over recent years , laparoscopic surgeries have already been demonstrated as a better alternative to open abdominal surgery , especially when treating benign diseases .
intraoperative complications , pain , and length of postoperative hospital stay have all been found to be reduced .
many attempts have been made to minimize the number of trocars by applying single port laparoscopic surgery ( spls ) to perform a cholecystectomy , appendectomy , and splenectomy .
spls has also been applied to perform hysterectomies by several gynecologic groups with improving effects .
however , few studies have evaluated the potential benefits of spls for the treatment of benign adnexal masses ; therefore , in this study , our objective was to assess the feasible advantages of spls via a comparative analysis between spls and conventional laparoscopy for adnexal masses .
this study was a case - control study that compared the outcomes of 99 cases of spls and 104 conventional laparoscopic adnexal procedures for adnexal masses between december 2013 and march 2015 performed by a single surgeon .
the 99 patients who were chosen to undergo spls were those with the diagnosis of benign adnexal mass .
the 104 patients in the control group who underwent conventional laparoscopic adnexal surgery , were age - matched and chosen during the same period .
the inclusion criterion for both groups was as follow : patients who were diagnosed with the presence of adnexal masses on ultrasonography and without any severe complications . patients who were under suspicion of malignant ovarian tumor on ultrasonography or with severe complications that can not withstand surgery were excluded .
the patients clinical data for both groups including history , routine preoperative workup , such as blood routine , biochemistry , coagulation tests , tumor markers , electrocardiogram , and chest x - ray were all collected retrospectively .
all surgeries were performed by a single surgeon ( ling yin ) , with the assistance of two surgeons ( yan zhang and bing - bing xiao ) , at a single institution ( peking university first hospital ) .
the postoperative assessment was performed by a single investigator ( si - yun wang ) .
the spls port with three access ports ( one 12-mm port and two 5-mm ports ) as well as a gas inlet , which was produced in tonglu , hangzhou , china , was used .
after surgeries , intraoperative data including the operation time ( from skin incision to closure ) , estimated blood loss ( ebl ) ( by visual and experiential estimation ) , change in hemoglobin level after surgery ( recorded at 3 days postoperatively ) , duration of postoperative hospital stay , intraoperative and postoperative complications were all collected until 1 month follow - up postoperatively . after a 23 cm
transverse transumbilical incision was made , an spls port wound retractor ( 30 mm ) , which was composed of a distal ring , a proximal ring , and a cylindrical connecting sleeve , was then inserted to expand the edge of the incision laterally .
the spls port has three access ports ( one 12-mm port and two 5-mm ports ) as well as a gas inlet .
we used a rigid , 30 , 10-mm laparoscope , traditional rigid straight instruments , and prebent laparoscopic instruments to prevent the instruments from clashing and to optimize the operation space [ figure 1 ] .
( b ) the spls port has one 12-mm port and two 5-mm ports as well as a gas inlet .
( c ) using a rigid , 30 , 10-mm laparoscope , traditional rigid straight instruments , and prebent laparoscopic instruments to optimize the operation space .
once all equipment were in position , the following procedures were similar to the techniques in conventional laparoscopic approach [ figure 2 ] .
the skin was closed using a 3 - 0 vicryl suture ( johnson & johnson , usa ) , which provided for a good cosmetic outcome [ figure 3 ] .
intraoperative view of a single port laparoscopic surgery for the treatment of an adnexal mass .
( d ) postoperative image . a representive image of the 23 cm incision for the single three - channel port system prior to the final skin closure .
the spss version 20.0 ( spss inc . , chicago , il , usa ) was used for statistical analysis using the student 's t - test , fisher 's exact test , chi - square test , and wilcoxon rank sum test .
quantitative data that satisfy a normal distribution were analyzed using student 's t - test ( data are shown as mean  standard deviation [ sd ] ) .
quantitative data that did not satisfy a normal distribution were analyzed using wilcoxon rank sum test ( data are shown as median [ min , max ] ) .
qualitative data were analyzed using fisher 's exact test and chi - square test ( frequency [ % ] ) . a value of p < 0.05 was considered as statistically significant .
after a 23 cm transverse transumbilical incision was made , an spls port wound retractor ( 30 mm ) , which was composed of a distal ring , a proximal ring , and a cylindrical connecting sleeve , was then inserted to expand the edge of the incision laterally .
the spls port has three access ports ( one 12-mm port and two 5-mm ports ) as well as a gas inlet .
we used a rigid , 30 , 10-mm laparoscope , traditional rigid straight instruments , and prebent laparoscopic instruments to prevent the instruments from clashing and to optimize the operation space [ figure 1 ] .
