Large intestine
Blood supply:
-
Blood supply of the caecum to the splenic flecture is from the Superior mesenteric artery ( iliocolic , right and middle colic arteries )
Blood supply of the descending colon and sigmoid is from branches of the inferior mesenteric
artery ( left colic and sigmoid arteries )
Functions of the Colon:
1. Water absorption.
2. Salt Absorption (NaCl).
3. Bacterial Metabolism and fermentation.
4. Storage and evacuation of feces.
Congenital megacolon (Hirschsprung’s disease)
Pathology:
Absence of ganglion cells in the neural plexus of the intestinal wall, together with hypertrophy of the
nerve trunks.
The loss extends for a variable distance above the ano-rectal junction. The severity of symptoms is not
always consistent with the length of segment involved.
The absence of ganglion cells gives rise to a contracted non peristaltic segment with proximal dilated
hypertrophied segments of normal colon.
Clinical Features:
1. 1/5000 live births.
2. Familial tendency
3. Common in males than in females.
4. 10% associated with Down syndrome.
Clinical picture varies from acute intestinal obstruction in neonates to chronic constipation in later life:
A. in neonates there will be delayed passage of muconium, abdominal distention following feeds and
bilious vomiting and often complicated by enterocolitis leading to perforation and septicemia.
B. chronic constipation starting in the first few weeks of life will be manifested as gross abdominal
distention and failure to thrive.
C. Sever constipation without soiling in otherwise healthy children can be caused by a short segment of
the disease.
Diagnosis:
1. Full thickness rectal biopsy (in adult), suction rectal biopsy (in children).
Specimens are taken from just above the ano-rectal junction.
2. Ano-rectal manometry. (In this case the recto-sphincteric inhibitory reflex is absent)
3. Radiology (Erect abdominal radiographs showing distended loops of intestine with fluid levels)
An enema using a water soluble contrast medium will confirm the diagnosis and indicate the length and
site of the involved intestine.
Treatment:
The treatment depends on the age of the patient, the length of the involved segment, the severity of
symptoms and the presence of entero-colitis.
1. Neonates presented with obstruction or any child, or adult presented with enterocolitis – an initial
colostomy is performed with per-operative frozen section biopsy is taken to establish the presence of
ganglia.
2. In the child or adult with constipation alone, the dilated intestine can be evacuated with repeated
rectal saline washout and enemas as a first step.
The choice of surgical procedures to follow will depend on the length of the involved segment.
If it is a Short segment with minimal symptoms then an extended myectomy (removing a strip of rectal
wall) is done.
If it is a Long segment disease then a temporary colostomy for few months to allow proximal distended
colon to return to normal.
Definitive surgery when the child weight becomes 10 Kg and the child will be between 10 months and 1
year of age and the choice of surgery will be either Duhamel operation, Swenson’s operation, colo-anal
anastamosis or restorative procto-colectomy.
Vascular Anomalies (Angiodysplasia):
It is a vascular malformation associated with aging that occurs particularly in the ascending colon and
caecum of elderly patients.
It consists of dilated tortuous sub mucosal veins and on histological studies it is made up of dilated
distorted thin walled vessels with only scanty amount of muscle in their walls.
By endoscopy the lesions are only few millimeters in size and appear as reddish, raised areas.
Bleeding is usually chronic and intermittent.
Barium enema is usually unhealthful and should be avoided.
Selective superior and inferior mesenteric angiography shows the site and extent of the lesion.
If this fails, a radioactive test using Technetium 99m labeled red cells may confirm and localize the
source of hemorrhage.
Treatment:
Some lesions can be treated by colonoscopic diathermy but if the bleeding is brisk and the patient is
seriously ill then emergency surgery will be necessary.
On table colonoscopy is done and the site of the bleeding can be confirmed.
If it is still not clear exactly which segment of the colon is involved then a total abdominal colectomy
with ilio rectal anastamosis may be necessary.
Diverticular disease of the colon:
Diverticula of the colon are acquired herniations of the colonic mucosa protruding through the circular
muscles at the points where the blood vessels penetrate the colonic wall.
Most commonly found in the sigmoid colon but the caecum can also be involved and on occasion the
entire large bowel can be affected.
The rectum with its complete muscle layers is not affected.
