surgical anatomy of rectum

surgical anatomy of rectum , nerve bundle , injury to nerves during TME

1. Surgical anatomy of the rectum-anatomical basis of resections Presenter-Yajnadatta Sarangi Moderator-Dr Ashok Kumar sir

2. Embryology Rectum and proximal 2/3 rd anal canal from developed from cloaca Distal anal canal developed from proctoectoderm

3. Rectum 12 to 15 cm long Surgical mobilisation provide extra 5 cm in length Upper border - Recto sigmoid junction proximal rectal border at the level of the anterior peritoneal reflection Ann Gastroenterol. 2019 Sep-Oct; 32(5): 431–440.

4. Recto sigmoid junction Surgical : Taeniae coli of the sigmoid colon splay and become indistinct ,sigmoid takeoff Radiographically : The sacral promontory Endoscopically : 15 cm from the anal verge on rigid proctoscopic examination Why important to know - when the sacral promontory is used instead of the sigmoid take-off, a cranial overextension of the proximal rectal border towards the sigmoid is inevitable – this leads to unnecessary radiation of the sigmoid colon as a result of an extended neo-adjuvant radiation field . Ann Gastroenterol. 2019 Sep-Oct; 32(5): 431–440.

5. Lower limit of rectum surgeon- ano rectal junction where puborectalis sling surrounds the r ectu m Anatomist –D entate line Radiologist-A nal verge Surgical anal Canal 2 to 5cm extend from ARJ to Anal verge Low rectal tumor -distance from lower border of tumor to top of anorectal ring Ann Gastroenterol. 2019 Sep-Oct; 32(5): 431–440.

6. Ano Rectal junction Rectum ends at ARJ(passing through lavator ani muscle) 2-3 cm in front of and a little below coccyx At the level of anorectal ring (t he level of puborectalis sling ) Anorectal junction in male corresponds to apex of prostate 4cm in front of tip of coccyx T he dentate line demarcates the superior two-thirds of the anal canal from the inferior one-third. t he dentate line serves as a visual landmark for endo- scopic and intra-operative assessment . The dentate line lies in the narrow intracanalar zone and is situated 1—2 cm below the upper edge of the internal sphincter Ann Gastroenterol. 2019 Sep-Oct; 32(5): 431–440.

7. Anal transition zone Anal transition zone begins 5mm above dentate line But histologic transition continues upto dentate line Located at this level are columns of Morgagni Anal crypts are present between these colon and 3 to 12 in number –source of perineal abcess Shakelfords surgery of alimentary tract

8. Division of rectum Distance from the anal verge rather than the dentate line Low (distal) rectal cancers are located 5 to 6 cm from the anal verge Middle rectal cancers 7 to 1 1 cm -most common site of rectal cancer Upper (proximal) rectal cancers 12 to 15 cm The anal canal is to 4 cm from the anal verge New Insights into the Surgical Anatomy of the Rectum: A Review

9. Rectal flexures Rectum is curved antero-posteriorly and laterally A-P-2 flexure Sacral flexure Perineal flexure/anorectal flexure Laterally 3 flexure

10. Houston valve Mucous membrane of rectum together with circular muscle. Layer forms 3 o4 3 semicircular permanent fold called transverse folds of rectum ( Houston's valves) Valves of Houston-folds in rectum to support the weight of feaces 3 to 4 such folds

11. Peritoneal folds Peritonium covers the anterior aspect of upper 1/3 rd of rectum Middle rectal fold corresp onds to anterior peritoneal reflection Anterior peritoneal fold –pouch of Douglas Anterior rectal tumors located at or above the anterior peritoneal reflection and invading the peritoneum are at great risk of intraperitoneal spread selection of the upper boundary of the radiation field

12. Fascia’s around rectum Pelvic fascia Parital endo pelvic fascia –covers bone and muscles of pelvis Visceral endo pelvis fascia-covers organ Parital fascia-(endopelvic fascia) obturator fascia Fascia over pyrformis Covering lavator ani Presacral fascia Visceral fascia of rectum -fascia propria OR visceral endo pevis fascia Bisset et a l, Dis Colon Rectum 2000;43:903-10.

13. Presacral fascia Presacral venous bleeding (PSB) -3% to 9.4% incidence  Most likely area of injury is the lower sacrum, where Waldeyer’s fascia is thick and may attach directly to the presacral fascia Owing to the lack of valves and increased hydrostatic pressure , bleeding from small vessels in this area can be torrential and extremely difficult to control Ligation of internal iliac artery and veins are ineffective Celentano V, Ausobsky JR, Vowden P. Surgical management of presacral bleeding. Ann R Coll Surg Engl. 2014 May;96(4):261-5.

