| UE | uncertain etiology; under elbow; uninvolved epidermis; upper esophagus; upper extremity |
|---|---|
| UO | under observation; undetermined origin; urethral orifice; urinary output |
| u/o | under observation |
| BBB | 1) Bundle Branch Block 2) Blood Brain Barrier - Blood Brain Barrier |
| BBBB | Bilateral Bundle Branch Block |