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Understanding The Statistics Behind NIPT (Non-Invasive Prenatal Testing)

Written by London Pregnancy Clinic on . Posted in Blog, NIPT, NIPT, Obstetrics, Ultrasound. No Comments on Understanding The Statistics Behind NIPT (Non-Invasive Prenatal Testing)

Summary:

The best NIPT will be really good at detecting problems (high sensitivity) and correctly saying everything is fine (high specificity). It should hardly ever make mistakes by saying there’s a problem when there isn’t (low false positive) or missing a problem and saying everything is okay (low false negative). If the test says there’s an issue, it should be highly likely to be true (high positive predictive value). And if it says everything is fine, it should be trustworthy (high negative predictive value).

NIPT (non-invasive prenatal testing) is a type of genetic test used to screen for certain chromosomal abnormalities and genetic syndromes in a developing fetus. The test involves analyzing a sample of the mother’s blood to look for fragments of DNA from the fetus.

It’s good to know the statistical terms related to NIPT performance because they help you understand how accurate the test is and what the results mean. You might be wondering why it’s important to understand those “boring statistics” related to NIPT (non-invasive prenatal testing) performance, but trust us, it’s actually really helpful! Knowing these statistical terms can make a big difference in your pregnancy journey.

By understanding these terms, you can make informed choices about your prenatal care. If the test is really accurate, you might feel more confident in the results and decide not to have further tests. But if the test has limitations, you might want to consider additional testing to get more clarity. It’s all about making sure you have the information you need to make the best choices for you and your baby.

So, while statistics might seem boring at first, they play a vital role in your understanding of the test’s accuracy, interpretation of results, and decision-making process. Embracing these statistics can give you more confidence and peace of mind throughout your pregnancy journey.

Please see below the most important statistical terms related to NIPT performance:

  1. Sensitivity: This measures how good the test is at correctly identifying fetuses that have a chromosomal abnormality. A high sensitivity means that the test is good at detecting most cases of abnormality. For example, if a test has a sensitivity of 99%, it means that out of 100 fetuses with a chromosomal abnormality, the test correctly identifies 99 of them.
  2. Specificity: This measures how good the test is at correctly identifying fetuses that do not have a chromosomal abnormality. A high specificity means that the test avoids identifying normal fetuses as abnormal. For example, if a test has a specificity of 99%, it means that out of 100 normal fetuses, the test correctly identifies 99 of them as normal.
  3. Positive predictive value (PPV): This is the probability that a positive test result is a true positive. In other words, if the test comes back positive, the PPV measures the likelihood that the fetus actually has a chromosomal abnormality. For example, if a test has a PPV of 95%, it means that out of 100 positive test results, 95 of them are true positives.
  4. Negative predictive value (NPV): This is the probability that a negative test result is a true negative. In other words, if the test comes back negative, the NPV measures the likelihood that the fetus does not have a chromosomal abnormality. For example, if a test has an NPV of 99%, it means that out of 100 negative test results, 99 of them are true negatives.
  5. False positive rate (FPR): This measures how often the test gives a positive result for a normal fetus. A low FPR means the test is good at avoiding false positives. For example, if a test has an FPR of 1%, it means that out of 100 normal fetuses, the test gives a false positive result for only 1 of them.
  6. False negative rate (FNR): This measures how often the test gives a negative result for an abnormal fetus. A low FNR means the test is good at avoiding false negatives. For example, if a test has an FNR of 1%, it means that out of 100 fetuses with a chromosomal abnormality, the test gives a false negative result for only 1 of them.

When we look at how well NIPT works, it’s important to consider a bunch of statistics together. A good test will have high sensitivity, high specificity, low false positive and false negative rates, and high PPV and NPV.

Just remember, the performance of NIPT can vary depending on the specific test and the group of people being tested. So, when you get the results, make sure to understand how good that particular test is.

Considering all these statistics helps us know how reliable the test is and what the results mean for you and your baby. It’s about making informed choices and getting the best care possible.

