Functional Outcomes after Transanal Surgery

Abstract

Transanal surgery has gained in popularity during the latter part of the last decade for both rectal cancer and benign disease. The current role for local excision of early rectal neoplastic lesions has expanded due to better understanding of risk factors for lymph node metastasis and heightened awareness for the long-term sequelae of radical surgery. Transanal resection of the rectum (both for cancer or inflammatory bowel diseases) has now been established as a successful procedure that overcomes some of the limitations of the abdominal approaches. Once the feasibility, safety, and the oncologic results of transanal minimally invasive approaches for patients with rectal cancer have been acknowledged, quality of life and functional outcomes have become increasingly important issues. This article provides an overview of the different techniques currently available for the minimally invasive transanal treatment of rectal lesions, particularly focusing on functional outcomes.

Transanal surgery has become more widespread during the last decade, both for rectal cancer and benign disease.

The surgical management of rectal lesions has evolved dramatically during the past 40 years. The introduction of new dissection techniques, such as total mesorectal excision (TME), the availability of more reliable surgical devices (i.e., mechanical staplers, ultrasonic dissectors, etc.), and the advances in neoadjuvant treatment protocols, allowed the transition from mutilating procedures such as abdominoperineal resections (APR) to sphincter-saving procedures with safe oncological outcomes. At the same time, the introduction of laparoscopy and the advent of robotic surgery have contributed to faster postoperative recoveries and better functional outcomes compared with open surgery. ¹ However, techniques such as TME can be extremely difficult to perform with laparoscopy and can result in mortality rates as high as 2 to 3%, ² in notable postoperative morbidity, with leak rates of up to 12 to 16% ² and poor functional outcomes due to injury of autonomic pelvic nerves to the bladder and sexual organs that lead to urinary incontinence and sexual dysfunction in up to 30 to 35% of patients. ³ Moreover, bowel dysfunction and fecal incontinence of various severity can occur in more than 60% of the patients. ² To overcome such limitations, transanal minimally invasive approaches have been developed over the years, including transanal endoscopic surgery (TES) and transanal total mesorectal excision (TaTME). Despite the improvements of medical therapy for ulcerative colitis, a proctocolectomy is required in up to 15% of patients. Conventionally, rectal dissection and the creation of a double-stapled ileal pouch anal anastomosis (IPAA) was performed transabdominally by an open or laparoscopic approach. However, this can be technically challenging due to the restricted space in the pelvis and technical difficulties with cross stapling of the distal rectum. The transanal approach has gained more and more interest, even for the approach of benign diseases (i.e., inflammatory bowel diseases [IBDs]), overcoming the most cumbersome phases of a proctectomy via an abdominal approach. Once that feasibility, safety, as well as the oncologic results of transanal minimally invasive approaches has been acknowledged, quality of life (QoL) and functional outcomes have become increasingly important issues. This article provides an overview of the different techniques currently available for the minimally invasive transanal treatments of rectal cancer and IBD, particularly focusing on functional outcomes.

Anorectal Function

Anorectal function is the complex series of physiological mechanisms that regulate gas and stool continence and defecation frequency. Preoperative assessment of baseline anorectal function is fundamental to estimate postoperative outcomes after local excision (LE) and are key for a transparent obtainment of the informed consent. Other factors are as well responsible for postoperative functional outcomes and include tumor characteristics, the extent of resection, and surgical technique. Different questionnaires have been developed over time to assess functional outcomes, including the presence of fecal incontinence and its impact on QoL. Among the most widely adopted are the Jorge–Wexner Continence Scale, ⁴ the Fecal Incontinence Severity Index, ⁵ and the Rockwood Fecal Incontinence Quality of Life. ⁶ A thorough physical examination with digital rectal examination must be performed for the evaluation of the anal canal resting tone and squeeze. In case a sphincter deficit is suspected, an evaluation of the anatomical site, size, and integrity of the sphincter should be evaluated with the aid of magnetic resonance imaging or endoanal ultrasonography. Baseline functional data regarding rectal wall compliance, rectal perception, anal resting, and squeeze pressure should be obtained through anorectal manometry examination.

