What are the different kinds of soft markers, and how often are they seen?

[Anonymous]

What are the different kinds of soft markers, and how often are they seen?

[Genetic Counselor]

Doctors group findings under the term “soft marker” when they are seen on a routine or detailed anatomy ultrasound, usually performed in the middle of pregnancy, and are not attached to any other structural problem. The most commonly identified soft markers are:

• Echogenic intracardiac focus A small bright spot within one of the heart’s pumping chambers, caused by a tiny area of calcium buildup on the muscle fibers that anchor the heart valves. It has no effect on how the heart works and is seen in a meaningful minority of all pregnancies.
• Choroid plexus cysts Small, fluid-filled pockets within the choroid plexus, a structure inside the brain that produces the fluid surrounding the brain and spinal cord. These cysts form when folds of tissue trap fluid during normal brain development and are found in roughly one to three percent of all pregnancies.
• Echogenic bowel A portion of the baby’s intestine that appears unusually bright on ultrasound, sometimes as bright as bone. This can be a normal variant, though it has a wider range of possible explanations than most other soft markers, discussed further below.
• Urinary tract dilation (mild renal pelviectasis) A small amount of extra fluid within the collecting system of one or both kidneys, usually mild and often resolving on its own before or shortly after birth.
• Shortened humerus or femur An arm bone or thigh bone measuring somewhat shorter than the average expected for the baby’s gestational age, based on standard growth curves.
• Thickened nuchal fold A slightly increased thickness of the skin fold at the back of the baby’s neck, measured at the same mid-pregnancy scan.
• Absent or underdeveloped nasal bone The bridge of the nose appearing smaller than expected, or not clearly visible, on ultrasound.
• Single umbilical artery An umbilical cord with two blood vessels instead of the usual three, one artery and one vein rather than two arteries and one vein.

Each of these findings has its own separate, and often quite different, level of association with chromosome conditions, which is why your care team’s counseling should always be specific to the exact marker found rather than treating “soft marker” as one uniform category.

[Author]

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