Is there any difference between the “major anomaly scan” and 4D ultrasound?

Pregnant women require regular prenatal examinations throughout pregnancy—particularly during the first and second trimesters. To prevent congenital fetal anomalies, screening for structural abnormalities typically begins around week 12 of gestation. The most common procedures performed for this purpose are the “comprehensive anomaly scan” (often referred to as the “major anomaly scan”) and four-dimensional (4D) ultrasound.

Is there a difference between the comprehensive anomaly scan and 4D ultrasound?

4D ultrasound is currently one of the most advanced tools available for detecting fetal structural abnormalities. It provides clearer, more detailed, and three-dimensionally rendered real-time images of the fetus within the uterus, enabling clinicians to assess whether congenital anomalies are present—such as cleft lip and/or palate, asymmetrical eye size, or abnormalities in the nervous, urinary, or digestive systems. However, 4D ultrasound is generally recommended between weeks 24 and 28 of gestation.

The comprehensive anomaly scan is also a method used to screen for fetal structural abnormalities; however, it encompasses a broader range of diagnostic assessments. For instance, this scan typically begins at week 12 of gestation and includes multiple components: nuchal translucency (NT) measurement, screening for Down syndrome (trisomy 21), and—often—4D ultrasound imaging. Thus, the comprehensive anomaly scan and 4D ultrasound share significant overlap.

Regardless of whether undergoing the comprehensive anomaly scan or 4D ultrasound, it is strongly recommended that examinations be conducted at accredited, reputable medical institutions. Moreover, successful 4D ultrasound imaging depends partly on fetal cooperation. If the fetus is positioned with its back toward the transducer, the pregnant woman may be advised to perform gentle physical activity to encourage fetal movement—ideally prompting the fetus to turn its face toward the ultrasound probe—thereby facilitating optimal image acquisition. Importantly, 4D ultrasound must be performed within the recommended gestational window.

The above outlines key distinctions—and similarities—between the comprehensive anomaly scan and 4D ultrasound. We hope this information proves helpful.