K251501 · Visby Medical, Inc. · QEP · Oct 1, 2025 · Microbiology
Device Facts
Record ID
K251501
Device Name
Visby Medical Men's Sexual Health Test
Applicant
Visby Medical, Inc.
Product Code
QEP · Microbiology
Decision Date
Oct 1, 2025
Decision
SESE
Submission Type
Dual Track
Regulation
21 CFR 866.3393
Device Class
Class 2
Indications for Use
The Visby Medical Men’s Sexual Health Test is a single-use (disposable), fully integrated, automated Polymerase Chain Reaction (PCR) in vitro diagnostic test intended for the rapid detection and differentiation of DNA from Chlamydia trachomatis and Neisseria gonorrhoeae in male urine specimens. The test results are to aid in the diagnosis of symptomatic or asymptomatic infections with Chlamydia trachomatis and Neisseria gonorrhoeae in males.
Device Story
Single-use, fully integrated, automated PCR diagnostic test for male urine specimens. Input: ~450 μL urine transferred into buffer-filled dropper tube; entire volume (~1.35 mL) added to device sample port. Operation: User slides purple switch to initiate automated lysis, PCR amplification, and detection. Principle: Rehydration of lyophilized reagents; chemical/thermal lysis; thermocycling; hybridization to flow channel probes; enzyme-linked colorimetric assay (HRP/substrate) forming purple precipitate. Output: Visual purple spots in results window for CT, NG, and 'RESULTS VALID' control; green 'READY' light. Used in point-of-care or clinical settings; operated by untrained users. Results available in <30 minutes. Aids clinical diagnosis of CT/NG infections.
Clinical Evidence
Prospective clinical study (n=1272) at 7 US CLIA-waived sites. Compared to 3 FDA-cleared NAATs. CT sensitivity 95.4% (90.8-97.8%), specificity 99.3% (98.6-99.6%). NG sensitivity 100.0% (93.5-100.0%), specificity 99.3% (98.7-99.7%). Invalid rate 0.2% after retest.
Technological Characteristics
Single-use, self-contained, disposable cartridge. Integrated lysis, PCR amplification, and colorimetric detection. No external instrument required. Firmware-based electronic controls monitor power, temperature, and hardware/firmware status. Internal process control (Neisseria subflava) verifies lysis, amplification, and detection. Complies with IEC 62304 for software life cycle.
Indications for Use
Indicated for symptomatic or asymptomatic males aged 14 and older for the detection and differentiation of Chlamydia trachomatis and Neisseria gonorrhoeae DNA in first-catch urine specimens.
Regulatory Classification
Identification
A device to detect nucleic acids from non-viral microorganism(s) causing sexually transmitted infections and associated resistance marker(s) is an in vitro diagnostic device intended for the detection and identification of nucleic acids from non-viral microorganism(s) and their associated resistance markers in clinical specimens collected from patients suspected of sexually transmitted infections. The device is intended to aid in the diagnosis of non-viral sexually transmitted infections in conjunction with other clinical and laboratory data. These devices do not provide confirmation of antibiotic susceptibility since mechanisms of resistance may exist that are not detected by the device.
Special Controls
A device to detect nucleic acids from non-viral microorganism(s) causing sexually transmitted infections and associated resistance marker(s) must comply with the following special controls: (1) The intended use for the 21 CFR 809.10 labeling must include a detailed description of targets the device detects, the results provided to the user, the clinical indications appropriate for test use, and the specific population(s) for which the device is intended. (2) Any sample collection device used must be FDA-cleared, -approved, or -classified as 510(k) exempt (standalone or as part of a test system) for the collection of specimen types claimed by this device: alternatively, the sample collection device must be cleared in a premarket submission as a part of this device. (3) The 21 CFR 809.10(b) labeling must include: (i) A detailed device description, including reagents, instruments, ancillary materials, all control elements, and a detailed explanation of the methodology, including all pre-analytical methods for processing of specimens; (ii) Detailed discussion of the performance characteristics of the device for all claimed specimen types based on analytical studies, including, but not limited to. Limit of Detection, inclusivity, cross-reactivity, interfering substances, competitive inhibition, carryover/cross contamination, specimen stability, with-in lab precision, and reproducibility, as appropriate; (iii) Detailed descriptions of the test procedure, the interpretation of test results for clinical specimens, and acceptance criteria for any quality control testing. (iv) Limiting statements indicating that: (A)a negative test result does not preclude the possibility of infection; (B) the test results should be interpreted in conjunction with other clinical and laboratory data available to the clinician; (C) reliable results are dependent on adequate specimen collection, transport, storage, and processing. Failure to observe procedures in any one of these steps can lead to incorrect results; and (D)if appropriate (e.g., recommended by CDC, by current well-accepted clinical guidelines, or by published peer reviewed research), that the clinical performance is inferior in a specific clinical subpopulation or for a specific