Pregnancy Ultrasound

Once a positive pregnancy test is obtained (either from urine or through a positive beta-hCG blood test), the ultrasound monitoring of the pregnancy begins.

Pregnancy weeks are calculated based on the first day of the last menstrual period (LMP). In early pregnancy, ultrasound estimation is based on the gestational sac diameter, and as the embryo becomes visible, it is measured using the crown-rump length (CRL).

1. First Trimester Ultrasound Scans

First Ultrasound (5th–8th Week)

• Confirms the location of the implantation, determining whether the embryo is inside the uterus or an ectopic pregnancy.
• Evaluates the number of embryos, fetal heartbeat, and checks the uterine anatomy for any abnormalities such as fibroids.

Nuchal Translucency Scan (11th–13th Week)

• Measures fluid accumulation behind the fetal neck to assess the risk of Down syndrome and other chromosomal abnormalities.
• This test is not diagnostic but provides a risk percentage for these conditions.
• The final result also considers two biochemical markers:
  • Beta-hCG
  • PAPP-A (Pregnancy-Associated Plasma Protein A)
• A blood test is done alongside the ultrasound.

Supplementary Test: Non-Invasive Prenatal Testing (NIPT)

• A blood test for a more accurate assessment of risks for:
  • Trisomy 21 (Down Syndrome)
  • Trisomy 13 (Patau Syndrome)
  • Trisomy 18 (Edwards Syndrome)
• Recommended for:
  • Parents seeking a more precise screening
  • High-risk results from the nuchal translucency scan
• Can be done from the 10th week of pregnancy.
• Results available in ~2 weeks.
• If NIPT results are positive, it does not mean termination is necessary. Instead, invasive tests such as chorionic villus sampling (CVS) or amniocentesis are performed to confirm the diagnosis.

2. Second Trimester Ultrasound Scans

Anomaly Scan (20th–23rd Week) – Level 2 Ultrasound

A detailed examination of the fetus’s organs and systems, including:

• Head & Skull Bones
• Brain Anatomy
• Face: Lips, jawbones, nasal bone, eye sockets
• Neck Thickness (Nuchal Fold Measurement)
• Spine
• Heart Anatomy
• Thorax & Lungs
• Stomach, Kidneys, Liver, Intestines, Bladder
• Arms & Legs: Checks for all fingers and toes
• External Genitalia
• Placenta Position & Morphology
• Umbilical Cord
• Amniotic Fluid Levels
• Potential Indicators of Chromosomal Abnormalities

3. Third Trimester Ultrasound Scans

Growth & Doppler Ultrasound (30th–32nd Week)

• Evaluates blood flow resistance (PI) in the uterine arteries and umbilical cord to assess fetal nourishment.
• Biophysical Profile (BPP): Assesses:
  • Fetal breathing movements
  • Fetal body movements
  • Muscle tone
  • Amniotic fluid levels
  • Fetal heart rate (Cardiotocography - CTG/NST)

Growth Ultrasound (From 34th Week Onwards - Weekly)

• Fetal weight estimation
• Amniotic fluid volume measurement
• Umbilical cord blood flow assessment

4.  Fetal Monitoring (From the 36th Week)

Cardiotocography (CTG/NST – Non-Stress Test)

• A non-invasive test that monitors:
  • Fetal heart rate
  • Uterine contractions
  • Fetal movements
• The mother lies in a comfortable position (seated or reclined).
• The cardiotocograph consists of two sensors:

• 1. One sensor detects uterine contractions.
  2. The second sensor (with ultrasound gel) records the fetal heart rate.
• A button is given to the mother to press whenever fetal movement is felt.
• This test evaluates how the fetus responds to movements and uterine activity.
• CTG/NST is also used during labor.

This ultrasound schedule ensures comprehensive pregnancy monitoring, detecting potential complications and supporting fetal well-being throughout pregnancy