OBGYN 2 FETAL SCREENING & SYNDROMES

A comprehensive set of 130 practice flashcards covering prenatal screening, chromosomal abnormalities, and congenital syndromes based on lecture notes.

What is a syndrome?

The occurrence of more than one concurrent medical condition or anomaly in a patient.

What is Nuchal Translucency (NT)?

A fluid-filled space at the back of the fetal neck measured by ultrasound in the first trimester combined test.

What does PAPP-A stand for?

Pregnancy-Associated Plasma Protein-A.

What is hCG?

Human Chorionic Gonadotropin, a hormone produced by the placenta.

Describe Chorionic Villus Sampling (CVS).

A diagnostic procedure removing placental tissue using a transcervical catheter or transabdominal needle.

What is the gold standard of prenatal screening with zero miscarriage risk?

NIPT (Non-Invasive Prenatal Testing).

How is amniocentesis performed?

By withdrawing amniotic fluid via a needle through the maternal abdomen into the uterus.

What is the primary current use for cordocentesis?

Fetal blood transfusions.

Which four markers are measured in a Quad Screen?

AFP, hCG, Estriol ($uE3$), and Inhibin-A.

Where is Alpha-Fetoprotein (AFP) produced?

By the fetal yolk sac and immature liver cells.

What is Estriol ($uE3$)?

An estrogen-based hormone produced by the placenta.

What is Inhibin-A?

A hormone produced by placental cells.

What is a karyotype?

A test evaluating the size, shape, and number of chromosomes in body cells.

How is a genome defined?

A person's entire set of DNA containing all genes.

What is a chromosome?

A thread-like structure inside the cell nucleus.

What does the term haploid refer to?

One set of $23$ chromosomes.

What does the term diploid refer to?

Two sets of $46$ chromosomes, which is the normal count.

What is triploid?

Three sets of chromosomes ($69$ total), which is a lethal condition.

Define Trisomy.

Having three chromosomes at one position instead of a matched pair.

What is Monosomy?

Having only one chromosome at a position, such as Turner Syndrome ($45,X$).

What is Full Trisomy?

An extra chromosome present in every cell of the body.

What is Partial Trisomy?

Only part of an extra chromosome is present.

What is Mosaic Trisomy?

An extra chromosome present in only some cells of the body.

What is another name for Trisomy $21$?

Down Syndrome.

What is the incidence of Down Syndrome?

Approximately $1 ext{ in } 800$ births.

What is another name for Trisomy $18$?

Edwards Syndrome.

What is another name for Trisomy $13$?

Patau Syndrome.

What is hypotonia?

Reduced muscle tone resulting in "floppiness."

What is the "Sandal Gap"?

A large space between the first and second toe; a key exam point for Trisomy $21$.

What is clinodactyly?

A little finger that curves inwards.

What is a single palmar crease?

A palm with only one crease across it.

What is an epicanthic fold?

A skin fold running vertically between eyelids at the inner corner of the eye.

What is an AV Canal Defect?

An atrioventricular septal defect affecting atria and ventricles, often called a "butterfly heart."

What does the "Double Bubble Sign" indicate on ultrasound?

Duodenal atresia, associated with Trisomy $21$.

Define pyelactasis.

Mild dilation of the fetal renal pelvis in utero.

What is echogenic bowel?

A bright appearance of fetal bowel on ultrasound; a soft marker for Trisomy $21$.

What is a rocker bottom foot?

A foot deformity with a vertical talus; a key feature of Trisomy $18$.

Which trisomy is associated with a strawberry-shaped skull?

Trisomy $18$.

What is dolichocephaly?

An elongated skull shape.

Define micrognathia.

A small jaw.

What is microcephaly?

A small head.

What is microphthalmia?

Small eyes.

What is holoprosencephaly?

Failure of the forebrain to divide into two hemispheres; common in Trisomy $13$.

What is hypotelorism?

Eyes positioned abnormally close together.

What is a proboscis?

A nose-like structure protruding from the forehead; a finding in Trisomy $13$.

What is cyclopia?

The presence of a single eye.

What is polydactyly?

The presence of extra fingers or toes.

What is an encephalocele?

A neural tube defect where brain tissue protrudes through a skull opening.

What is a meningomyelocele?

A neural tube defect involving the spinal cord and meninges.

What is an omphalocele?

A covered abdominal wall defect where organs protrude through the abdominal wall.

What is gastroschisis?

An uncovered abdominal wall defect associated with elevated AFP.

What is macroglossia?

An enlarged tongue; a cardinal feature of Beckwith-Wiedemann Syndrome.

What is macrosomia?

Large body size or large birth weight.

What is visceromegaly?

Enlargement of abdominal organs like the kidneys, liver, and pancreas.

What is hemihypertrophy?

