Gastrointestinal Flashcards
Define intestinal obstruction
Blockage to the lumen of the gut - often refers to blockage of the intra-abdominal part of the intestine
How do we classify bowel obstructions
- According to site
- Large/Small bowel/Gastric - Extent of luminal obstruction
- Partial/complete - According to mechanism
- Mechanical
- Paralytic - According to pathology
- Simple
- Closed loop
- Strangulation
- Intussusception
What percentage of intestinal obstruction occurs in the small bowel
60-75%
Describe the pathophysiology of small bowel disease
Bowel obstruction leads to bowel distension with increased secretion of fluid into the distended bowel leading to proximal dilation above the block
Increased secretion, swallowed air and bacterial fermentation lead to more dilation
What are the three results of untreated obstruction in the small bowel
Ischaemia
Necrosis
Perforation
What percentage of bowel obstructions is due to large bowel obstruction
25%
What is the pathophysiology of large bowel obstruction
Colon proximal to obstruction dilates and increased colonic pressure leads to decreased mesenteric blood flow resulting in mucosal oedema
This causes the arterial blood supply to become compromised leading to necrosis and perforation
What happens if the ileocaecal valve is competent in bowel obstruction
Caecum dilates and patient won’t feel unwell but will have massive distension
What happens if the ileocaecal valve is incompetent in bowel obstruction
Faeculent vomiting
What are the three different types of bowel obstruction
Intaluminal - something in the bowel
Intramural = something in the wall of the bowel
Extraluminal = something outside the bowel
What are the causes of intraluminal obstruction
Tumour
- Carcinoma and lymphoma
Diaphragm disease
- Fibrous fold in lumen
Meconium Ileus
- Content of neonate bowel becomes sticky
Gallstone Ileus
- Stone gets stuck in small bowel by eroding through gall bladder
Diaphragm disease is associated with what
NSAIDs
What are the causes of intramural obstruction
- Inflammatory disease
- Crohn’s/diverticulitis/ulcerative colitis - Tumours in bowel wall
- Hirschsprung’s disease
What is Crohn’s disease
Fibrosis of the bowel wall producing a cobblestone mucosa and granulomas
What is the pathophysiology of diverticular disease
Inflammation an fibrosis in the sigmoid colon - In low fibre diet mucosa is pushed through gaps in the muscular wall of the bowel due to increased pressure resulting in diverticulae
These act as cul de sacs where faeces can remain and become inflamed and rupture causing faecal peritonitis
What is Hirschsprung’s disease
Aganglionic segment of the bowel where there is no nerves meaning the bowel doesn’t contract leading to distal distension
What are the causes of extraluminal obstruction
Adhesions
Volvus
Intussusception
Peritoneal tumour
What is an adhesion
Fibrous band that sticks two bits of bowel together and the bowel is pulled and distorted
Normally seen post abdominal surgery
What is Volvulus
Bowel twisting around each other which cuts off blood supply = closed loop obstruction
What is intussusception
One part of intestine telescopes inside another
Where does a peritoneal tumour normally originate from
Ovarian cancer which spreads onto the peritoneum
What ares of the bowel of most likely to be affected with Volvos
Areas of the bowel with a mesentery ie. sigmoid colon
What are the causes of small bowel obstruction in adults
- Adhesions
- Hernia
- Crohns
- Malignancy
What are the causes of small bowel obstruction in children
Appendicitis Intesussception Volvus Atresia Hypertrophic pyloric stenosis
What are the two types of intesussuption
Idiopathic
Enteroenteral Intersussception
What is enteroenteral intersussception associated with
Cystic fibrosis
What are the uncommon causes of a small bowel obstruction
Radiation Gallstones Diverticulitis and Appendicitis Sealed small perforation Foreign bodies (Bezoars)
What are the symptoms of small bowel obstruction
- Early feculent projectile vomit
- Diffuse colicky pain
- Late constipation
- Distension
- Tenderness
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.
- Analgesia and anti-emetics.
- Antibiotics.
- Surgery e.g. laparotomy, bypass segment, resection
What are the causes of large bowel obstruction
- Age and race dependent
- Colorectal malignancy
- Volvulus
- Ischaemic structures
- hernia - Paediatric
- Imperforate anus
- Hirschsprung disease
What are the symptoms of large bowel obstruction
Abdominal discomfort Fullness Bloating Distension Late vomiting Colicky pain Obstipation Volvulus Sudden pain Localised tenderness
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 patient.
- Supplement O2.
- IV fluids to replace losses and correct electrolyte imbalance.
- Urinary catheterisation to monitor urine output.
Describe the progression from normal epithelium to colorectal cancer.
- Normal epithelium.