Local Excision

LE includes a series of surgical techniques for the treatment of low rectal lesions with minimal impact on patients that involves full-thickness resection of the tumor and a margin of rectum, down to the perirectal fat, but not necessarily including any draining lymphatics. ⁷ Transanal excision (TAE) was the first LE technique performed, with the resection of a prolapsing rectal tumor in the 19th century by Lisfranc. However, TAE was not diffused until the development of self-retaining rectal retractors by Parks in the 1960s that allowed better elevation and dissection in the submucosal plane as well as an easier closure of the rectal defect. The current role of TAE in the treatment of rectal lesions is mostly limited to benign lesions and T1N0 rectal cancers with low-risk pathologic features (e.g., moderate to well-differentiated tumor, absence of lymph vascular invasion, and absence of perineural invasion). Other indications include excisional biopsy of large rectal lesions at high risk for malignancy, radicalization of previous polypectomy bed due to histologic cancer diagnosis, and palliative treatment in case of significant comorbidities or incurable systemic disease. Recently, in the trial setting, LE has been offered in cases of complete tumor response (CTR) or near-CTR after neoadjuvant therapy for patients with locally advanced rectal cancer (T3–T4 and/or N + ). In the latter case, LE was compared with TME; however, it failed to provide an advantage for LE due to the high rate of salvage TME, leading to a very high morbidity and definitive colostomy rates. Another problem with LE after neoadjuvant treatment is the high rate of patient refusal of salvage TME, thus the high rate of follow-up losses. ⁸ From a functional perspective, TAE has a low impact on the sphincter mechanism and, especially in cases of voluminous rectal lesions, may even ameliorate continence, as those are often responsible for outlet dysfunction and mucous discharge. However, the use of an anoscope and different types of retractors may expose the patient to postoperative reduction in internal anal sphincter resting pressure in up to 23% of cases, ⁹ and manual anal dilation has been also associated with loss of continence in more than 25% of cases due to the stretch of the internal anal sphincter fibers. ¹⁰

Transanal Endoscopic Surgery

The limited visibility achievable during TAE relegates the use of the technique only to the distal third of the rectum. In 1983, the concept of TAE was associated with that of minimally invasive surgery with the introduction of transanal endoscopic microsurgery (TEM) which is composed of:

• An operating proctoscope

• A working adapter and a working insert to connect the proctoscope to surgical instruments, camera, and insufflator

• A metal arm to fix the proctoscope to the operating table

• A light source and a telescope

• Surgical tools (e.g., graspers, scissors, electrocautery, needle holder, etc.). ¹¹

This solution provided capability to operate on larger and more proximal lesions, up to 20 cm from the anal verge. From the original design by Buess, other platforms have been developed with similar concepts of operation, such as transanal endoscopic operation (TEO) by Karl Storz. TEO instrumentation includes a 7- or 15-cm proctoscope (4 cm in diameter) with three working channels (12, 5, and 5 mm) for dedicated or conventional laparoscopic instruments, and a 5-mm channel for a 30-degree two-dimensional camera. The shape of the TEO proctoscope tip allows manipulation and suturing of the rectal wall on a 360-degree surface. A standard laparoscopic unit is used in combination with this system, with the imaging being displayed on a screen. ¹¹ Recently, with the advances in laparoscopic instruments, the single-port platform became usable with standard laparoscopic equipment and applied for the transanal minimally invasive surgery (TAMIS) since 2009. TAMIS proved to be a less expensive, yet effective platform compared with the previous TEM and TEO that require expensive dedicated equipment, longer setups, and complex specialized training. There are several intraoperative factors during TES that may directly affect bowel function after surgery, including the length of surgery, size, and location of the lesion. According to a recent systematic review including almost 1,300 patients, most studies reported a certain degree of deterioration in manometric scores after both TEM and TAMIS, and some reported a transitory worsening in defecatory function, including loss of continence in some cases. A possible explanation is that full-thickness excision is responsible for postoperative inflammation and subsequent fibrosis. However, QoL does not seem to be significantly affected after TES. ¹² A word of caution on the analysis of such information comes from the wide variability in functional outcomes reporting among the different studies. Only one study by Goldenshluger et al investigated long-term functional outcomes after TAMIS, and included 23 patients with a median follow-up of 5 years. ¹³ Most of the patients reported good postoperative control on flatus (69.57%) and stool (82.61%). Only 26% of the patients reported a need to evacuate within 1 hour after the previous and 35% reported periodic urge to pass stools. None of the patients reported constipation. The total low anterior resection syndrome (LARS) score revealed that 17 (73.91%) of the patients had no definitive LARS following surgery, 4 (17.39%) reported mild LARS, while 2 (8.69%) had major LARS. ¹³

