Fetal echocardiography is a detailed ultrasound that is performed after the detection of a potential cardiac abnormality during an obstetric ultrasound or in patients with a strong history of congenital cardiovascular disease. Additionally, women exposed to cardiac teratogens are usually advised to have this study. Not a screening procedure, fetal echocardiograms are most commonly performed in specialized facilities. The heart is imaged in numerous planes, using pulsed Doppler and M-mode tracings, similar to an ECG (see Cardiac Ultrasound). Valves and other cardiac structures are measured, and blood velocities and volumes are calculated. Optimal fetal echocardiographic studies are performed between 18 and 22 gestational weeks. Before 18 weeks, the fetal heart is too small, and after 22 weeks, image quality may be degraded by overlying structures.

1. Perform the fetal echocardiogram in the same manner as a routine obstetric ultrasound, which also requires similar patient preparation, although a full bladder is not necessary. The pregnant patient lies on her back with the abdomen exposed. A couplant (ultrasound gel) is applied to the skin, and a transducer is moved across the abdomen.

2. Although the fetal echocardiogram does not require the patient to have a full bladder, if combined with an obstetric ultrasound, the mother is then required to have a full bladder. The patient is asked to drink five to six glasses of fluid (water or juice) about 1–2 hours before the examination. If she is unable to do so, intravenous fluids may be administered. She is asked to refrain from voiding until the examination is complete. Tell the patient that she will have a strong urge to void during the examination. Discomfort caused by pressure applied over a full bladder may be experienced. If the bladder is not sufficiently filled, three to four 8-oz glasses of water should be ingested, with rescanning done 30–45 minutes later.

3. See Chapter 1 guidelines for intratest care.

Abnormalities detected during fetal echocardiography include:

1. Cardiac arrhythmias

2. Septal defects, including tetralogy of Fallot

3. Hypoplastic heart syndrome

4. Valvular abnormalities, including Ebstein anomaly (abnormality of the tricuspid valve)

5. Cardiac tumors

6. Vessel abnormalities, including coarctation of aorta, transposition, aortic stenosis, truncus arteriosus, and pulmonary stenosis

Pretest Patient Care

1. Provide a brief explanation of the procedure to be performed, emphasizing that it is not uncomfortable or painful and is not harmful to the mother or fetus. Explain that the procedure can be repeated without harm. Benefits of the procedure should also be explained.

2. Explain that a liberal coating of coupling agent must be applied to the skin so that there is no air between the skin and the transducer and to allow for easy movement of the transducer over the skin and that a sensation of warmth or wetness may be felt. The couplant (ultrasound gel) does not stain or discolor clothing, but the patient may prefer to don a gown.

3. The sonographer may explain the images on the screen in basic terms. A photograph or video recording may be provided (per institution policy).

4. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

1. Artifacts may be produced when the transducer is moved out of contact with the skin. This can be resolved by adding more coupling agent to the skin and repeating the scan.

2. Artifacts (reverberations) may be produced by echoes emanating from the same surface several times. This can be avoided by careful positioning of the transducer.

3. A posterior placental site may be difficult to identify because of the angulation of the reflecting surface or insufficient penetration of the sound beam owing to the patient’s size.

Normal

• Normal structure of heart and great vessels

• Normal heart rate and rhythm, with proper hemodynamic flow through heart and great valves