- 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 apc protein and so the apc/GSK complex isn’t formed -> beta catenin cannot be broken down so levels increase -> up-regulation of adenomatous epithelium gene transcription –> Adenoma forms
Describe the pathophysiology of Hereditary Non-Polyposis Colorectal Cancer.
There are no DNA repair proteins meaning there is a risk of colon cancer and endometrial cancers.
What are the implications of hereditary non-polyposis colorectal cancer
Cant use DNA damaging chemo as lack of DNA repair gene means DNA damage cant be recognised so apoptosis not activated
Where is the most common location for colorectal cancer
Sigmoid colon/rectum
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 are the symptoms of a left sided sigmoid cancer
rectal bleeding, altered bowel habit/obstruction, colicky pain
What are the symptoms of a right sided sigmoid cancer
iron deficiency anaemia, R iliac fossa mass, weight loss
What investigations might you do in someone who you suspect might have colorectal cancer?
Colonoscopy = gold standard!
It permits biopsy and removal of small polyps.
- Tumour markers are good for monitoring progress.
- Faecal occult blood is used in screening but not diagnosis.
Describe the coding system for resection of tumours
R0 = tumour completely excised locally R1 = Microscopic involvement of margin by tumour R2 = Macroscopic involvement of margin by tumour
Describe the staging system for cancer
- T – T1 (invades submucosa) -> T2 (muscularis propria) -> T3 (bowel wall) -> T4 (peritoneum)
- N – N1 (spread to lymph nodes) -> N2 (spread to lymph nodes above diaphragm)
- M – M1 = surrounding structure involvement (liver)
What are the non-infectious causes of diarrhoea
hormonal Radiation Chemical Anatomical Irritable bowel Inflammatory Neoplasm
Name some causative agents of diarrhoea
Rotavirus Shigella E.coli Salmonella type Salmonella paratyphoid Hepatitis A Hepatitis E Vibrio cholerae
Define gastroenteritis
Diarrhoea +/- vomiting due to an enteric infection
Define acute diarrhoea
3+ episodes of partially formed watery stools for <14 days
Define dysentery
Infectious diarrhoea and blood
Define travellers diarrhoea
Gastroenteritis occurring under 2 weeks after entering a new country
What is the pathogenesis of norovirus
Single strand RNA
What are the symptoms of norovirus
Vomiting
Watery diarrhoea
Cramps
Nausea
What is the treatment for norovirus
Self limiting disease
Supportive with loperamide
What Id the pathophysiology of rotavirus
Double stranded DNA
What are the symptoms of rotavirus
2-day incubation –> 3-8 day symptoms
Watery diarrhoea
Vomiting
fever
Abdominal pain
What is the management of rotavirus
Prevention through vaccination
ETEC is the most common cause of what
Traveller’s Diarrhoea
What is the pathophysiology of ETEC
Gram -ve bacillus anaerobe that is heat stable toxin
What are the symptoms of ETEC
1-3 day incubation with 3-4 days symptoms
Watery diarrhoea and cramps
What is the management of ETEC
Rehydration
Anti-motility agents (Loperamide)
What is the pathophysiology of clostridium perfringens
Gram +ve anaerobe which produces enterotoxins
Spores survive cooking and multiply in unrefrigerated storage
What are the symptoms of clostridium perfringens
sudden onset diarrhoea and cramps normally for 24hr
What is the management of clostridium perfringens
Supportive
What is the pathophysiology of vibrio cholerae
Gram -ve flagellated aerobe vibrio transmitted by faecally contaminated water
Servers 01 and 0139 are pathogenic
What are the symptoms of vibrio cholerae
2-5 days incubation Rice water stools Vomiting Dehydration Circulatory collapse = death
What is the management of vibrio cholerae
Prevention through clean water and vaccination
Treatment with oral rehydration salts/IV rehydration and antibiotics
What is the pathophysiology of shigella
Gram -ve
What are the symptoms of shigella
1-2 days incubation and 5-7 day symptoms Watery/bloody diarrhoea Pain Cramping rectal pain Fever
What is the management of shigella
Supportive
Zinc for children
Antibiotics (Ciprofloxacin and azithromycin)
What is the pathophysiology of campylobacter jejuni
Gram -ve bacillus - very common in meat and milk
What are the symptoms of campylobacter jejuni
2-5 day incubation Bloody diarrhoea Pain Fever Headache
What is the management of campylobacter jejuni
Supportive - antibiotics if invasive (Macrolide and doxycycline)
What is the pathophysiology of salmonella enterocolitis
gram -ve anaerobic bacilli
What are the symptoms of salmonella enterocolitis
12-36hr exposure Bloody diarrhoea Crampls Fever Invasive infection = sepsis, meningitis, osteomyelitis
What is the management of salmonella enterocolitis
Supportive - antibiotics for invasive infection (Quinolone and macrolide)
What is the pathophysiology of clostridium difficile
Gram +ve aerobic bacilli that produces enterotoxin A and B
Antibiotic use destroys the competing flora so there is less inhibition of C.diff
