Ovarian Cysts

Ovarian cysts are defined as collections of fluid or semiliquid material, often walled off by a membrane, located in the ovary. These cysts are broadly categorized as either functional or neoplastic. Neoplastic ovarian cysts are subcategorized as either benign or malignant. When the cysts occur as a result of normal physiologic processes, they are called functional, whereas if there is abnormal growth of ovarian cells, the cyst is referred to as neoplastic. In women of reproductive age, neoplastic ovarian cysts are typically benign; however, the risk of malignancy increases in the postmenopausal period. While most ovarian cysts do not cause symptoms, some women report vague symptoms such as lower abdominal pain or abdominal fullness. Complications of functional cysts include torsion and rupture. Neoplastic cysts may be either benign or cancerous. A diagnosis of ovarian cancer requires consultation with a specialist because treatment involves coordination of surgery and chemotherapy. Treatment is dependent on the etiology of the ovarian cyst and may range from surgical intervention to supportive care only.

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Benign Cysts

Epidemiology and etiology

  • Follicular cyst
    • Most common ovarian mass in women of reproductive age
    • Unruptured graafian follicle that continues to grow
    • Characteristics:
      • Multiple
      • Variable size (normal follicles < 3 cm; pathologic follicular cysts are typically < 10 cm)
      • Lined with granulosa and theca cells
    • Associated with endometrial hyperplasia and hyperestrogenism
  • Corpus luteal cyst 
    • Following ovulation, follicles become corpus luteal cysts.
    • Secrete progesterone
    • Normal, physiologic structures in the second half of the menstrual cycle and 1st trimester of pregnancy
    • Secrete progesterone required to maintain the endometrium in pregnancy
    • Characteristics:
      • Unilateral
      • Typically, 2‒3 cm size (but can be up to 8 cm)
      • Uniloculated cysts, which can contain some internal debris.
  • Endometriomas 
    • Also called chocolate cysts
    • Arise from ectopic growth of endometrial tissue on the ovary 
    • A form of endometriosis

Clinical features

  • Usually asymptomatic if < 6 cm
  • Symptoms may include:
    • Pain
    • Peritoneal irritation
    • Delayed menses 
    • Vaginal bleeding
  • Follicular and corpus luteal cysts are rarely symptomatic if small and unruptured.
  • Endometriomas are much more likely to be symptomatic, regardless of size, typically presenting with:
    • Dysmenorrhea
    • Dyspareunia
    • Infertility


  • History and exam
    • Consistent clinical symptoms
    • Palpable adnexal mass on pelvic examination
  • Imaging
    • Ultrasonography:
      • Smooth, thin-walled
      • Anechoic
      • Large cysts with reticular echoes might represent hemorrhage within a corpus luteal cyst, which should be followed with a repeat ultrasound in 2‒3 months.
    • MRI:
      • Ovarian cysts show low signal intensity on T1-weighted images and high signal intensity on T2-weighted images because of the fluid content of the cyst. 
      • MRI usually reveals a thin and featureless wall that enhances the uptake of gadolinium. 
      • T2 shortening is not seen in corpus luteal cysts, in contrast to endometrial chocolate cysts.
  • Cancer antigen 125 (CA-125) blood test:
    • Only for postmenopausal women
    • Complex cysts and high CA-125 associated with increased risk of malignancy


  • Typically no treatment required unless complications occur:
    • Follicular cysts usually resolve spontaneously within 1–2 menstrual cycles.
    • Resolution occurs after cyst fluid resorption or spontaneous rupture.
    • Cysts that do not resolve require further investigation.
  • Use of oral contraceptives has not proved to be helpful.
  • Transvaginal ultrasonography may be required to monitor cyst changes.
  • Surgical removal (oophorectomy):
    • Indications:
      • Suspected ovarian torsion
      • Persistent adnexal mass
      • Suspected malignancy

Related videos

Neoplastic Cysts


Neoplastic masses are classified according to their cell of origin: epithelial cells, germ cells, and sex cord-stromal cells. Each has multiple histologic subtypes. Each subtype can be either benign or malignant.

  • Epithelial cell tumors
    • Most common type of malignant ovarian tumor
    • Histologic subtypes include:
      • Serous tumors
      • Mucinous tumors
      • Clear cell tumors
      • Endometrioid tumors
      • Undifferentiated tumors
    • Histology, rather than radiographic appearance, determines if tumor is benign, borderline, or malignant.
    • Typically affect middle-aged and elderly women
  • Germ cell tumors: teratomas
    • Arise from germ cells
    • Common in children and adolescents
    • Usually asymptomatic and discovered incidentally on pelvic exam
    • Called “dermoid cysts” because they often contain ectodermal components, such as teeth and hair
    • High risk of ovarian torsion
  • Benign sex cord-stromal tumors
    • Histologic subtypes:
      • Fibroma
      • Thecoma
      • Fibrothecoma
    • Arise from the stroma of the ovary
    • Common in middle-aged women
    • Associated with ascites and pleural effusions
  • Metastatic tumors
    • Endometrium
    • Breast
    • Colon
    • Cervix