( b ) the spls port has one 12-mm port and two 5-mm ports as well as a gas inlet .
( c ) using a rigid , 30 , 10-mm laparoscope , traditional rigid straight instruments , and prebent laparoscopic instruments to optimize the operation space .
once all equipment were in position , the following procedures were similar to the techniques in conventional laparoscopic approach [ figure 2 ] .
the skin was closed using a 3 - 0 vicryl suture ( johnson & johnson , usa ) , which provided for a good cosmetic outcome [ figure 3 ] .
intraoperative view of a single port laparoscopic surgery for the treatment of an adnexal mass .
( d ) postoperative image . a representive image of the 23 cm incision for the single three - channel port system prior to the final skin closure .
the spss version 20.0 ( spss inc . , chicago , il , usa ) was used for statistical analysis using the student 's t - test , fisher 's exact test , chi - square test , and wilcoxon rank sum test .
quantitative data that satisfy a normal distribution were analyzed using student 's t - test ( data are shown as mean  standard deviation [ sd ] ) .
quantitative data that did not satisfy a normal distribution were analyzed using wilcoxon rank sum test ( data are shown as median [ min , max ] ) .
qualitative data were analyzed using fisher 's exact test and chi - square test ( frequency [ % ] ) . a value of p < 0.05 was considered as statistically significant .
the clinical characteristics between the two groups did not differ significantly , including the size of adnexal masses showed on ultrasonography and the proportion of unilateral masses [ table 1 ] .
a cystectomy with or without concomitant surgeries such as myomectomy or hysteroscopy was performed in 76.7% of the spls group and in 77.9% of the conventional group , which was not a remarkable statistical discrepancy .
the adhesiolysis ratio also showed no obvious difference between the two groups ( spls : 65.7% ; conventional : 67.3% ; p = 0.803 ) ; however , the pathological findings between the two groups were slightly different . in the spls group ,
mature cystic teratoma made up the vast majority of pathological types while endometrioma was more commonly observed in the control group [ table 2 ] .
comparison of preoperative characteristics of the single port laparoscopic surgery group and the conventional group * the size of ovarian tumors was measured by transvaginal ultrasonography ; u value ; t value ;  value ; spls : single port laparoscopic surgery ; bmi : body mass index ; sd : standard deviation ;  : no data .
comparison of operative characteristics of the single port laparoscopic surgery group and the conventional group , n ( % ) * other procedures included myomectomy , hysteroscopy + fractional curettage , hysterectomy and appendectomy ; other benign tumors included hydrosalpinx , ovarian corpus luteum cyst , mesosalpinx cyst , myoma , ovarian steroid cell tumor , ovarian thecoma , ovarian granulosa cell tumor , tubal serous glands fibroma ;  value ; spls : single port laparoscopic surgery ;  : no data .
no remarkable difference was shown between the two groups regarding the median operation time ( 51 min vs. 52 min , p = 0.909 ) , median postoperative duration of hospital stay ( 3 days vs. 3 days , p = 0.168 ) and the median change in hemoglobin level ( 10 g / l vs. 10 g / l , p = 0.795 ) from preoperation to postoperation day 3 .
notably , in spls groups , the median ebl and the anal exsufflation time were significantly less than those of the conventional group ( 5 ml vs. 10 ml , p < 0.001 ; 10 h vs. 22 h , p < 0.001 ) .
there were no complications in either group , including peripheral visceral injury , incision hernia , or other postoperative morbidity .
comparison of operative outcomes of the single port laparoscopic surgery group and the conventional group data are shown as median ( min , max ) .
spls : single port laparoscopic surgery ; ebl : estimated blood loss ; pod : postoperative duration of hospital stay . based on visual inspection of the learning curve of the operation time from the 1 case to the 99 case in the spls group , the operative time gradually shortened as more cases were performed . a significant decrease in time
was noted after 12 cases were done [ figure 4 ] . in the control group ,
operative time from the first case to 99 case in the single port laparoscopic surgery group .
