Abstract
Objective
This study aimed to evaluate the feasibility of randomizing patients to weight-based
low molecular weight heparin (LMWH) versus no pharmacologic thromboprophylaxis following
cesarean delivery (CD).
Study Design
Single-center, open-label pilot randomized controlled trial of individuals aged 18+
undergoing CD at the University of Utah Health from November 2023 to June 2024. Those
with a contraindication to anticoagulation, a plan for therapeutic anticoagulation,
or considered at highest risk for postpartum venous thromboembolism (VTE; i.e., undergoing
cesarean-hysterectomy, high-risk thrombophilia, personal history of thromboembolism)
were excluded. Enrolled individuals were randomized in a 1:1 ratio utilizing block
randomization with randomly varying block sizes to receive weight-based LMWH for 14
days or no pharmacologic thromboprophylaxis. The primary outcome was feasibility,
defined as ≥35% enrollment of eligible individuals and retention of ≥85% of enrolled
individuals through all study procedures. Secondary feasibility outcomes included
the number of eligible patients per month, approach rate, enrollment rate, and retention
rate. Additional outcomes included VTE, wound hematoma, patient-reported symptoms,
or a bleeding complication within 6 weeks postpartum. Baseline characteristics were
compared between those approached and enrolled and those not enrolled. The proportion
meeting each of the outcomes was reported with 95% confidence intervals (CI).
Results
Over the 6-month study period, 694 patients were screened and found eligible for an
average of 106 eligible patients per month. There were 611 patients approached (88%,
95% CI: 85.6–90.5), of which 64 enrolled (10.5%, 95% CI: 8–12.9), and 61 participants
were retained through all study procedures (95.3%, 95% CI: 90–100). Thus, the overall
primary outcome feasibility parameters were not met. Among the 64 individuals enrolled
and randomized, the mean age was 31.0 years (standard deviation: 5.5 years), and the
majority were non-Hispanic White (56%). Baseline characteristics were similar between
those who were approached and enrolled compared with those not enrolled. There were
no differences in additional clinical outcomes (VTE, wound hematoma, patient-reported
symptoms, or bleeding complications) by prophylaxis group.
Conclusion
In this pilot trial, individual patient randomization to weight-based LMWH or no pharmacologic
thromboprophylaxis after CD was not feasible due to low enrollment rates. Future trials
addressing postpartum thromboembolism prevention should consider alternative study
designs.
Key Points
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Individual patient randomization to enoxaparin or no therapy after CD was not feasible.
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The approach rate, enrollment rate, and retention rate were 88, 11, and 95%, respectively,
in this single-center pilot.
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Future prospective studies may need to consider alternative designs.
Keywords
enoxaparin - feasibility - pilot trial - thromboprophylaxis - VTE
