The prostate gland is a small, muscular organ located in the male reproductive system, positioned just below the bladder and in front of the rectum. Its primary role involves producing a fluid that contributes to semen, nourishing sperm and lubricating the urethra. Understanding the typical shape of this gland is helpful because deviations can indicate various health considerations.
The Typical Prostate Shape
A healthy adult prostate resembles a walnut or a chestnut. It weighs approximately 15-25 grams and has a volume of about 20-25 cubic centimeters (cc). The dimensions are around 4 cm wide, 3 cm high, and 2 cm thick.
It surrounds the urethra, the tube that carries urine and semen out of the body. Its normal, elastic consistency and smooth surface, often described as having a groove dividing it into two symmetrical halves, allow for the unimpeded flow of urine and seminal fluid.
Age-Related Changes in Prostate Shape
As men age, the prostate gland commonly undergoes changes in its shape and size, a phenomenon often associated with benign prostatic hyperplasia (BPH). BPH is a non-cancerous enlargement of the prostate, affecting about 50% of men between ages 51 and 60, increasing to around 80% in men over 70. This growth typically begins around age 25 and continues throughout most of a man’s life.
The prostate’s shape can become larger and more spherical as it enlarges, growing from the size of a walnut to that of an apricot by age 40, and a lemon or even a tennis ball by age 60. This enlargement often occurs in the transition zone of the prostate, which directly surrounds the urethra. As the prostate grows inward, it can compress the urethra, leading to common urinary symptoms such as increased frequency, urgency, a weak or slow urine stream, or the sensation of incomplete bladder emptying.
Detecting and Understanding Prostate Shape Changes
Doctors assess prostate shape changes through various diagnostic methods. A common initial step is the digital rectal exam (DRE), where a healthcare professional inserts a gloved, lubricated finger into the rectum to feel the prostate’s size, shape, and texture. This allows for the detection of any bumps, hard areas, or asymmetry, suggesting changes from its normal smooth, elastic consistency.
Imaging techniques like transrectal ultrasound (TRUS) provide more detailed visual information about the prostate’s shape and volume. This procedure involves inserting a small probe into the rectum, which uses sound waves to create images of the gland, revealing its size, any irregularities, or the presence of nodules. While DRE can sometimes underestimate prostate size, especially for larger glands, ultrasound offers a precise measurement of prostate volume. Urinary symptoms often prompt these evaluations, as they are a direct consequence of the prostate’s changing shape pressing on the urethra.