claimed specimen type. (v) If the device is intended to detect antimicrobial resistance markers, limiting statements, as appropriate, indicating that: (A)negative results for claimed resistance markers do not indicate susceptibility of detected microorganisms, as resistance markers not measured by the assay or other potential mechanisms of antibiotic resistance may be present; (B) detection of resistance markers cannot be definitively linked to specific microorganisms and the source of a detected resistance marker may be an organism not detected by the assay, including colonizing flora; (C) detection of antibiotic resistance markers may not correlate with phenotypic gene expression; and (D) therapeutic failure or success cannot be determined based on the assay results, since nucleic acid may persist following appropriate antimicrobial therapy. (4) Design verification and validation must include: (i) Detailed device description documentation, including, but not limited to, methodology from obtaining sample to result, design of primer/probe sequences, rationale for target sequence selection, and computational path from collected raw data to reported result (e.g., how collected raw signals are converted into a reported result). (ii) Detailed documentation of analytical studies including but not limited to, Limit of Detection, inclusivity, cross-reactivity, microbial interference, interfering substances, competitive inhibition, carryover/cross contamination, specimen stability, with-in lab precision, and reproducibility, as appropriate. (iii) Detailed documentation and performance results from a clinical study that includes prospective (sequential) samples for each claimed specimen type and, when determined to be appropriate by FDA, additional characterized clinical samples. The study must be performed on a study population consistent with the intended use population and compare the device performance to results obtained from FDA accepted comparator methods. Documentation from the clinical studies must include the clinical study protocol (including a predefined statistical analysis plan) study report, testing results, and results of all statistical analyses. (iv) A detailed description of the impact of any software, including, but not limited to, software applications and hardware-based devices that incorporate software, on the device's functions.
*Classification.* Class II (special controls). The special controls for this device are:(1) The intended use for the labeling required under § 809.10 of this chapter must include a detailed description of targets the device detects, the results provided to the user, the clinical indications appropriate for test use, and the specific population(s) for which the device is intended.
(2) Any sample collection device used must be FDA-cleared, -approved, or -classified as 510(k) exempt (standalone or as part of a test system) for the collection of specimen types claimed by this device; alternatively, the sample collection device must be cleared in a premarket submission as a part of this device.
(3) The labeling required under § 809.10(b) of this chapter must include:
(i) A detailed device description, including reagents, instruments, ancillary materials, all control elements, and a detailed explanation of the methodology, including all pre-analytical methods for processing of specimens;
(ii) Detailed discussion of the performance characteristics of the device for all claimed specimen types based on analytical studies, including Limit of Detection, inclusivity, cross-reactivity, interfering substances, competitive inhibition, carryover/cross contamination, specimen stability, within lab precision, and reproducibility, as appropriate;
(iii) Detailed descriptions of the test procedure, the interpretation of test results for clinical specimens, and acceptance criteria for any quality control testing;
(iv) Limiting statements indicating that:
(A) A negative test result does not preclude the possibility of infection;
(B) The test results should be interpreted in conjunction with other clinical and laboratory data available to the clinician;
(C) Reliable results are dependent on adequate specimen collection, transport, storage, and processing. Failure to observe proper procedures in any one of these steps can lead to incorrect results; and
(D) If appropriate (
*e.g.,* recommended by the Centers for Disease Control and Prevention, by current well-accepted clinical guidelines, or by published peer reviewed research), that the clinical performance is inferior in a specific clinical subpopulation or for a specific claimed specimen type; and(v) If the device is intended to detect antimicrobial resistance markers, limiting statements, as appropriate, indicating that:
(A) Negative results for claimed resistance markers do not indicate susceptibility of detected microorganisms, as resistance markers not measured by the assay or other potential mechanisms of antibiotic resistance may be present;
(B) Detection of resistance markers cannot be definitively linked to specific microorganisms and the source of a detected resistance marker may be an organism not detected by the assay, including colonizing flora;
(C) Detection of antibiotic resistance markers may not correlate with phenotypic gene expression; and
(D) Therapeutic failure or success cannot be determined based on the assay results, since nucleic acid may persist following appropriate antimicrobial therapy.
