Prenatal Testing Flashcards
Why is CVS preferred over amniocentesis for early genetic diagnosis?
a. CVS has a lower risk of fetal loss.
b. CVS is performed earlier in pregnancy, allowing earlier decision-making.
c. CVS can detect open neural tube defects.
d. CVS results are always faster than amniocentesis results.
Answer: b. CVS is performed earlier in pregnancy, allowing earlier decision-making. (Correct)
CVS is performed at 11–13 weeks, enabling earlier diagnosis and planning.
a. CVS has a lower risk of fetal loss. (Incorrect)
Fetal loss risk is comparable for both procedures.
c. CVS can detect open neural tube defects. (Incorrect)
Why can’t CVS screen for open neural tube defects (NTDs)?
Reasoning:
CVS analyzes placental tissue for genetic or chromosomal abnormalities but does not assess the amniotic fluid or fetal development directly.
Neural tube defects (e.g., spina bifida, anencephaly): These are structural abnormalities in the developing brain or spinal cord. Detecting NTDs requires:
Measuring maternal serum alpha-fetoprotein (MSAFP): A protein produced by the fetus that leaks into the maternal bloodstream when there’s an open defect.
Conducting ultrasound imaging: This can identify structural abnormalities in the fetus.
Why CVS is not sufficient:
CVS does not involve sampling amniotic fluid, which contains alpha-fetoproteins that indicate NTDs.
Additional tests, like MSAFP or a detailed ultrasound, are required to diagnose open neural tube defects.
CVS does not screen for neural tube defects; additional testing is required.
d. CVS results are always faster than amniocentesis results. (Incorrect)
Both tests can use rapid FISH analysis, providing results in 24–48 hours.
Why is the timing of the procedure different for CVS and amniocentesis?
Timing:
CVS (Chorionic Villus Sampling): Performed earlier, between 11 and 13 weeks of pregnancy.
Amniocentesis: Performed later, between 15 and 22 weeks (or beyond for specific indications).
Explanation:
CVS: This test collects cells from the chorionic villi, which are tiny finger-like projections of the placenta. The placenta forms early in pregnancy, so CVS can be conducted earlier than amniocentesis.
Amniocentesis: This test samples amniotic fluid, which surrounds the baby in the uterus. A sufficient amount of fluid and mature fetal cells are needed for accurate testing, which typically occurs after 15 weeks.
What does “Chorionic Villus” mean?
Chorionic: Relating to the chorion, which is the outermost membrane surrounding the embryo and part of the placenta.
Villus: A small, finger-like projection that increases surface area. Chorionic villi facilitate nutrient and gas exchange between the mother and the fetus.
What is a major advantage of non-invasive prenatal testing (NIPT) over invasive procedures like CVS and amniocentesis?
a. NIPT can detect open neural tube defects.
b. NIPT provides faster results for chromosomal abnormalities.
c. NIPT carries no risk of miscarriage.
d. NIPT detects all genetic conditions.
Answer: c. NIPT carries no risk of miscarriage. (Correct)
NIPT is a blood test and does not involve invasive sampling, avoiding miscarriage risk.
a. NIPT can detect open neural tube defects. (Incorrect)
NIPT does not screen for neural tube defects; follow-up testing is required.
b. NIPT provides faster results for chromosomal abnormalities. (Incorrect)
Both FISH testing and NIPT provide rapid results for specific aneuploidies.
d. NIPT detects all genetic conditions. (Incorrect)
NIPT focuses on common aneuploidies and some microdeletions, not all genetic conditions.
more information:
NIPT (Non-Invasive Prenatal Testing):
Involves analyzing cell-free fetal DNA (cffDNA) found in the maternal blood.
It is non-invasive because it only requires a maternal blood sample and does not physically interfere with the fetus or pregnancy structures.
Why does miscarriage occur in invasive tests?
CVS and amniocentesis involve invasive procedures:
Needle or catheter insertion: These pierce the uterus or placenta, which may lead to complications such as:
Infection.
Bleeding.
Premature rupture of membranes (amniotic sac).
Unintentional harm to the fetus.
These complications can cause pregnancy loss, though the risk is small with experienced operators (e.g., 0.15–0.3% for amniocentesis).
Why NIPT is safer:
It eliminates the need for invasive techniques, significantly reducing the risk of complications like infection or miscarriage.
Why is RhoGAM administration recommended for Rhesus-negative patients undergoing CVS or amniocentesis?
a. To reduce pain during the procedure.
b. To prevent isoimmunization due to fetal blood cell exposure.
c. To improve diagnostic accuracy.
d. To accelerate recovery post-procedure.
Answer:b. To prevent isoimmunization due to fetal blood cell exposure. (Correct)
Isoimmunization occurs if maternal antibodies target fetal red blood cells, potentially harming future pregnancies.
Isoimmunization, also known as alloimmunization, occurs when a person’s immune system produces antibodies against antigens on red blood cells that are foreign to their own. This can happen during pregnancy when the blood of the mother and fetus mix, and the fetus has a different blood type, particularly involving the Rhesus (Rh) factor.
a. To reduce pain during the procedure. (Incorrect)
RhoGAM does not alleviate pain; it is an immunoprophylactic agent.
c. To improve diagnostic accuracy. (Incorrect)
RhoGAM does not affect diagnostic accuracy.
d. To accelerate recovery post-procedure. (Incorrect)
RhoGAM has no effect on recovery time.
How does isoimmunization happen:
How Isoimmunization Happens
Rhesus (Rh) Incompatibility
If the mother is Rh-negative (lacks the RhD antigen) and the fetus is Rh-positive (inherited from the father), fetal red blood cells can enter the mother’s bloodstream.
The mother’s immune system recognizes the RhD antigen as foreign and produces anti-D antibodies to target it.
