GI Flashcards
Give 5 causes of diarrhoeal infection.
- Traveller’s diarrhoea.
- Viral e.g. rotavirus, norovirus.
- Bacterial e.g. E.coli.
- Parasites e.g. helminths.
- Nosocomial e.g. c.diff.
Give 5 causes of non-diarrhoeal infection.
- Gastritis/peptic ulcer disease e.g. h.pylori.
- Acute cholecystitis.
- Peritonitis.
- Typhoid/paratyphoid.
- Amoebic liver disease.
Give 3 ways in which diarrhoea can be prevented.
- Access to clean water.
- Good sanitation.
- Hand hygiene.
What is the diagnostic criteria for traveller’s diarrhoea?
> 3 unformed stools per day and at least one of:
- Abdominal pain.
- Cramps.
- Nausea.
- Vomiting.
It occurs within 3 days of arrival in a new country.
Give 3 causes of traveller’s diarrhoea.
- Enterotoxigenic e.coli (ETEC).
- Campylobacter.
- Norovirus.
Describe the pathophysiology of traveller’s diarrhoea.
Heat labile ETEC modifies Gs and it is in a permanent ‘locked on’ state. Adenylate cyclase is activated and there is increased production of cAMP. This leads to increased secretion of Cl- into the intestinal lumen, H2O follows down as osmotic gradient -> diarrhoea.
Which type of e.coli can cause bloody diarrhoea and has a shiga like toxin?
Enterohaemorrhagic e.coli (EHEC) aka e.coli 0157.
What does EIEC stand for?
Enteroinvasive e.coli.
Which type of e.coli is responsible for causing large volumes of watery diarrhoea?
Enteropathogenic e.coli (EPEC).
What does EAEC stand for?
Enteroaggregative e.coli.
What does DAEC stand for?
Diffusely adherent e.coli.
What is the leading cause of diarrhoeal illness in young children?
Rotavirus.
There is a vaccine - rotarix.
Name a helminth responsible for causing diarrhoeal infection.
Schistosomiasis.
Give 5 symptoms of helminth infection.
- Fever.
- Eosinophilia.
- Diarrhoea.
- Cough.
- Wheeze.
Briefly describe the reproductive cycle of schistosomiasis.
- Fluke matures in blood vessels and reproduces sexually in human host.
- Eggs expelled in faeces and enter water source.
- Asexual reproduction in an intermediate host.
- Larvae expelled and penetrate back into human host.
Why is c.diff highly infectious?
It is a spore forming bacteria. (gram positive)
Give 5 risk factors for c.diff infection.
- Increasing age.
- Co-morbidities.
- Antibiotic use.
- PPI
- Long hospital stays.
Describe the treatment for c.diff infection.
Metronidazole and vancomyocin (PO).
Name 5 antibiotics prone to causing c.diff infection.
- Ciprofloxacin.
- Co-amoxiclav.
- Clindamycin.
- Cephlasporins.
- Carbapenems.
- Rule of C’s!
What can helicobacter pylori infection cause?
H.pylori produces urease -> ammonia -> damage to gastric mucosa -> neutrophil recruitment and inflammation.
This can cause gastritis; peptic ulcer disease and gastric cancer.
(note: yes - urea does exist in the stomach)
Describe h.pylori.
A gram negative bacilli with a flagellum.
Describe the treatment for H.pylori infection.
Triple therapy: 2 antibiotics and 1 PPI e.g. omeprazole, clarithromyocin and amoxicillin.
Who is most likely to be affected by diverticular disease?
Older patients and those with low fibre diets.
Describe the pathophysiology of diverticulitis.
Out-pouching of bowel mucosa -> faeces can get trapped here and obstruct the diverticula -> abscess and inflammation -> diverticulitis.
What part of the bowel is most likely to be affected by diverticulitis?
The descending colon.
What is acute diverticulitis?
A sudden attack of the swelling in the diverticula. Can be due to surgical causes.
Describe the signs of acute diverticulitis.
Similar to the signs of appendicitis but on the left side e.g. pain in the left iliac fossa region; fever; tachycardia.
Name the 3 broad categories that describe the causes of intestinal obstruction.
- Blockage.
- Contraction.
- Pressure.
Intestinal obstruction: give 3 causes of blockage.
- Tumour.
- Diaphragm disease.
- Gallstones in ileum (rare).
Intestinal obstruction: what is thought to cause diaphragm disease?
NSAIDS.
Intestinal obstruction: give 3 causes of contraction.
- Inflammation.
- Intramural tumours.
- Hirschprung’s disease.
Describe how Crohn’s disease can cause intestinal obstruction.
Crohn’s disease -> fibrosis -> contraction -> obstruction.
Describe how Diverticular disease can cause intestinal obstruction.
Outpouching of mucosa -> faeces trapped -> inflammation in bowel wall -> contraction -> obstruction.
What is Hirschprung’s disease?
A congenital condition where there is a lack of nerves in the bowel and so motility is affected. This leads to obstruction and gross dilatation of the bowel.
Intestinal obstruction: give 3 causes of pressure.
- Adhesions.
- Volvulus.
- Peritoneal tumour.
Intestinal obstruction: what are adhesions?
Adhesions often form secondary to abdominal surgery. Loops of bowel stick together and the bowel is pulled and distorted. 40% of intestinal obstructions are due to adhesions.
