Information & Outcomes
How are anomalies classified?
There are many ways anomalies can be classified, and each term merits an explanation of its own.
First, they can be categorized by how they occur.
Anomalies can be genetic, environmental, or a combination of the two.
Second, anomalies can be categorized by where they occur. Meaning, fetal anomalies of the central nervous system, cardiovascular system, or gastrointestinal system to name three. Anomalies categorized by organ system can help to explain related treatment plans by system.
Third, anomalies can be grouped by severity: this is where you will hear the terms “major” or “minor”, and this often attempts to explain, at a high level, the medical, cosmetic and social implications of the abnormality.
Fourth, anomalies can be categorized by how the problem developed. These four categories are: malformations, deformations, disruptions, and dysplasia.
In our written content, we provide you with a handout breaking down each of these terms in more detail.
In summary, anomalies can come about through several factors, and can affect one or many organ systems.
Major fetal anomalies that are treatable usually require medical treatment, such as in-utero procedures, medications for the fetus or surgery right after birth.
Minor fetal anomalies may require no treatment at all.
Now, for those that want to hear more about the terms and categories we just described, we’ll go into more detail to follow.
Genetic anomalies by definition are linked to a specific genetic cause.
Some chromosome changes are numerical (too few or too many, which doctors describe as aneuploidy). Trisomy 21, (Down syndrome), Trisomy 18, Trisomy 13, and sex chromosome abnormalities are some of the most common aneuploidies we see in the US today.
Other chromosome changes are smaller in nature, like chromosome structural rearrangements or gene mutations. Common mutations include cystic fibrosis, sickle cell disease, and color blindness.
Environmental anomalies are linked to exposures such as infection, physical harm, medication exposure, a lack of an essential nutrient, or a toxin like alcohol.
Sometimes, the combination of genetic susceptibility AND environment lead to malformations, as in the case of a diet lacking adequate folic acid and a family history of neural tube defects.
Knowing both genetic AND environmental risks allows parents to decrease the risk of fetal anomalies. Two ways parents can take initiative in these areas are:
Preconceptual genetic counseling
Prioritizing environmental health
Preconceptional genetic counseling regarding known family history can help ensure a safe environment for a future pregnancy.
Environmental health can be optimized through proven management, including taking a multivitamin and adequate folic acid, maintaining weight, avoiding smoking, alcohol and drugs, and other healthy lifestyle choices.
Structural anomalies by definition arise when organ structures are forming, during early pregnancy. I will break down the four categories, which are: malformations, deformations, disruptions, and dysplasia.
MALFORMATIONS are defects of organs or body parts due to an intrinsically abnormal development process. A structure can be not formed, partially formed, or formed in an abnormal fashion. Malformations most often occur between the 3rd-8th weeks of pregnancy, though there are some organs that continue to develop over the course of the pregnancy. An example of a malformation is anencephaly, an anomaly of the brain where the skull does not form.
DEFORMATIONS result when initially normal fetal structures are modified by intrauterine forces, such as decreased amniotic fluid or uterine abnormalities (even crowding in multiple gestations), leading to pressure on the fetus. An example of a deformation is clubfoot or congenital hip dislocation, where the hip joint is not properly aligned.
DISRUPTION is a vascular or mechanical process that leads to tissue compromise, such as compression, strangulation, hemorrhage, thrombosis, or any process that interferes with fetal blood flow. An example of a disruption is amniotic band syndrome, where strands of the amniotic sac adhere to and entangle parts of the fetus.
DYSPLASIA happens when cells are disorganized when they are becoming tissues, An example of dysplasia is skeletal dysplasia, where the abnormal growth of bone cells cause presentations like shortened limbs.
“Major” malformations have significant health implications for baby, often requiring surgery, and can be fatal. The good news is, some of these have treatment options and incredible fetal therapy improvements are being made every day.
“Minor” malformations have mostly cosmetic significance. They rarely are medically significant or require surgical intervention.
We have now described in more detail the big terms used to classify fetal anomalies.
Every known anomaly can be supported by thorough resources in and of itself. Our team is here to provide that for you, along with accredited fetal surgery centers across the US.