(4) Design verification and validation must include:
(i) Detailed device description documentation, including methodology from obtaining sample to result, design of primer/probe sequences, rationale for target sequence selection, and computational path from collected raw data to reported result (
*e.g.,* how collected raw signals are converted into a reported result).(ii) Detailed documentation of analytical studies, including, Limit of Detection, inclusivity, cross-reactivity, microbial interference, interfering substances, competitive inhibition, carryover/cross contamination, specimen stability, within lab precision, and reproducibility, as appropriate.
(iii) Detailed documentation and performance results from a clinical study that includes prospective (sequential) samples for each claimed specimen type and, when determined to be appropriate by FDA, additional characterized clinical samples. The study must be performed on a study population consistent with the intended use population and compare the device performance to results obtained from FDA accepted comparator methods. Documentation from the clinical studies must include the clinical study protocol (including a predefined statistical analysis plan) study report, testing results, and results of all statistical analyses.
(iv) A detailed description of the impact of any software, including software applications and hardware-based devices that incorporate software, on the device's functions.
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FDA
U.S. FOOD & DRUG
ADMINISTRATION
# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY
ASSAY AND INSTRUMENT
## I Background Information:
A 510(k) Number
K251501
B Applicant
Visby Medical, Inc.
C Proprietary and Established Names
Visby Medical Men's Sexual Health Test
D Regulatory Information
| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| QEP | Class II | 21 CFR 866.3393 - Device To Detect Nucleic Acids From Non-Viral Microorganism(S) Causing Sexually Transmitted Infections And Associated Resistance Marker(S) | MI - Microbiology |
## II Submission/Device Overview:
A Purpose for Submission:
To obtain market clearance for a new diagnostic device.
B Measurand:
Chlamydia trachomatis DNA
Neisseria gonorrhoeae DNA
C Type of Test:
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
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Qualitative, Polymerase Chain Reaction
## III Intended Use/Indications for Use:
### A Intended Use(s):
See Indications for Use below.
### B Indication(s) for Use:
The Visby Medical Men’s Sexual Health Test is a single-use (disposable), fully integrated, automated Polymerase Chain Reaction (PCR) in vitro diagnostic test intended for the rapid detection and differentiation of DNA from *Chlamydia trachomatis* and *Neisseria gonorrhoeae* in male urine specimens. The test results are to aid in the diagnosis of symptomatic or asymptomatic infections with *Chlamydia trachomatis* and *Neisseria gonorrhoeae* in males.
### C Special Conditions for Use Statement(s):
Rx - For Prescription Use Only
### D Special Instrument Requirements:
Self-contained
## IV Device/System Characteristics:
### A Device Description:
The Visby Medical Men’s Sexual Health Test is a single-use (disposable), fully automated, rapid, compact device that contains PCR assays for qualitative detection of *Chlamydia trachomatis* (CT) and *Neisseria gonorrhoeae* (NG) DNA in male urine samples from symptomatic or asymptomatic individuals. The device automatically performs all steps required to complete lysis, PCR amplification, and detection.
The Visby Medical Men’s Sexual Health Test contains the test cartridge, a fixed volume pipette to transfer the specimen to the dropper tube, and a dropper tube containing sample buffer solution. The test is designed to be simple to use. The patient collects a first catch urine sample in a standard urine collection cup (not provided). The operator starts the test by using a provided fixed-volume disposable transfer pipette to transfer ~450 μL of urine from the collection cup into a dropper tube containing ~900 μL of Visby Medical Men’s Sexual Health Buffer. The operator transfers the entire volume (~1.35 mL) of the sample (urine in buffer) into the sample port of the device by squeezing the dropper tube to release all of the sample into the device sample port. The operator then slides a purple switch on the front of the device to both close the sample port and initiate the fully automated testing process. At this point, blinking white lights on the front of the device indicate the test is in progress. Test results are available in just under 30 minutes at which time a green “READY” status light will appear at the bottom of the device,
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and a purple color will appear in the "RESULTS VALID" spot, indicating a valid test. A purple spot adjacent to "CHLAMYDIA" and/or "GONORRHEA" signifies the presence of amplified CT and/or NG DNA in the sample.