Learn more about the NIPT providers we use:

Harmony Test by Roche: https://harmonytest.roche.com/global/en/home.html

Panorama Test by Natera: https://www.natera.com/womens-health/panorama-nipt-prenatal-screening/

PrenatalSAFE by Eurofins: https://www.eurofins.ie/biomnis/our-services/medical-testing/non-invasive-prenatal-test-nipt-prenatalsafe/

Unity Test by BillionToOne: https://unityscreen.com/

Pregnancy Testing – Deep Dive into the Beta HCG Test

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Pregnancy tests aim to provide a simple yet effective method of determining if you’re pregnant. There are two primary types of pregnancy tests available: urine tests and blood tests. While urine tests are more commonly used due to their convenience and over-the-counter availability, blood tests, specifically the Beta HCG (Human Chorionic Gonadotropin) test, offer a more detailed insight into the pregnancy. Here’s an in-depth look at the Beta HCG pregnancy test, how it differs from urine tests, its accuracy, uses, and how to interpret the results.

What is a Beta HCG Pregnancy Test?

A Beta HCG test is a blood test used to detect pregnancy. Human Chorionic Gonadotropin (HCG) is a hormone produced by the placenta after implantation. The beta subunit of HCG can be detected in the blood serum of expectant mothers approximately 11 days after conception; HCG can be detected in the urine 12-14 days after conception.

There are two types of HCG tests:

  1. Qualitative HCG test: This test simply detects the presence of HCG in the blood. It gives a “yes” or “no” answer to the question, “Are you pregnant?” Doctors often order this test to confirm pregnancy.
  2. Quantitative HCG test (Beta HCG): This test measures the specific level of HCG in the blood. It can detect even very low levels of HCG, making it a highly accurate test.

How Does a Beta HCG Test Differ from Urine Tests?

While both urine pregnancy tests and Beta HCG tests aim to detect the presence of HCG, there are distinct differences:

  1. Method of Testing: Urine tests can be done at home, while Beta HCG tests require a blood sample taken in a healthcare setting.
  2. Sensitivity: Beta HCG tests are more sensitive than urine tests and can detect lower levels of HCG. This means they can confirm pregnancy earlier than urine tests — typically around 11 days after conception.
  3. Information Provided: While urine tests only provide a positive or negative result, a Beta HCG test can provide more information about the pregnancy, like the approximate age of the fetus, or if there are potential complications.

The Accuracy of Beta HCG Pregnancy Test

Beta HCG tests are highly accurate. Because they can measure the exact amount of HCG in the blood, they can detect pregnancy earlier than urine tests, and they can also confirm or rule out potential problems.

However, while the Beta HCG test can detect if you’re pregnant, a single test can’t always accurately predict a healthy pregnancy. Levels of HCG can vary greatly among individuals, and a single measurement isn’t always indicative of a problem or complication. Doctors often will test HCG levels more than once, looking at how the levels change over time.

Uses of Beta HCG Pregnancy Test

Aside from confirming pregnancy, a Beta HCG test can be used for the following:

  1. Monitoring Pregnancy: Doctors may use Beta HCG tests to monitor the health of a pregnancy, particularly in the early weeks. They may use serial measurements to see if HCG levels are rising as they should.
  2. Identifying Ectopic Pregnancy: Lower than usual levels of HCG or levels that do not increase as they should may suggest an ectopic pregnancy — where the fertilized egg implants outside the uterus.
  3. Screening for Down’s Syndrome: As part of the “double,” “triple,” or “quadruple” screen test, the Beta HCG test can help assess a baby’s risk of Down syndrome.

Interpreting Beta HCG Test Results

Interpreting Beta HCG test results isn’t always straightforward, as normal HCG levels can vary widely. Typically, in a healthy pregnancy, HCG levels double approximately every 48 hours in the first weeks following conception.

However, unusually high or low levels, or levels that don’t increase as they should, might indicate a problem, such as an ectopic pregnancy, a miscarriage, or a potential chromosomal abnormality. In such cases, your healthcare provider will likely order further tests to determine the cause of the abnormal HCG levels.

