# Presentation: 079886

## Prenatal Testing Update 2007	

- George J. Gilson, M.D.
- Alaska Native Medical Center

## PRENATAL TESTINGBENEFITS

- optimize the place of birth and early therapy of the child
- giving women information and choice about their pregnancy
- burden of disease (20% of pediatric admissions for congenital problems)

## PRENATAL TESTINGCOUNSELING

- Informational
- Nondirective
- Supportive

## PRENATAL SCREENINGBASICS

- Every woman has a 3-4% chance of having a child with a birth defect, 1% of which may be life-threatening

-  The most common are:
- 	-Down syndrome (1/700 live births)
- 	-Neural tube defects (1-2/1000 “  “)
- 	-Cystic fibrosis (1/3300 in Caucasians)

## UPDATED BASIC CONCEPTS ABOUT PRENATAL SCREENING

- Women >35 y/o have only 20% of the infants with Down syndrome
- Prenatal DS screening should be offered to _all_ pregnant women
- Maternal age is a very insensitive marker for fetal aneuploidy
- Women of any age may choose or decline invasive testing for fetal DS

## Slide 6

## PRENATAL SCREENING:CURRENT TIMING

** ****Nuchal**** ****translucency & PAPP-A/free bHCG**

**11+1 – 13+6 weeks**

** ****Quad screen & anatomic survey**

**15 – 20 weeks**

## PRENATAL SCREENING“MYTHS”

- Prenatal testing promotes abortion
- Prenatal testing seeks to eliminate genetic disease
- Amniocentesis is a risky procedure
- All pregnant women over age 35 need to undergo amniocentesis

## Figure 1.  Number of invasive prenatal tests, increase in the number of advanced maternal age women in the population, and the number expected to be screen-positive by serum screening (triple test) by year.

**Figure 1.  Number of invasive prenatal tests, increase in the number of advanced maternal age women in the population, and the number expected to be screen-positive by serum screening (triple test) by year.**
**Diamonds=invasive tests; **_**triangles=serum screen-positive**_**; squares=advanced maternal age**

***Benn. Prenatal Diagnosis Utilization. Obstet Gynecol 2004***

## PRENATAL SCREENING

- “Offering routine amniocentesis to women >35 y/o without first performing maternal serum screening (and/or U/S) is an anachronism that should be abandoned”
- Egan, OG 2000; 96:979-85.

## Slide 11

## PRENATAL TESTING:2nd  TRIMESTER

-  **QUAD SCREEN **
**+**
**COMPREHENSIVE ULTRASOUND**

## CASE #1

- 19 y/o G1P0 at 16 weeks by her dates has a QS (+) for NTD with a risk of 1:85:
- AFP - 2.77 MoM
- What are the next most appropriate steps?

## Quad Screen (+) NTDCOUNSELING

- emphasize “screening”, not “pass-fail”
- MSAFP detects 65% (80%) of NTD
- FPR = 5%
- only 1 in 50 women with a (+)TMS will have a fetus with a NTD
- age, race, weight, DM, GA all key
- US is critical for dating

## ELEVATED MSAFPCAUSES

- Wrong dates
- Twins
- IUFD
- Abdominal wall defects
- Vaginal bleeding
- “non-specific”
- NTD

## AFP (+) NTDULTRASOUND

- If LMP >7-10 days off from US, use US
- If GA by US <15 wks, repeat at the appropriate time (15-20 wks)
- If GA by US >GA by LMP, have the lab recalculate the screen
- If AFP between 2.0-3.0 MoM, repeat the AFP

## AFP (+) NTDULTRASOUND II

- HRUS should identify 96% of NTD
- amniocentesis usually not indicated
- if no cause found, there is still a 1-2% risk of later adverse event (e.g., FGR, IUFD, PIH, PTL, etc.)
- consider f/u growth scan at 28 wks

## Slide 18

## CASE #2

- 25 y/o G3P1 at 16 weeks by her dates has a MMS which returns positive for fetal DS with a risk of 1:131
- What are the most appropriate next steps?