## B Principle of Operation:
When the sample is added to the sample port, it rehydrates a lyophilized internal process control. The sample enters a lysis module, where the DNA in the sample and the internal process control are extracted using a combination of chemical lysis and high temperature. The extracted DNA enters a mixing chamber where it rehydrates lyophilized PCR reagents, followed by thermocycling to amplify target DNA. If present, the amplified pathogen target (CT and/or NG) and internal process control hybridize to specific probes located on a flow channel. Detection of the target-specific PCR product is accomplished via an enzyme-linked colorimetric assay using streptavidin-bound horseradish peroxidase (HRP) and a colorimetric substrate that forms a purple precipitate. Test results can be expected in approximately 30 minutes. A green "Ready" light will appear indicating the test has completed and a purple color will appear in the "Control" spot, indicating a successful internal process control. A purple spot adjacent to "Chlamydia," "Gonorrhoeae," signifies the presence of amplified CT or NG DNA in the sample. In the rare case of a hardware failure, the power light, progress light bar or the green "Ready" light will be off or flashing indicating an error has occurred and the test result window will indicate an invalid test. In the case of an invalid test, the operator is instructed to run a new test.
## C Instrument Description Information:
1. Instrument Name:
Visby Medical Men's Sexual Health Test - the instrument is integrated into the reaction cartridge.
2. Specimen Identification:
Manual
3. Specimen Sampling and Handling:
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The specimen is self-collected by the patient and placed in the Visby collection media. Thus, a liquid sample is available for transfer onto the device. All further sample processing takes place within the device.
4. Calibration:
No calibration is required.
5. Quality Control:
Each Visby Medical Men’s Sexual Health Test includes both built-in electronic controls and an internal process control. These controls are designed to ensure that the device is operating within specification.
The electronic control uses firmware to monitor the device during the run and illuminates a green circle LED next to “READY” at the completion of a run. The firmware also generates errors when, (1) the device experiences a power interruption, (2) the device is operated outside of its operating temperature range, or (3) a hardware or firmware failure is detected. Electronic controls are communicated to the operator via status lights on the bottom of the device. If an error occurs, the status lights will communicate the error to the operator.
The internal process control is comprised of a PCR assay to a control organism (Neisseria subflava) that is contained in the device. The process control is designed to ensure that all steps in the testing process including lysis, amplification of target sequences, and amplicon detection are working properly. A purple spot adjacent to “RESULTS VALID” in the results window indicates a successful internal process control. If a purple spot is not present in the “RESULTS VALID” window, then the test result is invalid.
External controls:
Positive and negative external controls manufactured by ZeptoMetrix Corporation, Buffalo, NY. The labeling states that the external controls must be tested with each new lot or shipment received and once for each untrained operator.
V Substantial Equivalence Information:
A Predicate Device Name(s):
Visby Medical Sexual Health Test
B Predicate 510(k) Number(s):
K220407
C Comparison with Predicate(s):
| Device & Predicate Device(s): | K251501 | K220407 |
| --- | --- | --- |
| Device Trade Name | Visby Medical Men’s | Visby Medical Sexual |
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| | Sexual Health Test | Health Test |
| --- | --- | --- |
| **General Device Characteristic Similarities** | | |
| Intended Use/Indications For Use | The Visby Medical Men’s Sexual Health Test is a single-use (disposable), fully integrated, automated Polymerase Chain Reaction (PCR) in vitro diagnostic test intended for the rapid detection and differentiation of DNA from *Chlamydia trachomatis* and *Neisseria gonorrhoeae* in male urine specimens. The test results are to aid in the diagnosis of symptomatic or asymptomatic infections with *Chlamydia trachomatis* and *Neisseria gonorrhoeae* in males. | The Visby Medical Sexual Health Test is a single-use (disposable), fully integrated, automated Polymerase Chain Reaction (PCR) in vitro diagnostic test intended for use in point-of-care or clinical laboratory settings for the rapid detection and differentiation of DNA from *Chlamydia trachomatis*, *Neisseria gonorrhoeae*, and *Trichomonas vaginalis* in self-collected female vaginal swab specimens using the Visby Medical Sexual Health Vaginal Specimen Collection Kit in a health care setting. The test results are to aid in the diagnosis of symptomatic or asymptomatic infections with *Chlamydia trachomatis*, *Neisseria gonorrhoeae*, and *Trichomonas vaginalis*. |
| | | |
| **General Device Characteristic Differences** | | |
| Specimen Type | Patient-collected male Urine | Patient-collected vaginal swab |
| Collection kit | Urine cup (not provided) | Swab collection kit |
| Organisms Detected | *Chlamydia trachomatis* (CT)
*Neisseria gonorrhoeae* (NG) | *Chlamydia trachomatis* (CT)
*Neisseria gonorrhoeae* (NG)
*Trichomonas vaginalis* |
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(TV)
VI Standards/Guidance Documents Referenced:
