Pregnancy Loss Symptoms and Diagnosis Fetal Pole and Early Pregnancy Ultrasound 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 October 28, 2021 Medically reviewed Verywell Family articles are reviewed by board-certified physicians and family healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Brian Levine, MD, MS, FACOG Medically reviewed by Brian Levine, MD, MS, FACOG Brian Levine, MD, MS, FACOG, is board-certified in obstetrics-gynecology, as well as reproductive endocrinology and infertility (REI). He is the director and founding partner of CCRM New York and was named a rising star by Super Doctors from 2017 to 2019. Learn about our Medical Review Board Print Verywell / Jessica Olah Upon discovering that you're newly pregnant, your doctor may schedule you for an early pregnancy ultrasound. If the embryo isn't far enough along to have developed into a recognizable fetus, the ultrasound tech will look to identify a "fetal pole." The development of a fetal pole is one of the first stages of embryonic growth. If the fetal pole appears to be missing, you may be wondering whether everything is okay. Understanding a little background about the fetal pole can help you to feel more prepared for your first prenatal visit. Fetal Pole Function The fetal pole appears as a thick area alongside the yolk sac, which is a source of fetal nourishment at the beginning of pregnancy. The fetal pole is a preliminary structure that ultimately develops into a fetus. Curved in appearance, the fetal pole has the head of the embryo at one end and a tail-like structure at the other. The distance between these two points is used to measure the crown-to-rump length (CRL), which helps determine how far along you are in your pregnancy. Reasons for a Missing Fetal Pole There are a couple of possible reasons why the fetal pole may not be visible on an early ultrasound despite getting a positive pregnancy test. It's Too Early The fetal pole becomes visible somewhere between 5 1/2 and 6 1/2 weeks of gestational age (typically determined based on the date of the last normal menstrual period). Any small error in dating the pregnancy can throw off an ultrasound interpretation. For example, incorrectly remembering when you last had your period can change what your doctor will expect to see on an ultrasound. Healthcare providers typically use the first day of your last period (LMP) to initially date your pregnancy. Similarly, if you have an irregular cycle or do not always ovulate 14 days after you begin each period (an assumption based on the 28-day average cycle), your pregnancy may not technically be 5 to 6 weeks along—even if it has been 5 or 6 weeks since your last menstrual period. As a normal menstrual cycle can range anywhere from 21 to 35 days, it's not uncommon to ovulate much earlier or later than cycle day 14. If your doctor suspects that it's just too early into your pregnancy to detect a fetal pole, they may ask you to come back for a follow-up ultrasound a week or two later. The Pregnancy Is Not Viable If, however, you have a follow-up ultrasound and there's still no sign of a fetal pole (or a gestational sac, which looks like white rim around a clear center), a miscarriage has likely occurred. In some cases, the empty gestational sac can remain intact for a number of weeks before miscarriage symptoms appear. It may even continue to grow, as in the case of a blighted ovum. Other times, a miscarriage may be diagnosed by a single ultrasound that shows no fetal pole, such as if a gestational sac is larger than 25 millimeters but there is no accompanying fetal pole. A Word From Verywell Pregnancy is often filled with emotional ups and downs. It's normal to get your hopes up at the first sign of a positive pregnancy test. Discovering complications along the way can be devastating. While family and friends don't always know the best way to show support, there is help available. Speak to a therapist if you are struggling to cope with issues related to pregnancy or fertility. How to Cope After a Miscarriage Was this page helpful? Thanks for your feedback! Get diet and wellness tips delivered to your inbox. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 5 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. Cheng HH, Ou CY, Tsai CC, et al. Chromosome distribution of early miscarriages with present or absent embryos: Female predominance. J Assist Reprod Genet. 2014;31(8):1059-64. doi:10.1007/s10815-014-0261-9 Murugan VA, Murphy BO, Dupuis C, Goldstein A, Kim YH. Role of ultrasound in the evaluation of first-trimester Ppregnancies in the acute setting. Ultrasonography. 2020;39(2):178-189. doi:10.14366/usg.19043 American College of Obstetricians and Gynecologists. Methods for estimating the due date. Richardson A, Gallos I, Dobson S, Campbell BK, Coomarasamy A, Raine-Fenning N. 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