## 2nd Trimester Multiple Marker Screening for Fetal Down Syndrome 

- Triple screen:  AFP, estriol (UE3), HCG
- Quad test: AFP, UE3, HCG, Inhibin-A
- Cut-off: 1:270 (risk for 35 y/o)

## Quad screen for detection of fetal aneuploidy

- _  __T-21_				_T-18_
- Low AFP                       Low AFP
- Low estriol                     Low estriol
- Elevated HCG		 Low HCG
- Elevated inhibin		 Normal inhibin

## MMS (+) DSCOUNSELING

-                            _Sensitivity_	 _FPR_
**Triple**	(<35yo) 	65%		  5%
-     		(>35yo) 	80%		20%
**Quad**	(<35yo)	78%		  5%
-     		(>35yo)	85%		11%

## MMS (+) DSULTRASOUND

- if LMP differs>7-10 days from US, use US dating
- if necessary, have lab recalculate values for the corrected gestational age
- if LMP = US, do _**NOT**_ repeat MMS
- HRUS for “soft markers” of DS

## Slide 24

## Slide 25

## Slide 26

## Slide 27

## Slide 28

## MMS (+) DSUS “SOFT MARKERS”

- originally described in high risk populations
- may be found in up to 15% of normal fetuses
- low sensitivity and PPV
- >1 marker increases likelihood
- a normal scan may reduce likelihood of DS by up to 60%

## TMS (+) DSUS “SOFT MARKERS”

- 		_**MARKER**_        			_**LR**_
- major anomaly            		25
- nuchal fold thickening  		19
- echogenic bowel  			  5.5
- short femur/humerus 		  2.2
- pyelectasis, EIF, CPC 	         ~1.5

## U/S SOFT MARKERS for DSMeta-analysis – 2001

- n=130,365 pregnancies (1,930 w/DS)
- 	                 _Sens_   _Spec_   _PPV _ _(HR/LR)_
- NF		   	  4	99	   5.0      2.0
- Short FL	16    96       0.4      0.9
- Echo bowel  	  4    99       2.0      0.9
- EIF               	11    96       0.4      0.9
- Multiple        	69    92       0.2      0.3

## MMS (+) DSAMNIOCENTESIS

- 1 in 200 risk of pregnancy loss
- ~1 case of DS detected for every 40 amnios with current strategy
- 99.5% accuracy for fetal karyotype
- 7-10 day turnaround time
- FISH for rapid answer (48 hours)

## CASE #3

- 42 y/o G6P5 at 16 weeks by her dates declines amniocentesis but wishes to have QS and HRUS.
- Is this an appropriate strategy for her?

## Slide 34

## 1st  TRIMESTER SCREENING

**SERUM SCREENING**
** ****+**
**NUCHAL TRANSLUCENCY**

## She doesn’t want to wait....

*She** doesn’t want to wait....*

## 1st  TRIMESTER TESTINGADVANTAGES/DISADVANTAGES

_**Positive:**_
- earlier answer
- more time for discussion and options
_**Negative:**_
- testing will find abnormalities that would have been spontaneously lost
- testing is only for aneuploidy, not NTD
- implementation issues

## 1st  TRIMESTER SCREENCOMBINED TEST

- US: fetal nuchal translucency
- Labs: free bHCG + PAPP-A
- Testing done at 11w+1d to 13w+6d

## 1st trimester screening for fetal aneuploidy

-   _T-21_				_T-18_
- Elevated free bHCG	low free bHCG
- Low PAPP-A			low PAPP-A
- Thickened NT		Thickened NT

## Slide 40

## 1st TRIMESTER SCREENING

- _Detection Efficiency for DS (5% FP rate)_
- NT alone                              69%
- Free B-hCG + PAPP-A        63%
- NT + serum markers            89%

## 1st  TRIMESTER SCREENImportance of QI

- -NT measurement critically dependent on training and ongoing QI
- -certification available from FMF (UK) and SMFM (US)
- -take 1-d course, take test, collect cases, submit images for critique, have 10 images accepted; repeat q12 mos

## Slide 43

## Follow up 1st Trimester ScreeningDIAGNOSTIC PROCEDURES

- chorionic villus sampling (10-13 wks)
- early amniocentesis (12-13 wks)
- wait for later amniocentesis (>15 wks)

## Increased NT – normal karyotype: Other associations

- _NT>3.5 mm (>99__th__ percentile)_
- Cardiac defects				3-7%
- Other anomalies/syndromes		10%
- Fetal death					  3%
- Normal outcome				70%
- _PLAN:_ Detailed anatomy/fetal echo in the 2nd trimester
- Souka AP - AJOG 2005

## 1st Trimester ScreeningLIMITATIONS

- limited visualization of fetal anatomy
- ONTD screen must wait until 2nd trim
- placental mosaicism w/ CVS (1-2%)
- loss rate after CVS (2.6%)
- early amnio (12-14 wks) associated w/ increased loss rate (2-3% vs. 0.5%)

## 	1st Trimester Screening		LIMITATIONS

- only 6% of MFM perform CVS
- women may not present early enough for 1st trimester screening
- women may not return for the 2nd trimester testing
- not all labs are capable of integrating 1st and 2nd trimester results

