Anatomy for Surgical Treatment of Rectal Villous Adenomas: Transsphincteric Approach, Study notes of Anatomy

Download Anatomy for Surgical Treatment of Rectal Villous Adenomas: Transsphincteric Approach and more Study notes Anatomy in PDF only on Docsity! The Transsphincteric Approach to Mid and Low Rectal Villous Adenoma: Anatomic Basis of Surgical Treatment CHANGYUL OH, M.D.,* ALLAN E. KARK, M.D.** VILLOUS ADENOMAS in the mid and lower rectal region are frequently difficult to manage, due to the ana- tomical location and ambiguous nature of the tumor. Tumors so situated have been treated by a variety of methods. The simpler procedures of snare or electrical coagulation have been demonstrated to be inadequate, and anal excision is available only for low-lying tumors. Conversely, radical excisions are associated with a signifi- cant surgical risk. Therefore, a direct exposure of these rectal lesions is a very attractive alternative. The transsphincteric approach was first described by Bevan 6 in 1917; more recently Mason 36,37 has inde- pendently reported a modified method which provides a wider operative field and is less damaging to posterior attachments. None of the patients in the cases reported have developed fecal incontinence following this pro- cedure. In a similar fashion, the anterior part of the sphincter can be divided and repaired during labor with minimal complications.45 Thus, the full-thickness of the anal canal sphincter can be safely divided and recon- structed without fear of incontinence. Nonetheless, this simple and effective approach has not been widely adopted. It is appropriate, therefore, to explore the merits of this procedure with particular reference to its anatomi- cal features and the means of ensuring continence. Submitted for publication March 25, 1972. * Assistant Professor, Department of Surgery, the Mount Sinai School of Medicine of the City University of New York, New York City. ** Chairman and Franz W. Sichel Professor, Department of Surgery, the Mount Sinai School of Medicine of the City Uni- versity of New York, New York City. Presented to the New York Surgical Society November 1971. From the Department of Surgery, The Mount Sinai School of Medicine of the City University of New York, New York City Functional Anatomy of the Ano-rectum There is still disagreement concerning the mechanism of continence and defecation; however, four significant factors have received most emphasis: the puborectalis muscle, the innervation of the ano-rectal region, the re- ceptor bearing segments of the rectal wall (particularly the lower third) and the highly sensitive mucosa of the anal canal.14,19,20'22'23,47'48'50 The accepted view of continence and defecation holds that increased intra-rectal pressure by feces stimulates the stretch receptors of the rectum and, through a spinal reflex, smooth muscles are relaxed while the striated muscles contract. The relaxation lowers the intra-rectal tension to its previous level and, as a consequence, sphincter contraction is no longer necessary. When the stimulus is applied to the more distal portion of the rec- tum, a still greater muscular response is elicited which adapts itself to a given point to the bulk of its contents. When there is enough pressure in the lower rectum the closed segment of the upper anal canal then opens. Warning of an impending breach of defenses is provided by the very sensitive anal mucosa or, according to some, by the stretch receptor of the puborectalis muscle. This warning is answered by a voluntary contraction of the pelvic and external anal sphincter which closes the ano- rectal ring again. Through the recto-cerebral-external sphincteric reflex mechanism, when circumstances are ap- propriate, stool will be expelled voluntarily (Fig. 1). Hence, the preservation of these four