A nurse is teaching a client who is scheduled for an amniocentesis about the purpose of a lecithin/sphingomyelin ratio test.
Which of the following statements should the nurse make?

Choice A rationale

Administering oxygen via nasal cannula at 2 L/min might marginally increase fetal oxygenation, but it does not address the primary issue of hypotension causing decreased placental perfusion. The fundamental problem is reduced blood flow to the placenta, necessitating interventions that increase maternal circulating volume and blood pressure to improve perfusion.

Choice B rationale

Administering a lactated Ringer's 500 mL bolus directly addresses hypotension by expanding the maternal intravascular volume. This increased circulating volume raises blood pressure, thereby improving placental perfusion and oxygen delivery to the fetus. Lactated Ringer's is an isotonic solution, effective for rapid volume expansion.

Choice C rationale

Placing the client in a knee-chest position is typically used to alleviate cord compression or prolapse by shifting the fetus, not for treating hypotension. This position can actually worsen hypotension by trapping blood in the lower extremities and reducing venous return to the heart, further compromising placental blood flow.

Choice D rationale

Monitoring the client's blood pressure every 30 minutes is a crucial assessment but is not an immediate intervention for acute hypotension with decreased placental perfusion. While ongoing monitoring is essential, immediate actions are required to correct the underlying cause of hypotension and restore adequate blood flow to the placenta.

Abruptio Placentae: Typically does not cause increased contraction frequency; contractions may be normal or decreased due to uterine irritation or pain.

Uterine Tachysystole: Characterized by more than 5 contractions in 10 minutes averaged over 30 minutes, indicating excessive contraction frequency, which can reduce uteroplacental perfusion.

Uterine Tone
Abruptio Placentae: The uterus often becomes firm, rigid, and tender due to bleeding and inflammation caused by premature placental separation, increasing baseline uterine tone.

Uterine Tachysystole: Uterine tone is elevated because contractions are prolonged and close together, causing the uterus to remain tense with insufficient relaxation.

Pain Report
Abruptio Placentae: Patients usually report sharp, severe abdominal or back pain due to the sudden placental detachment and uterine irritation.

Uterine Tachysystole: Pain may be present but is typically related to frequent contractions rather than sharp, localized pain.

FHR Pattern
Abruptio Placentae: Commonly causes fetal heart rate abnormalities like late decelerations, bradycardia, or absent variability due to fetal hypoxia from compromised placental perfusion.

Uterine Tachysystole: Can cause decreased fetal heart rate variability and late decelerations because frequent contractions reduce oxygen delivery during inadequate relaxation.