14. Control of presacral bleed Celentano V, Ausobsky JR, Vowden P. Surgical management of presacral bleeding. Ann R Coll Surg Engl. 2014 May;96(4):261-5.

15. Parietal pelvic fascia/pre-hypogastric fascia Lies ventral to presacral fascia Dual lamellar structure Encased hypogastric nerve and pelvic splanchnic nerve Fuses with presacral fascia making it difficult to separate Ann Gastroenterol. 2019 Sep-Oct; 32(5): 431–440.

16. Denonvillier’s fascia Aigner et al noted that local condensation of collagenous fibers Heald et al noted the fascia on the anterior surface of the mesorectum with a distinct plane separating this shiny fascia and the seminal vesicles. Risk of damage to cavernous nerve to avoid damage to cavernous nerve(para sympathetic Fiber ) anterior dissection should be posterior to denonvilliers fascia expect in cases of a nterior tumo r Kulaylat MN. World J Surg Proced  2015

17. Denonvillier’s fascia D issection and excessive traction of the seminal vesicle from the 10 o'clock and 2 o'clock- might cause damage to nerve bundles Dissecting at the level of Denonvillier’s fascia may jeopardize the integrity of nerves radiating from the hypogastric nerves to the urogenital area

18. Mesorectum Extension of visceral fascia Surrounded by perirectal fascia or fascia propria Distally thinned out at mesorectum Anteriorly thin as fused with denonvillers fascia Multilayer structured Content- Lymphovascular bundle of rectum The transition from the mesosigmoid to mesorectum is indicated by the “sigmoid take off” Ann Gastroenterol. 2019 Sep-Oct; 32(5): 431–440.

19. Mesorectum Fully covers rectum except Near bifurcation of SHA near its bifurcation only present laterally and posteriorly Near lower rectum it thinned out and almost fused with rectal wall Complete removal of mesorectum is the basis of TME for carcinoma rectum Except in tumor of upper rectum partial TME/TTME can be followed Journal of Gastrointestinal Surgery  18(7)

20. Re ctosacral fascia or Waldeyer's fascia De nse connective tissue attaching the posterior wall of the rectum to presacral fascia at the third and fourth sacral vertebra. F ailure to recognize or failing to divide it sharply may result in either perforation of the rectum or hemorrhage from presacral venous plexus. Full mobilization of the rectum is not possible unless the rectosacral fascia is divide d blunt hand dissection of waldeyers fascia may cause avulsion injury of the presacral fascia S harp division of the rectosacral fascia helps pelvic dissection to reach down to the coccyx level,

21. Lateral rectal ligaments The lateral ligament as an extension of the mesorectum, anchoring it to the endopelvic fascia. Controversial(explained by Dr miles , no mentioned in original paper by Dr Heald ) Kulaylat MN,  World J Surg Proced  2015 Fishers mastery

22. Lateral rectal ligaments They are in contact with the lateral neurovascular pedicle of the rectum. The point of insertion of the lateral ligament to the endopelvic fascia is dangerously close to the uro - genital bundle. May contain neurovascular structure Sharp dissection with minimal traction on rectum help in visualizing and preserving these nerve fibers Excessive traction on rectum may cause damage to hypogastric nerve bundle Blunt dissection and clamping thsee ligaments lead to functional loss OF NERVE FUNCTION Wang GJ. Anatomy of the lateral ligaments of the rectum: a controversial point of view. World J Gastroenterol. 2010 Nov 21;16(43):5411-5

23. Lateral rectal ligaments MHA present in 22% of case Distance between rectum and pelvic plexus is between 8mm to 14mm Lateral mobilisation during TME should close to rectum to prevent damage to nerve fibers Heald RJ. The ‘Holy Plane’ of Rectal Surgery.  Journal of the Royal Society of Medicine . 1988;81(9):503-508

24. Arterial supply SHA n 81% bifurcate anterior to rectal wall and posterior to facsia propria- hence another landmark to enter the holy plane 13% of cases it trifurcate 2% cases it passes posteriorly to rectal wall Middle rectal artery present in 22% of cases Kulaylat MN,  World J Surg Proced  2015

25. Lymphatic drainage of rectum

26. Lymphatics of Rectum 2 Group –intramural and extramural Ly mph from the upper third of the rectum, drains to superior rectal nodes after transversing para- rectal nodes. t hen to inferior mesenteric nodes. Lower 1/3 rd of rectum The part proximal to the mucocutaneous junction - internal iliac nodes, common iliac nodes, and the lumbar trunks Lymphatic drainage from the anal canal inferior to the m ucocutaneous junction is exceptional to superficial inguinal nod e Upper rectum-liver metastasis Lower rectum-systemic metastasis Paty PB, Ann Surg .  2002 Oct; 236(4): 522–530.

