Recommendations

Society of Obstetric Medicine of Australia and New Zealand

Recommendations from the Society of Obstetric Medicine of Australia and New Zealand on testing for venous thromboembolism, inherited thrombophilia, proteinuria in established pre-eclampsia, and erythrocyte sedimentation rate (ESR) in pregnancy. The Society of Obstetric Medicine of Australia and New Zealand aims to advance clinical and scientific knowledge of hypertensive diseases and medical disorders in pregnancy and to foster collaboration with other regional and international societies interested in hypertension in pregnancy and obstetric medicine.

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3.
Do not undertake methylenetetrahydrofolate reductase (MTHFR) polymorphism testing as part of a routine evaluation for thrombophilia in pregnancy

Date reviewed: 25 September 2017

Patients with the thermolabile variant of the methylenetetrahydrofolate reductase (MTHFR) polymorphism are at higher risk of hyperhomocysteinaemia which has been associated with venous thrombosis. However, these associations appear to hold only in countries lacking grain products nutritionally fortified as a public health measure. Moreover, homozygous variants are found in up to 15 per cent of some populations, so that detection of this variant would lead to many women undergoing complex counselling unnecessarily and may also be a cause of distress. Polymorphism is not more prevalent in women with pregnancy-associated venous thromboembolism and testing for this polymorphism is not recommended as part of a routine evaluation for thrombophilia in pregnancy.

Removal of recommendation (2019)

The previous iteration of the SOMANZ ‘Top-Five’ recommendations included:

Do not perform a D-Dimer test for the exclusion of venous thromboembolism during any trimester of pregnancy.

Recent studies have shown that using a D-Dimer in combination with a clinical algorithm can increase the reliability of D-Dimer testing in ruling out DVT and PE in pregnancy.

Furthermore, the alternative to D-Dimer tests for these purposes is the use of imaging tests, which have their own set of risks from radiation exposure. Where previous evidence which suggested D-Dimer testing was highly unreliable would have tipped the scales towards discouraging D-Dimer testing, the new evidence suggests the results of D-Dimer testing can be made more reliable. Thus, it is no longer apparent there would be strong benefits from discouraging the use of D-Dimer testing in these settings if the alternative is imaging.

At a 7 August 2019 meeting of the SOMANZ Council it was agreed this recommendation be removed. The RACP Evolve team and the NPS MedicineWise Choosing Wisely Australia Clinical Lead also undertook a review.

Due to this change in evidence, and physician support, this recommendation was officially removed in August 2019.

Supporting evidence for the removal of this recommendation

Langlois E, Cusson-Dufour C, Moumneh T, et al. Could the YEARS algorithm be used to exclude pulmonary embolism during pregnancy? Data from the CT-PE-pregnancy study. J Thromb Haemost. 2019;17(8):1329-1334
van der Pol LM, Tromeur C, Bistervels IM, et al. Pregnancy-Adapted YEARS Algorithm for Diagnosis of Suspected Pulmonary Embolism. N Engl J Med 2019; 380:1139-1149.*

Original Recommendation: Do not perform a D-Dimer test for the exclusion of venous thromboembolism during any trimester of pregnancy

As D-Dimer levels are raised during pregnancy, they do not have a high positive predictive value for venous thromboembolism (VTE) in pregnancy (i.e. they are unreliable for ruling in VTE in pregnancy). However, nor are they a reliable rule-out test for VTE. One study estimated the sensitivity of the D-Dimer test at 73 per cent, meaning that 27 per cent of patients with a negative D-Dimer had VTE. There have also been case reports of pregnant women with pulmonary embolism presenting with a negative D-Dimer. Therefore, there is no value in performing a D-Dimer test for the exclusion of venous thromboembolism at any trimester in pregnancy.

Supporting evidence

Damodaram M, Kaladindi M, Luckit J, et al. D-dimers as a screening test for venous thromboembolism in pregnancy: is it of any use? Journal of Obstetrics and Gynaecology 2009; 29(2):101-32.
McLintock C, Brighton T, Chunilal S, et al. Recommendations for the diagnosis and treatment of deep venous thrombosis and pulmonary embolism in pregnancy and the postpartum period. Aust N Z J Obstet Gynaecol 2012; 52(1):14-22.
To MS, Hunt BJ, Nelson-Piercy C. A negative D-Dimer does not exclude venous thromboembolism in pregnancy. Journal of Obstetrics and Gynaecology 2008; 28(2):222-40.

Supporting evidence

Den Heijer M, Lewington S, Clarke R. Homocysteine, MTHFR and risk of venous thrombosis: a meta-analysis of published epidemiological studies. J Thromb Haemost 2005; 3:292-9.
Eldibany MM, Caprini JA. Hyperhomocysteinemia and thrombosis: an overview. Arch Pathol Lab Med 2007; 131:872-84.
Holmes MV, Newcombe P, Hubacek JA, et al. Effect modification by population dietary folate on the association between MTHFR genotype, homocysteine, and stroke risk: a meta-analysis of genetic studies and randomised trials. Lancet 2011; 378:584-594.
McLintock C, Brighton T, Chunilal S, et al. Recommendations for the prevention of pregnancy-associated venous thromboembolism. ANZJOG 2012; 52:3-13.

How this list was made

SOMANZ Council members considered potential low value clinical practices in obstetric medicine of relevance to SOMANZ members, and developed a shortlist of nine items. Council members then worked with the RACP to compile and review the published research on each of these practices. Based on the review, the list of potential items of interest was refined down to seven and recommendations for these were formulated.

All Fellows and advanced trainees of SOMANZ were surveyed online for their views on these seven draft recommendations and provided with evidence summaries for each, and for their suggestions of other practices not already included. They were asked to score each recommendation based on whether they thought it was evidence based, currently undertaken in significant volume, and important for reducing harms and/or unnecessary healthcare costs. Based on the scores and feedback, the final top-five recommendations were then finalised and approved by SOMANZ Council.

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