What is a Chorionic Bump in Pregnancy?

What is a Chorionic Bump in Pregnancy?

There’s a lot to know when it comes to pregnancy and all its possibilities.

One such thing is a chorionic bump.

But what exactly is it?

And what does it mean for pregnancy?

Let’s find out together.

In this article: 📝

  • What is a chorionic bump?
  • What causes a chorionic bump?
  • How common is a chorionic bump?
  • What does a chorionic bump mean for your pregnancy?
  • Do chorionic bumps go away?
  • The final word on chorionic bumps

What is a chorionic bump?

A chorionic bump is the medical term for a bulge in the choriodecidual surface of the gestational sac.

Um. What exactly?

Don’t worry.

We’re here to translate.

When you’re pregnant, the fetus forms inside an amniotic sac.

That’s essentially a bag of liquid that keeps them safe.

The amniotic sac sits inside a bigger sac called the gestational sac.

Because it’s larger, the gestational sac can be seen on an ultrasound earlier in pregnancy.

A sonographer (a medical professional who performs ultrasounds) will be able to identify it between four and five weeks after conception (usually at the first-trimester ultrasound evaluation).

It looks like a dark space surrounded by a white rim.

(Not everyone has an ultrasound this early, but there is a chance you might have one. Otherwise, you’ll have one later, at around 20 weeks.)

The white rim of the gestational sac is called the chorion.

It’s covered in a series of microscopic bumps called villi.

The inner surface of the chorion is the choriodecidual surface.

If you have a chorionic bump, ultrasound scans will show it as a small, white, rounded structure on this surface.

Unlike a live embryo, a chorionic bump won’t have a heartbeat.

Most commonly, sonographers identify it as a protrusion from the chorionic wall that has no vascularity (blood flow).

If your healthcare team picks up what they think is a chorionic bump, you’ll likely be booked in for a follow-up ultrasound to take another look as things develop.

What causes a chorionic bump?

Research into chorionic bumps is still at an early stage.

The causes aren’t clear, and the bump itself could be several different things:

  • A hematoma (blood clot)
  • An area of hemorrhage
  • Fluid that’s accumulated
  • A second pregnancy that’s been lost and is being reabsorbed into the body
  • Loss of one embryo in a twin pregnancy

How common is a chorionic bump?

Different studies have come up with different numbers for the probability of a chorionic bump during pregnancy.

A 2013 study of nearly 38,000 pregnancies found chorionic bumps in only 0.15% of cases.

Another study in 2019 put the rate higher, at 0.7%.

Whatever the precise number, it’s rare.

And that can make diagnosis difficult.

What does a chorionic bump mean for your pregnancy?

The frustrating answer is that it isn’t clear.

Chorionic bumps may be associated with complications in pregnancy.

One study, which looked at pregnancies between 2003 and 2010, found the rate of pregnancy loss was twice as high for women with chorionic bumps as for those without.

But other research points to more positive outcomes.

A 2015 study found that almost two-thirds of women diagnosed with a chorionic bump went on to deliver a baby.

And if the chorionic bump was the only issue with the pregnancy, that rate increased to 84%.

Do chorionic bumps go away?


Amongst the chorionic bump success stories, one case study from the UK shows how that can happen.

A woman experiencing pain and bleeding problems had an ultrasound less than five weeks into her pregnancy.

The sonographer spotted a round structure of some kind, but it wasn’t clear what it was.

A week later, another ultrasound showed the rounded structure looking more like a chorionic bump, probably the result of a blood clot.

The chorionic bump was still there at a 13-week scan.

But by 20 weeks, it had disappeared.

And the really great news?

She went on to have a perfectly healthy baby.

The final word on chorionic bumps

Chorionic bumps are rare, and they’re not well understood yet.

In some cases, they’re linked to pregnancy complications.

But many people with chorionic bumps go on to have healthy babies.

If you’ve been diagnosed with one, your sonographer has spotted something that’s easy to miss.

That means your pregnancy can be carefully monitored, you can be redirected to the right care at the right time, giving you the best possible chance of delivering a healthy baby.

The pregnancy road contains all sorts of ups and downs.

Know that you don’t have to travel it alone.

Join us on Peanut.

Support is available. ❤️


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