A follicular cyst is a fluid-filled sac that forms on an ovary. It is a type of functional ovarian cyst, which means it develops as a normal part of the menstrual cycle. These cysts are common for those in their reproductive years and are almost always non-cancerous.
Formation During the Menstrual Cycle
Each month, the ovaries grow small sacs called follicles, which produce hormones to prepare the uterine lining for pregnancy. Prompted by follicle-stimulating hormone (FSH), one follicle becomes dominant. It then matures and, triggered by a surge in luteinizing hormone (LH), ruptures to release an egg during ovulation.
A follicular cyst forms when this process is disrupted. If the follicle fails to rupture and release its egg, it can accumulate fluid and enlarge into a cyst. This can happen due to hormonal imbalances, such as an absent LH surge, which prevents ovulation.
Associated Symptoms and Diagnosis
The majority of follicular cysts do not produce symptoms and are often discovered by chance during a routine pelvic exam. When a cyst grows large, it can cause a dull ache or a feeling of pressure or bloating in the lower abdomen. Some individuals might also experience breast tenderness or slight changes in their menstrual cycle length.
A healthcare provider may suspect a cyst during a pelvic exam, but a definitive diagnosis requires an imaging test. A pelvic ultrasound, especially a transvaginal one, provides clear images of the ovaries. This allows a doctor to confirm the cyst’s presence and assess its size, shape, and location.
Resolution and Medical Management
Most follicular cysts resolve spontaneously within one to three menstrual cycles without medical intervention. This approach is called “watchful waiting,” and a doctor may recommend a follow-up ultrasound to confirm the cyst has disappeared.
For cysts that persist or cause significant discomfort, hormonal contraceptives like birth control pills may be prescribed. These medications prevent ovulation, which stops new functional cysts from forming, though they do not shrink existing ones. Surgical removal is rarely necessary but might be recommended for very large, persistent, or painful cysts.
Potential Complications
Complications are uncommon but can occur. One issue is cyst rupture, where the cyst breaks open, causing a sudden, sharp pain in the lower abdomen and, in some cases, internal bleeding. The risk of rupture increases with the cyst’s size.
A rare but more serious complication is ovarian torsion. This happens when a large cyst causes the ovary to twist on its supporting tissues, cutting off its blood supply. Symptoms are severe and sudden, including intense pelvic pain, nausea, and vomiting, and require emergency surgery.