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Question 1Semen Analysis and Semen Evaluation

According to the WHO laboratory manual, which parameter is primarily used to classify a semen sample as normal or abnormal in the basic semen analysis?

  1. Sperm concentration Correct answer.
  2. Semen volume
  3. Sperm morphology
  4. Total sperm number

Explanation

The WHO manual uses sperm concentration as a key parameter for classifying semen samples, with a lower reference limit of 15 million spermatozoa per mL. While other parameters are important, concentration is central to the basic classification.

Question 2Semen Analysis and Semen Evaluation

What is the recommended lower reference limit for semen volume in the WHO 2010 manual?

  1. 1.4 mL Correct answer.
  2. 2.5 mL
  3. 1.0 mL
  4. 2.0 mL

Explanation

The WHO 2010 manual sets the lower reference limit for semen volume at 1.4 mL, based on the 5th centile of a reference population. This value is used to identify samples with low volume (hypospermia).

Question 3Semen Analysis and Semen Evaluation

During semen analysis, how long should the sample be allowed to liquefy at room temperature before assessment?

  1. 60 minutes
  2. 15 minutes
  3. 30 minutes Correct answer.
  4. 5 minutes

Explanation

Semen typically liquefies within 15–30 minutes at room temperature. The WHO recommends waiting up to 30 minutes for liquefaction before proceeding with analysis, but not exceeding 60 minutes.

Question 4Semen Analysis and Semen Evaluation

Which of the following is the correct formula for calculating sperm concentration using a Neubauer hemocytometer?

  1. Number of sperm counted × dilution factor × volume of chamber
  2. Number of sperm counted / (volume of chamber × dilution factor)
  3. (Number of sperm counted × dilution factor) / (volume of chamber × 1000) Correct answer.
  4. (Number of sperm counted × volume of chamber) / dilution factor

Explanation

Sperm concentration is calculated as the number of sperm counted multiplied by the dilution factor, divided by the volume of the counted area. The result is expressed in million per mL, often requiring a conversion factor of 1000.

Question 5Semen Analysis and Semen Evaluation

When assessing sperm motility, which category includes spermatozoa that are moving but without progressive movement?

  1. Grade b
  2. Grade c Correct answer.
  3. Grade d
  4. Grade a

Explanation

In the WHO motility grading system, grade c refers to spermatozoa with non-progressive motility, such as those moving in circles or with flagellar beating without forward progression. Grade a is rapid progressive, grade b is slow progressive, and grade d is immotile.

Question 6Semen Analysis and Semen Evaluation

Which staining method is commonly used for sperm morphology assessment according to WHO recommendations?

  1. Papanicolaou stain Correct answer.
  2. Gram stain
  3. Giemsa stain
  4. Ziehl-Neelsen stain

Explanation

The Papanicolaou stain is recommended by WHO for sperm morphology assessment because it provides clear differentiation of the acrosome, nucleus, and midpiece. Other stains like Shorr or Diff-Quik may also be used, but Papanicolaou is standard.

Question 7Semen Analysis and Semen Evaluation

What is the lower reference limit for sperm morphology (normal forms) in the WHO 2010 manual?

  1. 1%
  2. 14%
  3. 4% Correct answer.
  4. 10%

Explanation

The WHO 2010 manual sets the lower reference limit for normal sperm morphology at 4%, using strict criteria. This means that 4% or more normal forms is considered normal.

Question 8Semen Analysis and Semen Evaluation

Which of the following is a correct description of the 'strict criteria' for sperm morphology?

  1. Sperm must have an oval head with a length-to-width ratio of 1.5 to 1.75 Correct answer.
  2. Sperm must have a head length of at least 5 micrometers
  3. Sperm must have a midpiece that is twice the length of the head
  4. Sperm must have a tail length of at least 45 micrometers

Explanation

Strict criteria, as described by Tygerberg, require a normal sperm head to be oval with a length-to-width ratio of 1.5 to 1.75, among other features. This helps standardize morphology assessment.

Question 9Semen Analysis and Semen Evaluation

A semen sample has a volume of 3.5 mL and a sperm concentration of 20 million/mL. What is the total sperm number?

  1. 40 million
  2. 50 million
  3. 60 million
  4. 70 million Correct answer.

