| Obs | observation, observed; obstetrics, obstetrician |
|---|---|
| Obst | obstetrics, obstetrician |
| OG | obstetrics and gynecology; occlusogingival; oligodendrocyte; optic ganglion; orange green; orogastri... |
| O&G | obstetrics and gynecology |
| SGO | Surgeon General's Office; surgery, gynecology, and obstetrics |