vital anatomic struc- 605 Ann. Surg. * Nov. 1972606 Fic. 1. The Mechanism of Continence and Defecation. The reflex mechanisms between the rectum and internal sphincter (smooth muscle) through spinal cord and between the rectum and external sphincter (striated muscle) through cerebral pathway (Gaston). The receptor units are sparse in upper rectum and numerous in the lower-third which is essential (6-8 cm.) for continence (Gas- ton, Goligher, Parks). Defecatory sensory receptor is located in the puborectalis muscle (Scharli and Kiesewetter) or in the epithelium of the anal canal (Duthie and Gairns). tures are of the utmost importance to restore full anal function following ano-rectal surgery. Puborectalis Muscle The most important single element of the anatomic structure is the puborectalis muscle. This muscle, the ano-rectal ring, has been described by many authors: it ..longitudinal m. pubococcygeus ~~(levator) ~~;pubpuboectalis deep ext. sphinctel conjoined long, coat superfic. comp. FIG. 2. Lateral Coronal Section. The plane of puborectalis-deep external sphincter muscles is different from the levator ani (pubo- coccygeus). is the lower innermost part of the levator muscle, and intertwines with the deepest portion of the external anal sphincter. There is no line of separation or division be- tween these two structures.1'24'38'58 However, function- ally it is the most essential part of the voluntary sphincter and full fecal continence is impossible without this intact muscle sling. In 1953, Uhlenhuth 54 clearly il- lustrated the puborectalis as one of the most medial muscles in the pelvic floor: it surrounds the anal funnel at the most lateral and dorsal part of the anus and is separated there from immediate contact with the wall of the ano-rectal canal by the pubococcygeus. These re- lationships have been confirmed by Gorschb25 and Law- son.32 Our detailed studies 44 have demonstrated that the lowermost part of the pubococcygeus (levator) directly envelops the upper portion of the anal funnel where it meets with the longitudinal muscle of the rectum to form the conjoined longitudinal coat. This conjoined musculo- fibrous coat is itself surrounded by the puborectalis and the external anal sphincter. This is shown in coronal sec- tion (Figs. 2 & 3). Thus, the plane of the pubococcygeus is different from that of the puborectalis muscle which surrounds it. However, this is true only in the lateral aspect. In the mid-posterior sagittal section, these planes are less distinct and appear to be a continuation of pubococcygeus or deep portion of the external sphincter -that is, both are one plane (Fig. 4). Anatomical Landmarks of the Ano-Rectum The landmarks of the ano-rectum are by no means uni- formly described in standard texts,4 10'18'21'46 particularly in regard to the length of the anal canal, the location of the peritoneal reflection, and the recto-sigmoid junction. Few have attempted to define the differences in race, stature of sex, which account for variations in measure- ment. On the basis of our clinical observations and direct measurement of eight cadaveric specimens (five male, three female), the following scheme of clinical measure- ment is proposed. The anal canal, the lower rectum, the mid-rectum and the upper rectum are each approximately 4 cm. in length; thus the length of the ano-rectum is approxi- mately 16 cm. Because of variations of sex and stature, 2 cm. can be added for the tall male, and 2 cm. sub- tracted for the short female; thus, the ano-rectum is 16 ± 2 cm. This number can be remembered conveniently as the Rule of Four (Fig. 5). The anterior peritoneal reflection is about 8 cm. from the anal verge, +2 cm., depending on size and sex, and which gives an accurate range of measurement. The right mid-rectal value meets with the pubococcygeal line which