Diarrhoea Flashcards
what is diarrhoea?
A symptom that occurs in most conditions
- loose/ watery stool
- more than 3 times a day
- acute diarrhoea (less than 2 weeks)
what is the pathophysiology behind diarrhoea
- unwanted substance stimulates secretion from epithelial cells
- colon can’t absorb all the water
how is water moved across the gut?
via transcellular and paracellular
follows osmotic forces by movement of electrolytes and nutrients (Na)
what is osmotic diarrhoea?
- water drawn into gut
- high osmotic pressure
- due to not being able to absorb molecules in gut
- stool volume will be moderately increased
- if you stop eating then it reduces
what is secretory diarrhoea
- due to an infection
- water is actively secreted into gut
- epithelial cells are trying to flush out the infection
- dies not reduce when food consumption is reduced
how does CFTR cause more water to be pumped out?
- toxin or virus inside the cell
- increases CAMP
- causes the CFTR to pump out more Cl
- this causes the movement of Na ions moving paracellular
- this causes water to follow
how can a lack of lactase enzyme cause diarrhoea?
lactose can’t be broken down
it accumulates inside the gut
water is drawn into the colon
this will settle if you stop ingesting lactose
what are some reasons of diarrhoea?
- too little absorption of sodium ( where sodium goes water goes) so it will stay in the gut
due to: - bowel resection -> reduced surface area
- inflamed surface -> wont do job properly
- intestinal rush -> no contact time for nutrients to be absorbed
what is constipation?
- difficulty to pass stool
- lumpy/hard stool
- feeling of incomplete evacuation
-feeling of obstruction or blockage
what are some risk factors of constipation
- female (x3 male)
-certain meds - low physical activity
- increasing age and also very young kids
what are the three main reasons for constipation?
- normal transit constipation
-slow colonic transport
-defaecation problems
what are the reasons for slow transit constipation
psychological stressors
what are reasons for slow colonic transporters
- large colon
- slow transport so more water will be reabsorbed and stool will be hard
-large distended colon slowers transport - fewer pacemakers so fewer peristaltic movements
- nervous system disease
how do defection problems arise
- can’t coordinate muscles of defecation
- problems in pelvis / pelvic floor
what is some treatment for constipation
-psycological support
-increased fluid intake
-increased activity
-increased dietary fibre
-laxatives
this is an X-ray image of a build up if stool
what is appendicitis?
- inflammation of appendix
- appendix is a diverticulum of caecum
- it has a separate blood supply to the caecum from ilecolic branch of SMA
why is the location of the appendix important
- different postions have different presentations
what is acute appendicitis
acute: inside starts to swell and inflammation can lead to outside and cause necrosis and can perforate the appendix
can lead to peritonitis -> all the intense of the appendix has now entered the bowel
what is the main cause for appendicitis
- something that blocks the entrance of the appendix
- will cause a high pressure in appendix
- venous pressure rises
- arteriole blood wont be able to enter
- you get ischemia
- faecolith can block (hard stool)
- lymphoid hyperplasia: lymphoid tissue enlarges due to recent infection and blocks the entrance
- a foreign body can block off the appendix
what is the classic presentation of appendicitis
- poorly localised peri umbilical pain
- so painful => anorexia don’t want to eat
- nausea
-low grade fever
why do you get poor localised pain with appendicitis?
- appendix is an intraperitoneal structure
- visceral afferents are stimulated
- pain is referred to T10,9
- appendix is inflamed and can touch parietal peritoneum
what type of pain do do you get with appendicitis when the appendix is recto -caecal or pelvic
- wont get right iliac fossa pain like normal
- supra pubic pain, right sided rectal or vaginal pain
what are two cases where appendicitis is hard to diagnose
- children
- pregnant women
what are signs that a patient has appendicitis
- slightly ill
- still (painful to move)
- localised right quadrant tenderness
- rebound tenderness in right iliac fossa
what is McBurney’s point?
- classic location of the appendix
- 2/3 way of the umbilicus
what is the diagnosis of appendicitis
- blood tests - raised WBC
- rebound tenderness
-pregnancy test / urine dip (could be an ectopic pregnancy and don’t want to do invade surgery if they have a UTI) - CT will show a distended appendix
what is the treatment of appendicitis
- open appendicectomy
- laparoscopic appendicectomy
what is diverticulosis?
