Transperineal minimally invasive APE: preliminary outcomes in a multicenter cohort

A consecutive cohort of patients who underwent TpAPE for primary rectal cancer was identified at five centers (two in The Netherlands, one in Taiwan, one in Canada, and one in the United Kingdom). This group consisted of patients that had either a bilateral ELAPE, an unilateral ELAPE or APE with resection of the entire external sphincter [31, 32]. Intersphincteric APE’s were excluded. A retrospective analysis of prospective institutional databases was performed, and individual patient data were provided by an anonymized data sheet. The annual volume of rectal cancer surgery varied amongst the participating centers, but all perform over 50 resections (including transanal minimally invasive local excision, partial mesorectal excision, low anterior resection, APE, ELAPE, and recurrent rectal cancer).

The patient is placed in a lithotomy position to enable simultaneous abdominal and perineal dissection. The abdominal phase is performed by a standard laparoscopic medial to lateral mobilization of the left colon. The inferior mesenteric vein is ligated near the lower border of the pancreas and the inferior mesenteric artery ligated with preservation of the left colic artery. The mesorectal plane is opened with autonomous nerve preservation and dissection is continued up to connection with the perineal team. The perineal phase commences with a purse string closure of the anus. Afterwards, a radial perineal incision at approximately 1 cm from the closed anus is made into the subcutaneous fat. A single port can be inserted after creating a 2–3 cm deep opening of the ischioanal fat around external sphincter and connected to a continuous high flow insufflation and smoke exfiltration system. The most frequently used single port devices are the Gelpoint Mini and Gelpointh path (Applied Medical, Rancho Santa Margarita, California, USA). Standard laparoscopic instruments including a diathermic hook or spatula are needed for the endoscopic perineal phase. Dissection continues cephalad until the pelvic floor (levator ani muscle) is reached. Continuation externally along the levator ani muscle is tailored on a case by case level. For uni- or bilateral ELAPE procedures, the pelvic floor is followed on one or both sides up to the fascia of the obturator internus muscle and transected at this level. For a standard APE, the pelvic floor is usually transected a few centimeters out from the puborectal sling. The transection usually starts at the level of the coccyx and thereafter going forward. By cutting the pelvic floor muscle, and the overlying pelvic floor fascia connection is made with the abdominal team without coning in on the tumor. Identification of the correct anterior plane, remains the most difficult step. It is crucial to identify the transverse perineal muscles to enter this plane just posteriorly to these muscle fibres to find the avascular plane in front of the posterior vaginal wall or prostate and then continuous cephalad in front or behind Denonvillier’s fascia pending anterior location of the tumour. The specimen is extracted trough the perineal wound. The perineal defect is then closed primarily, with a subcutaneous gluteal turnover flap [33] or by aid of (biological) mesh upon individual basis.

The primary endpoint was feasibility of the technique in terms of intraoperative complications.[34]. Secondary endpoints included 30-day major morbidity (Clavien Dindo ≥ 3), perineal wound healing, and histopathological outcomes. CRM + was defined as presence of tumour cells ≤ 1 mm of the surgical plane. The specimen quality was graded according to Quirke [2]. Perforation was defined as a tear or hole from the surface of the surgical specimen (mesorectum or at the level of the sphincters) into the rectal lumen.

All data are presented as N (%) for binary data and for continuous outcome as mean ± SD and median range as well since normal distribution is not expected in this small cohort. To explore the potential impact for the extent of the procedure, which increases from APE via an unilateral ELAPE to a bilateral ELAPE, a comparative analysis for these procedures was performed. For the comparative analysis, a Fisher’s exact test was used for categorical variables and the non-parametric Mann–Whitney U test or Kruskal–Wallis test for continuous variables. A p value < 0.05 was considered statistically significant. Statistical analysis was performed using SPSS version 24 for Windows (SPSS, Chicago, IL, USA).

