Ultrasound - Seeing with Sound

from the book How to Have a Baby: Overcoming Infertility
by Dr. Aniruddha Malpani, MD and Dr. Anjali Malpani, MD .

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Ultrasound or sonography has helped revolutionize our approach to the infertile patient. Ultrasound machines are the newest addition to the gynecologist’s bag of tricks; and help him to "image" or see structures in the female pelvis. Ultrasound uses high frequency sound waves much like SONAR machines used in ships for detecting submarines underwater. The high frequency sound waves are bounced off the pelvic organs; and the reflected sound waves are received by the probe ( transducer) and a computer is used to reconstruct the waves into black and white images on the monitor. Ultrasound machines today are all real-time machines, which give dynamic images.

In the old days, ultrasound for infertility was done through the abdomen. This required you to fill up your bladder ( till it was ready to burst !) so that the sound waves could be transmitted into the pelvis. However, the standard ultrasound technique today for infertility is vaginal ultrasound ( endovaginal scanning) in which a long, slim, slender probe is inserted into the vagina and used for imaging the pelvic organs. Not only is this much more comfortable for you; it also gives much sharper and clearer pictures, since the probe is much closer to the pelvic structures.

What can you see on ultrasound? The ultrasound gives clear pictures of the uterus; and the ovaries. It allows the doctor to look for fibroids; ovarian cysts; and ectopic pregnancies. It is also excellent for early diagnosis of pregnancies. However, the ultrasound scan is not very good for assessing whether or not the tubes are normal.

Ovulation scans allow the doctor to determine accurately when the egg matures; and when you ovulate. This is often the basic procedure for most infertility treatment since the treatment revolves around the wife's ovulation. Daily scans are done to visualize the growing follicle, which looks like a black bubble on the screen. Most women can see the follicle clearly for themselves - and know by the scans when the egg has ruptured. Other useful information which can be determined by these scans is the thickness of the uterine lining - the endometrium. The ripening follicle produces increasing quantities of estrogen, which cause the endometrium to thicken. The doctor can get a good idea of how much estrogen you are producing (and thus the quality of the egg) based on the thickness and brightness of the endometrium on the ultrasound scan.

Fig 1. Ultrasound scan showing multiple follicles
 

Fig 2. 
Ultrasound scan of the uterus, showing a normal endometrium, which appears as a triple band in the center of the uterus

One of the commonest findings on an ultrasound scan is an ovarian cyst. A cyst is a collection of fluid surrounded by a thin wall (a fluid-filled sac) that develops in the ovary. Typically, ovarian cysts are functional (not disease-related) and disappear on their own. During ovulation, a follicle may grow , but fail to rupture and release an egg. Instead of being reabsorbed, the fluid within the follicle persists and forms a follicular cyst. The other type of functional cyst is a corpus luteum cyst, which develops when the corpus luteum fills with blood. Functional ovarian cysts usually resolve on their own, and are not to be confused with other pathological conditions involving cystic ovaries, specifically polycystic ovarian disease, endometriotic cysts, or ovarian tumours. Since an ultrasound picture is just a black and white shadow, the doctor has to be skillful in interpreting what the image means. Simple cysts are thin walled, and appear as a large black bubble. Cysts which contain blood ( for example, chocolate cysts found in patients with endometriosis) will have echoes within them, which appear white, and these are described as complex masses on ultrasound. The incidence of follicular cysts is increased in infertile patients taking drugs (such as clomiphene and HMG) for ovulation induction. Functional ovarian cysts usually disappear within 60 days without treatment. However, if the cyst is larger than 6 cm, or persists for longer than 6 weeks, then further testing may be needed.

Who does the scans? Ultrasound scans can be done either by a radiologist; or by the gynecologist or infertility specialist himself. Remember that the eye only sees what the mind knows, so you must go to a good clinic for your scans. The benefit of having the scans done by the infertility specialist himself is that he can make immediate decisions regarding your treatment based on the scan findings. If the radiologist does the scans, then you have to wait till your doctor has seen the report before knowing what to do next since the radiologist does not make the treatment decisions. In any case, it is vital that the ultrasound scans be done in the Infertility Clinic itself, so that your waiting can be minimized - and you don't have to run around from the sonographer to the gynecologist. If there are any abnormal findings, it is vital that your gynecologist see the actual ultrasound for himself during the scan. This provides much more information than the printed pictures.