In 90% of cases the sigmoid colon is involved and it is almost always the site of inflammation
(Diverticulitis)
5% of patients have associated gallstones and hiatus hernia (Saint’s triad).
Diverticulosis: It is the presence of Diverticula without symptoms.
Diverticula arise as a result of muscular coordination and spasm resulting in increase segmentation and
intraluminal pressure.
The diverticulum consists of a protrusion of mucous membrane covered with peritoneum and there is
thickening of the circular muscle fibers which develop as concertina or saw-tooth appearance on barium
enema.
The Diverticula occur between the muscles clefts making the mucosal surface appear trabeculated.
Diverticulitis: It is the inflammation of one or more Diverticula with some pericolitis.
Episodes of diverticulitis may be followed by years free of symptoms but the condition is progressive, it
may be complicated by:
1. Recurrent periodic inflammation and pain.
2. Perforation leading to peritonitis or local (Pericolic) abscess formation.
3. Intestinal obstruction in the sigmoid due to progressive fibrosis causing stenosis.
4. Diverticulitis may present with profuse colonic hemorrhage in 17% of cases.
5. Fistula formation 5% (vesico colic, vagino colic, enterocolic, colo cutaneous).
Clinical features:
1. Diverticulosis may be asymptomatic.
2. Disordered colonic function may cause symptoms of distention, flatulence and sensation of heaviness
in the lower abdomen. (Similar to IBS)
3. Exessive colonic segmentation can cause severs pain in the left iliac fossa but this must be
distinguished from episodes of mild diverticulitis.
Persistent lower abdominal pain, usually in the left iliac fossa in patients of either sex over the age of
40yrs could be caused by diverticulitis.
4. Fever, Malaise and lucocytosis can differentiate diverticulitis from painful Diverticulosis.
5. The patient may pass loose stool or may be constipated.
6. Tenderness of the lower abdomen especially on the left iliac fossa.
7. Sigmoid is often palpable, tender and thickened.
8. Rectal examination may reveal a tender mass (left sided appendicitis).
9. In vesico-colic fistula there are urinary symptoms and pneumaturia and even feces in the urine.
Diagnosis:
Radiology
Diverticulosis is a diagnosis of exclusion of other diseases by barium enema, sigmoidoscopy or
colonoscopy.
Acute diverticulitis can be confirmed during the acute phase by CT (Showing Diverticula and Pericolic
abscess).
Barium enema and sigmoidoscopy are usually delayed after recovery from acute attack.
Barium enema is carried out to exclude carcinoma and to assess the extent of the disease; it may show a
saw tooth appearance or strictures.
Visco-colic fistula should be evaluated with cystoscopy, colonoscopy and biopsy.
Plain abdominal x-ray may show gas in the bladder.
Colonoscopy or flexible sigmoidoscopy may be used for diagnosis for acute diverticulitis
Management:
Medical management;
Diverticulosis – *high residue diet in the form of whole meal bread, flour, fruit and vegetables.
*Bulk formers (Bran,celevac , isogel and fybogel )
*Antispasmodics and bed rest for painful Diverticular disease.
*Acute diverticulitis – Bed rest, IV antibiotics (Cefuroxime and Metronidazole).
Operative procedures for Diverticular disease;
10% of patients require operation for recurrent attacks or for the complications of diverticulitis:
1. One stage resection (excision of the affected segment and restoration of continuity )
2. If there is obstruction, edema, adhesions or the bowl is loaded with feces – Hartmann’s procedures
after excision of the affected segment.
3. In acute perforation with peritonitis we can either do:
A- Primary resection and Hartmann’s procedure.
B-Primary resection and anastamosis after on table lavage.
C-Exteriorisation of the affected bowl which is then opened as colostomy (rare).
D- Suture of the perforation with drainage with or without proximal defunction.
4. Treatment of fistula is by resection of the diseased bowl and closure of the fistula.
In colo-vasical fistula – isolate the bowl from the bladder, suture the bladder and resect the sigmoid
segment.
5. Hemorrhage from diverticulitis usually response to conservative management and occasionally
requires resection.
Ulcerative colitis:
-Unknown etiology
-Familial predisposition
-No infective organism could be incriminated
-Smoking has a protective effect.
