Infertility is defined as the inability to conceive a pregnancy after one year of regularly trying. When certain sexually transmitted diseases (STDs) are left without treatment, they can cause long-term damage to the reproductive organs, significantly increasing the risk of this outcome. The possibility of fertility impairment depends on the specific infection and the duration of time the disease is allowed to progress unnoticed within the body. Awareness of which infections pose the greatest risk and understanding the way they cause harm is important for protecting future reproductive health.
STDs Most Likely to Cause Infertility
The infections that are the most significant contributors to preventable infertility globally are the bacterial infections, Chlamydia and Gonorrhea. These two common STDs are particularly dangerous because they frequently present without any noticeable symptoms, especially in women. This asymptomatic nature allows the bacteria to ascend silently into the upper reproductive tract, where they inflict damage over time.
In women, up to 10% to 15% of those with untreated Chlamydia will develop Pelvic Inflammatory Disease (PID), and a similar risk exists for Gonorrhea. These two bacteria are responsible for the majority of PID cases, which is the direct cause of tubal-factor infertility.
In contrast, other STIs like Human Papillomavirus (HPV) or Herpes Simplex Virus (HSV) do not typically cause direct physical damage to the fallopian tubes or sperm ducts. While advanced Syphilis can indirectly lead to complications that affect fertility, it is not considered a primary direct cause in the same manner as Chlamydia and Gonorrhea.
Biological Pathways to Reproductive Damage
Untreated bacterial infections cause damage primarily through severe inflammation that leads to the formation of scar tissue and blockages.
Female Reproductive System
In the female reproductive system, the infection typically begins in the cervix before ascending through the uterus into the fallopian tubes, causing Pelvic Inflammatory Disease (PID). This ascending infection triggers an immune response that damages the delicate ciliated lining of the fallopian tubes.
The resulting inflammation causes the formation of scar tissue and adhesions, which can partially or completely block the tubes. This blockage prevents the egg and sperm from meeting for fertilization, leading to infertility.
Scarring also impairs the movement of the cilia, which are hair-like structures responsible for sweeping a fertilized egg toward the uterus. If a fertilized egg gets stuck in a damaged tube, it results in an ectopic pregnancy, which is a life-threatening complication.
Male Reproductive System
In the male reproductive system, the bacteria can travel from the urethra to the epididymis, the coiled tube behind the testicle that stores and carries sperm, causing inflammation known as epididymitis. This inflammation can lead to the formation of scar tissue within the epididymis or the vas deferens, the tube that transports sperm. The scarring causes a blockage that physically prevents sperm from being released during ejaculation, potentially resulting in obstructive azoospermia or oligospermia. Up to 40% of patients with epididymitis may experience permanent low sperm count or no sperm in their semen, even after the bacterial infection is cured.
Testing and Treatment: Preventing Long-Term Harm
The long-term harm to reproductive health caused by these infections is largely preventable through timely diagnosis and treatment. Since Chlamydia and Gonorrhea are often asymptomatic, particularly in their early stages, regular screening is the most effective way to prevent permanent damage. The Centers for Disease Control and Prevention (CDC) recommends annual screening for all sexually active women younger than 25, as well as for older women with risk factors like a new or multiple partners.
When detected, bacterial STDs are highly treatable with a course of antibiotics. This treatment effectively eradicates the bacteria and halts the progression of the inflammatory process, preventing further scarring. However, it is important to understand that once significant scar tissue or blockages have formed in the fallopian tubes or epididymis, the damage is often irreversible. Early intervention is therefore paramount, as treatment can prevent infertility but cannot always undo the anatomical damage that has already occurred.