Endometrioma

An endometrioma is an ovarian cyst lined by endometrial tissue and filled with thick, dark brown, degraded blood ("chocolate fluid"). It is a manifestation of ovarian endometriosis.

It occurs in 17 to 44 percent of women with endometriosis and in 1 to 3 percent of all reproductive age women. It is bilateral in about 30 to 50 percent. Its presence indicates more severe disease, with deep infiltrating endometriosis and adhesions in over 50 percent.

It develops by invagination of ovarian cortex with a superficial implant, by metaplasia, or by transformation of a haemorrhagic corpus luteum.

Complications:

• rupture (acute peritonitis)
• infection and abscess
• reduction in ovarian reserve (by disease and by surgery)
• infertility
• rarely, malignant transformation to clear cell or endometrioid carcinoma (below 1 percent). Risk factors are age above 45, size above 9 cm, rapid growth and solid papillary nodules with flow.

• Chronic pelvic pain, dysmenorrhoea, deep dyspareunia, dyschezia and dysuria around menses; many are asymptomatic.
• Subfertility.
• Acute pain at rupture or leakage; peritonism and fever with infection.
• Adnexal mass that is tender, fixed and with a thickened uterosacral ligament on examination; a retroverted fixed uterus.
• Large endometriomas cause pressure symptoms.

• Transvaginal ultrasound: a unilocular cyst with homogeneous low level ("ground glass") echoes, no internal vascularity (Doppler), thick wall, sometimes small echogenic foci in the wall, and multilocular in some; "kissing ovaries" (ovaries adherent behind the uterus) indicate severe disease.
• MRI: T1 hyperintense and T2 hypointense ("shading") with fat suppression; best to differentiate from haemorrhagic cyst and for deep disease and malignancy features.
• CA-125 is often elevated (mild to moderate) and is not diagnostic; the risk of malignancy is estimated using ultrasound features (ADNEX or IOTA rules).
• Follow up scans at 6 to 8 weeks distinguish a haemorrhagic cyst (resolves) from an endometrioma (persists).
• Laparoscopy with histology confirms the diagnosis; assess for deep endometriosis (rectal, bladder, ureter) with MRI or transrectal ultrasound.
• Anti-Müllerian hormone and antral follicle count to assess ovarian reserve before treatment.

Management is individualised according to symptoms, size, age, fertility desire, ovarian reserve and previous surgery.

Medical treatment is for pain, and to reduce recurrence after surgery. It does not eliminate the cyst, though it may reduce it by 10 to 30 percent.

• Dienogest 2 mg orally daily continuously. It also reduces cyst size by about 40 to 50 percent over 6 months.
• Combined oral contraceptive, continuous or cyclic (ethinylestradiol 30 micrograms with a progestogen), with continuous use for 3 to 6 months or longer.
• Other progestogens: norethisterone acetate 5 mg daily (up to 15 mg), medroxyprogesterone acetate 30 mg daily or depot 150 mg every 3 months, and a levonorgestrel intrauterine system.
• Gonadotrophin releasing hormone agonists: leuprolide 3.75 mg monthly intramuscular or goserelin 3.6 mg subcutaneously monthly, up to 6 months. Add back therapy (norethisterone 1 to 2.5 mg daily or oestrogen progestogen) protects bone.
• Oral antagonists: elagolix 150 mg daily or 200 mg twice daily, or relugolix combination 40 mg with estradiol 1 mg and norethisterone 0.5 mg daily.
• Non-steroidal anti-inflammatory drugs for pain (ibuprofen 400 mg every 8 hours; naproxen 500 mg every 12 hours).
• Postoperative medical suppression (dienogest or the combined pill) for at least 18 to 24 months reduces recurrence from about 30 to 40 percent to below 10 percent.

Surgical treatment is indicated for pain unresponsive to medical therapy, cyst above 4 to 5 cm, rapid growth, uncertainty about the diagnosis or suspicion of malignancy, torsion and infection. It is also indicated pre-IVF in selected cases with access difficulty or pain.

• Laparoscopic cystectomy (stripping of the cyst wall) is preferred over drainage and ablation. It lowers recurrence (about 6 to 20 percent versus 30 to 50 percent) and improves spontaneous pregnancy rates (about 60 percent versus 25 percent).
• Technique: identify the cleavage plane, strip the wall with atraumatic traction and counter traction, and use sutures or minimal bipolar energy for haemostasis. This minimises damage to the cortex and ovarian reserve. A fall in anti-Müllerian hormone of about 30 percent is typical, more in bilateral surgery or large cysts.
• Combined excision and ablation (the double layer technique) for larger cysts, with excision of the wall near the hilum replaced by ablation.
• Aspiration of the cyst alone has a recurrence of over 80 percent and is not advised except in IVF at oocyte retrieval.
• Oophorectomy in women with completed families, recurrent disease and severe adhesion, or suspicion of malignancy.
• Pre-operative GnRH analogue for 2 to 3 months in some women reduces size but is not required.
• In women planning IVF, surgery does not improve IVF success and may reduce ovarian response. Conservative management is often chosen for asymptomatic endometriomas below 4 to 5 cm.
• Surgery before IVF is considered when the cyst is above 5 to 6 cm, suspicious, painful, or obstructs follicle access. Surgery by an experienced surgeon, and prompt IVF afterwards (within 6 to 12 months), maximises results.
• Infertility: after surgery in minimal-to-mild disease, try spontaneous conception for 6 to 12 months. Otherwise IVF.
• Surveillance of unoperated endometriomas: ultrasound every 6 to 12 months for size and change. Surgery or MRI for growth, new solid components or vascular papillary projections.
• Recurrent endometriomas after previous surgery: medical treatment preferred. Repeat surgery lowers ovarian reserve.
• Pregnancy: endometriomas may decidualise (mimicking malignancy) and are generally observed.