14 Distal GI tract pathology Flashcards
Define diarrhoea.
Diarrhoea= a symptom
Loose/watery stools > 3 times a day
In general terms, how might diarrhoea be caused? (2) What are the two broad categories for diarrhoea ( relate to the causes)
- Unwanted substance- gut motility and secretions stimulated to get rid of it (primarily secretion)
- Colon overwhelemed- cannot receive quantity of water from ileum
Categories:
- Osmotic
- Secretory
Which types of diarrhoea (osmotic or secretory) stops when fasting? Explain why?
Osmotic - presence of electrolytes and nutrients in bowel lumne draws water in. If nothing there to pull water in diarrhoea will stop.
Secretory- diarrhoea will continue
Give some causes of secretory and osmotic diarrhoea.
What is constipation defined as?
One of the following:
- Hard stools
- Difficulty passing stools
- Inability to pass stools
What are some risk factors for constipation? (4)
- Medication eg codeine
- Female:male 3:1
- Increasing age/ children under 4 years
- Low level of physical activity
How is material usually moved through the large intestine during fasting and during digestion?
- Fasting: shuttle contractions- facilitate absorptive process
- Digestion: mass peristalsis–> propulsive waves- mass movement towards rectum for defaecation
What are the 3 main classes of constipations (according to physiological cause)?
Normal transit constipation
eg harder stools
Slow transit constipation
decreased bowel movement
Defaecation problems: pelvic floor dysfunction
How is constipation treated?
Describe the structure of the appendix? (inc blood supply)
Appendix= diverticulum off caecum
Has complete longitudinal layer of muscle
Separate blood supply to caecum- coming up through mesentery from ileocolic branchc of SMA
The appendix has potentially different locations which are important to consider when thinking about the presentation of acute appendicitis. Fill in the missing labels:
What are the 3 broad categories for appendicitis? How is appendicitis caused?
Acute (mucosal oedema)
Gangrenous (transmural inflammation and necrosis)
Perforated
What are the symptoms of appendicitis? Why might pain experienced be different in someone who has a pelvic or a retrocaecal appendix?
Remember: altered anatomy in pregnancy
Why is harder to diagnose children with appendicitis?
History is difficult
Symptoms more non-specific
What are the signs of appendicitis? What is McBurney’s point?
How is appendicitis diagnosed?
- History/examination
- Blood test- WBC
- Pregnancy test/urine dip- rule out pregnancy/UTI
- Possibly CT with contrast
How is appendicitis treated?
Antibiotics
Open appendicectomy
Laparoscopic appedicectomy
What is diverticulosis, where do the majority occur and how is it caused?
Is it symptomatic?
Where?
Colon- 85% sigmoid colon
Where nutrient vessels penetrate bowel wall
Symptomatic?
Asymptomatic
What is the difference between diverticular disease and acute diverticulitis?
Diverticular disease= patient experiences pain but there is no inflammation/infection
Diverticulitis= diverticula are inflammed/perforate +/- bleeding and abscess formation
In what % of people with diverticulosis does diverticulitis occur? How does diverticulitis occur?
25%
Differentiate between complicated and uncomplicated diverticulitis:
Uncomplicated- inflammation and small absecesses confined to colonic wall
Complicated- larger abscesses, fistulas, perforation
What are the signs and symptoms of acute diverticulitis?
- Symptoms
- Abdominal pain at site of inflammation
- usually left lower quadrant- sigmoid colon)
- Fever
- Bloating
- Constipation (inflammation can block colonic lumen)
- Haematochezia (fresh blood- not malaena)
- Abdominal pain at site of inflammation
- Signs
- Tachycardia
- Abdominal distension
- Localised abdominal tenderness
- Reduced bowel sounds
- Signs of peritonitis eg nausea/vomiting
How is acute diverticulitis investigated?
Blood tests- raised WBCs
Pregnancy test- exclude ectopic
Ultrasound
CT scan
Colonoscopy (BUT be careful not to cause perforation)
How is acute diverticulitis treated? (think uncomplicated and complicated)
- Antibiotics, fluids, analgesia (may be sufficient for uncomplicated)
- Surgery if perforation/large abscess (-needs to be drained)
- Partial colectomy required if other treatments failed
Describe the structure of the rectum and its function. What stimulates the urge to defaecate?
Structure:
- 12-15cm
- Continuous band of outer longitudinal muscle (unlike teniae coli of rest of colon)
- Curved shaped, anterior to sacrum
- Parts= intraperitoneal and parts= extraperitoneal
Function:
- Temporary storage of faeces prior to defecation
- Stretching of rectum stimulates urge to defaecate
The blood supply to the rectum is from 3 main arteries that form a plexus. Where do these 3 main arteries branch off?
- Superior rectal artery
- Middle rectal artery
- Inferior rectal artery
- Superior rectal artery- inferior mesenteric
- Middle rectal artery- internal iliac
- Inferior rectal artery- pudendal artery
Describe the venous drainage of the rectum.
- Portal drainage- superior rectal vein
-
Systemic drainage- internal iliac vein
- Potential for porto-systemic anastamosis
Where is the start of the anal canal? Does it point anteriorly or posteriorly?
Fill in the missing labels:
What makes up the anal sphincter complex? What type of muscle is it?
Outline how defecation occurs. (defecation reflex, delay/defecation)
The dentate (pectinate) line is the junction between which parts embryologically? What is it the division between (type of pain receptors and type of epithelium)?
Junction of hindgut and proctodaeum (ectoderm)
What are haemorrhoids (not necessarily pathological)?
Anal cushions= venous plexus areas
Play role in anal continence
Haemorrhoids can be pathological- they are either internal or external. How might internal haemorrhoids (above dentate line) be caused and how do they present?
- How?
- Loss of connective tissue support
- Presentation?
- Relatviely painless
- Can enlarge and prolapse through anal canal
- Can bleed bright red blood
- Pruritis (skin itching)
How are internal haemorrhoids treated?
- Increased hydration/high fibre diet
- Avoid straining
- Rubber band ligation
- Surgery
What are the different grades of internal haemorrhoids?
Are external haemorrhoids painful? How are they treated?
Very painful- contains blood clot
Surgery (to treat thrombosed external haemorrhoids)
What is an anal fissure? How can is present?
Linear tear in anoderm
Usually posterior midline
After passing hard stool (but not necessarily)
- Very painful defaecation
- Haematochezia
How are anal fissures caused (risk factors) (2)? How are anal fissures treated?
Causes/risk factors:
- High internal anal sphincter tone
- Reduced blood flow to anal mucosa
Treatment:
- Hydration, dietary fibre, analgesia
- Warm baths
- Medication (try and relax anal sphincter)
What are some causes of haematochezia?
- Diverticulitis
- Angiodysplasia (small vascular malformation in bowel wall)
- Colitis (IBD, infective)
- Colorectal cancer
- Anorectal disease
Give some causes of malaena:
(offensive smelling- haemoglobin altered by digestive enzymes and gut bacteria)
