No, a woman may not immerse with the patch on. The patch, along with any remaining adhesive, should be removed for immersion.
Doctors disagree as to whether a woman can replace the same patch after removing it for mikveh. Some doctors feel that a patch is still effective as long as it sticks unaided. Others insist that a new patch should be used, though this slightly increases the cost of using this method (using four patches per month instead of three). Please consult your physician with any questions about this issue.
Another contraceptive option with a similar mechanism of action, NuvaRing, is left in place in the vagina for three weeks, and can be removed and returned at the mikveh. This may be a viable option for women who would be using a new patch after immersion but for whom the additional cost would be difficult.
Please let us know if we can be of further assistance.