Transanal Total Mesorectal Excision

The concept of TaTME has been proposed to overcome the technical challenges of the transabdominal approaches (open, laparoscopic, and robotic) in the most difficult cases such as obese, male patients with mid-low rectal cancers. There are concerns that such patients with a narrow, radiated pelvis and bulky mesorectum may currently be undergoing sphincter-sparing resections with an involved circumferential resection margin (CRM), a poor-quality TME, or even an unnecessary APR. It has been recently claimed that TaTME may offer the following advantages:

1. A longer distal resection margin, thanks to the direct visual control during distal transection, avoids the risk of inadequate clearance in cancer surgery and of excessively long rectal cuff in case of procedures for IBDs, that could lead respectively to worse oncological and functional outcomes.

2. A decreased rate of positive CRM.

3. Better TME quality. ¹⁴

4. Rectal transection performed under visual control prevents multiple stapling and dog ears and, combined with a single-stapled anastomosis, can potentially lower the risk of leak, although the comparative benefits of single-stapled over conventional double-stapled anastomosis are still unproven. ¹⁵

5. An enhanced visualization and exposure of the TME dissection planes, especially in the deep pelvis, theoretically allowing for improved functional outcomes over the abdominal approaches. In fact, avoiding injury to the pelvic hypogastric or sacral splanchnic nerves should lower the urinary and sexual dysfunction reported after minimally invasive (laparoscopic/robotic) or open TME (0–26 and 11–38%, respectively). ^{16 17 18 19}

At the same time, there is concern that the functional data might actually be compromised through the TaTME approach, especially during the early stages of the learning curve. In fact, as suggested by the high rate of handsewn anastomoses early on in the TaTME experience, there seems to be a tendency toward a lower anastomotic height, even for mid-rectal tumors. ^{20 21} However, technique standardization and advanced training lead to an increased rate of stapled anastomoses. ^{15 22 23 24} Moreover, there is a risk of “reversed coning” early in the learning curve, with dissection into the pelvic sidewall leading to neurovascular injuries. Approaching the anatomy from a new bottom-up perspective, in combination with anatomic distortion through CO ₂ insufflation, can easily lead to misperception of planes, resulting in operating in the wrong planes. There is concern regarding sphincter injury through the insertion of the transanal platform. Also, the time the anal canal is subject to the dilation due to the operating platform can be lengthy. Given these potential negative impacts on function, there is currently a lot of interest on functional outcomes data, although scientific evidence on the topic is still scarce.

