Why does an immunochemical faecal occult blood test (FIT) detect bleeding from the stomach poorly?

Globin is digested on the way down the gut

Upper gut blood is too dilute to detect

Haem from the stomach is absorbed in the ileum

Gastric acid destroys the antibody in the kit

What does the mixed antiglobulin reaction (MAR) test on semen detect?

Antisperm antibodies bound to the sperm

Leukocytes among the round cells

Fructose secreted by the seminal vesicles

Clinical pathology: faeces, sputum and semen

34 Kerala MSc MLT Entrance practice questions on Clinical pathology: faeces, sputum and semen, part of Pathology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Easy
Which pigment mainly gives faeces their normal brown colour?
1. AConjugated bilirubin
2. BBiliverdin
3. CUrobilinogen
4. DStercobilin
Show answerHide answer
Answer: D · Stercobilin
Gut bacteria convert bilirubin to urobilinogen, which is oxidised in the colon to the brown pigment stercobilin. When bile cannot reach the gut, as in obstructive jaundice, stools become pale or clay-coloured. Green stools can contain unchanged biliverdin in rapid transit. Urobilinogen itself is colourless.
- A: Conjugated bilirubin is converted by gut bacteria and is not the stool pigment.
- B: Biliverdin is green and is seen mainly in rapid transit.
- C: Urobilinogen is colourless until oxidised.
Question 2 · Medium
Why does an immunochemical faecal occult blood test (FIT) detect bleeding from the stomach poorly?
1. AGlobin is digested on the way down the gut
2. BUpper gut blood is too dilute to detect
3. CHaem from the stomach is absorbed in the ileum
4. DGastric acid destroys the antibody in the kit
Show answerHide answer
Answer: A · Globin is digested on the way down the gut
FIT uses antibodies against human globin. Globin from blood lost in the stomach or duodenum is broken down by digestive enzymes before it reaches the stool, so the test responds mainly to colorectal bleeding. This makes it suited to colorectal cancer screening. Guaiac tests detect haem, which survives digestion better.
- B: The key reason is digestion of globin, not dilution.
- C: Haem is not removed in a way that explains the result; globin breakdown does.
- D: The kit antibody never meets gastric acid; the reaction is done on stool.
Question 3 · Hard
A stool sample is offensive, dark red, with blood mixed in, and acid in reaction. Microscopy shows red cells in clumps, few pus cells and Charcot-Leyden crystals. What is the most likely diagnosis?
1. AAmoebic dysentery
2. BBacillary dysentery
3. CGiardiasis
4. DCholera
Show answerHide answer
Answer: A · Amoebic dysentery
Amoebic dysentery gives an offensive, dark red stool with blood mixed with faeces, an acid reaction, clumped red cells, scanty pus cells and Charcot-Leyden crystals; trophozoites with ingested red cells confirm it. Bacillary dysentery gives an odourless, bright red, alkaline stool with many pus cells and macrophages and discrete red cells. Cholera gives rice-water stools without blood. Giardiasis gives pale, fatty stools without blood.
- B: Bacillary dysentery shows many pus cells and macrophages and an alkaline reaction.
- C: Giardiasis gives greasy stools without blood or crystals.
- D: Cholera gives watery rice-water stools without blood.
Question 4 · Medium
What does the mixed antiglobulin reaction (MAR) test on semen detect?
1. AAntisperm antibodies bound to the sperm
2. BLeukocytes among the round cells
3. CSperm that are dead but intact
4. DFructose secreted by the seminal vesicles
Show answerHide answer
Answer: A · Antisperm antibodies bound to the sperm
In the MAR test, fresh semen is mixed with latex beads or red cells coated with human IgG (or IgA) and anti-human globulin. If antibodies coat the motile sperm, the beads stick to them and move with them. Binding to many motile sperm suggests immunological infertility. Sperm agglutination in the wet preparation is a clue to request it.
- B: Leukocytes are identified by a peroxidase stain.