corresponds to the anterior peritoneal reflection and the region of the mid- rectum (Fig. 5). OH AND KARK TABLE 1. Clinical Data in 7 Patients with Transsphincteric Approach Distance from Anal Verge Size Follow-up Patient Age Sex Postop. (cm) (cm) (mos.) Miscellaneous M. B. 34 F Villous Adenoma 7 5 X 6 11 Well K. E. 65 F Focal Ca. 14 4 X 3 9 Well W. N. 77 F Villous Adenoma 5 5 X 3 9 Well G. H. 66 M Villous Adenoma 7 5 X 6 3 Well L. P. 61 M Infiltr. Ca. 6 6 X 6 1 Sleeve resection. S. R. 37 F Duke's A 10 3 X 3 5 A-P resection. M .J. 91 M Infiltr. Ca. 6 Circular 2 Died of sepsis. X12 Her lesion was located 10 cm. from the anal verge, and measured 3 cm. in diameter. Via a transsphincteric ap- proach, the whole tumor was excised including part of the muscular layer. It was reported as infiltrating adeno- carcinoma but the muscle coat was free of tumor. Be- cause of the patient's youth, she underwent an abdomino- perineal resection; the resected specimen showed neither residual tumor at the operative site nor in the regional lymph nodes. The seventh patient, a 91-year-old man had a circular carpeting villous adenoma with infiltrating carcinoma which extended from 5 cm. from the anal verge to 17 cm. at the level of the recto-sigmoid junction. This had been coagulated on several occasions in the past 7 years, and the patient had suffered from mucous diarrhea for the past 3 years and was incapacitated with fecal incon- tinence for 1 year prior to operation. The postoperative course was complicated by non-healing of the posterior wound and by subsequent colostomy evisceration. The patient died of sepsis (Table 1). Discussion Contrary to general belief, complete transection of the anal sphincter does not produce fecal incontinence pro- vided careful approximation of each component of the sphincter structure is achieved. The keystone to success in the transsphincteric pro- cedure is a clear understanding of functional anatomy and its preservation. The complexity of the mechanism of anal function is not entirely understood; the four cardinal elements, puborectalis muscle, lower segment of rectal wall, intact anal mucosa and innervation of the ano-rectum have been emphasized (Fig. 1), and of these, the puborectalis muscle is the most important structure of the voluntary sphincter. It can be recognized at the upper border of the external sphincter and sur- rounds the lower part of the levator muscle (pubococ- cygeus) at the level of the ano-rectal ring (Figs. 2 & 3). Since the puborectalis intermingles with the deep ex- ternal sphincter and pubococcygeus, it is often difficult to identify it at the time of operation. Therefore, the marking sutures are an essential means of providing ac- curate anatomical repair of the wound. The ano-rectum, defined as extending from the anal verge to the recto-sigmoid junction, corresponds to the articulation of sacral segments 2 and 3. The anal canal and each third of the rectum are approximately 4 cm. in length, the total length being 16 cm.; because of varia- tion of size and sex, 16 ± 2 cm. gives a more accurate range of measurement. These measurements represent a simplified means of defining the landmarks in particular the localization of lesions of the lower two-thirds of the rectum lying between 4 and 12 cm. from the anal verge. The management of villous adenomata of the lower two-thirds of the rectum is often a difficult problem for two reasons: 1) Potential Malignancy: the reported inci- dence of malignancy in villous adenoma range from 6% to 100% with an average of about 35%15,16,27,42,53 Among the cancerous villous adenomata, four out of five are in Duke's A and B categories. The definite histologic struc- ture of this tumor must depend on the total excisional biopsy; fragmental excision or punch biopsies are totally unreliable which was