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What are choroid plexus cysts and how are they detected in the fetus


When performing the second trimester ultrasound, the doctor can inform the mother that her baby has a choroid plexus cyst in the brain, which immediately generates great anguish in the parents, so, below, we are going to highlight the most important aspects of this ultrasound finding.

The choroid plexuses are structures of the brain located in the cerebral ventricles (IV ventricle, III ventricle and lateral ventricles). They begin their development in the embryonic period and are composed of highly vascularized epithelial tissue.

Its main function is the production of cerebrospinal fluid, which is an essential element for the protection of the central nervous system (brain and spinal cord). In addition, they act as a filtration system, removing metabolic waste, foreign substances, and excess neurotransmitters in the cerebrospinal fluid.

The choroid plexus cysts they constitute a small accumulation of fluid within the choroid plexuses, mainly those located in the lateral ventricles and can be visualized when performing the second trimester ultrasound (between week 18 and 22 of pregnancy).

Most of the time they are an incidental finding, they can be visualized in low-risk pregnancies, with a frequency of 1-2% of pregnant women, they are unilateral or bilateral and the size and number of cysts can vary although they generally do not measure more 10 mm.

They can occur in equal proportions between male and female fetuses, they do not interfere with normal brain development nor do they cause brain damage and in most cases they disappear at 26-28 weeks of pregnancy, so they generally do not represent a danger for the baby.

The choroid plexus cysts they are not a tumor or a type of cancer, but the doctor must make a differential diagnosis with other cystic pathologies such as arachnoid cysts, cystic tumors, midline cysts associated with agenesis of the corpus callosum and arteriovenous malformations in the fetal brain.

The importance of visualizing and identifying choroid plexus cysts it is due to its possible association with aneuploidies. Between 1% and 2% are associated with chromosomal alterations, mainly with trisomy 18 and, to a lesser extent, with trisomy 21 or prenatal infections (although different population studies have not supported this association), the only significant association with trisomy 18 .

This chromosomopathy presents structural alterations and fetal growth easily identifiable by ultrasound at present. Choroid plexus cysts may be seen in 30% to 50% of fetuses with this trisomy. In these cases, cysts tend to be large, bilateral, so a complete and thorough study of the fetus should be performed by specialized medical personnel to search for malformations or ultrasound markers secondary to these two chromosomal diseases and even carry out invasive genetic studies for prenatal diagnosis (amniocentesis).

Another possibility would be to find a choroid plexus cyst on screening ultrasound between weeks 11 and 13 + 6 with ultrasound or biochemical markers that increase the risk for trisomy 18, which would be an indication for invasive genetic studies or non-invasive studies in maternal blood , depending on the availability of them in each healthcare center.

Exceptionally, if the cyst persists and is located near the Monroe foramen (which communicates the lateral ventricles with the III ventricle), it can cause ventriculomegaly and the management of these babies at birth will be jointly with the pediatric neurologist.

If no other structural alterations or malformations are found when performing the second trimester ultrasound, you can calm down and you should wait for the next ultrasound control to evaluate and control the cyst. Generally disappear in 90% of cases And if your doctor observes that it has disappeared around 26-28 weeks of pregnancy, the baby will develop normally without any repercussions in the future.

In some cases, the visualization of these cysts may persist when performing the ultrasound controls of the third trimester of pregnancy, without presenting variations in their diameter and generally unilateral, and in these cases your doctor will surely indicate a cerebral transfontanelar ultrasound to the newborn (visualize the brain structures of the baby by placing the transducer in the fontanelles).

Clinically, the majority of newborns who persist with small Choroid plexus cysts are asymptomatic and do not require treatment, and even such cysts, can be part of incidental ultrasound findings in case a brain ultrasound is performed on a newborn for any other cause; Therefore, these newborns do not present alterations in motor function, development and cognitive abilities and behavior will be normal.

As we have seen, the formation of choroid plexus cysts is related to the histological development of the plexuses, so physicians must be very careful in interpreting small choroid plexus cysts as abnormal and we must be very cautious in the way in which We present the information to our patients so as not to cause unnecessary distress and anxiety.

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Video: 20 Weeks Pregnant. Bilateral Choroid Plexus Cyst (September 2020).