When pregnant patients are diagnosed by their physician as being at risk for VTE, or when
they enter the perinatology practice on a previously-prescribed prophylactic enoxaparin
regimen, they will be offered a chance to discuss participation in the study. The patient
will be consented and those who are not already receiving enoxaparin will be prescribed one
of the two dosing regimens, at their physician's discretion, at that same clinic visit.
A baseline blood sample will be drawn to assess coagulation using thromboelastography [TEG].
TEG is a point-of-care device which measures the viscoelastic properties of clot formation.
This device can provide rapid and detailed information about coagulation changes. TEG will be
used to assess coagulation changes after commencing treatment with enoxaparin (see later).
As per routine care, the patient will be instructed by the clinic nurse on how to fill her
prescription at the pharmacy, how to give herself the injection subcutaneously once daily in
the morning, and how to troubleshoot the injection process. As per routine care, the patient
will have the opportunity to ask all questions necessary about this process, and her
understanding and ability to comply with the injection procedures will be assessed by the
clinic RN. The patient will be given a new prescription as needed by her physician at her
regularly scheduled MD appointment. At any time, as per routine care, the patient can have
the opportunity to review or troubleshoot the injection process with the RN or MD in the
clinic. At each clinic visit, as per routine care, approximately 1-2 times per month as per
routine care, the patient will be weighed and her weight recorded in her prenatal chart. At
each of these visits the patient will also be asked a series of questions as per the study
flowsheet in the chart, about potential side effects or adverse events she may have
experienced since her last visit. In addition, she will receive a phone call from one of the
study investigators once to twice per month to enquire about side effects, medication
tolerability, and medication compliance. At 3 predetermined intervals throughout the
pregnancy, the patient will be instructed to give a blood sample at the outpatient
laboratory. When at all possible, these blood draws will be coordinated to coincide with the
patient's regularly scheduled prenatal care blood draws, to minimize venipuncture episodes.
The study blood sample results will test for: anti-Xa level , which is a marker of the
effective prophylactic range of Enoxaparin, serum creatinine, which is a marker of kidney
function and renal clearance of medication, and also for coagulation analysis (using TEG) to
assess the coagulation effects of enoxaparin. TEG is a point-of-care device which measures
the viscoelastic properties of clot formation. This device can provide rapid and detailed
information about coagulation changes. The anti-XA level sample results will be blinded to
the medical care providers and to the patient, and used for research purposes only. At or
shortly after the patient reaches 36 weeks gestation, she will be switched from enoxaparin to
unfractionated heparin (UFH), as per standard of care to avoid any potentially unexpected
bleeding events associated with the onset of labor at term. When the patient comes to the
hospital for Labor and Delivery, routine labor and delivery care will ensue at the discretion
of the medical care team. 24 hours after delivery, or at the discretion of the medical care
team, the patient will be restarted on her Enoxaparin dosing arm, as per standard of care.
She will be instructed to continue the enoxaparin for 6 weeks, and will receive a
prescription from the in-hospital providers for this. The patient will return for a 6 week
follow-up visit in the clinic as per standard of care, and a final study blood draw will be
performed at that time.
If the patient misses her 6 week appointment, she will receive a phone call to reschedule as
per standard of care, and will be instructed over the phone to discontinue her Enoxaparin and
to come in for a blood draw.