Screening Tests in Pregnancy — MCQs
Test done at sub-centre during pregnancy:
A woman presents with painless ulcers on the vulva, she gives a history of having multiple sexual partners and has had a stillbirth at 28 weeks in the past. What is the next best step of investigation?
What are the criteria for administering Anti-D immunoglobulin postpartum in an Rh-negative female?
Nuchal translucency in USG can be detected at_____weeks of gestation.
Most appropriate time for chorionic villus sampling in pregnancy is:
Which of the following represents the current recommendation for offering screening for Down's syndrome during pregnancy?
What is the preferred timing for routine urine sample collection in a pregnant female?
Most accurate method to confirm viable intrauterine pregnancy at 6 weeks' gestation is
A 7-week pregnant lady underwent a chest X-ray by mistake. What is to be done?
A 7 weeks pregnant lady has 1 accidental exposure to x-ray. Which of the following should be done?
Screening Tests in Pregnancy Indian Medical PG Practice Questions and MCQs
Question 1: Test done at sub-centre during pregnancy:
- A. Haemoglobin (Correct Answer)
- B. Triple test
- C. USG
- D. OGTT
Explanation: ***Haemoglobin*** - **Haemoglobin testing** is a routine and essential screening measure performed at the subcenter level during pregnancy, primarily to detect and monitor **anaemia**. - Its simplicity, cost-effectiveness, and direct impact on maternal and fetal health make it suitable for primary healthcare settings. *Triple test* - The **triple test** (or multiple marker screen) is a prenatal diagnostic test for chromosomal abnormalities and neural tube defects, typically performed between weeks 15 and 20 of pregnancy. - This test requires specialized laboratory facilities and interpretation, which are usually not available or routinely performed at the subcenter level. *USG* - **Ultrasonography (USG)** is a vital imaging technique used to monitor fetal growth, development, and maternal health during pregnancy. - While crucial, USG requires specialized equipment and trained personnel (sonographers or radiologists) and is generally conducted in higher-level healthcare facilities, not routinely at a subcenter. *OGTT* - An **Oral Glucose Tolerance Test (OGTT)** is used to screen for **gestational diabetes mellitus**. - While it is a routine test in pregnancy, performing a full OGTT (which involves multiple blood draws over several hours after glucose ingestion) is often logistically challenging for routine performance at a subcenter; usually, only initial screening (like random blood sugar or fasting glucose) or a single-step glucose challenge test might be done at a primary level before referral.
Question 2: A woman presents with painless ulcers on the vulva, she gives a history of having multiple sexual partners and has had a stillbirth at 28 weeks in the past. What is the next best step of investigation?
- A. PCR
- B. VDRL (Correct Answer)
- C. Vaginal swab and culture
- D. NAT
Explanation: ***VDRL*** - The presentation of **painless vulvar ulcers**, a history of **multiple sexual partners**, and a past **stillbirth at 28 weeks** are highly suggestive of **syphilis**. - A **VDRL (Venereal Disease Research Laboratory) test** is a non-treponemal serologic test used for screening and monitoring the treatment of syphilis. *PCR* - While **PCR** can be used to detect the genetic material of *Treponema pallidum*, it is not the primary diagnostic test for syphilis, especially given the classic clinical picture. - It is more commonly used for detecting other sexually transmitted infections (STIs) or for specific situations where direct detection of the organism from a lesion is preferred. *Vaginal swab and culture* - A **vaginal swab and culture** would be appropriate for diagnosing bacterial vaginosis, candidiasis, or certain bacterial STIs, but it is not suitable for diagnosing syphilis. - Syphilis is caused by a spirochete (*Treponema pallidum*) that cannot be cultured on standard media. *NAT* - **Nucleic Acid Amplification Tests (NATs)** are a broad category of tests that include PCR. - Like PCR, while potentially applicable for *Treponema pallidum* detection, they are not the standard or first-line diagnostic investigation for syphilis given the strong clinical indicators.
Question 3: What are the criteria for administering Anti-D immunoglobulin postpartum in an Rh-negative female?
- A. DCT positive, Baby Rh +ve
- B. DCT negative, Baby Rh +ve (Correct Answer)
- C. DCT negative, Baby Rh -ve
- D. DCT positive, Baby Rh -ve
Explanation: ***DCT negative, Baby Rh +ve*** * The mother is **Rh-negative** and needs Anti-D immunoglobulin if her baby is **Rh-positive** to prevent sensitization. * A **negative Direct Coombs Test (DCT)** indicates that the mother has not yet developed antibodies against the baby's Rh-positive red blood cells, making Anti-D administration effective for prevention. * *DCT positive, Baby Rh +ve* * If the **DCT is positive**, it means the mother has already formed **antibodies** against the baby's Rh-positive red blood cells (sensitization has occurred). * In this scenario, administering Anti-D immunoglobulin would be **ineffective** as the immune response has already begun. * *DCT negative, Baby Rh -ve* * If the baby is **Rh-negative**, there is no risk of Rh sensitization for an Rh-negative mother. * Therefore, **Anti-D immunoglobulin is not necessary** in this situation. * *DCT positive, Baby Rh -ve* * A **positive DCT** in an Rh-negative mother implies sensitization has occurred, but it would not be due to an Rh-negative baby. * Administering Anti-D immunoglobulin would be **ineffective** and unnecessary if the baby is Rh-negative.
