Fetal ovarian cysts

While most cases of fetal ovarian cysts are isolated and sporadic, there may be other associated anomalies (particularly in the gastrointestinal and genitourinary systems). These include:

• renal agenesis;
• polycystic kidneys;
• oesophageal atresia;
• duodenal atresia; and
• imperforate anus.

McKusick-Kaufman syndrome is a genetic condition associated with fetal ovarian cysts, alongside hydrometrocolpos, polydactyly and heart defects.

A fetal ovarian cyst is diagnosed if there is a fluid-filled sac greater than 2cm in diameter. Fetal ovarian cysts:

• can be a range of sizes;
• can lead to ovarian torsion if they are over 4cm in size (if this happens, or the cyst experiences haemorrhage, the appearance can be complex or solid);
• can cause polyhydramnios if they are over 6cm in size; and
• can lead to ascites if they rupture.

Most cases of fetal ovarian cysts are sporadic, with no genetic cause found. A few cases may be associated with genetic conditions, most commonly McKusick-Kaufman syndrome.

Fetal ovarian cysts are usually diagnosed on prenatal ultrasound scan.

Genomic testing is not usually performed for an isolated ovarian cyst. Where an ovarian cyst is found with other anomalies, testing may be considered (depending on the suspected conditions) and appropriate referrals made.

Where a fetal ovarian cyst is isolated, there is no risk of recurrence. If a genomic cause is found, the cause itself will suggest the inheritance pattern and recurrence. For example, in McKusick-Kaufman syndrome (an autosomal recessive condition), the risk of recurrence is 25%, or one in four subsequent pregnancies.

Antenatal management

• Patients should be referred to a fetal medicine unit for a further detailed ultrasound.
• Serial ultrasound scans should be offered every four weeks to assess the size of the cyst.
• If the cyst grows to more than 6cm, guided aspiration should be considered.
• Induction of labour aiming for a vaginal delivery should be offered from 38 weeks in a centre with appropriate neonatal care and access to paediatric surgery if required.

Postnatal management

• Many cysts are benign and resolve spontaneously.
• Occasionally surgery is needed to remove cysts if they persist or cause torsion.

For clinicians

• GeneReviews: McKusick-Kaufman syndrome
• NHS England: National Genomic Test Directory

References:

• Bascietto F, Liberati M, Marrone L and others. ‘Outcome of fetal ovarian cysts diagnosed on prenatal ultrasound examination: Systematic review and meta-analysis‘. Ultrasound in Obstetrics & Gynaecology 2016: volume 50, issue 1, pages 20–31. DOI: 10.1002/uog.16002

For patients

• The Newcastle upon Tyne Hospitals NHS Foundation Trust: My baby has an ovarian cyst on scan
• International Society of Ultrasound in Obstetrics and Gynaecology: Fetal ovarian cyst