Anticoagulant prescribing practices and anesthetic interventions among anticoagulated pregnant patients: a retrospective study

Induction or spontaneous labor for pregnant patients on anticoagulants?

OBJECTIVE

There are two approaches to peripartum management for pregnant patients undergoing anticoagulation treatments: spontaneous labor or scheduling an induction. A long interval without anticoagulation is a thrombosis risk factor, while a short interval leads to risks of delivery without epidural analgesia or post partum hemorrhage. Our objective was to evaluate the impact of planned induction versus spontaneous labor on obtaining neuraxial analgesia.

MATERIALS AND METHODS

A retrospective single-center study was conducted from 2012 to 2020 including all patients on preventive or curative low molecular-weight heparin at the time of delivery, excluding planned cesarean sections. The rates of neuraxial analgesia were compared between two groups: spontaneous labor and induction, as well as the intervals without anticoagulants.

RESULTS

127 patients were included. In the spontaneous labor group, 78% (44/56) received neuraxial analgesia versus 88% (37/42) in the induction group (p = 0.29). For curative dose treatment, the rate of neuraxial analgesia was 45,5% in the spontaneous group versus 78,6% (p = 0.12). The median time without anticoagulation was 34 h [26-46] in the spontaneous labor group and 43 h [34-54] in the induction group (p = 0.01), without an increased incidence of thrombosis. The rate of postpartum hemorrhage did not differ between the two groups.

CONCLUSION

Planned induction tended to increase the rate of neuraxial analgesia, without reaching significance, and most women in spontaneous labor accessed analgesia. Peripartum management should be a shared decision with the patient considering the obstetrical and thrombosis risk context for each patient.

Increased unfractionated heparin requirements with decreasing body mass index in pregnancy

BACKGROUND

Pregnant women receiving low-molecular-weight heparin for therapeutic anticoagulation are often converted to unfractionated heparin in anticipation of labor. We aim to characterize the impact of maternal body mass index on attainment of target anticoagulation during the conversion process.

METHODS

We conducted a five-year retrospective study of a pregnancy cohort converted from low-molecular-weight heparin to unfractionated heparin in the third trimester. Patient demographics, anticoagulation regimens, and clinical outcomes were extracted from the medical record. Nonparametric statistical methods were used for analysis by body mass index (<30, 30-35, and >35).

RESULTS

Thirty-one subjects were evenly distributed by body mass index (p = 0.97). Linear regression revealed an inverse correlation between patient body mass index and unfractionated heparin dose needed to achieve therapeutic anticoagulation (p = 0.04). Subjects with body mass index > 35 attained therapeutic activated partial thromboplastin time levels at 18 U (Units)/kg/h, while subjects with body mass index < 30 required 25 U/kg/h (p = 0.02).

CONCLUSION

Higher doses of unfractionated heparin are needed to achieve anticoagulation in patients with body mass index < 30 during pregnancy. This paradoxical relationship may be explained by physiologic characteristics that increase unfractionated heparin elimination, including diminished adiposity and increased renal clearance.