Physiological Integrity Q 25
As the client reaches 8 cm dilation, the nurse notes late decelerations on the fetal monitor. The FHR baseline is 165–175 bpm with variability of 0–2bpm. What is the most likely explanation of this pattern?
A. The baby is asleep.
B. The umbilical cord is compressed.
C. There is a vagal response.
D. There is uteroplacental insufficiency.
Correct Answer: D. There is uteroplacental insufficiency.
This information indicates a late deceleration. This type of deceleration is caused by uteroplacental lack of oxygen. Late decelerations are one of the precarious decelerations among the three types of fetal heart rate decelerations during labor. They are caused by decreased blood flow to the placenta and can signify an impending fetal acidemia.
Option A: Has no relation to the readings. The primary etiology of a late declaration is found to be uteroplacental insufficiency. Decreased blood flow to the placenta causes a reduced amount of blood and oxygen to the fetus.
Option B: Compressed umbilical cord results in a variable deceleration. The central pathophysiology behind late deceleration involves uterine contraction constricting blood vessels in the wall of the uterus which decreases blood flow through the intervillous space of the placenta, reducing diffusion of oxygen into fetal capillaries causing decreased fetal PO2.
Option C: A vagal response is indicative of an early deceleration. When fetal PO2 decreases, chemoreceptors initiate an autonomic response in the fetus causing intense vasoconstriction with increased blood pressure. The elevated blood pressure is perceived by the baroreceptors which ultimately stimulate the parasympathetic system to decrease the fetal heart rate, causing late deceleration.