Good day, Doc, I tested positive for blood and urine tests but no sac was seen in an ultrasound. I was told to do a repeat test in two weeks’ time. Please what could have gone the wrong sir?
Worrying is normal and common in pregnancy. As a pregnant woman, you may be concerned when you go in for a pregnancy ultrasound only to hear that a gestational sac could not be seen. The gestational sac encloses the developing baby and contains amniotic fluid. The sac is the clinical evidence of a normally developing baby.
When Is a Gestational Sac Visible?
A gestational sac is one of the first signs of pregnancy that can be seen on a transvaginal ultrasound. The transvaginal ultrasound is generally used because an abdominal ultrasound is much less accurate this early in pregnancy.
The gestational sac is usually seen on ultrasound by 5 weeks gestational age but is sometimes seen as early as 3 weeks gestational age.
When identified on the ultrasound, the diameter of the sac is around 2 to 3 millimeters and is seen as a white rim around a clear center in your uterus. If you are also having quantitative pregnancy tests (serum hCG tests) the gestational sac usually becomes visible when hCG levels have reached 1500 to 2000.
The next step on ultrasound is usually the appearance of the yolk sac within the gestational sac. The yolk sac functions as nourishment for the developing embryo and can usually be seen by 5.5 to 6 weeks gestational age on transvaginal ultrasound.
Common Reasons for No Gestational Sac
• Having a gestational sac does not say much about the health of your pregnancy, nor does it say whether an embryo is present or not.
• The gestational sac is essentially the sac that surrounds the baby (when it becomes visible) and contains amniotic fluid.
• If a gestational sac is not seen on an early pregnancy transvaginal ultrasound by around 5 weeks gestational age, there are several things that could be occurring.
If a gestational sac is not visible, it could mean that:
- It is too early in the pregnancy
The gestational sac is typically visible on a transvaginal ultrasound somewhere between 3 to 5 weeks of pregnancy, or by the time the hCG has reached 1500 to 2000. Before that, even in a viable pregnancy, there is not going to be a visible gestational sac on an ultrasound.
But when there’s no confirmation of hCG levels or any definite evidence of the dating of the pregnancy, the pregnancy might still be in very early stages. In this case, a follow-up ultrasound is recommended.
- The pregnancy is ectopic
Whenever there is no gestational sac visible in the uterus, there is a possibility of ectopic pregnancy. This can be frightening, but keep in mind that the absence of a gestational sac is more likely to be related to wrong dates.
Even if an ectopic pregnancy is detected, these can be managed well when caught early. An ectopic pregnancy is still a possibility even if you don’t have symptoms of an ectopic pregnancy.
- The pregnancy is a miscarriage
If you have experienced early pregnancy bleeding or other miscarriage symptoms, a finding of no gestational sac may mean that you’ve had a very early miscarriage (also called a chemical pregnancy) or that the pregnancy tissue has already left the uterus.
If there are falling hCG levels along with a finding of no gestational sac, the diagnosis is almost certain to be a miscarriage. As with an ectopic pregnancy, there are different treatment options available if you have a miscarriage.
What to Do If There Is No Gestational Sac
• It can be difficult for doctors to determine right away which of the above explanations is behind a pregnancy with no visible gestational sac.
• Therefore, it is completely natural to feel concerned and anxious, and perhaps even frustrated.
• You may be told (or see on medical forms) that you have a “pregnancy of unknown location,” which simply means that the ultrasound did not show a gestational sac, and the doctors are not sure whether it is an ectopic pregnancy, a miscarriage, or a very early but otherwise normal pregnancy.
• Most likely, you will be asked to come back for a follow-up ultrasound and undergo monitoring of your hCG levels.
• Together, these repeat tests should give you a clear answer. The wait can be difficult but may be necessary for your doctor to be certain of your diagnosis.