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First Trimester Combined Test And Integrated Tests

For Screening

For Down Syndrome And Trisomy 18

THANK YOU

Screen Positive First Trimester Combined Test Results

Counselling Issues

Inform

Diagnostic And Management Options

The Natural History Of Down Syndrome

Enable The Parents

To Balance

Risks, Limitations, And Benefits Of Prenatal Screening And Diagnostic Testing

With

Medical, Educational And Social Issues Involved In Raising A Child With Down Syndrome Or

Pregnancy Termination

If CVS Is Unavailable

Do Not Offer First Trimester Combined And Stepwise Sequential Testing

Women With Positive Screening Results

Offer Definitive Fetal Karyotype Determination By CVS

Alternative

Secondary Screening Using A Maternal Plasma-Based Test For Cell-Free Fetal DNA

Screen Positive Integrated Test Results

Screen Negative First Trimester Or Integrated Test Results

The Cut-Off Often Higher Than That Of The Combined Or Quadruple Test

Typical Cut-Off : A Midpregnancy Risk Of Down Syndrome Of ≥1 In 100

A FPR Of 1 To 2 % And Odds Of Down Syndrome Of About 1 In 5 To 1 In 10.

Amniocentesis Is The Diagnostic Test

Patient's Risk Of Having A Baby With Down Syndrome

Is Less Than

A Specified Cut-Off Level

Meaning

Patient's Risk Provided In The Report (Eg, Down Syndrome Risk 1 In 900)

This Number Should Be Given To The Patient

Does Not Exclude The Possibility Of Down Syndrome

No Further Testing Is Recommended

Detection Of Structural Anomalies

??

Does It Obviate The Need For Second Trimester Fetal Assessment

Including

Second Trimester USG Examination Or AFP Screening For NTD

TRISOMY 18 RISK ASSESSMENT

Prevalence Is Three To Five-Fold Higher In The First And Second Trimesters

About 1 In 8000 Births

90 % Of Affected Infants Die Within The First Year Of Life

50 % Die Within The First Week

TRISOMY 18 RISK ASSESSMENT

First Trimester Analyte Pattern Characteristic

Very Low Beta-Hcg And Very Low PAPP-A, And Increased NT Measurement

FPR Kept Very Low (Less Than 0.5 Percent)

So That

Only A Small Number Of Very High Risk Women

Will Be Offered Invasive Diagnostic Testing

Integrated Test

Highly Efficient In Identifying Cases Of Trisomy 18

DR 90 % At FPR Of 0.1 Percent

OTHER ANEUPLOIDIES

Screening For Such Defects Is Not Warranted --- Low Prevalence

Many Of These Defects Are Either Lethal

Fetus Is Often Lost Early In Pregnancy

Or

Mild

Risk Of Invasive Testing Is Questionable

First Trimester Combined Screening

DR 78 % Of All Non-Down Syndrome Aneuploidies, With FPR Of 6 %

OTHER ANEUPLOIDIES

Identified

As

Being At High Risk For Down Syndrome Or Trisomy 18,

Or

Presented With Cystic Hygroma In The First Trimester

ADVERSE PREGNANCY OUTCOME

Predictive Of Obstetrical Complications

But

The Predictive Value Of These Tests Is Low

VARIABLES THAT AFFECT PERFORMANCE AND INTERPRETATION

Selection of Risk Cut-off

Midpregnancy Versus Term Risk

Effect of Maternal Age

Prior Pregnancy History

Method Of Gestational Age Determination

Adjustments To MoM

• Race

• Body Weight

• Multiple gestation

• Diabetes mellitus

• In vitro fertilization

• Previous false positive result

• Smoking

MANAGEMENT

Screen Positive First Trimester Combined Test Results

Refers To

Risk Of Having Child With Down Syndrome = Or > A Specific Cut-Off Level

Typical Cut-Off

Term Risk Of Down Syndrome Of ≥1 In 300

Associated With

FPR Of About 5 % And Odds Of Down Syndrome Of About 1 In 20

MANAGEMENT

Findings Which Warrants Immediate Diagnostic Work-Up

Septated Cystic Hygroma :: 50 % Risk Of Aneuploidy

Nuchal Translucency ≥3 Mm :: 17 % Risk Of Aneuploidy

Also Associated With Other

Structural Malformations

FIRST TRIMESTER COMBINED TEST

DUAL MARKER

0/7ths

6/7ths

9 And 13 Weeks Of Gestation

Obvious Advantages

Maximum Time For Decision Making

Privacy

Safer Methods Of Pregnancy Termination

FIRST TRIMESTER COMBINED TEST

DUAL MARKER

• Maternal Serum Beta-Hcg

• Maternal Serum PAPP-A

• Ultrasound Measurement Of Nuchal Translucency (NT)

