The Rectum
Anatomy:
Five inches long. Begins at the sacral promontory and ends at the
ano-rectal junction. The puborectalis muscle encircles the posterior
and lateral aspects of the junction creating an angle of 120 degrees.
The rectum has 3 curvatures, upper and lower convex to the right
and the middle convex to the left. On the luminal surface these
curves are marked by semilunar folds( Huoston valves ). Lower third
of the rectum is separated from the prostate/ vagina by
Denonvillier’s fascia and from the sacrum and coccyx by the
Waldayer’s fascia. These are important surgically as they are
barriers for cancer spread.
Blood supply: superior, middle and inferior rectal arteries.
Lymphatic drainage: Although follows the blood supply, the principal
route is upward along the superior rectal vessels to the para-aortic
lymph nodes.
Main symptoms of rectal disease:
Bleeding per-rectum
Altered bowel motion
Mucous discharge
Tenesmus
Prolapse
Rectal injuries: Mechanisms:
1. Falling in a sitting position on a pointed
object.
2. Penetrating injuries, gun or stab, to the
buttocks.
3. Sexual activity or assault.
4. Fetal head during child birth, especially
forceps-assisted.
Investigations:
Water-soluble contrast enema with X ray or CT
scan.
Treatment:
1. Examination under anesthesia.
2. Temporary colostomy is often necessary.
3. There is serious risk of necrorizing fasciitis
and broad-spectrum antibiotics are mandatory.
4. There may associated bladder or urethral
injuries.
Rectal Prolapse:
May be mucosal or full thickness
In full thickness, the whole rectal wall is involved
It commences as a rectal intussusception
In children, prolapse is usually mucosal and should be
treated conservatively
In adults the prolapse is full thickness and associated with
incontinence
Surgery is necessary for the full thickness and performed
either via the perineum or abdomen
Mucosal prolapse:
In infants: Due to the direct downward course of the
rectum due to the under-developed sacral curve and
low resting anal tone.
In children: Commences after an acute attack of
diarrhea or from loss of weight and consequently loss
of fat of the ischio-rectal fossa.
In adults: causes:
3
rd
degree hemorrhoids
Perineal tear in females
Straining due to urethral stricture
Operation for anal fistula
# Prolapse mucous membrane is pink while prolapse
internal hemorrhoids are plumb.
Treatment:
I. In infants and children:
1. Digital repositioning.
2. Sub-mucosal injection: If digital repositioning fails after 6
weeks and is carried out under GA and using 5% phenol in
almond oil.
3. Surgery: Occasionally required. In this case, the child is
placed in the prone jack-knife position, retro-rectal space is
II. In adults:
1. Local treatment: Sub-mucosal injection or rubber banding.
2. Excision of prolapsed mucosa.
rectum sutured to the sacrum.
Full thickness prolapse ( Procidentia):
Less common than the mucosal variety. Consists of all the layers of the rectal
wall and associated with a weak pelvic floor. Thought to commence as an
intussusception of the rectum. Any prolapse > 5cm in length contains between
its layers a pouch of peritoneum. The anal sphinctor is patulous and gapes
wisely on straining. More common in the elderly and MF ratio 1: 6. Commonly
associated with uterine prolapse.
Differential diagnosis: Intussusception. This is differentiated by the presence of
a deep groove between the protruding mass and the anal margin.
Treatment:
Is surgical by the perineal or abdominal approach. Abdominal recto-pexy has a
lower recurrence rate but when the patient is elderly, a perineal approach
under spinal anesthesia is usually safer. Also the abdominal approach has the
risk of damage to the autonomic nerves resulting in sexual dysfunction which
makes perineal approach preferred in young men.
Perineal approach:
Thiersch: Became obsolete.
Delorme operation
Altemier operation
Abdominal approach: Fixing the rectum to the sacrum by many ways eg.
interrupted non-absorbable sutures, Teflon sling or poly-prolene mesh.
Tumors of the rectum:
I. Benign:
1. Adenoma 2. Hemangioma 3. Lipoma 4.Neurogenic tumors 5.GIST
II. Malignant: Carcinoma:
Overall, colorectal cancer is the 2
nd
most common malignancy in the Western
countries and the rectum is the most commonly-involved site.
Origin: Adenoma-carcinoma sequence. In 5%, there is more than one
carcinoma site.
