Hydrops fetalis

Last revised by Tee Yu Jin on 29 Jan 2022

Hydrops fetalis is excessive extravasation of fluid into the third space in a fetus which could be due to heart failure, volume overload, decreased oncotic pressure, or increased vascular permeability. Hydrops is defined as the accumulation of fluid +/- edema involving at least two fetal components, which may manifest as: 

The estimated incidence is at ~1 in 2000 births although this can significantly vary according to different regions.

It is considered a prenatal form of cardiac failure. It was traditionally divided into two broad groups:

Accounts for a minority (~10%) of cases in present-day pregnancies 8, although historically accounted for a larger proportion of cases in the early to mid 20th century:

Accounts for a majority of cases and can arise from protean causes which include:

Sonographic features can be similar for both immune and non-immune hydrops and include:

The overall prognosis can be variable, dependent on the underlying cause.

The term hydrops fetalis comes from the Latin meaning edema of the fetus 6.

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Cases and figures

  • Case 1: with cystic hygroma
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  • Case 2
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  • Case 3
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  • Case 4
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  • Case 5: TORCH test positive
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  • Case 6: subcutaneous edema + pleural effusion
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  • Case 7: with cystic hygroma
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  • Case 8: in twin reversed arterial perfusion (TRAP) sequence
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