Is It Normal Not to See Gestational Sac on Ultrasound at 4-5 Weeks?

Ultrasound examination of the gestational sac?

Hello Dr.
Tsao, I would like to ask if it is normal not to see the gestational sac on an abdominal ultrasound when I am about four to five weeks pregnant.
On April 15, I visited a clinic for follicle tracking, and the doctor said that I had not ovulated yet.
The next day, on April 16, I returned for follow-up, and the egg had been released, with an endometrial thickness of 10.1 mm.
On April 29, I went to the clinic for a pregnancy test (13 days post-conception?), and the test showed two lines, with the second line being very faint.
The doctor estimated that I was about four weeks pregnant, with an endometrial thickness of 12.8 mm.
The doctor advised me to return the following week for a follow-up ultrasound to check for implantation.
The following week, on May 5 (19 or 20 days post-conception?; 4 weeks + 5 or 6 days?), I went to the clinic for an ultrasound, but despite having a full bladder, nothing was visible, not even a suspected gestational sac.
I am very worried.
The next day, I went to another clinic for a pregnancy test, and the test lines were almost equally dark.
The doctor looked at the test and said I was probably just under five weeks pregnant, and mentioned that at this stage, it is common not to see anything on the ultrasound, so they did not perform the abdominal ultrasound, and I went home.
I would like to ask the doctor if it is normal not to see anything on the abdominal ultrasound at this stage of pregnancy.
Should I expect to see something on the ultrasound if I go back in a week? Thank you, doctor.

Lily, 30~39 year old female. Ask Date: 2016/05/07

Dr. Cao Guotao reply Obstetrics and Gynecology

Hello, typically a standard ultrasound can detect the gestational sac at around 5 weeks.
Currently, the gestational sac seems to be unclear, so I recommend waiting another week to see if it becomes visible.
If the gestational sac is seen, there should be no issues; otherwise, there is a possibility of an ectopic pregnancy.
I suggest returning to your original obstetrician for continued monitoring.
Wishing you good health.

Reply Date: 2016/05/07

More Info

It is understandable to feel anxious when you are not able to see the gestational sac on an ultrasound at 4-5 weeks of pregnancy. Generally, it is important to note that at this early stage, it is quite common not to visualize the gestational sac using a transabdominal ultrasound. Typically, a gestational sac can be detected via transvaginal ultrasound around 4.5 to 5 weeks of gestation, while a transabdominal ultrasound may not show the sac until about 5 to 6 weeks.
In your case, since you are at approximately 4 weeks and 5-6 days, it is still within the range where the gestational sac may not be visible yet. The fact that you received a positive pregnancy test and your endometrial thickness is appropriate for early pregnancy are positive indicators. The endometrial thickness of 12.8 mm suggests that your body is preparing for a potential pregnancy, which is a good sign.

It is also important to consider that the timing of ovulation can vary, and if you ovulated later than expected, it could affect the timing of when the gestational sac becomes visible. Since you mentioned that you had a follow-up ultrasound scheduled for a week later, it is reasonable to expect that by then, if the pregnancy is progressing normally, the gestational sac should be visible on the ultrasound.

If the gestational sac is still not visible during your next ultrasound, your healthcare provider may consider other factors, such as the possibility of a miscarriage or an ectopic pregnancy. However, it is crucial to avoid jumping to conclusions at this stage. Many women have healthy pregnancies even when early ultrasounds do not show expected results.

In summary, it is not unusual to not see the gestational sac at 4-5 weeks of pregnancy, especially with a transabdominal ultrasound. It is advisable to follow up with your healthcare provider as scheduled, and they will be able to provide you with further guidance based on the results of your next ultrasound. In the meantime, try to stay positive and remember that early pregnancy can be unpredictable, and many factors can influence what is seen on an ultrasound. If you have any concerns or experience any unusual symptoms, do not hesitate to reach out to your healthcare provider for reassurance and support.

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