- C: Dead sperm are identified by an eosin-nigrosin vitality stain.
- D: Fructose is measured chemically.
Question 5 · Easy
By the WHO manual, 6th edition (2021), the lower reference limit for sperm concentration is about:
1. A16 million/mL
2. B40 million/mL
3. C20 million/mL
4. D5 million/mL
Show answerHide answer
Answer: A · 16 million/mL
The WHO 6th edition gives lower reference limits (5th centiles) from fertile men: volume 1.4 mL, concentration 16 million/mL, total count 39 million per ejaculate, total motility 42%, progressive motility 30% and normal forms 4%. Older editions used higher cut-offs, such as 20 million/mL. Values below the limit are not proof of infertility. Two samples are examined before a conclusion is drawn.
- B: About 39-40 million is the limit for total count per ejaculate, not concentration.
- C: 20 million/mL is an older WHO cut-off.
- D: 5 million/mL is far below the reference limit and marks severe oligozoospermia.
Question 6 · Hard
A 28-year-old man with chronic sinusitis and bronchiectasis gives semen at the laboratory. At 30 minutes: concentration 45 million/mL, total motility 3%, no agglutination, eosin-nigrosin 78% live. The most likely cause is:
1. ANecrozoospermia
2. BLeukocytospermia from infection
3. CPrimary ciliary dyskinesia
4. DRetrograde ejaculation
Answer and explanation in LearnFree account
Question 7 · Hard
Semen analysis: volume 2.0 mL, concentration 30 million/mL, progressive motility 40%, non-progressive motility 10%. What is the total number of progressively motile sperm in the ejaculate?
1. A60 million
2. B12 million
3. C30 million
4. D24 million
Answer and explanation in LearnFree account
Question 8 · Medium
A patient with high fever and chest pain coughs up rusty-brown sputum. What does this most suggest?
1. AAcute pulmonary oedema
2. BKlebsiella pneumonia
3. CPneumococcal lobar pneumonia
4. DRupture of an amoebic liver abscess
Answer and explanation in LearnFree account
Question 9 · Medium
A semen sample has a normal volume, concentration and motility, but only 2% normal forms by strict criteria. This is termed:
1. ANecrozoospermia
2. BTeratozoospermia
3. COligozoospermia
4. DAsthenozoospermia
Answer and explanation in LearnFree account
Question 10 · Easy
Coiled mucus casts of the small bronchioles, seen in the sputum of asthmatic patients, are called:
1. ACreola bodies
2. BCurschmann spirals
3. CDittrich plugs
4. DCharcot-Leyden crystals
Answer and explanation in LearnFree account
Question 11 · Easy
What is the lower reference limit for the pH of normal semen in the WHO manual?
1. A5.5
2. B8.5
3. C7.2
4. D6.5
Answer and explanation in LearnFree account
Question 12 · Easy
Black, sticky, tarry stools (melaena) most often indicate bleeding from the:
1. AUpper gastrointestinal tract
2. BDescending colon
3. CRectum and anal canal
4. DUrinary bladder
Answer and explanation in LearnFree account
Question 13 · Hard
A 38-year-old man with long-standing type 1 diabetes and peripheral neuropathy gives a semen sample of 0.3 mL. It contains no sperm after centrifugation, and fructose is present. A urine sample passed just after ejaculation contains many sperm. What is the most likely diagnosis?
1. AEjaculatory duct obstruction
2. BNon-obstructive azoospermia
3. CRetrograde ejaculation
4. DIncomplete collection of semen
Answer and explanation in LearnFree account
Question 14 · Medium
A man treated for an amoebic liver abscess suddenly coughs up a large amount of reddish-brown sputum like anchovy sauce. What has most likely happened?
1. AThe abscess has ruptured into a bronchus
2. BHe has developed pneumococcal pneumonia
3. CHe has developed acute pulmonary oedema
4. DHe has a pulmonary infarct from an embolus
Answer and explanation in LearnFree account
Question 15 · Hard
A 30-year-old man with long-standing asthma has worsening wheeze and coughs up brown, rubbery plugs. Total serum IgE is 2,400 IU/mL (reference below 100). Sputum shows many eosinophils, Charcot-Leyden crystals and septate hyphae branching at acute angles. The most likely diagnosis is:
