| RIO | right inferior oblique |
|---|---|
| ROIH | right oblique inguinal hernia |
| RPO | right posterior oblique |
| RSO | radiation safety officer; Resident Surgical Officer; right superior oblique [muscle] |
| SO | salpingo-oophorectomy; Schlatter-Osgood [test]; second opinion; sex offender; spheno-occipital [sync... |