Medical Ultrasonography is a medical diagnostic technique used to visualize inner body structures like muscles and other soft tissues as well as organs like the liver, gallbladder and various other structures. It helps to identify any pathology in the tissues and record any lesion.
The Ultrasound Machine
The word ‘ultrasound’ refers to sound waves with a frequency too high for human ears to hear. In medical ultrasound, sound waves in frequencies ranging from 1.6 to 10 megahertz are employed. Superficial structures like muscles, tendons, thyroid etc are at a higher frequency (7–18 MHz) while deeper structures such as the liver and kidney are imaged at a lower frequency 1–6 MHz.
Ultrasonography utilizes sound waves which are sent into the body in pulsatile waves with the help of a transducer or probe. The sound waves bounce off the structures and the echo is received by the probe and displayed on screen on a monitor.
Ultrasonography used during pregnancy to monitor the growth and health of the fetus and other pregnancy tissues like the placenta and amniotic fluid is known as Obstetrical ultrasound and is widely used. Nowadays, it is a routine procedure performed in all pregnancies in the first trimester to help identify any anatomical defects in the fetus.
Ultrasonography is also used as an aid in treatment procedures – for example, draining of fluid or pus or in ultrasound guided biopsies. This procedure is known as interventional ultrasonography.
Other types of ultrasonography include cardiac ultrasonography (echocardiography), dental ultrasonography, Doppler ultrasonography to study blood flow and muscle motion as well as high intensity focused ultrasonography. Lithotripsy , a procedure used to break up kidney stones is a type of high intensity focused ultrasonography.
Compared to other medical devices, ultrasound has many advantages – it is safe because it does not use any ionizing radiation, the device is portable and can be easily carried to the patient’s bedside, it is not very expensive and the results are obtained in real time, meaning that the result is available instantly at the time of the test and the patient does not need to wait for a long time for the report to be available.
The main disadvantage of ultrasound is that it requires a skilled operator for an accurate report. Another disadvantage is that structures behind bones may not be readily seen.
Ultrasonography is one of the most widely used diagnostic aids in medical care today.