The first functional data for transanal endoscopic proctectomies was reported by Rouanet et al ²⁵ in 2013. Thirty male patients undergoing intersphincteric resection (ISR) for mid-to-low rectal cancer were followed up for 12 months after stoma closure. Of those, 87% received neoadjuvant radiotherapy. Full continence was observed in 40% of patients, 15% reported incontinence to liquids, 35% to gas, and 25% complained of stool fragmentation. The mean Cleveland Clinic Florida-Fecal Incontinence Score (CCF-FIS) for this group of patients was 11 (range: 0–20). These results did not differ from a report coming from the same unit on the functional outcomes observed after ISR and coloanal anastomosis performed via abdominal approach. ²⁶ Tuech et al ²⁷ analyzed a larger group ( n  = 56) of consecutive patients with low rectal cancer. Male gender (73.2%) and patients requiring neoadjuvant radiochemotherapy (84%) were prevalent. Ten patients had a partial ISR and one a complete ISR. Fifty-two patients underwent a restorative procedure: 46 handsewn coloanal anastomoses and 6 delayed coloanal anastomoses. The overall median CCF-FIS at 12 months follow-up was 5 (range: 3–18). Three patients required a tertiary stoma for severe fecal incontinence after ISR (CCF-FIS 15, 17, and 18). Fragmentation was reported by 28% of patients. Urinary retention occurred in five patients requiring temporary catheterization; at 3 months, all patients reported normal urinary function. Male sexual function could only be evaluated in 18 patients who were still sexually active: 4 reported a decrease in ejaculatory amount, 2 reported failure to ejaculate, and 4 reported a decreased potency. The randomized controlled trial by Pontallier et al ²⁸ reported on functional outcomes between transanal and laparoscopic ISRs with sphincter preservation for low rectal cancer at a median follow-up of 38 months. Bowel and urinary function were similar between the two groups. Major LARS was reported in 82% of transanal and 76% of laparoscopic procedures. However, the authors observed a marked impaired sexual function (including sexual activity, erectile and ejaculatory functions) after complete laparoscopic dissection. Among these sexually active patients, the only independent risk factor for loss of sexual activity after multivariate analysis was the laparoscopic approach to the low rectum. Although the study cohort includes more transabdominal approaches than transanal, it still provides a valid representation on the potential benefits on the preservation of sexual function achievable via transanal assistance for the distal one-third of the dissection. Recently, Koedam et al ²⁹ analyzed QoL and functional outcomes of 30 patients undergoing restorative TaTME for rectal cancer. Validated questionnaires were administered at baseline (preoperatively) and at 1 and 6 months after surgery, with a 100% response rate at stoma closure and 93% at 6 months. Concerning QoL in general, the preoperative mean score of the EuroQol with five-dimension three-level (EQ-5D-3L) index was 90.2. This score significantly decreased to 78.2 ( p  = 0.031) at 1 month, but returned close to the preoperative value (86.0) at 6 months. The EuroQol visual analog scale showed a similar trend. Colorectal cancer-specific QoL scores revealed a drop in scores at 1 month after surgery for QoL ( p  = 0.012), physical functioning ( p  = 0.001), role functioning ( p  < 0.001), fatigue ( p  = 0.002), and general pain ( p  = 0.001). After 6 months, the effect of TaTME disappeared for these scores, except for social functioning ( p  = 0.013) and anal pain ( p  = 0.013) which remained significantly lower than preoperative scores. No difference was observed in bladder function at 1 and 6 months after surgery, compared with preoperative function. Six months after stoma closure, major LARS was still present in 33% of patients. The mean preoperative LARS score was 15.4 compared with a postoperative score of 35.7 ( p  = 0.001) and 21.7 ( p  = 0.339) at 1 and 6 months, respectively. A total of 46.7% of patients reported no LARS at 6 months. Decreased sexual interest was observed at 1 month but returned to nearly preoperative values at 6 months. No significant erectile malfunction was seen compared with baseline. Veltcamp Helbach et al ³⁰ used similar validated questionnaires to compare the QoL and functional outcomes between 27 consecutive patients undergoing TaTME and 27 patients undergoing laparoscopic TME (LapTME). All TaTMEs were performed by one surgeon at the first experience with the technique. The