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surgical anatomy of rectum
1. Surgical anatomy of the
rectum-anatomical basis of
resections
Presenter-Yajnadatta Sarangi
Moderator-Dr Ashok Kumar sir
2. Embryology
• Rectum and proximal 2/3rd 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 rectum
• Anatomist –Dentate line
• Radiologist-Anal 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 (the level of puborectalis sling
)
• Anorectal junction in male corresponds to apex of prostate
4cm in front of tip of coccyx
• The dentate line demarcates the superior two-thirds of the
anal canal from the inferior one-third.
• the 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 11 cm-most
common site of rectal cancer
• Upper (proximal) rectal cancers 12 to 15
cm
• The anal canal is 0 to 4 cm from the anal
verge
New Insights into the Surgical Anatomy of the
Rectum: A Review
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 1/3rd of
rectum
• Middle rectal fold corresponds 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 al, 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.
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 Kulaylat MN.World J Surg Proced 2015
17. Denonvillier’s fascia
• Dissection 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. Rectosacral fascia or Waldeyer's fascia
• Dense connective tissue attaching the posterior wall of the rectum to presacral fascia
at the third and fourth sacral vertebra.
• Failure 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 divided
• blunt hand dissection of waldeyers fascia may cause avulsion injury of the presacral
fascia
• Sharp 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
26. Lymphatics of Rectum
• 2 Group –intramural and extramural
• Lymph from the upper third of the rectum, drains to superior rectal
nodes after transversing para- rectal nodes. then to inferior
mesenteric nodes.
• Lower 1/3rd 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 mucocutaneous
junction is exceptional to superficial inguinal node
• 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
Most 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.
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”
• Prevented 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
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.
• upper 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.
48. 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
49. 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
50. Pelvic floor
muscle
• Levator ani- Pubococcygious
,puborectalis and iliococcygeus
• Levator hiatus formed by
pubococcygius muscle
51. 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
53. Pubococcygeous muscle
• Forms the levator hiatus
• Forms the hiatal ligament
• Enlargemnet of hiatal ligament results in female pelvic organ prolapse
55. 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
56. 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
57. 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
58. 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
59. 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
61. 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
62. 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
63. 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. )
65. 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
66. • Tumor extending less than 1 cm from
dentate line (T3–T4 cancer)
• Tumor-threatening CRM
Extralevator APE
• Locally advanced cancer infiltrating levator
muscles, ischioanal fat or perianal skin
• Perforated cancer with abscess or fistula in
ischioanal compartment
Ischioanal APE