Explanation

Total sperm number is calculated by multiplying semen volume by sperm concentration: 3.5 mL × 20 million/mL = 70 million. This value is used to assess overall sperm production.

Question 10Semen Analysis and Semen Evaluation

Which pH value is considered normal for semen according to WHO reference limits?

  1. 7.2 or higher Correct answer.
  2. 7.8 or higher
  3. 8.0 or higher
  4. 6.5 or higher

Explanation

The WHO lower reference limit for semen pH is 7.2. A pH below 7.2 may indicate increased acidity, possibly due to ejaculatory duct obstruction or other abnormalities.

Question 11Semen Analysis and Semen Evaluation

During semen analysis, what does the term 'viscosity' refer to?

  1. The number of sperm per milliliter
  2. The speed at which sperm move
  3. The percentage of motile sperm
  4. The ability of semen to form a thread Correct answer.

Explanation

Viscosity is assessed by observing the thread formed when semen is gently aspirated with a pipette. A thread longer than 2 cm indicates abnormal viscosity.

Question 12Semen Analysis and Semen Evaluation

Which of the following is the correct method for assessing semen volume?

  1. Using a graduated cylinder or serological pipette Correct answer.
  2. Weighing the sample and assuming density of 1 g/mL
  3. Measuring the height of the sample in the container
  4. Estimating from the collection container markings

Explanation

Semen volume should be measured using a graduated cylinder or a serological pipette for accuracy. Weight-based methods are not recommended because density may vary.

Question 13Semen Analysis and Semen Evaluation

What is the purpose of adding a diluent to a semen sample before counting sperm in a hemocytometer?

  1. To increase the volume for easier counting
  2. To stain the sperm for visibility
  3. To immobilize sperm
  4. To reduce the concentration to a countable range Correct answer.

Explanation

Dilution is used when the sperm concentration is high, to bring it into a range that can be accurately counted in the hemocytometer. The dilution factor is then used in the concentration calculation.

Question 14Semen Analysis and Semen Evaluation

Which of the following is a correct statement about the assessment of sperm vitality?

  1. Vitality is assessed only when motility is very low Correct answer.
  2. Vitality is determined by the percentage of motile sperm
  3. Vitality testing is routinely performed on all samples
  4. Eosin-nigrosin staining is used to identify live sperm

Explanation

Vitality testing is indicated when the proportion of motile sperm is very low (e.g., less than 5%), to distinguish between immotile but alive sperm and dead sperm. Eosin-nigrosin staining is used, where dead sperm take up the dye.

Question 15Semen Analysis and Semen Evaluation

What is the lower reference limit for sperm vitality (live sperm) according to WHO 2010?

  1. 58% Correct answer.
  2. 65%
  3. 75%
  4. 50%

Explanation

The WHO 2010 manual sets the lower reference limit for sperm vitality at 58% live sperm. This is based on the 5th centile of a reference population.

Question 16Semen Analysis and Semen Evaluation

Which of the following is the correct procedure for preparing a semen sample for morphology assessment?

  1. Smear a drop of fresh semen directly onto a slide
  2. Heat-fix the smear before staining
  3. Air-dry and fix the smear before staining Correct answer.
  4. Wash the sperm in saline before smearing

Explanation

For morphology assessment, a thin smear is made, air-dried, and then fixed before staining. Heat fixation is not recommended as it can distort sperm morphology.

Question 17Semen Analysis and Semen Evaluation

A semen sample has a volume of 2.0 mL and a sperm concentration of 10 million/mL. What is the total sperm number?

  1. 30 million
  2. 40 million
  3. 10 million
  4. 20 million Correct answer.

Explanation

Total sperm number = volume × concentration = 2.0 mL × 10 million/mL = 20 million. This is below the WHO lower reference limit of 39 million.

Question 18Semen Analysis and Semen Evaluation

Which of the following is a correct description of the 'round cell' count in semen analysis?

  1. Round cells include leukocytes and immature germ cells Correct answer.
  2. Round cells are counted only in the motility assessment
  3. Round cells are always spermatozoa
  4. Round cells are not clinically relevant

Explanation

Round cells in semen can be leukocytes or immature germ cells. Their concentration is assessed, and if elevated, further testing (e.g., peroxidase staining) is needed to differentiate.

