Abdominal Ultrasound Imaging

An abdominal ultrasound image is a useful way of examining internal organs, including the liver, gallbladder, spleen, pancreas, kidneys, and bladder. Because US images are captured in real time, they can show movement of internal tissues and organs and enable physicians to see blood flow. This can help to diagnose a variety of conditions and to assess damage caused by illness.

Ultrasound imaging is used extensively for evaluating the kidneys, liver, gallbladder, pancreas, spleen, and blood vessels of the abdomen. Because it provides real-time images, it can also be used to:

• Guide procedures such as needle biopsies, in which needles are used to sample cells from organs for laboratory testing.
• Help a physician determine the source of many abdominal pains, such as stones in the gall bladder or kidney, or an inflamed appendix.
• Help identify the cause for enlargement of an abdominal organ.

Doppler ultrasound is a special type of ultrasound study that examines major blood vessels. These images can help the physician to see and evaluate:

• Blockages to blood flow, such as clots.
• Build-up of plaque inside the vessel.
• Congenital malformation.
• With knowledge about the speed and volume of blood flow gained from an ultrasound image, the physician can often determine whether a patient is a good candidate for a procedure like angioplasty.

The patient is positioned on an examination table, and a clear gel is applied to the abdomen to help the transducer make secure contact with the skin. The sound waves produced by the transducer cannot penetrate air, so the gel helps to eliminate air pockets between the transducer and the skin. The sonographer or radiologist then presses the transducer firmly against the skin and sweeps it back and forth to image the area of interest.

When the examination is complete, the patient may be asked to dress and wait while the ultrasound images are reviewed, either on film or on a monitor. Often, though, the sonographer or radiologist is able to review the ultrasound images in real time as there may be varying degrees of discomfort from pressure as the radiologist or sonographer guides the transducer over your abdomen, especially if you are required to have a full bladder. The examination usually takes less than 30 minutes.

Pelvic Ultrasound Imaging

Pelvic ultrasound is most often used to examine the uterus and ovaries and, during pregnancy, to monitor the health and development of the embryo or fetus. In men, a pelvic ultrasound usually focuses on the bladder and the prostate gland.

Millions of expectant parents have seen the first "picture" of their unborn child thanks to pelvic ultrasound examinations of the uterus and fetus (see the Ultrasound-Obstetric page). However, monitoring of fetal development is not the only reason for a pelvic ultrasound exam.

For women, ultrasound examinations can help determine the causes of pelvic pain, abnormal bleeding, or other menstrual problems. Ultrasound images can also help to identify palpable masses such as ovarian cysts and uterine fibroids, as well as ovarian or uterine cancers. Sonohysterography (saline infusion sonography) is a relatively new procedure in which sterile saline is injected into the uterus while a transvaginal sonogram is performed. The purpose is to distend the uterine cavity (endometrial cavity) to look for polyps, fibroids, or cancer, especially in patients with abnormal uterine bleeding. Other indications include evaluation of the uterine cavity looking for uterine anomalies (abnormal uterine shapes since birth) or scars. The saline outlines the lesion and allows for easy visualization and measurement. Some physicians also use sonohysterography for patients with infertility. Saline and air are injected into the uterus and the physician looks for air bubbles passing through the fallopian tubes, which would indicate patency of the fallopian tubes.

In men, pelvic ultrasound is a valuable tool for evaluating the prostate gland, as well as for evaluating the seminal vesicles.

A pelvic ultrasound exam can help to identify stones, tumors and other disorders in the urinary bladder in both men and women. Because ultrasound provides real time images, it can also be used to guide procedures, such as needle biopsies, in which a needle is used to sample cells from an abnormal area for laboratory testing. Doppler sonography is another method of ultrasound that can be used to evaluate blood flow in pelvic vessels.

There are three methods of performing pelvic ultrasound: abdominal (transabdominal), vaginal (transvaginal, endovaginal) in women, and rectal (transrectal) in men. The same principles of high-frequency sound apply in each technique.

For the transabdominal approach, the patient has a full urinary bladder and is positioned on an examination table. A clear gel is applied to the lower abdomen to help the transducer make secure contact with the skin. The sound waves produced by the transducer cannot penetrate air, so the gel helps to eliminate air pockets between the transducer and the skin. The sonographer then presses the transducer firmly against the skin and sweeps it back and forth to image the pelvic organs. Doppler sonography can be performed through the same transducer.

