Frequently Asked Questions
1. Is ultrasound safe?
Ultrasound is high frequency sound waves which are beyond human capacity for hearing. Current ultrasound technology works by transmitting this sound wave through the body and detecting echoes returning from different tissue densities. There is no ionizing radiation involved as in x-ray. Current understanding suggests that ultrasound poses no detectable risk to either fetus or mother. However, that is not to say that future studies will not discover new risks. Moreover, a developing fetus is inherently more fragile and more susceptible to external forces and should be treated with more care. Consequently, in ultrasound we follow the ALARA principle (As Low As Reasonably Achievable) - using the minimum power level and time needed to complete each ultrasound scan.
2. What can I expect to see on ultrasound?
At 6 weeks gestation, you should be able to identify fetal heart tone on vaginal ultrasound. Also twins, triplets, and multiple order gestation can be easily seen. At 20 weeks, fetal development is matured enough for identification of most major organs including the genitalia. Also important at this stage is an estimate of fetal size and placental location. At 30 weeks gestation, the fetus should have enough adipose tissues for good evaluation of facial features using 3D ultrasonography.
Please note that sometimes due to the baby's size, gestational age, position, and maternal body habitus we will not be able to perform an adequate exam. Sometimes when the legs are crossed for example, we will not be able to determine the baby's sex. Most of the times we will ask patients to return another day when hopefully fetal position will have changed and organ development will have further matured.
3. What is the difference between 2D, 3D, and 4D ultrasounds?
2D or rather realtime 2D ultrasound is currently the standard for ultrasonographic screening and diagnosis of fetal anomalies. It has the capability of taking cross sectional views of internal organs making it useful for evaluating internal structural abnormalities. The real-time or "moving picture" component help increase the resolution of the images. 3D add the capability to view the external surfaces of the fetus. There are a few conditions, like cleft lips and certain spinal cord defects, which are easier to demonstrate by 3D than by 2D. The differences in these two modalities are analogous to the differences between x-rays versus photographic pictures. One is designed to view the internal structures and the other to view the external surfaces. 4D ultrasound adds the moving component to the 3D (the fourth dimension being time) similarly to taking a video versus a still picture. Other than a nice view of the fetus in motion, 4D has limited diagnostic values.
4. What anomaly can ultrasound detect?
Like all medical diagnostic tests, ultrasound is a tool used to detect a specific set of abnormal conditions; it will not detect anything out side of that set of conditions. Conditions currently detectable to a varying degree by ultrasound includes anencephaly, hydrocephaly, neurotube defect (e.g. spina bifida), cleft palate, cleft lip, cardiovascular malformation (e.g. heart defect), diagphagmatic hernia, omphalocele, gastroschesis, renal malformation, limb abnormality, growth restriction, macrosomia, cervical incompetence, placenta previa, oligohydramnios, down syndrome, trisomy 13, trisomy 18, etc. This list is by no means exhaustive, but it does demonstrate the extensive set of conditions that we must look for specifically during each ultrasound. Unfortunately, the list of diseases not detected by us (e.g. sickle cell disease, muscular dystrophy, mental retardation, cerebral palsy) is exponentially longer. Color doppler contribute to the evaluation of in utero fetal distress.
Detectable gynecologic condition includes structural uterine, fallopian tube, and ovarian pathology such as fibroid, hydrosalpinx, ovarian cyst, and ovarian cancer. Color doppler is helpful here for distinguish between benign and malignant adnexal lesion. A relatively new technique in ultrasound is sonohysterography which involves injection of saline into the uterine cavity to detect endometrial polyp and endometrial cancer.
5. When is a best time to perform an ultrasound?
On each pregnancy, we like to perform three ultrasounds. The first ultrasound is performed endovaginally at 11- 14 weeks looking at fetal number, age, and nuchal translucency (a marker for Down syndrome). The second (abdominal 2D) ultrasound is performed at 20-22 weeks looking for central nervous system, cardiac, abdominal wall, urinary system abnormalities as well as placental placement, umbilical vessels, and cord insertions. This is also a good time for measurements of fetal biparietal diameter, head circumference, abdominal circumference and femur length to ascertain appropriate fetal growth. If the baby is cooperating, we should be able to glimpse at the sex at this time. We like to perform the 3D ultrasound at 28-30 weeks as this is the best time to obtain images of the face looking for clefts, and of limbs looking at toes and fingers. We will also perform a 2D scan at this time to confirm appropriate growth, check placental placement and adequacy of amniotic fluid. Additional ultrasound scans are performed throughout pregnancy with appropriate medical indication.
We prefer to perform the gynecologic ultrasound at cycle day 5-10; but, most gynecologic exam can be performed anytime. Exceptions include sonohysterography which should be performed after bleeding has stopped, and follicular scan for infertility which is very cycle day specific.
