In which trimester can an ultrasound first be used to examine the fetus for brain and spine defects?

The first trimester is the period during which an ultrasound can first be utilized to examine the fetus for brain and spine defects, particularly through a specialized ultrasound technique called first-trimester nuchal translucency screening. This screening, typically performed between 11 and 14 weeks of gestation, allows for early detection of certain congenital anomalies, including neural tube defects (NTDs).

During this early stage of pregnancy, although the fetal structures are still developing, the ultrasound can provide crucial information regarding the formation of the brain and spine. This early examination can lead to timely intervention and management if any abnormalities are detected.

While subsequent trimesters also allow for further and more detailed imaging of fetal anatomy, the correct identification of potential issues in the first trimester offers an opportunity for early diagnosis and informed decisions regarding maternal-fetal care. In the second and third trimesters, more comprehensive assessments can be made, but the initial detection can begin as early as the first trimester.