Subsequent Pregnancies
In later pregnancies with an Rh-positive fetus, these pre-formed antibodies can cross the placenta and attack the fetal red blood cells, leading to hemolytic disease of the fetus and newborn (HDFN).
This results in anemia, jaundice, or even more severe complications like hydrops fetalis (a life-threatening condition).
Key Causes of Blood Mixing
Invasive Procedures: Chorionic villus sampling (CVS) or amniocentesis can cause fetal blood cells to enter the mother’s circulation.
Trauma: Abdominal injury during pregnancy.
Delivery: Fetal-maternal hemorrhage is common during childbirth.
Miscarriage or Abortion: Can also lead to blood mixing.
Prevention and Management
RhoGAM (RhD-immune globulin):
Administered to Rh-negative mothers during pregnancy and after delivery (or after invasive procedures).
Prevents isoimmunization by neutralizing any fetal Rh-positive red blood cells before the mother’s immune system reacts to them.
What is a key limitation of CVS compared to amniocentesis?
a. CVS has a higher risk of fetal loss.
b. CVS cannot screen for open neural tube defects.
c. CVS requires general anesthesia.
d. CVS is not guided by ultrasound.
Answer: b. CVS cannot screen for open neural tube defects. (Correct)
Neural tube defects require follow-up with maternal serum alpha-fetoprotein (MSAFP) or ultrasound.
a. CVS has a higher risk of fetal loss. (Incorrect)
Fetal loss risks for CVS and amniocentesis are similar.
c. CVS requires general anesthesia. (Incorrect)
CVS is typically performed under local anesthesia or sedation.
d. CVS is not guided by ultrasound. (Incorrect)
Both procedures are guided by ultrasound.
Why is Rho(D) immune globulin administered within 72 hours to Rh-negative pregnant patients after certain events?
A) To reduce the risk of alloimmunization.
B) To detect fetal chromosomal abnormalities.
C) To enhance fetal growth and development.
D) To prevent first-trimester pregnancy loss.
Correct Answer: A
Why A is correct: Rho(D) immune globulin prevents alloimmunization, which occurs when an Rh-negative mother develops antibodies against Rh-positive fetal blood cells. This is crucial after events like trauma or pregnancy loss.
Why B is incorrect: Rho(D) immune globulin does not assess or treat chromosomal abnormalities.
Why C is incorrect: It does not directly influence fetal growth.
Why D is incorrect: While it may help in future pregnancies by preventing alloimmunization, its primary purpose is not to prevent first-trimester loss.
More information
Rho(D) immune globulin is a medication used to prevent alloimmunization in Rh-negative mothers. This occurs when an Rh-negative mother’s immune system detects Rh-positive fetal blood cells (from the fetus) as foreign and produces antibodies against them. These antibodies can attack the fetus in future pregnancies, causing serious complications (like hemolytic disease of the newborn). The administration of Rho(D) immune globulin prevents the mother from developing these antibodies, reducing the risk of complications in future pregnancies, especially following events like trauma, ectopic pregnancy, or early pregnancy loss.
What is the main advantage of integrating first- and second-trimester screenings?
A) Reduced cost compared to separate screenings.
B) Highest detection rate for trisomy 21.
C) Eliminates the need for NT ultrasound.
D) Lower false-positive rate than NIPT.
B is correct: Combining first-trimester screening (NT, PAPP-A) and second-trimester quad screen improves the detection rate for trisomy 21 to 94–96%, the highest among noninvasive options.
A) is incorrect: Integrated screening may increase costs due to multiple tests across trimesters.
C) is incorrect: NT ultrasound remains a key component of integrated screening.
D) is incorrect: NIPT has a lower false-positive rate (<1%) compared to integrated screening (5%).
Which serum analyte pattern is associated with trisomy 21 in the second trimester?
A) High MSAFP, low hCG, low uE3, low inhibin A
B) Low MSAFP, high hCG, low uE3, elevated inhibin A
C) High MSAFP, high hCG, high uE3, elevated inhibin A
D) Low MSAFP, low hCG, low uE3, elevated inhibin A
b) hCG and inhibin A are elevated, making this pattern characteristic of Down syndrome.
A) is incorrect: High MSAFP is not associated with trisomy 21; it can indicate neural tube defects.
C) is incorrect: All analytes being high does not fit the typical pattern for trisomy 21.
D) is incorrect: Low hCG and low inhibin A are not characteristic of trisomy 21; this pattern better fits trisomy 18.
What is the primary limitation of first-trimester screening for chromosomal abnormalities?
A) It is not available for multiple pregnancies.
B) False-positive results can cause anxiety and lead to additional testing.
C) It cannot detect trisomy 18.
D) It cannot provide early results.
Why B is correct: First-trimester screening has a 5% false-positive rate, which can lead to unnecessary stress and invasive testing, such as CVS or amniocentesis.
A) is incorrect: First-trimester screening, especially NT ultrasound, is preferred for multiple pregnancies because serum-only tests are less reliable in these cases.
C) is incorrect: First-trimester screening detects trisomy 18 with a detection rate of >90%.
D) is incorrect: First-trimester screening is performed between 11–13 weeks, offering early results.
CVS stands for Chorionic Villus Sampling. It is a diagnostic test used to obtain a sample of the placenta (chorionic villi) to analyze fetal cells for genetic abnormalities, such as trisomies (e.g., trisomy 13, 18 or 21). In the context of first-trimester screening, if a patient has abnormal screening results (such as a high risk for chromosomal abnormalities), CVS is offered as a confirmatory test to determine if the fetus has a genetic condition.
- Why does this happen in trisomy 21 detection?
In trisomy 21 (Down syndrome), certain serum markers change in a distinct pattern. The pattern includes:
Low MSAFP (Maternal Serum Alpha-Fetoprotein): This is lower than normal because the fetus has a chromosomal abnormality that affects protein production.
