A pregnancy ultrasound is an imaging test that uses sound waves to create a picture of how a baby is developing in the womb. It is also used to check the female pelvic organs during pregnancy.
Pregnancy sonogram; Obstetric ultrasonography; Obstetric sonogram; Ultrasound - pregnancy; IUGR - ultrasound; Intrauterine growth - ultrasound; Polyhydramnios - ultrasound; Oligohydramnios - ultrasound; Placenta previa - ultrasound; Multiple pregnancy - ultrasound; Vaginal bleeding during pregnancy - ultrasound; Fetal monitoring - ultrasound
How the Test is Performed
To have the procedure:
In some cases, a pregnancy ultrasound may be done by placing the probe into the vagina. This is more likely in early pregnancy, Many women will have the length of their cervix measured by vaginal ultrasonography around 20 to 24 weeks of pregnancy.
How to Prepare for the Test
You will need to have a full bladder to get the best ultrasound image. You may be asked to drink 2 to 3 glasses of liquid an hour before the test. DO NOT urinate before the procedure.
How the Test will Feel
There may be some discomfort from pressure on the full bladder. The conducting gel may feel slightly cold and wet. You will not feel the ultrasound waves.
Why the Test is Performed
An ultrasound may be done to determine if there is a problem with the pregnancy, how far along the pregnancy is, or to take measurements and screen for potential problems.
Talk to your health care provider to determine the most appropriate scanning schedule for you.
A pregnancy ultrasound may be done during the first 12 weeks of pregnancy to:
A pregnancy ultrasound may also be done in the second and third trimesters to:
Some centers are now performing a pregnancy ultrasound called a nuchal translucency screening test around 9 to 13 weeks of pregnancy. This test is done to look for signs of Down syndrome or other problems in the developing baby. This test is often combined with blood tests to improve the accuracy of results.
How many ultrasounds you will need depends on whether a previous scan or blood test has detected problems that require follow-up testing.
The developing baby, placenta, amniotic fluid, and surrounding structures appear normal for the gestational age.
Note: Normal results may vary slightly. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal ultrasound results may be due to some of the following conditions:
Current ultrasound techniques appear to be safe. Ultrasound does not involve radiation.
Richards DS. Obstetric ultrasound: imaging, dating, growth, and anomaly. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 9.
Wapner RJ, Dugoff L. Prenatal diagnosis of congenital disorders. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 32.
Wolf RB. Abdominal imaging. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 26.
Review Date: 1/30/2020
Reviewed By: LaQuita Martinez, MD, Department of Obstetrics and Gynecology, Emory Johns Creek Hospital, Alpharetta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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