Certain types of human papillomavirus (HPV) infection can lead to cervical cancer - in fact, this virus is the main cause of most of these cancers - which implies that the HPV test is essential for detecting this condition. However, not all women attend screening appointments due to fear of pain, concerns about privacy and stigma, or lack of awareness, among other reasons.
Now, screening can overcome these obstacles thanks to the research of a team from the Zhongnan Hospital of Wuhan University in China, which has studied the ability of a new menstrual blood test to detect HPV in more than 3,000 women, with data collected by The BMJ.
Although the evidence is limited, "the menstrual blood test for detecting HPV infection appears to be a useful and non-invasive alternative to screening," notes Zheng Hu, from the Department of Gynecologic Oncology at the mentioned center and the main author of the new study, who emphasizes that the new test "would allow women to collect samples at home, thus offering a practical way to expand access to screening."
To address this gap, researchers compared the diagnostic accuracy of menstrual blood with cervical samples collected by doctors to detect high-grade cervical lesions (CIN2+ / CIN3+), which generally require treatment.
Their findings were based on the study of 3,068 women aged between 20 and 54 with regular menstrual cycles, enrolled between September 2021 and January 2025 in four urban and three rural communities in the Hubei province, China.
Each participant provided three samples for analysis: a menstrual blood sample collected with a minipad (a sterile cotton strip attached to the absorbent area of a standard sanitary pad, called the index test); a cervical sample collected by a doctor or comparison test, and finally, an additional cervical sample collected by a doctor for processing in the laboratory.
Participants also had access to a WeChat mobile application (Early Test) to access test results and healthcare provider advice.
As indicated in the study, the main outcome measure was the diagnostic sensitivity and specificity of the tests. Sensitivity indicates how effectively a test detects people with a disease, while specificity indicates how effectively a test detects people without it.
Menstrual blood samples collected with a minipad for the HPV test showed a sensitivity of 94.7% for detecting CIN2+, which was comparable to samples collected by doctors (92.1%).
Although minipad samples showed lower specificity than doctor-collected samples (89.1% versus 90.0%), the negative predictive value (probability that a person with a negative test result truly does not have the disease) was identical (99.9%) for both collection methods.
There was also no significant difference in terms of the positive predictive value (probability that a person with a positive test result truly has the disease) between both collection methods (9.9% versus 10.4%), and the referral for additional tests, such as cervical colposcopy, was comparable (10.1 versus 9.6 referrals per detected CIN2+).
Furthermore, another improvement point is that "integration with the Early Test mobile application further streamlined result reporting and communication with patients, enhancing the feasibility of implementing large-scale screening," the authors note.
Zheng Hu explains, however, that these are observational findings, so "firm conclusions cannot be drawn about cause and effect." Additionally, several study limitations are acknowledged, warranting "careful consideration."
The authors suggest that data from this large-scale community study "demonstrate the utility of using menstrual blood collected with minipads for HPV testing as a standardized and non-invasive alternative or replacement for cervical cancer detection."
"The work is very pioneering, although it is in the research phase. At the moment, "its clinical applications are not clear," says Xavier Bosch, emeritus researcher at the Catalan Institute of Oncology (ICO), principal investigator at the Bellvitge Biomedical Research Institute (IDIBELL), and professor at the Open University of Catalonia (UOC).
In his opinion, as he tells SMC, the main points of interest in the study focus, first, on the fact that menstrual blood, like any cervicovaginal fluid and urine, can carry cells from the genital/urinary tract, including viral markers (DNA; RNA). Therefore, "detection has some value. The importance of the study lies in knowing if this value is equal to the performance of the DNA test in already validated samples (cytology, urine, or self-sample) or if it identifies some cases that escape conventional sampling."
It also needs to be demonstrated that "blood does not interfere with the measurement of viral markers, a problem that was significant with the early PCR tests." Thus, his initial impression is that "this is an area where we already have good tests, and menstrual blood collection may add more confusion than benefit."
For Pluvio Coronado, associate professor of Obstetrics and Gynecology at the Complutense University of Madrid, head of the Section at the San Carlos Clinical Hospital in Madrid, and president of the Spanish Association for the Study of Menopause, the idea seems innovative, but "I don't see it succeeding."
Unclear clinical applications and limitations
He justifies his opinion, first, because "it requires menstrual blood, and not all women will have it because screening is up to age 65; second, because many women with hormonal IUDs (Mirena and similar) do not have periods, and long-acting contraceptives are increasingly popular. Third, it does not work in pregnant women. On the other hand, now there is a trend towards self-sampling, which is less invasive and has a similar result to professional sampling," he tells SMC.
He explains that this strategy "was already attempted with urine collection, but it failed, and the same will happen with menstrual blood. It could be an alternative for women who do not want to manipulate their genitals for religious or other reasons and do not wish to go to the doctor. However, I do not see it as a method for population screening."
Even acknowledging that, overall, it is an interesting work because it proposes a non-invasive alternative to conventional HPV detection (performed by a doctor or midwife) and could be especially useful for women who do not attend screening, Marta del Pino, from the Gynecologic Oncology Unit at the Clinic Hospital of Barcelona, scientific coordinator at the Clinical Institute of Gynecology, Obstetrics, and Neonatology (ICGON), and associate professor at the University of Barcelona, points out that it cannot be understood "as an immediate replacement for current screening."
In her opinion, there are significant limitations: "it includes only women who menstruate and have regular cycles, and it uses a prototype device that is not commercially available. Additionally, as in many screening studies, not all women with negative results underwent biopsy; this can introduce verification bias and overestimate the test's performance," she explains to SMC.
Therefore, "the value of this research is to open an additional alternative that could be beneficial in certain scenarios, but it still needs replication and implementation research."