27. Lymphatics of Rectum Mid or lower rectal cancer has a 30% chance of lymph node metastasis along the internal iliac artery and its branches. Most of lymphatics direction are cranial both intra mural and extra mural part so distal margin of 1 cm sufficient in rectal carcinoma T4 and N + tumors who have not undergone neo-adjuvant CRT have a risk of intramural invasion extending beyond 1cm in 4—7% of cases but the risk of extension beyond 2cm is close to 0% so distant margin of 1 cm sufficient Paty PB, Ann Surg .  2002 Oct; 236(4): 522–530.

28. High tie vs Low tie Advantage Tension free anastomosis More lymph node yield Compulsory when there is a common trunk between left colic artery and first sigmoid artery ( variant present in 27% of case ) Disadvantage extended mobilization Not indicated in poor risk patient Advantage not demonstrated in literature Yin TC,. Low Ligation Plus High Dissection  Versus  High Ligation of the Inferior Mesenteric Artery in Sigmoid Colon and Rectal Cancer Surgery: A Meta-Analysis. Front Oncol. 2021 Nov 11;11:774782. 

29. High tie vs Low tie vs low ligation High-defined as ligation of this vessel at the point where the artery springs from the abdominal aorta, under cover of the 3rd part of the duodenum Low ligation- efined as ligation of this vessel immediately distal to the left colic arter M ost studies, however, have shown that ‘‘high’’ ligation of the IMA is not associated with a significant improvement of survival compared to ‘‘low’’ ligation of IMA Yin TC, Chen YC, Su WC, Chen PJ, Chang TK, Huang CW, Tsai HL, Wang JY. Low Ligation Plus High Dissection  Versus  High Ligation of the Inferior Mesenteric Artery in Sigmoid Colon and Rectal Cancer Surgery: A Meta-Analysis. Front Oncol. 2021 Nov 11;11:774782. 

30. Anatomy of pelvic nerves Supra- levator compartment Superior hypogastric plexus and hypogastric nerve T10 to L3 ,continued as of preaortic sympathetic nerves 1cm of midline and 2 cm medial to ureter Mostly Sympathetic and also contain upward fiber of pelvic splanchnic nerve Vasoconstrictor Inhibitor to muscle of rectum Motor(excitatory ) to internal sphincter carry sensation of pain Ejaculatory dysfunction – retrograde ejaculation and loss of ejaculation Urinary urgency and incontinence D. Moszkowicz et al.

31. Sympathetic nerve supply y T10,L1 , L2,L3 fibers Through superior rectal and inferior hypogastric plexus

32. Parasympathetic nerve supply S2,S3 and S4 fibers Passage via pelvic splanchnic nerve and inferior hypogastric plexuses to pelvic plexus Motor to musculature of rectum, Inhibitory to internal sphincter Carry sensation of pain and distension Detrusor contractility, vagina lubrication and genital swellings Micturation , erection and lubrication D. Moszkowicz et al.

33. Inferior hypogastric plexus IHP 3-4 mm plaque of nerve Located laterally on both side of rectum close to prostate and seminal vesicle in male Close to cervix and vaginal fornix and extends up to lateral vaginal wall and base of bladder Bulk of nerve close to vaginal fornix Both adrenergic and cholinergic Efferent Fiber of IHP innervate bladder , ureter ,seminal vesicle , prostate and membranous urethrae Cavernous nerve – erectile function D. Moszkowicz et al .