Question 19Semen Analysis and Semen Evaluation

What is the recommended lower reference limit for sperm motility (total motility) in the WHO 2010 manual?

  1. 30%
  2. 50%
  3. 60%
  4. 40% Correct answer.

Explanation

The WHO 2010 manual sets the lower reference limit for total sperm motility (grades a+b+c) at 40%. Progressive motility (grades a+b) has a lower limit of 32%.

Question 20Semen Analysis and Semen Evaluation

During sperm motility assessment, which of the following factors can affect the accuracy of the results?

  1. Temperature of the slide
  2. Time since ejaculation
  3. Thickness of the smear
  4. All of the above Correct answer.

Explanation

Temperature, time since ejaculation, and slide preparation can all influence motility readings. Standardized conditions are essential for reliable results.

Question 21Semen Analysis and Semen Evaluation

Which of the following is the correct definition of 'oligozoospermia'?

  1. Semen volume below 1.4 mL
  2. Sperm concentration below 15 million/mL Correct answer.
  3. Total sperm number below 39 million
  4. Progressive motility below 32%

Explanation

Oligozoospermia is defined as sperm concentration below the WHO lower reference limit of 15 million/mL. Total sperm number below 39 million is also considered oligozoospermia but the term specifically refers to concentration.

Question 22Semen Analysis and Semen Evaluation

A semen sample has a sperm concentration of 5 million/mL and a volume of 4 mL. What is the total sperm number and how does it compare to the WHO lower reference limit?

  1. 10 million; above the limit
  2. 20 million; below the limit Correct answer.
  3. 10 million; below the limit
  4. 20 million; above the limit

Explanation

Total sperm number = 5 million/mL × 4 mL = 20 million. The WHO lower reference limit for total sperm number is 39 million, so 20 million is below the limit.

Question 23Semen Analysis and Semen Evaluation

Which of the following is a correct statement about the assessment of sperm agglutination?

  1. Agglutination refers to sperm sticking to debris
  2. Agglutination is assessed only in fresh samples
  3. Agglutination is always caused by infection
  4. Agglutination is graded as mild, moderate, or severe Correct answer.

Explanation

Sperm agglutination is graded as mild, moderate, or severe based on the extent of clumping. It indicates the presence of antisperm antibodies and should be distinguished from nonspecific aggregation.

Question 24Semen Analysis and Semen Evaluation

What is the recommended method for assessing sperm concentration when the concentration is very low?

  1. Use a hemocytometer with a larger volume
  2. Use a Makler counting chamber Correct answer.
  3. Perform a concentration step by centrifugation
  4. Count in a Neubauer chamber without dilution

Explanation

The Makler counting chamber is designed for lower sperm concentrations and allows direct counting without dilution. It is particularly useful for samples with low concentration.

Question 25Semen Analysis and Semen Evaluation

A semen analysis shows a volume of 1.0 mL, pH 6.8, and absence of fructose. Which condition is most likely?

  1. Congenital bilateral absence of the vas deferens
  2. Hypogonadotropic hypogonadism
  3. Ejaculatory duct obstruction Correct answer.
  4. Varicocele

Explanation

Low volume, acidic pH, and absent fructose suggest ejaculatory duct obstruction, which prevents the addition of seminal vesicle fluid (rich in fructose and alkaline). This leads to a small, acidic ejaculate.

Question 26Semen Analysis and Semen Evaluation

According to the WHO 2010 manual, what is the lower reference limit for semen volume?

  1. 2.0 mL
  2. 2.5 mL
  3. 1.5 mL Correct answer.
  4. 1.0 mL

Explanation

The WHO 2010 manual specifies a lower reference limit of 1.5 mL for semen volume, based on the 5th percentile of men in the reference population. This value is used to identify possible hypospermia.

Question 27Semen Analysis and Semen Evaluation

Which term describes a semen sample with a sperm concentration below the WHO lower reference limit?

  1. Azoospermia
  2. Asthenozoospermia
  3. Oligozoospermia Correct answer.
  4. Teratozoospermia

Explanation

Oligozoospermia is defined as a sperm concentration below the lower reference limit (15 million/mL in WHO 2010). Azoospermia refers to absence of sperm, asthenozoospermia to reduced motility, and teratozoospermia to abnormal morphology.