Transvaginal ultrasound involves the insertion of the transducer into the vagina after the patient empties her bladder and is performed very much like a gynecologic exam. The tip of the transducer is smaller than the standard speculum used when performing a Pap test. A protective cover is placed over the transducer, lubricated with a small amount of gel, and then inserted into the vagina. Only two to three inches of the transducer end are inserted into the vagina. The images are obtained from different orientations to get the best views of the uterus and ovaries. Doppler sonography can be performed through the transvaginal transducer, which is the same transducer used during sonohysterography. Transvaginal ultrasound is usually performed with the patient lying on her back and with her feet in stirrups as during a gynecologic exam.

The prostate gland is located directly in front of the rectum, so the ultrasound exam is performed transrectally. A protective cover is placed over the transducer, lubricated, and then placed into the rectum so the sound need only travel a short distance. The images are obtained from different orientations to get the best view of the prostate gland. Ultrasound of the prostate is most often performed with the patient lying with his left side down on the table and with his knees bent up slightly toward the chest.

If a suspicious lesion is identified with ultrasound or with a rectal examination, an ultrasound-guided biopsy can be performed. This procedure involves advancing a needle into the prostate gland while the radiologist watches the needle placement with ultrasound. A small amount of tissue is taken for microscopic examination.

Each method has its advantages. The transabdominal approach offers an expanded view of the entire pelvis, showing where one internal structure is in relation to another. Since the transducer is brought closer to the area being examined in the transvaginal and transrectal approaches, improved visualization may be achieved. Thus, it can be helpful in locating the embryonic heartbeat in an early pregnancy, evaluating the uterine texture, or measuring a cyst in an ovary. Your physician or radiologist will decide whether one or a combination of approaches is best for your particular case.

When the examination is complete, the patient may be asked to dress and wait while the ultrasound images are reviewed, either on film or on a monitor. Often, though, the sonographer or radiologist is able to review the ultrasound images in real time as they are acquired, and the patient can be released immediately.

Ultrasound imaging of the pelvis should be painless. With transabdominal ultrasound, you will lie on your back on an examining table. The radiologist or sonographer will spread some gel on your skin and then press the transducer firmly against your body, moving it until the desired images are captured. There may be varying degrees of discomfort from pressure as the transducer is moved over your abdomen, especially if you are required to have a full bladder.

With transvaginal ultrasound, although the examination is often performed to look for a cause of pelvic pain, the sonogram itself should not be painful or significantly increase your discomfort. A vaginal sonogram is usually more comfortable than a manual gynecologic examination.

If no biopsy is required, transrectal ultrasound examination of the prostate is similar in discomfort to a rectal exam performed by your doctor. If a biopsy is performed, additional discomfort, due to the needle insertion, is usually minimal because the rectal wall is relatively insensitive in the region of the prostate.

Almost all examinations take less than 30 minutes.

Obstetric Ultrasound Imaging

Obstetric ultrasound refers to the specialized use of sound waves to visualize and thus determine the condition of a pregnant woman and her embryo or fetus.

Obstetric ultrasound should be performed only when clinically indicated. Some indications may be:

• To establish the presence of a living embryo/fetus.
• To estimate the age of the pregnancy.
• To diagnose congenital abnormalities.
• To evaluate the position of the fetus.
• To evaluate the position of the placenta.
• To determine if there are multiple pregnancies.

You will be asked to lie on your back or side. You will also be asked to expose your lower abdominal area. The sonographer or radiologist then spreads a warm water-soluble gel over your lower abdomen. This gel allows better transmission of the sound waves by making it easier to move the transducer over your abdomen and by sending the sound beam directly into the body without the interference from even a tiny amount of air on the skin. The transducer emits high-frequency sound waves as the sonographer or radiologist moves it over your abdomen. The transducer also detects the echoes that bounce off anatomic structures as reflections. Sometimes the radiologist determines that a transvaginal scan will need to be performed. Instead of a transducer being moved over your abdomen, the high-frequency waves will be emitted by a transducer placed in the vagina. This technique often provides improved, more detailed images of the uterus and ovaries. It is especially useful in early pregnancy. With this approach the urinary bladder needs to be empty. Shown is an example of a transvaginal transducer. Only two to three inches of the transducer are inserted into the vagina. The rest of the transducer is a handle for use by the operator.