1. IEC 62304 Edition 1.1 2015-06 Consolidated Version 13-79 Medical device software – Software life cycle processes.
2. Class II Special Controls as per 21 CFR 866.3393.
VII Performance Characteristics (if/when applicable):
A Analytical Performance:
1. Precision/Reproducibility:
A reproducibility study of the Visby Medical Men’s Sexual Health Test was conducted by untrained operators from three external sites representative of CLIA waived settings. Six untrained operators (two untrained operators per site) performed the study using panels of blind coded specimens containing low (1X LOD) or moderate (4X LOD) positive CT or NG, or negative samples. Samples were prepared in pooled negative clinical matrix (male urine). Operators tested multiple samples of each panel member over six days. The percent positive results for the CT moderate and CT low positive samples were 100% (108/108) and 98.1% (106/108), respectively. The percent positive results for the NG moderate and NG low positive samples were 100% (108/108) and 100% (108/108), respectively. The Reproducibility Study site-to-site qualitative results (percent positive results) are presented in the table below.
Table 1. Reproducibility
| Panel Member | Site 1 | Site 2 | Site 3 | Overall Agreement | |
| --- | --- | --- | --- | --- | --- |
| | % Agreement^{1} (count) | % Agreement (count) | % Agreement (count) | % Agreement (count) | 95% Confidence Interval |
| Moderate Positive CT | 100% (36/36) | 100% (36/36) | 100% (36/36) | 100% (108/108) | 96.6-100% |
| Low Positive | 97.2% (35/36) | 97.2% (35/36) | 100% (36/36) | 98.1% (106/108) | 93.5-99.5% |
| Moderate Positive NG | 100% (36/36) | 100% (36/36) | 100% (36/36) | 100% (108/108) | 96.6-100% |
| Low Positive | 100% (36/36)^{2} | 100% (36/36) | 100% (36/36) | 100% (108/108) | 96.6-100% |
| Negative | 100% (36/36) | 100% (36/36) | 100% (36/36) | 100% (108/108) | 96.6-100% |
1 Agreement = agreement with expected results
2 One test was unexpectedly positive for CT
2. Linearity:
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Not applicable.
3. Analytical Specificity/Interference:
Cross-reactivity
The Visby Medical Men’s Sexual Health Test analytical specificity was evaluated in a study testing samples containing organisms that are closely related to the target organisms or that are present as normal flora in urine specimens. Eight-three different organisms were included in the study (3 of which were tested in silico), with each organism tested in three replicates. There was one false positive CT results (out of 3 replicates) with inactivated HIV-1 (ZeptoMetrix NATHIV1-LIN). Additional HIV-1 organism testing with ten replicates in the absence of the inactivation fluid did not replicate the cross-reactivity. A warning was added to labeling indicating the possibility of HIV-1 cross-reactivity with the device. No other cross reactivity was observed with the organisms at the concentrations tested. The following organisms were tested for possible cross-reactivity:
- Acinetobacter lwoffii
- Actinomyces israelii
- Atopobium vaginae
- Bacteroides fragilis
- Bacteroides ureolyticus
- Bifidobacterium adolescentis
- Bifidobacterium longum
- Candida albicans*
- Candida glabrata
- Candida parapsilosis
- Candida tropicalis
- Chlamydophila pneumoniae*
- Clostridium difficile
- Chlamydophila psittaci*
- Clostridium perfringens
- Corynebacterium genitalium
- Corynebacterium xerosis
- Cryptococcus neoformans
- Cutibacterium acnes
- Enterobacter cloacae
- Enterococcus faecalis*
- Escherichia coli*
- Fusobacterium nucleatum
- Haemophilus ducreyi
- Kingella dentrificans
- Klebsiella aerogenes
- Klebsiella oxytoca
- Lactobacillus acidophilus
- Lactobacillus brevis
- Lactobacillus jensenii
- Lactococcus lactis
- Lactobacillus vaginalis
- Listeria monocytogenes
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Mobiluncus curtisii
Mobiluncus mulieris
Mycoplasma genitalium*
Mycoplasma hominis
Neisseria cinerea
Neisseria elongata (3 strains)
Neisseria flava
Neisseria flavescens (2 strains)
Neisseria lactamica (4 strains)
Neisseria meningitidis serogroup a*
Neisseria meningitidis serogroup b
Neisseria meningitidis serogroup c
Neisseria meningitidis serogroup d
Neisseria meningitidis serogroup w-135
Neisseria meningitidis serogroup y
Neisseria mucosa (3 strains)
Neisseria perflava
Neisseria polysaccharea
Neisseria sicca (3 strains)
Neisseria subflava
Pentatrichomonis hominis
Peptostreptococcus anaerobius
Prevotella bivia
Proteus mirabilis
Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus agalactiae
Streptococcus pyogenes
Trichomonas tenax*
Ureaplasma urealyticum
Herpes simplex virus I*
Herpes simplex virus II
Human papilloma virus 16 E6/E7 (Transformed cells)
HIV-1 (inactivated)*
HIV-1 (culture fluid)
Gardnerella vaginalis
Klebsiella pneumoniae
Pseudomonas aeruginosa
Ureaplasma parvum
Trichomonas vaginalis*
## Microbial Interference
The performance of the Visby Medical Men’s Sexual Health Test was evaluated for its ability to accurately detect CT and NG in the presence of other clinically relevant pathogens. This study tested a total of 11 organisms (denoted by * in the list above) spiked into positive samples containing 3x LOD concentrations of CT and NG in pooled urine in three replicates. The organisms were chosen based on the likelihood of their presence in a urine sample or genetic similarities to the target organisms. No microbial interference was observed with any of the organisms tested.
