Unit 1: Alimentary and digestive system pathology
Basic Cellular Pathology notes · PTU syllabus (BMLS401-18)
On this page
- Unit summary
- Diseases of the mouth and salivary glands
- Oesophageal varices, gastritis and peptic ulcer
- Appendicitis, infections and food poisoning
- Hernia, intestinal obstruction and malabsorption
- Hepatitis
- Cirrhosis and liver failure
- Pancreatitis and gallstones
- Jaundice
- Key terms
- Quick revision
- Important questions
Unit summary
Diseases of the digestive tract and its glands are common reasons for laboratory testing. This unit covers diseases of the mouth, oesophageal varices, gastritis, peptic ulcer, appendicitis, intestinal infections and food poisoning, hernia, obstruction and malabsorption, mumps, hepatitis, liver failure, cirrhosis, pancreatitis, gallstones and jaundice.
After this unit you can
- Describe diseases of the mouth, oesophagus and stomach
- Describe intestinal diseases and malabsorption
- Describe hepatitis, cirrhosis and liver failure
- Classify jaundice and describe pancreatic and gall bladder disease
PTU syllabus topics
- Diseases of the mouth
- oesophageal varices
- gastritis
- peptic ulceration
- appendicitis
- microbial diseases
- food poisoning
- hernia
- intestinal obstruction and malabsorption
- salivary gland diseases (mumps)
- hepatitis
- liver failure
- cirrhosis
- pancreatitis
- gall stones
- jaundice
Pre-hepatic (haemolytic)
Excess breakdown of red cells
Raised unconjugated bilirubin; urine urobilinogen up
Hepatic
Liver cell damage, e.g. hepatitis
Both bilirubins raised; ALT and AST high
Post-hepatic (obstructive)
Blocked bile flow, e.g. gallstones
Raised conjugated bilirubin; ALP high; pale stools
Topic 1
Diseases of the mouth and salivary glands
- Dental caries
- Acid from bacteria (Streptococcus mutans) dissolves enamel
- Periodontitis
- Gum infection loosening teeth
- Oral candidiasis (thrush)
- White patches; immunosuppression
- Leukoplakia and oral cancer
- White patches; tobacco chewing a major cause in India
- Mumps
- Paramyxovirus; painful parotid swelling; complications orchitis, pancreatitis, meningitis; raised serum amylase
Topic 2
Oesophageal varices, gastritis and peptic ulcer
Oesophageal varices
Dilated veins from portal hypertension (cirrhosis)
Massive vomiting of blood; low Hb
Gastritis
H. pylori, NSAIDs, alcohol, autoimmune
Epigastric pain; autoimmune type causes pernicious anaemia
Peptic ulcer
H. pylori (most), NSAIDs; acid imbalance
Burning pain; bleeding (stool occult blood); urea breath test, stool antigen, biopsy urease test
Topic 3
Appendicitis, infections and food poisoning
- Appendicitis: obstruction and infection of the appendix; right lower abdominal pain; leucocytosis with neutrophilia; risk of perforation.
Bacterial diarrhoea and dysentery
E. coli, Shigella, Salmonella, Campylobacter, V. cholerae
Stool microscopy (pus cells), culture
Food poisoning (toxin)
S. aureus and B. cereus (1–6 hours), C. perfringens (8–16 hours), C. botulinum
Food and stool testing
Parasitic
Giardia, Entamoeba histolytica, worms
Stool ova and cyst examination
Viral
Rotavirus, norovirus
Antigen tests
Topic 4
Hernia, intestinal obstruction and malabsorption
- Hernia: protrusion of an organ through a weak wall (inguinal, umbilical, hiatus); risk of strangulation.
- Intestinal obstruction: adhesions, hernia, tumours, volvulus, intussusception; vomiting, distension, constipation; electrolyte loss.
- Malabsorption: coeliac disease (gluten; anti-tTG antibodies), chronic pancreatitis, lactose intolerance, tropical sprue — steatorrhoea, weight loss, anaemia; tests include faecal fat and D-xylose absorption.
Topic 5
Hepatitis
Hepatitis A
Faecal–oral
Anti-HAV IgM
Hepatitis B
Blood, sexual, mother to child
HBsAg, HBeAg, anti-HBc IgM, HBV DNA; may become chronic
Hepatitis C
Blood
Anti-HCV, HCV RNA; often chronic
Hepatitis D
Only with B
Anti-HDV
Hepatitis E
Faecal–oral; severe in pregnancy
Anti-HEV IgM
- Liver function tests: ALT and AST markedly raised in acute hepatitis; bilirubin raised; ALP mildly raised.
Topic 6
Cirrhosis and liver failure
- Cirrhosis: irreversible fibrosis with regenerating nodules — alcohol, hepatitis B and C, fatty liver disease. Consequences: portal hypertension (varices, ascites, splenomegaly), low albumin, prolonged PT, hepatic encephalopathy (raised ammonia), liver cancer risk.
- Liver failure: acute (paracetamol overdose, viral hepatitis) or chronic; jaundice, bleeding, coma.
Topic 7
Pancreatitis and gallstones
Acute pancreatitis
Gallstones, alcohol
Serum amylase and lipase more than three times normal; high glucose; low calcium
Chronic pancreatitis
Alcohol
Steatorrhoea, diabetes, low faecal elastase
Gallstones (cholelithiasis)
Cholesterol, pigment or mixed stones
May cause obstructive jaundice; raised ALP and conjugated bilirubin
Topic 8
Jaundice
- Jaundice: yellow skin and eyes when serum bilirubin exceeds about 2–3 mg/dL (normal total below 1.2 mg/dL).
Pre-hepatic (haemolytic)
Excess red cell breakdown — haemolytic anaemia, malaria
Raised unconjugated bilirubin; urine urobilinogen raised; no bilirubin in urine
Hepatic (hepatocellular)
Hepatitis, cirrhosis, drugs
Both forms raised; ALT and AST high
Post-hepatic (obstructive)
Gallstones, carcinoma of pancreas head
Raised conjugated bilirubin; bilirubin in urine; urobilinogen absent; pale stools; ALP very high
- Neonatal jaundice: physiological (days 2–7) or pathological (Rh or ABO incompatibility, G6PD deficiency).
Key terms
- Peptic ulcer
- Erosion of the stomach or duodenal lining
- Malabsorption
- Defective absorption of nutrients
- Cirrhosis
- Irreversible fibrosis of the liver with nodules
- HBsAg
- Surface antigen marker of hepatitis B infection
- Obstructive jaundice
- Jaundice from blocked bile flow
Quick revision
- Caries, thrush, oral cancer, mumps (amylase).
- Varices, gastritis, peptic ulcer and H. pylori tests.
- Appendicitis; infective diarrhoea; food poisoning timelines; hernia, obstruction, malabsorption.
- Hepatitis A–E markers; cirrhosis; liver failure.
- Pancreatitis (amylase, lipase); gallstones; three types of jaundice.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.Name two tests for H. pylori.
- Q2.Which enzyme rises in mumps?
- Q3.Which hepatitis viruses spread by the faecal–oral route?
- Q4.What is the main marker of hepatitis B infection?
- Q5.State two features of cirrhosis.
- Q6.Distinguish haemolytic and obstructive jaundice by urine findings.
Long-answer questions
- Q1.Describe peptic ulcer and its laboratory diagnosis.
- Q2.Describe viral hepatitis and its laboratory markers.
- Q3.Describe cirrhosis and liver failure.
- Q4.Classify jaundice with laboratory findings.
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