The obstetric ultrasound examination takes about 20 minutes.

This is a painless procedure. There may be varying degrees of discomfort from pressure as the sonographer or radiologist guides the transducer over your abdomen, especially if you are required to have a full bladder. At times the sonographer may have to press more firmly to get closer to the embryo or fetus to better visualize the structure. This discomfort is temporary. Also, you may dislike the feeling of the water-soluble gel applied to your abdomen. With transvaginal scanning, there may be minimal discomfort as the transducer is moved in the vagina.

Carotid and Abdominal Aorta Ultrasound Imaging

Ultrasound of the carotid arterial system provides a fast, noninvasive means of identifying blockages of blood flow in the neck arteries to the brain that might produce a stroke or mini-stroke. Ultrasound of the abdominal aorta is primarily used to evaluate for an aneurysm which is an abnormal enlargement of the aorta usually from atherosclerotic disease.

The patient is positioned on an examination table that can tilt and move. A clear gel is applied to the area that will be examined. The gel helps the transducer make a secure contact and eliminates air pockets between the transducer and the skin, since the sound waves cannot penetrate air. The sonographer, vascular technologist, or radiologist then presses the transducer firmly against the skin and sweeps along the area of interest, reviewing the images on the monitor and capturing "snapshots" as required.

When the examination is complete, the patient may be asked to dress and wait while the ultrasound images are reviewed, either on film or on a monitor. Often, though, the sonographer or radiologist is able to review the ultrasound images in real time as they are acquired, and the patient can be released immediately.

Most ultrasound studies are fast and easy. You will lie on your back on an examining table that may be tilted or moved to provide access to the area that will be imaged. The sonographer or radiologist will spread some gel on your skin and then press the transducer firmly against your body, moving it until the desired images are captured. Most exams take less than 30 minutes; however, more complicated examinations may take somewhat longer.

Venous Ultrasound Imaging

The most common reason for a venous ultrasound exam is to search for blood clots, especially in the veins of the leg. These clots may break off and pass into the lungs, where they can cause a dangerous condition called pulmonary embolism. If found in time, there are treatments that can prevent this from happening.

Other reasons to do a venous ultrasound study:

Find the cause of long-standing leg swelling. In people with varicose veins, a common condition, the valves that keep blood flowing in the right direction may not work well, and venous ultrasound can help the surgeon decide how best to deal with this condition.

Aid placement of a needle or catheter in a large interior vein. Sonography can help locate the exact site of the vein and avoid complications such as bleeding or air in the chest cavity.

Map out the veins in the leg or arm so that segments may be removed and used to bypass an area of disease. An example is using pieces of vein from the leg to surgically bypass narrowed coronary arteries.

Examine a blood vessel graft used for dialysis if it is not working as expected; an area of narrowing in the graft may be responsible.

After positioning the patient on the adjustable examination table, the technologist will apply a gel-like material onto the skin to make close contact between the skin and transducer, eliminating air pockets. This will ensure that the sound waves are freely conducted into and out of the body. The radiologist or technologist presses the transducer firmly to the skin and moves it back and forth to obtain complete images of areas of interest. The entire area of interest will be scanned, obtaining images from different perspectives. Sometimes the examiner may want to obtain images while you are standing upright. You will be asked to relax and remain calm during the examination. The radiologist also may ask you health-related questions during the exam and may repeat some images to clarify the findings.

You will not hear any of the ultrasound emission or the echoes sent back to the screen, although you may hear pulse-like sounds if a Doppler examination is ordered. You probably will lie on your back, and the table may be tilted or moved to provide better access to a particular area. You may be standing for the procedure. Often you will have a chance to watch the screen along with the examiner, though it will not be easy to make sense out of what you see. Most ultrasound studies take no longer than a half-hour. Venous ultrasound is usually a painless examination. If, however, your leg is swollen and tender, the pressure from the ultrasound transducer may add to your discomfort.