proven in our four cases of car- cinoma; 2) Anatomical Location: a tumor situated 6 to 12 cm. from the anal verge fall in a notorious "no-man's land" and are difficult to deal with. Tumors lying close to the anal verge may be handled by a simple procedure such as snare or electrocoagula- tion which are often not ideal because of their incom- pleteness;'7 52'53'56 anal excision has only limited applica- tion for the low-lying tumor.9 49 Conversely, for lesions in the middle and lower rectum, complete excision of a rectal segment and primary anastomosis of bowel by the low anterior resection, Kraske's operation or abdomino- sacral approach 3,3033,51,57 are associated with a signifi- cant degree of surgical complications. Furthermore, pull- through sphincter saving procedures often result in fecal incontinence in approximately one-third of the patients in most series.2'3'7'8'23'29'35,55r59 Finally, indiscriminate ab- domino-perineal resection is hazardous in most instances. Thus, these procedures are either inadequate or are too Vol. 176 * No. 5 RECTAL VILLOUS ADENOMA 609 Ann. Surg. * Nov. 1972 TABLE 2. Transspkincteric Proctotomy Complications Maximal Follow-up Authors No. of Cases Incontinence Major Minor Years Bevan (1917) Few Obtained Good Results 5 David (1943) 15 0 1* Few** 5 Larkin (1959) 5 0 0 0 4 Granet & Paradis (1964) 10 0 0 0 7 Mason (1970) 24 0 1+ 9** 9 Mason (1970) 14 0 2++ - 8 Total 68 0 4 9 *-Recurrence villous adenoma, coagulated. **-Wound infection, healed by itself. +-Fistula closed with colostomy. + +-Recurrence Ca. Required resection. radical for the undertermined pathologic findings of mid- rectal villous adenomas. In comparison with these methods, the direct approach to the rectum via transsphincteric proctotomy (Bevan- Mason) is more effective and desirable. Of 68 cases re- ported, there has been no instance of fecal incontinence following this procedure 13,26,31,36,37 (Table 2). Mason 3 has reported 24 cases, and observed primary healing in 15 patients, delayed healing in nine, and a fistula in one. In addition, he has used this method in 14 patients with invasive carcinoma of the rectum and obtained satis- factory results except in two who developed recurrence during the 1 to 8-year follow-up period.37 In similar fashion, O'Leary in 1965 45 reviewed the re- sults of 1,224 cases of median episioproctotomy, and found there were no major complications such as fistula formation, sphincter dysfunction or wound dehiscence. This finding has been confirmed by others;5'28 Norris 43 noted only one case of flatus incontinence among the 255 cases. Thus, the complete division of the anal sphincter fol- lowed by careful primary repair of the wound does not, as is generally assumed, lead to anal dysfunction or in- continence. Furthermore, the transsphincteric procedure provides an excellent initial approach which does not preclude other procedures if the patient's status or the extent of the tumor demands it. This is demonstrated in two of our cases (S.R. 37-year-old women, and L.P. 61-year-old man), in which in these early carcinomas, additional procedures were added: an abdomino-perineal resection for the former because of the patient's youth, segmental resection for the latter because of the patient's mental unpreparedness for permanent colostomy and relatively old age. Up to the present, our policy for carcinoma of the lower two-thirds of the rectum has been based on the Miles procedure. However, Morson's recent work41 has thrown some doubt on this uniform approach. He has shown that if the tumor is confined to the mucosa or submucosa, the lymphatic metastasis is 10.9% and when it is still confined to the bowel wall the incidence was 12.1%. In those growths spreading in continuity through and beyond the bowel wall the incidence of mestastasis rose to 58.3%. Of 