A 28-year-old woman, gravida 1 para 0, at 37 weeks gestation comes to labor and delivery for induction of labor for severe polyhydramnios. The patient's 20-week anatomy ultrasound showed a male fetus with a tracheoesophageal fistula and a posterior fundal placenta. She developed increasingly severe polyhydramnios, with her most recent amniotic fluid index measuring 39 cm (normal:

Question

A 28-year-old woman, gravida 1 para 0, at 37 weeks gestation comes to labor and delivery for induction of labor for severe polyhydramnios.  The patient's 20-week anatomy ultrasound showed a male fetus with a tracheoesophageal fistula and a posterior fundal placenta.  She developed increasingly severe polyhydramnios, with her most recent amniotic fluid index measuring 39 cm (normal: <24).  The patient has been receiving an oxytocin infusion and is having painful contractions every 3 minutes with a category 1 fetal heart rate tracing.  She has a sudden gush of copious clear amniotic fluid immediately followed by heavy vaginal bleeding and constant abdominal pain.  Temperature is 36.7 C (98 F), blood pressure is 130/80 mm Hg, and pulse is 118/min.  Fetal heart rate tracing shows a baseline of 120/min and minimal variability.  Tocodynamometer shows contractions every minute.  The uterus is smooth, gravid, and tender to palpation.  The cervix is 5 cm dilated and 100% effaced with the fetal vertex at +1 station.  Which of the following is the most likely cause of this patient's acute presentation?

Quizplus · Accepted Answer

11ec25c8_da1a_d110_bc81_df46da453179_MD0003_00 This laboring patient with sudden-onset heavy vaginal bleeding and abdominal pain immediately after rupture of membranes has abruptio placentae, the premature detachment of the placenta from the uterus due to bleeding at the uteroplacental interface. Patients with uterine overdistension (eg, twin gestation, severe polyhydramnios) are at increased risk for abruptio placentae because the sudden, uncontrolled loss of amniotic fluid causes rapid uterine decompression, which shears maternal placental vessels and causes placental hemorrhage and separation. The bleeding also increases intrauterine pressure, which causes constant pain, a rigid, tender uterus, and uterine irritability (ie, high-frequency contractions). As more of the placenta detaches, fetal perfusion progressively declines and can lead to hypoxia. Therefore, patients with persistent bleeding and an abnormal fetal heart rate tracing (eg, bradycardia, minimal variability) require urgent delivery to prevent fetal demise and maternal complications (eg, hemorrhage, disseminated intravascular coagulation). (Choice B) Normal labor progression is characterized by contractions that cause cervical dilation and often spontaneous rupture of membranes; however, it would not cause acute onset of pain and minimal variability. (Choice C) Placenta accreta, the attachment of placental villi directly onto myometrium (usually over a prior uterine scar), causes postpartum, not intrapartum, hemorrhage due to the inability to remove the placenta after fetal delivery. Placenta accreta (Choice D) Umbilical cord prolapse can occur in patients with polyhydramnios and uncontrolled rupture of membranes. Although it may cause abnormalities on the fetal heart rate tracing, cord prolapse does not cause abdominal pain or increased bleeding. Umbilical cord prolapse (Choice E) Uterine rupture, a full-thickness uterine wall defect, can cause acute pain, vaginal bleeding, and abnormalities on the fetal heart rate tracing. Although the risk is increased in patients with uterine overdistension and those undergoing oxytocin induction, uterine rupture rarely occurs in primigravid patients without prior uterine surgery (eg, cesarean delivery). In addition, this patient has a smooth uterus, making this diagnosis less likely. Uterine rupture (Choice F) Vasa previa, fetal placental vessels overlying the cervix, can present with vaginal bleeding immediately after rupture of membranes due to injury to fetal vessels; however, bleeding is typically painless. Vasa previa Educational objective: Abruptio placentae is the premature separation of the placenta from the uterus prior to fetal delivery and typically presents with abdominal pain, vaginal bleeding, high-frequency uterine contractions, and abnormalities on the fetal heart rate tracing. Uterine overdistension (eg, twin gestation, severe polyhydramnios) is a risk factor. References: Placental abruption: epidemiology, risk factors and consequences. (http://www.ncbi.nlm.nih.gov/pubmed/21241259)

A 28-Year-Old Woman, Gravida 1 Para 0, at 37 Weeks