Fetal Oxygenation and Acid-Base Balance Flashcards
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What is the normal pH range for umbilical artery blood at delivery?
Answer: 7.25 – 7.35
A normal umbilical artery pH at delivery is 7.25–7.35, reflecting adequate fetal acid-base status.
Which type of acidosis is characterized by an elevated PCO2 and normal base deficit in fetal cord blood?
Answer: Respiratory acidosis
Respiratory acidosis results from acute CO2 accumulation (elevated PCO2) without significant base deficit, often due to transient cord compression.
The primary mechanism by which oxygen crosses the placenta from mother to fetus is:
Answer: Simple diffusion
Oxygen crosses the placental membrane via simple diffusion down a partial pressure gradient from maternal to fetal blood.
A base deficit greater than which value is considered significant for metabolic acidosis in the newborn?
Answer: 12 mmol/L
A base deficit greater than 12 mmol/L in umbilical artery blood is the threshold associated with significant metabolic acidosis and potential neonatal morbidity.
Which fetal blood vessel carries oxygenated blood FROM the placenta TO the fetus?
Answer: Umbilical vein
The umbilical vein carries oxygenated, nutrient-rich blood from the placenta to the fetus.
Fetal hypoxia is defined as:
Answer: Inadequate oxygen delivery to fetal tissues
Fetal hypoxia is defined as inadequate oxygen delivery to fetal tissues, which can lead to anaerobic metabolism and acidosis if prolonged.
In fetal cord blood gas analysis, which value best reflects fetal metabolic status?
Answer: Base deficit
Base deficit best reflects the degree of metabolic acidosis because it measures the amount of buffer (bicarbonate) consumed, independent of respiratory changes.