Recent Advances in Ultrasound

Ultrasound technology has made dramatic advances in recent years, and now tests have been described which allow the doctor to use ultrasound to assess tubal patency. Basically, these involve passing a fluid into your tubes through the uterus; and the gynecologist can see the passage of the bubbles into the tubes and out into the abdomen. Since this test (sonosalpingography) can be done in the doctor's clinic itself, and does not involve X-ray radiation, it has advantages - especially for documenting that the tubes are normal. However, the gold standard for tubal testing remains HSG and laparoscopy today.

Doppler: The newer ultrasound machines have Doppler attachments which allow the doctor to judge the flow of blood in the blood vessels. The most exciting advance is that of Colour Doppler, where the blood flow can be mapped in color on the monitor. While still a research tool, it may provide important information for assessing the infertile patient in the coming years.

Three – dimensional ultrasound. Using sophisticated microprocessors, the newest ultrasound machines allow the doctor to reconstruct the image, so that he gets a three dimensional view. While this provides excellent pictures, the true value of this technique for infertility still has to be evaluated.

Ultrasound now also offers infertile patients newer treatment options not available before. Modern surgical techniques have progressively become less and less invasive - all to the patient's benefit! From laparotomy to laparoscopy, and now to ultrasound guided procedures, we are witnessing a change in the gynecologist's armamentarium from the knife to the endoscope to the guided needle !

The benefits to the patient are many and include : reduced costs; reduced hospitalisation ; reduced risk of complications; and better preservation of fertility, with increased chance of conception for the future.

Ultrasound-guided procedures can be used to treat a variety of problems seen in the infertile woman.

1. Egg pickup for IVF - The use of vaginal ultrasound for egg pickup has made egg retrieval a short, simple and inexpensive procedure, which can be performed in a day-care unit, under sedation and local anesthesia . The ovaries are normally present in the pouch of Douglas, and are very accessible transvaginally. Moreover, the presence of adhesions does not interfere with egg collection.
    
2. Ovarian cyst aspiration. An ovarian cyst is a very common condition in which fluid collects in the ovary. However, cysts which are more than 5 cm in size need to be treated, as they can cause problems (e.g., twisting and rupture). Normally, surgery had to be done to remove these cysts - and often this damaged the surrounding normal ovary as well. With ultrasound-guidance, we can stick a needle from the vagina into the cyst, and empty the contents ( usually clear fluid ) by sucking it out. This empties the cyst, which often does not recur.
    
3. Treatment of ectopic pregnancy . With technological advances (ultrasound and beta-HCG blood tests) the diagnosis of tubal pregnancy can be made very early, usually before rupture. It can be treated by injecting a toxic chemical, methotrexate, into the sac, which causes the tissue to die and then get reabsorbed, without any surgery whatsoever. In more advanced tubal pregnancies, potassium chloride can be injected direct into the heart of the baby in the ectopic gestational sac, thus killing it and preventing it from growing.
    
4. Ultrasound-guided tubal embryo and gamete transfer for IVF and GIFT techniques. Techniques have been devised to pass a special tube - the Jansen-Anderson catheter set - into the fallopian tubes through the vagina under ultrasound guidance, so as to place the embryos and /or the gametes in the fallopian tube. Since the tube offers a better environment for the gametes and embryos than the uterine cavity, it is believed that this will improve pregnancy rates.
    
5. Tubal recanalisation for cornual blocks (proximal tubal obstruction) . Often cornual blocks are due to the presence of mucus plugs and amorphous debris in the tubal lumen. Ultrasound guided tubal catheterization can effectively treat the blocked tubes in some of these patients.

The scope of ultrasound guided procedures has increased dramatically in the last few years; and with further improvements in technology, we can expect this list to become even longer, and doctors become more versatile with using this technology.

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