Functional Outcomes After Transanal Total Mesorectal Excision (taTME) for Rectal Cancer: Results from the Phase II North American Multicenter Prospective Observational Trial.

OBJECTIVE: To investigate fecal incontinence and defecatory, urinary, and sexual functional outcomes after taTME. SUMMARY BACKGROUND DATA: Proctectomy for rectal cancer may result in alterations in defecatory, urinary, and sexual function that persist beyond 12 months. The recent multicenter Phase II taTME trial demonstrated the safety of taTME in patients with stage I-III tumors. METHODS: Prospectively registered self-reported questionnaires were collected from 100 taTME patients. Fecal continence (FIQL, Wexner), defecatory function (COREFO), urinary function (IPSS), and sexual function (FSFI-female, IIEF-male) were assessed preoperatively (PQ), 3-4 months post-ileostomy closure (FQ1), and 12-18 months post-taTME (FQ2). RESULTS: Among 83 patients who responded at all three time points, FIQL, Wexner, and COREFO significantly worsened post-ileostomy closure. Between FQ1 and FQ2, FIQL lifestyle and coping, Wexner, and COREFO incontinence, social impact, frequency, and need for medication significantly improved, while FIQL depression and embarrassment did not change. IPSS did not change relative to preoperative scores. For females, FSFI declined for desire, orgasm, and satisfaction between PQ and FQ1, and did not improve between FQ1 and FQ2. In males, IIEF declined with no change between FQ1 and FQ2. CONCLUSIONS: Although taTME resulted in initial decline in defecatory function and fecal continence, most functional domains improved by 12 months after ileostomy closure, without returning to preoperative status. Urinary function was preserved while sexual function declined without improvement by 18 months post-taTME. Our results address patient expectations and inform shared decision-making regarding taTME.

Combined Robotic Ventral Mesh Rectopexy and Sacrocolpopexy for Multicompartmental Pelvic Organ Prolapse.