## 1st  TRIMESTER SCREENCURRENT STUDIES - 2007

- _STUDY_		_N_	_DS_	_DETECTION(%)_
- BUN		 8,216		 61		79
- SURUSS* 	33,557	 84		83
- FASTER* 	47,053	101		83
- OSCAR	15,030	 82		90
- * (“integrated” testing strategy)

## Strategies for putting 1st & 2nd trimester results together

- Fully integrated (NT, PAPP-A, QS)
- Serum integrated (PAPP-A, QS)
- Stepwise sequential
- Contingent sequential

## Putting 1st & 2nd trim together: “STEPWISE SEQUENTIAL”

- 1st trim (+): dx test offered
- 1st trim  (-): 2nd trim test offered
- Final: 1st and 2nd trim results integrated
- Detection: 95% w/ 5% FPR
- Lab must be able to integrate results!
- Malone F, et al. FASTER Trial.                   NEJM 2005; 353:2001-11.

## Putting 1st & 2nd trim together:“CONTINGENT SEQUENTIAL”	

- 1st trim (+): dx test offered
- 1st trim (-): no further testing
- 1st trim (intermed):2nd trim test offered
- 85% of pts finalized in 1st trim
- 93% detection at a 5% FPR
-   Cuckle H, et al. Semin Perinatol 2005; 29:252-7.

## OSCAR: “One Stop Clinic for Assessment of Risk”

-  -NT, PAPP-A, free bHCG at 11-13 wks
- 5.2% at increased risk -CVS offered
- 10.5%>14 wks -QS + US for markers
- 6.1% at increased risk -amnio offered
- 96% detection w/ FPR 5.2%
- Spencer, BJOG 2003; 110:281-6.

## SCREENING STRATEGIES:SUMMARY

- _STRATEGY__	_		_DETECTION(%)_
- Triple screen			69
- Quad screen			81
- 1st trim screen		85
- Integrated screen		95
- Serum integrated		86
- Sequential screen		94

## Should your practice offer it?Is FASTER better??

- Can you refer for NT, or can you, or your sonographers, become certified?
- Can you maintain on-going QA for NT?
- Can your lab integrate 1st + 2nd results?
- Is referral for CVS available?
- Will patients present early enough?

## What is the best implementation strategy for rural practice?

- If referral for US is difficult, the “serum integrated test” may be the best strategy.
- 1st trimester serum (+): refer for NT and CVS immediately if patient wishes....or:
- wait for 2nd trimester serum:  refer for 2nd trimester US and/or amnio
**population screening issues **
**vs**
**individual women’s issues**

## PRENATAL SCREENINGWHAT DO WOMEN WANT?

- _Kornman. Prenat Diagn 1997; 17:1011_
- 76% of low-risk women who had 2nd               trimester screening would have preferred 1st trimester screening, if available.
- 44% of high-risk women would not have had CVS had 1st trimester noninvasive testing been available.

## PRENATAL SCREENING:What do women want?

- _Mulvey. Prenat Diagn 2003; 23:828_
- 75% of those <37 y/o prefer lower FPR
- 64% of those _>_37 y/o prefer highest possible detection rate
- Different screening options for different women (and different cultures....)
- What does YOUR patient choose??

## Prenatal TestingWhat do women want?

- _Nicolaides- AJOG 2005; 193:322_
- n=30,564  (48%>35 y/o)
- 8.4% 	high risk78% had amnio/CVS
- 91.6%   low risk  4.6%   “       “	     “
- Most women used the info appropriately to decide on whether or not to have invasive testing

## PRENATAL SCREENING: WHAT DO WOMEN WANT?

- 	-_Muller. AJOG 2007; 196:315_
- 					_2000__	_	_2005_
- 2nd trim screen		75%		25%
- 1st  trim screen		0.8%		49%
- aneuploidy detect	70%		83%
- invasive test/case	32		15
- -_conclusion_: women’s confidence in 1st trim testing results in less invasive testing

## SCREENING FOR DS: WHAT ARE THE COSTS?

- Economic cost (lab, U/S, invasive tests)
- Lifetime cost caring for DS children
- “Hidden cost” (your time counseling)
- Cost of miscarriage after invasive tests
- False positives and the emotional cost to parents

## SCREENING FOR DS:DECISIONS BASED ON VALUES

- Maximal information
- Earliest possible diagnosis -_vs_.-
- Minimal risk to the pregnancy
- Reassurance about fetal health
- Parents’ values always come first:      the real meaning of “choice”

## PRENATAL SCREENING FOR COUPLES WHO WOULD NOT CONSIDER ABORTION

- The odds invariably favor a normal outcome
- Anomaly detection may allow neonatal intervention/benefit
- Parents may chose to avoid cesarean delivery for fetal indications
- Opportunity to prepare themselves emotionally and financially

