Physical Examination of Semen for Investigation of Infertility

Examination is conducted subsequent to the liquefaction of semen, typically occurring within 20-30 minutes of ejaculation.

Visual Appearance

Normal semen exhibits a viscous and opaque gray-white appearance. Following extended periods of abstinence, it may display a slight yellow tint.

Viscosity

Immediately after ejaculation, normal semen is characterized by thickness and viscosity. Liquefaction, facilitated by proteolytic enzymes secreted by the prostate, occurs within 30 minutes. Failure of liquefaction within 60 minutes is considered abnormal. The sample's viscosity is evaluated by filling a pipette with semen and observing its flow back into the container. In normal semen, it drips drop by drop. If droplets form ‘threads’ longer than 2 cm, viscosity is heightened. Increased semen viscosity adversely impacts sperm motility, leading to poor invasion of cervical mucus. This condition often results from infections of the seminal vesicles or prostate.

Volume

The volume of ejaculated semen should typically exceed 2 ml and is measured post-liquefaction. A volume less than 2.0 ml is abnormal and is associated with a low sperm count.

pH

A drop of liquefied semen is applied to pH paper with a range of 6.4-8.0, and the pH is recorded after 30 seconds. Normal pH ranges from 7.2 to 8.0 one hour post-ejaculation. The portion of semen contributed by seminal vesicles is basic, while the portion from the prostate is acidic. A low pH (< 7.0) in conjunction with the absence of sperm (azoospermia) suggests an obstruction of ejaculatory ducts or the absence of the vas deferens. Low pH is typically linked to low semen volume, as most of the volume is supplied by seminal vesicles.