BACKGROUND: Multispecialty management should be the preferred approach for the treatment of pelvic floor dysfunction because there is often multicompartmental prolapse. OBJECTIVE: To assess the safety of combined robotic ventral mesh rectopexy and either uterine or vaginal fixation for the treatment of multicompartmental pelvic organ prolapse at our institution. DESIGN: Retrospective analysis. SETTINGS: Tertiary referral academic center. PATIENTS: All patients who underwent a robotic approach and combined procedure and whose cases were discussed at a biweekly pelvic floor multidisciplinary team meeting. MAIN OUTCOME MEASURES: Operative time, intraoperative blood loss and complications, postoperative pelvic organ prolapse quantification score, length of stay, 30-day morbidity, and readmission. RESULTS: From 2018 to 2021, there were 321 operations for patients with multicompartmental prolapse. The mean age was 63.4 years. The predominant pelvic floor dysfunction was rectal prolapse in 170 cases (60%). Pelvic organ prolapse quantification scores were II in 146 patients (53%), III in 121 patients (44%), and IV in 9 patients (3%); 315 of 323 cases included robotic ventral mesh rectopexy (98%). Sacrocolpopexy or sacrohysteropexy was performed in 281 patients (89%). Other procedures included 175 hysterectomies (54%), 104 oophorectomies (32%), 151 sling procedures (47%), 149 posterior repairs (46%), and 138 cystocele repairs (43%). The operative time for ventral mesh rectopexy was 211 minutes and for combined pelvic floor reconstruction was 266 minutes. Average length of stay was 1.6 days. Eight patients were readmitted within 30 days: 1 with a severe headache and 7 with postoperative complications (2.5%), such as pelvic collection and perirectal collection, both requiring radiologic drainage. Four complications required reoperation: epidural abscess, small-bowel obstruction, missed enterotomy requiring resection, and urinary retention requiring sling revision. There were no mortalities. LIMITATIONS: Retrospective single-center study. CONCLUSIONS: A combined robotic approach for multicompartmental pelvic organ prolapse is a safe and viable procedure with a relatively low rate of morbidity and no mortality. This is the highest volume series of combined robotic pelvic floor reconstruction in the literature and demonstrates a low complication rate and short length of stay. See Video Abstract . RECTOPEXIA Y SACROCOLPOPEXIA ROBTICA VENTRAL COMBINADAS CON MALLA PARA EL PROLAPSO DE RGANOS PLVICOS MULTICOMPARTIMENTALES: ANTECEDENTES:El tratamiento multiespecializado debe ser el enfoque preferido para el tratamiento de la disfunción del suelo pélvico, ya que a menudo hay prolapso multicompartimental.OBJETIVO:Evaluar la seguridad de la rectopexia robótica combinada con malla ventral y fijación uterina o vaginal para el tratamiento del prolapso multicompartimental de órganos pélvicos en nuestra institución.DISEÑO:Análisis retrospectivo.AJUSTES:Centro académico de referencia terciarioPACIENTES:Todos los pacientes que se sometieron a un enfoque robótico y un procedimiento combinado y se discutieron en una reunión quincenal del equipo multidisciplinario sobre el piso pélvico.MEDIDAS DE RESULTADO:Tiempo operatorio, pérdida de sangre intraoperatoria y complicaciones. Puntuación de cuantificación del prolapso de órganos pélvicos posoperatorio, duración de la estancia hospitalaria, morbilidad a 30 días y reingreso.RESULTADOS:De 2018 a 2021, se realizaron 321 operaciones de pacientes con prolapso multicompartimental. La edad media fue 63.4 años. La disfunción del suelo pélvico predominante fue el prolapso rectal en 170 casos (60%). Las puntuaciones de cuantificación del prolapso de órganos pélvicos fueron II en 146 pacientes (53%), III en 121 (44%) y IV en 9 (3%); 315 de los 323 casos incluyeron rectopexia robótica de malla ventral (98%). Se realizó sacrocolpopexia o sacrohisteropexia en 281 pacientes (89%). Otros procedimientos incluyeron 175 histerectomías (54%), 104 ooforectomías (32%), 151 procedimientos de cabestrillo (47%), 149 reparaciones posteriores (46%) y 138 reparaciones de cistocele (43%). El tiempo operatorio para la rectopexia con malla ventral fue de 211 minutos y la reconstrucción combinada del piso pélvico de 266 minutos. La estancia media fue de 1.6 días. Ocho pacientes reingresaron dentro de los 30 días, 1 con dolor de cabeza intenso y 7 pacientes con complicaciones posoperatorias (2.5%): colección pélvica y colección perirrectal, ambas requirieron drenaje radiológico. Cuatro complicaciones requirieron reoperación: absceso epidural, obstrucción del intestino delgado, enterotomía omitida que requirió resección y retención urinaria que requirió revisión del cabestrillo. No hubo mortalidades.LIMITACIONES:Estudio retrospectivo unicéntrico.CONCLUSIONES:Un enfoque robótico combinado para el prolapso multicompartimental de órganos pélvicos es un procedimiento seguro y viable con una tasa relativamente baja de morbilidad y ninguna mortalidad. Esta es la serie de mayor volumen de reconstrucción robótica combinada del suelo pélvico en la literatura y demuestra una baja tasa de complicaciones y una estancia hospitalaria corta. (Traducción-Dr. Aurian Garcia Gonzalez )See Editorial on page 195.

Multicenter phase II trial of transanal total mesorectal excision for rectal cancer: preliminary results.

BACKGROUND: Transanal TME (taTME) combines abdominal and transanal dissection to facilitate sphincter preservation in patients with low rectal tumors. Few phase II/III trials report long-term oncologic and functional results. We report early results from a North American prospective multicenter phase II trial of taTME (NCT03144765). METHODS: 100 patients with stage I-III rectal adenocarcinoma located ≤ 10 cm from the anal verge (AV) were enrolled across 11 centers. Primary and secondary endpoints were TME quality, pathologic outcomes, 30-day and 90-day outcomes, and stoma closure rate. Univariable regression analysis was performed to assess risk factors for incomplete TME and anastomotic complications. RESULTS: Between September 2017 and April 2022, 70 males and 30 females with median age of 58 (IQR 49-62) years and BMI 27.8 (IQR 23.9-31.8) kg/m2 underwent 2-team taTME for tumors located a median 5.8 (IQR 4.5-7.0) cm from the AV. Neoadjuvant radiotherapy was completed in 69%. Intersphincteric resection was performed in 36% and all patients were diverted. Intraoperative complications occurred in 8% including 3 organ injuries, 2 abdominal and 1 transanal conversion. The 30-day and 90-day morbidity rates were 49% (Clavien-Dindo (CD) ≥ 3 in 28.6%) and 56% (CD ≥ 3 in 30.4% including 1 mortality), respectively. Anastomotic complications were reported in 18% including 10% diagnosed within 30 days. Higher anastomotic risk was noted among males (p = 0.05). At a median follow-up of 5 (IQR 3.1-7.4) months, 98% of stomas were closed. TME grade was complete or near complete in 90%, with positive margins in 2 cases (3%). Risk factors for incomplete TME were ASA ≥ 3 (p = 0.01), increased time between NRT and surgery (p = 0.03), and higher operative blood loss (p = 0.003). CONCLUSION: When performed at expert centers, 2-team taTME in patients with low rectal tumors is safe with low conversion rates and high stoma closure rate. Mid-term results will further evaluate oncologic and functional outcomes.