76 instances of early carcinoma 46 pa- tients underwent radical treatment and 30 were treated locally. The result of local excision has so far been as good as radical procedures. Since the carcinoma in vil- lous adenoma is a low-grade malignant tumor with a low metastasis rate 51,53 it seems that local excision of local- ized small carcinoma (less than 4 cm, in diameter) may well be considered as a definitive procedure. In two of our cases, one patient had a small tumor (3 x 3 cm.) which proved to be Duke's A grade following abdomino- perineal resection, and the other (6 x 6 cm.) had an infiltrating carcinoma which, following sleeve resection, also failed to demonstrate lymphatic spread. The transsphincteric approach is inadvisable in the following situations: 1) extensive and cirfumferential carpeting lesions, 2) those tumors already subjected to multiple previous electric coagulation, 3) presence of in- fection in the perineal region, 4) high location of tumor at the level of the recto-sigmoid junction. The extensive lesion as seen in M.J., the 91-year-old man, is better managed by abdomino-transsacral resection, the merit of which has been described by Localio and Stahl in 1969.33 Conclusions 1. The problem of surgical access to mid and low rectal lesions is discussed with particular reference to villous adenomas and the need for total excisional biopsy. 2. The anatomic features that help maintain continence are reviewed. The ability to cut completely across all the sphincteric mechanisms and still retain complete con- tinence is dependent on careful and accurate reopposi- tion of each separate component. 3. The transsphincteric approach provides excellent 610 OH AND KARK Vol. 176 * No. 5 RECTAL VILLOUS ADENOMA 611 exposure for complete removal of villous adenomata situated in the rectum, 6-12 cm. from the anal verge. The application of this method for local excision of small non-infiltrating carcinoma for part of the rectum is dis- cussed. References 1. Adloff, M. and Kohler, J. J.: Sacral Approach to Certain Villous Tumors of the Ampulla of the Rectum. J. Chir. (Paris), 98:19, 1969. 2. Bacon, H. E.: Abdomino-Perineal Proctosigmoidectomy with Sphincter Preservation. JAMA, 160:628, 1956. 3. Bacon H. E.: Evaluation of Sphincter Muscle Preservation and Re-establishment of Continuity in the Operative Treat- ment of Rectal and Sigmoidal Cancer. Surg. Gynecol. Obstet., 81:1131, 1945. 4. Bacon, H. E. and Recio, P. M.: Surgical Anatomy of the Colon, Rectum and Anal Canal. J. B. Lippincott, Phila- delphia, 1962. 5. Barter, R. H., Parks, J. and Tyndal, C.: Median Episiotomies and Complete Perineal Lacerations. Am. J. Obstet Gynec., 80:654, 1960. 6. Bevan, A. D.: Carcinoma of Rectum-Treatment by Local Excision. S. Clin. N. Am., 1:1233, 1917. 7. Black, B. M. and Botham, R. J.: Combined Abdomino-endo- rectal Resection for Lesions of the Mid and Upper Parts of the Rectum. Arch. Surg., 76:688, 1958. 8. Black, B. M. and Walls, J. T.: Combined Abdomino-endorectal Resection. Reappraisal of Pull-Through Procedures. S. Clin. N. Am., 47:977, 1967. 9. Blaisdell, P. C.: Anal Delivery of Rectal Tumors. Surg. Gyne- col. Obstet., 97:372, 1953. 10. Buie, L. A.: Practical Proctology, Charles C Thomas, Publisher, Springfield, Illinois, 1960. 11. Courtney, H.: Anatomy of the Pelvic Diaphragm and Anorectal Musculature as Related to Sphincter Preservation in Ano- rectal Surgery. Am. J. Surg., 79:155, 1950. 12. Crowley, R. T. and Davis, D. A.: A Procedure for Total Biopsy of Doubtful Polypoid Growth of th Lowest Large Bowel Segment. Surg. Gynecol. Obstet., 93:23, 1951. 13. David, V. C.: The Management of Polyps Occurring in the Rectum and Colon. Surgery, 14:387, 1943. 14. Duthie, H. L. and Gairns, F. W.: Sensory Nerve Endings and Sensation in the Anal Region of Man. Brit. J. Surg., 47:38, 1960. 