FETAL WELLBEING

Overview of the Lecture

  • The lecture discusses prenatal testing methods, specifically focusing on genetic testing and monitoring fetal health through procedures such as chorionic villus sampling (CVS) and amniocentesis.

Chorionic Villus Sampling (CVS)

  • Definition: Chorionic villus sampling (CVS) involves taking a small piece of tissue from the placenta (chorionic villi) for testing.

  • Timing: Typically conducted between 10 to 12 weeks of pregnancy.

  • Procedure:

    • Invasive procedure done vaginally with abdominal ultrasound assistance.

    • A probe is inserted vaginally to locate the products of conception.

  • Purposes:

    • Diagnosing chromosomal abnormalities.

    • Genetic and DNA studies to detect potential issues early in pregnancy.

  • Benefits:

    • Faster results compared to other methods (e.g., amniocentesis).

    • Can determine the sex of the baby and check for chromosomal abnormalities.

  • Risks:

    • Linked to limb reduction birth defects if done before 10 weeks.

    • Possible spontaneous abortion or miscarriage; cannot detect neural tube defects.

Amniocentesis

  • Definition: Amniocentesis is a medical procedure where a needle is inserted into the uterus to obtain amniotic fluid for testing.

  • Timing: Usually performed around 14 weeks to 36-38 weeks of pregnancy.

  • Purposes:

    • Detects chromosomal and genetic abnormalities.

    • Assesses lung maturity (measured with L/S ratio) in later pregnancy.

  • Risks:

    • Potential for labor induction or miscarriage.

  • Procedure:

    • An ultrasound is used to guide the needle to avoid the umbilical cord and ensure safe collection of fluid.

Genetic Considerations

  • Chromosomes Measurement:

    • Normal chromosomal count is 46 (23 pairs).

    • Condition called Trisomy 21 (Down syndrome) is indicated by an extra chromosome on the 21st pair.

    • The existing chromosome pairs are 44 (22 pairs) plus the unique sex chromosomes (XX or XY).

  • Non-compatible with life:

    • Extra chromosome on pairs 15 and below is often fatal.

  • Alpha-fetoprotein Test:

    • Conducted between 15 to 20 weeks of pregnancy.

    • Measures levels of a protein produced by the fetal liver.

    • High levels may indicate potential issues like open spinal, abdominal wall defects (e.g., gastroschisis).

    • This test is not definitive and requires further testing if abnormalities are noted.

Ultrasound Techniques

  • Transabdominal Ultrasound:

    • Requires a full bladder to lift the uterus for clearer imaging.

  • Transvaginal Ultrasound:

    • Provides clearer images, especially in early pregnancy (under 12 weeks).

    • Useful for determining fetal position and assessing growth.

  • Clinical Applications:

    • Identify pregnancy and gestational age.

    • Monitor fetal well-being and movements.

    • Detect fetal anomalies (facial abnormalities, etc.).

    • Accompany procedures like amniocentesis.

Fetal Monitoring

  • Fetal Movement Monitoring:

    • Starts at 28 weeks; reduced movement may indicate issues (fetal hypoxia or growth restriction).

  • Kick Count:

    • Important for prenatal monitoring—10 movements in three hours is an indicator of good fetal health.

  • Factors Affecting Movement:

    • Hypoglycemia, maternal psychological state, smoking, drugs, etc.

Measurement Techniques

  • McDonald's Rule:

    • Measures the fundal height (from pubic symphysis to top of uterus) in centimeters correlating with gestational weeks.

  • Non-Stress Test (NST):

    • Evaluates fetal heart rate in response to movement.

    • Ideal fetal baseline around 140 beats per minute; accelerations indicate health.

    • Required parameters: two accelerations within a 20-minute window, where acceleration is an increase by at least 15 beats lasting 15 seconds.

Biophysical Profile

  • Purpose:

    • Assesses the well-being of the fetus incorporating five variables via ultrasound.

  • Variables Measured:

    • Fetal movement, breathing, tone, heart rate activity, amniotic fluid volume.

  • Results Interpretation:

    • Scoring ranges from 8-10 (normal), 6 (suspicious), and 4 (potential fetal distress).

Contraction Stress Test

  • Purpose:

    • Evaluates placental function and fetal response to contractions potentially induced by Pitocin.

  • Risks:

    • Time-consuming with possible false positives.

  • Definition of Normal:

    • Fetal heart rate and contraction patterns should not show late decelerations.

Conclusion

  • Final Q&A:

    • Invitation for questions from the audience at the end of the lecture.

  • Encouragement for further discussion or clarification on the presented topics.