Discordance in Total Mesorectal Excision Specimen Grading in a Prospective Phase 2 Multicenter Rectal Cancer Trial: Are We Overestimating the Quality of Our Resections?

OBJECTIVES: To report the results of a rigorous quality control (QC) process in the grading of total mesorectal excision (TME) specimens during a multicenter prospective phase 2 trial of transanal TME. BACKGROUND: Grading of TME specimens is based on the macroscopic assessment of the mesorectum and standardized through synoptic pathology reporting. TME grade is a strong predictor of outcomes with incomplete (IC) TME associated with increased rates of local recurrence relative to complete or near complete (NC) TME. Although TME grade serves as an endpoint in most rectal cancer trials, in protocols incorporating centralized review of TME specimens for quality assurance, discordance in grading and the management thereof has not been previously described. METHODS: A phase 2 prospective transanal TME trial was conducted from 2017 to 2022 across 11 North American centers with TME quality as the primary study endpoint. QC measures included (1) training of site pathologists in TME protocols, (2) blinded grading of de-identified TME specimen photographs by central pathologists, and (3) reconciliation of major discordance before trial reporting. Cohen Kappa statistic was used to assess agreement in grading. RESULTS: Overall agreement in grading of 100 TME specimens between site and central reviewer was rated as fair, (κ = 0.35; 95% CI: 0.10-0.61; P < 0.0001). Concordance was noted in 54%, with minor and major discordance in 32% and 14% of cases, respectively. Upon reconciliation, 13/14 (93%) major discordances were resolved. Pre versus postreconciliation rates of complete or NC and IC TME are 77%/16% and 7% versus 69%/21% and 10%. Reconciliation resulted in a major upgrade (IC-NC; N = 1) or major downgrade (NC/C-IC, N = 4) in 5 cases overall (5%). CONCLUSIONS: A 14% rate of major discordance was observed in TME grading between the site and central reviewers. The resolution resulted in a major change in final TME grade in 5% of cases, which suggests that reported rates or TME completeness are likely overestimated in trials. QC through a central review of TME photographs and reconciliation of major discordances is strongly recommended.

Large rectal diverticulum in the setting of pelvic organ prolapse treated with robotic ventral mesh rectopexy: a case report.

Background: Rectal diverticula are a very rare occurrence compared to diverticula of the colon. They are reported to account for only 0.08% of all diverticulosis. Diverticula of the rectum can be caused by congenital or acquired factors. The majority are asymptomatic, diagnosed incidentally, and require no treatment. The low incidence of rectal diverticulosis may be attributed to the unique anatomical structure and physiological environment of the rectum. However, complications can arise and may necessitate surgical or endoscopic treatment. Case Description: We report the case of a 72-year-old female with a history of diabetes mellitus, hyperlipidemia, and hypothyroidism who presented to the colorectal surgery clinic with symptoms of constipation of nearly a 50-year duration. The patient underwent an anorectal exam under anesthesia which revealed a 3 cm defect in the left levator muscles with herniated rectal wall. A large left lateral rectal diverticulum was diagnosed during the work-up for pelvic organ prolapse on defecography. She underwent robotic assisted ventral mesh rectopexy and recovered uneventfully. After 1 year of follow-up, the patient is asymptomatic, and the control colonoscopy shows no signs of the rectal diverticulum. Conclusions: Rectal diverticula can present in the setting of pelvic organ prolapse and can be safely managed with ventral mesh rectopexy.

