Tampon. Tampons are placed into the vagina to absorb the blood and cells discharged during a menstrual period. A tampon is in its sterile packaging at left. At centre is a tampon in the guide-tube used to insert it into the vagina. At right is a tampon as it would appear in the vagina after being released from the guide-tube. A menstrual period regularly occurs because the lining (endometrium) of the uterus breaks down if the woman has not been impregnated during the previous month.