spls is a highly innovative technique that has been introduced in the field of minimally invasive surgery in recent years . although spls technique has been reported to perform tubal ligation for the 1 time in the 1970s , and ghezzi et al .
succeeded in performing salpingectomy using spls in 2005 , the use of spls technique has not been widespread because of its technical challenges .
fortunately , the innovation of operative techniques and design of new devices to overcome such difficulties have generalized the application of spls .
several gynecologist groups have reported successful experience in diverse gynecological procedures using spls approaches such as laparoscopic - assisted vaginal hysterectomy and total laparoscopic hysterectomy .
we performed a retrospective study to assess the use of spls versus conventional laparoscopy for the treatment of benign adnexal masses during the same period . considering that the patients enrolled in our study
. this might lead to the difference of the baseline characteristics and the variety of diseases between the two groups . according to our data ,
the median age of the patients from both groups were equal ( 32 years vs. 32 years , p = 0.055 ) , but the variation in the spls group was slightly smaller than that of the conventional group ( [ 11 years , 58 years ] vs. [ 15 years , 73 years ] , p = 0.055 ) .
moreover , the size of the ovarian tumor in the spls group was slightly smaller ( 49.0 mm vs. 55.5 mm , p = 0.064 ) .
however , there was no statistically significant difference between the two groups regarding these two indicators .
besides , from clinical experience , factors including body mass index , history of previous abdominal surgery and severity of pelvic adhesion were considered more relevant than age itself to the surgical outcomes and complications .
furthermore , we believe the insignificant difference between the ovarian tumor size of the two groups was quite insignificant for experienced surgeons in clinical practice and would not have a dramatic influence on the main surgical outcomes .
we concluded that no significant differences were observed regarding the operation time , perioperative decrease in hemoglobin level and postoperative hospital stay between the two groups . in the spls group ,
the median ebl was 5 ml and the median exsufflation time was 10 h. both outcomes were superior to those of the conventional group ( p < 0.001 ) .
there were no cases of peripheral visceral injury or conversion to conventional laparoscopic surgery or laparotomy .
additionally , there was a notable difference in the pathological types between the two groups ( p = 0.002 ) . in the spls group ,
mature cystic teratoma was the majority pathology type , comprising 27.8% of all cases . meanwhile , endometrioma made up 40.4% of the cases in the control group .
this significant difference might have some influence on the surgical outcomes between the two groups , such as operation time and ebl due to pelvic adhesions that endometriomas commonly cause . however , there were no assumed differences in either the ratio of adhesiolysis performed during surgery or the operation time in both groups according to our study .
the ebl in spls group was significantly less than that in the conventional group ( 5 ml vs. 10 ml , p < 0.001 ) , but it did not have any dramatic impact on the median changes in hemoglobin levels postoperatively ( spls : 10
g / l ; conventional : 10 g / l ; p = 0.795 ) .
therefore , we consider the difference in the pathology types between the two groups to be minor as it did not influence the operative outcomes in our study .
however , our short - term follow - up was not able to validate long - term complications between the two groups .
several previous reports have reached similar conclusions that the surgical outcomes in benign adnexal surgeries did not differ significantly between spls and conventional laparoscopy . in our study
the size of the ovarian mass was 70 mm  56 mm  51 mm .
these positive results suggest that even in emergency cases like ovarian cyst torsion , spls might also have comparable surgical outcomes compared to conventional laparoscopic surgery .
therefore , we would like to share our successful experience to draw more attention to single port procedures to manage benign adnexal masses .
it is fundamental to maintain triangulation during spls procedures to avoid excessive instrument clashing and provide sufficient surgical field exposure .
however , it is challenging because all of the laparoscopic working ports are placed through the same incision . in our experience , we used a 10-mm , 30-cm endoscope with a 30 angle to provide a wider range of vision and avoid collisions between surgical instruments compared with 0 endoscopes .
we further used small trocars and prebent laparoscopic instruments to avoid collisions between instruments and to provide a wider range of motion . in spite of the above challenges ,
first , a single incision at the umbilicus might offer superior cosmetic outcomes by taking advantage of the concealing location of the umbilicus to hide the scar .