Small Bowel Obstruction.

Small bowel obstruction (SBO) remains a common problem for surgeons and nonsurgeons alike. Management of SBO has shifted from primarily being surgical to a nonoperative approach, which can be attributed to a multitude of reasons, including better understanding of the pathophysiology of SBO, the advent of laparoscopy, and improvement in diagnostic imaging. But given the nature of SBO, the need for surgical consultation continues to remain a necessity. This article will review the etiology, diagnosis, and management of SBO.

Achieving Opioid-Free Major Colorectal Surgery: Is It Possible?

INTRODUCTION: Opioid analgesia remains the mainstay of postoperative pain management strategies despite being associated with many adverse effects. A specific opioid-free protocol was designed to limit opioid usage. OBJECTIVE: The aim of the study was to audit the opioid-free rate within this protocol and to identify factors that might contribute to opioid-free surgery. METHODS: A retrospective study of all elective patients receiving abdominal colorectal surgery at the Center for Colon and Rectal Surgery at AdventHealth over 6 months was performed. Data on demographics, indications, perioperative management, outcomes, and inpatient and outpatient analgesic requirements were collected with subsequent analysis. RESULTS: A total of 303 consecutive patient records were analyzed. Approximately two-thirds (67.7%) of patients did not receive narcotics once they left the postanesthesia care unit as an inpatient. One-third of patients (32.0%) did not receive narcotic analgesia within 30 days of surgery as an outpatient. Patients in the opioid-free cohort were significantly older and had a malignant indication, less perioperative morbidity, and a shorter length of stay. CONCLUSIONS: Our study demonstrates that opioid-free analgesia is indeed possible in major colorectal surgery. Study limitations include its retrospective nature and that it is from a single institution. Despite these limitations, this study provides proof of concept that opioid-free colorectal surgery is possible within a specific protocol.

Defining the learning curve for transanal total mesorectal excision for rectal adenocarcinoma.

BACKGROUND: Early observational data suggest that this approach is safe and feasible, but it is technically challenging and the learning curve has not yet been determined. The objective of this study was to determine the number of cases required achieve proficiency in transanal total mesorectal excision (TA-TME) for rectal adenocarcinoma. METHODS: All TA-TME cases performed from 03/2012-01/2017 at a single high-volume tertiary care institution for rectal adenocarcinoma were included. A cumulative summation (CUSUM) analysis was performed to determine the number of cases required to reach proficiency, defined as high-quality TME (complete or near-complete mesorectal envelope, negative distal (DRM), and circumferential resection (> 1 mm; CRM) margin). The acceptable and unacceptable rates of good quality TME were defined based on the incidence of high-quality TME in laparoscopic (unacceptable rate = 81.7%) and open (acceptable rate = 86.9%) arms of the ACOSOG Z6051 trial. RESULTS: A total of 87 consecutive cases were included with mean tumor height 4.8 cm (SD 2.7) and 80% (70/87) received neoadjuvant chemoradiation. Post-operative morbidity occurred in 44% (38/87) of cases, including 21% (18/87) readmissions. Median length of stay was 4 days [IQR 3-8]. A good quality TME was performed in 95% (83/87) of cases including 98% (85/87) negative CRM, 99% (86/87) negative DRM, and 99% (86/87) complete or near-complete mesorectal envelope. CUSUM analysis reported that the good quality TME rate reaches an acceptable rate after 51 cases overall, and 45 cases if abdominoperineal resections are excluded. CONCLUSION: TA-TME is a complex technique that requires a minimum of 45-51 cases to reach an acceptable incidence of high-quality TME and lower operative duration.

Early experience with the Senhance®-laparoscopic/robotic platform in the US.

The introduction of new robotic platforms will grow considerably in the near future as several manufacturers are in the developing stages of different innovative systems. One of the newest systems, the Senhance® platform (TransEnterix Surgical Inc., Morrisville, NC, USA) has been utilized in a variety of cases in Europe but only recently approved for limited clinical use in the United States. Here, we present our initial experience with this state-of-the-art system in patients requiring a variety of procedures.

Establishing the learning curve of transanal minimally invasive surgery for local excision of rectal neoplasms.

