Electronic Fetal Monitoring Subspecialty – Rationale Samples

Question

Following an ultrasound which revealed decreased amniotic fluid, a woman at term is admitted in early labor. It should be recognized that oligohydramnios often results in fetal heart rate decelerations that are

  • late in onset or occur after the peak of the contraction
  • synchronous with that of the contraction
  • varied in depth and duration

Rationale

Oligohydramnios, diagnosed on fetal ultrasound is associated with increased morbidity and includes increased incidences of meconium-stained amniotic fluid and cesarean section for fetal indications. Other associations include low Apgar scores, and umbilical artery pH values as well as umbilical cord compression leading to variable decelerations.

Question

In comparing early and late decelerations, a distinguishing factor between the two is

  • onset time to the nadir of the deceleration
  • the number of decelerations that occur
  • timing in relation to contractions

Rationale

In early decelerations, the onset, nadir and recovery of the deceleration occur at the same time as the beginning, peak and end of the uterine contraction respectively. In late decelerations, the onset, nadir and recovery of the deceleration occur after the beginning, peak and ending of the uterine contraction respectively. In comparing the two types of decelerations, timing in relation to the contraction is the distinguishing factor.

Question

A baroceptor response to an increase in arterial blood pressure is to

  • cause vasoconstriction of the veins
  • increase respiratory rate
  • slow the down the heart rate

Rationale

When arterial pressure increases, the baroreceptors which respond to changes in the blood pressure against vessel walls, will start to slow the heart rate. This causes vasodilatation not vasoconstriction. Respiratory rate changes usually are controlled by responses of the chemoreceptors that respond to changes in the environmental chemical make up.

EFM Graph

Question

This fetal heart rate pattern is most appropriately characterized as

  • marked variability
  • misapplied fetal spiral electrode
  • pseudosinsoidal

Rationale

The pattern shown here represents marked variability (greater than 25 beats per minute). If the fetus were acidotic, a more ominous pattern would be evident such as recurrent late decelerations. Stadol administration often causes a false sinusoidual (pseudosinusoidal) or flat baseline pattern.