A 28-year-old woman, gravida 1 para 0, at 41 weeks gestation comes to the hospital for antepartum fetal surveillance. She has had less fetal movement than usual but no abdominal pain, leakage of fluid, or vaginal bleeding. Blood pressure is 120/80 mm Hg. The patient's pre-pregnancy BMI was 40 kg/m², and she has gained 20 kg (44 lb) during the pregnancy. Her pregnancy has otherwise been uncomplicated. Nonstress test shows a baseline fetal heart rate of 140/min, moderate variability, and no accelerations for 40 minutes. Two contractions are observed on the tocodynamometer. An episode of fetal heart rate decrease to 130/min began after the peak of a contraction and lasted for a minute. Ultrasound shows a fetus in cephalic presentation, a loop of umbilical cord near the fetal neck, an estimated fetal weight at the 35th percentile for gestational age, and a single deepest pocket of amniotic fluid of 1 cm. The biophysical profile results are shown below. Which of the following is the most likely cause of this patient's biophysical profile results?

Question

A 28-year-old woman, gravida 1 para 0, at 41 weeks gestation comes to the hospital for antepartum fetal surveillance. She has had less fetal movement than usual but no abdominal pain, leakage of fluid, or vaginal bleeding. Blood pressure is 120/80 mm Hg. The patient's pre-pregnancy BMI was 40 kg/m², and she has gained 20 kg (44 lb) during the pregnancy. Her pregnancy has otherwise been uncomplicated. Nonstress test shows a baseline fetal heart rate of 140/min, moderate variability, and no accelerations for >40 minutes. Two contractions are observed on the tocodynamometer. An episode of fetal heart rate decrease to 130/min began after the peak of a contraction and lasted for a minute. Ultrasound shows a fetus in cephalic presentation, a loop of umbilical cord near the fetal neck, an estimated fetal weight at the 35th percentile for gestational age, and a single deepest pocket of amniotic fluid of 1 cm. The biophysical profile results are shown below. Which of the following is the most likely cause of this patient's biophysical profile results?

Quizplus · Accepted Answer

11ec25c8_da69_65cd_bc81_55e929060994_MD0003_00 Decreased placental function is typically due to increased placental vascular resistance caused by age-related placental changes in late-term pregnancies (≥41 weeks gestation). Decreased placental function reduces placental perfusion during contractions, which can result in intermittent fetal hypoxemia. On nonstress test, intermittent hypoxemia presents as late decelerations, fetal heart rate decelerations that gradually nadir after the peak of a contraction. late decelerations Progressive placental dysfunction can lead to chronic fetal hypoxemia (ie, uteroplacental insufficiency), which causes central nervous system suppression and possible fetal demise. To prevent this suppression, blood is preferentially distributed to the brain rather than peripheral tissue, resulting in decreased fetal activity (eg, movement, breathing, muscle tone). In the fetal kidney, the decreased renal perfusion and urine production result in oligohydramnios (single deepest pocket of amniotic fluid <2 cm). A biophysical profile (BPP), performed in patients at risk for uteroplacental insufficiency, includes a nonstress test and ultrasound assessment of amniotic fluid volume and fetal activity. Each BPP component is scored 0 or 2 and summed to a total score of 0-10. Normal BPP scores (8 or 10) exclude fetal hypoxemia. Chronic hypoxemia from uteroplacental insufficiency causes an abnormal BPP (particularly ≤4) and suggests imminent risk of fetal demise, and delivery is typically indicated. (Choice A) Fetal head compression can cause a physiologic parasympathetic response that presents as early decelerations, gradual heart rate decelerations that nadir at the peak of the contraction. Head compression does not result in hypoxemia and therefore does not cause an abnormal BPP. early decelerations (Choice B) Fetal sleep cycles can cause a nonreactive nonstress test (ie, no accelerations due to lack of movement); sleep cycles do not cause late decelerations or oligohydramnios. (Choice C) Intraamniotic infection (chorioamnionitis) can present with oligohydramnios if associated with premature rupture of membranes (not seen in this patient). Fetal monitoring indicates tachycardia (>160/min). (Choice D) Nuchal cords are associated with variable decelerations, abrupt (≥15/min) decreases in fetal heart rate below the baseline of varying depth and duration. Nuchal cords do not cause oligohydramnios or decreased fetal breathing movements. variable decelerations (Choice E) Polyhydramnios, an amniotic fluid index ≥24 cm or a single deepest pocket ≥8 cm, does not affect the BPP score. Educational objective: A biophysical profile (BPP) is performed in patients at risk for uteroplacental insufficiency (eg, ≥41 weeks gestation). Chronic hypoxemia causes an abnormal BPP and suggests imminent risk of fetal demise; in such cases, delivery is typically indicated. References: Practice bulletin no. 146: management of late-term and postterm pregnancies. (http://www.ncbi.nlm.nih.gov/pubmed/25050770) Fetal movements as a predictor of health. (http://www.ncbi.nlm.nih.gov/pubmed/27374723)

A 28-Year-Old Woman, Gravida 1 Para 0, at 41 Weeks