The first pregnancy ultrasound is performed between weeks 6 and 13 of gestation, although the optimal time is usually at week 12 of pregnancy. In cases where pregnancy occurs through fertility treatment, the first ultrasound is normally performed at weeks 6-7 of pregnancy.
Through this ultrasound, the gynecologist will confirm pregnancy by observing the gestational sac or sacs and their location (intrauterine or extrauterine). This also helps to rule out a possible ectopic pregnancy and fetal abnormalities.
In addition to confirming the presence and type of pregnancy, the first trimester ultrasound allows examination of the female reproductive system and estimation of the fetal gestational age.
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What can be seen in the first trimester ultrasound?
The ultrasound that most comprehensively evaluates the anatomy and integrity of organs and systems is performed at week 20 of pregnancy. However, in the week 12 ultrasound, some of these features can already be identified.
The first pregnancy ultrasound can be performed either abdominally or vaginally, and often both methods are combined.
This first ultrasound is considered one of the most important. It evaluates parameters that assess the risk of chromosomal abnormalities, such as Down syndrome. Therefore, thanks to the week 12 ultrasound, it is possible to determine:
- Crown-Rump Length (CRL) of the fetus: this is the measurement of the embryo from the crown to the rump. At week 12 of pregnancy, this length should be around 6 cm, which allows calculation of the correct gestational age.
- Nuchal Translucency (NT) measurement: this is the accumulation of fluid in the cervical and posterior dorsal region of the fetus, observed before week 14 of pregnancy and usually disappears afterward. The posterior neck area of the embryo is measured. Along with other maternal blood parameters and embryonic ultrasound findings, this constitutes the chromosomal abnormality screening and may guide the potential need for further confirmatory invasive tests such as amniocentesis or chorionic villus sampling.
However, if the pregnancy did not occur naturally, but through artificial insemination (AI) or in vitro fertilization (IVF), the first ultrasound is usually performed before week 12.
First ultrasound after fertility treatment
Patients undergoing AI or IVF who test positive for beta-hCG should have their first ultrasound at around 6-7 weeks. At this stage, the specialist can confirm the pregnancy by visualizing the gestational sac and embryo. Additionally, this first ultrasound after IVF or AI will also indicate whether it is a singleton or multiple pregnancy.
Sometimes, the image may only show the gestational sac but not the embryo. This may be due to slow embryonic development or an anembryonic pregnancy.
If the ultrasound image is not entirely clear, it is recommended to repeat the scan to confirm the result.
Importance of the first gestational ultrasound
Regardless of whether the pregnancy was natural or via assisted reproductive techniques, the importance of the first pregnancy ultrasound is that it allows confirmation of the pregnancy, as it helps to:
- Determine the number of embryos and their location in the uterus. In the case of a twin pregnancy, the ultrasound can show whether the embryos share a placenta and/or amniotic sac.
- Check the heartbeat and its rate to confirm embryonic vitality.
- Estimate gestational age and the possible due date.
In addition, if the first pregnancy ultrasound takes place around week 12, it will also be possible to see the position of the placenta and even try to determine the sex of the fetus.
Risks
Ultrasounds pose no risk to women or fetuses. Unlike X-rays, ultrasound techniques do not involve radiation.
However, fetal ultrasound also has certain limitations, which may result in some defects not being detected before birth.
There are no contraindications for performing a first trimester ultrasound in any woman.
Tips for the first trimester ultrasound
When attending the first pregnancy ultrasound, no prior preparation is required. However, it is important to have a full bladder to obtain a high-quality image. It is recommended to drink two to three glasses of liquid about an hour before the scan and not to urinate until the procedure is finished.
Ultrasound waves are not felt, so the procedure is painless. The pregnant woman may experience slight discomfort due to a full bladder. She may also feel cold and wet from the use of the conductive gel.
Other general recommendations before the first trimester ultrasound include avoiding the use of moisturizing creams on the abdomen for at least two days prior to the scan, as these could interfere with the waves and reduce image clarity.
FAQs from users
When is the first pregnancy ultrasound after IVF?
It is usual to perform the first ultrasound scan in the 6th-7th week of pregnancy to confirm the pregnancy and to observe that the pregnancy is progressing correctly. Therefore, the first ultrasound test takes place about 3-5 weeks after the embryo transfer.
In this first ultrasound after IVF, the gestational sac, the yolk vesicle, the heartbeat and the embryonic bud will be observed.
When is the first pregnancy ultrasound performed?
The first ultrasound usually takes place during the first trimester of pregnancy. It is typically performed between weeks 6 and 12 to confirm the pregnancy.
The later it is done, the more information it provides. The purpose of this first gestational ultrasound is to observe the gestational sac and assess whether the embryo is implanted in the correct location or, conversely, if an ectopic pregnancy has occurred.
How long is the first trimester ultrasound scan?
The general duration of the first ultrasound of pregnancy is approximately 30 minutes, although it will depend on the position of the foetus.
If the foetus is not in a suitable position, it will make it difficult to see the foetus and measure the nuchal translucency, for example
Recommended readings
If you want to know how the baby develops throughout pregnancy, we recommend visiting the following article: How is the baby's development month by month? - Special care.
Additionally, sometimes only the gestational sac is visualized, not the embryo. For more information on this topic, you can continue reading here: What is anembryonic pregnancy? - Detection and treatment.
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References
Jenny Y Mei, Yalda Afshar, Lawrence D Platt. First-Trimester Ultrasound. Obstet Gynecol Clin North Am. 2019 Dec;46(4):829-852. doi: 10.1016/j.ogc.2019.07.011 (View)
Melissa Whitworth, Leanne Bricker, Clare Mullan. Ultrasound for fetal assessment in early pregnancy. Cochrane Database Syst Rev. 2015 Jul 14;2015(7):CD007058 (View)
Peter M Doubilet. Ultrasound evaluation of the first trimester. Radiol Clin North Am. 2014 Nov;52(6):1191-9. doi: 10.1016/j.rcl.2014.07.004.
Peter S Wang, Shuchi K Rodgers, Mindy M Horrow. Ultrasound of the First Trimester. Radiol Clin North Am. 2019 May;57(3):617-633. doi: 10.1016/j.rcl.2019.01.006.
T Dias, T Arcangeli, A Bhide, R Napolitano, S Mahsud-Dornan, B Thilaganathan. First-trimester ultrasound determination of chorionicity in twin pregnancy. Ultrasound Obstet Gynecol. 2011 Nov;38(5):530-2. doi: 10.1002/uog.8956. Epub 2011 May 3 (View)
FAQs from users: 'When is the first pregnancy ultrasound after IVF?', 'When is the first pregnancy ultrasound performed?' and 'How long is the first trimester ultrasound scan?'.
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