Clinical features

  • Lower abdominal pain: acute-onset pain associated with ovarian rupture, torsion, or bleeding
  • Pelvic pain
  • Abdominal distention
  • Abdominal fullness, bloating
  • Indigestion
  • Heartburn
  • Early satiety
  • Painful intercourse
  • Irregular periods
  • Abnormal vaginal bleeding
  • Urinary frequency
  • Constipation
  • Leg swelling
  • Weight loss


  • Ultrasonography used to determine malignancy risk index:
    • Benign tumors:
      • Unilocular
      • Thin-walled
      • Papillary projections present
    • Malignant tumors:
      • Bilateral
      • Multinodular
      • Presence of papillary projections
      • Solid areas within the tumor
      • Presence of ascites
      • Abdominal involvement
  • Risk of malignancy index (RMI): 
    • Clinical tool used to determine risk of cancer for ovarian tumors and to guide management
    • Considers 3 features:  menopausal status, ultrasound score, and presence of CA-125 in serum
    • Higher RMI correlates with increased risk of malignancy.
  • MRI and CT scan features:
    • Heterogeneity
    • Faster contrast enhancement
    • Calcification
    • Multilocular cysts
Multiplanar CT demonstrating an ovarian cancer

Multiplanar CT demonstrating ovarian cancer

Image: “Multiplanar computed tomography scan demonstrating an ovarian cancer” by Subapriya Suppiah. License: CC BY 3.0


  • Surgical removal
  • Chemotherapy


Ovarian torsion

  • Definition: twisting of the ovary and fallopian tube
  • Epidemiology:
    • Correlated with larger ovaries (> 5 cm)
    • Occur more often in women of reproductive age because of menstrual cycle and formation of corpus luteal cyst
    • More common on the right side because the left adnexa is stabilized by the sigmoid colon
  • Pathophysiology:
    • Twisting initially causes venous and lymphatic obstruction, leading to ovarian congestion and swelling 
    • Evolves to arterial blockage
    • Results in ischemia and infarction 
    • Final stage is local hemorrhage and tissue necrosis
  • Clinical features: 
    • Pelvic mass
    • Nausea
    • Severe acute pelvic pain
    • Fever
    • Abnormal bleeding
  • Diagnosis:
    • Laparoscopy (gold standard)
    • Pregnancy test
    • Ultrasonography: most common finding is asymmetric enlarged ovary
    • CT scan
  • Treatment: detorsion via laparoscopic surgery
Twisted right ovarian cyst

Right ovarian torsion demonstrated by twisted pedicle and swollen ovary

Image: “Twisted right ovarian cyst” by Department of Pediatric Surgery, Division of Pediatric Urology, Cukurova University, Faculty of Medicine, Adana, Turkey. License: CC BY 3.0

Ruptured ovarian cyst

  • Clinical features: 
    • Unilateral lower abdominal pain
    • Onset of pain is acute and of moderate to severe intensity.
  • Diagnosis:
    • Pelvic ultrasonography: free fluid usually in the pouch of Douglas
  • Treatment: laparoscopic surgery

Clinical Relevance

  • Polycystic ovarian syndrome: heterogeneous multisystem endocrinopathy that is characterized by hyperandrogenism, ovarian dysfunction, and multiple cysts in the ovaries. The condition is also associated with metabolic syndrome, hyperinsulinemia, and insulin resistance. Diagnosis is one of exclusion, so other causes of abnormal uterine bleeding and hirsutism should be ruled out. Management includes attempting to restore normal ovulation through weight loss, oral contraceptive pills, and assistance with fertility.
  • Ovarian tumors: Sex-cord stromal tumors arising from the theca or granulosa cells within the ovary may secrete androgens or estrogens, respectively. Individuals may have signs of virilization, irregular menstrual cycles, or abnormal uterine bleeding. Initial treatment is surgical and based on the stage (if malignant).


  1. Miranda, A., MD, FACOG, Vasquez de Bracamonte, D., MD et al. (2016). Ovarian cysts: functional or neoplastic, benign or malignant? Retrieved June 17, 2021, from https://reference.medscape.com/features/slideshow/ovarian-cysts#page=1
  2. Horlen, C. (2010). Ovarian cysts: a review U.S. Pharmacist 35(7):1–4. Retrieved June 17, 2021, from https://www.medscape.com/viewarticle/726031_3
  3. Moolthiya, W., Yuenyao, P. (2009). The risk of malignancy index (RMI) in diagnosis of ovarian malignancy. Asian Pac J Cancer Prev 10:865–868. https://pubmed.ncbi.nlm.nih.gov/20162854/
  4. Mayo Clinic. Polycystic ovarian syndrome (PCOS). Retrieved June 18, 2021, from https://www.mayoclinic.org/diseases-conditions/pcos/symptoms-causes/syc-20353439

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