34. Inferior hypogastric plexus Lies outside of fascia propria in superficial layer of parietal fascia The para rectal fascia and perirectal adipose tissue separate lateral surface of rectum form IHP Risk of damage while proceeding with lateral dissection of rectum  Obstet Gynecol. 2006 Sep;108(3 Pt 1):529-34

35. Levator ani nerve (LAN) Newer concept Perineal branch of S4 nerve Motor to levator mucle Help in continence Run above the lateral parital pelvic fascia unlike pudental nerve which run below the pelvic floor muscle Damage lead to weaker pelvis and problem of incontinence  Obstet Gynecol. 2006 Sep;108(3 Pt 1):529-34

36. Infra levator compartment Pudental nerve –S2-S4 Perineal branch – sensory innervation to perineal skin and motor innervation to IC/BC/STP Inferior rectal nerve-EAS, Dorsal nerve to penis /clitoris Urinary incontinence/fecal incontince /sensory sexual impotence

37. Nerve injury after TME and symptoms Low anterior resection syndrome Combined faecal and urinary incontinence Long term urinary incontinence in 7 to 23% patient Combined FI and UI in 14 % of patient Poor sexual function(male –ejaculatory problem and female dyspareunia and vaginal dryness ) Dutch TME trial , PLoS Med.  2008 Oct; 5(10): e202

38. Faecal incontinence Dysfunctional pelvic floor muscle Radiation induced fibrosis of muscle of pelvic floor Damage to Levator ani nerve Levator ani nerve passes close to place where mesorectum fused with lower rectum at pelvic floor(major component) Damage to pudenal nerve -minor

39. Urinary incontinence Urge incotinence - Hypogastric nerve and pelvic plexus -sympathetic and parasympathatic Overflow incontinence Sacral splanchnic nerve-parasympathetic Stress urinary incontinence Impaired support to urethrae and bladder neck

40. The most frequent areas for neural injury while performing a TME The inferior mesenteric plexus at the origin of the IMA. IMA palpated between 2 fingers and plexus posterior to IMA A 1-1.5 cm arterial stump is adequate in order to avoid injury to plexus

41. The most frequent areas for neural injury while performing a TME The dissection of the retro rectal space may injure the hypogastric nerves, resulting in a certain degree of anorectal incontinence and urogenital dysfunction Nerves to internal sphincter, again resulting in anorectal dysfunction. Care at anterior-inferior aspect of the rectum, where nerve fibers for the internal anal sphincter from the pelvic plexus run along the neurovascular bundle, and at the anterior-lateral aspect(10 to 2o clock )

42. The superior hypogastric plexus at the level of the sacral promontory while entering the retro rectal plane At junction of mesosigmoid to mesorectum carefully dissected to displace HN dorsally constipation and intermittent defecation with tenesmus and incontinence) Dissection between parietal fascia( presacral fascia and prehypogastric nerve fascia) and visceral fascia(fascia properia ) Correct plane of dissection – just behind visceral fascia ,SHA act as a land mark

43. The most frequent areas for neural injury while performing a TME At the level of the lateral rectal ligaments, the inferior hypogastric plexus may be injured. Injury to parasympathetic innervation during low anterior resection might result in defecation disorders, a syndrome known as “low anterior resection syndrome” P revented if dissection of the lateral aspects of the rectum takes place close to lateral mesorectal wall No need to dissect the lateral ligament as there is no lymphatics in it Excessive traction may injured these nerve

44. ISSETT ETA~ Dis Colon Rectum, July 2000

45. External anal sphincter Proximal(deep) ,mid and distal part Continuation of puborectalis muscle Female EAS have a natural defect in EAS Rectal branch of pudental nerve Perianal branch of s4 The deep layers are a continuation of the deep muscles of the levator ani . u pper edge of the sphincter is easily palpable on DRE corresponding to the muscular bundles of the puborectalis

46. Internal anal sphincter Ring of smooth muscle formed by continuation of involuntary circular muscle of rectum into distal anal canal Responsible for 85% of involuntary resting tone 2.5cm long and 2 to 5mm thick the internal sphincter terminates approximately 1cm below the dentate line Innervated by both sympathetic and parasympathetic and enteric nervus system Parasympathetic- relax - S1-3 Sympathetic alpha1- contract -hypogastric nerve The distance from the lower edge of the tumor to the upper edge of the sphincter is of critical importance in deciding the choice of surgical strategy in relation to the sphincter preservation .

