Ovarian cysts (adnexal cysts)

Classification

Functional Cysts

• The follicular cyst is unilocular, anechoic, smooth-walled, and usually resolves within two to three cycles.
• The corpus luteum shows a thick, highly vascularised wall with a 'ring of fire' on Doppler and an anechoic or haemorrhagic centre.
• The haemorrhagic cyst characteristically has a fine reticular fishnet pattern or a retracted clot without its own blood flow.

Dermoid and Endometrioma

• The mature teratoma is identified by the echogenic Rokitansky nodule, fat-fluid levels, and fine echogenic lines and dots from hair.
• The endometrioma appears on ultrasound as homogeneous and hypoechoic with ground-glass internal echoes and no blood flow in the internal components.
• Dermoids are particularly prone to torsion because their contents are dense and heavy.
• CA 125 is also elevated in endometriosis, which limits its diagnostic value in young women.

Diagnosis

Non-Ovarian Origin

• A hydrosalpinx shows a convoluted, anechoic tubular structure with incomplete septation and the 'cogwheel sign'.
• A tubo-ovarian abscess is a complex cystic-solid mass with fever, signs of inflammation, and cervical motion tenderness.
• A peritoneal inclusion cyst is identified by the fact that the ovary lies freely within the fluid and the wall is formed by the peritoneum.

What IOTA is

• IOTA acronym: The acronym IOTA stands for International Ovarian Tumour Analysis, a collaborative group for the standardised description of adnexal findings.
• Described features: The IOTA standard always describes size in three planes, internal structure, septa, solid components, papillary projections, ascites and vascularisation.

Easy Descriptors

• B-descriptor: A typical B-descriptor is, for example, the unilocular cyst with a smooth wall in a premenopausal woman.
• M-descriptor: A typical M-descriptor is, for example, ascites plus a solid tumour with vascularisation in a postmenopausal woman.

Simple Rules

• Structure: The Simple Rules consist of five benign and five malignant features that are weighed against each other.
• Benign features (B-rules): The benign features include unilocular cyst, solid component < 7 mm, acoustic shadows, smooth-walled multilocular tumour < 10 cm and no blood flow.
• Malignant features (M-rules): The malignant features include irregular solid tumour, ascites, at least four papillary projections, irregular multilocular-solid tumour > 10 cm and very strong blood flow.

Typical imaging findings

• Ultrasound: A roughly five-centimetre, completely anechoic structure with a smooth thin wall lies within the ovary. The tissue behind it is markedly brighter (posterior acoustic enhancement). No septa, no solid components, no papillary projections.
• Ultrasound: A round, anechoic structure with a smooth, thin wall, no solid components and no relevant internal echoes — the typical appearance of a simple (functional) ovarian cyst.

Keep learning in the app

Further reading (selection)

1. StatPearls: Ovarian Cyst (NCBI Bookshelf)
2. DocCheck Flexikon, Ovarialzyste

Cross-references