INTRODUCTION: Transanal minimally invasive surgery (TAMIS) is an endoscopic operating platform for local excision of rectal neoplasms. However, it may be technically demanding, and its learning curve has yet to be adequately defined. The objective of this study was to determine the number of TAMIS procedures for the local excision of rectal neoplasm required to reach proficiency. METHODS AND PROCEDURES: All TAMIS cases performed from 07/2009 to 12/2016 at a single high-volume tertiary care institution for local excision of benign and malignant rectal neoplasia were identified from a prospective database. A cumulative summation (CUSUM) analysis was performed to determine the number of cases required to reach proficiency. The main proficiency outcome was rate of margin positivity (R1 resection). The acceptable and unacceptable R1 rates were defined as the R1 rate of transanal endoscopic microsurgery (TEM-10%) and traditional transanal excision (TAE-26%), which was obtained from previously published meta-analyses. Comparisons of patient, tumor, and operative characteristics before and after TAMIS proficiency were performed. RESULTS: A total of 254 TAMIS procedures were included in this study. The overall R1 resection rate was 7%. The indication for TAMIS was malignancy in 57%. CUSUM analysis reported that TAMIS reached an acceptable R1 rate between 14 and 24 cases. Moving average plots also showed that the mean operative times stabilized by proficiency gain. The mean lesion size was larger after proficiency gain (3.0 cm (SD 1.5) vs. 2.3 cm (SD 1.3), p = 0.008). All other patient, tumor, and operative characteristics were similar before and after proficiency gain. CONCLUSIONS: TAMIS for local excision of rectal neoplasms is a complex procedure that requires a minimum of 14-24 cases to reach an acceptable R1 resection rate and lower operative duration.

Transanal Minimally Invasive Surgery for Local Excision of Benign and Malignant Rectal Neoplasia: Outcomes From 200 Consecutive Cases With Midterm Follow Up.

OBJECTIVE: This study describes the outcomes for 200 consecutive transanal minimally invasive surgery (TAMIS) local excision (LE) for rectal neoplasia. BACKGROUND: TAMIS is an advanced transanal platform that can result in high quality LE of rectal neoplasia. METHODS: Consecutive patients from July 1, 2009 to December 31, 2015 from a prospective institutional registry were analyzed. Indication for TAMIS LE was endoscopically unresectable benign lesions or histologically favorable early rectal cancers. The primary endpoints were resection quality, neoplasia recurrence, and oncologic outcomes. Kaplan-Meier survival analyses were used to describe disease-free survival (DFS) for patients with rectal adenocarcinoma that did not receive immediate salvage radical surgery. RESULTS: There were 200 elective TAMIS LE procedures performed in 196 patients for 90 benign and 110 malignant lesions. Overall, a 7% margin positivity and 5% fragmentation rate was observed. The mean operative time for TAMIS was 69.5 minutes (SD 37.9). Postoperative morbidity was recorded in 11% of patients, with hemorrhage (9%), urinary retention (4%), and scrotal or subcutaneous emphysema (3%) being the most common. The mean follow up was 14.4 months (SD 17.4). Local recurrence occurred in 6%, and distant organ metastasis was noted in 2%. Mean time to local recurrence for malignancy was 16.9 months (SD 13.2). Cumulative DFS for patients with rectal adenocarcinoma was 96%, 93%, and 84% at 1-, 2-, and 3-years. CONCLUSIONS: For carefully selected patients, TAMIS for local excision of rectal neoplasia is a valid option with low morbidity that maintains the advantages of organ preservation.

Uptake of Transanal Total Mesorectal Excision in North America: Initial Assessment of a Structured Training Program and the Experience of Delegate Surgeons.

