Can blood test be wrong about pregnancy

You’ve missed your period and have a positive home pregnancy test. Now what?

You might decide to confirm pregnancy with a blood test, called the beta hCG test.

Want to know a little more about the blood test and what to expect? Check out the information below.

In pregnancy, urine and blood tests work by detecting a hormone that is made when a fertilized egg implants in the uterus.

This hormone is called human chorionic gonadotropin (hCG) and is found in your urine or blood.

Blood tests are about 99% accurate and can detect lower levels of hCG than a urine test.

Which blood test for pregnancy?

There are two types of blood pregnancy tests:

  • Qualitative blood serum test. This confirms whether or not hCG is present, basically offering a yes or no result. A qualitative hCG test has the same accuracy as a pregnancy urine test.
  • Quantitative blood serum test (beta hCG test). This blood test measures the actual amount of hCG in your blood. Because this test can detect even trace amounts of hCG, it’s highly accurate and can give you an idea of how many weeks pregnant you are.

Discuss with your doctor which test is appropriate for you.

How early can you get a pregnancy blood test?

You can have an hCG hormone blood pregnancy test as early as 11–14 days after ovulation.

Usually, doctors recommend waiting until after the first day of your missed period before having a blood test. This is usually 14 days after you’ve ovulated and conceived.

Most women will do a home urine test first. This home pregnancy test is easy to use and will give you an immediate result.

It’s important to know that a small percentage of home pregnancy tests will give a false positive.

You can then contact your doctor’s office for an appointment or more information on an hCG quantitative blood test.

Please read more in How Accurate Is An Early Pregnancy Test?

Pregnancy blood test near me

Most women who suspect they’re pregnant usually do a home urine pregnancy test first.

Your local doctor can organize a pregnancy blood test through a pathology lab of your choice.

How long do pregnancy blood test results take?

Most blood pregnancy test results will be back with 48 hours or sooner, depending on who does the test for you.

Depending on your care provider, you might be sent the results directly, or you might have to make a follow-up appointment to get the results in the clinic.

How many pregnancy blood tests?

Prenatal care involves several blood tests. Bear in mind, these tests aren’t mandatory so you can choose to have some, all, or none of them.

Before you decide to have a test, get all the information about what it’s for and what you want to get from the information.

These are the main pregnancy blood tests you’ll be offered:

  • As a standard, an initial hCG blood test, which is done to confirm pregnancy
  • An early pregnancy antenatal screen, for a range of STIs, iron levels, blood type, immunity for rubella, and some genetic disorders
  • If you’re choosing to test for Down syndrome, this test happens before 13 weeks
  • The NIPT (non-invasive prenatal test) test, to check for fetal abnormality; this can be done in the first trimester after 10 weeks
  • Blood test at 24-26 weeks, for GDM and to retest your iron and vitamin levels
  • A further test at around 34-36 weeks, to monitor iron levels again close to the time of birth.

However, if your pregnancy has complications, you could have further blood and urine tests.

You might be interested in reading Finger Prick Test Can Tell Baby’s Sex In First Trimester.

Can I eat before the pregnancy blood sample test?

For most tests, it’s recommended you have something to eat beforehand. This is mainly because you might feel a little nauseous or light-headed if your blood sugar is low.

For a few tests, it’s recommended you don’t eat; your health care provider should let you know when giving you the referral.

The GTT (glucose tolerance test) for GDM (gestational diabetes mellitus) is a fasting test. You need to take nil by mouth overnight for this one.

Can the blood test tell me how many weeks pregnant?

The quantitative hCG test measures the exact amount of hCG in your blood.

The level can be interpreted to give an approximate number of weeks of pregnancy.

hCG Levels – What Should They Be Each Week? looks at the expected hCG levels each week of pregnancy.

Pregnancy blood test for gender

The non-invasive prenatal test (NIPT) has been around for about a decade. It screens for fetal abnormalities in a baby in the first trimester of pregnancy.

The test can also check your baby’s gender and check for any sex chromosome problems.

The NIPT test analyses the blood of the expectant mother and isolates pieces of the baby’s DNA that float around in her blood.

The accuracy of the NIPT test for identifying the sex of your baby is very high – over 99%.

The accuracy increases with gestational age:

  • Before week 7 = 74.5% accurate
  • Between weeks 7 and 12 = 94.8%
  • After week 20 = 99%.

Pregnancy blood test for Down syndrome

The nuchal scan or nuchal translucency scan is part of your 12-week ultrasound screening, which includes a blood test.

It checks for chromosomal abnormalities, focusing on the space at the back of your baby’s neck, called the nuchal fold.

In babies with chromosomal abnormalities, this area will accumulate fluid. Increased fluid is more likely to be linked to chromosomal problems, including Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), or Patau syndrome (trisomy 13).

