The Sysmex® XT-Series Hematology Analyzer is a quantitative, automated hematology analyzer and leukocyte differential counter for in vitro diagnostic use in clinical laboratories. The XT- Series Body Fluid Application adds a quantitative, automated procedure for analyzing body fluids such as cerebrospinal fluid, serous fluid and synovial fluid to the XT- Series, providing enumeration of the WBCs and the RBCs.
Device Story
The XT-Series Body Fluid Application is an automated software/reagent update for the Sysmex XT-Series Hematology Analyzer; it enables quantitative analysis of body fluids (CSF, serous, synovial). The device uses fluorescent flow cytometry (lateral scatter/fluorescence) for WBC counts and Direct Current (DC) detection for RBC counts. It is operated by laboratory personnel in clinical settings. The system processes samples to provide automated cell counts, which are displayed to the clinician. These outputs assist in the clinical assessment of body fluid samples, replacing or supplementing manual counting methods. The application provides standardized, reproducible cell enumeration, reducing the subjectivity and labor associated with manual microscopy.
Clinical Evidence
Clinical performance was established by comparing the XT-Series Body Fluid Application to the predicate XE-2100 Series Body Fluid Application. Studies demonstrated excellent correlation between the two methods, confirming equivalent performance for the enumeration of WBCs and RBCs in body fluids.
Technological Characteristics
Automated hematology analyzer utilizing flow cytometry principles. Sensing involves side scatter, forward scatter, and fluorescent intensity of nucleated cells. Reagents include Cellpack, Sulfolyser, Stromatolyser-FB, Stromatolyser-4DL, Stromatolyser-4DS, and Ret-Search II. The system is designed for clinical laboratory use.
Indications for Use
Indicated for use in clinical laboratories for quantitative, automated analysis of body fluids (cerebrospinal, serous, and synovial) to provide enumeration of white blood cells (WBCs) and red blood cells (RBCs).
Regulatory Classification
Identification
An automated differential cell counter is a device used to identify one or more of the formed elements of the blood. The device may also have the capability to flag, count, or classify immature or abnormal hematopoietic cells of the blood, bone marrow, or other body fluids. These devices may combine an electronic particle counting method, optical method, or a flow cytometric method utilizing monoclonal CD (cluster designation) markers. The device includes accessory CD markers.
Special Controls
*Classification.* Class II (special controls). The special control for this device is the FDA document entitled “Class II Special Controls Guidance Document: Premarket Notifications for Automated Differential Cell Counters for Immature or Abnormal Blood Cells; Final Guidance for Industry and FDA.”
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE
A. 510(k) Number:
K061150
B. Purpose for Submission:
Added indication on the Sysmex® XT Series Automated Hematology Analyzer
C. Measurand:
White Blood Cell Count (WBC) and Red Blood Cell Count
D. Type of Test:
The XT-Series Body Fluid Application adds a quantitative, automated procedure for analyzing body fluids such as cerebrospinal fluid, serous fluid, and synovial fluid to the XT-Series, providing enumeration of the WBCs and RBCs.
E. Applicant:
Sysmex America, Inc.
F. Proprietary and Established Names:
Body Fluid Application for the XT-Series Automated Hematology Analyzer
G. Regulatory Information:
1. Regulation section:
21 CFR 864.5220, Automated differential cell counter
2. Classification:
Class II
3. Product code:
GKZ
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4. Panel:
Hematology (81)
H. Intended Use:
1. Intended use(s):
The Sysmex XT-Series Hematology Analyzer is a quantitative, automated hematology analyzer and leukocyte differential counter for in vitro diagnostic use in clinical laboratories.
2. Indication(s) for use:
The XT-Series Body Fluid Application adds a quantitative, automated procedure for analyzing body fluids such as cerebrospinal fluid, serous fluid and synovial fluid to the XT-Series, providing enumeration of the WBCs and the RBCs.
3. Special conditions for use statement(s):
These matrices have been validated on the XT-Series: Cerebrospinal fluid, serous fluid (peritoneal, pleural, ascites, dialysate, pericardial, paracentesis, abdominal thoracentesis, trach aspiration, and bronchial fluid) and synovial fluid.
4. Special instrument requirements:
Sysmex Automated Hematology Analyzer, XT-Series.
I. Device Description:
The XT-Series Body Fluid Application adds a quantitative, automated procedure for analyzing body fluids such as cerebrospinal fluid, serous fluid and synovial fluid to the XT-Series, providing enumeration of the WBCs and the RBCs.
J. Substantial Equivalence Information:
1. Predicate device name(s):
Sysmex XE-2100 Series Body Fluid Application
2. Predicate 510(k) number(s):
K040073
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3. Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended Use | To provide a quantitative determination of blood cells in body fluids such as cerebrospinal fluid, serous fluid, and synovial fluid. | Same |
| Methodology | Cell count is performed on an automated hematology analyzer. | Same |
| Specimen Type | Body fluids such as cerebrospinal fluid, serous fluid, and synovial fluid. | same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Reagents | Cellpack, Sulfolyser
Stromatolyser-FB
Stromatolyser-4DL
Stromatolyser-4DS
Stromatolyser-NR
Stromatolyser-IM
Cellsheath
Ret-Search II | Cellpack Sulfolyser
Stromatolyser-FB
Stromatolyser-4DL
Stromatolyser-4DS |
| Accuracy | Comparison to the XE-2100 Series Body Fluid Application demonstrated excellent correlation. | Performance was established in a previous 510(k) using a manual method. |
K. Standard/Guidance Document Referenced (if applicable):
Premarket Notifications for Automated Differential Cell Counters for Immature or Abnormal Cells; Final Guidance for Industry and FDA, December 4, 2001
L. Test Principle:
Fluorescent flow cytometry using lateral scattered light and lateral fluorescent light are used to determine the White Blood Cell count. The Direct Current (DC) detection method is used for the Red Blood Cell count.
