The presence of visible genital warts and a simultaneous negative test result for the human papillomavirus (HPV) can seem contradictory. HPV is a common sexually transmitted infection that causes nearly all cases of genital warts, making a negative test result counterintuitive when symptoms are present. This apparent conflict reflects the specific purpose and limitations of standard HPV screening methodologies. Understanding the distinction between the virus types and the focus of the available tests provides the necessary clarity.
The Underlying Cause of Genital Warts
Genital warts are a physical manifestation of infection by specific strains of the human papillomavirus (HPV). HPV is a large group of over 200 related viruses, with about 40 types capable of infecting the genital area. These genital types are divided into low-risk and high-risk categories.
The vast majority of genital warts are caused by low-risk HPV types, specifically types 6 and 11, which account for approximately 90% of all cases. They cause benign growths but are rarely associated with cancer development.
High-risk types, such as HPV 16 and 18, cause most HPV-related cancers, including cervical, anal, and throat cancers. The physical appearance of a wart signals a low-risk HPV infection, which is distinctly different from the high-risk infection targeted by standard screening.
How Standard HPV Screening Is Conducted
Standard HPV testing is primarily a tool for cancer prevention, not a general screen for all HPV types. Its main application is in cervical cancer screening for women, often performed alongside or as a primary screen to the Pap test. This screening detects high-risk HPV types that can lead to precancerous changes on the cervix.
Clinical guidelines recommend HPV testing for women generally aged 30 to 65. These tests specifically look for the DNA of the 14 most cancer-causing HPV types, including HPV 16 and 18. The methodology detects the genetic material of these high-risk strains.
There is no widely standardized, routine HPV screening test for men or a general blood test for HPV in either sex. Since existing tests focus on high-risk types in cervical samples, this targeted approach is intentionally blind to the low-risk types that cause most visible warts.
Why Visible Warts Can Exist Alongside Negative Test Results
The most common reason for a negative HPV test despite the presence of genital warts is the difference between the virus causing the symptom and the virus the test is designed to detect. Warts are caused by low-risk types, particularly HPV 6 and 11, which are not included in the panels of high-risk HPV tests used for cancer screening. If a person has only these low-risk strains, the standard test will correctly return a negative result for the high-risk, cancer-associated types.
The standard screening test is performed on a cervical sample in women to assess cancer risk in that specific area. A negative cervical HPV test only confirms the absence of high-risk HPV DNA on the cervix at the time of the test. It does not assess the presence of low-risk HPV types on the external genitalia, where the warts are visible.
For men, the lack of a standardized screening test means a positive molecular result is not expected. The diagnosis of genital warts is made visually. Therefore, a man with visible warts would not have a positive HPV test because the test designed to detect his low-risk infection is not routinely performed.
Clinical Diagnosis and Next Steps
When genital warts are present, the diagnosis is typically made visually by a healthcare provider. This clinical diagnosis is often sufficient to confirm the condition, as the warts themselves are evidence of an active HPV infection. A molecular test is generally not needed to establish the diagnosis.
If the visual diagnosis is uncertain, a small tissue sample may be removed and examined in a lab (biopsy). This confirms the characteristic cellular changes caused by HPV infection, a method separate from the standard high-risk HPV DNA test.
Once confirmed, the next steps focus on managing the growths. Treatment options range from topical medications applied at home to in-clinic procedures like cryotherapy or surgical excision. Women should continue routine cervical cancer screening with Pap tests and high-risk HPV co-testing, addressing the separate risk posed by high-risk HPV types.