Ovary pathology

IOTA (International Ovarian Tumor Analysis) Criteria

IOTA was developed by Dirk Timmerman, Lil Valentin and Tom Bourne to standardise terminology. It brings uniformity to descriptions of adnexal masses incorporating measurements and sonographic features. It endeavours to differentiate between benign and malignant masses. It follows simple rules based on mathematical models to estimate the risk of a mass being a malignancy.

Timmerman, D., Valentin, L., Bourne, T.H., Collins, W.P., Verrelst, H. and Vergote, I. (2000), Terms, definitions and measurements to describe the sonographic features of adnexal tumors: a consensus opinion from the International Ovarian Tumor Analysis (IOTA) group. Ultrasound Obstet Gynecol, 16: 500-505. https://doi.org/10.1046/j.1469-0705.2000.00287.x


Terms and Definitions to describe adnexal masses

Classification of ovarian lesions

To use the IOTA group’s calculator for ovarian cancer risk (NB this is not definitive)

Ovarian Cysts

  • Simple or Not 
  • haemorrhagic
  •  corpus luteal, 
  • ruptured, 
  • septated
  • Any mural nodules
  • Endometriomas

Ultrasound image- Progress of a haemorrhagic cyst. The haemorrhage may be resorbed or the cyst may collapse and no longer be visible. This image shows almost complete resorption of the haemorrhagic material.

Ultrasound image- A unilocular, simple ovarian cyst. Note the thin rim ovarian stroma overlying the cyst. It is crescent shaped.

Ultrasound image- Organising haemorrhage in an ovarian cyst.

Ultrasound image- By rolling the patient, you may be able to separate mural thickening from simple internal debris. The flattened surface on the 1st image is the clue that this is likely to be debris.

Ultrasound image- Endometriomas are cysts filled with blood arising from the ectopic endometrium.
It is commonly referred to as a “chocolate cyst”.

Endometriosis/ Endometrioma

  • Endometriosis is the ectopic existence of endometrial tissue.
  • Generally endometriosis sites are too small to be resolved with ultrasound, however occasionally a larger accumulation may result in the slow formation of a complex adnexal cyst called an endometrioma.
  • This cyst is filled with old blood seen as low grade homogeneous echoes.

Ultrasound image- Endometriomas are cysts filled with blood arising from the ectopic endometrium.
It is commonly referred to as a “chocolate cyst”.

Ultrasound image- An ovarian endometrioma with an adjacent follicle.
Differential diagnosis is a dermoid tumour of the ovary.

A large adnexal endometrioma.
Ultrasound image courtesy of Sr J Ragno.
Tuncurry Australia.

Ultrasound image -An endometrioma on the broad ligament, immediately between the uterus and ovary.

Ovarian Solid Tumours


A dermoid is a benign cystic teratoma, which is a tumour descending from germinal cells. It usually occurs in young women (20-30yrs) and represents 1 in 5 ovarian tumours. They are bilateral in approximately 10% cases. On histologic examination, lipidic substance, hair, sebaceous secretions, hair follicles, and eggshell calcifications are seen in 50% of cases; real organoid structures (teeth, fragments of bone) in 30% of the cases.

Teratomas are a form of germ cell tumor containing elements from all 3 embryonic germ layers, ie, ectoderm, endoderm, and mesoderm.

Symptoms may include abdominal and pelvic pain, and, in 15% of cases, the symptoms are associated with menstrual abnormalities. Torsion is the most common complication, whereas rupture and suppuration are uncommon. Malignant degeneration occurs rarely.

A small echogenic lesion is present in the left ovary on this trans abdominal ultrasound.

A transvaginal ultrasound confirmed the finding and the homogenous texture. This was proven to be a small dermoid tumour.

Ultrasound image- Dermoid is seen here as an echogenic/mixed mass and posterior shadowing. There is no vascularity within the tumour.

Ultrasound image- Round Calcification. This could be the result of an old necrotic haemorrhagic cyst or corpus albicans.

