For this prospective cohort study, 158 consecutive patients with benign adnexal diseases who were treated with LESS from March 2013 to December 2015 at our institution were enrolled into a prospective registry designed to assess perioperative outcomes. The registry study was approved by the Institutional Review Board (KUH1040039). Data was accessed anonymously. Inclusion criteria are planned LESS for benign lesions, age ≥18 years, and American Society of Anesthesiologists (ASA) score 1 or 2. Patients were divided into 2 groups, chronologically. From March 2013 to August 2014, 82 patients who underwent LESS did not receive local bupivacaine injection into the incision site and were assigned to group 1. Thereafter to December 2015, an additional 76 consecutive patients who underwent LESS received bupivacaine injection. We evaluated demographic, clinicopathological, and follow-up data of all patients. Each patient underwent preoperative laboratory evaluation including serum cancer antigen-125, physical examination, and pelvic ultrasound or computed tomography.

All surgeries were performed by a single surgeon (SH Shim). After general anesthesia, the patient was placed in the dorsal lithotomy position. A Cohen cannula was used for uterine manipulation and was handled by the second assistant. An approximately 2 cm intraumbilical skin incision was made, and a single port device (Glove port; Nelis, Bucheon, Korea) was installed transumbilically. Rounded distention of the abdomen after initial pneumoperitoneum was made adequately. The adnexal surgeries were performed with the monopolar or bipolar forceps, atraumatic forceps, scissors, toothed grasper, and a suction-irrigator. The tissue was placed in a 10 mm endobag and removed from the pelvic cavity via the 20 mm incision site. The inserted single port device was removed from the abdominal wall. Group 1 did not receive local injection and group 2 received 10 mL of 0.25% bupivacaine (100 mg) into the 20 mm trocar incision site at the end of LESS. Injecting the local anesthetic through all preperitoneal layers provided a full-thickness local injection. Bupivacaine (0.25%) was injected with a 22G needle. The fascia of the 20 mm puncture site was closed layer by layer with a 2-0 polyglactin suture (Vicryl, Ethicon Inc., Somerville, NJ, USA). The skin was closed by interrupted sutures with 3-0 resorbable monofilament suture (Monosyn, B. Braun, Melsungen, Germany).

Postoperative pain therapy was composed of either intravenous narcotics via patient-controlled analgesia and/or nonsteroidal anti-inflammatory oral pain medication per the standard postoperative pain medication protocol used at our center. Whenever a patient requested additional analgesics, meticulously registered parenteral analgesics (tramadol hydrochloride, 50 mg intravenously) were given. A 5-day discharge course of thrice-daily oral nonsteroidal anti-inflammatory drugs was dispensed. The postoperative instructions included the specific recommendation to avoid sexual intercourse for 2 weeks after the procedure. The first ambulatory visit was at 1 month after discharge and included an assessment primarily on the surgical wound state and a general physical examination. The patient was asked about food tolerance, the presence of fever, dyspareunia, and evolution of postoperative pain. Subsequent follow-up visits were scheduled at 6 months and 1 year after the surgery and included a physical examination and transvaginal ultrasonography.

The primary outcome was postoperative pain assessed using the visual analog scale (VAS). The secondary outcomes were operating time (initial incision to skin closure), estimated blood loss, transfusion, change in hemoglobin (from before the surgery to the first postoperative day), additional analgesic requirements, and perioperative complications. To evaluate postoperative pain, the patients were asked to rate the intensity of pain using a VAS ranging from 1 (absence of pain) to 10 (worst pain possible) immediately after the surgery in the recovery unit and at 3, 8, 16, and 24 hours after surgery [14]. A registered nurse queried patients about their pain on a regular schedule. To measure blood loss, the aspirator and blood-absorbent gauze were collected and weighed, and the weight of the lost blood was estimated by subtracting the weight of the intact gauze from the total measured weight. Perioperative complications were defined as any adverse event requiring additional medical or surgical therapeutic interventions during surgery and within 30 days after surgery.

The sample size was calculated before study initiation. This hypothesis was defined by comparing the mean VAS pain scores between the 2 groups. A mean difference between the 2 groups of 2 VAS pain scores was deemed clinically relevant, and the standard deviation was expected to be 3.5, based on the previous published report [17]. Given these assumptions, a sample size of 65 subjects per group provided 90% statistical power to detect a mean difference of 2 VAS pain scores points between the groups at any given time point using a 2-sided test having a significance level of 0.05. Taking into account for potential loss of patients to follow-up, a total of 158 patients were recruited.

Normally distributed continuous variables were presented as means (standard deviations). Non-normally distributed variables were presented as medians (ranges or interquartile ranges). Mean values between the groups were compared using Student's t-test for normally distributed data or the Mann-Whitney U-test for non-normally distributed data. Frequency distributions were compared using a χ² test or Fisher's exact test. A P-value <0.05 according to 2-sided tests indicated a significant difference. All analyses were performed using SPSS, version 19.0 (SPSS Inc., Chicago, IL, USA).