two groups were comparable except for age (68 vs. 62.7 years) and length of follow-up (20 vs. 59.5 months). No differences in each of the five domains of the EQ-5D for assessing QoL were reported: the overall health status was 75.6 and 79.1 for TaTME and LapTME, respectively. Although patients in both groups reported LARS, no significant difference in the severity was identified between the two groups (16 in TaTME vs. 8 in LapTME; p  = 0.087). Furthermore, the mean LARS questionnaire scores were equivalent between the two groups (27.7 and 24.0 in TaTME and LapTME, respectively; p  = 0.131). When comparing the questionnaire items individually, including incontinence to flatus and liquid stool, no significant difference was observed between the groups. However, the follow-up period was short for TaTME, and 23/27 anastomoses in the TaTME group were end-to-end, while all anastomoses in the laparoscopic group were performed in a side-to-end fashion. No differences were reported in urinary function. All items evaluated by the European Organization for Research and Treatment of Cancer QLQ-CR29 (Quality of Life Questionnaire for Colorectal Cancer), including sexual outcomes, were similar between the two groups, exception made for a worse fecal incontinence score in the TaTME group. Bjoern et al ³¹ compared QoL and functional outcomes between 49 TaTMEs and 36 LaTMEs operated over a period of 7 years at a single institution. Anorectal symptoms were significantly worse in TaTME including buttock pain ( p  = 0.011), diarrhea ( p  = 0.009), clustering of stools ( p  = 0.017), and urgency ( p  = 0.032). However, total LARS score was comparable ( p  = 0.054). Sexual results were comparable while an overall higher satisfaction with urinary function was observed in the TaTME group ( p  = 0.01); no differences in International Prostate Symptom Score status were found ( p  = 0.23). Recently, the same group ³² aimed to assess anal function through manometry and the LARS score in a group of 36 TaTMEs performed for mid-low rectal cancer and compared the results to those of 12 LapTMEs. The mean follow-up time from the index operation to the assessment date was 41.34 months (±24.83). The mean resting pressure did not differ significantly between the groups (36.44 mm Hg ± 18.51 and 36.58 mm Hg ± 13.31 in the TaTME and LapTME groups, respectively; p  = 0.98). The mean squeeze pressure was also comparable (125.00 mm Hg ± 66.14 and 111.83 mm Hg ± 51.11 in the TaTME and LapTME groups, respectively; p  = 0.53). The mean total LARS score was comparable (29.5 ± 8.21 vs. 28.08 ± 9.61 for TaTME vs. LapTME; p  = 0.62) and showed comparable single parameters. The analysis of correlation between LARS score and manometry parameters showed no significant association between resting or squeeze pressure and LARS score. Rubinkiewicz et al ³³ compared functional outcomes between 23 TaTMEs and 23 LapTMEs performed for low rectal cancer. Twenty (87%) from TaTME and 21 (91%) from LapTME groups developed LARS postoperatively. There were no significant differences between the groups in terms of LARS occurrence ( p  = 0.63) and severity. The median Wexner score was comparable in the two groups ( p  = 0.83). Univariate analysis identified postoperative complications as a risk factor for LARS development in both groups ( p  = 0.02). Recently, Keller et al ³⁴ reported functional outcomes and QoL on 61 patients undergoing TaTME for rectal cancer. At a follow-up performed between 12 and 24 months from the operation, general QoL (measured by the EQ-5D and QLQ-C30) scores were improved, as well as urinary and emotional function, with stable outcomes in all other symptoms, fecal incontinence, major LARS, and sexual function. Interestingly, the regression analysis showed that erectile, urinary, bowel functional outcomes, and global QoL were not affected by neoadjuvant treatments, tumor or anastomotic height, anastomotic leak, or body mass index. Patients younger than 50 years had better urinary outcomes ( p  = 0.017). The total operating time had no impact on functional outcomes or QoL, but longer perineal operating times were associated with worse LARS ( p  = 0.001). Urinary and bowel functional outcomes did not influence overall QoL, and similarly, there was no relationship between erectile and urinary functional outcomes. However, erectile function significantly affected QoL after more than 1 year ( p  = 0.044) with a direct relationship between better sexual function and better QoL. Results of the aforementioned studies are summarized in Tables 1 and 2 .