It’s important to remember that while the Beta HCG test is a crucial tool in pregnancy monitoring, it is just one aspect of a larger picture. It should be used in conjunction with other tests and examinations to ensure a comprehensive understanding of both maternal and fetal health.

In conclusion, the Beta HCG pregnancy test is a sensitive, accurate, and versatile tool in the early detection and monitoring of pregnancy. By understanding its uses and how to interpret the results, you can gain a more comprehensive view of your pregnancy journey.

Here are typical ranges for hCG levels during pregnancy:

  • 3 weeks: 5 – 50 mIU/mL
  • 4 weeks: 5 – 426 mIU/mL
  • 5 weeks: 18 – 7,340 mIU/mL
  • 6 weeks: 1,080 – 56,500 mIU/mL
  • 7 – 8 weeks: 7,650 – 229,000 mIU/mL
  • 9 – 12 weeks: 25,700 – 288,000 mIU/mL
  • 13 – 16 weeks: 13,300 – 254,000 mIU/mL
  • 17 – 24 weeks: 4,060 – 165,400 mIU/mL
  • 25 – 40 weeks: 3,640 – 117,000 mIU/mL

Looking to book a blood test with us? Please visit our Blood Tests page. If you already had your pregnancy confirmed, we recommend to book an early pregnancy scan to check for the baby’s wellbeing.

The New Age of Prenatal Screening: An In-depth Look at Non-Invasive Prenatal Testing (NIPT)

Written by London Pregnancy Clinic on . Posted in Blog, NIPT, NIPT, Obstetrics, Ultrasound. No Comments on The New Age of Prenatal Screening: An In-depth Look at Non-Invasive Prenatal Testing (NIPT)

Pregnancy, while a joyous period in life, is also a time filled with uncertainties. One significant concern for expectant parents is the health of their unborn child. Fortunately, modern-day medical advancements, such as Non-Invasive Prenatal Testing (NIPT), are here to provide some peace of mind.

This article explores NIPT’s accuracy, introduces other prenatal screening options, highlights key NIPT providers, discusses its limitations and benefits, and explains instances where NIPT may not be suitable.

Unveiling Non-Invasive Prenatal Testing (NIPT)

NIPT is a revolutionary screening test that leverages advanced technology to detect the risk of specific genetic disorders in the unborn child using a simple maternal blood draw. Common conditions screened through NIPT include Down Syndrome (Trisomy 21), Edwards Syndrome (Trisomy 18), and Patau Syndrome (Trisomy 13). The screening can be performed as early as the 10th week of pregnancy.

Delving into NIPT’s Accuracy

When it comes to screening accuracy, NIPT outshines other prenatal screening tests. Its sensitivity and specificity for detecting Trisomy 21 exceed 99% and 99.9%, respectively. For Trisomy 18, the sensitivity and specificity approximate 97-99% and nearly 100%. For Trisomy 13, the sensitivity is between 90-96%, and the specificity again nears 100%.

However, it is paramount to understand that NIPT is a screening test, not a diagnostic tool. It can indicate the potential of a genetic disorder, but it cannot definitively diagnose the condition. A positive NIPT result suggests a higher risk, warranting further diagnostic tests like amniocentesis or chorionic villus sampling (CVS) for confirmation.

Exploring Other Prenatal Screening Options

NIPT isn’t the only prenatal screening available to expectant parents. Other alternatives include:

  1. First-trimester combined screening: This screening comprises a maternal blood test and an ultrasound examination. Although it can detect about 85% of Down Syndrome cases, it does carry a higher false-positive rate compared to NIPT.
  2. Quad screen: This blood test is capable of detecting around 81% of Down Syndrome cases in women under 35.
  3. Cell-free DNA screening (cfDNA): Technically similar to NIPT, this screening method has a high level of accuracy and is typically reserved for pregnancies considered high-risk due to the associated cost.

