Obstetric sonogram
Key points
- Pregnancy ultrasound is a method of imaging the fetus and the female pelvic organs during pregnancy.
- A clear, water-based conducting gel is applied to the skin over the area being examined to help with the transmission of the sound waves.
- Since a full bladder is necessary for improved imaging, you may be asked to drink 2 to 3 glasses of liquid 1 hour before the test.
- There may be some discomfort from pressure on the full bladder.
Alternative names
Pregnancy sonogram; Obstetric ultrasonography; Pregnancy ultrasound; Ultrasound - pregnancy
Definition
Pregnancy ultrasound is a method of imaging the fetus and the female pelvic organs during pregnancy. The ultrasound machine sends out high-frequency sound waves which bounce off body structures to create a picture.
How the test is performed
You will be lying down for the procedure. A clear, water-based conducting gel is applied to the skin over the area being examined to help with the transmission of the sound waves. The ultrasound transducer (a hand-held probe) is then moved over the abdomen and pelvis. This is the conventional transabdominal technique.
How to prepare for the test
Since a full bladder is necessary for improved imaging, you may be asked to drink 2 to 3 glasses of liquid 1 hour before the test. You should not urinate before the examination.
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
There is no definitive rule as to the number of scans a woman should have during her pregnancy. Some physicians will order an ultrasound when an abnormality is suspected on clinical grounds, while others advocate screening ultrasounds. You should consult your health care provider to determine the most appropriate scanning schedule for you.
Scans may be performed in the first trimester to:
- Confirm a normal intra-uterine pregnancy
- Assess fetal age
- Exclude abnormalities such as ectopic pregnancies or potential for miscarriage
- Assess fetal heart activity
- Determine the presence of multiple pregnancies
- Identify abnormalities of the placenta, uterus, and other pelvic structures
Scans may also be obtained in the second and third trimesters to:
- Assess fetal age, growth, position and sometimes gender
- Identify congenital malformations
- Exclude multiple pregnancies
- Evaluate the placenta, amniotic fluid, and remaining structures of the pelvis
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.