Spread by the faeco-oral route
Symptoms of clostridium difficile
Watery diarrhoea
Fulminant colitis
How would you investigate someone thought to have C.diff
Test stool samples for toxins
Tissue samples obtained at sigmoidoscopy
What antibiotics can cause C.diff
Clindamycin
Ciprofloxacin
Co-amoxiclav
Cephalosporins
What is the treatment for C.diff
Metronidazole
Vancomycin
Name some other causes of gastroenteritis
Protozoa (Giardia, cryptosporidium)
Helminths (Schistosome, strongyloide)
How can we prevent diarrhoea
- Rotavirus and measles vaccination
- Promote early breastfeeding
- Promote hand washing with soap
- Improve water supply quantity and quality
- Community wide sanitation promotion
What groups are most at risk of diarrhoea
- Persons of doubtful hygiene or unsatisfactory hygiene at home, work or school
- Children who attend pre-school or nursery
- People who work in preparing or serving unwrapped/uncooked food
- Health care workers or social care staff working with vulnerable people
What is a notifiable disease
Diseases, infections and conditions specifically listed as notifiable under public health
Name some examples of notifiable diseases
Anthrax Cholera Plague Rabies SARS Smallpox Yellow fever Leprosy Malaria Botulism
Name some examples of vaccine preventable diseases
Diptheria Measles Mumps Rubella Tetanus Whooping cough Acute meningitis Meningococcal septicaemia
What diseases need specific control measures
Acute infectious hepatitis Foodborne - food poisoning - botulism - Enteric fever - infectious blood diarrhoea Scarlet fever Tuberculosis
What are some diseases notifiable
Very dangerous
Vaccine preventable
Diseases that need specific control measures
What is the role of surveillance in notifiable diseases
Detection of any changes in disease
- Outbreak detection
- Early warning
- Forecasting
Track changes in disease
- Extent and severity of disease
- Risk factors
How do you protect a community from notifiable disease
Investigate - control tracing, partner notification, lookback exercises
Identify and protect vulnerable people
(Chemoprophylaxis, immunisation and isolation)
Exclude high risk persons from high risk settings
Educate, inform, raise awarnesss and promote health
Coordinate multi-agency responses
What are the steps that must be taken when notifying about a disease
- Notification
- all suspected cases without delay - Contact tracing
- Any person with close contact in past 7 days - Prophylaxis
- Advice (warn about symptoms and glass spot tests)
- Antibiotics chemoprophylaxis (Close contacts, ciprofloxacin and rifampicin)
- Immunisation (If available serogroup)
What are the two forms of active immunity
Cell mediated immunity
Antibody mediated immunity
What is passive immunity
Protection provided from the transfer of antibodies from immune individuals
What is the most common form of passive immunity
Cross placental transfer of antibodies from mother to child or via transfusion of blood or blood products
Protection is temporary
Describe passive immunisation through the use of human normal immunoglobulin
Increases the persons antibody level to that specific infection providing protection
From plasma donors and contains antibodies to infectious disease currently prevalent
When is human normal immunoglobulin used
Immunocompromised children Tetanus Hepatitis B Rabies Varicella Zoster
What is an active immunisation
Vaccination stimulates immune response and memory to a specific antigen/infection
What are vaccines made from
inactivated (Killed) (Pertussis, inactivated polio)
Attenuated live organisms (yellow fever, MMR, polio and BCG)
Secreted products (Tetanus, diphtheria toxoids)
Constituents of cell walls (HepB) or recombinant components (Experimental)
Define vaccine failure
Small proportion of individuals get infected despite vaccination
Define primary vaccine failure
Persons doesn’t develop immunity from vaccine
Define secondary vaccine failure
Initially responds but protection wanes overtimes
What are the two presentations of meningococcal infection
Meningitis
Septicaemia
Meningococcal infection is caused by what
Neisseria meningitidis
Serogroups B, C, A, Y and W135
How is meningococcal infection spread
Person to person by inhaling respiratory secretions from mouth and throat or by direct contact (kissing)
What can meningococcal infection cause
Brain abscess Brain damage Seizure disorder Hearing impairment Focal neurological disorders Organ failure Gangrene Auto-amputation Death
What is the management of meningococcal infection
Antibiotic therapy: Cefotaxime and ceftriaxone
Supportive therapy
What are the routine childhood immunisations
Meningitis C vaccine
meningitis B vaccine
Quadrivalent (A, C, W135, Y)
What immunisations are given the eight week baby check
Diptheria, tetanus, pertussis, polio, heaemophilus influenza type B
Pneumococcal
Meningococcal group B
Rotavirus gastroenteritis
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.
Describe h.pylori.
A gram negative bacilli with a flagellum.