Introducing Key NIPT Providers

Several leading companies globally offer NIPT services:

  1. Eurofins (PrenatalSafe Test): A globally recognized leader in the field of genetic testing, Eurofins offers comprehensive NIPT services.
  2. Natera (Panorama Prenatal Screen): Natera stands out for its ability to perform tests as early as the 9th week of pregnancy.
  3. Roche (Harmony Prenatal Test): Pioneers in the NIPT field, Roche’s Harmony test is widely available, being offered in more than 100 countries.
  4. BillionToOne (Unity Prenatal Test): A more recent entrant into the NIPT field, offering a more cost effective test with promising clinical data.

Each provider has unique strengths, and choosing the right one depends on several factors, including your doctor’s recommendation, the test’s availability in your area, and insurance coverage.

Weighing the Limitations and Benefits of NIPT

Like all medical procedures, NIPT has its pros and cons.

Benefits of NIPT:

  • Non-invasive: NIPT requires only a maternal blood draw, posing zero risk to the fetus.
  • Early and accurate risk assessment: Compared to traditional screening methods, NIPT provides an earlier and more precise risk evaluation for certain genetic conditions.
  • Fewer invasive procedures: With its high level of accuracy, NIPT reduces the need for invasive diagnostic procedures, which carry a risk of miscarriage.

Limitations of NIPT:

  • Screening, not diagnosis: NIPT isn’t a diagnostic test; thus, a positive result warrants confirmation with further invasive testing.
  • Limited screening scope: NIPT can’t screen for all genetic and chromosomal abnormalities.
  • Not suitable for screening physical/structural anomalies which are often more prevalent and severe.
  • Possible inconclusive results: There can be instances where NIPT results are inconclusive, necessitating a retest.

NIPT Exclusions: When is NIPT Not Suitable?

Despite its many advantages, NIPT isn’t for everyone. Certain situations can limit its effectiveness, depending on the provider of the test and their algorithm. These can be, but not limited to:

  • Pregnancies involving more than two fetuses (triplets or more).
  • When the expectant mother has a history of bone marrow or organ transplant.
  • Pregnancies resulting from a donor egg.
  • Vanishing twin pregnancies.

In such situations, a detailed discussion with the healthcare provider will help in determining the best approach for prenatal screening.

In conclusion, NIPT brings a significant shift in prenatal screening with its high accuracy rate and non-invasive nature, contributing immensely to maternal and child health care. However, it’s essential for expectant parents to discuss all options with their healthcare provider and make an informed decision. The understanding that no test is perfect and that screening tests have limitations is crucial to setting appropriate expectations.

Your health and that of your baby are of the utmost importance. An open dialogue with your healthcare provider will be the best approach to address your concerns and make an informed decision about prenatal screening.

Your Fertility Scan Guide 

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Endometrial Lining Scan 

Endometrial Lining Scan, also known as the ‘Baseline Scan’, is designed to assess the thickness of the womb as well as its general outline and structure. 

These scans are popular amongst patients going through IVF treatment and are designed to guide your referring clinician, helping them to understand and plan your treatment accordingly. This is done by estimating the best time and chances for conception in addition to preparation prior to embryo transfer. Book here.

London Pregnancy Clinic offer three price packages for Endometrial Lining Scans: 

  • Endometrial Lining Scan/Baseline Scan – £120 
  • One lining ultrasound scan 
  • Rose Package – £220 
  • Two lining ultrasound scans 
  • Lily Package – £320 
  • Three lining ultrasound scans 

Follicular Tracking Scan 

Follicular Tracking Scan, also known as Antral Follicle Count, assesses the total number and size of the follicles in each ovary. 

These scans are popular amongst those going through IVF treatment. Follicle Tracking Scan helps your referring clinician to make important decisions in your fertility treatment and as such it is imperative to get accurate readings. Book now.

