Choroidal cysts are seen on ultrasound in some pregnancies in the second trimester, but most of them disappear on their own by 24 weeks. Some studies have reported a slightly higher chance of chromosomal abnormalities (especially trisomy 18) in fetuses with such cysts, but most of these fetuses with chromosomal abnormalities will have other major abnormalities in addition to the cysts. If there are other abnormalities, amniocentesis should be done to rule out chromosomal abnormalities. 2. It is recommended to wait until 26-28 weeks of pregnancy to do a 4D ultrasound review, the image is clear and three-dimensional, which can provide a better reference. The choroid plexus cyst definition: choroid plexus cyst is a small, scattered, ≥3mm diameter cyst found on ultrasound in the lateral ventricle of the developing fetus at 14-24 weeks gestational age. 90% of fetal choroid plexus cysts disappear after 26 weeks gestation, and only a few show progressive increase. The detection of choroid plexus cysts should be combined with other clinical data for further amniocentesis amniotic fluid culture or umbilical cord puncture for umbilical cord blood culture to exclude chromosomal abnormalities such as trisomy 18 and trisomy 21. Choroid plexus cysts can also appear in normal fetuses, but most of them resolve after 26 weeks. If they do not resolve after 26 weeks and are bilateral, a cranial examination and chromosomal examination of the umbilical cord blood cells should be done after the birth of the child. If it disappears, there will be no signs of pressure or increased cranial pressure, and the intelligence or other aspects of the child’s life will not be affected by the “bilateral choroid plexus cysts” after birth. Ultrasound diagnosis 1. Cystic dark areas are seen within the strong echogenicity of the choroid plexus, with thin walls and smooth, neat edges, mostly round. The cyst can be single or multiple.2. Dynamic observation of the size of the cyst, if the cyst is less than 1CM or getting smaller, chromosomal abnormalities are less likely, and attention should be paid to check whether new malformations appear in other parts, sometimes after ultrasound detects the choroid plexus cyst, other malformations cannot be detected. However, some scholars believe that the risk of chromosomal abnormalities in the fetus does not change with the size and number of choroid plexus cysts, whether they are bilateral or unilateral, and whether they are progressively shrinking or disappearing, and that when choroid plexus cysts are detected, further amniocentesis with amniotic fluid cells or umbilical cord puncture blood culture should be performed in conjunction with other clinical data to exclude chromosomal abnormalities such as trisomy 18 and trisomy 21. Prognosis: Simple choroid plexus cysts often have no clear pathological significance and have a good prognosis. However, fetal choroid plexus cysts are associated with an increased risk of chromosomal abnormalities (trisomy 18, trisomy 21, etc.). Ma Xiangtao, Department of Pediatrics, Anyang Third People’s Hospital