A Bartholin cyst is a fluid-filled sac that forms when the Bartholin glands, located on either side of the vaginal opening, become blocked. These glands produce lubrication for the vagina, and when their ducts are obstructed, fluid accumulates, leading to the formation of a cyst. Most Bartholin cysts are painless and may not require treatment. However, if the cyst becomes infected, it can cause pain, swelling, and discomfort. In such cases, medical intervention may be necessary, which can include drainage or surgical removal of the cyst.