Low uE3 (Unconjugated Estriol): Estriol levels are lower in pregnancies with trisomy 21.
High hCG (Human Chorionic Gonadotropin): The hCG levels are elevated in pregnancies with trisomy 21.
Elevated inhibin A (in the quad screen): Inhibin A is higher in trisomy 21, which further helps in detection.
This pattern of altered markers helps healthcare providers identify pregnancies at higher risk for Down syndrome.
Why is serum ferritin considered the best marker of iron status during pregnancy?
A) Ferritin levels increase during pregnancy, indicating iron storage.
B) Ferritin levels remain unaffected by pregnancy.
C) Despite a decline, ferritin provides the most reliable measure of iron status.
D) Other iron markers are more accurate than ferritin in pregnancy.
C) Even though ferritin levels decrease, it is still the most reliable marker for assessing iron status in pregnancy
A) Incorrect: Ferritin levels actually decrease during pregnancy, especially by the third trimester.
B) Incorrect: Ferritin levels decline progressively during pregnancy, so they are not stable.
.
D) Incorrect: Other markers like serum iron and transferrin saturation fluctuate and are less reliable than ferritin.
Why this is true
Ferritin remains the best marker of iron status during pregnancy despite its decline because it directly reflects stored iron in the body. Here’s why:
Reflects Iron Storage: Ferritin levels correspond to the amount of iron stored in the liver, spleen, and bone marrow. This makes it the most direct measure of iron reserves.
Physiological Changes Are Predictable: During pregnancy, ferritin levels naturally decline due to increased blood volume and the demand for iron to support fetal development and placenta formation. This decline is expected and does not invalidate ferritin as a reliable indicator.
Consistency Across Trimesters: While ferritin levels decrease progressively, they still provide a better overall picture of iron status than other markers like transferrin or serum iron, which fluctuate more due to pregnancy-related changes.
Best Indicator of Iron Deficiency: Low ferritin levels are the most sensitive and specific indicator of iron deficiency, even during pregnancy, because they signify depleted iron stores before other markers are affected.
Guides Treatment: Ferritin is essential for diagnosing and managing iron-deficiency anemia, allowing healthcare providers to decide when iron supplementation is necessary.
Why is first-trimester screening preferred for detecting trisomy 21?
A) It has a higher detection rate and earlier results compared to second-trimester screening.
B) It includes maternal age as the only risk factor.
C) It eliminates the need for diagnostic testing.
D) It has a lower false-positive rate than second-trimester screening.
B is correct: Combining first-trimester screening (NT, PAPP-A) and second-trimester quad screen improves the detection rate for trisomy 21 to 94–96%, the highest among noninvasive options.
A) is incorrect: Integrated screening may increase costs due to multiple tests across trimesters.
C) is incorrect: NT ultrasound remains a key component of integrated screening.
D) is incorrect: NIPT has a lower false-positive rate (<1%) compared to integrated screening (5%).
More information:
Combining first-trimester screening (NT and PAPP-A) and second-trimester screening (quad screen) improves the detection rate for trisomy 21 (Down syndrome) to 94–96% for the following reasons:
First-trimester screening (NT ultrasound and serum markers like PAPP-A and β-hCG) assesses early risk factors, including anatomical markers and maternal serum levels.
Second-trimester screening (quad screen) includes additional markers (MSAFP, hCG, uE3, and inhibin A) that are associated with chromosomal abnormalities. By combining both sets of markers from the two screenings, the accuracy in identifying pregnancies at risk for trisomy 21 is higher because it accounts for more variables and provides a more comprehensive picture, improving the chances of detecting the condition.
What is the suggested fasting glucose target for pregnant women to reduce the risk of macrosomia and neonatal hypoglycemia?
A) <4.0 mmol/L
B) <5.0 mmol/L
C) <6.0 mmol/L
D) <7.0 mmol/L
5.0mmol/L×18=90mg/dL
4.0 mmol/Lx18=72mg/dL
6.0mmol/Lx18=108mg/dL
7.0mmol/Lx18=126mg/dL
Correct Answer: B) <5.0 mmol/L
Keeping fasting blood glucose below 5.0 mmol/L is associated with better pregnancy outcomes, including reducing the risk of delivering a baby that is too large (macrosomia) and preventing neonatal hypoglycemia (low blood sugar in the newborn).
Why not A? A fasting glucose target of <4.0 mmol/L is too low and could increase the risk of hypoglycemia in the mother.
Why not C? A target of <6.0 mmol/L is too high to adequately reduce risks.
Why not D? A target of <7.0 mmol/L would not effectively minimize risks for the baby.
Which group is at risk of persistent lipid elevation postpartum?
A) Women with a history of hypothyroidism.
B) Women who experienced GDM or preeclampsia during pregnancy.
C) Women who breastfeed exclusively.
D) Women with hyperlipidemia in late pregnancy.
Correct Answer: B) Women who experienced GDM or preeclampsia during pregnancy.
Women who had gestational diabetes mellitus (GDM) or preeclampsia (a pregnancy-related high blood pressure condition) are more likely to have lingering elevated lipid levels after pregnancy. These conditions can disrupt normal metabolic and lipid regulation, increasing the risk of long-term cardiovascular issues.
Gestational Diabetes Screening
* Screen between 24–28 weeks using clinical or lab tests.
* Low-risk women may skip testing.
A) Hypothyroidism can affect lipids but isn’t directly linked to pregnancy-related lipid changes.
C) Breastfeeding typically helps lower lipid levels faster, not elevate them.
D) Hyperlipidemia during pregnancy usually resolves after delivery in most cases.
Which glycemic control measure is standardized and can be used during pregnancy?