Similar to Endometrial Lining Scan, we offer three price packages for Follicular Tracking Scans: 

  • Follicle Tracking Scan/Antral Follicle Count: £150 
  • One follicle tracking ultrasound scan 
  • Rose Package – £270 
  • Two follicle tracking ultrasound scans 
  • Lily Package – £390 
  • Three follicle tracking ultrasound scans 

HyCoSy Scan 

This is an advanced ultrasound scan to examine the fallopian tubes, uterus and ovaries providing an important insight into your fertility. 

HyCosy scans are performed by our expert Consultant Gynaecologist, Mr Prashant Purohit, specialises in reproductive medicine and fertility assessment. HyCoSy scans are recommended for patients who have experienced difficulties in getting pregnant. Book now.

  • Cost: £500 including a pre-procedure consultation 

Blood Test Services 

London Pregnancy Clinic offers a variety of different blood tests with a short turnaround time. The results will be sent to you and your referring consultant through our secure online system. 

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Pre Eclampsia

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What is Pre-Eclampsia? 

Pre-eclampsia is a hypertensive disorder. It is characterised by persistent high blood pressure that develops during pregnancy (usually from 20 weeks) or postpartum period (up to 6 weeks postpartum). 

With careful management, most pregnancies with pre-eclampsia will have good outcomes, but complications include problems with the growth of the baby, kidney and liver damage. 

Key Stats 

  • Hypertensive disorders of pregnancy (HPD) affects 5-10% all pregnancies worldwide. This includes pre-eclampsia, eclampsia, HELLP syndrome (haemolysis, elevated liver enzymes, low platelets) and gestational hypertension. 
  • HPDs are the leading cause of maternal and infant death across the globe. 
  • Approximately 76,000 women and 500,000 babies die each year worldwide from pre-eclampsia. 
  • Black women are 3x more likely to develop pre-eclampsia and have severe outcomes. 
  • 60% of maternal deaths due to pre-eclampsia are preventable. 

Symptoms 

  • Severe headaches 
  • Welling in hands and face 
  • Visual issues 
  • Nausea and vomiting 
  • Stomach or abdomen pain 
  • Sudden weight gain 
  • Shortness of breath 

Management 

Pre-eclampsia can develop from 20 weeks of pregnancy and up to 6 weeks after childbirth. High blood pressure can usually be controlled by antihypertensive medication. The risk of pre-eclampsia in pregnancy can be reduced by maintaining a healthy lifestyle.  

Please note that all these may help decrease rates of pre-eclampsia but should be consulted with a healthcare professional prior to action. 

What We Offer? 

Our Consultant Obstetrician, Mr Daniel Stott, specialises in the management of pregnancies affected by pre-eclampsia. He helps provide mothers with post-natal care and can address any concerns mothers have during or post pregnancy. Learn more about out Private Obstetric Services on the dedicated page. 

He also runs a pre-eclampsia clinic at his NHS post at University College London Hospitals NHS Foundation Trust. Mr Stott has published an MD on haemodynamics in hypertensive pregnancies at King’s College London and has published widely in pre-eclampsia. 

Awareness 

We want to do our part in raising awareness and supportive ongoing research to #MoveResearchForward. Let’s work together to help prevent pre-eclampsia and improve outcomes for mothers and babies worldwide. 

If you require any more information on pre-eclampsia, please check out the Pre-Eclampsia Foundation. 

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Meet The Team

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As we are a small, close-knit team you will become accustomed to seeing a few familiar faces whenever you enter the clinic, so here’s a bit more about us.

Dr Ushakov is our Founder and Medical Director. A leading expert in the field, with over 30 years’ experience in Fetal Medicine, working in three different countries. Dr Ushakov is most likely the reason you have booked your appointment with us and his patient, individual approach to each and every scan will provide you with calming reassurance.

Alcinda is our clinical assistant and her kind, calm nature will put you instantly at ease throughout your appointment. Alcinda is also trained in phlebotomy so you may also experience her excellent bedside manner during your NIPT blood test.

If you have an email or telephone enquiry you will most likely speak to our medical secretary, Ella. She is on hand to answer any questions you may have throughout your time with us. You may recognise her from the warm welcome you receive when you first enter the clinic.

