[EMB] 18: Prenatal Diagnosis

830 women

Every day, about____________ die due to preventable causes related to pregnancy and childbirth around the worl

to determine whether a fetus believed to be at risk for some genetic disease is or is not actually affected.

The objective of prenatal diagnosis is

BIRTH DEFECTS

These are Congenital malformation or anomaly

Environmental, Genetic, Multifactorial

What are the main causes of birth defectss?

3rd to 8th week

Most sensitive period for inducing birth defects is the_____________ AOG (embryogenesis)

Rubella

What virus teratogen in the first 14 weeks causes Cataract, cardiac problems, deafness

Cytomegalovirus (CMV)

What virus teratogen in the first 14 weeks causes Hearing loss?

Herpes simplex

What virus teratogen in the first 14 weeks causes Autism?

Varicella

What virus teratogen in the first 14 weeks causes Microcephaly, hypoplasia?

Coxsackie

What virus teratogen in the first 14 weeks causes Spontaneous abortion?

Mumps and measles

What virus teratogen in the first 14 weeks causes Late fetal death?

Hepatitis B

What virus teratogen in the first 14 weeks causes Neonatal hepatitis?

Toxoplasmosis

What virus teratogen in the first 14 weeks causes Hydrocephalus?

Thalidomide

What drug teratogen in the first 14 weeks causes Phocomelia (limb defects)?

Isotretonoin

What drug teratogen in the first 14 weeks causes Cleft lip, mental retardation?

Anti-convulsants Illicit drugs Tranquilizers Alcohol

What are the other drug teratogen?

Uncontrolled DM

What maternal disease can cause stillbirth, LGA (large for gestational age babies)

Phenylketonuria

What maternal disease can cause microcephaly, cardiac defect?

The number of oocytes is predetermined at birth, No new oocytes are formed throughout life, Progressive maturation of follicles in aging

Why is advanced maternal age a possible teratogen?

False

(T/F) Consanguinity (2nd–3rd degree)decreases congenital

defect risk

genetic testing and prenatal

In these cases, for whatever reason the mother gets pregnant for the first time at 35 years old, _______________________ diagnosis will be highly recommended.

Ultrasound

This uses high-frequency sound waves for imaging and can be performed via transabdominal (TAS), transrectal (TRS), or transvaginal (TVUS) approaches.

5th to 10th week AOG:

At what week is ultrasound used as a parameter used to check the status of the fetus is the crown rump length

biparietal diameter (BPD), femur length (FL), and abdominal circumference (AC).

Beyond the 10th week of age of gestation, ultrasound parameters used include

Nuchal translucency

________________ is best assessed at 11–14 weeks of age of gestation and refers to fluid accumulation seen at the posterior aspect of the fetal neck.

○ Gestational age

○ Identify twins

○ Fetal position

○ Placental location
○ Fetal growth, development, and movement

○ Structural birth defects

○ Amniotic fluid volume

What can be identified in ultrasound?

16th-20th week AOG

Fetal organ systems and anatomical lesions: best looked at during what AOG?

blighted ovum or missed abortion, and Down syndrome.

What conditions can be dtected by ultraosund?

Down syndrome.

Abnormal nuchal translucency may indicate the need to evaluate for what?

detect cleft lip or palate

Ultrasound can also provide 3D imaging of the fetal face to _________________,

fetal heartbeat.

Doppler ultrasound can be used to detect the _____________

early first trimester

When is the accuracy of fetal aging using ultrasound best at ?

Maternal serum alpha-fetoprotein (MSAFP)

This is a protein produced initially by the yolk sac and later by the fetal liver, which enters the amniotic fluid through fetal urine and reaches maternal circulation via the placenta.

14 weeks of age of gestation

Maternal serum alpha-fetoprotein (MSAFP) peaks around what week?

30 weeks

Maternal serum alpha-fetoprotein (MSAFP) decreases around what week?

neural tube defects, omphalocele, gastroschisis, bladder exstrophy, amniotic band syndrome, sacrococcygeal teratoma, and intestinal atresia.

What can be indictaed by increased MSAFP?

Down syndrome, trisomy 18, sex chromosome abnormalities, and triploidy.

What can be indictaed by decreased MSAFP?

15–20 weeks

Alpha-fetoprotein (AFP) screening at _____________ of gestation is used to detect neural tube defects (NTDs) and may be supported by ultrasound findings suggestive of these abnormalities.

False. higher

(T/F) The risk of NTDs is lower if there is a previous child with NTD or a family history of NTDs, especially if the mother is affected.

uncontrolled maternal type 1 diabetes, exposure to drugs such as valproic acid, and elevated maternal serum AFP (MSAFP) levels.

What are the additional risk factors in screening for NTD?

• screening test and may miss some neural tube defects, and

• cause minor complications such as pain or bruising at the incision site, which usually resolve within a few days.

What are teh limitations of AFP?

Human chorionic gonadotropin (hCG)

This is a dimeric hormone composed of a 145-amino-acid beta subunit and a 92-amino-acid alpha subunit, with the beta subunit being unique to hCG.

within days after fertilization,

When does Beta-HCG become detectable?

False: 2 days at 4 weeks, 3.5 at 6

(T/F) Beta HCG blood levels typically double every 3.5 days during the first 4 weeks of pregnancy and every 2 days at around 6 weeks.