Intestinal obstruction: what causes adhesions?
Adhesions often form secondary to abdominal surgery.
Intestinal obstruction: what is volvulus?
Volvulus is a twist/rotation in the bowel (forms a closed loop obstruction). There is a risk of necrosis.
Intestinal obstruction: which areas of the bowel are most likely to be affected by volvulus?
Volvulus occurs in free floating areas of the bowel e.g. bowel with mesentery. The sigmoid colon has a long mesentery and so can twist on itself.
Give 4 common causes of small bowel obstruction in adults.
- Adhesions.
- Hernias.
- Crohn’s disease.
- Malignancy.
Which is more common: small bowel obstruction or large bowel obstruction?
Small bowel obstruction is more common; it makes up 75% of intestinal obstruction.
Give 3 common causes of small bowel obstruction in children.
- Appendicitis.
- Volvulus.
- Intussusception.
Intestinal obstruction: what is intussusception?
Intussisception is when part of the intestine invaginates into another section of the intestine -> telescoping. It is causes by force in-balances.
Define hernia.
The abnormal protrusion of an organ into a body cavity it doesn’t normally belong.
What are the risks of hernia’s if left untreated?
They can become strangulated and you may not be able to return them into their correct body cavity (irreducible).
Give 2 symptoms of hernia.
- Pain.
2. Palpable lump.
Give 5 symptoms of small bowel obstruction.
- Vomiting.
- Pain.
- Constipation.
- Distension.
- tenderness.
Would dilatation, distension and increased secretions be seen proximal or distal to an intestinal obstruction?
Proximal.
Give 4 signs of small bowel obstruction.
- Vital signs e.g. increased HR, hypotension, raised temperature.
- Tenderness and swelling.
- Resonance.
- Bowel sounds.
What investigations might you do in someone who you suspect to have a small bowel obstruction?
- Take a good history - ask about previous surgery (adhesions).
- FBC, U&E, lactate.
- X-ray.
- CT, ultrasound, MRI.
What is the management/treatment for small bowel obstruction?
- Fluid resuscitation.
- Bowel decompression (taking needle and draining)
- Analgesia and anti-emetics.
- Antibiotics.
- Surgery e.g. laparotomy, bypass segment, resection.
Give 2 common causes of large bowel obstruction.
- Colorectal malignancy.
2. Volvulus (especially in the developing world).
Give 5 symptoms of large bowel obstruction.
- Tenesmus. (wanting to poo all the time)
- Constipation.
- Abdominal discomfort.
- Bloating.
- Vomiting.
- Weight loss.
What investigations might you do in someone who you suspect to have a large bowel obstruction?
- Digital rectal examination.
- Sigmoidoscopy.
- Plain X-ray.
- CT scan.
Describe the management for a large bowel obstruction.
- Fast the pt.
- Supplement O2.
- IV fluids to replace losses and correct electrolyte imbalance.
- Urinary catheterisation to monitor urine output.
Give 3 consequences of untreated intestinal obstructions.
- Ischemia.
- Necrosis.
- Perforation.
Describe the progression from normal epithelium to colorectal cancer.
- Normal epithelum.
- Adenoma.
- Colorectal adenocarcinoma.
- Metastatic colorectal adenocarcinoma.
Define adenocarcinoma.
A malignant tumour of glandular epithelium.
What is familial adenomatous polyposis?
Familial adenomatous polyposis is a genetic condition where you develop thousands of polyps in your teens.
Describe the pathophysiology of familial adenomatous polyposis.
There is a mutation in the apc protein and so the apc/GSK complex isn’t fomred -> beta catenin levels increase -> up-regulation of adenomatous gene transcription.
Describe the pathophysiology of HNPCC (Hereditary nonpolyposis colorectal cancer).
There are no DNA repair proteins meaning there is a risk of colon cancer and endometrial cancers.
How can adenoma formation be prevented?
NSAIDs are believed to prevent adenoma formation.
What is the treatment for adenoma?
Endoscopic resection.
What is the treatment for colorectal adenocarcinoma?
Surgical resection can be done when there is no spread. Remember to balance risks v benefits. The patient has a pre-op assessment.
What is the treatment for metastatic colorectal adenocarcinoma?
Chemotherapy and palliative care.
Give 3 reasons why bowel cancer survival has increased over recent years.
- Introduction of the bowel cancer screening programme.
- Colonoscopic techniques.
- Improvements in treatment options.
Give 5 risk factors for colorectal cancer.
- Low fibre diet.
- Diet high in red meat.
- Alcohol.
- Smoking.
- A PMH of adenoma or ulcerative colitis.
- A family history of colorectal cancer; FAP or HNPCC.
What can affect the clinical presentation of a colorectal cancer?
How close the cancer is to the rectum affects its clinical presentation.
Give 3 signs of rectal cancer.
- PR bleeding.
- Mucus.
- Thin stools.
- Tenesmus.
Give 2 signs of a left sided/sigmoid cancer.
- Change of bowel habit e.g. diarrhoea, constipation.
2. PR bleeding.
Give 3 signs of a right sided cancer.
- Anaemia.
- Mass.
- Diarrhoea that doesn’t settle.
Describe the emergency presentation of a left sided colon cancer.
The LHS of the colon is narrow and so the pt is likely to present with signs of obstruction e.g. constipation; colicky abdominal pain; abdominal distension; vomiting.