Best Way to Take Tests and Procedures in Pregnancy Second Trimester

You usually have your first ultrasound in the second trimester. (Some physicians choose to do a sonogram in the first trimester.) Midwives may not include a sonogram in their prenatal care. You may request one.

There are two ways to have an ultrasound. The more common is with an abdominal transducer. With this method, you must drink several large glasses of water before getting on the examining table, and you refrain from using the bathroom until the procedure is com­plete, since a full bladder helps get a better picture of the uterus. Once on the examining table, a warm liquid gel is put on your abdomen. A wand or sticklike device called a transducer is rolled across the gel and sends sound waves into the abdomen. The transducer transmits a picture of your organs or the baby to a TV screen. Ultrasound does not hurt, but it can be a bit uncomfortable because of the fullness of your bladder.

Another way to do an ultrasound is to use a vaginal transducer. This method is helpful for early diagnosis of suspected problems, such as an abnormal placement of the placenta. It also can determine if the length of the cervix might cause difficulties in pregnancy. For an ultrasound with a vaginal transducer, you also will lie on your back on an examining table, but your legs will be in stirrups, as if for a vaginal exam. The vaginal transducer is similar to the size and shape of a tampon. It feels like a speculum used during a pap smear.

Either kind of ultrasound helps yourOBprovider measure the length of the fetus and confirm how far along you are in your preg­nancy. Sometimes after seeing and measuring the baby with ultra­sound, yourOBprovider may change the date your baby is due by a few days. If you’re unsure when your last menstrual period started, an ultrasound can help the doctor/midwife determine when the baby is likely to be born. The ultrasound may also help confirm whether you’re carrying more than one baby.

Another recommended test is the maternal serum alpha-fetoprotein (MSAFP), also called a Triple screen, which identifies women who should consider further testing for genetic disorders in their babies. A blood sample for MSAFP is usually drawn at a prenatal appointment in the beginning of the second trimester. If results of the MSAFP indicate potential problems, a genetic test, amniocentesis, can be scheduled for the twentieth week of pregnancy. For amniocentesis, a small sample of amniotic fluid is withdrawn and evaluated using ultrasound. Another option for women who need this information earlier is chorionic villus sampling, which can be done as early as 10 weeks. It is usually offered to women who have had a previous child with genetic disorders.