Question 28Semen Analysis and Semen Evaluation

Which of the following best describes the correct procedure for assessing sperm motility in a fresh semen sample?

  1. Examine a stained smear at room temperature after 4 hours.
  2. Examine a wet preparation at 4°C after 2 hours.
  3. Examine a wet preparation at 37°C within 1 hour of collection. Correct answer.
  4. Examine a fixed sample after centrifugation.

Explanation

Motility should be assessed on a wet preparation maintained at 37°C as soon as possible after liquefaction, ideally within 1 hour of collection, to avoid decline in motility. Staining, cooling, or delay can alter motility results.

Question 29Semen Analysis and Semen Evaluation

A semen sample has a volume of 2.5 mL and a sperm concentration of 40 million/mL. What is the total sperm number per ejaculate?

  1. 160 million
  2. 100 million Correct answer.
  3. 80 million
  4. 40 million

Explanation

Total sperm number is calculated by multiplying semen volume by sperm concentration: 2.5 mL × 40 million/mL = 100 million. This value reflects the total sperm output per ejaculate.

Question 30Semen Analysis and Semen Evaluation

Which of the following is the correct way to report sperm agglutination during semen analysis?

  1. Grade the degree of agglutination (e.g., 0 to 4) and note the type of clumping. Correct answer.
  2. Report agglutination as present or absent without grading.
  3. Report only the percentage of motile sperm that are agglutinated.
  4. Ignore agglutination because it does not affect motility assessment.

Explanation

Agglutination should be graded (for example, on a scale from 0 to 4) and the type (head-to-head, tail-to-tail, etc.) described, as it can interfere with motility and concentration assessments. Simple presence/absence or ignoring it loses clinically relevant information.

Question 31Semen Analysis and Semen Evaluation

Which of the following best defines the term 'viscosity' in semen analysis?

  1. The speed at which sperm move through the seminal fluid.
  2. The resistance of the ejaculate to flow, assessed by observing how it drips from a pipette. Correct answer.
  3. The time required for the sample to liquefy at room temperature.
  4. The concentration of proteins in the seminal plasma.

Explanation

Viscosity refers to the resistance of the semen to flow and is typically assessed by allowing the sample to drip from a pipette or by gently pouring it. It is distinct from liquefaction time and sperm motility.

Question 32Semen Analysis and Semen Evaluation

A semen sample is very viscous and does not liquefy completely. Which of the following is the most appropriate action before performing sperm counting?

  1. Heat the sample to 60°C to reduce viscosity.
  2. Treat with a mucolytic agent or pass through a fine needle, then reassess. Correct answer.
  3. Dilute the sample with water and count immediately.
  4. Discard the sample and request a new collection.

Explanation

High viscosity can interfere with accurate counting; gentle mechanical disruption (e.g., passing through a fine needle) or mucolytic treatment can be used, followed by reassessment. Heating to high temperatures or adding water can damage sperm and alter results.

Question 33Semen Analysis and Semen Evaluation

When assessing sperm concentration using a hemocytometer, which of the following errors would most likely lead to a falsely low count?

  1. Counting too many fields.
  2. Counting immobilized sperm as motile.
  3. Using a dilution factor that is too high.
  4. Not allowing the chamber to settle before counting. Correct answer.

Explanation

If the chamber is not allowed to settle, sperm may not be evenly distributed, often leading to undercounting in some fields and a falsely low concentration. Overcounting fields or misclassifying motility do not directly lower the concentration, and using a high dilution factor would lower the count only if not accounted for.

Question 34Semen Analysis and Semen Evaluation

Which of the following is the correct method for assessing semen volume according to WHO recommendations?

  1. Weigh the collection container before and after collection and convert mass to volume using density. Correct answer.
  2. Measure volume by aspirating the sample into a graduated syringe.
  3. Measure volume by diluting the sample and reading in a hemocytometer.
  4. Estimate volume by visual inspection of the collection container.

Explanation

The WHO recommends determining volume by weighing the collection container before and after collection, then converting mass to volume using the density of semen (approximately 1 g/mL). This is more accurate than visual estimation or other indirect methods.