15. Enterline, H. T., Evans, G. W., Mercado-Lugo, R., Miller, L. and Fitts, W. T.: Malignant Potential of Adenomas of Colon and Rectum. JAMA, 179:322, 1962. 16. Fisher, E. R. and Castro, A. F.: Diffuse Papillomatous Polyps (Villous Tumors) of the Colon and Rectum. Am. J. Surg., 85:146, 19153. 17. Freund, N. L.: Villous Tumors of the Rectum. Am. J. Surg., 90:873, 1955. 18. Gabriel, W. B.: The Principles and Practice of Rectal Surgery. Charles C Thomas, Springfield, Illinois, 5th Edition, 1963. 19. Gaston, E. A.: Physiological Basis for Preservation of Fecal Continence after Resection of Rectum. JAMA, 146:1486, 1951. 20. Gaston, E. A.: The Physiology of Fecal Continence. Surg. Gynecol. & Obstet., 87:280, 1948. 21. Goligher, J. C.: Surgery of the Anus, Rectum and Colon. Charles C Thomas, Second Edition, 1967. 22. Goligher, J. C.: The Functional Results after Sphincter-Saving Resections of the Rectum. Ann. Roy. Coll. Surg., Engl., 8:421, 1951. 23. Goligher, J. C., Duthie, H. L., Dedombal, F. T. and Watts, J. M.: Abdomino-Anal Pull-Through Excision for Tumor of the Mid-Third of the Rectum. A Comparison with Low Anterior Resection. Brit. J. Surg., 52:323, 1965. 24. Goligher, J. C., Leacock, A. G. and Brossy, J. J.: The Surgical Anatomy of the Anal Canal. Brit. J. Surg., 43:151, 1955. 25. Gorsch, R. V.: Proctologic Anatomy. Williams and Wilkins, Co., Baltimore, Second Edition, 1955. 26. Granet, E. and Paradis, H.: Papillary (Villous) Adenomas of the Rectum. Am. J. Gastroent., 41:627, 1964. 27. Grinnel, R. S. and Lane, N.: Benign and Malignant Adeno- matous Polyps and Papillary Adenomas of the Colon and Rectum. An Analysis of 1,856 Tumors in 1,335 Patients. Int. Obstet. Surg., 106:519, 1958. 28. Kaltreider, D. F. and Dixon, D. M.: A Study of 710 Com- plete Lacerations Following Central Episiotomy. Southern Med. J., 41:814, 1948. 29. Kennedy, J. T., McOmish, D., Bennett, R. C., Hughes, E. S. R. and Cuthbertson, A. M.: Abdomino-Anal Pull- Through Resection of the Rectum. Brit. J. Surg., 57:589, 1970. 30. Korbl, H.: Die Continenzyerhaltisse Nach Den Radicalen Operationen des Mastdarmkrebses. Arch. Klin. Chir., 101: 449, 1913. 31. Larkin, M. A.: Transsphincteric Removal of Rectal Tumors. Dis. Colon Rectum, 2:446, 1959. 32. Lawson, J. 0. N.: Recent Advances in Pediatric Surgery. Grune & Stratton, Inc., New York, Second Edition, 1969. 33. Localio, S. A. and Stahl, W. M.: Simultaneous Abdomino- transsacral Resection and Anastomosis for Mid-Rectal Can- cer. Am. J. Surg., 117:282, 1969. 34. Lockwood, R. A. and Taylor, W. A.: Posterior Surgical Ap- proach to the Rectum. Calif. Med., 85:104, 1956. 35. Mandl, F.: Uber 1000 Sakrale Mastdarmkrebsexstirpationen. Deut. Zeit. Chir., 219:3, 1929. 36. Mason, A. Y.: Surgical Access to the Rectum-A Transsphinc- teric Exposure. Proc. Roy. Soc. Med., Suppl., 63:91, 1970. 37. Mason, A. Y.: The Place of Local Resection in the Treatment of Rectal Carcinoma. Proc. Roy. Soc. Med., 63:1259, 1970. 38. Milligan, E. T. C. and Morgan, C. N.: Surgical Anatomy of the Anal Canal. Lancet, 2:1150, 1934. 39. Miller, J. H.: Removal of Large Sessile Polyps of Rectum. Am. J. Gastroent., 25:596, 1956. 40. Moran, T. F.: Transsacral Removal of Rectal Lesion. J. Int. Coll. Surg., 35:361, 1961. 41. Morson, B. C.: Factors Influencing the Prognosis of Early Cancer of the Rectum. Proc. Roy. Soc. Med., 63:607, 1970. 42. Nicoloff, D. M., Ellis, C. M. and Humphrey, E. W.: Manage- ment of Villous Adenoma of the Colon and Rectum. Arch. Surg., 97:254, 1968. 43. Norris, F.: Episioproctotomy. S. Clin. N. Am., 42:947, 1962. 44. Oh, C. and Kark, A. E.: Anatomy of the External Anal Sphincter. Brit. J. Surg., 59:717, 1972. 45. O'Leary, J. L. and O'Leary, J. A.: The Complete Episiotomy Analysis of 1224 Complete Lacerations, Sphincterotomies and Episioproctotomies. Obstet. Gynecol., 25:235, 1965.