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A 27-year-old G1 P0000 woman presents to her doctor's office at 32–5/7 weeks’ gestation complaining of decreased fetal movement for the past 24 hours. Fetal monitoring in the office reveals a prolonged deceleration followed by an apparent sinusoidal pattern. The patient and her husband are sent immediately to the perinatal diagnostic center for a biophysical profile. The profile score is 2/10, which is associated with fetal compromise. In addition, Doppler studies show an increase in the peak velocity of systolic blood flow in the middle cerebral artery, which is consistent with fetal anemia. The prenatal course was normal up to this point and the past medical history was negative. The woman is transferred to labor and delivery for further evaluation and preparation for a cesarean section. On arrival to labor and delivery, EFM is begun (Fig. 1), and appropriate laboratory tests for surgery are ordered.
Findings on EFM Strip #1 are:
Baseline Rate: 150 beats/min
Episodic Pattern: None
Periodic Pattern: None noted
Uterine Contractions: Low-amplitude, frequent contractions
Interpretation: Category II: Indeterminate, which means that it is not predictive of abnormal fetal acid-base status
Differential Diagnosis: Fetal anemia possibly due to a placental abruption, fetal maternal hemorrhage, ruptured vasa previa, or hemolytic anemia
Action: The goal is to optimize blood flow to the uterus and improve oxygenation to the fetus. Potential interventions include maintaining continuous fetal monitoring, placing the mother in a lateral position, administering an intravenous bolus of lactated Ringer solution, and administering 100% oxygen per nonrebreather mask. Even though the baseline rate is within the normal range, the minimal variability and the biophysical score of 2/10 are very concerning. Loss of variability is more predictive of hypoxemia and acidemia in a preterm fetus compared with a term fetus. A preterm fetus also can progress much faster from a reassuring to nonreassuring FHR status than a term fetus (Freeman et al, 2003). A Kleihauer-Betke blood test is ordered to determine if fetal hemoglobin cells are present in the maternal bloodstream.
The noted actions are taken, and an immediate tracing is obtained (Fig. 2).
Findings on EFM Strip #2 are:
Variability: Initially moderate, then indeterminant
Baseline Rate: Initially 135 beats/min, then unable to determine due to development of a sinusoidal pattern
Episodic Pattern: Appears to be a deceleration but due to a 3-minute gap of missing data in the tracing, the type of deceleration cannot be determined
Periodic Pattern: None noted
Uterine Contractions: Irregular and mild by palpation
Interpretation: A sinusoidal pattern would be classified as a Category III FHR tracing, which means that it is predictive of abnormal fetal acid-base status at the time of observation
Differential Diagnosis: Fetal anemia of unknown cause. However, the presence of decreased fetal movement in conjunction with a sinusoidal pattern suggests that a fetomaternal hemorrhage may be the cause. In addition to fetal anemia, a true sinusoidal pattern is associated with hypoxia/asphyxia, fetal infection, and fetal cardiac anomalies. Whatever the pathology, a true sinusoidal pattern is a significant finding that implies fetal decompensation and requires immediate intervention.
Action: Proceed with plans to deliver the baby. Notify the neonatal intensive care staff and neonatologist of fetal status. Continue with all of the previous interventions.
The Kleihauer-Betke test is positive for fetal cells in the maternal bloodstream, which confirms a fetomaternal hemorrhage. Thirty minutes later, another tracing is obtained (Fig. 3).
Findings on EFM Strip #3 are:
Baseline Rate: 145 beats/min
Episodic Pattern: None noted
Periodic Pattern: None noted
Uterine Contractions: Every 2 minutes, lasting 40 to 60 seconds. Intensity and resting tone are obtained per palpation
Interpretation: Category II FHR
Actions: Despite the disappearance of the sinusoidal pattern and the presence of a normal baseline FHR, the continued minimal variability and concerning findings on diagnostic tests warrant an immediate delivery.
Forty-five minutes later, a pale viable male infant weighing 1,673 g is delivered by cesarean section. Apgar scores are 8 at 1 and 5 minutes. The baby is sent to the neonatal intensive care unit, where neonatal anemia is diagnosed. He ultimately does well. Pathologic examination of the placenta reveals numerous focal infarctions. A specimen for cord gases was drawn but was not sufficient for testing.