Functional Ovarian Cyst

A functional ovarian cyst is a fluid-filled sac formed by the normal ovulatory cycle: a follicular cyst (follicle that does not rupture) or a corpus luteum cyst (luteal body that fills with fluid or blood).

• It is a common ovarian cyst in women of reproductive age.
• Most are simple, below 5 cm, and settle in 4 to 12 weeks without treatment.
• It does not occur after menopause, so a cyst found then is not functional.

Most women have no symptoms.

• Dull unilateral pelvic ache, pressure, delayed or irregular menses, dyspareunia, and sudden severe pain if the cyst bleeds, ruptures or twists.
• A tender adnexal swelling on bimanual examination, or a normal examination.
• Differential diagnosis: ectopic pregnancy, endometrioma, dermoid cyst, cystadenoma, ovarian torsion, tubo-ovarian abscess, hydrosalpinx, ovarian cancer, pedunculated fibroid.
• Complications: rupture, haemorrhage into the cyst, torsion, haemoperitoneum.

Diagnosis is by pregnancy test and transvaginal ultrasound.

• Pregnancy test (urine or serum human chorionic gonadotrophin) in every woman of reproductive age.
• Transvaginal ultrasound: anechoic, thin-walled, unilocular cyst, with no solid part or flow in the wall; a corpus luteum cyst may show a thick wall with a ring of flow.
• Full blood count if bleeding is suspected.
• CA-125 only if the cyst is complex, solid, or the woman is postmenopausal.
• Repeat ultrasound after 6 to 12 weeks if the cyst is above 5 cm or the picture is unclear.

Reassure and observe simple cysts, give analgesia, and operate only for complications or persistent cysts.

• Supportive: reassure; heat to the lower abdomen; avoid heavy exercise and sports with sudden twisting while the cyst is large.
• Pharmacological: paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours) and ibuprofen 400 mg oral 8-hourly with food (maximum 1.2 g in 24 hours) for 3 to 5 days.
• Procedures: observation for simple cysts below 5 cm (no follow-up needed), repeat ultrasound at 6 to 12 weeks for cysts of 5 to 7 cm, and MRI or surgery for cysts above 7 cm. Laparoscopic cystectomy for a cyst that persists beyond 3 months or enlarges, for torsion or rupture with instability.
• Special groups: in pregnancy observe, and avoid ibuprofen from 28 weeks. In postmenopausal women investigate with CA-125 and ultrasound because a functional cyst is unlikely.
• Red flags: sudden severe pain, vomiting, fever, shock, pain with a positive pregnancy test, cyst growth or new solid areas.
• Follow-up: repeat ultrasound at 6 to 12 weeks until the cyst resolves.