Pathology of Colon Flashcards
What does the portal venous system transmit?
Deoxygenated blood from most of the GI tract and GI organs to the liver
Hepatocytes receive oxygenated blood from the
hepatic artery
The mixture of oxygenated and deoxygenated blood received by the liver filters through the
sinusoids
The portal vein is formed from
the superior mesenteric and splenic veins
Where does the portal vein lie in relation to the hepatic artery and bile duct?
Posterior
The portal vein penetrates the right border of the
lesser omentum
The porto-systemic/porto-caval anastamosis is the
collateral communication between the portal and systemic venous systems
What are the types of ano-rectal conditions?
Congenital/acquired
Local/systemic
Benign/malignant
Early/late
What are the most common presentations of ano-rectal conditions?
Pain
Haemorrhage
Dysfunction
Ano-rectal conditions can be caused by;
Inflammation
Infection
Malignancy
Trauma
Give an example of A congenital an-rectal condition
Imperforate anus
Uro-genital fistulae
Hirschprung’s Myenteric Plexus Deficiency
Give 5 examples of acquired ano-rectal conditions
Haemorrhoids Fissure Abscess Fistula-in-ano Ulceration Cancer Incontinence
What is the typical presentation of haemorrhoids?
Itching/irritation/pain around the anus
Painful bowel movements
Bleeding from anus after defaecation
What is the typical surgical treatment for haemorrhoids?
Stapled anopexy
Ultrasound guided ligation of haemorrhoids
What are the stagings of anal fissures?
Acute or chronic
At what point is an anal fissure classed as chronic
If it has been [resent for more than 6 weeks
How is an anal fissure treated?
By relaxing internal anal sphincter;
medically - topical nitric oxide, glyceryl trinitrate paste or diltiazem calcium blocker
surgically - internal lateral sphincterotomy
What is the treatment for a peri-anal abscess?
Incision and drainage
At what locations can a peri-anal abscess occur?
Submucosal
Intersphincteric
Ischiorectal
Perianal
What is the typical presentation of fistula-in-ano?
Pain and swelling around the anus and pain during bowel movements
How is a superficial fistula-in-ano treated?
Fistulotomy
How is a trans-sphincteric fistula-in-ano treated?
Seton suture, fistula plug or permacol paste
What are the causes of anal ulceration?
Crohn’s disease
Malignancy
Syphilis chancre
Nicorandil
What is the treatment for anal squamous cell carcinoma?
Radiotherapy and surgery
What is the treatment for rectal adenocarcinoma?
Neo-adjuvant chemo and radiotherapy and laparoscopic resection
Give 6 causes of constipation
Lack of fibre in diet Change in eating habits Ignoring urge to defaecate Immobility/lack of exercise Low fluid intake Anxiety/depression Antacids Antidepressants Anti-epileptics Calcium supplements Opiate painkillers Diuretics Iron supplements
What do the majority of colorectal cancers arise from?
Pre-existing polyps
What fraction of colorectal cancers are colonic and what fraction are rectal?
Two thirds colonic, one third rectal
The majority of polyps are
adenomas
What are the main histological types of polyps?
Tubular (75%)
Villous (10%)
Tubulovillous (15%)
What appearances can polyps have?
Pedunculated
Sessile
What is the basic pathogenesis of colorectal cancer from polyps?
Normal epithelium
- > small adenoma (polyp)
- > large adenoma
- > invasive adenocarcinoma
What is the typical presentation of colorectal cancer?
Persistent rectal bleeding
Altered bowel opening (particularly diarrhoea)
Iron deficiency anaemia
Palpable rectal or lower right abdominal mass
Acute colon obstruction (if stenosing tumour)
Systemic symptoms
What are the sites of colorectal cancers?
Ascending colon Transverse colon Descending colon Rectum Anus
What is the most common histological type of colorectal carcinoma?
Adenocarcinoma
What are the risk factors for developing colorectal carcinoma?
Lifestyle factors
Family history
IBD
Genetics
What is the typical presentation of right sided colorectal carcinoma?
Anaemia
Vague pain
Weakness
Obstruction
What is the typical presentation of left sided colorectal carcinoma?
Bleeding
Altered bowel habit
Obstruction
What investigations would be done to diagnose colorectal cancer?
Colonoscopy
Barium enema
CT colongraphy
CT abdomen/pelvis
What is the benefit of a colonoscopy?
Any polyps found can be removed and biopsies can be taken
What staging investigations would be doe after a diagnosis of colorectal cancer had been reached?
CT chest, abdomen and pelvis
MRI scan for rectal tumours
PET/rectal endoscopic ultrasound in selected cases
What are the treatment options for colorectal cancer?
Surgery - endoscopic if caught early enough
Stoma formation may be required
Removal of lymph nodes for histological analysis
Partial hepatectomy
Chemotherapy
Radiotherapy
