methods of investigation and screening of the pregnant woman

8/8/2019 Methods of Investigation and Screening of the Pregnant Woman

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Presented by: Abhinay BhugooML-510

September 2010


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` First trimester screening is a combination of fetal ultrasound and maternal bloodtesting performed during the first trimester of pregnancy. This screening processcan help to determine the risk of the fetus having certain birth defects.Screening tests may be used alone or in combination with other tests.(11th -14th week)

` ultrasound test for fetal nuchal translucency (NT)Nuchal translucency screening uses an ultrasound test to examine the area at

the back of the fetal neck for increased fluid.` Nasal bone visibility

not visible in downs syndrome

` two maternal serum (blood) testsThe blood tests measure two substances found in the blood of all pregnantwomen: pregnancy-associated plasma protein screening (PAPP-A) - a protein produced by the

placenta in early pregnancy. Abnormal levels are associated with an increased risk forchromosome abnormality.

Beta-human chorionic gonadotropin (-hCG) - a hormone produced by the placenta inearly pregnancy. Abnormal levels are associated with an increased risk for chromosomeabnormality.


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` Used for diagnosis of birth defects such as Down

syndrome, trisomy 18, or trisomy 13.


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` Usually between the 15th and 20th weeks of

pregnancy

` alpha-fetoprotein screening (AFP) - a blood test that

measures the level of alpha-fetoprotein in the mothers'

blood during pregnancy. AFP is a protein normally

produced by the fetal liver and is present in the fluid

surrounding the fetus (amniotic fluid), and crosses the

placenta into the mother's blood. The AFP blood test is

also called MSAFP (maternal serum AFP).


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`Abnormal levels of AFP may signal the

following: open neural tube defects (ONTD) such as spina bifida

Down syndrome other chromosomal abnormalities

defects in the abdominal wall of the fetus

twins - more than one fetus is making the protein

a miscalculated due date, as the levels vary throughout

pregnancy


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Diagram of alpha-fetoprotein (AFP) concentration across gestational age infetal plasma, amnionic fluid, and maternal

serum. The scale refers to the fetal plasma level, which is approximately150 times greater than the amnionic fluid

concentration and 50,000 times greater than the maternal serumconcentration.


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` hCG - human chorionic gonadotropin hormone (a

hormone produced by the placenta)

` estriol - a hormone produced by the placenta

` inhibin - a hormone produced by the placenta


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` Abnormal test results of AFP and other markers may

indicate the need for additional testing.

` ultrasound is performed to confirm the dates of the

pregnancy and to look at the fetal spine and other body

parts for defects.

` amniocentesis


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` An amniocentesis is a procedure used to obtain a small

sample of the amniotic fluid that surrounds the fetus to

diagnose chromosomal disorders and open neural tube

defects (ONTDs) such as spina bifida

` between the 15th and 20th weeks of pregnancy who areat increased risk for chromosome abnormalities, such as

women who are over age 35 years of age at delivery, or

those who have had an abnormal maternal serum

screening test` small risk of miscarriage associated with amniocentesis


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` Chorionic villus sampling (CVS) is a prenataltest that involves taking a sample of some of theplacental tissue

` This tissue contains the same genetic materialas the fetus and can be tested for chromosomalabnormalities and some other genetic problems.

` Ultrasound is used to guide the catheter (fortransvaginal CVS) or needle (for transabdominal

CVS) into place near the placenta.


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` Using a fetoscope (a type of stethoscope) to listen to

the fetal heart beat is the most basic type of fetal heart

rate monitoring.

` Another type of monitoring is with a hand held Doppler

device

` During contractions, an external tocodynamometer (a

monitoring device that is placed over the top of the

uterus with a belt) can record the patterns of

contractions.` Cardiotocography(CTG)


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` glucose tolerance test

A glucose tolerance test, usually conducted in the

24 to 28 weeks of pregnancy, measures levels of

sugar (glucose) in the mother's blood. Abnormalglucose levels may indicate gestational diabetes.

` Rhesus factor

Hemolytic disease of newborn


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` found in the lower genital tract of about 25 percent

of all women.

` GBS may cause chorioamnionitis (a severe

infection of the placental tissues) and postpartuminfection

` GBS is the most common cause of life-threatening

infections in newborns, including pneumonia and

meningitis.


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` cystic fibrosis

` Duchenne muscular dystrophy

` hemophilia A

` thalassemia` sickle cell anemia

` polycystic kidney disease

` Tay-Sachs disease


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Genetic screening methods may include the following:

` ultrasound scan

` alpha-fetoprotein test (AFP) or multiple marker test

` chorionic villus sampling (CVS)` amniocentesis

` percutaneous umbilical blood sampling (withdrawing asmall sample of the fetal blood from the umbilical cord)


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weeks

First visit 15-20 24-28 29-41

history

complete

updated

Physical examination

complete

Blood pressure

maternal weight

Pelvic cervical

examination

Fundal height

Fetal heart

rate/position

A Performed at 28 weeks, if indicated.BTest should be offered.C High-risk women should be retested at the beginning of the third

trimester.DHigh-risk women should be screened at the first prenatal visitand again in the third trimester.E Rectovaginal culture should be obtained between 35 and 37weeks.


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weeks

First visit 15-20 24-28 29-41

Laboratory test

Hemotocrite of

hemoglobin

Blood type and Rh factor

Antibody screening A

Pap smear screening

Glucose tolerance test

Fetal aneuploidy

screening

Ba and/or B

Neural-tube defect

screening

B

Cystic fibrosis screening B or B

Urine protein assesment

Urine culture

Rubella serology

Syphilis serology C

Gonococcal culture D D

Chlamydia culture C

Hepatitis B serology

HIV serology B

Group B streptococcus

culture

E


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` 1. Diagnosis and confirmation of early pregnancy

The gestational sac can be visualized as early as

four and a half weeks of gestation and the yolk

sac at about five weeks. The embryo can beobserved and measured by about five and a half

weeks. Ultrasound can also very importantly

confirm the site of the pregnancy is within the

cavity of the uterus.


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` 2. Vaginal bleeding in early pregnancy.

The viability of the fetus can be documented in

the presence ofvaginal bleeding in early

pregnancy.` visible heartbeat

` Missed abortions and blighted ovum will usually

give typical pictures of a deformed gestational sac

and absence of fetal poles or heart beat.


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` 3. Determination of gestational age and

assessment of fetal size (foetometry)

a) The Crown-rump length (CRL)

b) The Biparietal diameter(BPD)c) The Femur length (FL)

d) The Abdominal circumference (AC)


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` 4. Diagnosis of fetal malformation (can usually

be made before 20 weeks).

` Common examples include hydrocephalus,

anencephaly, myelomeningocoele,achondroplasia and other dwarfism, spina bifida,

exomphalos, Gastroschisis, duodenal atresia

and fetal hydrops.

` . With more recent equipment, conditions suchas cleft lips/ palate and congenital cardiac

abnormalities are more readily diagnosed and at

an earlier gestational age.


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` 5. Placental localization.` 6. Multiple pregnancies.` 7. Hydramnios and Oligohydramnios` 8. Other areas.Ultrasonography is of great value in other obstetric conditions

such as:a) confirmation of intrauterine death.

b) confirmation of fetal presentation in uncertain cases.c) evaluating fetal movements, tone and breathing in thebiophysical profile.d) diagnosis of uterine and pelvic abnormalities during pregnancy

e.g. fibromyomata and ovarian cyst.


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` Transvaginal Scans

` Doppler Ultrasound

` 3-D and 4-D Ultrasound


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methods of investigation and screening of the pregnant woman

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