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# Competitive Interference
A competitive interference study was performed to evaluate the performance of the Visby Medical Men's Sexual Health Test when CT and NG are present in samples at varying concentrations and combinations to simulate mixed infection conditions (presence of multiple target organisms). Each of the target organisms (CT and NG) were spiked into pooled urine at varying concentrations and tested in triplicate. Low concentrations were prepared at 3x LOD for the respective organisms, and high concentrations were prepared at 1 x $10^{6}$ units/mL. An additional double-positive sample was tested at 1x LOD for both organisms (Sample #10). A total of 10 mixed infection combinations were tested. All 10 mixed infection combinations returned 3/3 valid devices with the expected results, demonstrating that the presence of high concentration of one organism ( $1 \times 10^{6}$ units/mL) does not interfere with the detection of low levels (3x LOD) of an alternate organism or cause false positive results for an organism that is not present in the sample.
Table 2: Competitive Interference
| Organisms and Concentration | | CT (# Positive / # Tested) | NG (# Positive / # Tested) |
| --- | --- | --- | --- |
| CT | NG | | |
| Low | High | 3/3 | 3/3 |
| Low | Low | 3/3 | 3/3 |
| Low | Negative | 3/3 | 0/3 |
| High | High | 3/3 | 3/3 |
| High | Low | 3/3 | 3/3 |
| High | Negative | 3/3 | 0/3 |
| Negative | High | 0/3 | 3/3 |
| Negative | Low | 0/3 | 3/3 |
| Negative | Negative | 0/3 | 0/3 |
| 1x LOD | 1x LOD | 3/3 | 3/3 |
# Interfering Substances
The performance of the Visby Men's Sexual Health Test was evaluated with potentially interfering substances that may be present in clinical urine specimens. A total of 30 potentially interfering substances were individually spiked into urine samples and tested in the absence or presence of CT and NG at a concentration of $3\mathrm{x}$ LOD. Positive and negative samples were tested in triplicate. All 30 substances tested provided the expected results (both positive and negative tests) when tested at the specified concentration. The table below shows the interferents and concentrations used in this study.
Table 3: Interfering Substances
| Interfering Substance | Concentration Tested |
| --- | --- |
| Acidic Urine | pH 4 |
| Alkaline Urine | pH 9 |
| Albumin (BSA) | 500 μg/mL |
| Beta Estradiol | 0.07 mg/mL |
| Bilirubin | 100 μg/mL |
| Glucose | 1 mg/mL |
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| Leukocytes | 1x10^{6} cells/mL |
| --- | --- |
| Mucin (Bovine) | 0.80% w/v |
| Progesterone | 0.07 mg/mL |
| Seminal Fluid | 5% v/v |
| Whole Blood | 1% v/v |
| Acetaminophen | 2200 μg/mL |
| Amoxicillin Trihydrate | 6900 μg/mL |
| Aspirin | 1200 μg/mL |
| Azithromycin | 2900 μg/mL |
| Biotin | 10 μg/mL |
| Ceftriaxone | 1200 μg/mL L |
| Doxycycline | 500 μg/mL |
| Erythromycin | 900 μg/mL |
| Ibuprofen | 1200 μg/mL |
| Metronidazole | 1500 μg/mL |
| Naproxen | 1200 μg/mL |
| Phenazopyridine Hydrochloride | 500 μg/mL |
| Tetracycline Hydrochloride | 1700 μg/mL |
| Trimethoprim | 250 μg/mL |
| Sulfamethoxazole | 1800 μg/mL |
| Abreva Cold Sore Cream | 0.25% w/v |
| KY Jelly Lubricant | 0.25% w/v |
| Preparation H Hemorrhoidal Ointment | 0.25% w/v |
| Talcum Powder | 0.25% w/v |
4. Assay Reportable Range:
Not applicable.
