What dimension of ultrasound is the "major anomaly scan"?

Feb 28, 2023 Source: Cainiu Health

Dr. Lv Aiming

Introduction

In general, the detailed anomaly scan can be performed using two-dimensional, three-dimensional, or four-dimensional ultrasound. The full name of this scan is "mid-trimester fetal ultrasound screening for major anomalies," which refers to an ultrasound examination conducted during the middle stage of pregnancy. The optimal time for mid-trimester anomaly screening is between 18 and 24 weeks of gestation, as this period is best suited for evaluating fetal anatomy and detecting structural abnormalities.

Generally, the detailed anomaly scan can be performed using two-dimensional (2D) ultrasound, three-dimensional (3D) ultrasound, or four-dimensional (4D) ultrasound. The specifics are as follows:

1. Two-Dimensional Ultrasound

The detailed anomaly scan is a general term for a comprehensive and systematic fetal examination. It helps detect potential fetal structural abnormalities such as cleft lip and palate, short fingers, visceral malformations, polydactyly, and ear deformities. Using 2D ultrasound for the anomaly scan allows visualization of fetal anatomy across various planes to identify any abnormalities.

2. Three-Dimensional Ultrasound

Three-dimensional ultrasound provides a stereoscopic image. It creates a 3D reconstruction by combining multiple 2D images. Performing the anomaly scan with 3D ultrasound enables visualization of the fetus’s three-dimensional structure and dynamic changes, making the findings more vivid and easier to interpret.

3. Four-Dimensional Ultrasound

Four-dimensional ultrasound adds the dimension of time to 3D ultrasound imaging, allowing real-time observation. Using 4D ultrasound for the anomaly scan provides a more intuitive assessment of fetal development and enhances the detection of fetal abnormalities.

The full name of the "detailed anomaly scan" is mid-trimester fetal ultrasound screening for major congenital anomalies, which refers to an ultrasound examination performed during the second trimester of pregnancy. The optimal time for this screening is between 18 and 24 weeks of gestation. This period is ideal for evaluating fetal anatomical structures and detecting congenital abnormalities, helping to identify chromosomal abnormalities, single-gene disorders, congenital malformations, and certain genetic syndromes.

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Is the major anomaly scan classified as level two or level three?

Major anomaly screening generally falls under Level 3 prenatal screening. It primarily refers to a four-dimensional color ultrasound examination performed between 22 and 28 weeks of pregnancy to determine whether fetal abnormalities are present. This examination allows for a clear assessment of whether the fetus's limbs, body, and internal organs show any abnormalities. During the 4D ultrasound, the movements of the fetus within the uterine cavity can be directly observed on an electronic screen.

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Can a detailed anomaly scan detect toxoplasmosis infection?

In general, major anomaly screening cannot detect toxoplasmosis infection. Major anomaly screening refers to a series of examinations and screening methods used to comprehensively evaluate the physical condition and structural development of the fetus, in order to identify potential congenital abnormalities and malformations. These examinations include ultrasound scans, blood tests, and other imaging studies, aiming to detect and assess fetal developmental abnormalities as early as possible.

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Does the major anomaly scan include an examination of the reproductive system?

Anomaly scan is a routine prenatal screening examination primarily used to assess fetal development and rule out potential congenital abnormalities. The anomaly scan is usually performed between the 18th and 20th weeks of pregnancy, using ultrasound imaging to observe the fetus's organs and structures. During the anomaly scan, the doctor thoroughly examines various fetal organs and systems, including the reproductive system.

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Which is better: 4D ultrasound or major anomaly scan?

4D ultrasound and anomaly scan (detailed structural scan) each have their strengths in fetal examination: 4D ultrasound is better for assessing the fetal heart, while the anomaly scan is superior for detecting overall fetal developmental abnormalities. 4D ultrasound is primarily used to check for congenital heart defects, aiding in the diagnosis of conditions such as fetal rheumatic heart disease and tetralogy of Fallot. It provides a clearer, three-dimensional visualization of the fetal heart's thickness, shape, and size.