6. Can a normal ultrasound guarantee a normal baby?
Again, ultrasound will not detect all abnormal conditions. It will detect only structural abnormalities large enough to be seen. Smaller lesions will be missed. Moreover, medical condition changes with time; and if the condition has not developed sufficiently at the time of the exam it will not be detected. Hydrocephaly for example may develop late in pregnancy and will be missed at the time of the second trimester ultrasound. With all the hype and the cute baby pictures, it is easy to loose site of the limitations of the ultrasound.
Obviously, the tool can only be as good as its operator. You will not get the same result from an untrained technician as from a well trained physician, for example. Indeed, a recent study (the RADIUS Trial) found that ultrasound in the community setting was dismal at detecting fetal anomalies - with all of 17 cardiac anomalies missed. Even in a tertiary center, of the 22 cardiac anomalies present, only 4 was detected by ultrasound. To help reduce this limitation, we believe that all ultrasounds should be directly supervised or performed by a well trained physician with sufficient clinical experience.
7. Can a normal gynecologic ultrasound guarantee that I do not have cancer?
This is like taking pictures of a woman's skin and then asking if she has skin cancer. If the pictures are detailed enough we maybe able to say she probably does not have the cancer. How sure we are of that probability depends on how clear and thorough our pictures are. We will be wrong if the cancer is too small to be detected by our pictures. We will also be wrong if the cancer develops in the future.
Ultrasounds of the female organs have the same limitations. It is a set of pictures taken at a finite point in time. If the pathology is too small to be detected or has yet to develop, it will be missed. Ovarian cancer for example, can only be detected by ultrasound if it has caused the ovary to become significantly larger than normal. Early ovarian cancer not yet exerting a mass effect will be missed.
The converse of this is that a lot of lesions detected by ultrasound are not pathology at all. We are constantly referred patients who are worried about ovarian cysts detected by ultrasounds at the community offices. The vast majority of these are normal. Unfortunately, the technicians performing these scans are not trained to distinguish the differences. Or if they are, they are not allowed to talk to the patient about diagnosis due to medico-legal concerns. This is one of the reasons why we think it is important for obstetricians and gynecologists be trained to perform and interpret their own ultrasound.
Back to the analogy, the more pictures you take of a person's skin over time, the more lesions you will see. The question now is which lesion should you worry about and which one is considered normal. Would it not be simpler if the person taking the pictures is trained to interpret and treat skin cancer, as opposed to having the physician sends the patient to the photographer who then send the photographs to some one else to read?
8. What do I have to do to prepare for the ultrasound?
Unlike CT scan or colonoscopy, there is relatively little preparation. You do not have to fast; you do not have to have bowel prep. You may or may not have to come with a full bladder depending on the study scheduled. But, please make sure you are well hydrated the days before you come. You will be instructed at the time you schedule your appointment. We do recommend that you wear loose comfortable clothing.
9. How long does the ultrasound take?
Approximately 15 to 45 minutes depending on the exam. The 3D ultrasound without the real-time 2D diagnostic exam takes about 20 minutes.
10. What can I expect during the ultrasound?
Any new experience can potentially be anxiety provoking. We like to make the experience as pleasant as possible. There is no pain involved. You should be about 15 minutes early to your appointment for paper work. You will have a brief consultation period with the physician performing the scan where your remaining questions can be answered. You will then be lead to a comfortable darkened room for the ultrasound. Most exams are abdominal and can be performed in your street clothes. We recommend you wear loose comfortable clothing which can easily expose your abdomen. Some non-staining pre-warmed gel will be spread on your abdomen. Lie back and enjoy the view of the window into your womb.
If you need an endovaginal scan (usually for gynecologic and first trimester exam) you will be asked to change into a hospital gown. A small probe covered with warm gel will be inserted into your vagina. It is smaller and much less uncomfortable than the speculum of your annual pelvic exam.
You can resume normal activity immediately after the exam.
11. Can I have my family with me?
Absolutely! Fetal ultrasound is a unique experience in modern medicine. It is an ideal time to nurture family bonding. We encourage you to bring your love ones to share this experience. Please be aware of our room limitation, however. Any more than two to three visitors become overly crowded. We will send you home with pictures and a video to share with the rest of your family and friends.
12. How much does it cost?
From $120 to $500 depending on the procedure.
Click here to see our cash price schedule.
13. Does my insurance cover the cost?
Most insurance will cover one or two 2D ultrasounds during your pregnancy depending on your plan. Additional 2D ultrasound and 3D/4D ultrasound are not covered. Even with appropriate medical indication, many insurance companies will make you pay out of pocket.
Gynecologic 2D exams are usually covered with appropriate indication. The 3D exam for gynecology is still investigational and will not be covered.
14. I am seeing someone else for my prenatal care; can I still get my ultrasound from the Sugarland Women's Health Center?
We do recognize that this technology is not yet widely available in the Sugar Land area. So as a service to the rest of the community, we will offer it to you either with or without your physician's referral. However, if you are self referred, please do not ask us to deal with your insurance company. We much rather spend the time taking care of our patients.
