Chorionic Villus Sampling (CVS) is usually performed at which gestational age?

JIPMER Nursing Officer-2024

Obstetrics & Gynaecology

Easy

Appeared in: JIPMER Nursing Officer-2024

Explanation

Chorionic Villus Sampling (CVS) is a prenatal diagnostic test performed in the first trimester to detect genetic and chromosomal abnormalities.
The standard, recommended window for performing CVS is between 10 and 13 weeks of gestation.
This timing provides the benefit of an early diagnosis, allowing parents more time to make informed decisions.
The 10-12 week option is the only choice that falls entirely within this safe and effective period.

Option A: Performing CVS this early is strongly contraindicated due to a significantly increased risk of causing fetal limb-reduction defects and oromandibular limb hypogenesis.
Option C: This is the standard timeframe for performing amniocentesis, a different prenatal diagnostic test that samples amniotic fluid.
Option D: This is too late for a standard CVS procedure. Diagnostic testing at this stage is typically performed via amniocentesis or percutaneous umbilical blood sampling (cordocentesis).

Visual 1: Diagram: Illustrating the transcervical and transabdominal routes for performing Chorionic Villus Sampling (CVS), showing the catheter or needle obtaining a sample from the placenta.
Visual 2: Timeline: A comparative timeline showing the optimal windows for major prenatal diagnostic tests, highlighting CVS (10-13 weeks) and Amniocentesis (15-20 weeks).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Optimal gestational age for Chorionic Villus Sampling (CVS) as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in patient education, ensuring expectant parents understand the specific timing, benefits, and risks associated with different prenatal tests like CVS and amniocentesis.
Accurate patient counseling is vital. A nurse must be able to explain why waiting until 10 weeks is critical for fetal safety before a CVS can be performed.
What if? A patient at 9 weeks gestation is highly anxious and demands a CVS immediately. The nurse's priority is to explain that performing the procedure before 10 weeks carries a significant risk of limb defects and that waiting one week is essential for the baby's safety.

How to Approach the Question

Identify the key concept in the question, which is the specific timing for the medical procedure 'Chorionic Villus Sampling (CVS)'.
Recall the standard guidelines for prenatal diagnostic testing, focusing on the different windows for first-trimester and second-trimester procedures.
Evaluate each option against the known safe and effective timeframe for CVS.
Eliminate the option that is too early (6-8 weeks) by remembering the associated risk of limb defects.
Eliminate the options that are too late (15-20 weeks and 20-24 weeks) by associating them with the timing for amniocentesis.
Select the option (10-12 weeks) that falls within the established safe window of 10-13 weeks for CVS.

Concept Tested & Keywords

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