About First Trimester Ultrasounds

According to the American Pregnancy Association, ultrasounds are diagnostic procedures that aid in the detection of various abnormalities related to different stages of pregnancy. First trimester ultrasounds can help confirm a viable pregnancy, date the gestational age of the fetus and diagnose ectopic or molar pregnancies. Ultrasounds are noninvasive procedures that have not demonstrated harm to the mother or fetus, but they are only used when medically necessary to detect or confirm a suspected problem. Most insurance companies now cover one or more first trimester ultrasounds when there is medical cause for the procedure to be performed.

Function

First trimester ultrasounds are used to identify early developmental abnormalities in the pregnancy, such as ectopic pregnancy and threatened miscarriage, and provide an accurate method of dating the pregnancy and fetus.

Types

There are two types of first trimester ultrasounds: transvaginal scanning, which offers the greatest detail and is the preferred type of scan during the first month, and abdominal scanning, which enables a wider field of view.

Time Frame

Ultrasound scans during the first trimester may detect the gestational sac as early as 4 weeks, the yolk sac during the 5th week of the pregnancy, the fetal pole after the 6th week and can date the pregnancy and measure the fetus based on the size of the crown rump length between 6 and 12 weeks gestation.

Benefits

First trimester ultrasounds are able to detect missed abortions, threatened abortions, ectopic pregnancies and other developmental abnormalities or complications that may require immediate medical attention to preserve the life of the fetus and/or mother.

Considerations

First trimester ultrasounds are not 100 percent accurate at detecting pregnancy, and very early pregnancies may be missed due to an inexperienced practitioner, poor capabilities of the specific equipment used, the orientation of the uterus or the type of ultrasound performed.

Resources

• American Pregnancy Association