Gastroenterology Flashcards
What is the most common bacterial cause of gastroenteritis in the adults in the uK?
Campylobacter species (campylobacter jejuni most common). Classically have a several day prodrome of feeling generally unwell before developing profuse sometimes bloody diarrhoea. incubation period = 1-6 days.
What is the incubation period of salmonella enteritidis and how does it typically present?
Incubation period of 12-24 hours (much shorter than campylobacter!). Presents with high fever + severe vomiting +/- bloody diarrhoea.
What is the incubation period of staph aureus associated gastroenteritis?
Incubation period of 1-6 hours (very short!) with sudden onset abdominal pain and vom
Classical presentation of Irritable Bowel Syndrome (IBS)?
AT LEAST 6 MONTHS Hx of abdominal pain +/- bloating +/- change in bowel habit. Typical features = abdo pain associated with defecation, straining or urgency when defecating, symptoms worse with eating, passing rectal mucus.
How should you initially assess someone with suspected IBS?
Discuss effect on QoL, suggest food diary for triggers, discuss concomitant anxiety/depression, perform abdo exam and DRE, bloods incl FBC, vit B12 + folate + total IgA and tTG (IgA tissue transglutaminase antibody) - to exclude malabsorption + coeliac pathology.
Exclude colorectal cancer red flag symptoms (loss of appetite, DVT, unexplained weightloss, unexplained anal mass/ulceration, iron deficiency anaemia in 60+ or iron deficiency anaemia + rectal bleeding in adult <50, abdominal pain with rectal bleeding or weightloss, change of bowel habit in 60 or over)
What are common management approaches for IBS?
Signpost to GutsCharity and The IBS Network for IBS info. Optimise anxiety/depression management. Food diary and adjust diet according to symptoms (^ fibre if constipation, reducing if diarrhoea).
Symptom management:
Constipation - bulk-forming laxative (ispaghula husk) 1st line, then add in other laxatives if needed. LACTULOSE NOT RECOMMENDED IN IBS. If ongoing >12 months despite laxatives - 3 month trial of Linaclotide
Diarrhoea - loperamide
Abdo cramps - Mebeverine, peppermint oil capsules, alverine. If persists, trial of low dose tricyclic ie amitriptyline.
Refer to gastroenterology if persistent symptoms
What are the key differences in clinical presentation of Crohn’s disease v Ulcerative Colitis?
Both: diarrhoea, abdominal pain, erythema nodosum (tender red nodules on anterior shins caused by inflammation of subcutaneous fat)
UC: bloody diarrhoea more common, tenesmus (feeling of needing to empty bowels even though already empty), association with primary sclerosing cholangitis and uveitis, higher risk of associated colorectal cancer
Crohn’s: weightloss more common, upper GI symptoms, mouth ulcers, perianal disease, increased risk of colorectal cancer but not as much as UC
What are the key histological differences between Crohn’s and Ulcerative Colitis?
Ulcerative colitis: between ileocaecal valve and the rectum, continuous, restricted to the mucosa + submucosa, crypt abscesses, reduced number of goblet cells, pseudopolyps on endoscopy
Crohn’s: entire GI tract, full thickness, skip lesions / not continuous, granulomas, increased number of goblet cells, ‘cobble-stone’ appearance on endoscopy
TERMINAL ILEUM IS THE MOST COMMONLY AFFECTED / WORST AFFECTED AREA
What are the key differences in the associated conditions of Crohn’s and UC?
UC: higher ^ risk of colorectal cancer, primary sclerosing cholangitis, uveitis.
Crohn’s: ^ risk of colorectal cancer but not as much as UC, ^ risk of gallstones + renal stones, higher risk of bowel obstruction and fistula.
What is the 1st line investigation for suspected coeliac disease?
Serum IgA tissue transglutaminase (IgA TTG) and total IgA
They should have been eating gluten containing foods in at least one meal per day for the preceding 6 weeks before the test is done.
How should you manage serology results for coeliac disease if it shows there is an IgA deficiency?
If there is an IgA deficiency it will give a false negative IgA TTG. So you should check IgG TTG and total IgG. igG is less specific so you should have a low threshold for referral to gastro.
How should you manage positive IgA TTG?
Refer to gastroenterologist. Definitive diagnosis is endoscopic intestinal biopsy = subtotal villous atrophy
Which part of the GI tract does coeliac disease especially affect?
The small intestine, in particular the jejunum
What is the most common cause of traveller’s diarrhoea?
E.coli
What is the typical presentation of diarrhoea associated with giardia lamblia?
= a protozoa
present w/ watery (non-bloody) diarrhoea + bloating. can lead to steattorhoea / malabsorption.
risk factors = foreign travel, male-male sex, drinking / swimming in lake/river water.
Explain the pathway of bilirubin metabolism?
Breakdown of RCCs = in the reticuloendothelial system (liver + spleen) = into haem + globin.
Haem then broken into bilirubin + iron
Globin + iron recycled.
The bilirubin = initially unconjugated = lipid soluble = binds to albumin for transport .
Albumin-bilirubin complex enters liver -> gets conjugated in liver (by B-UGT enzymes) = water-soluble -> excreted in bile into duodenum -> in large intestine, conjugated bilirubin converted into urobilinogens by bacterial enzymes.
Urobilinogens = majority of urobilinogens excreted in faeces (gives brown colour), some urobilinogens reabsorbed in the bowel where some goes back into liver and some excreted in urine (gives urine yellow colour).
When should you transfuse platelets in the context of an upper GI bleed?
When active bleeding + plts <50
What should you give in the context of derranged clotting profile in an upper GI bleed?
If APTT, PT (normal = 11-13) or INR is more than 1.5 times the normal, then you should give FFP (fresh frozen plasma)
If fibrinogen remains <1.5g/L despite FFP, then you should give cryoprecipitate as well.
What should you give patients on warfarin presenting with an upper GI bleed?
If active bleeding from upper GI bleed + on wafarin = give prothrombin complex concentrate
If on warfarin and no active bleeding = normal warfarin procotol
When should you perform endoscopy in patients presenting with upper GI bleed?
Emergency endoscopy immediately after resuscitation in those presenting with acute SEVERE upper GI bleed
For everyone else, within 24 hrs
What scoring systems should be used during an upper GI bleed?
Pre-endoscopy = Blatchford -> for assessing liklihood of patient with upper GI bleed needing an intervention including endoscopy or transfusion Post-endoscopy = Rockall -> prognostic score, assessing likelihood of rebleeding + death
How should NON-VARICEAL GI bleed be managed
DO NOT routinely give IV PPI pre-endoscopy
If evidence of non-variceal source with recent bleeding on endoscopy then can start IV PPI post-endoscopy
DO NOT USE ADRENALINE ALONE to achieve haemostasis, instead use either clips, thermal coagulation or fibrin/thrombin coagulation +/- adrenaline alongside
How should you manage patients who rebleed after the initial endoscopy?
If unstable -> interventional radiology / surgery
If stable -> repeat endoscopy if rebleed or doubt re original haemostasis
How should VARICEAL upper GI bleed be managed?
IV antibiotic prophylaxis
+ IV Terlipressin (-> STOP AFTER adequate haemostasis or max 5 days)
both started at initial presentation if variceal bleed suspected in addition to resuscitation with blood products as necessary.
For oesphageal varices -> 1st line haemostasis = BAND ligation
For gastric varices -> N-butyl-2-cyanoacrylate via endoscopic injection
if 1st line fails for either oesophageal or gastric varices = TIPS (transjugular intraheptic portosystemic shunts)