Lower serum beta-hCG

__________________ levels are associated with a decreased likelihood of an ongoing normal pregnancy.

Elevated beta-hCG

________________levels are expected in multiple pregnancies, molar pregnancy, and Down syndrome.

False. increase

(T/F) Decreased beta-hCG in non-viable pregnancies may also be seen in conditions such as miscarriage, ectopic pregnancy, pituitary overproduction of hCG, trophoblastic disease, and phantom hCG.

Screening for fetal Down syndrome

This shows an increased risk when there is advanced maternal age, low maternal serum alpha-fetoprotein (MSAFP), low estriol, and high hCG levels.

Estriol

_________ serves as a marker of fetal health and well-being,

low unconjugated estriol (uE3 or free estriol)

Abnormally ________________________ may indicate chromosomal or congenital abnormalities.

Ultrasound

This may be used to guide invasive procedures such as amniocentesis, chorionic villus sampling (CVS), cordocentesis, and various fetal biopsies.

Amniocentesis

This is a diagnostic procedure in which fetal cells shed into the amniotic fluid during development are collected for analysis.

15–20 weeks

In amniocentesis, after these weeks of pregnancy, a small volume of amniotic fluid is obtained by inserting a needle through the abdominal wall.

20–30 mL

In amniocentesis, about this amount of fluid is collected and analyzed for alpha-fetoprotein (AFP) and cholinesterase levels.

amniotic fluid

The fetal cells present in what fluid can undergo karyotyping or genetic analysis, including evaluation of chromosome banding patterns, wehre Further analyses may include PCR and genotyping assays for specific genetic conditions.

enzyme activity, hormones, amino acids, and detect abnormal metabolites.

Amniotic fluid can be used to measure:

True

(T/F) Amniocentesis has a greater than 99% accuracy for diagnosing Down syndrome but cannot detect all birth defects

second trimester.

Amniocentesis carries a slight risk of miscarriage when performed in this trimester

Amniotic sac infection, Preterm labor, Respiratory distress, Failure of puncture wound to heal

What are the maternal complications of Amniocentesis?

Fetal deformities, Rhesus immunization, Trauma, Perinatal mortality

What are the fetal complications of Amniocentesis?

Transabdominal & Transcervical

What are the 2 approaches of Chorionic Villus Sampling (CVS)

5–30 mg of villus tissue

Chorionic villus sampling (CVS) involves aspirating about ____________________ from the placenta for genetic analysis.

2–3 days

Chorionic villus sampling (CVS) analysis typically takes how long? and allows direct examination of fetal cells without the need for culture.

usually at 10–12 weeks

At what earliest time can Chorionic villus sampling (CVS be performed>?

Antepartum hemorrhage

What are the maternal complications of chorionic villus sampling (CVS)?

Spontaneous abortion and increased risk of limb reduction defects

What are the fetal complications of chorionic villus sampling (CVS)?

Cordocentesis, also known as percutaneous umbilical cord blood sampling,

This is a diagnostic genetic test that examines fetal blood from the umbilical cord to detect abnormalities.

At 18–23 weeks of age of gestation.

When is cordocentesis best performed?

Chromosomal abnormalities (e.g., Down syndrome), fetal blood disorders (e.g., anemia, hemolytic disease), Rh incompatibility, and infections.

What conditions can cordocentesis detect?

From the umbilical vein in the umbilical cord embedded in Wharton’s jelly (which contains 2 arteries and 1 vein).

From where is the sample obtained in cordocentesis?

Fetal bradycardia, fetal or uterine infection (chorioamnionitis), premature rupture of membranes leading to early delivery, placental separation, puncture site bleeding, cord hematoma, and fetal loss.

What are the complications of cordocentesis?

It helps identify possible complications during birth, guides management of the remaining pregnancy, prepares parents for a child with abnormalities, and may improve outcomes through fetal treatment.

What are the benefits of prenatal diagnosis?

to treat the fetus and correct defects before birth.

What is the ultimate goal of prenatal diagnosis in the future?

fetal transfusion

A procedure used to treat fetal anemia, commonly due to red cell immunization or Parvovirus B19 infection during pregnancy.

To keep the fetus healthy until it is mature enough for delivery.

What is the purpose of fetal transfusion?

Ultrasound is used to determine the position of the fetus in the uterus.

How is fetal transfusion guided?

A needle is inserted through the mother’s abdomen into the uterus.

How is fetal transfusion procedure performed?

Compatible donor red blood cells are transfused into the fetus.

What is transfused during fetal transfusion?

It can be given to the mother, allowing the medication to cross the placenta and reach the fetus.

How can fetal medical treatment be administered indirectly?

It can be given directly to the fetus through intramuscular injection (gluteus) or via the umbilical vein.

How can fetal medical treatment be administered directly?

Fetal surgery

This involves highly complex procedures performed in the womb to repair birth defects and improve long-term outcomes in children.

Open fetal surgery -

This involves complete opening of the uterus to operate on the fetus

Maternal hysterotomy

This is a procedure in which the uterus is opened, the surgeon resects the tumor, the fetus is returned to the uterus, and the uterus is then closed.

Spina bifida repair

This involves opening the uterus, exposing the affected area of the spine, repairing the defect, and then closing the uterus.

Meningomyelocele

This is the most severe form of spina bifida, in which the fetal spinal cord fails to close during development.

The baby’s sternum is opened, the pericardial teratoma is exposed, and then surgically removed.

How is pericardial teratoma removed in fetal surgery?