Table 1. Studies overview.

Reference	Year	Country	Study design	Restorative procedures	Intervention	Anastomosis	Distance from anal verge (cm)	Neoadjuvant treatment	Follow-up after stoma closure (mo)
Rouanet et al 25	2013	France	Case series	30	ISR	CAA IPAA	0–5 cm: 66.6% 5–10 cm: 33.4%	87%	12
Rouanet et al 26	2002	France	Case series	30	ISR: 13	CAA: 11 (26%) IPAA: 15 (35%)	2 a (0–3)	100%	76 a
Tuech et al 27	2015	France	Case series	52	ETAP (11 ISR)	HS-CAA: 46 Delayed HS-CAA: 6	4 a (0–5)	84%	12
Pontallier et al 28	2016	France	RCT	72	38 TA 34 LAP	Park's coloanal (18 TA; 11 LAP) ISR (20 TA; 23 LAP)	4 a (2–6)	79% TA 88% LAP	38 a (13–59)
Koedam et al 29	2017	The Netherlands	Case series	30	TaTME	57% single stapled (SS) 43% HS-CAA	6 a (4–8)	73%	11 a (IQR 5–16)
Veltcamp Helbach et al 30	2019	The Netherlands	Comparative	54	27 TaTME 27 LAP	100% single stapled (SS)	TaTME: 0–5 cm 33.3%; 6–10 cm 51.8% LAP: 0–5 cm 25.9%; 6–10 cm 66.6%	66.6% TaTME 81.4% LAP	20 (6.6–44.4) TaTME 59.5 (39.7–82) LAP ( p  = 0.000)
Bjoern et al 31	2019	Denmark	Comparative	88	49 TaTME 36 LAP	100% single stapled (SS) 23/27 TaTME EE; 2/27 SE LAP:SE	8.35 ± 1.72 TaTME 8.14 ± 1.88 LAP	16.3% TaTME 22.2% LAP	22.69 ± 10.30 TaTME 75.08 ± 17.60 LAP ( p  < 0.001)
Bjoern and Perdawood 32	2020	Denmark	Comparative	48	36 TaTME 12 LAP		8.11 ± 1.58 TaTME 7.75 ± 1.76 LAP	19.4% TaTME 25% LAP	23.80 ± 9.51 TaTME 70.58 ± 9.49 LAP ( p  < 0.001)
Rubinkiewicz et al 33	2019	Poland	Comparative	41	23 TaTME 23 LAP	TaTME/LAP: 21 stapled, 2 HS-CAA	3 a (2–4) TaTME 4 a (3–5) LAP	78.2% TaTME 82.6% LAP	6
Keller et al 34	2019	Multicentric	Case series	61	TaTME	not specified	6.18 ± 2.05	44%	12

Abbreviations: CAA, coloanal; EE, end-to-end; ETAP, endoscopic transanal proctectomy; HS-CAA, handsewn coloanal; IPAA, ileal pouch anal anastomosis; ISR, intersphincteric resection; KG, Knight–Griffen; LAP, laparoscopic; RCT, randomized controlled trial; SE, side-to-end; TA, transanal.

^aMedian value.

Table 2. Functional results.

