Benign Ovarian Tumours

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Ovarian tumours can be divided into three main groups:

  • Functional
  • Benign
  • Malignant

In relative frequency, functional cysts account for about 24% of all ovarian cysts, benign cysts 70% and malignant 6% (see separate article Ovarian Carcinoma). See also separate article Ovarian Tumours and Fibroids in Pregnancy.

Benign epithelial neoplastic cysts (60% of benign ovarian tumours)

  • Serous cystadenoma:
    • Develop papillary growths which may be so prolific that the cyst appears solid.
    • They are most common in women aged between 40-50 years.
    • About 15-25% are bilateral and about 20-25% are malignant.
  • Mucinous cystadenoma:
    • The most common large ovarian tumours which may become enormous.
    • They are filled with mucinous material and rupture may cause pseudomyxoma peritonei. They may be multilocular.
    • They are most common in the 20-40 age group. About 5-10% are bilateral and around 5% will be malignant.

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Benign neoplastic cystic tumours of germ cell origin

  • Benign cystic teratoma; rarely malignant.
  • They arise from primitive germ cells.
  • A benign mature teratoma (dermoid cyst) may contain well-differentiated tissue, eg hair, teeth.
  • 20% are bilateral.
  • They are most common in young women.
  • Poorly differentiated, malignant teratomas are rare.

Benign neoplastic solid tumours

  • Fibroma (less than 1% are malignant); small, solid benign fibrous tissue tumours. They are associated with Meigs' syndrome and ascites.
  • Thecoma (less than 1% are malignant).
  • Adenofibroma.
  • Brenner's tumour:
    • Rare ovarian tumours displaying benign, borderline or proliferative, and malignant variants.
    • Over 95% are benign and more than 90% are unilateral.
    • They may be associated with mucinous cystadenoma and cystic teratoma.
  • Benign ovarian tumours occur in 30% of females with regular menses (eg luteal cysts as incidental findings on pelvic scans) and 50% of females with irregular menses.
  • Predominantly they occur in premenopausal women; they may also occur perinatally.
  • Benign ovarian tumours are uncommon in premenarchal and postmenopausal women.
  • Benign neoplastic cystic tumours of germ cell origin are most common in young women. They account for 15-20% of all ovarian neoplasms.

Risk factors

  • Asymptomatic - chance finding (eg on bimanual examination or ultrasound).
  • Dull ache or pain in the lower abdomen, low back pain.
  • Torsion or rupture may lead to severe abdominal pain and fever.
  • Dyspareunia.
  • Swollen abdomen, with palpable mass arising out of the pelvis, which is dull to percussion and does not disappear if the bladder is emptied.
  • Pressure effects, eg on the bladder, causing urinary frequency, or on venous return, causing varicose veins and leg oedema.
  • Torsion, infarction or haemorrhage:
    • Cause severe pain.
    • Torsion may be intermittent, presenting with intermittent episodes of severe pain.
  • Rupture:
    • Rupture of a large cyst may cause peritonitis and shock.
    • Rupture of mucinous cystadenomas may disseminate cells which continue to secrete mucin and cause death by binding up the viscera (pseudomyxoma peritonei).
  • Ascites - suggests malignancy or Meigs' syndrome.
  • Endocrine - hormone-secreting tumours may cause virilisation, menstrual irregularities or postmenopausal bleeding. This is uncommon though.
  • Pregnancy test (uterine or ectopic pregnancy).
  • FBC - infection, haemorrhage.
  • Urinalysis - if there are urinary symptoms.
  • Ultrasound - a pelvic ultrasound is the single most effective way of evaluating an ovarian mass. Transvaginal ultrasonography is preferable due to its increased sensitivity over transabdominal ultrasound.
  • CT or MRI scan - usually required only if ultrasound results are not definitive or if intra-abdominal pathology is suspected.
  • Diagnostic laparoscopy may be performed in some cases.
  • Fine-needle aspiration and cytology may be used to confirm the impression that a cyst is benign.
  • Cancer antigen 125 (CA-125):[3]
    • CA-125 does not need to be done in premenopausal women who have had an ultrasound diagnosis of a simple ovarian cyst made.
    • CA-125 is unreliable in differentiating benign from malignant ovarian masses in premenopausal women because of the increased rate of false positives and reduced specificity.
    • CA-125 is primarily a marker for epithelial ovarian carcinoma and is only raised in 50% of early-stage disease.
    • When serum CA-125 levels are raised, serial monitoring of CA-125 may be helpful, as rapidly rising levels are more likely to be associated with malignancy than high levels which remain static.
    • If serum CA-125 assay is more than 200 units/mL, discussion with a gynaecological oncologist is recommended.
    • Elevated in over 90% of patients with advanced ovarian carcinoma and in 50% of patients with early-stage ovarian disease.
    • CA-125 is not specific for ovarian cancer and may be elevated in a number of other malignancies, menstruation, endometriosis, pregnancy, benign ovarian tumours and pelvic inflammatory disease.
    • The main use of CA-125 is in assessing response over time to treatment for malignancy.
  • Lactate dehydrogenase (LDH), alpha-fetoprotein (AFP) and hCG should be measured in all women under the age of 40 with a complex ovarian mass because of the possibility of germ cell tumours.