Macroscopically: 1. Ulcer ( most common) 2. Polyp 3. Infiltrating
Spread:
1. Local: circumferential rather than longitudinal. After the muscle coat had
been penetrated, the growth spreads into the surrounding meso-rectal fascia. If
penetration occurs anteriorly, the prostate, seminal vesicles and the bladder
become in males and the vagina and uterus in females. In both sexes lateral
spread involves the ureters and posterior spread involves the sacrum and sacral
plexus. Downward spread more than few centimeters is rare.
2. Lymphatic: Above the peritoneal reflection occurs almost exclusively upward;
below that level spread is still upward but when in the region of the middle
rectal artery, lateral spread might happen. Downward spread is exceptional
along the subcutaneous lymphatics to the groin, limited to the lymphatics
draining the perianal rosette and the epithelium of the distal 1-2 cm of the anal
canal.
3. Hematogenous: Liver, lungs and adrenals
4. Trans-peritoneal
Staging:
TNM
Dukes:
A Confined to the rectal wall
B Extends to the extra-rectal tissues
C Involving lymph nodes:
C1: Para-rectal
C2: Lymph nodes accompanying supplying blood vessels
D ‘ not described by Dukes’ signifies distant metastasis, usually
hepatic.
Grading:
Low grade: Well-differentiated, good prognosis.
Average grade: Moderately-differentiated, fair prognosis.
High grade: Poorly-differentiated, poor prognosis.
In a small proportion, the tumor is a primary mucoid carcinoma.
The mucous lies within the cells, displacing the nucleus to the
periphery, like the seal of a signet ring. Prognosis of this type is very
bad.
Clinical features:
Most common after the age of 55yrs.
1. Bleeding per-rectum is the earliest and most common.
2. Tenesmus.
3. Alteration of bowel habit.:
Annular carcinoma at the recto-sigmoid junction causes
constipation.
Carcinoma of the rectal ampulla causes early morning
bloody diarrhea.
4. Pain: Causes:
1. Intestinal obstruction
2. Prostate and seminal vesicles involvement
3. Backache and sciatica occurs when cancer invades
the sacral plexus
5. Weight loss: Suggestive of hepatic involvement.
Diagnosis and assessment of rectal cancer:
All patients with suspected rectal cancer should
undergo:
*Digital rectal examination
*Sigmoidoscopy and biopsy
* Colonoscopy if possible or CT colonography or
barium enema
All patients with proven rectal cancer require staging
by:
Imaging of the liver and chest, preferably by CT
Local pelvic imaging by MRI and/or endo-luminal
ultrasound
Treatment:
Surgery remains the main treatment option but before
it, it is necessary to assess:
Fitness for GA
Extent of tumor spread
Principles of surgical treatment:
Radical rectal excision
TME: Total meso-rectal excision
Lymphatic excision: High ligation of the lympho-
vascular pedicle which is the inferior mesenteric artery.
Operative options:
1. Local procedures: Trans-anal excision and TEM
( Trans-anal endoscopic microsurgery)
These can be used for:
Unfit patients
Early tumors
Distant metastasis
2. Anterior resection:: When rectal excision is possible,
the aim should be to restore GIT continuity and
continence by preserving the anal sphincter whenever
possible. This operation is usually possible for tumors
whose lower margin is > 2cm above the anal canal and
it can be performed by open or laparoscopic approach.
3. Hartmann’s operation
4. Abdomino-perineal excision of the rectum.
Traditionally performed by two surgeons. Needed for
tumors of the lower 1/3 of the rectum that are
unsuitable for anterior resection.
Pre-operative preparation:
Stoma counseling and siting
Correction of anemia and electrolyte disturbance
Blood cross matching
Bowel preparation
DVT thrombo-prophylaxis
Prophylactic antibiotics
Insretion of a urinary catheter
5. Endoluminal stenting
6. Palliative colostomy
7. Other palliative procedures eg. Nd-YAG LASER can be
used for obstruction or bleeding
8. Liver resection
9. Radiotherapy: Neoadjuvant can make resection
possible for some un-resectable tumors
10. Chemotherapy: 5FU is the most frequently-used.
Giving it through the portal vein after the primary
operation has shown a small benefit. Neoadjuvant
( preoperative) chemotherapy over 6 weeks may reduce
the tumor size and make curative surgery possible.