## 1st Trimester ScreeningACOG Position (1999)

- NT measurements are CRL dependent
- NT measurements are operator dependent
- fetal lymphedema may screen for fetal cardiac anomalies as well
- “promising but investigational”
- “not recommended for routine clinical use at this time”

## 1st Trimester ScreeningACOG Position (July 2004)

- 1st trimester screening is an option if:
- appropriate US training and ongoing QI
- comprehensive counseling available regarding options and limitations
- access to appropriate diagnostic test if results are positive

## 1st Trimester Screening: ACOG Recommendations - (2007)

- DS screening is an option that should be offered to all women, regardless of maternal age, but it is not routine
- 1st trimester screening is an effective option for all women
- Women should be offered the option of invasive testing if found to be at increased risk
- NT measurement requires special training and ongoing QI
- ONTD screening should be offered in the 2nd trimester

## Ultrasound image of absent nasal bone (no echogenic line below skin).

**Ultrasound image of absent nasal bone (no echogenic line below skin).**

**Ultrasound image of present nasal bone with echogenic line below skin.**

- Orlandi, F., et al, American J. of Obstet. & Gyn., 2005, 192, 1108.

## Slide 71

## Slide 73

## Will routine fetal karyotyping become obsolete? 

- Analysis of fetal DNA in maternal blood
- not quite ready for prime time
- may make invasive testing obsolete
- single nucleotide polymorphisms (SNP)
- DNA microarrays
- array-based comparative genomic hybridization (array CGH)
- rapid detection (no cell culture)
- cost  issues at present

## Am J Hum Genetics; 2004; 74;1168

## Slide 76

## PRENATAL CARRIER SCREENING FOR CYSTIC FIBROSIS

## CASE #4

- A 30 y/o G1P0 Caucasian couple present at 8 weeks desiring testing for cystic fibrosis (CF). The husband’s brother has recently died of pulmonary complications of CF. How should you proceed?

## CYSTIC FIBROSISMOLECULAR BIOLOGY

- CF is the most common genetic disorder in Caucasians w/ a carrier frequency of 1/29
- Cause: gene mutation on chrom 7
- Abnormal gene product: CFTR
- Most common mutation in Caucasians (70%) is delta F508
- >900 mutations have been described

## Slide 80

## CYSTIC FIBROSIS IS AUTOSOMAL RECESSIVE

- If both parents carry the mutation a CF mutation:
- -25% of their children will be affected
- -25% of their children will be normal
- -50% of their children will be carriers

## Slide 82

## CYSTIC FIBROSISCOUNSELING ISSUES

- What is her risk of being a carrier?
- What is his risk of being a carrier?
- What is their risk of having a child affected w/ CF?
- (What is the carrier risk for other family members?)

## CF CARRIER RISK BY ETHNIC BACKGROUND

- _ETHNIC_     _INCID_   _CARRIER_  _DETECT_
-  Caucasian    1/3,300      1/29          80%
-  Hispanic       1/8,500      1/46          57%
-  Afr-Am         1/15,300     1/62          69%
-  Asian            1/32,100    1/90          ?
-  NativeAm            ?          ?              ?

## WHO SHOULD BE SCREENED FOR CF? (ACOG)

- FH (+) for CF
- Partners of individuals w/ CF
- Couples in which 1 or both partners are Caucasian who are planning pregnancy or seeking prenatal care
- (low risk groups should be offered information about CF screening)

## CF SCREENING STRATEGIES

- Concurrent vs. sequential screening
- Negative-negative            1:80,000 risk
- Positive-negative              1:560
- Positive-unknown             1:280
- Positive-positive               1:4

## CF SCREENINGEVIDENCE (2000)

- 9 studies                     n=34,193
- (+) results                    n=38
- affected fetuses           n=12
- dx tests per case              3

## CF SCREENING PROCEDURE

- leucocytes or buccal epithelial cells can both provide satisfactory DNA
- pan-ethnic panel of 25 mutations
- results available in ~7 days
- if one partner tests (+), it is recommended that the other partner be tested if available and willing

## CASE (con’t)

- the pt tested negative for all mutations
- her partner tested positive for both the delta F508 and the R117H mutations
- their risk of having an affected child is 1:560 (as a result of an undetected but shared mutation)
- they felt comfortable declining CVS

## CONCLUSIONSACOG RECOMMENDATIONS 

- offering screening for NTD and DS is standard of care for all pregnancies
- 1st trimester screening for DS is an effective option
- prenatal screening for CF should be offered to couples if 1 or both are Caucasian
- prenatal screening should always be a matter of personal choice