-Stress might lead to relapses
-10 to 15 new cases per 100000 populations in the UK.
-It was rare in eastern population however the incidence is increasing.
-Sex ratio is equal
-Uncommon before the age of 10, mostly between 20 and 40 yrs of age.
Pathology:
95 % of cases starts in the rectum and separates proximally.
It is a non specific inflammatory disease, primarily affecting the mucosa and sub mucosa and very rarely
the deeper layers of wall.
There are multiple minute ulcers.
In chronic disease, inflammatory polyps (pseudo polyps) occur in up to 20% of cases. They result from
previous ulcerations leaving islands of spared mucosa which will remain prominent when the adjacent
mucosa heals.
In sever fulminant colitis, transverse colon may become acutely dilated with thin wall and may perforate
(Toxic mega colon)
Microscopic examination – Increase inflammatory cells in the lamina propria
-- Infiltration of walls of crypts by inflammatory cells.
-- Depletion of goblet cell mucin.
-- With time these changes become sever leading to dysplasia or carcinoma in
situ.
Symptoms:
1. Watery or bloody diarrhea with rectal discharge of mucous (blood stained or purulent).
2. Chronic disease with relapses and remissions.
3. Poor prognosis is indicated by sever initial attacks, sever disease involving the whole colon and
increasing age.
Proctitis: - Disease confined to the rectum (25%) , stool is formed or semi-formed , sever tenesmus.
Left sided and total colitis: - (15% have left colitis and 25% have total colitis), recurrent sever attacks of
bloody diarrhea, dehydration and fluid / electrolytes losses, anemia and hypoproteinemia are common.
Disease severity:
1. Mild – rectal bleeding or diarrhea with 4 or fewer motions per day and absence of systemic signs of
the disease.
2. Moderate - More than 4 motions per day but no systemic signs.
3. Sever – More than 4 motions per day with one or more signs of systemic illness (Fever, Tachycardia,
Hypoalbuminemia and weight)
Complications of Sever disease:
1. Fulminating colitis and Toxic mega colon – sever abdominal pain, huge dilatation of the colon,
progressive increase in the diameter inspite of medical therapy.
2. Perforation
3. Sever hemorrhage
Investigations:
Plain x-ray of the abdomen - we will find Dilated colon, feces are present only in parts of the colon that
are normal, small bowl loops located in the right lower abdomen.
Barium enema – * Loss of hostration
* Granular mucosa
* Pseudo polyps
* Narrow contracted colon (in chronic disease / led pipe appearance)
Sigmoidoscopy – signs of Proctitis (Hyperemic mucosa bleeds on touch and pus like exudates).
Tiny ulcers are late signs.
Colonoscopy & Biopsy – used to establish the extent of the disease, differentiate between ulcerative
colitis and Crohn’s colitis, monitor response to treatment, and assess chronic cases for malignant
changes.
Extra-Intestinal manifestation of Ulcerative Colitis:
1. Arthritis of large joints.
2. sacro-iliitis and ankylosing spondylitis.
3. Bile duct cancer.
4. Skin lesions, erythema nodosum, and pyoderma gangrenosum or aphthous ulceration.
5. Iritis.
6. Sclerosing colingitis.
Treatment:
Mild attacks –
1. Rectally administered steroids for mild attacks and oral prednisolon 20-40 mg per day for more
extensive disease for 3 to 4 weeks.
2. Sulphasalazine 1 gm, 3 times daily should be given also.
Moderate attacks –
1. Oral prednisolon 40 mg per day.
2. Twice daily steroid enemas and 5 ASA (5 amino Salicylic acid).
Sever attacks –
1. Admission to the hospital.
2. Frequent measurement of abdominal girth.
3. Daily abdominal x-ray for follow of dilatation of the transverse colon of more than 5.5 cm.
The presence of mucosal islands, increasing colonic diameter or a sudden increase in pulse or
temperature may indicate colonic perforation.
4. Stool chart to help assessment of response to therapy.
5. Maintanance of fluid and electrolytes, correction of anemia and nutritional deficiency, nothing by
mouth, IV hydro cortisone 100-200 mg 4 times daily.
