14 - Distal GI Pathology Flashcards
What is diarrhoea?
Loose and/or regular stools more than 3 times a day
- 99% of ingested fluid and gut secretions are reabsorbed but if there is a disturbance to this it causes diarrhoea
- Acute up to two weeks
How can bacteria cause diarrhoea in simple terms?
Unwanted substance increases secretions and increases gut motility. Colon overwhelmed so cannot reaborbed all water
What are the two different categories of diarrhoea?
- Secretory: electrolyte transport abnormalities. Too much secretion of anions e.g Cl due to pertussis, or too little Na reabsorption due to mucosal disease or reduced contact time. Often due to infection
- Osmotic: presence of osmotically active but poorly absorbed substance, e.g ingested antacids like magnesium sulfate or lactose in lactase deficiency. Will settle if you remove offending agent
What is peristaltic rush?
Type of secretory diarrhoea
What is constipation?
When you have to strain, pass hard stools, are unable to pass a bowl movement or incomplete evacuation. Fewer than three unassisted bowel movements a week
What are some risk factors for conspitation
- Female
- Medications like codeine
- Low levels of physical activity
- Child under 4 or old age
What are some of the causes of constipation?
Primary: normal transit constipation, slow transit constipaytion, evacuation disorder
Secondary: medications, physical obstruction, metabolic/endocrine disorders, myopathic and neurological disorders
How can we treat constipation?
- Psychological support
- Increased fluid intake
- Increase active
- Increase dietary fibre
- Laxatives: osmotic (MgSO4 and disaccharides), stimulatory (Cl channel activators) and stool softeners
What are the different classifications of acute appendicitis?
- Acute (mucosal oedema)
- Gangrenous (transmural inflammation and necrosis)
- Perforated (peritonitis)
What is the appendix, and why is it important to know the anatomical position of the appendix?
Diverticulum of the caecum with complete longitiduninal layer of muscle externally. Separate blood supply to caecum from mesoappendix from ileocolic branch of SMA
Location important as changes presentation of acute appendicitis as may not necessarily touch parietal peritoneum, e.g pelvic pain, rectal pain
What is the cause of appendicitis?
Obstruction of the appendiceal lumen by faecolith or lymphoid hyperplasia.
Obstruction causes intraluminal pressure in appendix to rise, blocking arterial supply so ischaemia
Ischaemia allows bacterial to invade the wall and necrose or perforate
Could also be due to bacterial or viral infection changing mucosa of the appendix so bacteria can more easily infiltrate
What is the classic presentation of appendicitis (60% of cases)
- Poorly localised peri-umbilical pain due to visceral pain fibres
- Anorexia
- Nausea/Vomiting
- Low grade fever and tachycardia
- 12-24 hours later pain in right iliac fossa as appendix touches parietal peritoneum
- Rebound tenderness at McBurney’s point
- Lie quite still as peritoneum inflammed
What is McBurney’s point?
How do we diagnose and treat appendicitis?
Diagnose:
- Blood tests for raised WBC
- History/Examination especially if rebound tenderness
- Pregnancy and UTI check
- In non-classical presentation maybe CT where appendiz doesn’t fill we contrast
Treat:
- Open or laprascopic appendicectomy
What is diverticulosis?
- Asymptomatic and most common abnormality on colonoscopy, mostly in sigmoid as area where greatest pressure needed
- Most of pseduodiverticula where mucosa and submucosa herniare through external muscle layers of the colon
- Occur at sites of major branches of the vasa recta, 3-10mm and can be hundreds
What is diverticulitis?
- Inflammation and or infection of the diverticula
- Similar pathophysiology to appendicitis, entrance to diverticula blocked by faeces, inflammation allows bacterial inflammation of diverticula wall, can lead to perforation
- Can turn complicated and lead to large abscesses, perforation and fistulas
What is diverticular disease?
When a patient experiences pain with no inflammation/infection of the diverticula
What are the signs and symptoms of acute diverticulitis?
How can we diagnose and treat acute diverticulitis?
Diagnose:
- Blood test for raised WBC
- CT scan
- Elective colonoscopy, dont want to cause more bleeding
- Ultrasound
- Pregnancy test
Treat:
- Antibiotics, fluid resus and analgesia
- Surrgery if perforation or large abscess
What is the anatomy of the rectume?
- Curved shape anterior to sacrum
- Parts are extra-peritoneal
- Temporarily stores faeces and stretching stimulates urge to defecate
What is the blood supply and drainage of the rectum?
Where does the anal canal start?
- Proximal border of anal sphincter complex
- Puborectal sling cause rectum to go from being anterior to anal canal being posterior. Helps continence
What factors are needed to maintain fecal continence?
What is the anal sphincter complex made up of?
Internal involuntary sphincter: thickening of smooth circular muscle. Autonomical control, 80% continence
External striated sphincter: three layers of muscle supplied by pudendal nerve. 20% of continence
What is the defecation reflex and what are the possible consequences of this reflex?
Faeces moves into anal canal to see if appropriate to be expelled
What is the dentate line of the anal canal, and what is the relevance of this?
- Junction of hindgut and proctodaeum
- Above is visceral and columnar so doesn’t feel pain unless stretch
- Below is somatic and stratified sqaumous
What are anal cushions?
- Venous plexus divided into three areas
- Swell to help continence
- When enlarged this is haemorrhoids
What are internal haemorrhoids and how are they treated?
- Above dentate line* and covered in transitional or columnar mucosa
- Produce symptoms when lose CT support and prolapse through anal canal
- Painless until prolapse and then may bleed bright red or itch
Treat: increase hydration, fibre, avoid straining, rubber band ligation, surgery. INITIALLY SOFTEN STOOL
What are external haemorrhoids and how are they treated?
- Visible at anal verge and often residual skin from previous episodes of haemorrhoid inflammation
- Usually asymptomatic and no bleeding but symptoms when thrombosis
- Patient often has issues with hygiene due to folds of skin, itching and inflammation
What is an anal fissure, what are the causes and how do we treat it?
- Linear tear in anoderm, usually after a large hard bowel movement.
- Extremely painful when trying to pass further stools
- Patient may have bleeding
- Treat by increasing fibre and water intake, hygeine and comfort
What is haematochezia?
- High flow bleeding from upper GI or lower GI bleeding so bright red blood in stools
- Diverticulitis is most comon cause but can also be caused by polyps, cancer, colitis, anorectal disorders
What is melaena?
- Black tarry stools that are offensive smelling. Due to Hb being altered by digestive enzymes and gut bacteria
What is the pain associated with gallstones called?
- Biliary colic , no inflammation
- Pain after eating as lipids stimulate CCK release so gallbladder contracts. Can still get bile from liver though
- Pain in right
How does alcoholic fatty liver disease occur?
- Increased TAG deposits as lack of lipoproteins to carry fats and increased NADH prevents fats being metabolised
Why can alcohol misuse lead to malnutrition and vitamin deficiencies?
- Lack of appetite
- Liver damage so no vitamin synthesis
- Alcoholic pancreatitis
- Gatritis