Ultrasound image- An ovary with a mass of unknown origin. The sonographer was suspicious of fat and thus a dermoid, so a CT was suggested.

A CT was done on the same patient to determine if there was a dermoid. The CT confirmed the presence of fat within the mixed lesion.

Ovarian Cancer

  • Neoplastic cysts arise by inappropriate overgrowth of cells within the ovary and may be malignant or benign.
  • Malignant neoplasms may arise from all ovarian cell types and tissues. By far, the most frequent are those arising from the surface epithelium (mesothelium), and most of these are partially cystic lesions.

Ovarian tumours form a complex group of malignant lesions.

Divided on the basis of their cell of origin into 4 major groups.
1. Tumours of the surface (germinal) epithelium. (65-75%)
2. Tumours of the germ cells. (15-20%)
3. Tumours of the sex cord stromal cells. (5-10%)
4. Nonspecific tumours of ovarian stroma or metastases from other organs. (5-10%)

CA 125

Measures a protein that is produced by ovarian tumour cells.
Elevated in 50% early stage cancer , 85% with advanced cancer.
CA 125 level of 35 cutoff point. 99% healthy women < than 35.
Focus is not on individual values but a trend in values.
Can be elevated in benign inflammatory conditions, diverticulitis , endometriosis, uterine fibroids.

Epithelial Cancer Classifications


Arise from the surface of the ovary
Most common ovarian cancer 65-75%
Fallopian Tube Cancer and Primary Peritoneal Cancer are also included within this designation

All tumours of the surface epithelium are adenocarcinomas.
Then classified as:
a) Serous – secrete clear watery fluid. Cystic. Most common form.
b) Mucinous – secrete mucin. Cystic.
c) Endometrioid – resemble endometrial glands and do not secrete anything , are solid. Always malignant.

Cystadenoma (serous/mucinous)- Benign

Cystadenocarcinoma (serous/mucinous)-Malignant

Ultrasound image- Serous Cystadenocarcinoma.

  • It contains cystic and solid components.
  • The mural nodules are seen arising from the septations.

Ultrasound image- Mucinous Cystadenocarcinoma

  • These are not as common as a serous cystadenocarcinoma. 
  • They can be difficult on ultrasound to differentiate. 
  • They usually have multiple cystic spaces and get extremely large >10cm.

Ovarian serous cystadenocarcinoma.

25% of serous tumours are malignant.
50-60% of ALL malignant ovarian tumours.
Most frequently in peri or post menopausal women.
50% are bilateral
15-20% involvement of BRCA genes (Am J Surg Pathol 2016;40:404)
A significant proportion arise in the fallopian tube and spread to the ovaries and peritoneum 

Mucinous Cystadenocarcinoma


  • Huge cystic mass
  • Multiloculated
  • Papillary projections
  • Echogenic material
  • Similar appearance to serous cystadenocarcinoma.
  • Tumour capsule rupture – spread of mucin secreting cells fill peritoneal cavity with gelatinous material – Pseudomyxoma peritonei – very rare.

Mucinous cystadenocarcinoma.

This is a transabdominal approach of the left ovary. It looks suspicious with the irregular walls and multiple solid (papillary) projections. A Transvaginal scan was done to see if it could give any more information

Ultrasound image of the mucinous cystadenocarcinoma by transvaginal scan gives an identical appearance.

There was a low resistive index on doppler assessment which further enhanced the suspicion that it was more likely a malignant mass rather than benign.


  • Solid Malignant Tumours.
  • 85% unilateral.
  • Composed of glands that represent endometrial glands.
  • 10-50% develop from endometriosis.
  • 20% of cases there is a uterine endometrial adenocarcinoma as well.
  • May occur in the setting of Lynch syndrome (Gynecol Oncol 2018;150:92, Am J Surg Pathol 2014;38:1173)
  • Clear cell tumour is a variant of endometrioid tumour

Pathology Findings:

Endometrioid adenocarcinoma Grade 2.   
Left ovary shows features of endometriotic cyst with atypical lining showing areas amounting to adenocarcinoma. There was no invasion of the cyst wall or surface of cyst .
Both fallopian tubes, cervix , omentum, left pelvic side wall nodule showed NO malignancy.
Uterus – mild chronic endometritis , adenomyosis and endometriosis.

