Surfactant appears in amniotic fluid at the gestational age of?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2021

Obstetrics & Gynaecology

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2021

Explanation

Surfactant, a substance crucial for lung function after birth, becomes detectable in the amniotic fluid around 28 weeks of gestation.
Its production by type II pneumocytes begins earlier (around 24 weeks), but it is secreted into the amniotic fluid through fetal breathing movements, becoming measurable around the 28-week mark.
The appearance of surfactant at 28 weeks is a key indicator of developing lung maturity and correlates with an increased chance of neonatal survival if born prematurely.
While present at 28 weeks, the amount is often insufficient for full lung function; mature levels are typically reached by 34–36 weeks.

Option A: This is too early. While the initial synthesis of surfactant by specialized lung cells (type II pneumocytes) begins around 20-24 weeks, it is not yet secreted into the amniotic fluid in detectable quantities.
Option C: This is incorrect because surfactant has already appeared in the amniotic fluid by this time. At 32 weeks, there is a significant surge in surfactant production, which greatly increases its concentration and contributes to further lung maturation.
Option D: This is incorrect as it marks the point of full lung maturity, not the initial appearance of surfactant. By 36 weeks, the lungs are generally considered mature, with sufficient surfactant levels to prevent Respiratory Distress Syndrome (RDS).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Fetal lung development and the timeline of surfactant production and appearance in amniotic fluid as background academic context rather than a clinical decision trigger.
A nurse's understanding of the surfactant timeline is crucial for managing preterm labor. Assessing surfactant levels in amniotic fluid (e.g., via the Lecithin/Sphingomyelin ratio) helps the healthcare team predict the risk of Neonatal Respiratory Distress Syndrome (RDS) and prepare for necessary interventions.
This knowledge is vital for patient education, as the nurse can explain to expectant parents why a preterm birth at 28 weeks carries risks for breathing problems and why certain treatments are initiated.
What if? If a mother presents in preterm labor at 29 weeks, the nurse would anticipate orders for antenatal corticosteroids (e.g., Betamethasone). This intervention helps accelerate fetal lung maturation and surfactant production, significantly reducing the risk and severity of RDS in the newborn.

How to Approach the Question

First, identify the core concept of the question, which is the timeline of fetal surfactant development.
Break down the keywords: 'Surfactant', 'appears', and 'amniotic fluid'. The word 'appears' is critical, as it asks for the point of detection, not the start of production or full maturity.
Recall the distinct stages of surfactant development: 1. Synthesis begins (20-24 weeks). 2. It appears in amniotic fluid (28 weeks). 3. A major surge in production occurs (32 weeks). 4. Full maturity is reached (36 weeks).
Evaluate each option against this timeline.
Option A (20 weeks) is when synthesis starts.
Option B (28 weeks) is when it becomes detectable in the amniotic fluid.

Concept Tested & Keywords

Concept Tested: Fetal lung development and the timeline of surfactant production and appearance in amniotic fluid.
Stem keywords: Surfactant, amniotic fluid, gestational age
Lead-in keywords: appears in

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E6 Obstetrics Williams pp. 20-36, 25-43