<qa>  What must be a negative serum or urine pregnancy test?- WOCBP must have a negative serum or urine pregnancy test minimum sensitivity 25 IUL or equivalent units of HCG. The first should be performed within 10 to 14 days and the second within 24 hours prior to the start of the study drug. A prescription for lenalidomide for a female of childbearing potential must not be issued by the prescriber until negative pregnancy tests have been verified by the prescriber. 