Ultrasound

• Ultrasound is a prenatal screening test that uses high-frequency sound waves to create images of the fetus and its surroundings.



• Ultrasound can assess fetal growth, development, anatomy, position, movement, heart rate, and placental location
• Ultrasound can also estimate gestational age, due date, fetal weight, and amniotic fluid volume
• Ultrasound can detect fetal anomalies such as neural tube defects, cardiac defects, cleft lip/palate, skeletal dysplasia, .
• Ultrasound can also detect multiple gestations, placenta previa, placental abruption, ectopic pregnancy, .
• Ultrasound can be performed at any time during pregnancy but is usually done at specific intervals depending on the purpose and indication
• Ultrasound can be done by two methods: transabdominal or transvaginal
• Transabdominal ultrasound involves placing a transducer coated with gel on the pregnant person’s abdomen and moving it to obtain images of the fetus and its surroundings
• Transvaginal ultrasound involves inserting a transducer covered with a condom and gel into the pregnant person’s vagina and obtaining images of the fetus and its surroundings
• Ultrasound has no known risks or complications for the pregnant person or the fetus

Preparation and Procedure of Prenatal Ultrasound

• • The patient should have a full bladder for a transabdominal US and an empty bladder for a transvaginal US.
  • The patient should wear loose-fitting clothing and lie supine on an examination table.
  • A gel is applied to the abdomen or the vaginal probe to facilitate sound transmission.
  • The sonographer moves the transducer over the abdomen or inserts it into the vagina to obtain images of the fetus and the placenta.
  • The images are displayed on a monitor and recorded for interpretation by a radiologist or an obstetrician.
  • The procedure usually takes 15 to 30 minutes, depending on the type and purpose of the US.

Different types of Prenatal Ultrasounds

1. Dating Ultrasound: Typically performed between 8 and 12 weeks of gestation. It is used to estimate the due date, confirm the number of fetuses, and assess early pregnancy development.
2. Nuchal Translucency (NT) Ultrasound: Conducted between 11 and 14 weeks of gestation. It measures the thickness of the fluid-filled space at the back of the baby's neck to screen for chromosomal abnormalities, such as Down syndrome.
3. Anatomy Ultrasound (Anomaly scan): Usually performed between 18 and 22 weeks of gestation. It provides a detailed examination of the baby's organs, limbs, and overall anatomy, helping to detect any structural abnormalities.
4. Growth Ultrasound: This ultrasound may be performed at various intervals throughout the pregnancy, depending on individual circumstances. It assesses the baby's growth, including measurements of the head, abdomen, and femur length, and compares them to standardized growth charts.
5. Doppler Ultrasound: It can be performed at different gestational ages as needed. Doppler ultrasound measures blood flow in the umbilical cord, placenta, and fetal vessels to evaluate the baby's circulation and oxygenation.
6. Third-Trimester Biophysical Profile (BPP): Typically conducted during the third trimester, usually after 28 weeks of gestation. The BPP combines ultrasound with a non-stress test to evaluate the baby's well-being by assessing various parameters, such as fetal movement, breathing, muscle tone, amniotic fluid volume, and heart rate patterns.