SCIENTIFIC
Delayed Complete Chorioamniotic Membrane Separation in the Third Trimester Following a Motor Vehicle Collision
AUTHORS : Katherine R . Addicott , MD
Jesse N . Cottrell , MD
Marshall University Joan C . Edwards School of Medicine Department of Obstetrics and Gynecology
CASE
A 20-year-old gravida-2-para-0 at 32 weeks gestation presented to the emergency department ( ED ) after she was an unrestrained passenger in a motor vehicle collision ( MVC ). The driver had lost control of the vehicle , which subsequently rolled down an embankment . Upon presentation to the ED , the patient reported lower leg pain and uterine contractions . She was found to have multiple abrasions on her lower extremities . After a trauma assessment was completed and the patient was determined to be stable , she was admitted to the labor and delivery floor for maternal and fetal monitoring . Laboratory tests to evaluate for placental abruption revealed a positive fetal cell stain and a fibrinogen level of 456mg / dL . During her hospital stay , fibrinogen levels ranged from 384mg / dL to 519mg / dL . She was Rhesus factor positive and Rhogam was not indicated . Given the presence of abdominal tenderness that developed after admission and a steady decline in her hemoglobin level from 9.5g / dL to 7.5g / dL over three days , the patient was presumed to have a placental abruption , and two units of packed red blood cells were transfused . The patient ’ s past medical history was significant for a bicornuate uterus ; the current gestation was noted to be in the left horn . She had an ultrasound completed at admission that showed a biophysical profile of 8 / 8 with a normal appearing placenta and polyhydramnios . A repeat ultrasound 48 hours later remained reassuring with no abnormalities demonstrated . Throughout the hospital course , fetal heart rate monitoring was reassuring , and there were no placental or fetal abnormalities appreciated during fetal ultrasonography . The pa-
ABSTRACT
tient was discharged on hospital day four at her request .
Nine days post MVC at 33 weeks and three days gestation , the patient underwent follow-up ultrasonography and antenatal fetal testing as further monitoring due to the placental abruption diagnosed during her inpatient admission . By patient report and on physical examination , the patient was asymptomatic and had no abnormalities . The ultrasound revealed a complete chorioamniotic separation ( CAS ) as depicted in Images 1 and 2 . Consultation was obtained with a maternal-fetal medicine specialist who recommended admission for inpatient care . Laboratory studies upon this admission were as follows : fibrinogen level of 567mg / dL , and hemoglobin and hematocrit levels of 11.3g / dL and 33.7 %, respectively . Due to the risk of adverse maternal and fetal outcomes , a low transverse cesarean section was performed via a Pfannenstiel incision . A defect in the anterior portion of the left horn was discovered where the placenta had been located . The umbilical cord appeared to be 90 % detached from the placenta . The placenta was sent for pathological examination , which revealed a subchorionic hemorrhage and unremarkable placenta parenchyma and membranes . The patient was discharged on hospital day four after an unremarkable hospital stay . The neonate was admitted to the neonatal intensive care unit and was discharged to home at 28 days of life in good condition .
DISCUSSION
Complete separation of the amnion and chorion in the third trimester is a rarely described pregnancy complication . Chorioamnionotic separation primarily occurs by
Complete separation of the amnion and chorion is a rare pregnancy complication . The proposed causes for chorioamniotic separation are failure of fusion , spontaneous separation , and iatrogenically from invasive prenatal procedures . We present the first reported case of delayed complete chorioamniotic separation following a motor vehicle collision . Close follow-up with serial fetal ultrasounds resulted in a favorable outcome .
failure of fusion , spontaneous separation , or as an iatrogenic complication of trauma to the membranes following an invasive prenatal procedure . 1 Many of the cases involving failure of fusion are also strongly associated with fetal aneuploidy or a fetal connective tissue disorder . 2 To our knowledge , the occurrence of CAS following maternal trauma by MVC has not previously been described .
In early embryological development , the amnion arises from extra-embryonic tissue and the chorion is formed by the trophoblast and somatic mesoderm . As pregnancy progresses , these layers fuse between 14 to 16 weeks gestation . Separation of these two membranes after 16 weeks is uncommon , and the incidence is approximately 1 in 3,400 . 1 Chorioamnionotic separation can result in serious pregnancy morbidity , with the primary adverse outcomes being preterm delivery , premature rupture of membranes , intrauterine growth restriction , and stillbirth . 3 Other complications associated with CAS include amniotic band syndrome . 4 Due to the maternal and perinatal risk in those diagnosed with CAS , follow-up can range from sonographic estimation of fetal growth every four weeks during the second trimester to twice-weekly biophysical profiles during the third trimester .
A retrospective cohort study by Bibbo et al . found that the rate of preterm delivery in patients with CAS was significantly higher ( 57.5 % vs 17.1 %, p < 0.01 ) when matched with those without CAS . 3 The study was comprised of slightly over 100 women with CAS and did not find any significant differences in growth restriction , stillbirth , or fetal demise between the two groups . However , the same study
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