Anatomy of the rectum and anal canal

Collectively the rectum and anal canal constitute the very terminal segment of the large intestine, and thus of the entire gastro-intestinal tract. Their distal location renders the rectum and anal canal readily accessible to direct inspection and examination. The prime function of the rectum is to act as a distensible reservoir for faeces, while the anal canal incorporates in its wall a powerful muscular sphincter which is of paramount importance in the mechanism of faecal continence. Diseases of the rectum and anal canal, both benign and malignant, account for a very large part of colorectal surgical practice worldwide. This article emphasizes the clinically and surgically-relevant aspects of the anatomy of the rectum and anal canal.     

Anatomy of the rectum and anal canal

The rectum and anal canal are the terminal portions of large intestine and the entire gastrointestinal tract. They are thus readily accessible to direct inspection and examination. The rectum functions as a distensible reservoir for faeces, while the anal canal possesses a powerful muscular sphincter in its wall which is important in maintaining faecal continence. Diseases of the rectum and anal canal, both benign and malignant, account for a very large part of colorectal surgical practice worldwide. This article emphasizes the clinically and surgically relevant aspects of the anatomy of the rectum and anal canal.     

The anatomy of the rectum and anal canal

Diseases of the rectum and anal canal, both benign and malignant, account for a very large part of colorectal surgical practice in the UK. This article emphasizes the surgically-relevant aspects of the anatomy of the rectum and anal canal.     

Anatomy of the rectum and anal canal

Diseases of the rectum and anal canal, both benign and malignant, account for a very large part of colorectal surgical practice in the UK. This article emphasizes the surgically relevant aspects of the anatomy of the rectum and anal canal.     

Successful operation for imperforate anus and imperforate rectum: Three year follow-up report

A newborn infant, born with complete absence of the anus, sphincter, anal canal and rectum, was successfully operated upon via proctoplasty eighteen hours after birth, bringing down the sigmoid colon to serve as the new anal canal and rectum. The boy is now three years old and normal in every other respect. The formation of scar in the new anal canal, together with more progressive use of the gluteus maximus muscles, has effectuated very good control of bowel movements. The author has proctoscoped the boy several times during the past year, never finding evidence of the rectal valves, or so-called folds of Houston. This, together with the appearance of the intestinal anatomy at the time of operation, is the basis for the author's conviction that it is not the rectum, but rather the sigmoid colon, which is now functioning as an anal canal and rectum.     

Temperature gradient between the rectum and the anal canal: evidence against the role of temperature sensation as a sensory modality in the anal canal of normal subjects

Temperature difference between the rectum and anal canal is a fundamental requirement for the hypothesis that temperature sensation is of physiological importance in discrimination of anorectal contents occurring during the 'sampling reflex'. The temperature gradient between the rectum and the anal canal was measured in 47 normal subjects (mean age 51.6 years +/- 16.8 s.d., 24 men). The maximum mean difference in temperature between the rectum and the anal canal was 0.13 degrees C (0.06-0.19, 95 per cent confidence intervals) and occurred 4 cm from the anal verge. This difference is too small to be detected by the anal canal mucosa. Under normal physiological circumstances the conscious appreciation of temperature of faeces passing from the rectum to the anal canal is impossible during the anorectal sampling reflex.     

Are there still surgical indications in therapy of anal carcinoma?

The development of combined radio-chemotherapy according to Nigro has had a big influence on the therapy concept of the anal canal carcinoma. Due to the successful oncological treatment combined with a possible continence preservation, a rectum extirpation is rarely indicated. Surgical indications in the therapy concept of anal canal carcinoma are large, sphincter destroying tumors, treatment complications, therapy resistant progression and the therapy of lymph node- and organ metastases. In the therapy concept of the cancer of the anal margin, the local excision as a primary therapy is of central interest in the current literature. The introduction of plastic surgery in the treatment of even vast tumors leads to adequate results of the oncological and functional treatment. The abdomino-perineal rectum extirpation is exceptionally indicated for large, sphincter destroying tumors.     

Anal cancer: current concepts and treatment results

37 patients were treated upon carcinoma of the anal canal or anal margin between 1977 and 1989. Although combined radiochemotherapy is of increasing interest as the treatment of choice our patients who underwent radical surgery in form of abdominoperineal rectum resection only had a very good outcome. Combined multimodal therapy by radiation and chemotherapy may possibly be able to reduce the rate of necessary resections. Difficulties in finding out a relapse of disease after such treatments are discussed. The own experience with combined radio-chemotherapy is not large enough at the present time to make significant statements. Long term results have to be expected yet. Abdominoperineal rectum resection as a means of radical surgery still has its place in the spectrum therapeutic modalities of treating anal carcinoma.     

