Fetal Pole

A fetal pole is an embryo, one of the first stages of pregnancy. In a healthy pregnancy, the fetal pole develops into a fetus. An early prenatal ultrasound can view and measure the fetal pole. This provides information about the embryo’s location, gestational age, possible complications and whether there’s more than one embryo.


What is a fetal pole?

A fetal pole is one of the first stages of an embryo’s development in pregnancy. During a healthy pregnancy, the fetal pole develops into a fetus, then an infant. It’s also called an embryo or embryonic pole.


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Is a fetal pole a baby?

Medically speaking, a fetal pole isn’t yet a baby. It’s an embryo until about the 10th week of gestation. It then becomes a fetus and goes through fetal development until birth.


What is the role of the fetal pole?

Healthcare providers can see and measure a fetal pole using prenatal ultrasound. The images can provide important information to healthcare providers early in pregnancy, such as:

  • How long the embryo has been developing: The size of the fetal pole can help determine gestational age, especially if you’re unsure of the date of your last period or if your periods are irregular.
  • How many embryos there are: If you’re pregnant with multiples, there will be multiple fetal poles.
  • Where the pregnancy is located: A viable pregnancy should be in your uterus, rather than your fallopian tubes, for example.
  • Whether there’s a pregnancy complication: If the fetal pole is unexpectedly small or not seen, it may indicate incorrect dates or a miscarriage.


Where is the fetal pole located?

A fetal pole is located next to a small pouch called the yolk sac. That’s where it gets its nutrients. The fetal pole and yolk sac are contained inside the gestational sac. In a normal pregnancy, the gestational sac is in your uterus.

What does a fetal pole look like?

A fetal pole is curved. At one end is the head of the embryo, called the crown. At the other end, there’s a tail-like structure, called the rump.


How big is an embryo?

A fetal pole’s size depends on how far along the pregnancy is. An embryo is measured from the crown to rump (crown-to-rump length, or CRL).

When an embryo is first detected, it may be only 1 or 2 millimeters. It grows to about 30 millimeters by the 10th week of pregnancy.

When does the fetal pole appear?

A fetal pole is often visible with vaginal ultrasound at about five and a half weeks of pregnancy. But sometimes it’s not seen for several weeks, depending on the type of ultrasound and the angle of your uterus.

What comes first, fetal pole or heartbeat?

A heartbeat often is visible around six weeks of gestation, or soon after your provider sees the fetal pole.

Conditions and Disorders

What does it mean if the fetal pole is missing?

If ultrasound cannot locate the fetal pole when expected, you may need a repeat test in a few days.

An absent fetal pole can mean several things, including:

  • Blighted ovum: A blighted ovum (anembryonic pregnancy) is when a fertilized egg implants in the uterus but doesn’t grow into an embryo. This causes an early miscarriage.
  • Too early: If a pregnancy isn’t far enough along, you may not be able to see the embryo yet. Gestational age is based on an estimate and is often incorrect especially if your menstrual cycles have been irregular.
  • Miscarriage: If ultrasound cannot locate a fetal pole and/or gestational sac, you may have had a miscarriage.

If a fetal pole is found anywhere other than your uterus, it’s considered an ectopic pregnancy. The condition is a medical emergency and not a viable pregnancy. Other places a gestational sac may be found include:

  • Abdomen.
  • Cervix.
  • Fallopian tube (most common).
  • Ovary.

What if I have a fetal pole with no heartbeat?

If a fetal pole measures more than 7 millimeters and your provider doesn’t see a heartbeat, this is an abnormal pregnancy and will result in a miscarriage.

Your healthcare provider will help you understand your situation. They may order other tests to learn more.


What can I do to keep a fetal pole healthy and viable?

Many problems that occur with the fetal pole cannot be prevented. For example, there’s no way to change the location of an ectopic pregnancy or to prevent genetic problems that can lead to miscarriage after you’re pregnant.

But several strategies can help you and your embryo be as healthy as possible:

  • Avoid foods containing mercury, raw eggs or meats, or unpasteurized dairy products.
  • Consult your healthcare provider about any prescription or over-the-counter medications or supplements you take.
  • Don’t smoke or use tobacco products.
  • Don't drink alcohol or use recreational drugs.
  • Drink plenty of water.
  • Eat well, including fruits, veggies, whole grains, proteins and healthy fats.
  • Exercise.
  • Limit caffeine.
  • Take a prenatal vitamin every day.

A note from Cleveland Clinic

A fetal pole is an embryo, one of the first stages of pregnancy. During a healthy pregnancy, a fetal pole develops into a fetus, then a baby at birth. Talk to your healthcare provider about the results of your prenatal ultrasound and what they mean for your pregnancy.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 03/21/2022.

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