The nuchal scan is combined with the mother’s age and results of the blood test to provide a ‘combined risk’.

The blood test looks for levels of pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotropin (hCG).

The nuchal scan accuracy for predicting Down syndrome is 75% without the blood test and 85% with the blood test.

You might be interested in reading this article Expecting a Baby With Down Syndrome – A Mother’s Story.

Pregnancy blood tests cost

If you choose to go public for pregnancy and birth care, the blood test is free in most countries. In Australia, the cost is paid by Medicare.

If you decide to have your pregnancy and birth care through the private health care system, there might be a cost associated with the pathology lab fee.

If you have private health insurance, you could be reimbursed some of your out-of-pocket costs for a blood pregnancy test; otherwise, you will be charged a full fee.

Commercial genetic blood testing involves a fee, as it is usually done in a private capacity.

These links below will give you more information around public vs private care:

  • Birth Options In Australia: Public, Private, Birth Centre, or Home?
  • How Much Does It Cost To Give Birth In Australia?
  • Who Cares? Maternity Care Options For Australian Women.

Does the pregnancy blood test hurt?

For most women, the test is like a little scratch in the arm and doesn’t hurt.

If you have an inexperienced phlebotomist, who might have trouble finding a vein, or if you have tricky veins to access, it could be a little more painful.

Feeling anxious or stressed about the test can make your muscles tense up, which can increase your perception of pain. Try to relax your body and use distraction techniques if you can.

Sometimes you will be left with a little bruise at the site of the test.

Can I lie down for a pregnancy blood sample test?

Of course! Not all of us are great with a hCG blood test, and some of us have a needle phobia.

If you usually feel light-headed or are super anxious about needles or having blood drawn, let your doctor or health professional know. They can do their best to make sure you’re comfortable and prepared for the test.

Can my midwife do my pregnancy blood tests?

Most women are given a referral form by their care providers. This form is taken to the pathology lab for blood or urine tests.

Private midwives might be able to do any blood tests in their clinic, or do a home pregnancy test.

How do you tell if you’re pregnant without the pregnancy test?

In times past, women didn’t have pregnancy tests to tell them whether or not they were pregnant. Most women use home pregnancy urine tests to confirm the pregnancy.

But if you can’t or don’t want to take a test, you can tell you’re pregnant by these signs:

  • Missed period
  • Tender, swollen breasts
  • Nausea, with or without vomiting
  • Increased urination
  • Fatigue.

For more information please read Pregnancy Symptoms | 16 Signs Of Pregnancy.

Can the pregnancy blood test be wrong?

As with urine tests and home pregnancy tests, it’s possible to end up with false results (either false negative or false positive results) from a blood pregnancy test.

A false negative (a negative result when you are pregnant) can occur if the blood pregnancy test was performed too early.

There might not be enough hCG in the blood to detect a pregnancy.

If you believe you’ve received a false negative from testing too soon, your doctor can repeat the hCG blood test after 48 to 72 hours.

False-positive pregnancy tests (test is positive, but you’re not pregnant) very rarely happen.

You might get a false-positive result if you’re taking a medication that contains the hormone hCG (such as when you are undergoing fertility treatments), or if you have certain medical problems.

For more information, please read False Positive Pregnancy Test – 7 Causes Of An Inaccurate Result.

Possible risks of a blood test in pregnancy

There is very little risk associated with getting an hCG blood test.

You might feel lightheaded and faint, or have bleeding, infection, or bruising at the puncture site, or develop a hematoma (when blood accumulates under the skin).

Because veins and arteries differ in size from one person to another (and from one side of the body to the other), getting a blood sample could be more difficult for some people.

In order to get the required blood sample, you might need multiple attempts to locate a vein.

How often are pregnancy blood tests wrong?

Blood test results are about 99 per cent accurate and can detect lower amounts of hCG than urine pregnancy tests.

How accurate are blood test results for pregnancy?

A pregnancy blood test is done in a health care provider's office. It can find smaller amounts of HCG, and can confirm or rule out a pregnancy earlier than a urine test. A blood test can detect pregnancy even before you've missed a period. Pregnancy blood tests are about 99 percent accurate.

What can cause a false blood pregnancy test?

This is known as a false-positive. A false-positive might happen if you had a pregnancy loss soon after the fertilized egg attached to your uterine lining (biochemical pregnancy) or you take a pregnancy test too soon after taking a fertility drug that contains HCG .

Can you have hCG and not be pregnant?

An elevated β-hCG in the absence of viable pregnancy can occur for multiple reasons and has a broad differential diagnosis including miscarriage, ectopic pregnancy, pituitary hCG production, trophoblastic disease and phantom hCG.

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