Feto-maternal haemorrhage assessment in a woman with a large population of red blood cells containing fetal haemoglobin

Abstract

Background: FMH quantification is necessary to calculate an individual dose of prophylactic anti-RhD immunoglobulin and to diagnose fetal anaemia causes. We encountered a healthy woman with a numerous RBCs containing fetal haemoglobin (HbF). Aims: To investigate the cause of this sign and the correct evaluation of fetal RBCs in maternal circulation. Materials and Methods: Patient’s samples and artificial mixtures were tested by microscopic Kleihaur-Betke (KB) and flow cytometric (FC) tests with anti-HbF + anti-CA (carbonic anhydrase), and with anti-D. The patient’s blood count with reticulocyte parameters, and concentration of bilirubin, haptoglobin, iron, transferrin, ferritin, hepcidin, sTR, HbF, HbA2 were measured. Genes coding the β- and γ-globin were sequenced. Results: It was impossible to distinguish the population of fetal and maternal HbF positive cells using KBT and FC with anti-HbF. Application of anti-CA and anti-D allowed to separate them. Maternal blood haematological and biochemical parameters were normal but HbF was 3.3% of total Hb concentration (normal <1%). There were no mutations in the β- and γ-globin genes, but Xmn I polymorphism at –158 position in γ-globin gene was detected in the homozygous state. Conclusion: A very large population of HbF positive cells sometimes can be detect in a healthy woman. Implementation of the various procedures for FMH assessment is necessary in the such case, otherwise, the detection of fetal erythrocytes may not be possible or can give false results.