Venous Thromboembolism (VTE) Risk Assessment & Prophylaxis In Irish Hospitalized Obstetric Patients: A Nationwide Cross-Sectional Study

Pulmonary embolism continues to be the second leading cause of mortality in pregnancy and the puerperium. VTE complicates 1 - 2/1000 pregnancies, and the risk increases with age, mode of delivery, and presence of co-morbidities. Literature has shown that the use of low molecular weight heparin (LMWH) is safe in this patient cohort.

Assessment of the prevalence of VTE risk in hospitalised women in both the antenatal and postnatal groups to determine the proportion of at-risk patients who receive LMWH prophylaxis appropriately.

The study period was September 2011 to November 2012. All inpatients in the participating hospitals on the day of investigation were assessed for risk of VTE on the basis of hospital chart review. Risk profile was assessed in accordance with the 2009 Royal College of Obstetricians and Gynaecologist Guidelines. Patients undergoing procedures or on the labour ward at the time of review were excluded. Ethical approval was obtained from the ethics committees governing all centres.

610 pregnancies were reviewed across 19 centres. The average age of was 31+/- 5.65yrs (Range 16-47), with 21.87% aged over 35. 22% had a parity of 3 or more. The average weight was 71.51kg (Range 42-134kg, SD 14.482kg). Data on BMI was available for 77% - 34% were overweight and 21% were obese. 1% had a BMI>40. 31% were antenatal and 69% were postnatal.

63% of antenatal patients were low risk (<2 risk factors), 35% were intermediate risk (2 or more risk factors, prophylaxis should be considered) and 2% were high risk. All the high risk patients were on prophylaxis at an appropriate dose. 4% of the low risk patients were on prophylaxis unnecessarily. Only 7% of the intermediate risk patients were on correctly dosed prophylaxis.

Among postnatal patients, 41% were low risk (<2 risk factors), 58% were intermediate risk (2 or more risk factors, require prophylaxis) and <1% were high risk. 80% were appropriately risk stratified and put on LMWH if necessary. 59% of patients should have been on LMWH but only 42% were (92% Tinzaparin and 8% Enoxoparin). This included 8 patients who were on LMWH unnecessarily. 38% were on too low a dose.

VTE prophylaxis remains a central issue in obstetric care given its prominent role in maternal morbidity and mortality and the increasing prevalence of risk factors such as obesity and increasing maternal age. It is clear that while there is good awareness of the risk in the postnatal period, there is less emphasis on risk assessment in antenatal patients where prophylaxis is rarely used. Those on prophylaxis are also likely to be on an incorrect dose. There is a clear role for a national guideline to standardize care for all pregnant women. On the basis of these findings, we have authored a guideline and this is now in use as a reference in all Irish maternity units.

No relevant conflicts of interest to declare.