5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):
Specimen Stability
A specimen stability study was performed to determine how long a urine specimen can be stored in various conditions before being tested with the Visby Medical Men’s Sexual Health Test. Low positive (2x LOD) and negative samples of CT and NG were created in clinical urine matrix and stored at room temperature (15-30 °C) or at refrigerated temperature (2-8 °C). Ten samples were tested at baseline and ten or twenty samples tested at various timepoints throughout the study duration. The study results demonstrated that the specimen can be stored up to 28 hours at 2-8 °C (refrigerated temperature) or up to 3 hours at 15-30 °C (room temperature).
6. Detection Limit:
Limit of Detection
The Limit of Detection (LOD) for the Visby Medical Men’s Sexual Health Test was determined for CT in elementary bodies per mL (EB/mL) and NG in colony forming units per mL (CFU/mL), from two distinct serovars or strains, spiked into negative urine. dilutions. The LOD values for each strain were estimated by probit analysis of the results from a range-finding study of five different concentrations (2-fold dilution series) in replicates of ten per concentration. LOD is defined as the lowest concentration per sample that can be detected 95% of the time during confirmation testing for each of the strains. The probit-calculated
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LODs were confirmed by testing 20 replicates demonstrating that at least 19 out of 20 replicates were positive empirically. The LOD of the Visby Medical Men's Sexual Health Test for each organism are summarized in the Tables below.
Table 4: Limit of detection for CT Serovar D
| CT Serovar D | Concentration (EB/mL) | Detection Rate (# Positive / # Tested) |
| --- | --- | --- |
| LOD | 32.5 | 20/20 |
| | 10.8 | 13/20 |
Table 5: Limit of detection for CT Serovar H
| CT Serovar H | Concentration (EB/mL) | Detection Rate (# Positive / # Tested) |
| --- | --- | --- |
| LOD | 14.0 | 20/20 |
| | 4.7 | 17/20 |
Table 6: Limit of detection for NG strain ATCC 49226
| NG (ATCC 49226) | Concentration (CFU/mL) | Detection Rate (# Positive / # Tested) |
| --- | --- | --- |
| LOD | 2.5 | 20/20 |
| | 0.8 | 16/20^{1} |
1 Two samples returned an initial invalid result; the samples were positive upon retest
Table 7: Limit of detection for NG strain ATCC 19424
| NG (ATCC 19424) | Concentration (CFU/mL) | Detection Rate (# Positive / # Tested) |
| --- | --- | --- |
| LOD Confirmation | 32.0 | 19/20^{1} |
1 One sample returned an initial invalid result; the sample was positive upon retest
## Inclusivity
The analytical reactivity of the Visby Medical Men's Sexual Health Test was evaluated by testing dilutions of quantified stocks of CT and NG strains prepared by spiking into pooled negative clinical urine matrix at concentrations at 3x LOD. A total of 14 CT serovars and 30 NG strains were tested in three replicates. Samples that were not detected in all three replicates at the initially contrived concentrations were retested at a higher concentration. For C. trachomatis, 13 of the 14 serovars were detected at 3x LOD (97.5 EB/mL). One serovar (CT LGV II VR-902B) had a detectable minimum concentration of 6x LOD (195.0 EB/mL). For N. gonorrhoeae, 30 of the 30 strains were detected at 3x LOD (96.0 CFU/mL). Tables 2 and 3 show the strains that were positive in all three replicates at the concentrations shown.