second , it was easier to extract the specimen through a larger umbilical incision expanded by the spls wound retractor compared to the conventional 5-mm or 11-mm trocar incisions . third , by eliminating the trocars inserted in the bilateral lower quadrant the risks of complications including injury to the inferior epigastric vessels , subcutaneous hematoma as well as postoperative wound infection might be reduced .
fourth , spls might be associated with less postoperative pain and the reduction of narcotic use due to few trocars being inserted .
controversially , a larger umbilical incision may also cause a greater amount of postoperative pain .
kim et al . demonstrated less postoperative pain score in the spls group for hysterectomy than that of the conventional group with comparable surgical outcomes .
nevertheless , studies that compare levels of postoperative pain between the two groups are warranted .
others include the costs of certain instruments , increased risk of complications including a hernia and possible increased postoperative pain associated with the larger size of the incision
. however , the risk of a hernia does not appear to increase with the spls approach when the fascia is closed in a running , mass closure fashion .
there were foreign researches reported that additional spls instruments would raise surgical costs . however , the spls ports we used were domestic products which hardly increased the surgical costs .
still , the generalizability of spls technique requires additional effort and time to learn the operative skills .
have demonstrated a remarkable decrease in operative time after 1015 spls were performed . according to our experience , proficiency in the learning curve
as our surgeon is very experienced and has performed laparoscopic surgeries for more than 20 years , adopting spls technique for her was not as much of a challenge compared to junior physicians .
thus , we did not expect a significantly prolonged operation time in the spls group . as a matter of fact ,
the operative time shortened as more cases were performed , compared to the control group , in which the operative time remained steady .
in addition , the operative time in spls might also be shortened due to the easier extraction of the specimen as we mentioned earlier .
as surgeons gain experience , the difference between the two groups regarding necessary operation time becomes insignificant .
although we have concluded that spls approach has comparable surgical outcomes compared to conventional laparoscopic surgery regarding treating benign adnexal masses , as the operation type gets more complicated , spls approach might be confined by its complex technical challenge .
therefore , despite that spls technique might have several advantages , it can not replace conventional laparoscopic approach in complex cases .
studies that evaluate the feasibility and safety of spls for adnexal masses are not adequate .
most of the previous studies have been limited to retrospective data and small samples of patients . in spite of the limitations of the study , including a retrospective data comparison with inevitable case selection bias and lack of postoperative pain score measurement and long - term follow - up
, we have concluded that spls is a safe and feasible approach to treat benign adnexal masses .
prospective studies with postoperative pain score measurement and long - term follow - up are needed to further assess the potential benefits and defects of spls .
 background : single port laparoscopic surgery ( spls ) is an innovative approach that is rapidly gaining recognition worldwide . the aim of this study was to determine the feasibility and safety of spls compared to conventional laparoscopic surgery for the treatment of benign adnexal masses.methods:in total , 99 patients who underwent spls for benign adnexal masses between december 2013 and march 2015 were compared to a nonrandomized control group comprising 104 conventional laparoscopic adnexal surgeries that were performed during the same period . 
 we retrospectively analyzed multiple clinical characteristics and operative outcomes of all the patients , including age , body mass index , size and pathological type of ovarian mass , operative time , estimated blood loss ( ebl ) , duration of postoperative hospital stay , etc.results:no significant difference was observed between the two groups regarding preoperative baseline characteristics . 
 however , the pathological results between the two groups were found to be slightly different . 
 the most common pathological type in the spls group was mature cystic teratoma , whereas endometrioma was more commonly seen in the control group . 
 otherwise , the two groups had comparable surgical outcomes , including the median operation time ( 51 min vs. 52 min , p = 0.909 ) , the median decreased level of hemoglobin from preoperation to postoperation day 3 
 ( 10 g / l vs. 10 g / l , p = 0.795 ) , and the median duration of postoperative hospital stay ( 3 days vs. 3 days , p = 0.168 ) . in spls groups , 
 the median ebl and the anal exsufflation time were significantly less than those of the conventional group ( 5 ml vs. 10 ml , p < 0.001 ; 10 h vs. 22 h , p < 0.001).conclusions : spls is a feasible and safe approach for the treatment of benign adnexal masses . 
 further study is required to better determine whether spls has significant benefits compared to conventional techniques . 
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Operative techniques
Statistical analysis
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