Reference	Incontinence	Anorectal function	Mean CCF–FIS	Wexner score	LARS	IPSS	Urinary function	Sexual function	EQ-5D-3L	EORTC QLQ-CR29 + QLQ-C30
Rouanet et al 25	35%: gas 15%: liquids	Stool fragmentation 25%	11 (0–20)
Rouanet et al 26	12%: gas 19%: frequent major soiling 37%: occasional minor leak 12%: nocturnal 37% urgency	Stool fragmentation 33%
Tuech et al 27	3 severe	Stool fragmentation 28%	5 (3–18) a	4 a (3–12) b Score > 7: 28.5%			9.6% urinary retention	4/18: decreased ejaculatory amount 2/18: failure to ejaculate 4/18 decreased potency
Pontallier et al 28				9 a (2–20) TA 10 a (3–20) LAP Score > 10: 42% TA vs. 41% LAP	36 a (12–42) TA 37 a (12–42) LAP Major LARS: 82% TA vs. 76% LAP	5.5 a (0–23) TA 3.5 a (0–27) LAP		IIEF 17 TA vs. 7 LAP FSFI ≤ 19: 66.7% TA vs. 40% LAP
Koedam et al 29					Preop: 15.4 1 mo: 35.7 ( p  = 0.001) 6 mo: 21.7 ( p  = 0.339) Major LARS at 6 mo: 33%		Incontinence, increased frequency, dysuria not significantly changed (mean difference between preop, 1 and 6 mo < 5)	Male interest in sexual intercourse significantly decreased at 1 mo, but returned to the same level at 6 mo No significant increase in erection problems	Preop: 90.2 (83.9–96.5) 1 mo: 78.2 (68.9–87.4) ( p  = 0.031) c 6 mo: 86 (79.9–92.2)	Drop at 1 mo: QoL ( p  = 0.012) Physical functioning ( p  = 0.001) Role functioning ( p  < 0.001) Fatigue ( p  = 0.002) General pain ( p  = 0.001) After 6 mo: Social functioning ( p  = 0.013) Anal pain ( p  = 0.013)
Veltcamp Helbach et al 30	EORTC QLQ-C29 33.3 TaTME vs. 16.7 LAP				TaTME 27.7 (22.3–32.8) LAP 24 (19.9–28.2) Major LARS 59.2% TaTME vs 29.6% LAP	TaTME: 8 (4.2–11.8) LAP: 6.7 (3.6–9.9)	EORTC QLQ-C29 incontinence 7.4 TaTME vs. 9.9 LAP	EORTC QLQ-CR29 impotence score (men): 41 TaTME vs. 51 LAP EORTC QLQ-CR29 dyspareunia score (women): 7.4 TaTME vs 8.3 LAP	Index: TaTME 88.1 (83–1-93.1) LAP 92.8 (88.2–97.4) VAS: 75.6 (69.9–81.3) TaTME vs. 79.2 (72.8–85.3)	Fecal incontinence: 33.3 TaTME vs. 16.7 LAP ( p  = 0.032) Hair loss: 9.9 TaTME vs. 0 LAP ( p  = 0.01)
Bjoern et al 31	EORTC QLQ-C29 20.4 TaTME vs. 13.88 LAP	EORTC QLQ-C29: Stool frequency 19.79 TaTME vs. 17.12 LAP Diarrhea: 17.68 TaTME vs. 4.62 LAP ( p  = 0.009) LARS: Clustering of stools ≥ 1/wk: 21% TaTME vs. 41.6% LAP ( p  = 0.017) Urgency ≥ 1/wk: 32.6% TaTME vs. 41.6% LAP ( p  = 0.032)			26.18 ± 10.32 TaTME vs. 20.61 ± 14.51 LAP Major LARS 34.6% TaTME vs. 33.3% LAP	6.73 ± 7.41 TaTME vs. 10.05 ± 8.15 LAP	EORTC QLQ-C29 incontinence 2.04 TaTME vs. 3.7 LAP EORTC QLQ-CR29 dysuria 2.04 TaTME vs. 1.85 LAP	EORTC QLQ-C29 impotence score (men) 50.54 TaTME vs. 48.33 LAP EORTC QLQ-CR29 dyspareunia score (women): 0 TaTME vs. 2.08 LAP		77.72 TaTME vs. 79.86 LAP Buttock pain: 14.28 TaTME vs. 2.77 (LAP ( p  = 0.011) Diarrhea: 17.68 TaTME vs. 4.62 LAP ( p  = 0.009)
Bjoern and Perdawood 32		Mean resting pressure: 34.44 ± 18.51 mm Hg TaTME; 36.58 ± 13.31 mm Hg LAP Mean squeeze pressure (mmHg): 125 ± 66.1 TaTME; 111.83 ± 51.11			29.5 ± 8.21 TaTME; 28.08 ± 9.61 LAP Major: 55.5% TaTME vs. 58.3% LAP
Rubinkiewicz et al 33				Preop a : 0 (0–2) TaTME; 0 (0–1) LAP Postop a : 8 (4–12) TaTME; 7 (3–11) LAP	Preop a : 5 (0–21) TaTME; 0 (0–5) LAP Postop a : 29 (24–34) TaTME; 30 (21–34) Major: 35% TaTME; 52% LAP
Keller et al 34		Less defecation problems ( p  = 0.042)			Preop: 35% minor, 24% major Postop: 60% stable or improved; 40% worse than preop Long perineal operating time associated with worse LARS		Improved micturition ( p  < 0.001) Better urinary outcomes in patients < 50 y	Not changed at follow-up	All dimensions unchanged at follow-up	All dimensions unchanged at follow-up except for: Increased “emotional function” ( p  = 0.003) Decreased anxiety ( p  < 0.001) Decreased body image issues and abdominal pain Direct relationship between sexual function and QoL

