Bilateral septated cystic hygroma at 12+3 weeks — karyotyping showed trisomy 21 (Photo: Podobnik P, Meštrović T, Podobnik M, Lončar I, Bertović-Žunec I, Kurdija K, Jelčić D, …Image: Podobnik P, Meštrović T, Podobnik M, Lončar I, Bertović-Žunec I, Kurdija K, Jelčić D, Srebreniković Z, Podobnik-Šarkanji S. (Genes, 2025) · CC BY 4.0 · Source · cropped
Image: Mazza GR, Rau AR, De Zoysa MY. (Case reports in genetics, 2025) · CC BY 4.0 · Source
Ultrasound
Massively increased nuchal translucency of 14 mm with a cystic hygroma at first-trimester screening (Photo: Subbaraj C, Guma M. (Cureus, 2025), open access, CC BY 4.0)Image: Subbaraj C, Guma M. (Cureus, 2025) · CC BY 4.0 · Source · cropped
Middle cerebral artery Doppler with a peak systolic velocity of 1.91 MoM — pointing to fetal anaemia (Photo: Yanase Y, Sirilert S, Jatavan P, Pomrop M, Phirom K, Tongsong T. (Journal of …Image: Yanase Y, Sirilert S, Jatavan P, Pomrop M, Phirom K, Tongsong T. (Journal of clinical medicine, 2025) · CC BY 4.0 · Source · cropped
Image: Yanase Y, Sirilert S, Jatavan P, Pomrop M, Phirom K, Tongsong T. (Journal of clinical medicine, 2025) · CC BY 4.0 · Source · cropped
Ultrasound
Image: Almeida M, Campos M, Soares C, Godinho C, Brito M. (Cureus, 2025) · CC BY 4.0 · Source
Image: Yanase Y, Sirilert S, Jatavan P, Pomrop M, Phirom K, Tongsong T. (Journal of clinical medicine, 2025) · CC BY 4.0 · Source · cropped
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Definition
Definition and findings
A cystic hygroma represents an extreme variant of increased nuchal translucency and is associated with conditions such as Turner syndrome, trisomy 21 and 18, and Noonan syndrome.
A resolving cystic hygroma can later present as pterygium colli.
The diagnosis of hydrops fetalis requires evidence of fluid in at least two compartments, such as skin oedema >5 mm, ascites, pleural or pericardial effusion.
Aetiopathogenesis
Causes of hydrops fetalis
The classic immunological cause is a blood group incompatibility, most notably Rh and Kell incompatibility.
The majority of cases today have non-immune causes, such as cardiac malformations, tachyarrhythmias, or fetal anaemia, for example due to parvovirus B19.
The mnemonic PTORCH summarises important infectious causes, where P stands for Parvovirus B19.
Keep learning in the app
In the GynFuchs app you can learn Hydrops fetalis with flashcards, exam questions and image tasks (colposcopy, ultrasound, CTG) – free, in your browser or as an app.
Note: Learning content from the GynFuchs app (flashcards, exam questions, image cases) for medical education – not a treatment recommendation and no substitute for diagnosis or treatment decisions in individual cases. Treatment and management are deliberately not covered on this page.
Ultrasound
Ultrasound
Ultrasound
Ultrasound