Question 4: Nuchal translucency in USG can be detected at_____weeks of gestation.
- A. 11-13 weeks (Correct Answer)
- B. 18-20 weeks
- C. 8-10 weeks
- D. 20-22 weeks
Explanation: ***11-13 weeks*** - Nuchal translucency (NT) is a **first-trimester ultrasound marker** used for screening for chromosomal abnormalities like **Down syndrome**. - The optimal window for accurate measurement is between **11 weeks 0 days and 13 weeks 6 days** of gestation, or when the crown-rump length (CRL) is between 45 mm and 84 mm. *18-20 weeks* - This period is typically dedicated to the **anomaly scan** or **mid-pregnancy scan**, which focuses on detecting structural abnormalities in the fetus. - While other markers like **nuchal fold thickness** can be assessed later, the diagnostic value of Nuchal Translucency is decreased by this time. *8-10 weeks* - At this early stage, the fetus is generally **too small** for accurate and consistent measurement of the nuchal translucency. - The nuchal translucency itself might not be fully developed or easily distinguishable for precise measurement. *20-22 weeks* - By this gestational age, the **nuchal translucency has usually resolved** or is no longer a reliable marker for chromosomal screening. - This period is well beyond the recommended window for NT measurement, making it unsuitable for this specific screening test.
Question 5: Most appropriate time for chorionic villus sampling in pregnancy is:
- A. 16-18 weeks
- B. 16-20 weeks
- C. 8-10 weeks
- D. 10-13 weeks (Correct Answer)
Explanation: ***10-13 weeks*** - Chorionic villus sampling (CVS) is optimally performed between **10 and 13 completed weeks of gestation**. - This timing allows for **earlier diagnosis** of chromosomal abnormalities compared to amniocentesis, enabling more time for decision-making. *16-18 weeks* - This timeframe is typically used for **amniocentesis**, which is performed later in pregnancy. - Performing CVS at this stage is **outside the optimal window** and carries a higher risk profile for CVS specifically. *16-20 weeks* - This period is also generally recommended for **amniocentesis**, not chorionic villus sampling. - Delaying CVS until this point **reduces the advantage** of early diagnosis and may increase procedural risks. *8-10 weeks* - Performing CVS **before 10 weeks of gestation** is associated with a **higher risk of limb reduction defects** in the fetus. - Due to this significant risk, CVS is generally **contraindicated** before 10 weeks.
Question 6: Which of the following represents the current recommendation for offering screening for Down's syndrome during pregnancy?
- A. 35
- B. No screening necessary
- C. 30
- D. All in the reproductive age group (Correct Answer)
Explanation: ***All in the reproductive age group*** - The American College of Obstetricians and Gynecologists (ACOG) and other major medical bodies recommend that **all pregnant women**, regardless of age, be offered **screening for Down syndrome** and other aneuploidies. - This recommendation reflects the principle of **patient autonomy** and the availability of safe and effective screening methods for all pregnancies, not just those considered high-risk based on maternal age. *30* - While the risk of Down syndrome increases with maternal age, **screening is not exclusively recommended for women aged 30**; rather, it is offered to all pregnant women. - Focusing only on this age group would **miss cases** in younger women and limit informed decision-making. *35* - Historically, **maternal age 35** was considered the threshold for offering invasive diagnostic testing due to the significantly increased risk of Down syndrome. - However, current guidelines emphasize universal screening, as a substantial number of babies with Down syndrome are born to women **younger than 35** due to higher birth rates in this group. *No screening necessary* - This option is incorrect as **screening is routinely offered** to all pregnant women to provide information about the risk of conditions like Down syndrome. - Deciding to forgo screening or diagnostic testing is a personal choice, but the **option to screen should always be available** to the patient.
Question 7: What is the preferred timing for routine urine sample collection in a pregnant female?
- A. Early morning sample (Correct Answer)
- B. Suprapubic puncture
- C. Mid-stream collection
- D. Catheterization
Explanation: ***Early morning sample*** - An **early morning urine sample** is preferred because it is the most concentrated, increasing the likelihood of detecting abnormalities. - This concentration allows for accurate assessment of substances like **blood cells**, **protein**, and **bacteria**, which might be diluted in samples collected later in the day. *Mid-stream collection* - **Mid-stream collection** aims to reduce contamination from the periurethral area but does not provide the same concentration as an early morning sample. - While important for reducing contaminants, it's not the primary factor determining the optimal collection time for diagnosing pregnancy-related conditions. *Suprapubic puncture* - **Suprapubic puncture** is an invasive procedure generally reserved for situations where a clean catch is impossible or contamination is a significant concern, typically in infants or critically ill patients. - It carries risks such as **pain**, **hematuria**, and potential **bowel perforation**, making it unsuitable for routine urine collection in pregnant women. *Catheterization* - **Catheterization** is an invasive method that carries a risk of introducing infection into the bladder. - It is usually performed only when a clean-catch sample cannot be obtained or when precise measurement of residual urine is necessary, not for routine screening in pregnant women.