Table 8: Inclusivity for C. trachomatis
| Organism | Serovar |
| --- | --- |
| C. trachomatis | Serovar F |
| | Serovar Ba |
| | Serovar E |
| | Serovar A |
| | Serovar B |
| | Serovar G |
| | Serovar I |
| | Serovar J |
| | Serovar K |
| | Serovar LGV I |
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| Serovar LGV II |
| --- |
| Serovar LGV III |
| Serovar C |
| Serovar E, Swedish variant (nvCT) |
Table 9: Inclusivity for N. gonorrhoeae
| Organism | Strain (ATCC designation) | |
| --- | --- | --- |
| N. gonorrhoeae | BAA-1833 | 27632 |
| | BAA-1839 | 27633 |
| | BAA-1847 | 31148 |
| | 9826 | 31149 |
| | 9827 | 31151 |
| | 9830 | 31356 |
| | 10874 | 31397 |
| | 11688 | 31398 |
| | 11689 | 31401 |
| | 19088 | 31402 |
| | 23050 | 31403 |
| | 23051 | 31406 |
| | 27628 | 35541 |
| | 27629 | 43069 |
| | 27631 | 49981 |
7. Assay Cut-Off:
Not applicable.
8. Accuracy (Instrument):
Not applicable.
9. Carry-Over:
Not applicable.
B Comparison Studies:
1. Method Comparison with Predicate Device:
See Clinical Study section below.
2. Matrix Comparison:
Not applicable.
C Clinical Studies:
Clinical Performance
Clinical performance for the Visby Medical Men’s Sexual Health Test was established through a prospective study enrolling individuals at seven geographically diverse clinical sites. The study
K251501 - Page 12 of 14
{12}
was designed to enroll sexually active users aged 14 and above. A total of 16 untrained operators, representative of CLIA waived users, participated in the study. Participants were provided a collection cup and instructions to collect a first-catch urine specimen. An operator, untrained in the use of the subject device, immediately collected the specimen cup and performed the Visby Medical Men's Sexual Health Test according to the quick reference guide. The remaining specimen was aliquoted and sent to two reference laboratories for comparator testing. The samples were first tested by reference labs using two FDA-cleared nucleic acid amplification tests (NAATs). If the two test results were discordant, a third FDA-cleared NAAT was used as a tie-breaker. The study consisted of 1289 prospectively subjects enrolled from October 2024 through March 2025. Seventeen (17) study specimens were excluded from the performance evaluation due to procedural errors by site study staff or incomplete study procedures $(n = 8)$ , withdrawal of consent $(n = 4)$ , lack of a valid Visby test result $(n = 3)$ , or for the subject not meeting inclusion criteria $(n = 2)$ , leaving 1272 Visby Men's Sexual Health Test results with paired valid comparator results. There were 55 initial invalids out of 1276 evaluable specimens obtained during the clinical study. After retesting, the final invalid rate was $3/1276 = 0.2\%$ . The clinical performance for the Visby Medical Men's Sexual Health Test is shown below:
Table 10: Clinical performance for CT by Symptom Status
| Symptom Status | N | TP | FP | TN | FN | Sensitivity (95% CI) | Specificity (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Symptomatic | 310 | 57 | 2 | 249 | 2 | 96.6% (88.5-99.1%) | 99.2% (97.1-99.8%) |
| Asymptomatic | 962 | 88 | 6 | 863 | 5 | 94.6% (88.0-97.7%) | 99.3% (98.5-99.7%) |
| Overall | 1272 | 145 | 8 | 1112 | 7 | 95.4% (90.8-97.8%) | 99.3% (98.6-99.6%) |
TP=true positive; FP=false positive; TN=true negative; FN=false negative
Table 11: Clinical performance for NG by Symptom Status
| Symptom Status | N | TP | FP | TN | FN | Sensitivity (95% CI) | Specificity (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| Symptomatic | 310 | 48 | 1 | 261 | 0 | 100.0% (92.6-100.0%) | 99.6% (97.9-99.9%) |
| Asymptomatic | 962 | 7 | 7 | 948 | 0 | 100.0% (64.6-100.0%) | 99.3% (98.5-99.6%) |
| Overall | 1272 | 55 | 8 | 1209 | 0 | 100.0% (93.5-100.0%) | 99.3% (98.7-99.7%) |
TP=true positive; FP=false positive; TN=true negative; FN=false negative
D Clinical Cut-Off:
Not applicable.
E Expected Values/Reference Range:
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During the clinical evaluation, the following positivity rate for detection of CT and NG in males was observed for the Visby Medical Men’s Sexual Health Test:
Table 13: Expected Values
| | CT Positive | NG Positive | CT + NG Positive |
| --- | --- | --- | --- |
| Total | 139/1272 (10.9%) | 49/1272 (3.9%) | 14/1272 (1.1%) |
F Other Supportive Instrument Performance Characteristics Data:
Not applicable
VIII Proposed Labeling:
The labeling supports the finding of substantial equivalence for this device.
IX Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
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Learn the FDA Browser
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.