Anal canal melanoma-- case report

Anal canal melanoma is a rare disease comprising 1% of all colorectal ie. anal malignant tumours with very poor long term prognosis. Its significant biologic aggressivity is the consequence of the tendency towards lymphatic, local and hematogenous spread. At the moment of diagnosis even 30% of the patients have distant metastases. Surgical intervention represents the only possibility for cure. Modern approach to the anal canal melanoma treatment implies two types of intervention: wide local excision preserving the sphincter mechanism and abdominoperineal resection of the rectum. There are numerous dillemas about the choice of surgery in particular disease stages. The authors report on a 61 years old women in which anal canal melanoma with left inguinal lymphatic metastases was detected during the inspection of "haemorrhoids". After the diagnosis was established, abdominoperineal resection of the rectum was performed with dissection of both inguinal regions.     

A study of the effect of distension of the rectosigmoid junction on the rectum and anal canal with evidence of a rectosigmoid-rectal reflex

PURPOSE: To elucidate the role of the rectosigmoid junction (RSJ) in the mechanism of defecation. METHOD: Fourteen healthy volunteers were enrolled in the study (10 men, 4 women; mean age 38.2 +/- 10.6 years). The pressures in the rectum, anal canal, and RSJ as well as rectal balloon expulsion were recorded in response to balloon distension of the RSJ in increments of 10 ml of carbon dioxide (CO2) to 50 ml. The experiments were repeated after individual anesthetization of the RSJ, rectum, and anal canal. The expulsion of a 50-ml distended balloon located in the anesthetized rectum was tested. RESULTS: RSJ distension with 10 ml of CO2 produced no significant pressure changes in the RSJ, rectum, or anal canal. A 20-ml distension effected a significant pressure rise in the RSJ (P < 0.05) and the rectum (P < 0.01) and a decline in the anal canal (P < 0.05); the rectal balloon was expelled to the exterior. Similar pressure changes (P > 0.05) were recorded with a 30-, 40-, and 50-ml balloon distension. The mean latency for the RSJ response was 12.6 +/- 2.2 ms and for the rectum 15.8 +/- 2.6 ms. The balloon, distended with 50 ml of CO2 and located in the rectum, was not expelled to the exterior. Balloon expulsion occurred only with distension with volumes of above 80 ml. Individual anesthetization of the RSJ, rectum, and anal canal followed by RSJ distension produced no significant pressure changes in RSJ, rectum, and anal canal as well as no rectal balloon expulsion. CONCLUSION: The rectal contraction upon RSJ distension affirms the hypothesis of the possible involvement of a reflex, which we term "rectosigmoid-rectal reflex." This reflex relationship is evidenced by reproducibility and its absence on anesthetization of either the RSJ or the rectum, both presumably representing the two arms of the reflex arc. It is postulated that stools passing from the sigmoid colon to the rectum distend the RSJ and evoke the rectosigmoid-rectal reflex, which produces rectal contraction. The role of the reflex in defecation disorders needs to be studied.     

Contribution of the pudendal nerve to sensation of the distal rectum

BACKGROUND: Anal and rectal sensory mechanisms and pudendal nerve function are important in the control of faecal continence. The contribution of the pudendal nerve to sensation of the distal rectum was investigated. METHODS: Heat thresholds in the anal canal, distal and mid rectum were measured using a specially designed thermoprobe. Rectal sensory threshold volumes were measured using the balloon distension method. Needle electrodes were inserted into the external anal sphincter. Pudendal nerve block was performed through a perineal approach, and completeness assessed by loss of electromyographic activity. Heat and rectal volume thresholds were measured again following unilateral and bilateral pudendal nerve block. RESULTS: The technique was successful in four of six volunteers. Bilateral pudendal nerve block produced complete anaesthesia to heat in the anal canal (P = 0.029), but had no effect on heat thresholds in the distal or mid rectum. Rectal sensory threshold volumes were also unaffected by pudendal nerve anaesthesia. CONCLUSION: Anal canal sensation is subserved by the pudendal nerve, but this nerve is not essential to nociceptive sensory mechanisms in the distal or mid rectum. The transition between visceral control mechanisms in the lower rectum and somatic mechanisms in the anal canal may have functional importance in the initiation of defaecation and the maintenance of continence.     