Question 8: Most accurate method to confirm viable intrauterine pregnancy at 6 weeks' gestation is
- A. USG fetal cardiac activity (Correct Answer)
- B. Clinical examination
- C. Urine HCG test
- D. Doppler ultrasound in specific clinical situations
Explanation: **USG fetal cardiac activity** - At 6 weeks' gestation, the presence of **fetal cardiac activity** on ultrasound is the definitive sign of a **viable intrauterine pregnancy**. - This finding confirms both the presence of an embryo and its vital status, providing direct evidence of viability. *Urine HCG test* - A **urine HCG test** confirms the presence of pregnancy but does not provide information about its viability or location (intrauterine vs. ectopic). - High HCG levels can be present even in non-viable or ectopic pregnancies. *Clinical examination* - A **clinical examination** may reveal signs consistent with pregnancy, such as an enlarged uterus, but it cannot definitively confirm **intrauterine location** or **fetal viability** at 6 weeks' gestation. - These findings are supportive but not diagnostic of viability. *Doppler ultrasound in specific clinical situations* - Doppler ultrasound is typically used to assess **blood flow** to various structures and may be useful in later pregnancy for assessing fetal well-being or placental function. - It is not the primary or most accurate method to confirm early **fetal cardiac activity** or viability at 6 weeks' gestation compared to standard grayscale ultrasound.
Question 9: A 7-week pregnant lady underwent a chest X-ray by mistake. What is to be done?
- A. Terminate the pregnancy immediately due to radiation exposure.
- B. Perform chromosomal testing to assess fetal damage.
- C. Reassure the patient and continue the pregnancy. (Correct Answer)
- D. Conduct prenatal invasive diagnostic tests to evaluate fetal health.
Explanation: **Reassure the patient and continue the pregnancy.** - A single chest X-ray delivers a **negligible dose of radiation (around 0.01 mGy)** to the embryo/fetus, which is significantly below the threshold for causing congenital abnormalities or pregnancy loss. - The **teratogenic threshold** for radiation exposure is generally considered to be around **50-100 mGy**, making a single chest X-ray exposure well within safe limits. *Terminate the pregnancy immediately due to radiation exposure.* - There is **no clinical justification** for pregnancy termination based on a single chest X-ray, as the radiation dose is far too low to cause significant harm. - Such an intervention would be based on **misinformation** and could lead to unnecessary emotional distress and ethical concerns. *Perform chromosomal testing to assess fetal damage.* - Chromosomal testing is **not indicated** for low-dose radiation exposure from a single chest X-ray, as this type of exposure is unlikely to cause chromosomal abnormalities. - The radiation dose is simply too low to inflict the kind of damage that would necessitate such invasive and often risky procedures. *Conduct prenatal invasive diagnostic tests to evaluate fetal health.* - Invasive prenatal diagnostic tests, such as **amniocentesis or chorionic villus sampling**, carry their own risks and are not warranted for a benign exposure like a chest X-ray. - These tests are typically reserved for situations with a much higher established risk of fetal anomalies.
Question 10: A 7 weeks pregnant lady has 1 accidental exposure to x-ray. Which of the following should be done?
- A. Continue the pregnancy with monitoring (Correct Answer)
- B. Perform chromosome analysis if needed
- C. Conduct pre-invasive diagnostic testing if indicated
- D. Consider termination of pregnancy
Explanation: ***Continue the pregnancy with monitoring*** - The risk of **fetal malformation** and **intellectual disability** from a single diagnostic X-ray exposure is generally considered very low, often below the threshold for clinical concern. - Current guidelines typically recommend continuing pregnancy with routine monitoring unless the estimated fetal dose exceeds a certain threshold (e.g., 50-100 mGy), which is unlikely with a single accidental exposure. *Perform chromosome analysis if needed* - **Chromosome analysis** is generally reserved for cases with suspected genetic anomalies or significant fetal exposure to radiation at doses known to induce chromosomal damage. - A single, accidental X-ray exposure is unlikely to cause clinically significant chromosomal aberrations requiring such invasive testing. *Conduct pre-invasive diagnostic testing if indicated* - **Pre-invasive diagnostic testing**, such as nuchal translucency scans or maternal serum screening, assesses risks for common aneuploidies and neural tube defects, not typically direct radiation effects. - While these tests are part of routine prenatal care, a single X-ray exposure does not, by itself, create a specific indication for additional pre-invasive testing beyond standard recommendations. *Consider termination of pregnancy* - **Termination of pregnancy** is usually considered only in cases of significant, confirmed fetal harm or very high radiation doses that unequivocally increase the risk of severe birth defects or intellectual disability. - A single accidental X-ray exposure almost certainly does not meet this threshold, as the associated risks to the fetus are minimal.
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