14 Distal GI tract pathology Flashcards by Catherine Leung

Define diarrhoea.

Diarrhoea= a symptom

Loose/watery stools > 3 times a day

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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

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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

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Give some causes of secretory and osmotic diarrhoea.

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What is constipation defined as?

One of the following:

Hard stools
Difficulty passing stools
Inability to pass stools

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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

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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

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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

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How is constipation treated?

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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

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The appendix has potentially different locations which are important to consider when thinking about the presentation of acute appendicitis. Fill in the missing labels:

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What are the 3 broad categories for appendicitis? How is appendicitis caused?

Acute (mucosal oedema)

Gangrenous (transmural inflammation and necrosis)

Perforated

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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

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Why is harder to diagnose children with appendicitis?

History is difficult

Symptoms more non-specific

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What are the signs of appendicitis? What is McBurney’s point?

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How is appendicitis diagnosed?

History/examination
Blood test- WBC
Pregnancy test/urine dip- rule out pregnancy/UTI
Possibly CT with contrast

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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)
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)
1. 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)