A total of 32 patients were included (24 males, mean age 65.7 [± 12.8]) from 5 different expert colorectal cancer centers with a case load varying between 1 and 12 procedures. The first procedure in this series was performed in June 2014 and the last in July 2018. Seventeen patients had cT3 stage rectal cancer and seven were cT4 stage (Table 1). Nodal involvement was diagnosed in 14 patients (44%). In one patient, a suspected para-aortic lymph node metastasis was present and, therefore, categorized as distant (M +) disease. No other peritoneal, liver or lung metastasis were encountered in the preoperative work-up. The majority of cases was found to have a threatened margin to the mesorectal fascia (MRF) (n = 12, 66%) on baseline magnetic resonance imaging (MRI) and the tumour was located at or below the level of the anorectal junction in 22 cases (69%). Extension of low tumours into the sphincter complex was seen in ten patients, ingrowth into the levator ani muscles and anterior involvement (prostate or vagina) was encountered in four and two cases, respectively. A substantial part of the patients received neoadjuvant chemoradiotherapy (n = 20, 63%).

A bilateral extralevatory APE was performed in 17 cases (53%), a unilateral ELAPE in 7 cases (22%), and an APE without resection of the levator ani muscle in 8 patients(25%) (Table 2). A beyond TME resection (n = 8, 25%) was performed for tumours that invaded other organs or those at risk of CRM +, and consisted of additional (partial) resection of the prostate (n = 5), vagina (n = 1), seminal vesicles (n = 1), and ovaries (n = 1). An omentoplasty was performed in six patients (19%), all without use of indocyanine green, to assess the perfusion of the mobilized greater omentum. The perineal defect was predominantly closed by primary closure (n = 18, 56%), and in the other 15 cases, either a musculocutaneous gluteal flap (n = 6, 19%), an absorbable mesh (n = 7, 22%) or a non-absorbable mesh (n = 1, 3%) was used for perineal reconstruction.

Intraoperative complications occurred in five patients (16%) and consisted of one carbon dioxide embolus, one urethral injury, one pelvic sidewall injury and two intraoperative rectal perforations. No conversions to laparotomy were reported and conversion to an open perineal approach was necessary once, due to the inability to progress with the dissection, despite abdominal assistance in a two-team approach (Table 2).

There was no 30-day mortality. Major 30-day postoperative morbidity was reported in three patients (9%). This consisted of a compartment syndrome of the lower leg requiring fasciotomy, a deep pelvic abscess due to omental infarction with return to theatre and a urinoma following urethral injury which was managed with percutaneous drainage (Table 3). Perineal wound healing was impaired in 47% (n = 15) of patients in this cohort; one flap failure (3%), four break through abscesses (deep perineal infection) (13%), and ten superficial skin infections (31%). One superficial dehiscence and one flap failure were treated by negative pressure therapy, three breakthrough abscesses needed packing, and one abscess required drainage followed by secondary healing. One patient with a superficial skin infection that was initially not severe developed a late perineal hernia with wound dehiscence requiring secondary reconstruction. The median time to perineal wound healing was 14 days for those without perineal infection and 45 days in complicated perineal recovery (p = 0.002).

CRM + (R1) upon pathological evaluation was seen in four cases (13%) and intraoperative specimen perforation occurred in two procedures (6%). The positive margin was anterior in three out of the four R1 resections. A complete or nearly complete specimen was obtained in the vast majority of cases (n = 28, 90%) (Table 4).

Comparative analysis based on the extent of the procedure (conventional APE, uni- or bilateral ELAPE) revealed that intraoperative complications were higher in the ELAPE groups (Table 5). There were three severe complications in the unilateral ELAPE (pelvic sidewall injury, urethral injury, and rectal tube perforation), two in the bilateral ELAPE (CO₂ embolus and rectal tube perforation), and no intraoperative complications in the APE group (p 0.071). Severe postoperative complications were distributed equally among the three procedures. A composite of optimal pathology, defined as circumferential and distal resection margin-without perforation and a complete/near complete specimen, was achieved in 84.4% cases in this series. An unsuccessful resection was seen in two out of seven (29%) unilateral ELAPE procedures which was higher than in conventional APE (13%) and bilateral ELAPE (16%) but did not reach statistical significance.