BACKGROUND: Transanal total mesorectal excision is a new approach to curative-intent rectal cancer surgery. Training and surgeon experience with this approach has not been assessed previously in America. OBJECTIVE: The purpose of this study was to characterize a structured training program and to determine the experience of delegate surgeons. DESIGN: Data were assimilated from an anonymous, online survey delivered to attendees on course completion. Data on surgeon performance during hands-on cadaveric dissection were collected prospectively. SETTINGS: This study was conducted at a single tertiary colorectal surgery referral center, and cadaveric hands-on training was conducted at a specialized surgeon education center. MAIN OUTCOME MEASURES: The main outcome measurement was the use of the course and surgeon experience posttraining. RESULTS: During a 12-month period, eight 2-day transanal total mesorectal excision courses were conducted. Eighty-one colorectal surgeons successfully completed the course. During cadaveric dissection, 71% achieved a complete (Quirke 3) specimen; 26% were near complete (Quirke 2), and 3% were incomplete (Quirke 1). A total of 9.1% demonstrated dissection in the incorrect plane, whereas 4.5% created major injury to the rectum or surrounding structures, excluding the prostate. Thirty eight (46.9%) of 81 surgeon delegates responded to an online survey. Of survey respondents, 94.6% believed training should be required before performing transanal total mesorectal excision. Posttraining, 94.3% of surgeon delegates planned to use transanal total mesorectal excision for distal-third rectal cancers, 74.3% for middle-third cancers, and 8.6% for proximal-third cancers. The most significant complication reported was urethral injury; 5 were reported by the subset of survey respondents who had performed this operation postcourse. LIMITATIONS: The study was limited by inherent reporting bias, including observer and recall biases. CONCLUSIONS: Although this structured training program for transanal total mesorectal excision was found to be useful by the majority of respondents, the risk of iatrogenic injury after training remains high, suggesting that this training pedagogy alone is insufficient. See Video Abstract at http://links.lww.com/DCR/A335.

Transanal Minimally Invasive Surgery.

Transanal minimally invasive surgery (TAMIS) was first described in 2010 as a crossover between single-incision laparoscopic surgery and transanal endoscopic microsurgery (TEM) to allow access to the proximal and mid-rectum for resection of benign and early-stage malignant rectal lesions. The TAMIS technique can also be used for noncurative intent surgery of more advanced lesions in patients who are not candidates for radical surgery. Proper workup and staging should be done before surgical decision-making. In addition to the TAMIS port, instrumentation and set up include readily available equipment found in most operating suites. TAMIS has proven its usefulness in a wide range of applications outside of local excision, including repair of rectourethral fistula, removal of rectal foreign body, control of rectal hemorrhage, and as an adjunct in total mesorectal excision for rectal cancer. TAMIS is an easily accessible, technically feasible, and cost-effective alternative to TEM.

Transanal minimally invasive surgery (TAMIS) for local excision of benign neoplasms and early-stage rectal cancer: efficacy and outcomes in the first 50 patients.

BACKGROUND: Since its inception in 2009, transanal minimally invasive surgery has been used increasingly in the United States and internationally as an alternative to local excision and transanal endoscopic microsurgery for local excision of neoplasms in the distal and mid rectum. Despite its increasing acceptance, the clinical benefits of transanal minimally invasive surgery have not yet been validated. OBJECTIVE: The aim of this study is to assess the adequacy of transanal minimally invasive surgery for the local excision of benign and malignant lesions of the rectum. DESIGN: This is a retrospective analysis of consecutive patients who underwent transanal minimally invasive surgery for local excision of neoplasms at a single institution. SETTINGS: The study was conducted by a single group of colorectal surgeons at a tertiary referral center. PATIENTS: Eligible patients with early-stage rectal cancer and benign neoplasms were offered transanal minimally invasive surgery as a means for local excision. Data from these patients were collected prospectively in a registry. MAIN OUTCOME MEASURES: The primary outcome measures included the feasibility of transanal minimally invasive surgery for local excision, resection quality, and short-term clinical results. RESULTS: : Fifty patients underwent transanal minimally invasive surgery between July 2009 and December 2011. Twenty-five benign neoplasms, 23 malignant lesions, and 2 neuroendocrine tumors were excised. All lesions were excised using transanal minimally invasive surgery without conversion to an alternate transanal platform. The average length of stay was 0.6 days (range, 0-6), and 68% of patients were discharged on the day of surgery. The average distance from the anal verge was 8.1 cm (range, 3-14 cm). All lesions were excised completely with only 2 fragmented specimens (4%). All specimens were removed with grossly negative margins, although 3 (6%) were found to have microscopically positive margins on final pathology. There were 2 recurrences (4%) at 6- and 18-month follow-up. Early complications occurred in 3 patients (6%). No long-term complications were observed at a median follow-up of 20 months. LIMITATIONS: The study was limited by its retrospective nature and midterm follow-up. CONCLUSIONS: Transanal minimally invasive surgery is an advanced transanal platform that provides a safe and effective method for resecting benign neoplasms, as well as carefully selected, early-stage malignancies of the mid and distal rectum.