+

• Maternal Age

INTEGRATED TESTS

Testing Uses Markers Measured In Both First And Second Trimesters

A Single Risk For Down Syndrome Calculated

PAPP-A

Between 9 And 13 Weeks

Provide A Patient-Specific Risk

Between 10 And 13 Weeks

USG Measurement Of NT + Estimation Of GA By CRL

Second Trimester

Quadruple Test Markers AFP,Ue3, Inhibin A, Beta-Hcg)

Six Marker Values Are Used Together With Maternal Age

INTEGRATED TESTS

Down Syndrome

DR 85 % FPR 5 %

An 85 % DR At A 1 % FPR

If A 90 % DR Is The Target, The FPR Will Be 2 %

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Advantage

Substantially Lower FPR Than Combined Or Quadruple Test

Decrease No Of Patients Who Are Anxious

DR 91 % FPR 1 %

Fewer Procedure-Related Miscarriages

Trisomy 18

Also Detects Trisomy 18

Disadvantage

Serum Integrated Test

Full Integrated Test, But Without USG Measurement Of NT

Step-Wise Sequential Screening

First Trimester Portion Of The Integrated Screen

Women At Very High Risk (Eg, 1 In 50) CVS

OTHER : Complete The Second Trimester Portion Of The Test

DR 95 % With FPR Of 5 % ( Downs )

Combined Test Slightly Better Than Second Trimester Quadruple Test

Benefit Of Availability Of Early Results For Highest Risk Patients

Contingent Sequential Screening

Women At Very High Risk (Eg, >1 In 50) After First Trimester Testing

OFFER : Immediate Invasive Prenatal Diagnosis

Women At Low Risk (Eg, <1 In 2000) After First Trimester Testing Provide : With Their Risk Estimate -- No Any Additional Testing

FIRST TRIMESTER COMBINED TEST

Women At Intermediate Risk ( Between 1 In 50 And 1 In 2000) Second Trimester Blood Draw To Complete The Integrated Test

A Cost-Effective Approach

No Consensus On Thresholds

COMPARATIVE DATA FROM PROSPECTIVE TRIALS

The Serum, Urine And Ultrasound Screening Study (SURUSS)

And

First And Second Trimester Evaluation Of Risk (FASTER) Trial

Full Integrated Test

The Most Efficient Screening Test (High DR, Low FPR)

Procedure-Related Unaffected Fetal Loss : 9 Per 100,000 Women Screened V/S

Combined Test Or A Second Trimester Quadruple Test : 45 Per 100,000

If NT Testing Is Not Available :: Next Most Efficient Choice

Serum Integrated Test

Quadruple Test :: The Best Available Option

For Women Who Present For Prenatal Care In Second Trimester

FIRST TRIMESTER COMBINED TEST

First Trimester Combined Screening

Reasonable Approach Who Desire Earliest Possible Screening And Diagnosis

Stepwise Sequential Screening - A Variant Of The Integrated Test

A Valuable Alternative

Reports Very High Risk Results In The First Trimester

Timing Of Blood Sample And Ultrasound

6/7ths

0/7ths

Between 11 And 13 Weeks Of Gestation

Elevated In Pregnancies Affected With Down Syndrome

Beta-HCG

Free Beta-Hcg

Total Beta-Hcg

Lower In Pregnancies Affected With Fetal Down Syndrome

PAPP-A

Operator Expertise And Quality Of Equipment

Nuchal Translucency

Proper Training And Ongoing Quality Management

Inhibin A

BASIC APPROACH TO COUNSELING

• Explanation Of Difference Between Screening Test And Diagnostic Test

• Screening Sensitivity And Specificity Compared To Diagnostic Testing

• Description Of Performance Of Various Screening Tests

• Option Of Diagnostic Testing Instead Of Screening

• Risks Associated With Prenatal Diagnosis

• Psychological Implications Of Prenatal Screening And Diagnosis

• Implications Of Having A Child With Down Syndrome

• Detection Rate Of Other Chromosomal Abnormalities And Implications Of Having Child

• Information About Length Of Time Necessary To Obtain Results From Screening And

• Information About Pregnancy Termination.

Diagnostic Testing

Dual Marker

Findings Which Warrants Immediate Diagnostic Work-Up

• Nuchal Translucency ≥3 mm :: 17 % Risk Of Aneuploidy

• Septated Cystic Hygroma :: 50 % Risk Of Aneuploidy

Also Associated With Other

Structural Malformations

• A previous pregnancy complicated by fetal trisomy

• At least one major or two minor fetal structural anomalies in

the current pregnancy

• Chromosomal translocation, inversion, or aneuploidy in Patient

or Partner

Dr Rajiv Gokhale

M.D. ( Ob Gyn )

Fellow ( Gyn Onco )

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