Endometrioid Adenocarcinoma 

Minimal vascularity seen within the septations.

Ovarian Clear Cell Ovarian Tumour

Patients with clear cell carcinoma are younger, tend to present at an early stage, and their tumours are commonly associated with endometriosis which is a direct precursor of clear cell carcinoma.

Ultrasound image- Atypical Ovarian Clear Cell ovarian Tumour.

Ultrasound image- Note there is very little vascularity within the lesion. This could easily have been misdiagnosed as a pedunculated fibroid.

Malignant Germ cell tumours 

Starts in the egg cells – (95% are benign cystic teratomas)
5 % germ cell tumours are malignant
2-3 % of ALL malignant ovarian tumours.
Most common ovarian malignancy in children and young adults.
Subtypes : Dysgerminomas and Yolk sac tumours are nearly always malignant.
Elevated alpha-feto protein and Bhcg are found in tumours that contain a yolk sac.
80 % Germ cell tumours have increased serum lactic dehydrogenase isoenzyme.

Ultrasound Appearance: Solid Right adnexal mass .
Smooth external contour with echogenic solid tissue with several small cystic spaces.
Hypoechoic rim of tissue surrounding mass.
Appearances could be consistent with a germ call tumour or dysgerminoma.
Correlation with Tumour markers including a LDH level and histological correlation would be of value.

Polycystic Ovarian Syndrome (PCOS)

Importantly, ultrasound cannot exclude PCOS and should be used as a complimentary examination to assist in the diagnosis and help exclude other causes of symptoms. 50% of cases will have normal ultrasound appearances.

  • PCOS is a metabolic disorder resulting in a hypo or an-ovulatory state.
  • The pathophysiology is complex and varied between patients with the exact aetiology unknown.

To understand polycystic ovarian syndrome the following reference explains the guidelines followed internationally.

International evidence based guideline for the assessment and management of polycystic ovary syndrome.
Copyright Monash University,
Melbourne Australia 2018

International PCOS Guidelines

Ultrasound Criteria for Polycystic ovary diagnosis

Recommendations for ultrasound assessment of PCOS

Transvaginal ultrasound scan of a patient with proven polycystic ovarian syndrome (PCOS).

The bulky, rounded appearance with multiple (>20) follicles is typically seen.

Ultrasound image- Transvaginal view of the same ovary. Note that the multiple follicles can be scattered and do not need to be the stereotypical ‘string of pearls’ around the periphery. The volume is >10cc.

Ultrasound image- Polycystic Ovary

Ultrasound image- This is the same patient with multiple small atretic follicles.

Ovarian Hyperstimulation Syndrome (OHSS)

OHSS is an inherent complication risk with Assisted reproductive therapy. It is characterised by markedly enlarged multicystic ovaries following gonadotropin treatment.



  • Grade 1 – Abdominal distention and discomfort
  • Grade 2 – Grade 1 disease plus nausea, vomiting, and/or diarrhea plus ovarian enlargement from 5-12 cc

Moderate OHSS

  • Grade 3 – Features of mild OHSS plus ultrasonographic evidence of ascites

Severe OHSS

  • Grade 4 – Features of moderate OHSS plus clinical evidence of ascites and/or hydrothorax and breathing difficulties.
  • Grade 5 – All of the above plus a change in the blood volume, increased blood viscosity due to hemoconcentration, coagulation abnormalities, and diminished renal perfusion and function
    REF: Golan A, Ron-el R, Herman A, et al. Ovarian hyperstimulation syndrome: an update review. Obstet Gynecol Surv. Jun 1989;44(6):430-40.ECTOPIC PREGNANCY

Ovarian Tumors Benign:

  • Cystadenoma (Serous and Mucinous)
  • Dermoid (benign cystic teratoma)

Because these are germ cell tumors derived from ectodermal cells, they characteristically contain skin, sebaceous glands, hair, teeth and fat. 