1. APulmonary mucormycosis
2. BUncomplicated bronchial asthma
3. CInvasive pulmonary aspergillosis
4. DAllergic bronchopulmonary aspergillosis
Answer and explanation in LearnFree account
Question 16 · Easy
Copious purulent sputum that separates into three layers on standing in a glass jar is typical of:
1. ABronchial asthma
2. BLobar pneumonia
3. CPulmonary oedema
4. DBronchiectasis
Answer and explanation in LearnFree account
Question 17 · Hard
A 50-year-old man with heavy alcohol use had an episode of vomiting while drunk two weeks ago. He now has fever and coughs up large amounts of foul-smelling purulent sputum. A KOH preparation shows elastic fibres, and the Gram stain shows many neutrophils with mixed Gram-positive and Gram-negative flora. The most likely diagnosis is:
1. APneumococcal lobar pneumonia
2. BAllergic bronchial asthma
3. CAspiration lung abscess
4. DAcute pulmonary oedema
Answer and explanation in LearnFree account
Question 18 · Medium
Stool microscopy of which diarrhoeal illness usually shows no pus cells?
1. ACampylobacter enteritis
2. BUlcerative colitis
3. CShigellosis
4. DCholera
Answer and explanation in LearnFree account
Question 19 · Medium
On a wet preparation of semen, motile sperm are seen stuck to each other head to head. This finding is called agglutination and suggests:
1. AProstatic infection
2. BAntisperm antibodies
3. CExcess abstinence
4. DDelayed liquefaction
Answer and explanation in LearnFree account
Question 20 · Hard
A 64-year-old woman has haemoglobin 9.0 g/dL (reference 12-15 g/dL), MCV 70 fL and a low ferritin. She takes 1 g of vitamin C daily. Guaiac tests on three stool samples are negative. What is the most appropriate next step?
1. AAsk for a single random stool for guaiac testing
2. BRepeat the guaiac test after a red meat diet
3. CReport that gastrointestinal blood loss is excluded
4. DRepeat the testing with an immunochemical test (FIT)
Answer and explanation in LearnFree account
Question 21 · Medium
Freshly ejaculated semen clots and then liquefies within about 15-30 minutes. Which enzyme brings about this liquefaction?
1. AAcid phosphatase
2. BNeutral alpha-glucosidase
3. CHyaluronidase
4. DProstate-specific antigen
Answer and explanation in LearnFree account
Question 22 · Medium
In the Sudan stain for faecal fat, a second slide is heated with acetic acid before staining. What is the purpose of this step?
1. ATo kill parasites and bacteria before microscopy
2. BTo fix the stool proteins so that they do not take the stain
3. CTo convert soaps and fatty acids to stainable free fatty acids
4. DTo dissolve the neutral fat so that only split fat remains
Answer and explanation in LearnFree account
Question 23 · Hard
A semen smear is stained for peroxidase. In the fields in which 400 sperm are counted, 20 peroxidase-positive cells are seen. The sperm concentration is 40 million/mL. What is the leukocyte concentration, and is it raised?
1. A2.0 million/mL, raised
2. B8.0 million/mL, raised
3. C0.2 million/mL, normal
4. D0.5 million/mL, normal
Answer and explanation in LearnFree account
Question 24 · Medium
In the hypo-osmotic swelling (HOS) test, the tails of some sperm swell and coil after mixing with a hypo-osmotic solution. These sperm are:
1. AImmature germ cells
2. BDead, with leaking membranes
3. CAlive, with intact membranes
4. DCoated with antibody
Answer and explanation in LearnFree account
Question 25 · Hard
A 2-day-old breastfed baby passes a stool with fresh blood. The mother has cracked, bleeding nipples. The bloody material is mixed with water and centrifuged; when 1% sodium hydroxide is added, the pink supernatant turns yellow-brown within 2 minutes. What does this show?
1. AThe baby has a haemoglobinopathy
2. BThe blood is from the baby's own gut
3. CThe blood is swallowed maternal blood
4. DThe test is invalid without a control
Answer and explanation in LearnFree account

