Pregnancy Loss Symptoms and Diagnosis What Does No Gestational Sac on My Ultrasound Mean? By Krissi Danielsson Krissi Danielsson Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage. Learn about our editorial process Updated on September 16, 2022 Medically reviewed by Meredith Shur, MD Medically reviewed by Meredith Shur, MD Meredith Shur, MD, FACOG, is board-certified in obstetrics and gynecology, as well as a certified medical examiner. Learn about our Medical Review Board Print Verywell / Gary Ferster Table of Contents View All Table of Contents When Is It Visible? Common Causes What to Do You will understandably be worried if you go in for a pregnancy ultrasound but are told that a gestational sac could not be seen. Unfortunately, you can have a positive pregnancy test but not see a baby on the ultrasound. The gestational sac encloses the developing baby and contains amniotic fluid. If it's not visible by around 5 weeks gestation, it may mean that the pregnancy is not viable or a miscarriage has already happened. However, you may have your timing off and it's just too early to see, in which case, a follow-up ultrasound will likely be ordered. Learn more about when the gestational sac is usually seen and the different reasons why it can't be found on an ultrasound in early pregnancy. 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 4 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 a transvaginal ultrasound. When Does the Gestational Sac Become Visible on an 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. When No Sac Is Visible If a gestational sac is not visible, it could mean that:It is too early in the pregnancy.The pregnancy is ectopic.The pregnancy is a miscarriage. 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. Incorrect timing is one of the most common causes of an inability to see a gestational sac on an early ultrasound, especially in the absence of symptoms such as bleeding. If the pregnancy is definitely past 5 weeks, or the hCG level is higher than 2000, a finding of no gestational sac is more likely to indicate a problem. The Best Way to Track a Pregnancy Ectopic Pregnancy 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. A doctor may be able to diagnose ectopic pregnancy and recommend treatment without a follow-up ultrasound if the hCG levels are high enough that the gestational sac would definitely be visible if the pregnancy was located in the uterus. These pregnancies are not always medical emergencies when detected early, and treatment options are not always surgical. Risk Factors of Ectopic Pregnancies 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. Symptoms and Signs of an Impending 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. 4 Sources Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Rodgers SK, Chang C, DeBardeleben JT, Horrow MM. Normal and abnormal us findings in early first-trimester pregnancy: review of the society of radiologists in ultrasound 2012 consensus panel recommendations. RadioGraphics. 2015;35(7):2135-2148. doi:10.1148/rg.2015150092 Murugan VA, Murphy BO, Dupuis C, Goldstein A, Kim YH. Role of ultrasound in the evaluation of first-trimester pregnancies in the acute setting. Ultrasonography. 2020;39(2):178-189. doi:10.14366/usg.19043 Puget C, Joueidi Y, Bauville E, et al. Serial hCG and progesterone levels to predict early pregnancy outcomes in pregnancies of uncertain viability: A prospective study. Eur J Obstet Gynecol Reprod Biol. 2018;220:100-105. doi:10.1016/j.ejogrb.2017.11.020 ACOG practice bulletin no. 191: tubal ectopic pregnancy. Obstetrics & Gynecology. 2018;131(2):e65-e77. doi:10.1097/AOG.0000000000002464 Additional Reading Richardson A, Gallos I, Dobson S, Campbell B, Coomarasamy A, Raine-Fenning, N. Accuracy of first-trimester ultrasound in diagnosis of intrauterine pregnancy prior to visualization of the yok sac? A systematic review and meta-analysis. Ultrasound in Obstetrics and Gynecology. 2015;46(2):142-9. doi:10.1002/uog.14725 Cunningham, F.G., and J Whitridge Williams. Williams Obstetrics. New York: McGraw-Hill Education Medical, 2014. Print. By Krissi Danielsson Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit