Oligospermia
Oligospermia: mild oligospermia, 10 ≤ sperm concentration < 20 × 106/ml; moderate oligospermia, 5 ≤ sperm concentration < 10 × 106/ml; severe oligospermia, 1 ≤ sperm concentration < 5 × 106/ml and extreme oligospermia < 1 × 106/ml (WHO 4th edition).
Weak spermatozoa
Weak spermatozoa: mild weak spermatozoa, 20% ≤ PR < 32%; moderate weak spermatozoa, 10% ≤ PR < 20%; severe weak spermatozoa, 1 ≤ PR ≥ < 10% and extreme weak spermatozoa, PR < 1% (WHO 5th edition)
Weak spermatozoa: sperm motility (a+b) below the lower limit of the reference value. Mild weak spermatozoa, 30% ≤ sperm motility < 50%; moderate weak spermatozoa, 10% ≤ sperm motility < 30%; severe weak spermatozoa, 1% ≤ sperm motility < 10% and extreme weak spermatozoa, sperm motility < 1% (WHO 4th edition).