The Bartholin glands are a pair of pea-sized, vulvovaginal, mucous-secreting vestibular glands that are located in the labia minora in the 4- and 8-o'clock positions, beneath the bulbospongiosus muscle. A Bartholin cyst is a fluid-filled sac that develops in one of the Bartholin glands or ducts when the duct that drains the fluid from the gland becomes blocked and causes the duct and gland to swell. A Bartholin gland abscess develops either when a Bartholin cyst becomes infected or when the Bartholin gland itself becomes infected.