An appropriately experienced operator should perform a screening fetal echocardiogram on women at risk of fetal cardiac anomaly, ideally as part of the 19‑week anatomy scan.
A diagnostic fetal echocardiogram is a tertiary-level scan, often performed by a maternal fetal medicine (MFM) or paediatric cardiology service and is usually performed to assess a previously identified or suspected cardiac anomaly.
When a fetal cardiac anomaly is suspected on a routine 19-week anatomy scan, the images should be reviewed by an experienced operator, either locally or at a distant tertiary level, depending on local resources.
If cardiac anomaly is likely, the woman should be referred directly to the regional MFM centre for a diagnostic fetal echo.
If cardiac anomaly is unlikely but more certainty is required, a screening echo should be performed, as described below, by an appropriately trained operator.
Indications for detailed fetal echocardiography
- Suspected fetal cardiac abnormality (as above).
- Increased NT ≥3.5 mm at the 12+ week scan.
- Previous baby or direct family history of congenital cardiac abnormality.
- Maternal diabetes (insulin-dependent diabetes mellitus, IDDM, non-insulin dependent diabetes mellitus, NIDDM).
- Clinical risk factor for fetal cardiac abnormality, for example, maternal anti-epilepsy medication.
When views are technically suboptimal/limited, a follow-up scan should be booked at around 22–24 weeks.
Cine clips/sweeps are required if images are to be reviewed in Auckland, or if an anomaly is identified.
When using colour Doppler, the region of interest (ROI) should be minimised to maintain a frame rate of >25 Hz. The aliasing velocity should be set at 20–30 cm/s when interrogating venous flow and 50–60 cm/s otherwise.
- Transverse abdomen: document stomach and aorta to left and IVC to right
- Apical 4Ch view: document valves open and closed (with and without colour Doppler) and relative sizes of the ventricles
- 4Ch view transverse: interventricular septum (IVS) long and short axis, with and without colour
- Foramen ovale: colour view to show right-to-left flow
- Pulmonary veins: at least one left and one right seen entering left atrium, with colour
- LVOT: measure at aortic valve, non-colour and colour views
- RVOT: measure at pulmonary valve, non-colour and colour views
- RVOT and pulmonary arteries: measure both left and right proximal pulmonary artery (PA) diameters, plus colour views
- 3VT / arrow view: non-colour and colour view, showing aorta to the left (or right) of the trachea. Measure isthmus and obtain pulsed wave Doppler in the isthmus if small
- Assess aortic arch branching vessels and detect an aberrant origin of a subclavian artery if present, using colour Doppler
- IVC and SVC: colour views in long axis draining into right atrium
- Aortic arch: long axis without and with colour and showing cranial vessels
- Ductal arch: long or short axis with and without colour
- Ductus venosus
- Thymus gland
- Cardiac rate and rhythm
- Pericardial fluid >2 mm.
Cine clips or sweeps if external review is likely to be required, which may include:
- cine loop sweep from abdomen to the atria to assess for abdominal and atrial situs
- cine loop assessment of 4Ch heart view for assessment of relative size of ventricles, ventricular function, AV valve function (with and without colour) and to rule out VSDs (septum to outlet)
- cine loop sweeps from 4Ch view to outflow of great vessels, showing relationship of ventricle to great vessel and great vessel valves
- cine loop sweeps from 4Ch view to 3VT / arrow views (with and without colour)
- cine loop sweep of short axis of ventricles (with colour) to assess for VSD
- cine loop sweep of ductal and aortic arches (with and without colour).
These are the minimum cine clips required for fetal cardiology review; more should be done if required to illustrate pathology.
An irregular cardiac rhythm is frequently observed and is predominantly benign in the second trimester, due to premature atrial contractions. This can be documented by M‑mode on the atria and ventricle.
A sustained bradycardia (<110 bpm) or tachycardia (>180 bpm) requires referral.
Fetal arrhythmia with reduced fetal movements, hydrops, reduced observed fetal activity or other evidence of fetal compromise requires urgent referral.
For further information, see Fetal Arrhythmia (PDF, 531 KB) (NZMFMN 2015b).
Isolated muscular VSD
Small isolated muscular VSDs are common and usually have an excellent prognosis, with most spontaneously resolving later in pregnancy or in early neonatal life.
Recommend specialist review and diagnostic echo.
Recommend specialist review and diagnostic echo.
Common cardiac anomalies
See Cardiac anomalies for further information.
Reporting guide and recommendations
Minimum reporting requirements
- Clinical indication for the scan
- General pregnancy information, for example, dating information
- Cardiac anatomy assessment, and any limitations / anatomy incompletely visualised
- Abnormal cardiac findings and suspected diagnosis if appropriate.
Any cases of suspected cardiac anomaly should be referred for specialist review and diagnostic echo.
When the examination is incomplete, recommend a follow-up scan at 22–24 weeks if there is no suspected anomaly; otherwise prompt specialist referral is required.
- Fetal arrhythmia with reduced fetal movements, hydrops, reduced observed fetal activity or other evidence of fetal compromise (requires urgent referral)
- Suspected cardiac anomaly.