- outmatching of the mucosa and the submucosa that herniate through the muscular layers
- asymptomatic
-occurs in the colon - occurs where nutrient vessels penetrate the bowel wall
- pressure build up can cause outpouches
- diverticular are not inflamed or infected.
what is acute diverticulitis
- when diverticula become inflamed or perforate
- due to blockage (faeces)
- this inflammation can cause passage for bacteria and lead to perforation
what is uncomplicated diverticulitis
- inflammation and small abscess confined to colonic wall
what is complicated diverticulitis
- larger abscess, fistula and perforation
what are some symptoms of acute diverticulitis
- abdominal pain (normally left lower quadrant)
- fever
-bloating
-constipation (inflammation can block lumen and block feaces)
-haematochezia - lots of blood loss
what are signs of acute diverticulitis
- localised abdominal tenderness
-distension
-reduced bowel sounds
-signs of peritonitis
diagnosis of acute diverticulitis
- blood test: raised WBC
- ultrasound scan (can see the diverticula)
-CT scan (fistula)
-Colonscopy
treatment of acute diverticulitis
- antibiotics, fluid resuscitation, analgesia
- surgery is there if a large perforation that needs to be drained
what are the last sections of the GI tract
- rectum and anal canal
What is the rectum?
- 12-15cm passes through pelvic floor
- has continuous band of outer longitudinal muscles
- curved shape
- temporary storage of faeces
- some are covered in peritoneum and some are extra peritoneal
what is the blood supply to the rectum?
superior: superior rectal artery (branch of IMA)
Middle: Internal iliac
Inferior: pudendal artery
Venous drainage of the rectum
Portal via superior rectal vein
systemic drainage through internal iliac vein
where is the start of the anal canal?
- starts at the proximal border of the anal sphincter complex
-rectum enters into it anteriorly - puborectalis muscle acts like a sphincter
what is the separation point of the anus and the rectum?
- anorectal ring
what are some features of the rectum to allow a constant continence?
- distensible rectum (so it can expand when the faeces is big)
-firm bulky faeces - allows sphincter to work properly - normal anorectal sling
- anal cushions - they contain veins, when they swell they increase the sphincter mechanism in the anus
- normal anal sphincters
what is the internal involuntary sphincter in the anus?
- thickening of the circular smooth muscle of the gut
- this is autonomic and contributes to 80% of resting anal pressure
what is the external anal sphincter
- responsible for 20% of resting anal pressure
- striated muscle
Deep section: Merges with fibres from elevator ani and joins with pubo recitals to form a sling - supplied by pudendal nerve and is conscious control (so we can control when we poo)
order of defaecation
- mass movement due to stomach stretching (after eating)
- rapid peristalsis moving faeces from distal colon to rectum
- distension in rectum as it filles with faeces
- contraction in the rectum and sigmoid colon
- relaxation of internal anal sphincter
- contraction of external anal sphincter (last barrier to release faeces)
Can either lead to: - defecation
- Delay
what are the muscles and sphincters involved in defaecation
- relaxation of the external sphincter
- relaxation of the puborectalis muscle
- forward peristalsis in rectum, sigmoid colon
- increased abdominal pressure
what occurs in the body when faeces is delayed
- contraction in the external sphincter
- contraction of the puborectalis muscle
- reverse peristalsis in the rectum
label this anus
what is the dentate line in the anus
junction of the hindgut and the proctodaeum
what is found above the dentate line in the anus
- visceral pain receptors
-columnar epithelium - only time things will be painful here is if you get a big stretch response or perforation/ulceration
what is found below the dentate line
- somatic pain receptors (comes from ectoderm)
-stratifies squamous cell
what are anal cushions and how are they related to haemorrhoids?
- anus divides into a venous plexus
- anal cushions are area with lots of veins
- when they fill they swell muscles
- this aids with continence
- the connections between veins and arteries = haemmorrhoids
- sometimes this haemmorrhoids can burst
what is an internal haemorrhoid?
- found above the dentate line
- due to loss of connective tissue support
-relatively painless ( due to it being above the dentate line)
-enlarges and prolapses through anal canal
-bleed bright red
-puritis (itchy)
treatment of internal haemorrhoid
- increased hydration and fibre to keep stool smooth
- avoid straining
-rubber band ligation
-surgery - if they get bad tie a rubber band at base and it will necroses
describe the grades of haemorrhoid
what is an external haemorrhoid
below the dentate line
swelling if anal cushion which can thrombus
very painful
need them surgically removed
what is an anal fissure?
- linear tear in the anoderm (in posterior midline)
-very painful as its below the dentate line (stratified squamous) can pass some blood
-can be due to passing of hard stool
what is the underlying causation of an anal fissure
- high internal anal sphincter tone (more tension)
- reduced blood flow to anal mucosa
treatment of an anal fissure
- hydration, dietro fibre (avoid tough stool)
- pain relief
- relax anal sphincter to allow to heal -> warm baths, meds
what is haematochezia
- when you bleed out the anus due to small break in skin or mucosa, bright red
Due to: - diverticulitis
-angiodysplasia
-colitis
-colorectal cancer (erodes through blood vessels) - anorectal disease
- fast transit causing GI bleed
what is melaena
- thick dark black stool ( due to haemoglobin being altered by digestive enzymes and gut bacteria)
-smells bad
common causes for melaena
- upper GI bleeding
-peptic ulcer disease
-variceal bleeds
-upper GI malignancy
-oesophageal cancer
