Colorectal Flashcards
What is a right hemicolectomy and when would it be performed?
The right side of the colon is removed due to disease.
The proximal resection usually starts in the terminal ileum (the full caecum is removed as it is not a good area to try and form and anastamosis to) and the distal resection margin depends on the level of disease.
An ileocolic anastamosis is then formed. This surgery is usually performed laprascopically.
What is a left hemicolectomy and when should it be performed?
Performed when there is disease such as a tumour of diverticular disease. The descending colon and sigmoid colon are both removed and an anastamosis is made (allowing for good margins)
This surgery is performed laprascopically
What is an anterior resection?
A part of the large intestine is removed via the anterior abdominal wall.
An anastomosis is always made but since the blood supply is not as good in this area passage of stool can compromise healing. For this reason a loop ileostomy can be made
What is a hartmans procedure and when is it performed?
Similar to an left hemicolectomy in that the pathology is in the sigmoid or descending colon but it is performed when the surgeon doesn’t want to make an anastamosis because of peritoneal damage or the patient is very unwell or there is a risk that the blood supply is not good enough to support an anastamosis.
The distal resection margin is closed leaving a rectal stump. The proximal resection margin in then brought through the anterior abdominal wall to make an end colostomy.
There is a possibility that the colostomy then be rejoined onto to their rectal stump at a later date (reversal of hartmans procedure)
Hartmans - ALWAYS a rectal stump and ALWAYS an end colostomy formation
What is abdomino - perineal (AP) resection and when is it used?
Performed if the pathology is in the low rectum or anus. The anus is excised completely and the proximal resection margin is brought out to the anterior abdominal wall to form a permanent end colostomy.
Where are the locations of colorectal cancer?
Rectal (40%) Sigmoid (30%) Descending colon (5%) Transverse colon (10%) Ascending colon and caecum (15%)
What is the screening for colorectal cancer?
Men and women are sent FOB tests in the post every 2 years from 50 - 74.
What do most colorectal cancers develop from?
An adenomatous polyp
What two genetic conditions can cause colorectal cancer?
HNPCC (5%)
Familial adenomatous polyposis
What is HNPCC?
Hereditary non-polyposis colorectal carcinoma.
Autosomal dominant condition where you develop poorly differentiated and highly aggressive bowel cancer, unusually of the proximal colon. This is due to mutations causing microsatellite instability. The genes involved are MSH2 and MLH1. They are also at risk of other cancers such as endometrial cancer. There is a criteria than aids diagnosis
1. At least three family members with colon cancer
2. Cases span at least 2 generations
3. At least one case diagnosed before 50.
What is familial adenomatous polyposis ( FAP)?
A rare autosomal dominant conditions that leads to the formation of hundreds of polyps by age 30 - 40. It is due to a mutation in a tumour supressor gene APC on chromosome 4. Patients generally have a total colectomy ith an ileo anal pouch in their 20s
How does an anal fissure present?
Bright red rectal bleeding that occurs after defecation in small volumes but is very painful.
How do haemorroids present?
Bright red rectal bleeding after defecation. Not painful. History of straining
What investigations are required in every patient with rectal bleeding?
PR exam
Sigmoidoscopy
In patients with altered bowel habit a colonoscopy is needed.
Where is the colon are diverticuli most often found?
Sigmoid and descending colon (less common in the right hand side)
Why are diverticuli a false diverticuli but meckels diverticuli is a true diverticuli?
Diverticuli are an outpouching of mucosa without a muscle coat whereas a meckels diverticuli also has the normal bowel muscle coat
What is acute diverticulitis and how does it present?
An infection of one or more diverticuli causing inflammation. This can cause:
- Perforation into te peritoneum, pericolin tissues or adjacent structures
- Chronic infection with fibrosis resulting in obstruction
- Haemorrhage as a result of erosion of a vessel into the bowel wall
Present with low central abdominal pain that w switches to the LIF accompinied by fever, vomiting, local tenderneess and guarding.
How does chronic diverticular disease present?
- Change in bowel habit
- Large bowel obstruction
- Blood and mucus per rectum
Examination reveals tenderness in the LIF and possibly a mass
What investigations do you do if you suspect diverticulitis?
CT (also helps diagnose other differentials) Sigmoidoscopy/colonoscopy Barium enema (globular outpouchings with a signet ring appearance) Barium eneme is not done in the acute setting as it can cause perforation and a leak of barium.
How do you differentiate diverticulitis from colorectal cancer?
You need a biospy as they present in a very similar manner and look similar of colonoscopy.
How do you treat acute diverticulitis?
- Fluid diet
- Antibiotics (Amox + Met + Gent)
- Abscesses should be drained.
- Perforation or obstruction need to be taken to theatre for a laparotomy and usually result in a hartmans procedure with the affected part of the bowel being resected.
How is chronic diverticular disease treated?
Mild: Laxative such as lactulose and high fibre diet
Severe: Laparotomy and resection
What is angiodysplasia?
One or more small mucosal or submucosal valvular malformations, usually a dilated vein or sheaf of veins. They occur most common in elderly people and are considered to be a degenerative change .
How does angiodysplasia present?
Bleeding - can be either continous or bright red rectal haemoorhage
What investigations do you do if you suspect angiodysplasia?
Colonoscopy (lesions are bright red submucosal lesions with small dilated vessels and are about 0.5 - 1cm)
Mesenteric angiogram detects actively bleeding angiodysplasia
