital stay ranged between 2 and 11 days . 
 no complications , no cases of disease recurrence or death of patients were reported . 
 none of the studies included described data on the cosmesis of the application of single incision laparoscopic technique on hepatic resections . moreover , the surgical technique , as well as the different type of ports used is also presented in this review . 
 single site port laparoscopic surgery is a promising minimally invasive procedure for liver resections .