The Anatomy of the Urethra

The urethra is a thin tube that connects to the bladder in order to empty urine out of the body. The female urethra is short, about 1.5 inches long, while the male urethra is longer at 7 to 8 inches in length as it runs length of the penis. The male urethra not only carries urine out of the bladder, but it also transports semen.

Anatomy

The male urethra is divided into three parts: the prostatic urethra, membranous urethra, and the spongy urethra. The prostatic urethra starts at the neck of the bladder and is located in the prostate. This is typically the widest part of the urethra, which then connects to the membranous urethra, found in the urogenital diaphragm. The membranous urethra is also surrounded by the sphincter muscle, which is what holds urine in until you’re able to get to a restroom. Last, the spongy urethra makes up the bottom portion of the urethra with many subdivisions such as the bulbous and penile urethra. This is the longest section of the urethra and runs from urogenital diaphragm to the tip of the penis, where urine and semen are then expelled.

Each section of the male urethra has its own supply of arteries to help with blood flow. The prostatic urethra uses the inferior vesical artery (found in the pelvis near the lower bladder), the membranous urethra uses the bulbourethral artery (located in the bulb of the penis), and the spongy urethra uses the pudendal artery, found deep in the pelvis.

The female urethra is a bit more straightforward, as it has less distance to cover. It starts at the bladder and runs through the pelvic floor. It opens onto the perineum after passing through the sphincter muscle. There are three layers of the female urethra, muscular, erectile, and mucous. Within the mucous layer are the Skene’s glands, which can produce a watery substance during sexual arousal. Similar to the male urethra, blood flow stems from the internal pudendal artery.

Anatomical Variations

There are a few congenital (present at birth) conditions that may cause the urethra to not work properly, leading to infection and other issues. These include the urethra not being in the right place (clinically referred to as hypospadias). This is seen in males when the opening urethra does not come out of the tip of the penis. Hypospadias is corrected surgically under general anesthesia, typically when the child is still young or even an infant.

Other variations are when the urethra is shorter than it should be (which can happen in both males and females), a urethral stricture (a narrowing of the urethra), a blockage, duplication of urethras, or a prolapsed urethra—a bulging out at the opening. All of these variations can impact the flow of urine, which leads to increased risk of urinary tract infections (UTI) over time as well as possible damage to the kidneys. For example, in one study, Greek researchers noted a direct correlation of post-sex UTIs and shorter urethras in those with female anatomy.

Function

The urethra’s main responsibility is to let urine pass from the bladder out of the body. This is done when the brain tells the bladder when it’s time to squeeze and the sphincter muscle to relax, releasing urine through the urethra. This same mechanism is used in males when they ejaculate and sperm is carried through the urethra. The main difference between urination and ejaculation is that instead of the brain, bladder, and sphincter muscle communicating, men have nerves in the spinal cord, vas deferens, seminal vesicles, and prostate that work together to close the opening of the bladder and move semen down the penis and through the urethra.

Associated Conditions

Due to anatomical variations of the urethra, genetics, or external factors, such as suffering an injury, there are a few main urethra disorders:

• Urethra cancer
• Urethral strictures: A narrowing of the urethra tube
• Urethritis: Inflammation of the urethra caused by infection
• Urethral diverticulum: A pocket that forms in the urethra and can fill with urine, leading to pain or difficulty urinating.

Urethritis, the most general, all-encompassing condition, is different than a UTI. Urethritis happens when bacteria like gonorrhea or chlamydia cause swelling and pain in the urethra. UTIs cause infection in the urinary tract as a whole, which can be caused by a urethra defect among other issues in the urinary tract.

In general, there can be many causes behind urethral pain, including bacteria, skin conditions, and even certain medications or food. There are also gender-specific causes, such as benign prostate hyperplasia in men and epididymitis. Women can suffer urethral pain due to products like spermicides, soaps, lotions, and douches, in addition to intercourse, yeast infections, and bacterial vaginosis. Even menopause can lead to a prolapsed urethra in severe cases.

It's important to discuss any pain or discomfort in your urethra or urinary tract with your healthcare provider. They will be able to assess your overall health, age, and lifestyle factors, in addition to running one or more of the below diagnostic tests to pinpoint what exactly is causing your pain, and if it's affecting your urethra directly or indirectly.

Tests

There are a few tests that can be done in order to diagnose a urethra disorder. They include:

• Cystoscopy: A thin tube (cystoscope) with a camera is inserted through the urinary opening, up the urethra, and into the bladder, with a live video feed.
• Urethral discharge culture: A cotton swab is inserted into the tip of the urethra to determine if there is an infection. This test is only performed on those who have a penis.
• Urinalysis: Biochemical and microscopic examination of the urine can detect infections and inflammation.
• Urethral ultrasound: Imaging of the abdominal area in order to diagnose any issues in the urethra.
• Retrograde urethrogram: Used most widely in male patients who may have suffered trauma of the urethra, this test is an X-ray of the bladder and urethra. It's done with a contrast agent in order to see any blockages or strictures in the urethra.

Sometimes it can be difficult to tell what area of the urinary tract your pain is coming from, particularly in those with female anatomy since the urethra is so short. Your healthcare provider will be able to tell which tests are right for you based on your symptoms, such as any difficulty or issues passing urine in addition to pain or discomfort when urinating or ejaculating.