Abbreviations: CCF-FIS, Cleveland Clinic Florida-Fecal Incontinence Score; EORTC, European Organization for Research and Treatment of Cancer; EQ-5D-3L, EuroQol with 5-dimension 3-level; FSFI, Female Sexual Function Index; IIEF, Index of Erectile Function Questionnaire; IPSS, International Prostate Symptom Score; IQR, interquartile range; LARS, low anterior resection syndrome; Postop, postoperative; Preop, preoperative; QoL, quality of life; TaTME, transanal total mesorectal excision.

Note: p is reported only if significant.

^aMedian.

^bExcluded the three patients with severe incontinence (Wexner scores 15, 17, and 18).

^cSignificant increase in problems experienced in social life and pain at 1 month, but no more at 6 months.

Regarding IBD surgery, the only report available in the literature is a multicentric study by Chandrasinghe et al ³⁵ comparing functional outcomes after transanal IPAA (Ta-IPAA) and abdominal IPAA (Abd-IPAA) at a follow-up of 12 months. A total of 374 patients (100 Ta-IPAAs and 274 Abd-IPAAs) were included. Overall QoL (Cleveland Global Quality of Life) scores were comparable in the two groups (0.75 ± 0.11 vs. 0.71 ± 0.14, respectively, p  = 0.1). QoL (7.71 ± 1.17 vs. 7.30 ± 1.46; p  = 0.04) and energy level items (7.16 ± 1.52 vs. 6.66 ± 1.68; p  = 0.03) were significantly better after Ta-IPAA, while the quality of health item was comparable (7.68 ± 1.26 vs. 7.64 ± 1.44; p  = 0.96). Stool frequencies (>10/24 hours: 22 vs. 21%; p  = 1.0) and the rate of single episode of major incontinence during the 12-month period (27 vs. 26%; p  = 0.89) were similar. The subanalysis comparing patients undergoing TME and a close rectal dissection (CRD) did not show significant difference on the analyzed variables, exception made for a higher stool frequency rate (>10/24 hours) in the CRD group. Results did not change after excluding patients undergoing an anastomotic leak.

Conclusion

Transanal surgery has become more widespread during the last decade for both rectal cancer and benign disease. Notwithstanding, the scarcity of the literature on the topic and the wide variability in the reporting of functional outcomes among the studies, functional results after transanal minimally invasive LE (TAMIS, TEO, and TEM) seem favorable.

At the same time, TaTME seems to offer at least equivalent functional outcomes and QoL when compared with laparoscopic/robotic TME.

In a QoL operation such as IPAA, the functional outcomes are of paramount importance. However, as the application of this technique in IBD surgery was limited to enthusiasts, robust long-term functional and outcome data are very limited.

Overall, we can conclude that data on transanal minimally invasive approaches are still lacking and more evidence is eagerly awaited.