Anorectal sampling: a comparison of normal and incontinent patients

It has been suggested that sampling of rectal contents by the anal canal may play a role in the continence mechanism. To investigate this concept we studied 18 patients with faecal incontinence and 18 age and sex matched controls. A microtransducer catheter was positioned so that pressures were recorded from the rectum, the junction of the upper and middle thirds of the anal canal and the lower anal canal. Recordings were taken at rest and while distending the rectum with air in a balloon, and then with air injected freely into the rectum. Sampling (equalization of the rectal and upper anal canal pressures) was seen to occur spontaneously in 16 of the controls and only 6 of the incontinent group (P less than 0.02) and induced sampling occurred at a higher rectal volume in the incontinent group than in controls for freely injected air (P less than 0.002). Defective anorectal sampling may be an important contributory factor in the pathogenesis of anorectal incontinence.     

Technical tips for intersphincteric resection: how to take out the rectum

Intersphincteric resection (ISR) is an ideal technique that preserves the anus, regardless of whether the internal anal sphincter is removed. However, it is difficult to dissect the anterior wall of the rectum from the adjacent organs. We herein describe a safe and useful ISR technique which draws out the rectum through the anus. The intersphincteric space (ISS) between the internal and external anal sphincter muscles was first transabdominally dissected. Next, the transanal dissection was advanced into the ISS bilaterally from the posterior side without dissecting the anterior wall of the anal canal, and the sigmoid colon and rectum were drawn out through the anus. Dissection between the anterior wall of the rectum and prostate/vagina could be easily performed under direct vision. This technique enables the dissection without any risk of a positive surgical margin or unexpected bleeding, and avoids injury to adjacent organs. This technique seems to be a safe and useful dissection technique for approaching the anterior wall of the anal canal.     

肛门直肠畸形术后排粪失禁患儿盆腔磁共振成像表现及其临床意义

目的通过肛门直肠畸形术后排粪失禁患儿的盆腔MRI表现,了解盆底肌的形态,直肠、肛管的形态和位置,以及脊髓和骶骨的发育,为分析排粪失禁的原因及制订治疗方案提供客观依据。方法回顾性分析2009年9月至2011年12月间山东大学第二医院收治的34例肛门直肠畸形术后排粪失禁患儿的临床和影像资料,其中男2l例,女13例,年龄3,14岁。应用1．5TMR扫描仪,常规行轴位、冠状位及矢状位扫描,观察肛门括约肌、耻骨直肠肌和提肛肌、直肠、肛管的形态,以及脊髓、骶骨的发育情况。结果MRI检查提示：肛门外括约肌发育不良18例,耻骨直肠肌发育不良23例,肛提肌发育不良27例;直肠位置异常6例,直肠扩张12例,肛直角增大11例;肛管周围脂肪组织5例;合并神经管闭合不全2例,Currarino综合征2例,骶骨发育不全11例,直肠尿道瘘2例。以上影像学结果均经临床最终证实。结论MRI可清楚显示肛门外括约肌、耻骨直肠肌和肛提肌的形态,以及直肠和肛管的形态和位置,同时还可显示脊髓和骶骨的发育情况,是评价肛门直肠畸形术后排粪失禁患儿非常有价值的检查方法。     

Preservation of continence after ileoanal anastomosis by the coordination of ileal pouch and anal canal motor activity.

Nocturnal incontinence may occur after ileoanal anastomosis and may be related to loss of an effective anal canal pressure barrier during sleep; how pressure and contractions in the proximal bowel influence this barrier is unknown. Our aim was to evaluate the relationship between anal canal pressure and contractions and contractile activity of the pouch in continent subjects after ileal pouch-anal anastomosis (IPAA) and of the rectum in normal controls. A fully ambulatory system for 24-hour pressure recording was used. A flexible transducer catheter was introduced endoscopically so that sensors were at 2, 3, 8, 12, 16, and 24 cm from the anal orifice in 12 healthy controls (7 men, 5 women, mean age: 35 years) and 7 fully continent IPAA patients (4 men, 3 women, mean age: 34 years) more than 12 months postoperatively. Twenty-four hour spontaneous motor activity was stored in a 2.5 megabyte (MB) digital portable recorder. Mean anal canal pressure was calculated, and rectal motor complexes and ileal pouch large pressure waves were characterized. During sleep, resting anal canal pressures were similar in the two groups (72 +/- 12 mm Hg in controls versus 66 +/- 9 mm Hg in IPAA patients [mean +/- standard deviation (SD)], p = NS), but anal canal pressure showed cyclic relaxations (periodicity: 95 +/- 11 min in controls, 54 +/- 18 min in IPAA patients, p less than 0.05), during which the mean pressure trough was 15 +/- 4 mm Hg in controls and 14 +/- 5 mm Hg in IPAA patients (p = NS). In the control patients, during sleep, a mean of six rectal motor complexes were identified (range: 3 to 9). In patients with IPAA, during sleep, a mean of eight large pressure waves per hour were identified (range: 2 to 20). Importantly, in both controls and patients, rectal motor complexes or large pressure waves were always accompanied by rapid return of anal canal pressure from trough to basal values and increased contractile activity. We concluded that, in healthy patients and in continent patients after IPAA, motor activity of the rectum and of the ileal pouch was associated with changes in pressure and contractile activity of the anal canal so that rectal- and neorectal-anal canal pressure gradient, and, in turn, fecal continence were preserved.     

