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
