PAPP-A MoM Calculator
Actual biomarker multiple-of-median with independently matched gestational age, assay, units and maternal-factor convention. No marker identity or screening probability inferred. Independently measured compatible definitions/units required; ratio is not a diagnosis, efficacy measure or safety/clinical threshold.
Description
PAPP-A multiples of the median express an observed value relative to an applicable matched median.
PAPP-A multiples of the median express an observed value relative to an applicable matched median.1
Clinical adjustment of the measurement or median is independent of this division.
When to use PAPP-A MoM Calculator
Use this tool to calculate or review the supplied observations under the stated rules. Establish the observation date, units, measurement context and independently applicable clinical reference or calibrated model.
How to use PAPP-A MoM Calculator and understand its results
- Establish the observation date, units, measurement context and independently applicable clinical reference or calibrated model.
- Enter observedPappAValue, callerVerifiedMatchedGestationalMedian, using the field meanings and rules below, then run the tool.
- Read result.observedRatio. Use the units and sign conventions below.
- Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| observedPappAValue | Observed papp a value | number | Required |
| callerVerifiedMatchedGestationalMedian | Caller verified matched gestational median | number | Required |
Supply a nonnegative observedPappAValue and strictly positive callerVerifiedMatchedGestationalMedian. Divide the first by the second for a dimensionless ratio. The general ratio calculation does not clamp the result or require the numerator to be no greater than the denominator; a larger numerator can return above one. Establish matching observation scope and units independently.
observedRatio=1×observedPappAValue/callerVerifiedMatchedGestationalMedian Use the matching field units and the exact boundary, ordering and reference rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Structured result; its nested fields below contain the actual calculation or selected reference | object |
| result.observedRatio | Observed Ratio; dimensionless ratio, without percent scaling | number |
{
"input": {
"observedPappAValue": 2,
"callerVerifiedMatchedGestationalMedian": 4
},
"output": {
"result": {
"observedRatio": 0.5
}
}
}Limitations and assumptions
Dating evidence, acquisition conditions and applicable clinical references remain independently established. The output describes supplied observations or a conditional model without diagnosing an outcome, choosing a dose or verifying clinical applicability.
Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.
Alternative or Complementary methods
For a related step, use Quad Screen Risk Calculator: Quad screening combines independently adjusted marker information with a calibrated probability model. For a complementary comparison, use Combined Screening Risk Calculator: Combined screening uses adjusted marker coordinates with a calibrated probability model.
References
-
PAPP-A MoM Calculator — tool.io
Similar or alternative tools
- Quad Screen Risk Calculator
Quad screening combines independently adjusted marker information with a calibrated probability model.
- Combined Screening Risk Calculator
Combined screening uses adjusted marker coordinates with a calibrated probability model.