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M. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
1. Within-run precision was determined by using samples that were run in the open mode ten times consecutively. Conclusion: The average CV% results for WBC samples ≥0.05 x 10³/μL and for RBC samples ≥0.01 x 10⁶/μL were acceptable.
2. Between-day precision using e-Check was monitored for the time period of the evaluation. Results were within acceptable ranges for e-Check as stated in the manufacturer’s specifications.
b. Linearity/assay reportable range:
WBC and RBC linearity were evaluated by diluting body fluid samples with instrument diluent to obtain results at low levels of detection. R squared values for WBCs ranged from 0.9974 to 1.0. R squared values for RBCs ranged from 0.9655 to 0.9990. Conclusion: The WBC and RBC parameters were linear at low levels for body fluid specimens.
c. Traceability, Stability, Expected values (controls, calibrators, or methods):
N/A
d. Detection limit:
N/A
e. Analytical specificity:
N/A
f. Assay cut-off:
N/A
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# 2. Comparison studies:
a. Method comparison with predicate device:
Table 1: Accuracy of XT vs. XE White Blood Cell Counts
| Fluid Type | N= | R | Slope | Intercept |
| --- | --- | --- | --- | --- |
| CSF | 47 | 1.00 | 1.0348 | -0.0022 |
| Serous* | 150 | 1.00 | 0.9705 | 0.0625 |
| Synovial | 33 | 1.00 | 0.9703 | 0.1571 |
| Body Fluids combined | 228 | 1.00 | 0.9709 | 0.0644 |
| Body Fluids ≥0.05x103/μL | 193 | 1.00 | 0.9706 | 0.0766 |
*Serous fluid included peritoneal, pleural, ascites, dialysate, pericardial, paracentesis, abdominal, thoracentesis, trach aspiration, and bronchial fluid samples.
Table 2 : Accuracy of XT vs XE Red Blood Cell Counts
| Fluid Type | N= | R | Slope | Intercept |
| --- | --- | --- | --- | --- |
| Body Fluids combined | 209 | 1.00 | 1.0224 | -0.0028 |
| Body Fluids ≥0.01x106/μL | 89 | 1.00 | 1.0205 | -0.0069 |
Table 3 : Accuracy of XT vs XE and Manual WBC and RBC Counts
| Fluid Type | N= | R | Slope | Intercept |
| --- | --- | --- | --- | --- |
| WBC Body Fluids Combined | 97 | 1.00 | 0.9454 | 0.229 |
| WBC ≥0.05x103/μL Body Fluids combined | 65 | 1.00 | 0.9441 | 0.2972 |
| RBC Body fluids | 71 | 1.00 | 0.6632 | 0.007 |
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b. Matrix comparison: All three body fluid types (CSF, Serous, Synovial) provide strong positive correlations when comparison is made between the manual counts with the automated counts.
# 3. Clinical studies:
a. Clinical Sensitivity:
N/A
b. Clinical specificity:
N/A
c. Other clinical supportive data (when a. and b. are not applicable):
Carryover: Carryover data was collected by analyzing a high sample three consecutive times then analyzing a low sample three times. Conclusion: Carryover was $\geq 1\%$ as stated in the manufacturer specification.
Table 4: WBC and RBC Carryover (%)
| % Carryover | WBC | RBC | Manufacturer Specification |
| --- | --- | --- | --- |
| CSF | 0.08 | 0.00 | ≥1% |
| | 0.00 | 0.00 | ≥1% |
| | 0.14 | 0.00 | ≥1% |
| | 0.00 | 0.00 | ≥1% |
| Serous Fluid | 0.12 | 0.00 | ≥1% |
| | 0.08 | 0.00 | ≥1% |
| | 0.16 | 0.00 | ≥1% |
| Synovial Fluid | 0.32 | 0.00 | ≥1% |
| | 0.12 | 0.00 | ≥1% |
| | 0.10 | 0.00 | ≥1% |
| | 0.27 | 0.00 | ≥1% |
| | -0.21 | 0.00 | ≥1% |
# 4. Clinical cut-off:
N/A
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5. Expected values/Reference range:
Due to the unavailability of obtaining normal body fluid samples, it is difficult for laboratories to establish expected values: therefore all laboratories will reference textbook values as their expected values as was the case with these study sites.
Table 5: Adult Expected Values for Body Fluids
| Body Fluid Type | WBC | RBC |
| --- | --- | --- |
| CSF | <5 mononuclear cells/μL | NA |
| Peritoneal fluid | <500/mL | NA |
| Pleural fluid | NA (WBCs have limited value) | NA |
| Synovial fluid | <200/μL | NA |
SOURCE: Kjelksberg C. and Knight J. Body Fluids: Laboratory Examination of Cerebral, Seminal, Serous, & Synovial Fluids. 3rd ed. Chicago, IL: ASCP Press, 1993.
N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.
O. 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.