Large Colon and Rectum Flashcards
Describe the anatomical difference between Crohn’s and Ulcerative Colitis.
Crohn’s is mouth to anus.
UC is colon and rectum only.
Describe the pathological difference between Crohn’s and UC.
Crohn’s -> granulomas and skip lesions (+ deep ulceration, cobblestoning, cryptitis, pseudopolyps)
UC -> Superficial irregular crypts. Basal lymphoplasmocytic infiltrate
Name the genetic causes of Crohn’s and UC.
Crohn’s -> chromosome 16 -> HLA-DR1, HLA-DQw5
UC -> NOD-2, HLA-DR2
What are the presenting complaints of Crohn’s and UC?
Crohn’s -> abdo pain, perianal disease, diarrhoea
UC -> abdo pain, diarrhoea/blood, pus/mucus
Describe the lymphocytes involved in Crohn’s and UC.
Crohn’s -> TH1
UC -> TH1/TH2/NKTC
Describe the role of smoking and NSAIDs in Crohn’s and UC/
Crohn’s -> both bad
UC -> smoking is good, NSAIDs bad
Which investigations should be used in Crohn’s?
Ba follow through, MRI, technectium WBC scan
Which investigations should be used in UC?
CRP/albumin, AXR, endoscopy, histology
Describe the Truelove/Witt criteria for UC.
> 6 bloody stools in 24 hours, + fever, tachycardia, anaemia, increased ESR
Name and describe the drug treatments for Crohn’s and UC.
Steroids (short course 6-8 wks) Immunosuppressants (maintenance C/steroid-saving UC) Anti-TNF therapy 5ASA therapy (UC) Biosimilars
Describe IBS.
Irritable bowel syndrome - a functional GI disorder.
What are the Rome III criteria used to diagnose IBS?
Recurrent abdo pain/discomfort + 2 of - improvement with defecation - change of frequency of stool - change of appearance of stool For 3 days/month for 3 months
What are the six Manning criteria for IBS?
- pain relief on defecation
- more frequent stools
- visible abdo distension
- passage of mucus
- looser stools
- sense of incomplete evacuation
What are the red flag symptoms for IBS?
Weight loss, blood in stool, anaemia, fever, history of progressive pain
Which are the risks for IBS?
<45, female, family history, mental health problems
What are the three types of IBS?
IBS-C (constipation), IBS-D (diarrhoea), IBS-M (mixed)
What should be used to treat IBS-C?
Diet (more fruit and veg) Short term antispasmodics Fibre Osmotic laxatives 5-HT4 antagonists
What should be used to treat IBS-D?
Diet (avoid fruit/veg - FODMAP diet) Short term antispasmodics Loperamide (reducing frequency) Codeine phosphate (pain) 5-HT3 antagonists Antidepressants/anticonvulsants
What is intestinal failure?
Inability to maintain nutrition/fluid status from obstruction, dysmotility, resection, congenital defect, or disease
Describe the three types of intestinal failure.
Type 1 - acute, self-limiting, 2 weeks
Type 2 - acute, post surgery, 4 weeks
Type 3 - chronic, short bowel syndrome
How should the three types of intestinal failure be treated?
1 - fluid, electrolytes, PPIs
2 - parenteral +/- enteral
3 - home parenteral nutrition
Define short bowel syndrome.
A short bowel < 200 cm (normally 250-1050)
What are the last resorts for short bowel syndrome?
Transplant, bowel lengthening.
Name the three types of home parenteral nutrition (HPN).
Peripherally inserted central catheter (PICC), central venous, and portacath
What are the complications of home parenteral nutrition?
Pneumothorax, arterial puncture, sepsis, thrombosis
Name the four types of malignant tumours in the large colon.
Polypoid adenocarcinoma, carcinoid, sarcoma, lymphatomous
What is the macroscopic view of polyps and tumours?
Pedunculated, sessile, flat, irregular surface/stalk
What are the majority of benign polyps in the colon?
Adenomas
Which genetic factors convert adenomas to carcinomas, then to metastasis?
17p/18q and p53
nm23 (mets)
Name the three main types of adenoma.
Tubular, villous, tubulovillous
Name the three Duke’s polyp categories.
A -> confined -> 90% prognosis
B -> through propria -> 70%
C -> lymph nodes -> 35%
Where are the majority (75%) of colon tumours located? Describe the presentation of both locations.
