This is the first study on tubal sterilization describing a gasless single-incision laparoscopic technique in which the intra-abdominal vision is maintained following the elevation of the abdominal wall by using surgical ropes. All the operations were performed by the same surgical team and under the same operative theatre conditions. Although the study included a limited number of participants, the included groups had similar demographic, physical, and medical characteristics.

One third of the complications of CO2 laparoscopy occur during pneumo-peritoneum creation or trocar instillation by the blind introduction of the Veress needle or trocars into the abdominal cavity [9]. Because KARS is an open laparoscopic technique, the chance of visceral injury occurring is minimal.

KARS is a gasless laparoscopic technique which protects the patient from the pneumo-peritoneum associated side effects like hypercapnia, acidosis, gas embolism, pneumothorax, subcutaneous emphysema, deep venous thrombosis, instability of the hemodynamics, decrease in renal functions, and peritoneal oxidative stress [5–7, 10, 11, 19–21]. Gasless surgery is also more optimal for regional anesthesia. However, longer operative time and patient position limit the use of regional (spinal and epidural) anesthesia in KARS [16].

In CO2 laparoscopy, trocars with valves are needed to maintain the created pneumo-peritoneum during surgery. Laparoscopic hand instruments are used through trocars to prevent gas leakage and maintain intra-abdominal high pressure [22]. However, in KARS the abdominal wall is elevated with surgical ropes, and neither the intra-abdominal gas nor the trocars for maintaining vision of the operative field are required. Trocars generally need a 1 mm larger diameter (20% for a 5 mm diameter and 10% for a 10 mm diameter) than the instruments employed, and the extra abdominal part of the trocars, containing valves and locks, are even larger. In contrast, KARS’ trocar-less entry, by sparing more space, allows for multiple instrument entry through the same single access route. In addition, the hand instruments do not need to fit with anything other than the incision. This characteristic also allows the use of conventional surgical instruments used in conventional laparotomy. Moreover KARS allows demanded amounts of irrigation and aspiration without decreasing the intra-abdominal space blurring the vision.

The fixed working envelope around each port often necessitates multiple ports to accommodate changes in instrument position for improved visibility and efficiency. However, additional ports contribute to post-operative pain, diminish cosmesis, and carry a risk of bleeding, hernia formation, or organ damage. In addition, the special ports used in single incision surgeries have limited access holes. One of the access holes is for the telescope, and in general there are only two holes for hand instruments [15, 23, 24]. KARS is a single-incision surgery and has all of the advantages of the single-incision surgery. In this manner, KARS also has the advantage of permitting the use of multiple instruments at the same time. (During some operations we used 3 hand instruments and the telescope at the same time.)

In conventional laparoscopy the ports are rather too small in diameter to handle them with conventional surgical instruments and thus some surgeons do not close the facial layer of the abdominal wall if 10 mm trocars are used. Almost all surgeons do not close the facial layer if 5 mm trocars are used which may lead to hernia formation. However in KARS the facial layer is prepared for closure at the initial stage of the construction of the abdominal access pathway. The fascia is elevated and stitched easily as in usual open surgery.

4.3. Limitations of the Study and KARS

Although our retrospective study included groups with similar demographic characteristics (, Table 1), it lacks the power of a prospective randomized study.

This retrospective case controlled study was performed in a single center by the same surgical team. Although it is useful for creating a homogeneous perioperative condition to compare the findings of both surgical techniques, the comparison of the surgical teams with different levels of surgical skills is lacking.

At the beginning of 2010 laparoscopic surgery was not a routine application for the surgical management of gynecologic disorders in our department. Initially we built a laparoscopic surgery team and began to perform laparoscopic surgery. Although the team members had some experience on laparoscopic surgery, the harmony among individual team members was lacking. Thus, the team’s surgical skills and harmony were not at an advanced level for KARS and/or conventional laparoscopy.

The limited number of cases was not adequate to study appropriately the learning curve of KARS (Table 3). Although, following the first 15 cases, the means of operation time and abdominal cavity access time decreased, the same decreases were also observed in conventional CO2 laparoscopy group. This finding might represent a better orientation of the surgical team to both operation techniques in time. In order to better study the learning curve of KARS the study should be repeated by a better-organized and more experienced surgical team.

Because the women with previous abdominal operations and dense intra-abdominal adhesions were excluded, our study cannot evaluate the feasibility of KARS in women with dense intra-abdominal adhesions.

