Healthy parturients presenting for scheduled cesarean delivery will have blood drawn and
measured for microparticles at baseline, immediately after delivery, and at several time
Protocol: Informed consent will be obtained and documented. Subjects who agree to
participate will have an intravenous line of at least 16 gauge placed by an anesthesiologist
via standard sterile technique, and lidocaine will be used for patient comfort during the
procedure. The intravenous line will contain two stopcocks and will be connected to
intravenous fluids as ordered by the obstetrician or anesthesiologist for patient care. If
for any reason the intravenous line cannot be used for blood draws, a second intravenous
line will be placed for the purpose of drawing blood samples. This line will be placed by an
anesthesiologist who uses lidocaine and operates under standard sterile conditions. This
line will not be connected to fluids, but to a device with a short piece of tubing used
commonly for this purpose (often called a "heplock," although no heparin is used); two
stopcocks will be attached to the end of this device.
Blood samples will be drawn through the intravenous line (or the "heplock" when it becomes
necessary to place one) using the following procedure: a 10 mL sterile syringe will be
attached to the distal stopcock and 5 mL of blood will be withdrawn (to clear the line of
intravenous fluids). A second 10 mL sterile syringe will be attached to the proximal
stopcock and 5 mL blood will be withdrawn for assay (total 10 mL blood withdrawn). The blood
withdrawn to clear the line will be wasted. Finally, a 5 mL normal saline flush will be
administered to clear the line of blood.
Blood will be drawn at baseline (placement of intravenous catheter), immediately after
delivery of the placenta (within 15 minutes), 1 hour postpartum (within 1 hour and 1 hour 15
minutes), 4 hours postpartum (within 4 hours and 4 hours 15 minutes), and 24-36 hours
postpartum (5 samples total per subject). After the last blood draw, the intravenous line
will be discontinued if clinically indicated.
Blood will be placed in a standard "yellow top" tube and sent to the University's flow
cytometry lab where it will be centrifuged and will undergo flow cytometry to measure
microparticles and staining to identify endothelial-, platelet- versus leukocyte-derived
microparticles and to determine placental origin. In addition Tissue Factor levels in the
microparticles will be measured. Also, confirmatory image stream microscopy will be
performed. Data acquisition will be performed on the ImageStreamX with validation on the
Demographic data collected will include age, height, weight, American Society of
Anesthesiologists Physical Status Classification, gravidity, parity, estimated gestational
age, and co-existing maternal or obstetric conditions. Note will be made of the date and
time of each blood draw, and date and time of delivery of the baby and the placenta.
Estimated blood loss will be recorded, as will blood product transfusion.
Sample size: As this is pilot data, a convenience sample of 10 patients will be studied.
Statistics: Demographic data will be presented primarily with descriptive statistics.
Comparisons will be made for each assay result among the various time points (i.e., baseline
values compared to values at subsequent times). Tests for normality will be performed; mean
and standard deviation will be reported for normal data and median with interquartile range
for non-normal data. Assay results at various time points will be compared with a
mixed-model analysis of variance. A P < 0.05 will be required to reject the null hypothesis.
- All patients with a singleton pregnancy with gestational age greater than or equal to
36 weeks who present for scheduled cesarean delivery will be eligible for
- Specific exclusion criteria include emergency cesarean delivery, labor pain,
hypertensive diseases of pregnancy, diabetes, known placental abnormalities such as
placental abruption, placenta previa and placenta accreta, and known disorders of
coagulation or recent anticoagulant therapy.