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. 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 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 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.
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. 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. For example, a gestational sac measuring 11 mm would be approximately 5 weeks and 4 days gestational age. This relies on the growth of the normal fetus of 1 mm per day after the 6th week of gestation.
Twins Twins Twins and other multiple gestations can usually be identified fairly early in pregnancy. They may be seen with two separate gestational sacs diamniotic, dichorionic twins. They may be seen as two fetal poles occupying the same gestational sac monochorionic twins.
It is useful to identify twins early as the prognosis varies, depending on the chorionicity and amnionicity of the twins. In these cases, one of the twins fails to grow and thrive.
Instead, its development arrests and it is reabsorbed, with no evidence at delivery of the twin pregnancy. It will prove useful to advise patients of this phenomenon who are found to have twins early in pregnancy. Missed Abortion A missed abortion is an abnormal pregnancy that is destined to miscarry. About one in five early pregnancies will not survive. These will grow for a while, with HCG in the urine and serum, but eventually will stop growing normally, and then will stop growing at all.
Most of these two-thirds will have abnormal chromosomes. Evidence of a missed abortion using high-resolution transvaginal scanning includes:. Absence of a visible fetal heartbeat when the CRL is greater than 5 mm. Absence of a fetal pole when the average sac diameter is more than 18 mm.
Loss of fetal cardiac activity that was previously seen. Read more about missed abortion. Such patients are frequently evaluated with ultrasound. About half of these will go on to miscarry while the other half will be normal. Detection of abnormal pregnancies that are destined to miscarry. Enabling scheduled intervention, if desired by the patient. Enabling collection of pregnancy tissue for chromosomal analysis, if desired by the patient.
Reassurance to the patients with normal ultrasound scans. Unfortunately, diagnosis of an abnormal pregnancy does not allow for intervention to correct the abnormality. Read more about threatened abortion. Incomplete Abortion Ultrasound is sometimes used after passage of pregnancy tissue to determine whether any pregnancy tissue remains inside the uterus. Findings will vary in these cases. Sometimes, it is obvious that there is nothing left inside the uterus, as evidenced by a thin, complete endometrial stripe.
In other cases, there will be obvious pregnancy tissue. In the remaining cases, some material will still be present inside the uterus, but it won't be clear on ultrasound whether this is blood, blood clot, or retained products of conception.
Read more about incomplete abortion. About Recent Edits Go ad-free. Edit article. View revision history Report problem with Article. Citation, DOI and article data. Radswiki, T. Fetal pole.
Reference article, Radiopaedia. URL of Article. Hung N. If a possible complication in early fetal development is suspected, your health care provider will use a combination of blood tests and ultrasound tests to make a clear diagnosis.
A blood test can be used to monitor hCG levels and progesterone levels. Ultrasounds can be used to visually see what development is taking place in the uterus and measure progress. Gestational age is the age of the pregnancy from the last normal menstrual period LMP , and fetal age is the actual age of the growing baby. Most references to pregnancy are usually in gestational age rather than fetal age development, but we have included both so that it is clear what stage development is being discussed.
At this stage, the menstrual period has just ended and your body is getting ready for ovulation. For most women, ovulation takes place about 11 — 21 days from the first day of the last menstrual period. During intercourse, several hundred million sperms are released into the vagina. Sperm will travel through the cervix and into the fallopian tubes.
When conception takes place, the sperm will penetrate an egg and create a single set of 46 chromosomes called a zygote — the basis for a new human being. The fertilized egg, called a morula, spends a couple of days traveling through the fallopian tube toward the uterus and dividing into cells this dividing process is where many chromosomal abnormalities occur.
The morula becomes a blastocyst and will eventually end up in the uterus. Anywhere from day 6 — 12 after conception, the blastocyst will embed into the uterine lining and begin the embryonic stage.
The endometrium lining thickens as the blastocyst burrows into it. A key fact to remember when choosing an ultrasound is that a transvaginal ultrasound can detect development in the uterus about a week earlier than a transabdominal ultrasound.
Once implantation occurs, the pregnancy hormone Human Chorionic Gonadotropin hCG will develop and begin to rise. This hormone will signal that you are pregnant on a pregnancy test.
A quantitative blood test measures the exact amount of hCG in the blood, and a qualitative hCG blood test simply detects the presence of hCG.
Doctors will often use the quantitative test if they are closely monitoring the development of a pregnancy. After implantation occurs, the hormone will begin to rise and should increase every hours for the next several weeks. The follicle from which the egg was released is called the corpus luteum.
It will release progesterone that helps thicken and prepare the uterine lining for implantation.
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