Our study reflects the results of tubal sterilization at the end of the second year. However the rate of the success of the tubal sterilization in a longer time period is not known. In addition, the number of included women  is not sufficient for conclusions that can be applied to the whole population. The reader should note that the study mainly deals with the operative techniques.

KARS has the same common disadvantages of any single-incision laparoscopic surgery like sword fighting of the instruments and the telescope, obstruction of the operative field by a hand instrument passing in front of the telescope, and the difficulty of the manipulation of the instruments introduced parallel. In addition, the trocar-less entry causes more frequent contamination from incision edges, and the telescope needs to be cleaned more frequently [16].

In KARS, the partial elevation of the upper abdominal viscera results in a smaller space which may cause difficulties to hold most of the bowel out of the operative field adequately. Our previous study demonstrated that increasing the upper abdominal space with the stitches placed through the overlying skin of the supraumbilical region removes the bowels to the upper abdominal cavity adequately [16]. However, we did not need to use the additional sutures during tubal sterilizations. The vaginally placed uterine manipulator provided the uterine elevation, thus the adequate visualization of the tubes.

KARS is a modified technique that employs the features of laparoscopy and laparotomy which necessitates the familiarity of the surgeons with both techniques. However, the abdominal access technique has similarities with the laparotomy and is conducted under direct vision. The elevation procedure is simple and any surgeon familiar to laparotomy can perform it easily and swiftly after a few procedures.

4.4. Comparison with the Previous Studies and Techniques

Beginning from 1993 gasless (isobaric) laparoscopic surgery has been defined and used for a wide variety of gynecological surgical procedures [25, 26] such as myomectomy [27–29], hysterectomy [18, 30], ovarian cyst resection [16–18, 31], colposuspension [32], and radical hysterectomy [33]. In all operations special surgical instruments, such as a special device with an abdominal retractor, a subcutaneous lifting device, or an airlift balloon retractor, have been used to elevate the abdominal wall. However, in KARS only the usual conventional surgical materials and instruments were used for the lifting process [16–18].

Laparoendoscopic single-site (LESS) surgery is used to describe various surgical techniques that aim to perform laparoscopic surgery through a single incision [23]. LESS has gained world-wide popularity since 2005 and various operations including gynecological cancer staging, salpingo-oophorectomy, ovarian cystectomy, laparoscopy assisted vaginal hysterectomy, and laparoscopic total hysterectomy have all been performed by using LESS [33–38]. LESS procedures used two (or more) conventional ports or a single multichannel device (which enables the passage of instruments and optics) placed in a single incision. Although some multichannel devices had ports for three instruments and an optic [39], most of the time the conventional trocars and multichannel devices allow for only a limited numbers of instruments to be used. In contrast, with its trocar-less access property KARS provided more space for instruments and the optic within a similar-sized incision. In addition, it spares the additional cost of the special access ports. Moreover, the conventional surgical instruments (with stronger jaws) fitting with the incision could also be used if needed [16–18].

The mean operative time of laparoscopic tubal sterilizations varied between 20 and 25 minutes [40, 41]. It might depend on the subjective conditions of the operative theatre and the subjective qualification of the surgical team. In our study, the mean operation time for conventional laparoscopic tubal sterilization and KARS was not significantly different  as  and  minutes, respectively (Table 2). However the mean abdominal cavity access times of  for conventional laparoscopy and  for KARS were significantly different . The discordance of the findings may result from the easier closure of the abdominal access pathway in KARS. The preprepared facial sutures helped to close the umbilical incision of KARS. In contrast, the facial suturing and closure was harder in conventional laparoscopy.

During laparoscopic sterilization the tubes may be occluded by various methods including electrosurgical methods using unipolar or bipolar electrocoagulation or mechanical methods such as the Hulka-Clemens spring clip, the Filshie hinged clip, or the Falope or Yoon silastic ring/band [42]. US Collaborative Review of Sterilization Study (CREST) [43] found that the efficacy of tubal sterilization varied by the patient’s age, race, and ethnicity. In addition, the lowest postprocedural pregnancy rates were achieved following unipolar coagulation and postpartum partial salpingectomy. Bipolar tubal coagulation was also found highly effective where the tubal coagulation was adequate [44]. In our study, we performed a partial salpingectomy by using laparoscopic bipolar cautery and scissor, and a 5 to 10 mm portion of the tube was removed. At the end of the second year none of the women got pregnant.

Depending on the findings of our study KARS procedure seems feasible for tubal sterilizations. However, the reader should note that the limited number of the participants and time of the follow-up period of our study necessitate further prospective studies consisting of larger serious with longer follow-up periods.