13 Weeks Pregnant Ultrasound: Procedure, Abnormalities & Accuracy

Ultrasound Scan at 13 Weeks of Pregnancy

Medically Reviewed By
Dr. Sabiha Anjum (Gynecologist/Obstetrician)
View more Gynecologist/Obstetrician Our Panel of Experts

If you are 13 weeks pregnant, then it’s time that you have a little celebration as you are in the safe zone now. Every stage of pregnancy is important (and can be risky), but women have a sigh of relief once they pass the first 12 weeks of pregnancy, as the chances of miscarriage lower considerably once a pregnant woman reaches the 13th week of her pregnancy.

From this week onwards, your baby will grow rapidly and your doctor might suggest an ultrasound scan to check his progress. An ultrasound scan in the 13th week can tell you a lot about your baby’s health and is important. So read on to know why you should have an ultrasound scan at 13 weeks and how it is performed.

What Is a 13th Week Pregnancy Scan?

The 13 weeks pregnant ultrasound is also known as the anomaly ultrasound. It’s an extensive medical ultrasound between 12+3 and 14+3 weeks. It is where the possible congenital abnormalities are examined. Thankfully, these are uncommon, and most babies are born healthy.

The 13 week fetus ultrasound is done to examine if the baby may have an open back and/or skull or any abnormalities of other organs, like the brain, face, heart, stomach, bowels, etc. Also, various checks are performed on the baby’s growth, the amount of amniotic fluid and the position of the placenta.

Signs of Pregnancy at 13 Weeks

Confused what are the signs of pregnancy at 13 weeks? We have mentioned some signs for you below that you may be able to notice at this stage.

  • Frequent, urgent, or painful urination
  • Pain or cramping in the lower abdomen
  • Back pain
  • Cloudy, foul-smelling, or bloody urine
  • Shivering or chills

Why Should You Have an Ultrasound at 13 Weeks?

Performing an ultrasound scan at 13 weeks of pregnancy can help your doctor understand how your baby is developing. By this time, your baby’s kidney should function and he should have a urinary tract system. It means that your little should start peeing in the utero. His fingerprints will also take shape by this time. A scan performed in this week can help detect how he is progressing. It will also tell you how his other organs are coming along apart from his head.

Development of Baby at 13 Weeks Pregnant

Let’s take a look at the development of your baby at 13 weeks:

  • The baby is around 7.5 cm long – approximately the size of a peach or peapod.
  • The testes or ovaries of the baby are now fully developed.
  • The baby can now swallow small amounts of amniotic fluid and excrete urine.
  • As the baby swallows the amniotic fluid, they will also produce meconium- a black, sticky substance which accumulates in their bowels and becomes their first poop.

How to Prepare for Your 13th Week Pregnancy Scan?

This is one of the most significant ultrasounds performed during the pregnancy phase. And to prepare for your 13th-week ultrasound scan, you should drink lots of water before the scan, as it is essential to keep your bladder full during the ultrasound. This will help the technician get a clearer image of the foetus in your belly.

How Long Does It Take to Perform an Ultrasound Scan?

A 13 week sonogram can take around 15 to 30 minutes and can go up to 45 minutes if the baby is lying in an awkward position. But the duration of the scan will also depend on the technician who conducts it and on your baby’s position in your belly.


How is an Ultrasound Scan Performed?

To perform 13 week pregnancy sonography, the sonographer will ask you to lie down on the examination table and expose your belly. The sonographer will then apply some gel on your belly and press a transducer on your belly. The purpose of applying the gel is to make sure that a good connection is established between the skin and the transducer device. The device will be adjusted based on the image of the baby that is seen on the screen. The sonographer may apply some pressure on your belly to get a clear view of the baby. But don’t worry, as you will not experience pain during this process.

What Will You See on the Scan at the Thirteenth Week of Your Pregnancy?

An ultrasound scan performed in the 13th week of your pregnancy will reveal a lot of minute details about your baby. You will be able to hear your baby’s heartbeat and notice that some of his body parts have developed. In the earlier scans, you must have noticed that your baby’s head was slightly more prominent and bigger as compared to the rest of the body, but now your baby’s other parts of the body will develop fast and you will notice the size of the head becoming proportionate to the body. The scan will also indicate any abnormalities (if any) in the baby and other details of the development. During the 13th week ultrasound, Down’s syndrome can also be detected by measuring the nuchal thickness.

What If Some Abnormalities Are Discovered in the Scan?

If any problem is detected during the ultrasound, your doctor will give you more clarity about the health of your baby and your situation. Sometimes doctors even suggest a few more scans and some specific tests to ascertain the full extent of the abnormalities before coming to any conclusion.


1. Is 13 Week Ultrasound Scan Accurate?

The accuracy of 13 week pregnancy sonogram can vary from 70.3% at 11 weeks to 98.7% at 12 weeks and 100% at 13 weeks.

An ultrasound will help you connect with your little one in your belly. All this while you could feel the life inside of you, but now you will get to see your baby develop and come to life. These will be the significant moments of your pregnancy journey. If there are abnormalities that are detected, don’t let it dishearten you too much at this point, instead, talk to your doctor and see what can be done about it.


1. 13 Weeks Pregnant; americanpregnancy.org; https://americanpregnancy.org/healthy-pregnancy/week-by-week/13-weeks-pregnant/

2. 11-13 week antenatal scan; radiopaedia.org; https://radiopaedia.org/articles/11-13-week-antenatal-scan

3. Week 13; kidshealth.org; https://kidshealth.org/en/parents/week13.html

4. Pregnancy at week 13; pregnancybirthbaby.org.au; https://www.pregnancybirthbaby.org.au/pregnancy-at-week-13

5. 13 weeks pregnant: baby’s development, constipation and healthy eating; tommys.org; https://www.tommys.org/pregnancy-information/im-pregnant/pregnancy-week-by-week/13-weeks-pregnant

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