Risk of Malignancy Index (RMI)

  • There are different risk of malignancy scores which can be used to assess an ovarian mass.[4]
  • The RMI I is the most effective for women with suspected ovarian cancer. This is also recommended by the National Institute for Health and Clinical Excellence (NICE) guideline on ovarian cancer.[5] It should not be used for premenopausal women though.
  • RMI I combines three presurgical features: serum CA-125 (CA-125); menopausal status (M); and ultrasound score (U).
  • The RMI is a product of the ultrasound scan score, the menopausal status and the serum CA-125 level (IU/mL) as follows:
    RMI = U x M x CA-125.
    • The ultrasound result is scored 1 point for each of the following characteristics: multilocular cysts, solid areas, metastases, ascites and bilateral lesions. U = 0 (for an ultrasound score of 0), U = 1 (for an ultrasound score of 1), U = 3 (for an ultrasound score of 2-5).
    • The menopausal status is scored as 1 = premenopausal and 3 = postmenopausal.
    • Serum CA-125 is measured in IU/mL.

Many patients with simple ovarian cysts based on ultrasound findings do not require treatment.

Expectant management[6]

  • Women with small (less than 50 mm diameter) simple ovarian cysts generally do not require follow-up, as these cysts are very likely to be physiological and almost always resolve within three menstrual cycles. [7]
  • Women with simple ovarian cysts of 50-70 mm in diameter should have yearly ultrasound follow-up and those with larger simple cysts should be considered for either further imaging (MRI) or surgical intervention.[8] In a postmenopausal patient, a persistent simple cyst smaller than 5 cm in dimension in the presence of a normal CA-125 value may be monitored with serial ultrasonography examinations.
  • However, ovarian cysts that persist or increase in size are unlikely to be functional and may need surgical management.

Oral contraceptives

  • The oral contraceptive pill is not recommended, as its use has not been shown to promote the resolution of functional ovarian cysts.[9]


  • If conservative measures fail or criteria for surgery are met, surgical therapy for benign ovarian tumours is generally very effective and provides a cure with minimal effect on reproductive capacity.
  • Persistent simple ovarian cysts larger than 5-10 cm, especially if symptomatic, and complex ovarian cysts should be considered for surgical removal.
  • In children and younger women (wishing to preserve maximum fertility), cystectomy may be preferable to oophorectomy.[10]
  • Laparoscopic surgery for benign ovarian tumours is associated with reduced risk of any adverse effect of surgery, reduced pain, and fewer days in hospital compared with laparotomy, in the small number of studies identified. There was no difference between the procedures with regard to outcomes of fever, postoperative infections and tumour recurrence.[11][12]
  • Ovarian torsion:[13]
    • Usually initially treated by laparoscopy with uncoiling of the affected ovary and possible oophoropexy.
    • Salpingo-oophorectomy may be indicated if there is severe vascular compromise, peritonitis or tissue necrosis.
  • Immediate surgical intervention is indicated for a haemorrhagic cyst.
  • Laparoscopy will need to be upgraded to laparotomy when malignancies are discovered.
  • Pseudomyxoma peritonei is treated by surgical debulking.
  • Torsion of an ovarian cyst can occur.
  • Haemorrhage is more common for tumours of the right ovary.
  • Rupture of an ovarian cyst can occur.
  • Infertility can occur as a result of ovarian tumours or their treatment.
  • This is variable and depends on the type and size of tumour, associated complications and patient's age.
  • Most small ovarian cysts in premenopausal women will resolve spontaneously.
  • Ovarian torsion: if operated within six hours of onset of symptoms, tissue will usually remain viable.
  • Prognosis of surgically removed cysts ultimately depends on the histology.

Further reading & references

  1. Bulun SE; Endometriosis. N Engl J Med. 2009 Jan 15;360(3):268-79.
  2. Hennessy BT, Coleman RL, Markman M; Ovarian cancer. Lancet. 2009 Oct 17;374(9698):1371-82. Epub 2009 Sep 28.
  3. Sturgeon CM, Lai LC, Duffy MJ; Serum tumour markers: how to order and interpret them. BMJ. 2009 Sep 22;339:b3527. doi: 10.1136/bmj.b3527.
  4. Obeidat BR, Amarin ZO, Latimer JA, et al; Risk of malignancy index in the preoperative evaluation of pelvic masses. Int J Gynaecol Obstet. 2004 Jun;85(3):255-8.
  5. Ovarian cancer - the recognition and initial management of ovarian cancer; NICE Clinical Guideline (April 2011)
  6. Helm CW, Ovarian Cysts, Medscape, Apr 2011
  7. Management of Suspected Ovarian Masses in Premenopausal Women, Royal College of Obstetricians and Gynaecologists (December 2011)
  8. Levine D, Brown DL, Andreotti RF, et al; Management of asymptomatic ovarian and other adnexal cysts imaged at US: Society Radiology. 2010 Sep;256(3):943-54. Epub 2010 May 26.
  9. Grimes DA, Jones LB, Lopez LM, et al; Oral contraceptives for functional ovarian cysts. Cochrane Database Syst Rev. 2011 Sep 7;9:CD006134.
  10. Hernon M, McKenna J, Busby G, et al; The histology and management of ovarian cysts found in children and adolescents BJOG. 2010 Jan;117(2):181-4.
  11. Medeiros LR, Fachel JM, Garry R, et al; Laparoscopy versus laparotomy for benign ovarian tumours. Cochrane Database Syst Rev. 2005 Jul 20;(3):CD004751.
  12. Medeiros LR, Stein AT, Fachel J, et al; Laparoscopy versus laparotomy for benign ovarian tumor: a systematic review and meta-analysis. Int J Gynecol Cancer. 2007 Aug 10.
  13. Fleischer AC et al, Ovarian Torsion, Medscape, Sep 2011

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Colin Tidy
Current Version:
Peer Reviewer:
Dr John Cox
Document ID:
1855 (v22)
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