6. Rectal infusion of hydrocortisone.
7. Sometimes Azathioprene or cyclosporine A.
8. Failure of treatment within 5-7 days – consider surgery.
Indications for surgery:
1. Sever fulminating disease failing to response to medical therapy.
2. Chronic disease with anemia, frequent stools, urgency and tenesmus.
3. Steroid dependant disease.
4. Risk of neoplastic change.
5. Extra-intestinal manifestations.
6. Sever hemorrhage or obstruction.
Types of operations:
1. Proctocolectomy and permanent Iliostomy.
2. Restorative Procto-colectomy with ilio-anal pouch.
3. Colectomy and ilio-rectal anastamosis.
4. Iliostomy with a continent intra-abdominal pouch (Kock’s Procedure).
Crohn’s Disease of the Colon:
Tumors of the Large Intestine:
1. Benign Tumors (Polyps):
Polyp: is any elevated tumor that can occur single or multiple.
A- Adenomatous polyps:
-Vary from a tubular adenoma (raspberry on a stock) to the villous adenoma (flat spreading lesions)
-Solitary adenomas are usually symptomless while villous adenomas usually give symptoms of diarrhea,
mucous discharge and occasionally hypokalaemia.
-The risk of malignancy of adenoma increases with increasing size of adenoma.
-Adenomas of larger than 5 mm should be treated because of their malignant potential.
-Colonoscopic snare polypectomy or diathermy obliteration with biopsy forceps can be used.
-Huge villous adenoma on the contrary might require resection of the part of the large bowl involved ( in
the rectum – proctectomy ) .
B-Hamartomatous polyps:
Peutz-Jeghers polyps may occur in the colon as single or multiple.
Juvenile polyps may occur as multiple lesions in the colon.
They have minimal malignant potential, they must be removed only if they’re causing symptoms (Pain,
bleeding).
C-Hemangioma:
A localized sub mucous telangiectasis that often cause bleeding.
Diagnosis is by angiography and colonoscopy and it can be removed by endoscopy or injection of
vasopressin or microspheres to stop the hemorrhage.
D- Lipoma:
It is rare in the large bowl, usually in the caecum. It is sub mucous and might cause intussusception/
E- Familial Adenomatous polyposis (FAP):
It is a general neoplastic disorder of the intestine mostly affecting large bowl but it can occur in the
stomach, duodenum and small intestine.
The main risk is large bowl cancer.
Inherited as autosomal dominant (APC gene) on the short arm of chromosome 5.
Male and females are equally affected.
It is associated with benign mesodermal tumors (desmoids and osteomas)
Clinical features:
Loose stool, lower abdominal pain, weight loss, diarrhea and passage of blood and mucous.
Diagnosis: by sigmoidoscopy or double contrast barium enema.
If over 100 adenomas (Polyp) are present, the diagnosis can be made confidently.
Members of affected families should attend for screening sigmoidoscopy.
If there are no adenomas by the age of 30 then FAP is unlikely to occur in that person.
If the diagnosis is made during adolescence, operation is postponed to the age of 17 or 18.
Screening policy:
1. All members of the family should be examined at the age of 10 to 12 years, repeated every 1 to 2
years.
2. Most of those whom are going to get polyps will have them at the age of 20 yrs and those would
require operations.
Treatment:
Colectomy with ilio-rectal anastamosis was the procedure of choice and the rectum is subsequently
cleared of polyps by snaring or fulguration.
Inspite of this, a proportion of patients develop carcinoma in the rectal stump.
Alternatively a restorative procto-colectomy with an ilio-anal anastamosis is used now.
2. Malignant tumors of large intestine
Usually adenocarcinoma of columnar type
The tumor may take one of four types: annular, tubular, cauliflower, or ulcerative type.
The annular type mostly gives rise to obstructive symptoms while other types present with bleeding.
Large intestine tumors are more common in the rectum and left colon.

Spread of tumors
Usually slow growing tumors spread either
Local: where it is limited to the bowel wall for considerable time and it spreads round the
intestinal wall and usually causes intestinal obstruction before it invades local structures. The
ulcerative type more commonly invades locally and may lead to internal fistula. There may be
also local perforation leading to abscess or peritonitis or external fecal fistula.
Lymphatic spread:
N1: nodes in the immediate vicinity of the bowel wall.
N2: nodes along ileocolic, right colic, middle colic, left colic and sigmoid arteries.
