General - Small Bowel Flashcards
What is angiodysplasia?
Formation of arteriovenous malformations between blood vessels (most commonly in the caecum and ascending colon)
What is the most common cause for bleeding from the small bowel?
Angiodysplasia
What causes congenital angiodysplasia?
- Hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)
- Heyde’s syndrome
What is the pathophysiology of acquired angiodysplasia?
- Reduced submucosal venous drainage in the colon
- Dilated and tortuous veins arise
- Loss of pre-capillary sphincter competency
- Formation of AVM (characterised by small tuft of dilated vessels)
In which three ways will angiodysplasia typically present?
- Asymptomatic (incidental diagnosis)
- Painless occult PR bleeding
- Acute haemorrhage
What are the main DDx for painless GI bleeding?
- Oesophageal varices
- GI malignancy
- Diverticular disease
- Coagulopathies
What abnormality may be seen in blood tests for a patient with angiodysplasia?
Iron deficiency anaemia
What imaging modality is required for any case of GI bleeding?
OGD +/- colonoscopy
Why is wireless capsule endoscopy beneficial in angiodysplasia?
Identifies the bleed and can be stemmed by administration of therapeutic agents at endoscopy
What risk factors are associated with poor outcome in angiodysplasia?
- Advancing age
- Liver disease
- Presentation with hypovolaemic shock
- Current inpatient
What is first line management for angiodysplasia?
Endoscopy
- bleeding vessel is subjected to current and argon, or can use banding, sclerotherapy
What is mesenteric angiography?
Super-selective catheterisation and embolisation that has shown to be bleeding (by extravasation of contrast dye)
What is the surgical management for angiodysplasia?
Bowel resection
What indications are there for surgery in angiodysplasia?
- Continuation of severe bleeding despite other management
- Severe acute life threatening GI bleed
- Multiple angiodysplastic lesions that cannot be treated medically
What does the term GEP-NETs refer to?
Gastroenteropancreatic neuroendocrine tumours - tumours arising from neuroendocrine cells in the tubular GI tract and pancreas with malignant potential
What is the WHO classification for GEP-NETs?
- Grade 1 - Well differentiated, mitotic count <2 per 10, ki index <3%
- Grade 2 - Well differentiated, mitotic count 2-20 per 10, ki index 3-20%
- Grade 3 - poorly differentiated, mitotic count >20 per 10, ki index >20%
What are the main risk factors for GEP-NETs?
- MEN1
- von Hippel-Lindau disease (VHL)
- Neurofibromatosis 1
- Tuberous sclerosis complex (TSC)
What symptoms do patients with GEP-NETs often present with?
- Vague abdo pain
- N+V
- Abdo distension
- Features of bowel obstruction
- Unintentional weight loss
- Palpable abdominal mass
What do well differentiated midgut NETs often present with?
Carcinoid syndrome
What is carcinoid syndrome?
Metastasis of a carcinoid tumour causes oversecretion of bioactive mediators eg. serotonin, prostaglandins
–> causes symptoms of flushing, abdo pain, diarrhoea, wheezing, palpitations
What specific lab tests should be done for a suspected GEP-NET in addition to routine bloods?
- Chromogranin A
- 5-HIAA
What imaging is indicated for GEP-NETs?
Small bowel NET –> CT enteroclysis
Gastric, duodenal, colorectal –> Endoscopy
What investigation can be done to establish disease extent/if no primary is found for a GEP-NET?
Whole bodu somatostatin receptor scintigraphy (SSRS)
What happens in a carcinoid crisis?
Severe hypotension due to overwhelming release of hormones
What is the management for the subtypes of gastric NETs?
Type 1+2 –> endoscopic resection + annual surveillance
Type 3 –> gastrectomy with lymph node clearance
What is the curative treatment for GEP-NETs?
Surgery - resection of the tumour and often regional lymph nodes
What agent can be used as prophylaxis pre or intra operatively for carcinoid crisis?
Somatostatin analogues
How can time between ingestion of food and development of symptoms be used to determine a likely causative agent of gastroenteritis?
Hours = Bacterial toxins Days = Viruses Weeks = Bacteria Months = Parasites
What does travellers diarrhoea refer to?
> 3 loose stools commencing within 24hrs of foreign travel
What is the difference between acute and chronic diarrhoea?
Acute <14 days
Chronic >14 days
What are the main risk factors for gastroenteritis?
- Poor food preparation
- Immunocompromise
- Poor personal hygiene
What clinical features will patients with gastroenteritis typically present with?
- Cramp like abdo pain
- Diarrhoea (+/- blood/mucus)
- Vomiting
- Pyrexia
- Night sweats
- Weight loss
- Dehydration
When is a stool culture indicated in gastroenteritis?
- Blood/mucus in stool
- Immunocompromised
- Severe/persistent
How long should a patient be excluded from work for in gastroenteritis?
48hrs from last episode of vomiting or diarrhoea
What viruses commonly cause gastroenteritis?
- Norovirus
- Rotavirus
- Adenovirus
What bacteria are common causes of gastroenteritis?
- Campylobacter
- E coli
- Salmonella
- Shigella
What bacterial toxins commonly cause gastroenteritis?
- Staphylococcus aureus
- Bacillus cereus
- Clostridium perfringes
- Vibrio cholera
What parasites are commonly indicated in travellers diarrhoea?
- Cryptosporidium
- Entamoeba histolytica
- Giadria intestinalis
- Schistosoma
What pathogen is commonly indicated in hospital acquired gastroenteritis? How is it acquired?
Clostridium difficile
Typically following broad spectrum Abx
What treatment is given for C. difficile infection?
IV fluid rehydration
PO Metronidazole
(Start vancomycin if severe/no improvement in 72hrs)
How does C. difficile affect the bowel?
Production of exotoxins A+B –> inflammatory response in bowel –> inflammatory exudate on colonic mucosa –> severe bloody diarrhoea (–> potentially toxic megacolon)
What are some non-infective causes of gastroenteritis?
- Radiation colitis
- IBD
- Microscopic colitis
- Chronic ischaemic colitis