A) Fasting blood glucose
B) Postprandial glucose
C) HbA1c
D) Insulin sensitivity testing
Correct Answer: C) HbA1c
HbA1c is a blood test that reflects average blood sugar levels over the past 2-3 months and is the only glycemic measure that is standardized and reliable during pregnancy. However, it is less accurate if iron deficiency anemia is present, which can be common in pregnancy.
Why not A? Fasting glucose is useful but not standardized for screening purposes during pregnancy.
Why not B? Postprandial glucose (after-meal levels) is important for monitoring but varies by time and testing guidelines.
Why not D? Insulin sensitivity testing isn’t routinely used in pregnancy.
How Can Complications from Invasive Testing Lead to a Miscarriage?
- Infection
Mechanism: Invasive procedures (like CVS or amniocentesis) introduce foreign instruments into sterile environments, such as the uterus. If bacteria enter, they can cause chorioamnionitis (infection of the amniotic sac and surrounding tissues), which may lead to:
Premature rupture of the membranes (amniotic sac).
Inflammation and damage to fetal tissues, making the pregnancy unviable. - Bleeding
Mechanism:
Damage to blood vessels during needle or catheter insertion can cause localized bleeding.
Severe bleeding can disrupt the placenta’s ability to provide oxygen and nutrients, leading to pregnancy loss.
Blood pooling in the uterus can increase pressure, affecting fetal development. - Premature Rupture of Membranes (PROM)
Mechanism: The amniotic sac is a protective barrier for the fetus. If this sac is punctured during an invasive test:
Amniotic fluid may leak, reducing cushioning and increasing the risk of infection.
The fetus becomes vulnerable to compression and underdevelopment of key organs (like the lungs). - Direct Fetal Injury
Mechanism: While rare, the needle or catheter used during CVS or amniocentesis may inadvertently harm the fetus. This can lead to physical trauma or disruption of vital systems, potentially causing the pregnancy to fail.
Why NIPT Does Not Cause Miscarriage
Non-Invasive Nature: NIPT only involves drawing blood from the mother, which has no physical contact with the fetus or pregnancy structures.
No Physical Trauma: The process doesn’t disturb the uterus, placenta, or amniotic sac, thus avoiding the risk of infections, bleeding, or membrane rupture.
By eliminating these risks, NIPT significantly lowers the chance of pregnancy complications compared to invasive testing.
What are the two main approaches for performing chorionic villus sampling (CVS)?
a. Transvaginal and transabdominal
b. Transcervical and transabdominal
c. Transuterine and transabdominal
d. Transcervical and transvaginal
Correct Answer: b. Transcervical and transabdominal
Explanation: CVS can be performed either by inserting a catheter through the cervix (transcervical) or by using a needle through the abdomen (transabdominal) to sample placental tissue. Both methods require ultrasound guidance.
- Techniques:
- Transcervical Approach:
- Uses a sampling catheter passed through the cervix under ultrasound guidance.
- Negative pressure aspirates chorionic villi into a syringe with culture medium.
- Transabdominal Approach:
- Involves a 19- or 20-gauge spinal needle inserted through the abdomen into the placenta.
- Tissue is aspirated and confirmed under a dissecting microscope.
- Guidance: Real-time ultrasound ensures precision.
- Selection: Choice of approach depends on placental location and provider
expertise.
Transvaginal: Often used for early pregnancy ultrasounds or procedures to diagnose ectopic pregnancies, monitor early fetal development, or assess ovarian cysts. It does not involve tissue sampling.
Transcervical: Primarily associated with CVS and hysteroscopy (a diagnostic procedure to view the uterine cavity).
Transabdominal: Used for CVS, amniocentesis, and other procedures such as ultrasound-guided percutaneous umbilical blood sampling (PUBS).
transuterine- Transuterine refers to passing through the uterine wall. This approach is less commonly referenced in diagnostic tests but may apply to specific interventional procedures:
Ultrasound-Guided Fetal Surgery: In cases requiring in-utero surgery, instruments may traverse the uterine wall to address conditions like twin-to-twin transfusion syndrome or spina bifida.
Intrauterine Fetal Transfusions: Used for treating conditions like severe fetal anemia, where blood is directly transfused into the fetus.
Percutaneous Umbilical Blood Sampling (PUBS): This involves sampling fetal blood from the umbilical vein and requires transuterine access.
Which of the following tests can detect open neural tube defects?
a. CVS
b. Amniocentesis
c. NIPT
d. Chorionic villus biopsy
**Correct Answer: b. Amniocentesis
Explanation: Open neural tube defects are detected through maternal serum alpha-fetoprotein (MSAFP) testing or ultrasound, both of which are often part of or follow amniocentesis. CVS cannot detect neural tube defects, and NIPT focuses on chromosomal abnormalities.**
Procedure
* A 20- or 22-gauge spinal needle is guided by ultrasound into the uterine cavity.
* 20–30 mL of amniotic fluid is withdrawn, containing fetal cells for analysis.
a. CVS: Cannot detect open neural tube defects because it does not analyze amniotic fluid or maternal blood markers like alpha-fetoprotein.
c. NIPT: Focuses on detecting aneuploidies (chromosomal abnormalities like trisomies) using cell-free fetal DNA but does not assess neural tube defects.
d. Chorionic villus biopsy: Similar to CVS, it does not test for neural tube defects as it samples placental tissue, not amniotic fluid or maternal blood.
What is a key limitation of expanded panels in non-invasive prenatal testing (NIPT)?
a. They do not detect common aneuploidies.
b. They have higher rates of miscarriage.
c. They lack sufficient clinical validation studies.
d. They are invasive and require tissue sampling.
c. They lack sufficient clinical validation studies.
Explanation: Expanded NIPT panels can detect rare conditions, but their clinical utility is limited by a lack of large-scale validation studies. This limits their routine use in practice.
Aneuploidies are chromosomal abnormalities where there is an abnormal number of chromosomes, such as missing or extra copies.
