| PIS | preinfarction syndrome; primary immunodeficiency syndrome; Provisional International Standard |
|---|---|
| POSSUM | Pictures of Standard Syndromes and Undiagnosed Malformations |
| PPD-S | purified protein derivative-standard |
| QAS | quality assurance standard |
| RSA | rabbit serum albumin; regular spiking activity; relative specific activity; relative standard accura... |