47. IAS Enteric nervous system relax IAS (RAIR induced)(rectal distension ) Inherent myogenic tone Results in resting tone of IAS Residual positive pressure 60 to 85% of resting pressure

48. Conjoined longitudinal muscle Lies between IAS and EAS Extension of longitudinal rectal muscle Some of the CLM crossed EAS and insert into perianl skin (corrugator cutis) Some fiber of CLM in subepitheial space –TREITZS MUSCLE FUNCTION AS ATTACHMENT ANORETUM TO PELVIS ACRS

49. Pelvic floor muscle Levator ani- Pubococcygious ,puborectalis and iliococcygeus Levator hiatus formed by pubococcygius muscle

50. Pubo Rectalis Superior fascia of urogenital diaphragm Form a sling Ano rectal ring composed of upper border of IAS and puborectalis Contraction causes horizontal force that closes the pelvic diphgram and decrease the anorectal angle during squeeze important factor in fecal incontinence

51. Iliococcygeus muscle Lift pelvic floor

52. Pubococcygeous muscle Forms the levator hiatus Forms the hiatal ligament Enlargemnet of hiatal ligament results in female pelvic organ prolapse

53. Superficial muscle EAS Superficial transverse perineal muscle Deep transverse perineal muscle Bulbospongious muscle Ischiocavernus muscle

54. Principle of rectal surgery Wide excision to achieve negative margin Proximal Distal (1-2 cm) Circumferential(>1 mm) Adequate lymphadenectomy Number (>12) Mesorectal excision (complete or partial: 4-5 cm below the tumor ) Autonomic nerve preservation Enteric continuity / stoma

55. Resection in anus preserving surgery and anastomosis ISR: Intersphincteric resection DL: dentate line (DL) ISG: intersphincteric groove PR: peritoneal reflection LAM: levator ani muscle ES:external sphincter IS: internal sphincter ISS: intersphincteric space SbES : subcutaneous part of the external sphincter DST: double stapling technique CAA: coloanal anastomosis Akagi Y et al. Surg Today 43, 838–847 (2013) Anterior resection Colo-rectal anastomosis

56. Basis of TME TME removes the rectal cancer with its primary lymphovascular drainage as an intact package, by deliberate dissection under direct vision along embryologically determined planes between visceral and parietal structures, which preserves the autonomic nerves required for the maintenance of urinary and sexual function Sharp dissection between presacral fascia and fascia propria of rectum (visceral peritonium ) Dissection upto Levator muscle Holy plane Heald et al

57. Basis of TME Mesorectal fascia (viscera peritoneum)separate embryological origin from rectum and mesorectum(from hind gut tube ) Mesorectal fascia confers protection against tumor dissemination and confines he main route of tumor dissemination Superior recta artery lies in front visceral fascia and at as land Mark for finding posterior holy plane

58. TME principle Total exciton of mesorectum Direct vision Sharp dissection Intact fascial envelope containing tumor cells Nerve preservation of bladder and Sexual function Getting a proper CRM and distal resection margin Sphincter preservation when possible Hypogastric nerve should be visualised throughout the course

59. Separation of parietal fascia and fascia propria of rectum-holy plane

60. Low rectal cancer rectal cancer within 6cm from anal verge The distance from the lower edge of the tumor to the upper edge of the sphincter is of critical importance in deciding the choice of surgical strategy in relation to the sphincter preservation. upper edge of the sphincter is easily palpable on DRE corresponding to the muscular bundles of the puborectalis sling and levator ani musculature

61. CRM The CRM is the shortest distance between the outer edge of the tumor (whether contiguous or not) and the mesorectal fascia the lowest level of the rectum, the mesorectum disappears and the lateral resection plane corresponds to the different planes of the levator ani A positive CRM is defined as direct tumour extension (either continuous or discontinuous) or the presence of a positive lymph node within 1 mm of the radial, non‐peritonealised soft tissue edge sphincter preservation surgery is performed, the radial margin is the rectal seromuscular layer and the internal sphincter muscle. If APR surgery is performed, the radial margin is constituted of the external sphincter and the leva- tor ani

62. Tumor specific TME VS TME TME-complete removal of mesorectum Tumor specific TME(PME )–for upper rectal cancer (10 cm from anal verge )distal margin of 5cm of rectum and mesorectum, divided at same level Similar results ( Monson J R, Weiser M R, Buie W D et al. Practice parameters for the management of rectal cancer (revised)  Dis Colon Rectum.  2013;56(05):535–550. )

63. TME specimen assessment

64. Japanese 3 space and lateral pelvic lymph node dissection Tumor below 6 cm from anal verge has chance of lateral teral node involvement in- creased from 7.5 to 29.6 percenT TAKAHASHI et al

65. Summery This would make one impotent