Created at 12:32 a.m. May, 05, 2026
Author:
enirenberg
Type of change:
Updated content
Rationale for change
The quad screen is part of prenatal testing; it is erroneous to call it neonatal as that would have to be post-partum.
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*Different from trisomy 18 (Edwards) and trisomy 13 (Patau)


| Trisomy | Patau (13) | Edward (18) | Down (21) |
|---|---|---|---|
| First Trimester | |||
| β-hCG | ↓ | ↓ | ↑ |
| PAPP-A | ↓ | ↓ | ↓ |
| Second Trimester | |||
| β-hCG | ↔ | ↓ | ↑ |
| Inhibin A | ↔ | ↔ or ↓ | ↑ |
| α-fetoprotein (AFP) | ↔ | ↓ | ↓ |
| Estriol | ↔ | ↓ | ↓ |


Lecture Notes
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Missed Questions
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Pathoma
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Boards and Beyond
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First Aid


Sketchy





Watch Down Syndrome





Watch Down Syndrome
Sketchy Extra
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Picmonic
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Pixorize


Review Down Syndrome (Trisomy 21)


Review Down Syndrome (Trisomy 21)
Physeo
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OME
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