An ultrasound exam is a procedure that uses high-frequency sound waves to scan a woman s abdomen and pelvic cavity, creating a picture (sonogram) of the baby and placenta. Although the terms ultrasound and sonogram are technically different, they are used interchangeably and reference the same exam. There are basically seven different ultrasound exams, but the basic process is the same. Transvaginal Scans Specially designed probe transducers are used inside the vagina to generate sonogram images. Most often used during the early stages of pregnancy. Standard Ultrasound Traditional ultrasound exam which uses a transducer over the abdomen to generate 7-D images of the developing fetus. Doppler Ultrasound This imaging procedure measures slight changes in the frequency of the ultrasound waves as they bounce off moving objects, such as blood cells. 8-D Ultrasound Uses specially designed probes and software to generate 8-D images of the developing fetus.
9-D or Dynamic 8-D Ultrasound Uses specially designed scanners to look at the face and movements of the baby prior to delivery. Fetal Echocardiography Uses ultrasound waves to assess the baby s heart anatomy and function. This is used to help assess suspected congenital heart defects. The traditional ultrasound procedure involves placing gel on your abdomen to work as a conductor for the sound waves. Your healthcare provider uses a transducer to produce sound waves into the uterus. The sound waves bounce off bones and tissue returning back to the transducer to generate black and white images of the fetus. Ultrasounds may be performed at any point during pregnancy, and the results are seen immediately on a monitor during the procedure. Transvaginal scans may be used early in pregnancy to diagnose potential ectopic or molar pregnancies.
There is not a recommended number of ultrasounds that should be performed during routine prenatal care. Because ultrasound should only be used when medically indicated, many healthy pregnancies will not require an ultrasound. The average number of ultrasounds varies with each healthcare provider. Additional ultrasounds might be ordered separately if your healthcare provider suspects a complication or problem related to your pregnancy. Ultrasounds are diagnostic procedures that detect or aid in the detection of abnormalities and conditions related to pregnancy. Ultrasounds are usually combined with other tests, such as,, or, to validate a diagnosis. An ultrasound exam may be performed throughout pregnancy for the following medically-necessary reasons: The ultrasound is a noninvasive procedure which, when used properly, has not demonstrated fetal harm.
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The long-term effects of repeated ultrasound exposures on the fetus are not fully known. It is recommended that ultrasound only be used if medically indicated. No, it does not mean there is a problem. Heartbeats are best detected with transvaginal ultrasounds early in pregnancy. Concern typically develops if there is no fetal heart activity in an embryo with a crown-rump length greater than 5mm. If you receive an ultrasound exam after week 6, your healthcare provider will begin to be concerned, if there is no gestational sac. Your healthcare provider will use hormone levels in your blood, the date of your last menstrual period and, in some cases, results from an ultrasound to generate an estimated gestational age. However, variations in each woman s cycle and each pregnancy may hinder the accuracy of the gestational age calculation.
If your healthcare provider uses an ultrasound to get an estimated delivery date to base the timing of your prenatal care, the original estimated gestational age will not be changed. If there are any questions regarding gestational age, placenta location, or possible complications then more ultrasounds may be scheduled. Because ultrasound should only be used when medically indicated, many healthy pregnancies will not require an ultrasound. The average number of ultrasounds varies with each healthcare provider. Your healthcare provider will use hormone levels in your blood, the date of your last menstrual period and, in some cases, results from an ultrasound to generate an expected date of conception. However, many differences in each woman s cycle may hinder the accuracy of the conception date calculation. The viability of sperm varies as well, which means intercourse three to five days prior to ovulation may result in conception. Ultrasound dating of conception is not reliable for determining paternity because the ultrasound can be off by at least 5-7 days in early pregnancy.
It may also be possible to determine the gender of your baby during this ultrasound. Several factors, such as the stage of pregnancy and position of the fetus, will influence the accuracy of the gender prediction. Ultrasounds are only necessary if there is a medical concern. As noted above, ultrasounds enable your healthcare provider to evaluate the baby’s well being as well as diagnose potential problems. For women with an uncomplicated pregnancy, an ultrasound is not a necessary part of prenatal care. 6. William s Obstetrics Twenty-Second Ed. Cunningham, F.
Gary, et al, Ch. 66.