How big is the Embryo at 8 weeks?

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Most pregnancy apps will make you aware of the size comparison of your baby against a fruit/ vegetable/ animal or even baked goods, but rarely do you see images showing just how your baby would fit into the palm of your hand!

Take a look at this image which shows you the real size of your baby at 8 weeks!

At 8 weeks Dr Ushakov will be able to check for the heartbeat, date the pregnancy, check for single/multiple pregnancies. He will also check the structures of the pregnancy at this stage including the gestational sac, yolk sac and placenta.

During the Viability scan you will find out the estimated due date (Which will give you plenty of time to pack up that hospital bag and plan out your babymoon)!

If you are interested in having the viability scan at City Ultrasound, you can book our scans or give us a call on 02036872939 for more information

Clinic Video Tour

Written by London Pregnancy Clinic on . Posted in Blog.

City Ultrasound is a pregnancy care centre based in the City of London in close proximity to Spitalfields Market. We specialise in the early diagnosis of congenital anomalies, and have more than 30 years of expertise in fetal medicine. Our clinic is equiped with the latest ultrasound equipment with the latest 3D/4D technology to produce outstanding quality of imaging for diagnostic purposes.

Our clinic has been recently refurbished to provide a relaxing environment for our patients who come in for early pregnancy reassurance. Watch this short Video Tour introducing our clinic and our staff!

https://www.youtube.com/watch?v=is1rESozCZc

Spina Bifida

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Some media coverage of UCLH Spina Bifida unit on the BBC. Dr Fred Ushakov is a proud member of this clinic screening dozens of Spina Bifida cases a year from all over the UK. At City Ultrasound we screen for Spina Bifida from 10 weeks of pregnancy in our first trimester anomaly scan, also known as the Early Fetal Scan.

What is Spina Bifida?

Spina Bifida is a neural tube defect affecting the development of the spine and spinal cord of the baby. The neural tube is an embryonic structure that ends up forming the baby’s brain and spinal cord. There are three types of Spina Bifida; occulta, meningocele and myelomeningocele. Occulta (Latin for ‘hidden’) is the mildest form of Spina Bifida with symptoms including a hairy patch on the back or a dark spot on the back.

Myelomeningocele is the most severe anomaly and is commonly referred to as ‘open Spina Bifida’. The spinal canal remains open along several vertebrae in the back and exposing the baby’s tissues and nerves and forming a sac. Open Spina Bifida is associated with many other medical issues and is potentially life threatening for the baby. Some of the common complications associated with this type are: walking problems, orthopaedic issues, bowel issues, latex allergy, dermatological problems and accumulation of fluid in the brain.

According to the FMF, at 12 weeks the prevalence of Open Spina Bifida is 1 in 1,000 fetuses. In reality we believe that the condition is less prevalent in the UK but is still one of the most common neural tube defects. At City Ultrasound we screen for Spina Bifida from 10 weeks in our Early Fetal Scan.

Some of the risk factors for Spina Bifida include; folate deficiency (read our blog post on the Folic Acid), genetic history if neural tube defects, diabetes, certain medications and obesity.

Choosing Your Scan

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Choosing Your Scan ?

It can feel a difficult decision knowing when to book in for your ultrasound scans, but truth be told there is no right or wrong time. Whether you are seeking general reassurance, a comprehensive check of your baby’s structures or an NIPT we have scans to suit your individual needs. Your baby is developing at such a pace and week by week there is visible growth. We offer scans for each and every stage of your baby’s development so you can feel assured at every step of the way.
For the best diagnostic performance, we have created a comprehensive breakdown of our scanning options and the prime time to have them done:

?6-9 weeks – Viability Scan

?10-16 weeks – Early Fetal Scan

?20-23 weeks – Anomaly Scan

?28- 34 weeks – Baby development Scan

?36-40 weeks – Baby Position Scan

?8-40 weeks – Scan Upon Request

To find out more details regarding the above scans please check out our website which has a breakdown of everything included in each scan.