Hydrops

Hydrops is defined as fluid within two or more body spaces, for example:

• pericardial effusion
• pleural effusion/s
• ascites
• skin oedema.

• Non-immune (see Nonimmune Hydrops Fetalis [PDF, 389 KB], NZMFMN 2012)
• Immune (see RBC antibodies and thalassemia below).

As per Third-trimester ultrasound examination.

• Heart rate and rhythm to exclude fetal cardiac arrhythmia.
• MCA PSV (see New Zealand Obstetric Doppler Guideline [PDF, 3.7 MB], NZMFMN 2014b) to exclude fetal anaemia from maternal rhesus disease or other causes. Obtain the waveform when the fetus is quiescent and ideally at an angle of 0 degrees (but 30 degrees or less is acceptable). Chart on the appropriate graph (as per New Zealand Obstetric Doppler Guideline [PDF, 3.7 MB]).
• Document hydrops.

• Report general findings as per the third-trimester reporting guide.
• Report MCA PSV, comment on multiples of the median (MoM).
• Comment on hydrops/body cavity involvement.

If MCA PSV is elevated, then moderate to severe fetal anaemia is likely. This is an obstetric emergency, usually requiring intrauterine blood transfusion or delivery. Notify referrer to arrange Fetal Medicine or specialist referral immediately.

RBC antibodies and thalassemia in pregnancy

Women with maternal red cell antibodies or thalassaemia in pregnancy are at increased risk of fetal anaemia. Rhesus disease has been the most common, but a list is included below. Fetal Medicine review is recommended.

Frequency of scanning should be as per local Fetal Medicine / specialist unit recommendation.

Indications

• Fetal hydrops
• Rhesus alloimmunisation (RhD)
• Rhesus c
• Anti-Kell
• Anti-Fya or Anti-E (rarely)
• Thalassemia (alpha)
• Parvovirus infection can also present with hydrops and fetal anaemia.

These are the main risks for fetal anaemia. Please discuss any others with a Fetal Medicine / specialist unit.

Ultrasound examination

As per Third trimester ultrasound examination.

See also New Zealand Obstetric Doppler Guideline (PDF, 3.7 MB) (NZMFMN 2014b).

Additional views

• MCA PSV and chart on graph (see New Zealand Obstetric Doppler Guideline [PDF, 3.7 MB], NZMFMN 2014b).
• Assess for hydrops (fluid in two or more compartments, ie, pericardial effusion, pleural effusion, fetal ascites, skin oedema).
• Assess amniotic fluid.

Reporting guide and recommendations

• Report general findings as per the third-trimester reporting guide.
• Report MCA PSV, comment on MoM.
• Comment on hydrops/body cavity involvement.

If MCA PSV is elevated, then moderate to severe fetal anaemia is likely. This is an obstetric emergency, usually requiring intrauterine blood transfusion or delivery. Notify referrer to arrange Fetal Medicine or specialist referral immediately.