Ultrasound: what it is, when and why it is done
Ultrasound scanning: a fetus of a few millimetres in its mother’s womb, the hip of a newborn baby, the shoulder of a young athlete, the liver of an adult, the bladder of an elderly person… all seemingly unrelated things
Today, however, there is a long, thin thread linking organs and functions of the body that begins even before the first wail: the possibility of ‘seeing’ many of our vital structures thanks to ultrasound.
The ultrasound is sent by a very popular diagnostic tool: the ultrasound scanner
This is connected to a probe which, moved and oriented by the hands of the operating doctor, captures the returning ultrasound and sends it back to the ultrasound scanner, where the signals are decoded and transformed into images.
The signals are then decoded and transformed into images, giving a precise definition, a real map, of the part being studied.
Ultrasound waves penetrate tissue without harming it because they are not X-rays.
They do not therefore impose any form of protection on the individual, who can therefore repeat the examination several times.
The very use of ultrasound during pregnancy, i.e. at a stage when the body in function of the foetus could be affected by any external element capable of interfering with its development, says a lot about the harmlessness of the test.
Ultrasonography can be used to study numerous organs (including the thyroid, breast, muscles, liver and biliary tract, pancreas, spleen, kidney, prostate, bladder, uterus and ovaries) and to determine structural changes in these organs as a result of various diseases.
In particular, ultrasound can reveal nodules of various kinds, provided they reach an appreciable size (5 – 10 mm).
It is possible to carry out different types of ultrasound:
– Ultrasound of the neck: study of the thyroid gland, parathyroid glands and lymph nodes in the neck.
– Mammary ultrasound: study of the mammary gland in young women (up to 35 years of age) or for diagnostic completion after mammography.
– Abdominal ultrasound: study of the liver, bile ducts, gallbladder, pancreas, spleen, kidneys, abdominal aorta, bladder.
– Transrectal ultrasound: study of the prostate and seminal vesicles.
– Testicular ultrasound: study of the didyme and epididymis, venous plexus (varicocele evaluation).
– Gynaecological ultrasound: study of the uterus and ovaries.
– Ultrasound of muscles and tendons: study of the joints (shoulder, elbow, wrist, knee, ankle; hip only in babies up to 3 months old), muscles and tendons.
– Ultrasound examination of the skin and subcutis: examination of changes (nodules, swellings, etc.) in the skin and dermis and superficial lymph nodes (neck, armpits, groin, etc.).
– Ultrasound of the newborn’s hip: study of the newborn’s hip up to 3 months of age.
– Vascular ultrasound: study of veins and arteries.
– Obstetric ultrasound: study of the fetus.
– Interventional ultrasound: ultrasound guidance for histological and cytological sampling manoeuvres and therapeutic manoeuvres.
Ultrasound: what are the limitations of this examination?
The examination does not allow all parts of the body to be assessed, because the ultrasound cannot pass through its various physical structures without distinction.
The examination is therefore useless when assessing organs surrounded by bone or air, because the ultrasound cannot pass through them and is therefore reflected.
What needs to be done before ultrasound?
For the study of the abdominal organs (in particular the liver and gallbladder) it is good practice to follow a diet low in waste (no fruit and vegetables, cheese and fizzy drinks) for 3 days before the examination and to fast for at least 5 hours before the examination (water and medicines can be taken freely).
For the study of pelvic organs (bladder, uterus and ovaries, prostate), a full bladder is required (having finished drinking about 1 litre of water 1 hour before the examination).
In certain conditions (study of abdominal and pelvic organs in patients suffering from constipation and in transrectal e. for the study of the prostate) it is advisable to have a cleansing enema the evening before the examination.
For all other examinations, no preparation is necessary.
How is the ultrasound examination carried out?
The examination is neither painful nor uncomfortable.
The doctor spreads a gel on the skin surface over the tract to be explored and moves the ultrasound probe over it; the examination lasts 10 – 20 minutes, during which the patient must avoid movement and must, at certain times and at the request of the examiner (only for the examination of the upper abdomen) hold his/her breath.
The examination may be accompanied by moderate discomfort only during special procedures (insertion of the probe into the rectum in the transrectal examination, into the vagina in the transvaginal examination).
What should be done after the examination?
After the examination, the patient does not need to perform any special regimens or prescriptions and can immediately resume normal activity.
If necessary, the doctor may recommend repeating the examination after carrying out more thorough preparation, if this has not been sufficient.