Examples:
Trisomy 21 (Down syndrome): An extra copy of chromosome 21.
Trisomy 18 (Edwards syndrome): An extra copy of chromosome 18.
Trisomy 13 (Patau syndrome): An extra copy of chromosome 13.
Monosomy X (Turner syndrome): Missing one X chromosome in females.
A, B, D - wrong because it is non-invase thus can not sample for aneuplides or effect the fetus and it’s supporting structures
Genetic Screening
* Screening for fetal aneuploidy offered:
* First trimester: 10–14 weeks.
* Second trimester: 15–20 weeks.
* Cell-free DNA screening anytime after 10 weeks.
* Carrier screening for cystic fibrosis, spinal muscular atrophy, and
others.
Why is ultrasound guidance essential for both CVS and amniocentesis?
a. It reduces procedure time.
b. It ensures the correct placental location or uterine cavity is accessed.
c. It replaces the need for RhoGAM administration in Rh-negative patients.
d. It identifies neural tube defects during the procedure.
**Correct Answer: b. It ensures the correct placental location or uterine cavity is accessed.
Explanation: Ultrasound guidance helps accurately position the catheter or needle, minimizing risks like sampling the wrong tissue or causing complications.**
What is the role of third-trimester amniocentesis?
a. Detecting aneuploidy in low-risk pregnancies.
b. Assessing fetal lung maturity.
c. Diagnosing neural tube defects.
d. Determining fetal karyotype.
**Correct Answer: b. Assessing fetal lung maturity.
Explanation: Third-trimester amniocentesis is used to assess fetal lung maturity in cases where early delivery is anticipated, such as with preeclampsia or maternal health concerns.**
Why does early amniotic fluid sampling affect fetal lung development?
Amniotic fluid sampled too early may increase risks of complications but doesn’t directly impair lung development. Instead:
Rupture or leakage: Can lead to oligohydramnios (low fluid levels), which restricts fetal movement and lung expansion. This may result in pulmonary hypoplasia (underdeveloped lungs).
Infection: Early puncture of the amniotic sac raises the risk of infection, which could impact fetal growth.
Why is lung maturity tested in the third trimester?
Third Trimester Timing:
Fetal lungs produce surfactant (a substance that reduces surface tension in the lungs) late in pregnancy, typically after 32–34 weeks.
Measuring surfactant levels (like lecithin/sphingomyelin ratio) helps predict if the lungs can support breathing if preterm delivery is necessary.
Why might patients with multiple gestations undergo CVS?
a. To determine fetal sex in twin pregnancies.
b. To evaluate the karyotypes of individual fetuses.
c. To assess fetal lung maturity.
d. To avoid isoimmunization risks.
**Correct Answer: b. To evaluate the karyotypes of individual fetuses.
Explanation: In multiple gestations, CVS can provide karyotype information for each fetus, guiding decisions like selective reduction if abnormalities are detected.**
a. Detecting aneuploidy in low-risk pregnancies:
Involves using NIPT, CVS, or amniocentesis. NIPT is a non-invasive option but requires confirmatory testing (CVS or amniocentesis) for abnormal results.
b. Assessing fetal lung maturity:
Only performed with third-trimester amniocentesis. Doctors measure surfactant levels in the amniotic fluid to determine if the fetal lungs are developed enough for preterm delivery
What complication is more common with early amniocentesis (13–15 weeks) compared to traditional timing (15–22 weeks)?
a. Fetal lung immaturity
b. Miscarriage due to neural tube perforation
c. Membrane tenting and amniotic fluid leakage
d. Rh isoimmunization
**Correct Answer: c. Membrane tenting and amniotic fluid leakage
Explanation: Early amniocentesis has higher risks of complications like membrane tenting, amniotic fluid leakage, and clubfoot, making it less commonly performed.**
Membrane Tenting Definition:
During early amniocentesis, the needle insertion may create a vacuum-like effect, unintentionally lifting the amniotic sac (“drawing it upward”) toward the needle.
This increases the likelihood of puncture or tearing of the sac, leading to complications like fluid leakage.
Why it occurs more in early amniocentesis:
Before 15 weeks: The sac is thinner and less elastic, and less resilient making it more vulnerable to mechanical stress. The amount of amniotic fluid is smaller, making the membrane more susceptible to being pulled or pierced.
After 15 weeks: The sac thickens and adheres more closely to the uterine wall, reducing the risk of tenting.
The amniotic sac, which encloses the fetus and amniotic fluid, may become “drawn up” or tented if it sticks to the uterine wall or the needle during early amniocentesis (13–15 weeks). This can make the sac less flexible and more prone to tearing.
Why It’s Risky:
When the membrane is tented, it increases the risk of:
Amniotic Fluid Leakage: A tear in the membrane can lead to fluid escaping, which is critical for fetal development.
Miscarriage: Fluid loss or damage to the membrane can threaten the pregnancy.
Preventive Measures:
To reduce the risk of membrane tenting:
Use ultrasound guidance: Ensures precise needle placement.
Avoid early amniocentesis: Delaying until at least 15 weeks allows the amniotic sac to strengthen and the fluid volume to increase.
Experienced Operators: Skilled clinicians can minimize the likelihood of complications.
why does this happen if amniocentesis is done week 13-15: * Higher risks of membrane tenting, amniotic fluid leakage, and clubfoot.
When amniocentesis is performed between 13 to 15 weeks of pregnancy, there are higher risks of membrane tenting, amniotic fluid leakage, and clubfoot due to a combination of factors related to the developmental stage of the pregnancy and the characteristics of the amniotic sac and the uterus at this early stage. Here’s why:
- Membrane Tenting
What it is: Membrane tenting refers to when the needle used in amniocentesis unintentionally “draws up” or lifts the amniotic sac (the membrane surrounding the baby) during needle insertion.
