<qa>  What is a negative serum or urine pregnancy test?- Women who are using oral contraceptives, other hormonal contraceptives vaginal products, skin patches, or implanted or injectable products, or mechanical products such as an intrauterine device or barrier methods diaphragm, condoms, spermicides to prevent pregnancy, or are practicing abstinence or where their partner is sterile eg, vasectomy should be considered to be of childbearing potential. WOCBP must have a negative serum or urine pregnancy test minimum sensitivity 25 IUL or equivalent units of HCG within 72 hours before the start of ipilimumab. 