Detection of Common Sexually Transmitted Infections: Swabs vs Urine

Detection of Common Sexually Transmitted Infections: Swabs vs Urine

Common STIs

According to the Centers for Disease Control and Prevention, an estimated 20% of people in the U.S. had at least one Sexually Transmitted Infection (STI) in the year they studied (2018). 

Almost half of people who get an STI will contract their first one between the ages of 15 to 24. Some STIs are curable in early stages and can cause irreversible harm if left untreated. For this reason, early detection of common STIs is vital to personal and public health.

This guide explores the most common STIs, how they’re detected, as well as, symptoms and prevention.


Gonorrhea is a widespread bacterial infection in the genitals, throat or rectum. You can contract it through oral, vaginal, or anal sex. Additionally, you can pass it to the baby if you have it while pregnant. Most gonorrhea is curable with antibiotics. Failure to treat it can lead to infertility and chronic pelvic pain.

You may have no symptoms, primarily if you were assigned male at birth. But can still pass it on to others.

Symptoms of gonorrhea in include:

  • Pain or burning when peeing
  • Vaginal discharge
  • Vaginal bleeding between periods
  • White, green, or yellow discharge from the penis
  • Swollen testicles
  • Itching, bleeding, discharge, and pain in the rectum when you go

Gonorrhea can be detected by urine test or swab of the vagina, cervix, anus, and or throat. Urine testing will not detect the bacteria in other parts of the body. So, it’s crucial to answer sexual history questions honestly to get the proper test.


Chlamydia is also a bacterial infection that can be passed by oral, anal, or vaginal sex. It is curable with antibiotics. But left untreated, it can cause infertility and long-term pelvic pain. You can also pass it to a baby during delivery.

You may have no symptoms, primarily if you were assigned male at birth. But you can still pass it on to others and you and your partner can pass bacterial infections back and forth if only one is treated.

Symptoms of chlamydia can include:

  • Pain or burning when peeing
  • Vaginal discharge
  • Vaginal bleeding between periods
  • White, green, or yellow discharge from the penis
  • Swollen testicles
  • Itching, bleeding, discharge, and pain in the rectum when you go
  • Abdominal pain

We can detect chlamydia through a urine test. Depending on the location, a swab test may be needed.


A blood-borne virus causes HIV. It is not curable. But with treatment, it can become undetectable. This can significantly reduce your risk of transmitting it to others. Because HIV is transmitted through blood and body fluids, having another STD increases your risk of getting HIV when exposed as well as sharing it with partners.

HIV goes through 3 distinct stages.

During stage 1, you have flu-like symptoms which may or may not include mouth sores. You are very contagious during this stage

Stage 2 can last a decade or more and you may have no symptoms. But you can still transmit it to others. 

Stage 3 is AIDS. During this stage your immune system is compromised. You struggle to fight even minor infections. You may also:

  • Lose weight quickly
  • Have night sweats
  • Have prolonged diarrhea 
  • Develop sores
  • Experience pneumonia (fluid on the lungs)
  • Get purplish, pink, or red blotches on/under skin, mouth, nose, eyelids
  • Have memory loss and other thinking and processing problems

We detect HIV with one of two blood tests.

The Rapid HIV test detects proteins your body produces to fight the virus. It can give you results quickly. But it may not detect HIV soon after exposure. You need retesting to be sure.

Molecular or RNA HIV testing can identify the actual RNA molecules of the virus. But it takes several days to get the results back.


Genital herpes can be caused by herpes simplex virus type 1 or 2. Type 1 is often called oral herpes because it’s more common on the lips, which causes cold sore blisters. This kind is often contracted during childhood from friends or family through close contact (drinking after people, putting toys in your mouth, friendly kisses).

Type 2 is often referred to as genital herpes. But both oral and genital herpes are more likely to be passed through sexual activity. Saliva, genital fluids, and sores can all carry both types, depending on what a person was exposed to. 

Herpes is not curable. However, medication can reduce and shorten outbreaks. This can lower—but not eliminate—your chance of passing it to someone else.

Symptoms include painful open blisters on the mouth, genitals, or anal area that can take a week or more to heal. However, like many STIs, you may have no symptoms for months or years, making testing critical.

Herpes is detected by swabbing the mouth, rectum, or genital areas, particularly open sores.

Mycoplasma Genitalium (Mgen)

This curable bacterial infection can happen inside the cervix, penis, or anus. If left untreated, it can cause infertility and lifelong pain. You can transmit it through vaginal or anal sex.

Pain when peeing and an odd discharge are common symptoms.

We can use urine tests to detect most mycoplasma. A swab is needed if the bacteria may be on the cervix or anus.


This is a curable parasitic infection. It’s often unnoticeable without testing in most people. But it can cause infertility and premature births if left untreated. The parasites can live in the vagina and the urethra (that you urinate out of). They can cause pain during sex and urination. You may also have a yellow or greenish discharge.

We generally detect trichomoniasis through urine testing.

Bacterial Vaginosis

This describes irritation in the vagina caused by an overabundance of certain bacteria. It is characterized by imbalances in the “good” and “bad” bacteria that live naturally in the vagina. Unhealthy habits like douching or otherwise trying to clean the inside of the vagina can lead to this imbalance. 

This is not necessarily a sexually transmitted disease, but having multiple sexual partners can increase your risk. And it’s important to mention sex because having vaginosis can increase your risk of catching STDs.

It’s curable with antibiotics.

Symptoms include:

  • Fishy odor
  • Gray vaginal discharge
  • Burning when peeing
  • Itching on the labia around the vagina

We detect bacterial vaginosis through urine test.  Your provider may also collect some vaginal fluid using a swab. This fluid can then be tested for various bacteria to determine which type is causing the irritation.

Preventing STDs

You can reduce your risk of contracting STDs by:

  • Limiting the number of sexual partners
  • Finding a monogamous partner and both of you staying committed to each other
  • Vaccination for STDs that have one. Currently, those are HPV and hepatitis B.
  • Making sure you use a condom correctly during oral, anal, and vaginal sex
  • Getting tested for common STDs at least once a year or if you have symptoms. Some people need testing more often.
  • Encouraging your partner to get tested and treated so you don’t get reinfected after treatment.

You can order STD testing online without an upfront provider visit and get results in 1-3 days. Learn more.