Why it happens at 13-15 weeks:
At this early stage, the amniotic sac is still more pliable and less resilient compared to later stages of pregnancy when it is more firmly anchored in the uterus.
The amniotic sac is smaller and less filled with fluid, making it more prone to being distorted or drawn upwards when the needle enters.
This increases the risk of puncturing the sac, leading to amniotic fluid leakage and potential complications like premature rupture of membranes (PROM). - Amniotic Fluid Leakage
What it is: Leakage of amniotic fluid occurs when the needle punctures the amniotic sac during the procedure.
Why it happens at 13-15 weeks:
Early-stage amniocentesis (13–15 weeks) carries a higher risk of puncturing the sac because the tissues are less developed and the sac is not as well established as it would be later in pregnancy.
The amount of amniotic fluid is smaller at this stage, meaning less cushioning around the fetus, and a greater chance that the needle might damage the sac and cause leakage.
When fluid leaks out, it can result in complications, including increased risk of infection, premature labor, and in some cases, a miscarriage. - Clubfoot (or Other Malformations)
What it is: Clubfoot is a birth defect where a baby’s foot is turned inward, making walking difficult or impossible without correction.
Why it happens in early amniocentesis:
The risk of clubfoot increases with early amniocentesis because the amniotic sac is less developed and the fetus has less room to move.
When the needle is inserted into the sac, it can interfere with the space available for the fetus to move freely, and if the needle or the procedure is not handled carefully, it can lead to damage to the fetal development. This damage may affect the way the limbs, including the feet, develop.
Clubfoot may also result from other complications related to early amniocentesis, such as infection or inflammation, which may disrupt normal fetal development.
Why these risks decrease after 15 weeks:
After 15 weeks, the amniotic sac has expanded, the uterus has grown, and the fetus has more room to move. The amniotic sac becomes more firmly attached to the uterine wall and less prone to distortion. Therefore, the risk of puncturing the sac or causing damage is reduced.
Additionally, by 16-18 weeks, the amount of amniotic fluid is higher, providing better cushioning around the fetus and further reducing the likelihood of membrane tenting or fluid leakage.
In summary, performing amniocentesis earlier (13-15 weeks) increases the risks of complications due to the less-developed nature of the fetal membranes, smaller amount of amniotic fluid, and the less established relationship between the sac and uterus. These factors make the procedure riskier, which is why early amniocentesis is performed less frequently nowadays.
When is human chorionic gonadotropin (hCG) first detectable in serum after conception?
A) 1–3 days after conception
B) 6–12 days after conception
C) 20–22 days after the last menstrual period (LMP)
D) 10–12 weeks of gestation
Correct Answer: B) 6–12 days after conception.
Explanation: hCG is detectable in serum 6–12 days after conception and slightly later in urine.
a) Why It’s Wrong: hCG is not detectable that soon after conception. It takes several days for hCG to rise to detectable levels
C) Why It’s Wrong: While hCG levels can be detected around this time, the question asks about serum detection after conception, which is typically 6–12 days post-conception.
D) This is when HcG levels peak
Which pregnancy test detects hCG in the first voided morning urine?
A) Urine Pregnancy Test
B) Home Pregnancy Test
C) Serum Pregnancy Test
D) Both A and B
Correct Answer: B) Home Pregnancy Test.
Explanation: Home pregnancy tests are qualitative and detect hCG in the first voided morning urine. Urine tests in the office (e.g., urine pregnancy test) can also detect hCG but are typically used in a clinical setting.
A) Urine Pregnancy Test.
Why It’s Wrong: While urine tests are commonly used for pregnancy detection, this answer is too broad. “First voided morning urine” is more specifically tied to home pregnancy tests due to higher hCG concentration in the morning.
What It’s Good For: This answer covers general urine pregnancy tests, which are also used in-office but may not always require first-morning urine.
C) Serum Pregnancy Test.
Why It’s Wrong: Serum pregnancy tests are performed in a lab setting and detect hCG in blood, not urine, so they do not involve the first-morning void.
What It’s Good For: This describes a different diagnostic method that detects hCG earlier and quantitatively, useful in specific clinical scenarios like monitoring pregnancy complications.
C) What It’s Good For: Serum tests are more accurate and provide a quantitative hCG level, useful for assessing complications like ectopic pregnancy or abortion, but do not rely on morning urine.
D) Both A and B.
Why It’s Wrong: While both urine and home pregnancy tests detect hCG, the focus on “first voided morning urine” is specific to home tests for greater sensitivity.
What It’s Good For: This might confuse the overlapping functions of different hCG tests but inaccurately attributes morning specificity to both.
What is the main use of a quantitative serum β-hCG test?
A) To detect pregnancy in the first few days.
B) To evaluate threatened abortion, ectopic pregnancy, or molar pregnancy.
C) To measure the amount of amniotic fluid.
D) To assess fetal heart rate.
Correct Answer: B) To evaluate threatened abortion, ectopic pregnancy, or molar pregnancy.
Explanation: A quantitative serum β-hCG test can be used to assess early pregnancy complications, such as threatened abortion, ectopic pregnancy, or molar pregnancy. It is detectable 5–7 days after conception.
C) What It’s Good For: Amniotic fluid measurements are done through ultrasound, not hCG tests.
D) hCG testing does not provide information about fetal heart rate. This is measured by ultrasound or Doppler monitoring.
Threatened Abortion:
Vaginal bleeding before 20 weeks of gestation with a closed cervical os and no expulsion of products of conception.
The pregnancy is still viable, but there is a risk of progression to miscarriage.
Ectopic Pregnancy:
Implantation of the fertilized egg outside the uterine cavity, commonly in the fallopian tube.
Can cause life-threatening hemorrhage if not promptly diagnosed and treated.