N3: nodes around superior and inferior mesenteric trunks.
Blood stream metastasis
Via the portal system to the liver. it accounts for 30-40% of late death . Sometimes it appears
before local or lymphatic metastasis (occult hepatic metastasis).
*Staging of colon cancer
Duke’s classification:
A: confined to bowel wall
B: through the bowl wall but not involving the free peritoneal serosal surface.
C: Lymph nodes involved.
D: advanced local disease or liver metastasis.
The TNM classification is more detailed.
T1: into sub mucosa
T2: into muscularis propria
T3: into Pericolic fat but not breaching serosa
T4: Breaches serosa or directly involving another organ.
N0: No nodes involved
N1: one or two nodes involved
N2: three or more lymph nodes involved
M0: No distant metastasis
M1: distant metastasis
Clinical Features:
Usually occurs over 50 years of age.
20 % present as emergency with intestinal obstruction and peritonitis.
The most common symptoms are:
1. Alteration in bowl habit.
2. Rectal bleeding and/or mucous.
3. Abdominal pain (colicky or fixed).
4. Weight loss.
5. Tenesmus and malaise.
Carcinoma of the left side of the colon:
Most tumors occur in this location and they are usually of the stenosing type.
The main symptoms are those of increasing intestinal obstruction (pain, alteration of bowl habit,
palpable lump and distention)
Carcinoma of the sigmoid:
Symptoms are similar to the left colon with some differences.
1. The pain is usually colicky since the beginning
2. Tenesmus.
3. Bladder symptoms.
Carcinoma of the transverse colon gives rise to the epigastric pain, sometimes palpable mass with
anemia and lassitude.
Carcinoma of the caecum and ascending colon:
1. Severe anemia not responding to treatment with sometimes palpable tumor.
2. Mass in the right iliac fossa.
3. Incidental finding during appendicectomy.
4. Ca caecum can be the apex of an intussusception presenting with symptoms of intermittent
obstruction.
Metastatic disease patients may present for the first time with liver metastasis, enlarged liver, ascites or
rarely metastasis to the lung, bone and brain.
Physical findings (Signs):
Palpable mass from the abdomen or on a rectal examination, sever anemia, weight loss or signs of bowl
obstruction.
Investigations:
1. Rigid or flexible sigmoidoscopy should be done for every patient with rectal bleeding.
2. Colonoscopy for direct examination of the tumor and to take biopsy from the tumor and to detect
synchronous polyp or even multiple carcinomas (5 %).
3. Radiology:
Double contrast barium enema showing cancer as a constant irregular filling defect, it should be done
for every patient with change of bowl habit or bleeding.
Ultrasonography of the abdomen used as a screening investigation for liver metastasis.
CT scan is used in patients with large palpable abdominal mass to determine local invasion and it is
particularly used in the pelvis in the assessment in the rectal cancer.
Treatment:
Pre-operative preparation:
1. Mechanical bowl preparation:
2. Oral laxative
3. Whole gut irritation.
4. Enema/colonic irrigation.
5. Antibiotic chemoprophylaxis.
6. Thromboembolism prophylaxis
7. Correct anemia.
8. Correct electrolyte deficiencies.
Operations:
-
Carcinoma of the caecum – right hemicolectomy
-
Carcinoma of the hepatic flexure – extended right hemicolectomy
-
Carcinoma of the transverse colon – excision of the transverse colon and the two flexures with
the transverse meso-colon and greater omentum.
-
Carcinoma of the splenic flexure or descending colon – left hemicolectomy
-
Carcinoma of the pelvic colon – left hemicolectomy
* When a growth is found to be inoperable – proximal colostomy or if the tumor is in the ascending
colon – a bypass using an ileocolic anastamosis is the best procedure.
* For hepatic metastasis – hepatic resection is usually performed as a staged procedure.
* Adjuvant therapy should be given for patients with Ca colon.
Rectal Carcinoma:
Is usually presented with rectal bleeding, tenesmus, signs and symptoms of obstruction.
A tumor in the mid or upper rectum is removed by anterior resection with end to end anastamosis of
the colon and the lower third rectum.
A low rectal tumor required removal of the whole rectum and adjacent sphincters (abdomino-perineal
resection) with end colostomy.