Question 35Sperm Function and Sperm Preparation Techniques

Which sperm preparation method relies on sperm actively swimming out of a semen layer into a clean culture medium overlay?

  1. Swim-up Correct answer.
  2. Glass wool filtration
  3. Simple wash and centrifugation
  4. Density gradient centrifugation

Explanation

Swim-up separates motile sperm by allowing them to migrate from the semen pellet or layer into an overlaid culture medium, leaving immotile and dead cells behind. It depends on active motility rather than density or adherence.

Question 36Sperm Function and Sperm Preparation Techniques

The primary purpose of adding a cryoprotectant such as glycerol to a sperm freezing medium is to:

  1. Increase sperm motility after thawing
  2. Reduce ice crystal formation during freezing Correct answer.
  3. Neutralize reactive oxygen species
  4. Raise the osmolarity of the extender

Explanation

Cryoprotectants penetrate cells and lower the freezing point, reducing intracellular ice crystal formation that would otherwise damage membranes and organelles. They do not themselves stimulate motility or scavenge reactive oxygen species.

Question 37Sperm Function and Sperm Preparation Techniques

In a discontinuous density gradient preparation, sperm are separated primarily on the basis of:

  1. Cell surface charge
  2. Membrane cholesterol content
  3. Flagellar beat frequency
  4. Buoyant density Correct answer.

Explanation

Density gradient media form layers of differing density, and cells migrate to the layer matching their buoyant density during centrifugation. Mature, morphologically normal sperm tend to have higher density and pellet through the gradient.

Question 38Sperm Function and Sperm Preparation Techniques

Capacitation of sperm in the female reproductive tract is best described as:

  1. Loss of the acrosome before reaching the oocyte
  2. A series of membrane and biochemical changes enabling fertilization Correct answer.
  3. Fusion of the sperm and oocyte membranes
  4. Binding of sperm to the zona pellucida

Explanation

Capacitation involves destabilization of the sperm membrane, changes in cholesterol and ion fluxes, and increased tyrosine phosphorylation, preparing the sperm to undergo the acrosome reaction. It precedes and enables, but is distinct from, zona binding and membrane fusion.

Question 39Sperm Function and Sperm Preparation Techniques

A semen sample is processed by swim-up, and the recovered motile sperm fraction is compared with the original sample. Which change is expected?

  1. Unchanged motility with reduced seminal plasma
  2. Higher percentage of leukocytes
  3. Higher total sperm count with lower motility
  4. Higher motility percentage with lower total count Correct answer.

Explanation

Swim-up enriches for motile sperm, raising the motile percentage, but only a fraction of cells migrate into the overlay, so the absolute number recovered falls. Seminal plasma is also removed, but that alone does not capture the motility enrichment.

Question 40Sperm Function and Sperm Preparation Techniques

The acrosome reaction is characterized by:

  1. Formation of the flagellar midpiece
  2. Release of acrosomal enzymes after fusion of the outer acrosomal and plasma membranes Correct answer.
  3. Condensation of chromatin in the sperm head
  4. Loss of the sperm tail

Explanation

During the acrosome reaction, the outer acrosomal membrane fuses with the overlying plasma membrane, forming vesicles and releasing hydrolytic enzymes that help the sperm penetrate the zona pellucida. Chromatin condensation and midpiece formation occur earlier during spermiogenesis.

Question 41Sperm Function and Sperm Preparation Techniques

Which assay most directly measures the ability of sperm to penetrate cervical mucus?

  1. Zona-free hamster oocyte penetration test
  2. Hypo-osmotic swelling test
  3. Acridine orange staining
  4. Post-coital test Correct answer.

Explanation

The post-coital test examines sperm present in cervical mucus after intercourse and directly assesses sperm-mucus interaction and penetration. The other tests assess membrane integrity or chromatin status rather than mucus penetration.

Question 42Sperm Function and Sperm Preparation Techniques

A laboratory performing density gradient preparation should centrifuge gradients at approximately which speed range to allow efficient sperm migration while preserving viability?

  1. 5000-6000 g for 5 minutes
  2. 100-200 g for 2 minutes
  3. 10,000 g for 1 minute
  4. 300-600 g for 15-30 minutes Correct answer.