Molar Pregnancy (Gestational Trophoblastic Disease):
Abnormal proliferation of trophoblastic tissue, often resulting in a non-viable pregnancy.
Characterized by abnormally high β-hCG levels and often a “snowstorm” appearance on ultrasound.
At what point during pregnancy do hCG levels peak?
A) 1–3 weeks of gestation
B) 6–8 weeks of gestation
C) 10–12 weeks of gestation
D) 15–18 weeks of gestation
Correct Answer: C) 10–12 weeks of gestation.
Explanation: hCG levels peak at 10–12 weeks of gestation and then decrease.
Which of the following is true about urine pregnancy tests?
A) They are more sensitive than serum pregnancy tests.
B) They provide a quantitative measurement of β-hCG.
C) They are typically used for initial pregnancy testing in office settings.
D) They require several days after conception to detect hCG.
Correct Answer: C) They are typically used for initial pregnancy testing in office settings.
Explanation: Urine pregnancy tests are commonly used in-office for initial pregnancy screening and use an antibody assay for β-hCG detection, providing quick results.
A) They are more sensitive than serum pregnancy tests.
Why It’s Wrong: Serum tests are more sensitive and can detect lower levels of hCG earlier than urine tests.
What It’s Good For: This could reflect an understanding of general hCG detection but incorrectly attributes greater sensitivity to urine tests.
B) They provide a quantitative measurement of β-hCG.
Why It’s Wrong: Urine tests are qualitative, indicating presence or absence of hCG, not its concentration.
What It’s Good For: This describes a feature of serum β-hCG tests but misapplies it to urine testing.
D) They require several days after conception to detect hCG.
Why It’s Wrong: While true, the focus of the question is on the clinical setting, not general detection timing.
What It’s Good For: This emphasizes the delayed detection window of urine tests compared to serum tests but misses the specific clinical application.
What does “G3 T1 P1 A0 L2” signify in a patient’s obstetric history?
A) 3 pregnancies, 1 term delivery, 1 preterm delivery, no abortions, and 2 living children.
B) 3 pregnancies, 1 preterm delivery, no term deliveries, and 2 living children.
C) 3 pregnancies, no term or preterm deliveries, and 2 abortions.
D) 3 pregnancies, 2 term deliveries, and no living children.
Correct Answer: A
Explanation:
“G3” = Total of 3 pregnancies.
“T1” = 1 pregnancy carried to term (≥37 weeks).
“P1” = 1 preterm delivery (20–36 weeks).
“A0” = No abortions (spontaneous or elective before 20 weeks).
“L2” = 2 living children.
B is incorrect because it misrepresents term and preterm deliveries.
C is incorrect because it indicates abortions that aren’t in the history.
D is incorrect because it wrongly suggests two term deliveries and no living children.
Which of the following laboratory findings is consistent with a molar pregnancy?
A) Low β-hCG levels for gestational age.
B) High β-hCG levels for gestational age.
C) Normal β-hCG levels with no abnormalities.
D) Undetectable β-hCG levels.
Correct Answer: B
Explanation:
Molar pregnancy is associated with abnormally high β-hCG levels due to trophoblastic overgrowth.
Abnormal proliferation of trophoblastic tissue, often resulting in a non-viable pregnancy.
Characterized by abnormally high β-hCG levels and often a “snowstorm” appearance on ultrasound.
A is incorrect because β-hCG levels are elevated, not low.
C is incorrect because the hallmark of molar pregnancy is abnormal hormone production.
D is incorrect because β-hCG is not undetectable; it is excessively high.
Which symptom is most concerning for ectopic pregnancy?
A) Painless vaginal bleeding with a closed cervical os.
B) Severe abdominal pain with shoulder tip pain and hemodynamic instability.
C) Regular uterine contractions at 37 weeks of gestation.
D) Mild nausea and fatigue during early pregnancy.
Correct Answer: B
Explanation:
Severe abdominal pain, shoulder tip pain (referred pain from diaphragmatic irritation due to hemoperitoneum), and hemodynamic instability suggest ruptured ectopic pregnancy.
Hemoperitoneum is the presence of blood in the peritoneal cavity.
A is incorrect because this describes threatened abortion.
C is incorrect because it describes labor at term.
D is incorrect because mild nausea and fatigue are normal pregnancy symptoms.
Which finding on an ultrasound would raise suspicion for a molar pregnancy?
A) Gestational sac with fetal pole and cardiac activity.
B) Empty uterus with an adnexal mass.
C) “Snowstorm” pattern without evidence of fetal development.
D) Multiple gestational sacs.
Correct Answer: C
Explanation:
The “snowstorm” pattern on ultrasound is characteristic of molar pregnancy due to trophoblastic proliferation.
A is incorrect because it represents a normal pregnancy.
B is incorrect because it describes ectopic pregnancy.
D is incorrect because multiple sacs suggest a multifetal pregnancy, not molar pregnancy.
What would be some causes of bleeding to occur in the first trimester of pregnancy?
Implantation Bleeding: Light spotting occurs as the fertilized egg implants into the uterine lining.
Threatened Abortion: Vaginal bleeding occurs, but the cervix remains closed, and the pregnancy is still viable.
Ectopic Pregnancy: Bleeding and pain occur when the embryo implants outside the uterine cavity, commonly in the fallopian tube.
Molar Pregnancy: Abnormal trophoblastic growth leads to bleeding with elevated β-hCG levels.
Subchorionic Hemorrhage: Bleeding between the chorion (outer fetal membrane) and the uterine wall.
Spontaneous Abortion: Pregnancy loss before 20 weeks, often with heavy bleeding and passage of tissue.
Non-Obstetric Causes: Cervicitis, vaginal infections, or cervical polyps.
Which of the following is NOT a common sign or symptom of an ectopic pregnancy?