Preventive Turnbull ileostomy

Turnbull soprovozhdaetsia khoroshimi rezul'tatami. Preventive Turnbull ileostomy was made in 28 patients. There were 19 male and 9 female patients aged from 18 to 77 years (mean age -- 46 years). Fifteen patients underwent reconstructive proctocolectomy with anastomosis between anal canal and J-shape ileac reservoir. Ten of them had familial polyposis, 5 patients had ulcerative colitis 3 had rectal cancer. Total mesorectumectomy with anastomosis between anal canal and J-shape colic reservoir was performed in 7 patients with cancer of middle and lower part of the rectum. Partial mesorectumectomy was performed in 4 patients with cancer of upper part of the rectum. Low anterior resection of the rectum with anastomosis between anal canal and J-shape colic reservoir was performed in 2 patients with villous adenoma. There were no specific complications. Following ileostomy closure was carried out in 25 of 28 patients. Wound infection was seen in 1 patient. It is concluded that preventive Turnbull ileostomy performed after lower colorectal, coloanal and ileonal anastomosis produces good results.     

大肠间质瘤13例临床分析

目的：探讨大肠间质瘤的诊断及治疗。方法：回顾性分析13例大肠问质瘤的病历资料，男9例，女4例，结肠2例，直肠8例．肛管3例。良性1例，潜在恶性2例，恶性10例。结肠间质瘤表现为腹块、腹痛、肠梗阻等，直肠肛管间质瘤表现为便秘、便血、肛门部疼痛或不适等。免疫组化：CD117、CD34、Vimentin多为弥漫阳性，S-100、HHF35多为阴性。经肛局部切除术3例，经骶尾局部扩大切除术1例，Hartmann术3例，Mises术3例，部分结肠切除3例，活检1例。结果：术后复发5例，3例为经肛局部切除，2例为姑息性Hartmann术。1、3、5年生存率分别为91．7%(11／12)、37．5％(3／8)、28．6％(2／7)。结论：大肠间质瘤术前不易确诊．多发于直肠、肛管，完整的外科手术切除是最有效的治疗方法。     

Offene Koloproktektomie mit ileoanaler J-Pouch-Rekonstruktion

Coloproctectomy is a visceral surgical intervention where the complete colon and rectum are removed up to the level of the pelvic floor or pectinate line and the anal canal. As a rule the anal canal and pelvic floor musculature including the anal sphincter muscle remain intact. The ileoanal J-pouch construction has become established as treatment of choice for reconstruction of the small intestine. This article presents the approach for open coloproctectomy with ileoanal J-pouch reconstruction by means of an operation video which is available on-line.     

Study of the anal sphincter in children

In dynamic study of the distal colon in children, the functional and electrophysiological methods of diagnosis developed and introduced by the authors: determination of anal reflex, electrosensitivity of the anal canal, musculocutaneous electrosensitivity, state of the genital nerve and its branches were used. The new methods of investigation permit to determine by the objective indices of the strength of the current and changes in pressure in the anal canal a state of the "sacral reflex arch" and neuromuscular apparatus of the external anal sphincter. In patients with constipation, a decrease in electrosensitivity and attenuation of reflex interconnection between the rectum and anal canal were noted.     

The rectourogenital connection in anorectal malformations is an ectopic anal canal

Histological investigation of the rectal blind pouch and rectourogenital or rectoperineal connection was performed in 10 patients with high or intermediate anorectal malformations. Nine of the patients underwent postoperative manometric evaluation. In nine of the 10 patients, transitional epithelium typical of the normal anal canal could be found in the distal rectum or rectal end of the fistulous connection. The zone of transitional epithelium was aganglionic and showed abnormally strong acetylcholinesterase reaction. A positive rectoanal inhibitory reflex was found manometrically in all cases in which the distal rectal pouch was utilized in the reconstruction of the anal canal. The slow pressure wave activity of the reconstructed anal canal was characteristic of a normal anal canal. The manometric evidence strongly suggests that there is a functional internal sphincter in high and intermediate anorectal malformations. The present study shows that in anorectal malformations the distal rectal pouch with the fistulous connection is actually an ectopic anal canal.