Malignant: Cystadenocarcinoma (Serous and Mucinous)


Pouch of Douglas

  • Fluid
  • Pus
  • Blood
  • Pelvic inflammatory disease-PID

May be indicated by abnormal vaginal, bleeding or discharge.

  • Cysts (Mesenteric)

Usually embryologic remnants.

Pelvic Venous Congestion or Pelvic Congestion Syndrome (PCS)

Vascular and relative anatomy of the uterus and surrounds.

Ultrasound image- Prominant pelvic varices almost surround the ovary. Marked retrograde kaleidoscope flow is seen with pelvic straining.

Ultrasound image- Ask the patient to strain. The incompetent pelvic veins will dilate and rapidly fill with flow.

“Chronic pelvic pain is a common and disabling condition affecting women of childbearing age. A specific diagnosis for the condition is often difficult, and referred pain from the abdominal viscera, neurogenic and psychogenic factors have all been implicated, as have pelvic conditions such as endometriosis, pelvic inflammatory disease and ovarian cysts; no diagnosis is made in 60% of patients. Pelvic congestion syndrome (PCS), the presence of varices of the pelvic veins, has been shown to be the underlying aetiology in a significant proportion of patients with chronic pelvic pain; the development of these varices is caused by a combination of endocrine and mechanical factors. Given the positional nature of these varices, they are rarely diagnosed with conventional methods such as B-mode ultrasound and diagnostic laparoscopy. Diagnosis is best made with selective ovarian venography, although newer, non-invasive methods such as magnetic resonance imaging and duplex ultrasound are increasingly gaining favour. Pelvic varices are eminently treatable, either using ovarian suppression or by the ligation or embolization of the pelvic veins.

“REF: Phlebology. 2007;22(3):100-4. Pelvic congestion syndrome: chronic pelvic pain caused by ovarian and internal iliac varices. Author Liddle AD, Davies AH May be associated with vulval, groin or leg varices (but can occur without visible signs).Is a cause of chronic pelvic ache/pains and is often poorly diagnosed. Links:Pelvic congestion syndrome(pelvic venous incompetence): impact of ovarian and internal iliac vein embolotherapy on menstrual cycle and chronic pelvic pain.

Fallopian Tubes

  • PID
  • Pyosalpynx
  • Hydrosalpynx
  • Cyst
  • Ectopic pregnancy
  • Endometriosis


This transabdominal image clearly shows an anechoic tubular structure in the Right adnexa.

This is a TV scan showing a dilated fallopian tube coursing laterally around the right ovary.

Tubo-ovarian Abscess

The ovary is seen posterior to the enlarged fallopian tube filled with fluid and infected debris.

The infection may produce gas which is shown in this image as reverberation artifact.

Tubal Ectopic Pregnancy

The rounded isoechoic mass seen anterior to the left ovary must be suspicious for an ectopic pregnancy.

An ectopic pregnancy usually has vascularity.

Femoral Hernia with Ovary

Ultrasound image- Ovary is herniating into the femoral canal

Bowel Pathology

Whilst scanning the adnexae, be aware of the possibilty of bowel pathology presenting itself.


  • Bowel cancers
  • Diverticulitis

Ultrasound image- A transvaginal view demonstrating marked thickening and hyperaemia of the bowel mucosa. The normal thickness muscle layer is seen as a hypoechoic ring.

Posteriorly there is protrusion of the mucosa through the muscular layer consistant with diverticular disease.

Ultrasound image- Longitudinal view of the same segment of bowel.

The markedly increased vascularity confirms the acute inflammation rather than merely faeces.


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