A) Shoulder pain
B) Abdominal or pelvic pain, often localized to one side
C) Vomiting without nausea
D) Syncope or presyncope (lightheadedness or fainting)
C) Vomiting without nausea
Correct Answer: While nausea and vomiting can occur with ectopic pregnancy, vomiting without nausea is not a typical symptom. Nausea often accompanies the pain and other symptoms.
A) Shoulder pain
Wrong: Shoulder pain is a common sign of ectopic pregnancy due to diaphragmatic irritation from hemoperitoneum (blood in the abdomen). The phrenic nerve, which innervates the diaphragm, originates primarily from the C3, C4, and C5 nerve roots. Here’s why this connection is important:
C3, C4, C5 – “C3, 4, 5 keeps the diaphragm alive” is a common mnemonic that highlights how these nerve roots contribute to the function of the diaphragm (for breathing).
C4 and C5 nerve roots – These roots also contribute to the shoulder via the brachial plexus, which innervates muscles like the deltoid (for shoulder abduction, which is controlled by C5) and the trapezius (which helps with shoulder shrugging, controlled by C4).
Since the phrenic nerve is closely related to the nerve roots for the shoulder (C4/C5), referred pain from diaphragmatic irritation (such as in the case of an ectopic pregnancy with hemoperitoneum) can be felt in the shoulder. This phenomenon is called referred shoulder pain, typically on the right side, because of the shared neural pathways.
In summary:
The C4 and C5 nerve roots contribute to both diaphragmatic function (via the phrenic nerve) and shoulder movements (via the brachial plexus).
Referred shoulder pain in conditions like ectopic pregnancy occurs due to the diaphragm’s nerve connections with the shoulder region. This is why pain from diaphragmatic irritation (hemoperitoneum) is often felt as shoulder pain, particularly in the right shoulder.
B) Abdominal or pelvic pain, often localized to one side
Wrong: This is a classic symptom of an ectopic pregnancy. The pain usually starts as colicky and may become generalized if the pregnancy ruptures.
D) Syncope or presyncope (lightheadedness or fainting)
Wrong: Syncope (fainting) or presyncope (lightheadedness) can occur in cases of ectopic pregnancy due to significant blood loss or shock, especially in the event of a rupture.
What is the main difference between surgical management and medical management of ectopic pregnancy?
A) Surgical management is for stable patients, while medical management is for unstable patients.
B) Surgical management is indicated for unstable patients or those with contraindications to medical treatment.
C) Medical management always requires laparoscopic surgery.
D) Surgical management is only performed in cases of early pregnancy loss.
B) Surgical management is indicated for unstable patients or those with contraindications to medical treatment.
Correct Answer: This is true. Surgical management is preferred for patients with unstable vitals or in cases where medical management (e.g., methotrexate) is contraindicated or has failed.
A) Surgical management is for stable patients, while medical management is for unstable patients.
Wrong: This is incorrect. Surgical management is typically used for unstable patients or when medical management is not an option or has failed. Medical management is used for stable patients.
C) Medical management always requires laparoscopic surgery.
Wrong: Medical management, such as methotrexate, does not require surgery. It is a non-surgical approach for stable patients.
D) Surgical management is only performed in cases of early pregnancy loss.
Wrong: Surgical management is specifically for cases of ectopic pregnancy, not general early pregnancy loss. It is used when the pregnancy has ruptured or when medical treatment is ineffective.
What is the primary medical treatment for hemodynamically stable patients with ectopic pregnancy?
A) Antibiotics
B) Methotrexate
C) Salpingectomy
D) Hormone therapy
B) Methotrexate
Correct Answer: Methotrexate is the first-line medical treatment for stable patients with an ectopic pregnancy. It stops the growth of the pregnancy tissue and is effective for resolving the pregnancy in certain cases.
A) Antibiotics
Wrong: Antibiotics are used for infections but are not the primary treatment for ectopic pregnancy. Methotrexate is the key medication used for non-ruptured, hemodynamically stable ectopic pregnancies.
C) Salpingectomy
Wrong: Salpingectomy is a surgical procedure to remove the fallopian tube and is typically used when the patient is unstable or when medical treatment has failed.
D) Hormone therapy
Wrong: Hormone therapy is not a primary treatment for ectopic pregnancy. Methotrexate, a chemotherapy agent, is used to treat ectopic pregnancies in stable patients.
What is Fetal Fibronectin (fFN) Test: Purpose & Interpretation
The fetal fibronectin (fFN) test is a diagnostic tool used to assess the risk of preterm labor in pregnant individuals between 22 and 34 weeks gestation. It measures the presence of fetal fibronectin, a glycoprotein found in the cervicovaginal secretions, which acts like a “biological glue” between the fetal membranes and the uterus.
Why Is the fFN Test Important?
Normally, fetal fibronectin is present early in pregnancy and again near term (around 37 weeks), when the body prepares for labor.
If fFN is detected before 34 weeks, it suggests disruption of the fetal-maternal interface, which may indicate an increased risk of preterm labor.
How Is the Test Performed?
A cervicovaginal swab is collected during a speculum exam.
The sample is analyzed for the presence of fetal fibronectin.
Important Considerations:
The test should be done before a digital cervical exam or vaginal ultrasound, as these can disrupt the cervix and give a false-positive result.
Avoid intercourse, vaginal exams, or lubricants for 24 hours before the test to prevent contamination.
Why Is a Negative Test More Useful?
A negative fFN test is very reassuring because it strongly predicts that delivery is unlikely in the next two weeks.
This helps avoid unnecessary hospitalizations, interventions, and medications for false alarms.
Limitations of the fFN Test
A positive result does NOT confirm preterm labor—it only indicates an increased risk.
Can be falsely positive due to recent sexual activity, vaginal exams, or infections.
Less useful after 34 weeks because fFN naturally increases as labor approaches.
