Corpus Luteum Cyst

A corpus luteum cyst forms when the corpus luteum fills with fluid or blood after ovulation and does not regress. It often produces progesterone, delaying menses.

• It may be haemorrhagic, with a lace-like or reticular ultrasound pattern.
• It is common in early pregnancy and in women on ovulation induction.
• It carries a higher risk of rupture and bleeding than other functional cysts.

Unilateral pelvic pain, delayed or irregular menses, spotting, and sudden pain with collapse if the cyst ruptures.

• Tender adnexal mass; tachycardia and low blood pressure with haemoperitoneum.
• Differential diagnosis: ectopic pregnancy, endometrioma, ruptured follicular cyst, ovarian torsion, tubo-ovarian abscess, appendicitis, dermoid cyst, ovarian cancer.
• Complications: rupture with haemoperitoneum, torsion, anaemia and, in anticoagulated women, massive bleeding.

Diagnosis is by transvaginal ultrasound after a pregnancy test, with exclusion of ectopic pregnancy.

• Pregnancy test; serum beta human chorionic gonadotrophin if positive.
• Transvaginal ultrasound: 3 to 6 cm cyst with a thick, crenated wall, internal lace-like echoes and a ring of colour flow; free fluid if ruptured.
• Haemoglobin and group and cross-match if bleeding is suspected.
• Rule out ectopic pregnancy when the test is positive and no intrauterine pregnancy is seen.
• Repeat ultrasound after 6 to 8 weeks.

Observe stable women, resuscitate if bleeding is heavy, and operate for ongoing bleeding or instability.

• Supportive: rest; heat to the abdomen; IV access and fluids in a woman with free fluid; monitor pulse and blood pressure.
• Pharmacological: paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); morphine 2.5 to 5 mg IV titrated every 5 minutes for severe pain; ibuprofen 400 mg oral 8-hourly with food (maximum 1.2 g in 24 hours) only if bleeding has stopped and the woman is not pregnant. Transfuse when haemoglobin is below 7 g/dL or in shock. Reverse anticoagulation if present.
• Procedures: observation for stable women; laparoscopy with evacuation of blood and cyst wall suturing or cystectomy, preserving the ovary, for ongoing bleeding, instability or severe pain.
• Special groups: in early pregnancy, the cyst supports progesterone production and usually regresses by 16 weeks; avoid removing it before 12 weeks unless torsion or heavy bleeding occurs, and give progesterone support if removal is needed (progesterone 200 mg vaginal at night until 12 weeks). Avoid ibuprofen from 28 weeks.
• Red flags: shock, falling haemoglobin, peritonism, positive pregnancy test with pelvic pain, anticoagulant use.
• Follow-up: ultrasound at 6 to 8 weeks; review of haemoglobin at 2 weeks.