There is emerging data suggesting that genetic testing of pregnancy tissue may have some prognostic value.

Introduction

Fetal genetic abnormalities are a recognised cause for both sporadic and recurrent pregnancy loss (RPL). The prevalence of genetic abnormalities is estimated to be 45% for a single pregnancy loss and 39% where a pregnancy loss is preceded by RPL history.1

There is emerging data suggesting that genetic testing of pregnancy tissue may have some prognostic value. However, in the absence of any high-quality evidence to demonstrate this, the current international consensus is not to offer routine genetic testing of pregnancy tissue for every pregnancy loss.2

The primary reason for determining the genetic status of pregnancy tissue is to identify a possible cause, thus potentially offering women and their partners some closure.

Bullet point guidance

  • Genetic analysis of pregnancy tissue is not routinely recommended. However, the pregnancy tissue should be tested after the third pregnancy loss in a dry specimen pot if possible (i.e., without formalin). The recommended test is array-based comparative genomic hybridization (array-CGH).2
  • Genetic analysis of pregnancy tissue is performed for explanatory purposes.
  • Where an unbalanced translocation is identified in the pregnancy tissue, parental karyotyping should be organised. People with abnormal karyotypes should be offered a referral to clinical genetics.2
  • Women with a history of recurrent pregnancy loss should be provided with a dry histology pot so that if a miscarriage occurs or medical management of miscarriage is performed, pregnancy tissue can be collected and sent for cytogenetic analysis at the local early pregnancy assessment unit.
  • For women who choose to have surgical management of miscarriage, the theatre team should be instructed to collect the pregnancy tissue in a dry histology pot to be sent for cytogenetic analysis.
  • Women should be counselled that in some circumstances cytogenetic analysis cannot be performed on the pregnancy tissue that is sent due to contamination with maternal tissue or lack of fetal tissue.
  • It is advisable for recurrent miscarriage clinic staff members to be aware of local policies regarding where cytogenetics and histology samples should be sent and stored out of normal working hours.
  • A robust system should be in place for debriefing couples and discussing the results of their cytogenetic analysis.

References

  1. van den Berg MMJ, van Maarle MC, van Wely M, Goddijn M. Genetics of early miscarriage. Biochimica et Biophysica Acta – Molecular Basis of Disease. 2012.
  2. ESHRE Early Pregnancy Gudeline Development Group. Recurrent Pregnancy Loss. European Society of Human Reproduction and Embryology (ESHRE). 2017. 1–154 p.