9 more Clinical pathology: faeces, sputum and semen questions

Answer them one by one, keep your score and see your weak topics in Learn. Signed-out visitors try 25 per exam; sign in with Google to see them all.

Study Pathology

Clinical pathology: faeces, sputum and semen

Which pigment mainly gives faeces their normal brown colour?

Why does an immunochemical faecal occult blood test (FIT) detect bleeding from the stomach poorly?

A stool sample is offensive, dark red, with blood mixed in, and acid in reaction. Microscopy shows red cells in clumps, few pus cells and Charcot-Leyden crystals. What is the most likely diagnosis?

What does the mixed antiglobulin reaction (MAR) test on semen detect?

By the WHO manual, 6th edition (2021), the lower reference limit for sperm concentration is about:

A 28-year-old man with chronic sinusitis and bronchiectasis gives semen at the laboratory. At 30 minutes: concentration 45 million/mL, total motility 3%, no agglutination, eosin-nigrosin 78% live. The most likely cause is:

Semen analysis: volume 2.0 mL, concentration 30 million/mL, progressive motility 40%, non-progressive motility 10%. What is the total number of progressively motile sperm in the ejaculate?

A patient with high fever and chest pain coughs up rusty-brown sputum. What does this most suggest?

A semen sample has a normal volume, concentration and motility, but only 2% normal forms by strict criteria. This is termed:

Coiled mucus casts of the small bronchioles, seen in the sputum of asthmatic patients, are called:

What is the lower reference limit for the pH of normal semen in the WHO manual?

Black, sticky, tarry stools (melaena) most often indicate bleeding from the:

A 38-year-old man with long-standing type 1 diabetes and peripheral neuropathy gives a semen sample of 0.3 mL. It contains no sperm after centrifugation, and fructose is present. A urine sample passed just after ejaculation contains many sperm. What is the most likely diagnosis?

A man treated for an amoebic liver abscess suddenly coughs up a large amount of reddish-brown sputum like anchovy sauce. What has most likely happened?

A 30-year-old man with long-standing asthma has worsening wheeze and coughs up brown, rubbery plugs. Total serum IgE is 2,400 IU/mL (reference below 100). Sputum shows many eosinophils, Charcot-Leyden crystals and septate hyphae branching at acute angles. The most likely diagnosis is:

Copious purulent sputum that separates into three layers on standing in a glass jar is typical of:

Stool microscopy of which diarrhoeal illness usually shows no pus cells?

On a wet preparation of semen, motile sperm are seen stuck to each other head to head. This finding is called agglutination and suggests:

A 64-year-old woman has haemoglobin 9.0 g/dL (reference 12-15 g/dL), MCV 70 fL and a low ferritin. She takes 1 g of vitamin C daily. Guaiac tests on three stool samples are negative. What is the most appropriate next step?

Freshly ejaculated semen clots and then liquefies within about 15-30 minutes. Which enzyme brings about this liquefaction?

In the Sudan stain for faecal fat, a second slide is heated with acetic acid before staining. What is the purpose of this step?

A semen smear is stained for peroxidase. In the fields in which 400 sperm are counted, 20 peroxidase-positive cells are seen. The sperm concentration is 40 million/mL. What is the leukocyte concentration, and is it raised?

In the hypo-osmotic swelling (HOS) test, the tails of some sperm swell and coil after mixing with a hypo-osmotic solution. These sperm are:

A 2-day-old breastfed baby passes a stool with fresh blood. The mother has cracked, bleeding nipples. The bloody material is mixed with water and centrifuged; when 1% sodium hydroxide is added, the pink supernatant turns yellow-brown within 2 minutes. What does this show?