|Other names: Ultrasound scan is also called a sonogram.
What Is An Ultrasound?
It is a test doctors perform to see inside the body. Ultrasounds use sound waves rather than radiation (X-rays and CT scans use radiation) to create images of organs in the body. Those images are reflected on a nearby video monitor.
An ultrasound can be used in several ways:
1. To monitor an unborn baby. In pregnancy they are used to check on the progress of the fetus, to confirm a due date, detect the presence of a multiple birth or birth defect.
2. To diagnose a condition. They are used to:
• Detect heart problems, an echocardiogram is an ultrasound of the heart.
• Detect gynecological conditions like ovarian cysts, PCOS, uterine fibroids and pelvic pain.
• To guide certain gynecological treatments such as endometrial ablation.
• Locate a wandering IUD device.
• Detect an ectopic pregnancy (pregnancy outside of the womb).
• Detect the cause of infertility and monitor the effectiveness of fertility treatments like ovarian stimulation and embryo transfer as part of IVF treatment.
• Detect various cancers including thyroid, kidneys, pancreas and breast cancer. It helps to differentiate between benign (noncancerous) tumors and cancer tumors.
3. To guide surgeons performing certain types of biopsy: Such as amniocentesis, chorionic villi sampling and breast biopsy for detecting breast cancer.
Are There Different Types Of Ultrasound?
Yes, there are 3 different types of ultrasound, these are:
• External Ultrasound
• Internal Ultrasound
• Endoscopic Ultrasound
An external ultrasound is one where nothing is inserted into the body. It is used to diagnose many conditions from heart disease to ovarian cysts and uterine fibroids. The procedure is the same as for pregnancy scans. A small handheld device called a transducer is rubbed over the the area to be scanned (be that the tummy, neck, breasts or throat for example). A jelly-like lubricating gel is smeared on the skin which allows the transducer to move smoothly and ensures continuous contact between the skin and the sensor. Black and white images are reflected on a nearby video monitor.
If the area to be scanned is the tummy, then the scan may also be referred to as a pelvic scan, transabdominal scan or abdominal scan.
The most common example of a transabdominal scan is a pregnancy ultrasound scan. It is the same procedure as above. A small handheld device called a transducer is rubbed over the tummy. A jelly-like lubricating gel is smeared on the skin and black and white images are reflected on a video monitor. There are several different types of scans performed on pregnant women, they are given different names according to what week in pregnancy they are performed and for what purpose. These include:
3D image and 4D video ultrasound. Some fetal imaging centers specialize in producing 4D videos or 3D 'portraits’ of fetuses (see pictures). Using ultrasound technology, these 'keepsake' images show facial features, fingers, toes, movement and the gender of the baby (if requested).
Nuchal scan (12 week scan).
Anatomy scan (extensive scan done between weeks 18 and 22)
Third trimester ultrasound scan (weeks 28 to 40).
How accurate is a scan at predicting gender?
Can endometriosis be diagnosed by ultrasound?
When the ultrasound probe is inserted into the vagina, it is sometimes called a transvaginal scan or a vaginal scan.
An internal ultrasound is where a probe is placed inside the vagina or rectum and images are transmitted to a monitor. This is a newer type of ultrasound and is used to look closely at the reproductive organs such as the womb and ovaries. A rectal examination provides information about rectal cancer and polyps (as well as the prostate gland in men). A transvaginal ultrasound is where the probe is inserted into the vagina. It can help detect endometrial cancer and ovarian cancer, as well as many other minor conditions. Internal examinations can be a little uncomfortable but they do not usually hurt.
An endoscopic ultrasound combines endoscopy with ultrasound. In this procedure a long thin tube called an endoscope is inserted into the body through the mouth to examine your stomach, esophagus, gall bladder or the lymph nodes in your chest. It has a light and ultrasound device at the end which emits images back to a monitor. It is quite uncomfortable so you will be given a sedative to keep you calm. Internal and endoscopic ultrasounds can provide more detailed images of certain organs of the body.
How Do I Prepare For A Scan?
If you are having a pregnancy scan you may be asked to drink lots of water and to hold it in before your scan. A full bladder helps push up the womb so the baby is easier to see. But for other scans you may be told not to eat or drink for 6 hours before the scan.
Are There Any Risks?
To date there are no known risks to patients or unborn babies from ultrasound technology. There is some risk of internal tears and bleeding from endoscopic ultrasound.
How Do Ultrasounds Work? The Techie Bit
To create an image by ultrasound the ultrasound probe sends pulses of ultra high frequency sounds into the body. The probe acts as listening device, waiting for the sounds it emitted to bounce off the tissue it encounters and echo back. The time taken to echo back depends on the density of the body material it meets. Different densities have different predictable echo times. Sound travels fast through liquid, less fast through soft tissue like fat and muscle and slowly through air. Hard bone does not transmit sound at all, but reflects straight back leaving a dark shadow. This is why ultrasound is no good for detecting broken bones. A CT scan, X-ray or MRI scan are more suitable. Once the probe picks up the echoes coming back to it, the software in the ultrasound machine analyzes the data and gives a pixel on the monitor a shade of gray corresponding to the tissue depth and density. This is updated multiple times a second so that the image you see on the monitor appears live in real-time.