Pregnancy Ultrasound Scans: A Trimester-Wise Guide

Pregnancy is an exciting journey, and ultrasound scans play an important role in monitoring the health and development of your baby at each stage. If you are expecting, you may be curious about which scans are recommended, when they are typically performed, and what each one looks for.

This guide explains the key ultrasound scans that are commonly recommended during each trimester of pregnancy. It is written in simple, reassuring language for expecting mothers and their families.

This guide has been prepared by the radiology team at Shri Medscan Imaging Center, a diagnostic centre in Bhubaneswar, Odisha, offering ultrasound scans with experienced sonologists at two convenient locations.

Why Are Ultrasound Scans Important During Pregnancy?

Ultrasound scans during pregnancy allow your doctor to:

• Confirm the pregnancy and estimate the due date
• Check the baby’s heartbeat
• Monitor the baby’s growth and position
• Check the development of the baby’s organs
• Evaluate the placenta, amniotic fluid, and umbilical cord
• Identify potential concerns early so your doctor can plan the best care

Ultrasound uses sound waves, not radiation, to create images. It is considered safe for both mother and baby when performed by qualified professionals using standard clinical protocols. The number and timing of scans during your pregnancy will depend on your doctor’s recommendations based on your individual health and pregnancy history.

First Trimester Scans (Weeks 1 to 12)

The first trimester is a crucial period when the pregnancy is confirmed and early development is assessed. Two scans are commonly recommended during this stage.

Dating Scan (Usually Around 6 to 10 Weeks)

The dating scan is often the first ultrasound you will have during pregnancy. Its primary purpose is to:

• Confirm that the pregnancy is developing inside the uterus
• Detect the baby’s heartbeat
• Determine the gestational age of the pregnancy and estimate the due date
• Check whether you are carrying one baby or multiples (twins, triplets)

An early dating scan may require a full bladder, as this helps the sonologist get clearer images when the pregnancy is still very small. Your centre will give you specific instructions when you book. This scan is usually a quick procedure, typically taking about 15 to 20 minutes.

NT (Nuchal Translucency) Scan (Usually Around 11 to 14 Weeks)

The NT scan measures a small fluid-filled space at the back of the baby’s neck called the nuchal translucency. This measurement, combined with a blood test (if recommended by your doctor), helps assess certain developmental markers early in pregnancy.

The NT scan is a specialised measurement that needs to be performed within a specific window, typically between 11 weeks and 13 weeks 6 days. If your doctor recommends this scan, it is important to schedule it within the correct timeframe. The scan is performed on your abdomen (a full bladder is usually not required at this stage) and takes about 20 to 30 minutes.

Second Trimester Scans (Weeks 13 to 27)

The second trimester is when your baby grows significantly and organ development progresses. The most important scan during this period is the anomaly scan.

Anomaly Scan / Level 2 Scan (Usually Around 18 to 22 Weeks)

The anomaly scan (also called the Level 2 scan or mid-pregnancy scan) is one of the most detailed ultrasounds performed during pregnancy. It provides a thorough check of your baby’s developing organs and structures. During this scan, the sonologist will assess:

• The baby’s brain, spine, face, heart, stomach, kidneys, and limbs
• The position of the placenta
• The amount of amniotic fluid
• The umbilical cord

This scan typically takes 30 to 45 minutes, depending on the baby’s position and visibility. A full bladder is generally not required.

It is important to understand that while the anomaly scan checks the baby’s development in detail, no scan can detect every possible condition. Your obstetrician will discuss the findings with you and advise on any follow-up that may be needed.

Third Trimester Scans (Weeks 28 to 40)

In the final trimester, your doctor may recommend one or more scans to monitor the baby’s growth, position, and overall wellbeing as you approach delivery.

Growth and Wellbeing Scan (Usually Around 28 to 36 Weeks)

The growth scan checks whether your baby is growing at a healthy rate. It also evaluates:

• The baby’s estimated weight
• The baby’s position (head down, breech, or transverse)
• Placental position and health
• Amniotic fluid levels
• Blood flow through the umbilical cord (Doppler assessment, if ordered)

Your doctor may recommend one or more growth scans depending on your specific pregnancy. Conditions such as gestational diabetes, high blood pressure, or a history of growth-related concerns in previous pregnancies may require more frequent monitoring. A growth scan typically takes 15 to 30 minutes and does not require a full bladder.

Is Ultrasound Safe for Mother and Baby?

Yes. Ultrasound has been used in pregnancy care for decades and is considered safe when performed by qualified professionals following standard protocols. It uses sound waves to create images. Unlike X-rays or CT scans, ultrasound does not involve any ionising radiation.

At Shri Medscan, all pregnancy scans are performed by experienced sonologists who follow clinically established guidelines to keep exposure time within recommended limits.

While ultrasound is safe, it should only be performed when there is a clinical reason, as recommended by your doctor. It is not advisable to have scans done purely for non-medical reasons outside of your doctor’s recommended schedule.

How to Prepare for a Pregnancy Ultrasound

Quick Reference: Pregnancy Scan Schedule

Note: This is a general guide. Your obstetrician will decide the exact scan schedule based on your individual pregnancy.

Pregnancy Ultrasound Scans at Shri Medscan, Bhubaneswar

Shri Medscan Imaging Center offers pregnancy ultrasound scans at two locations:

We also offer pathology lab services for pregnancy-related blood tests and a full range of diagnostic services.

Frequently Asked Questions About Pregnancy Ultrasound

Disclaimer: This is a general guide. The exact scan schedule and timing should be decided by your treating obstetrician based on your individual pregnancy.
Medically reviewed by: Dr. Jailamala Sahoo, MD (Radiodiagnosis), Shri Medscan Imaging Center, Bhubaneswar.