Is it necessary to have an amniocentesis for high-risk pregnant women during the Down syndrome screening?

Patient's question:

I am 15 weeks pregnant. Today, I received the results of the Down syndrome screening test. The risk of trisomy 21 biochemical markers is 1:902, the risk of neural tube defects is 1:4744, and the risk of trisomy 18.

Doctor's answer:

Analysis of the condition: Based on your results from the triple screen test, there is only an age-related risk, while other tests are low-risk.
Guidance: This result indicates a low risk, so amniocentesis is not necessary. You can consider undergoing a 4D ultrasound instead.