Case 21 - CRC, Infective Diarrhoea and Diverticular Disease Flashcards
What is CRC?
More prevalent in the developed world
Most common in the recto-sigmoid junction
Most are found when they are at a late stage
Pathophysiology of CRC?
Can have a polyp that can become cancerous
Ulcer that can become malignant
Mutations lead form polyp > adenoma > carcinoma
Average of 5y difference between adenoma found and CRC
What are the genetic predispositions to CRC?
FAP Familial adenomatous polyposis Mutation in APC allele When there is a predisposition to many polyps forming in the colon Some eventually will become malignant
p53
Regulates apoptosis in cells - if there is a mutation in this then the cell will not undergo apoptosis when malignant
TSG
HNPCC
Hereditary non-polyposis
When there is a mutation in the mis-match repair mechanism gene
This means that base pair errors will not be corrected, leading to a higher likelihood of mutation and therefore malignancy
Linked with other cancers in Lynch syndrome
K-RAS
Makes missense base pair change
Proto-oncogene
RFs for CRC?
Age IBD HNPCC FAP Obesity
Symptoms of CRC?
Red flags: Abdo/rectal mass Rectal bleeding Unexplained anaemia Unexplained Weight loss FHx Change in bowel habit >60y
Screening for CRC?
Done in everyone over 55y - one off colonoscopy
At 60y offered bowel cancer stool screening every 2 years, until 75y
Differentials for CRC?
Haemorrhoids
Proctitis
IBD
Anal fissure
Investigations for CRC?
Imaging:
- Colonscopy
- Barium enema
- CT/MR virtual colonscopy
- Staging CT/PET
Staging of CRC?
T1 = in the submucosa T2 = in the muscularis T3 = in the adventitia T4 = spread to other adventitia (T4a), perforation of the bowel (T4b)
M0-1
N0-2
Dukes staging of CRC?
A = T1N0M0, T2N0M0
B=T3N0M0, T4N0M0
C= Any N1 or 2
D=Any M1
Treatment for CRC
Surgical resection
Adjuvant chemotherapy
What is a hemicolectomy?
Removal of the R colon by surgery
Will try and leave 5cm healthy bowel either side of the resection margin
What is an anterior resection?
Removal of the L colon
Try and leave 5cm healthy bowel either side of the malignancy
May have to have a defunctioning loop ileostomy
Contrast enema X-ray determines if can be anastamosed
What is an abdominoperineal resection?
Removal of part of the colon and rectum, excision of the anus
Will have to have permanent colostomy
What is rectal surgery based on staging?
T1 = surgical resection through anus T2 = resection open T3 = radiotherapy and anterior resection T4 = Lt radiotherapy, assess need for surgery
Stoma comparison
Colostomy:
- Sits in LIF
- Forms stool intermittently
- Not spouted
Ilieostomy
- Sits in RIF
- Forms liquid constantly
- Spouted
Who might have adjuvant therapy in CRC?
Dukes C may have 6 months adjuvant chemo
What is diverticular disease?
Outpouchings in the intestines due to muscle wall weaknesses
Most common in the sigmoid colon
What are symptoms of diverticular disease?
Blood in stool Constipation Bloating Fever Abdo pain
RFs for diverticular disease?
Old Constipation Low fibre diet FHx High intake of red meat
Investigations for diverticular disease?
FBC - leukocytosis
Abdo X-ray
CT - if acute abdomen
Treatment for diverticular disease
Increase fibre intake Increase hydration Analgesics Antibiotics for flare-ups Surgery if persistent flare-ups
Complications of diverticular disease
Diverticulitis
Infection of the diverticuli
Presents like appendicitis
Abscesses
Pus formation in the diverticulae - very painful
May resolve with Abx
Abscess drainage
Perforation
Can lead to faceal peritonitis
Bleeding
Occult/overt
Can use colonscopy for small bleeds
Otherwise can use angio embolisation
What is diarrhoea?
Formation of 2+ unformed stools a day
Acute <4 weeks
What is dysentry?
Blood in the stool
What can be used to treat C diff?
Vancomycin/metronidazole
History of diarrhoea?
Frequency Urgency? Stool form Stool colour Presence of blood Weight loss Recent travel New food eaten recently Occupation Animal contact Contact with ill people Anal sex
Organisms that can cause infective diarrhoea
Campylobacter E.coli Shigella Enteric fever Salmonella
How does campylobacter cause diarrhoea?
F-O transmission, from food
Most common cause of gastroenteritis
How does E. Coli cause diarrhoea?
In travellers and children
Profuse, bloody diarrhoea
How does Salmonella cause diarrhoea?
From eating reptiles/eggs
Diarrhoea, vomiting and fever
How does enteric fever cause diarrhoea?
Food and water transmission
Constipation
How does shigella cause diarrhoea?
F-O
Bloody diarrhoea
Treatment for infective diarrhoea
Often self-resolving
Fluids
Nutrition
Appropriate abx for the cause
Causes of chronic diarrhoea
Alcohol Hyperthyroidism Malaria TB Lymphoma Giardia
Organisms that can cause chronic diarrhoea
Schistosomiasis
Amoebiasis
Giardia