Explanation

Density gradient preparations typically use around 300-600 g for 15-30 minutes, which is sufficient to drive sperm through the layers without excessive mechanical damage. Very high speeds or very short spins do not achieve proper separation.

Question 43Sperm Function and Sperm Preparation Techniques

The hypo-osmotic swelling test evaluates which functional property of sperm?

  1. Intact plasma membrane function Correct answer.
  2. Acrosomal enzyme content
  3. DNA fragmentation
  4. Mitochondrial membrane potential

Explanation

In a hypo-osmotic solution, water enters through an intact functional membrane, causing the tail to swell and curl. This reflects membrane integrity and function rather than chromatin or mitochondrial status.

Question 44Sperm Function and Sperm Preparation Techniques

Which factor most strongly determines whether a swim-up or a density gradient is preferred for a sample with high viscosity and debris?

  1. Number of oocytes available
  2. Need to remove debris and non-sperm cells before selecting motile sperm Correct answer.
  3. Desire to minimize handling time regardless of sample quality
  4. Cost of culture medium

Explanation

Density gradients are generally more effective at removing debris, leukocytes, and non-sperm cells before motile sperm are recovered, which is advantageous for viscous or contaminated samples. Swim-up is simpler but less effective at cleaning poor-quality samples.

Question 45Sperm Function and Sperm Preparation Techniques

Sperm mitochondrial membrane potential is most relevant to which aspect of sperm function?

  1. Capacitation-induced cholesterol efflux
  2. Energy supply for motility Correct answer.
  3. Zona pellucida binding specificity
  4. Chromatin packaging

Explanation

Mitochondria in the sperm midpiece generate ATP that powers flagellar motion, so membrane potential reflects the energetic capacity supporting motility. It is not the principal determinant of zona binding, chromatin packaging, or cholesterol efflux.

Question 46Sperm Function and Sperm Preparation Techniques

During density gradient centrifugation, mature morphologically normal sperm typically:

  1. Remain in the upper medium layer
  2. Adhere to the tube wall
  3. Migrate into the pellet at the bottom Correct answer.
  4. Float above the gradient

Explanation

Normal, mature sperm have higher buoyant density and pass through the gradient layers to form a pellet, while debris and less dense abnormal cells remain above. The pellet is then resuspended as the purified fraction.

Question 47Sperm Function and Sperm Preparation Techniques

A sample shows very low motility but adequate concentration. Which preparation approach is most appropriate to recover the maximum number of viable sperm for ART?

  1. Swim-up with a short overlay
  2. No preparation, use neat semen
  3. Simple wash only
  4. Density gradient followed by a brief swim-up Correct answer.

Explanation

When motility is poor, a density gradient recovers viable sperm that would not swim out efficiently, and a brief swim-up can further enrich motile cells without excessive loss. Swim-up alone would yield few cells, and an unprepared sample is unsuitable for most ART procedures.

Question 48Sperm Function and Sperm Preparation Techniques

The zona pellucida binding assay assesses which sperm function?

  1. Ability to fuse with the oolemma
  2. Ability to swim in culture medium
  3. Ability to recognize and bind the oocyte coat Correct answer.
  4. Ability to undergo chromatin decondensation

Explanation

Zona binding assays measure the capacity of sperm to recognize and adhere to the zona pellucida, an early step in fertilization. Fusion and decondensation are later events assessed by different tests.

Question 49Sperm Function and Sperm Preparation Techniques

Which change in culture conditions is most likely to improve sperm survival during a prolonged incubation?

  1. Increasing reactive oxygen species in the medium
  2. Maintaining physiological temperature and pH with appropriate buffering Correct answer.
  3. Removing all protein from the medium
  4. Exposing the sample to direct light

Explanation

Sperm are sensitive to temperature and pH fluctuations, so stable physiological conditions with proper buffering support viability. Added oxidative stress, protein-free medium, and light exposure tend to be detrimental.

Question 50Sperm Function and Sperm Preparation Techniques

A glass wool filtration preparation primarily removes:

  1. Debris and immotile cells Correct answer.
  2. Motile sperm
  3. All leukocytes selectively
  4. Seminal fructose

Explanation

Glass wool fibers trap debris and many immotile or dead cells while allowing motile sperm to pass through, providing a simple cleanup method. It does not selectively remove all leukocytes or seminal fructose.