Distal GI tract pathology Flashcards
What is diarrhoea?
loose or frequent passing of stools more than 3 times a day
What is the pathophysiology of diarrhoea?
- unwanted substances in the gut stimulate secretion and motility to get rid of it
- more down to the epithelial function rather than increased gut motility (although that can occur-colon becomes overwhelmed and can’t absorb the quantity of water it receives from the ileum
What happens in the gut with regards to water etc?
water is not actively moved across the gut, it follows the osmotic forces generated by the movement of electrolytes and nutrients
What is osmotic diarrhoea?
- the gut lumen contains too much osmotic material (malabsorption)
- not enough has been absorbed into tissues so remains inside the ileum and moved into the colon so water will follow it
- if you stop injesting the cause, it will relieve itsefl
What is secretory diarrhoea?
Electrolyte tranport is imparied and too much secretion of ions (cl- and HCO3-) e.g. cholera
- also have too little absorption of Na+ caused by 1) reduced surface area for absorption
2) mucosal disease like IBD or coelia
3) reduced contact time AKA intestinal rush causing by diabetes
What is constipation?
hard stools, difficulty passing stools or inability to pass stools
- straining
- imcomplete evacutation
- fewer than 3 unassisted bowel movements a week
What are the risk factors of constipation?
- female (3:1) compared to male
- certain medications (codeine)
- low levels of physical activity
- increasing age but also children under 4 (need to on laxatives for years)
What is the pathophysiology of constipation?
1) normal transit constpation typically due to psychological signs like anxiety
2) slow colon transport caused by;
- hypthyroidism
- diabetes
- large colong (megacolon)
- fewer peristaltic movements and shorter ones
- nervouse system disease like Parkinson’s or MS
3) defection problems so you can’t coordinate the muscles of defection or the pelvic floor or anorectum
What are the treatments for constipation?
- psychological support
- increased fluid intake
- increased activity
- increased dietary fibre mild
- fibre medication
- laxatives (osmotic - MgSO4 or secretory chloride channel activators)
What is the appendix and what is its blood supply?
- midgut structure
- it is a diverticulum off the caecum and has a complete longitudinal layer of muscle (colon has incomplete bands)
- blood supply is different to caecum as it has the blood supply travelling in the mesentery from the ileocolic branch of the SMA
Where is the appendix?
RLQ EITHER -retrocaecal -pelvic -sub-caecal -para-ileal
-depending of where the appendix lies (can be in different positions) depends on position of pain felt, may not necessarily be RLQ pain as could be rectal, pelvic etc
What are the categories of appendicitis?
- acute caused by mucosal oedema
- gangrenous (necrosis)
- perforated
What are the causes of appendicitis?
1) blockage of the appendices lumen - can cause stasis- creates a higher pressure in the appendix causing venous pressure to rise causing oedema making it harder for arterial blood to supply appendix causing ischaemia in the walls of the appendix and bacterial invasion will follow
-can be caused by lymphoid metaplasia
OR
2) viral or bacterial infection causes mucosal changes that allow bacterial invasion of the appendices wall
What are the symptoms of appendicitis?
- poor localised peri-umbilical pain
- anorexia
- nausea and vomiting
- low grade fever
- after 12-24 hours, pain will be felt in the right iliac fossa
Why would you get peri-umbilical pain?
- mid gut structure
- appendix will stretch when inflamed
- mid-gut refers pain back to the T10 dermatome
Why does pain reach the right iliac fossa?
-due to inflamed appendix touching parietal peritoneum which localises the pain to the RIF
Where would you get pain is the appendix is retro-caecal or pelvic?
- supra-pubic pain
- right sided rectal pain
- vaginal pain
NOT RIF as in this case the appendix would not touch the parietal peritoneum
When else would the pain change its location in appendicitis?
-pregnancy due to changed anatomy
What are the signs or appendicitis?
- patients appear slightly ill
- slight fever and tachycardia
- will lie quite still
- localised RLQ tendernedd
- rebound tenderness in right iliac fossa (mcburneys point (2/3 way from umbilicus to ASIS))
How is appendicitis diagnosed?
- FBC (raised WBC)
- rebound tenderness
- pregnancy test to rule out pregnancy and UTI
- CT scan (for unclassic symptoms) will show distended appendix that doesn’t fill with contrast
What is the treatment for appendicitis?
- open appendicectomy
- laproscopic appendicectomy
What is diverticulosis?
Outpouchings of the mucosa and submucosa that herniate through the muscular layers
When does diverticulosis occur?
along where the nutrient vessels penetrate the bowel wall in the colon (especially sigmoid) - weaknesses
What symptoms do you get with diverticulosis?
asymptomatic
Why is the sigmoid colon prone to diverticulars?
- sigmoid bit has more formed stools so pressure to move the stool causing weakness areas (where nutrient arteries penetrate in) to allow colon through
What is diverticular disease?
-when you have diverticular and pain but no inflammation
What is acute diverticulitis?
- diverticulars in the colon with pain AND inflammation
- can have bleeding or abscess formation too
