Pregnancy Scan Guide: Preparation, Purpose & Timing of Each Scan
Pregnancy is a journey filled with excitement, curiosity, and responsibility. One of the most important tools that doctors use to monitor a baby’s health during this journey is the pregnancy ultrasound scan. Each scan provides valuable information about the baby’s growth, development, and well-being at different stages of pregnancy.
At Nisarga Diagnostics, pregnancy scans are performed using advanced ultrasound technology and expert radiologists to ensure accuracy, safety, and reassurance for expecting parents. This comprehensive pregnancy scan guide explains the top 4 essential pregnancy scans, their purpose, correct timing, and preparation required for each.
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Why Are Pregnancy Scans Important?
Pregnancy ultrasound scans help doctors to:
Monitor baby’s growth and development
Confirm normal fetal anatomy
Detect complications at an early stage
Assess placenta and amniotic fluid
Plan safe pregnancy and delivery
Regular and timely scans allow early intervention and better pregnancy outcomes.
1. First Trimester Scan / Dating Scan (6–9 Weeks)
What is the purpose of this scan?
The first trimester scan, also known as the dating scan, is usually the first ultrasound performed after pregnancy confirmation. It helps to:
Confirm that the pregnancy is inside the uterus
Detect fetal heartbeat
Measure crown–rump length (CRL)
Accurately calculate gestational age
Determine the expected due date (EDD)
Identify multiple pregnancies, if present
This scan forms the foundation for all future pregnancy monitoring.
When is it done?
Between 6 and 9 weeks of pregnancy
Preparation for the dating scan
Drink 2–3 glasses of water
Come with a moderately full bladder
No fasting is required
A full bladder helps improve image clarity in early pregnancy ultrasound scans.
2. NT Scan / First Trimester Screening (11–13 Weeks)
What is the purpose of the NT scan?
The NT (Nuchal Translucency) scan is an important screening test that assesses the risk of chromosomal abnormalities such as:
Down syndrome (Trisomy 21)
Trisomy 18 and Trisomy 13
This scan also evaluates:
Thickness of fluid behind the baby’s neck
Nasal bone
Early fetal anatomy
Fetal heart activity
The NT scan is often combined with blood tests for more accurate screening.
When is it done?
Between 11 weeks and 13 weeks 6 days
This scan is strictly time-bound and should not be delayed.
Preparation for the NT scan
Light meals are allowed
A partially full bladder is preferred
Carry previous scan reports
Proper timing and preparation are crucial for reliable results.
3. Anomaly Scan / Level-2 Scan (18–22 Weeks)
What is the purpose of the anomaly scan?
The anomaly scan is one of the most detailed and important pregnancy ultrasound scans. It carefully examines the baby’s anatomy to identify structural abnormalities.
This scan evaluates:
Brain and spine
Heart structure and chambers
Kidneys and urinary system
Limbs and facial structures
Placenta location
Amniotic fluid volume
It provides reassurance about normal development or helps detect issues early.
When is it done?
Between 18 and 22 weeks of pregnancy
Preparation for the anomaly scan
No fasting required
No full bladder required
Wear comfortable clothing
This scan may take longer, as each organ is assessed carefully.
4. Growth Scan / Third Trimester Scan (28–36 Weeks)
What is the purpose of the growth scan?
The growth scan monitors how the baby is growing in the later stages of pregnancy. It helps doctors assess:
Baby’s estimated weight
Growth pattern over time
Amniotic fluid levels
Placenta function
Baby’s position (head-down or breech)
Blood flow using Doppler (if required)
This scan helps detect conditions like IUGR (intrauterine growth restriction) or excessive fetal growth.
When is it done?
Between 28 and 36 weeks, and may be repeated if needed
Preparation for the growth scan
No fasting required
No bladder preparation needed
Bring all previous pregnancy scan reports
Conclusion
Each pregnancy scan plays a unique role in ensuring a healthy pregnancy and safe delivery. Knowing when each scan is done, why it is important, and how to prepare helps parents stay informed and stress-free.
For reliable, accurate, and expert pregnancy ultrasound scans, Nisarga Diagnostics is committed to supporting you throughout your pregnancy journey.
Founder of Nisarga Diagnostics, is a renowned fetal ultrasound specialist with over 20 years of expertise. An alumnus of Government Medical Colleges in Mysore and Bangalore, he also holds a D.N.B. from the National Board of Examinations, Delhi, and certification from the Fetal Medicine Foundation, London. A former Professor and HOD, he has trained countless PG students and junior radiologists, shaping the future of fetal imaging in India.