Medium-term storage of frozen residual antenatal sera in gel separator tube is suitable for subsequent serological investigation of intrauterine infection.

Aim: We assessed the feasibility of storing sera in primary gel separator tube over medium-term for retrospective serological tests to facilitate investigation of intra-uterine infection.

Method: 120 residual serum samples, consisting of 30 positive samples each for rubella, cytomegalovirus, parvovirus B19 and varicella zoster IgG were aliquoted into secondary propylene tubes and stored together with the original primary tubes at -20°C for 1 year. The serum was subsequently retested to compare results from both storage methods.

Results: Haemolysis was observed in 49.2% of serum stored in the primary tubes. However, there was no difference in both the qualitative and quantitative results after storage of serum samples in either receptacle.

Conclusion: Sera can be stored in primary blood tube for up to 1 year without affecting serological results. For laboratories with adequate freezer space to store samples in primary blood tubes, this would streamline workflow saving manpower and time, avoid mislabelling of aliquots, reduce consumable costs and prevent unnecessary biohazard exposures.