75% - descending and sigmoid -> blood PR, altered bowel habit, obstruction
25% - ascending -> anaemia, weight loss
Describe the two types of multiple polyp conditions in the large bowel.
Hereditary non-polyposis coli (HNPC, <100 polyps)
Familial adenomatous polyposis (FAP, >100 polyps)
HNPC is late; DNA mismatch repair
FAP is early; tumour suppression
What is diverticular disease?
Mucosal herniation through muscle coating
What is diverticulitis?
Inflammation of diverticulosis (which is diverticula). May also bleed.
How is diverticular disease found?
Usually incidental. Ba enema or sigmoidoscopy
What is the main presentation of diverticulitis? What are the complications?
LIF pain, sepsis, altered bowel habit
Abscess, perforation, haemorrhage, fistula, stricture
How should 1. uncomplicated, 2. complex, and 3. abscess diverticulitis be treated?
- oral abx, 2. Hertmann’s, 3. Drain/lavage
What is angiodysplasia?
A small vascular malformation of the gut, forming submucosal lakes of blood
What are the six main causes of bowel obstruction?
Cancer, stricture, volvulus, pseudo-obstruction, constipation, infarcation
How should bowel obstruction be treated?
Resus, operation, stenting
Give some ways STIs can be transferred to the GI tract.
Passive transfer of vaginal secretion, rimming, sex toys/fingers, systemic/local spread
Give some risk factors that make STI more likely.
< 25, change in partners, no condom, MSM, past history, deprivation, black ethnicity
How does Shigela spread as an STI? Who is at risk?
Faecal -> oral route. Bisexual/gay men
How do gonorrhoea and chlamydia spread? How do they both present?
Infected fluids in contact with mucous membranes
G: abdo pain, diarrhoea, rectal bleeding/discharge, tenesmus. Purulent exudate
C: similar, less severe. Anal discomfort/itch/discharge
What are the risk factors for LGV? How does it present?
Group sex, MSM, drug use, syphilis, hep C
Ulcers, inguinal/ano-rectal syndromes, fistulae
What is the differential diagnosis of ‘piles’?
Haemorrhoids, herpes, syphilis, LGV, anal cancer
How does syphilis present?
Primary: as a single solitary painless ulcer
Secondary: patches, ulcers, inflammation, hepatitis, procto-colitis
How can HPV lead to anal cancer?
Anal intraepithelial neoplasia: AIN
What are the general and dietary factors that may predispose to colorectal cancer?
Older age, obesity, smoking
High fat/sugar/alcohol/meat intake, low fibre
Describe the genetic aetiology of colorectal cancer.
75-95% have no genetic factors.
Genetic factors: APC (100% will get cancer), p53, UC and Crohn’s (but UC > Crohn’s).
Describe the four ways in which colorectal cancer can spread.
Direct, lymphatic, blood borne (liver/lung), or transcoelomic (rare)
Describe the three main ways in which colorectal cancer is picked up on.
Bowel screening (age 50-72) Urgent referral (red flag symptoms) - gastroenterologist decides whether SOPD/endoscopy Emergency (obstruction, perforation, bleeding etc)
Where do most colorectal cancers present - the left or right colon?
75% left, 25% right
Describe the difference between colorectal cancer that presents in the left vs right colon.
Left - rectal bleeds, incomplete evacuation, constipation
Right - Anaemia, tiredness, change in bowel habit, weight loss, colicky abdo pain, mass in abdomen
Which investigations are (primarily) used for colorectal cancer?
Sigmoidoscopy/colonoscopy (depending on tumour location) and CT colonography
(Barium enemas are now widely disregarded)
Describe the three main mass findings on endoscope.
Sessile (flat) or pedunculated (mushroom) polyp, or cancer
What is required to prepare a patient for a CT colonography?
Bowel perforation, faecal tagging, CO2 insuppuration, buscopan IV
Describe what a CT scan would show in the presence of colorectal cancer.
An irregular, narrow lumen, speculated outer border, sharp demarcation
Which tools are used to stage 1. colonic cancer and 2. rectal cancer?
- CT, 2. MRI
What are the three main types of surgery for colorectal cancer?
Open, laparascopic, robotic
Why is laparascopic surgery generally preferred to open surgery?
Leaves fewer scars/wounds, same results
Which things are done in colorectal paliation?
Stenting, radio/chemo therapy, defunctioning, bypass
What is rectal prolapse?
Prolapse of the anterior mucosa (partial) or full
How may patients describe an anal fissure?
Like passing glass
