Britannica
Sources used in this answer
How can ultrasound help guide a needle during amniotic-fluid testing or a biopsy?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
ultrasonics
Learn how collapsing bubbles with sound can create sonoluminescence.
Ultrasound assists in guiding medical procedures like needle biopsies and the collection of amniotic fluid by providing real-time, nonionizing imaging of internal structures.
The process relies on the following principles:
- Piezoelectric Transducers: These devices generate pulses of high-frequency ultrasound that are directed into the body.1
- Acoustic Impedance: As the waves travel through the body, they encounter changes in acoustic impedance at the borders between different tissues or organs, causing the waves to reflect back as echoes.21
- Visualization: An electronic apparatus analyzes these echoes to determine the position of the tissues. This data is displayed as a two-dimensional plot, allowing a physician to visualize the target area and the needle simultaneously.21
By providing this visual feedback, ultrasound allows practitioners to navigate the needle precisely, ensuring that the procedure is performed safely while avoiding damage to the fetus or surrounding healthy tissue. Because ultrasound is nonionizing, it is a preferred, safe method for these sensitive diagnostic procedures.12