Lateralized overgrowth where one side of the body is larger than the other.

Which pediatric renal tumor is associated with Beckwith-Wiedemann Syndrome?

Wilms Tumor.

What causes severe hypoglycemia in Beckwith-Wiedemann Syndrome?

Hyperinsulinism.

What is the classic triad of Meckel-Gruber Syndrome?

Encephalocele, infantile polycystic kidneys, and polydactyly.

What is another name for Prune Belly Syndrome?

Eagle-Barrett Syndrome.

What is the clinical triad for Prune Belly Syndrome?

Abdominal muscle deficiency, cryptorchidism, and urinary tract abnormalities.

What is cryptorchidism?

Failure of the testes to descend in male infants.

What does the acronym TORCH stand for?

Toxoplasmosis, Other (syphilis/varicella/mumps/HIV), Rubella, Cytomegalovirus ($CMV$), and Herpes.

How is Toxoplasmosis typically spread?

By undercooked food, infected cat feces, or mother-to-child transmission.

What is the chromosomal makeup of Turner Syndrome?

$45,X$ (only one X chromosome).

What is the chromosomal makeup of Klinefelter Syndrome?

$47,XXY$ (an extra X chromosome in males).

What is a classic physical feature of Turner Syndrome?

Webbed neck.

What is lymphedema in the context of Turner Syndrome?

Puffiness or swelling of the hands and feet.

What heart condition is specifically associated with Turner Syndrome?

Coarctation of the Aorta.

What is gynecomastia?

Enlarged breast tissue in males; a finding in Klinefelter Syndrome.

What are the features of Limb-Body Wall Complex (LBWC)?

Anterior body wall openings, body attached to placenta, and short/missing umbilical cord.

What causes amputations or facial clefts in Amniotic Band Syndrome?

Fetal entanglement in fibrous amniotic bands that restrict blood flow.

When is Rh sensitization a clinical risk?

When the mother is Rh-negative and the fetus is Rh-positive.

What does IUGR stand for?

Intrauterine Growth Restriction.

What is polyhydramnios?

Excessive amniotic fluid.

What characterizes a cystic placenta?

An immature placenta filled with cysts; characteristic of Triploidy.

What is a targeted ultrasound?

A comprehensive second-trimester evaluation of fetal anatomy.

What does AFI stand for?

Amniotic Fluid Index.

True or False: Screening tests are only offered to high-risk patients.

FALSE. They are offered to both high-risk and low-risk populations.

What two lab values are measured in the First Trimester Combined Test?

PAPP-A and hCG.

What is the normal measurement for Nuchal Translucency?

Less than $3 ext{ mm}$.

In what timeframe is first trimester screening typically performed?

Between weeks $11$ and $14$ of pregnancy.

How many exams must a sonographer perform for NT accreditation?

$40$–$50$ exams.

What factors determine risk in the first trimester screen?

Patient age, lab values (PAPP-A and hCG), and the NT measurement.

When is CVS typically performed?

Between weeks $10$ and $14$ of pregnancy.

What is the approximate miscarriage risk for CVS?

Approximately 0.7 ext{%}.

Does CVS detect neural tube defects?

NO.

Why is CVS not recommended before week $10$?

Due to the risk of limb defects.

What trisomies are screened via NIPT?

Trisomy $21$, Trisomy $18$, and Trisomy $13$.

When is the Quad Screen performed?

Between weeks $15$ and $20$ of pregnancy.

Which Quad Screen marker is NOT produced by the placenta?

AFP (Alpha-Fetoprotein).

What is the Quad Screen pattern for Trisomy $21$?

AFP $ext{low}$, hCG $ext{high}$, Estriol $ext{low}$, Inhibin-A $ext{high}$.

What is the Quad Screen pattern for Trisomy $18$?

All four markers (AFP, hCG, Estriol, Inhibin-A) are low.

What is an elevated AFP indicative of?

Neural tube defects, abdominal wall defects, or multiple gestations.

When is amniocentesis typically performed?

Between weeks $15$ and $18$ of pregnancy.

What is the approximate miscarriage risk for amniocentesis?

Approximately 0.6 ext{%}.

When is amniocentesis preferred over CVS?

When there is a history or risk of neural tube defects.

In what order do CVS, amniocentesis, and AFI occur?

CVS ($10$–$14 ext{ weeks}$), then amniocentesis ($15$–$18 ext{ weeks}$), then AFI (second trimester).

When is cordocentesis usually performed?

After approximately $18 ext{ weeks}$ (around $20 ext{ weeks}$).

How many pairs of chromosomes do humans have?

$23 ext{ pairs}$ ($46 ext{ total}$).

How is a male identified on a karyotype?

By the presence of one X and one notably small Y chromosome ($XY$).