Abstract
Background
Rh sensitization occurs when women whose red blood cells are Rh(D)-antigen negative develop anti-Rh(D) antibodies either during a previous pregnancy in which the fetus is Rh(D) positive or by exposure to Rh antigens from blood products/transfusion. Neonates born to Rh-sensitized mothers may present with severe jaundice and anemia. Other outcomes may include death from acute or chronic bilirubin encephalopathy, or brain damage resulting from severe neonatal hyperbilirubinemia. Rh disease is now considered rare in countries where Rh prophylaxis is used. In Canada the rate of Rh sensitization and neonatal Rh disease are unknown. Factors that may lead to continued Rh disease in Canada include the immigration of women from countries without universal Rh immunization programs.
Design/Methods
The Canadian Paediatric Surveillance Program was used to send a monthly questionnaire to all pediatricians in Canada to solicit cases of Rh sensitization for two years from May 2016-June 2018. The questionnaire was developed by our group with the case definition being: Any infant 60 days of age or less with Rh(D) sensitization and the Mother is Rh negative (D-negative), the Mother has positive antibody screen due to anti-D (maternal allo-anti-D, not passive anti-D from Rh(D) immunoglobulin), and the cord or infant blood group is Rh positive (D-positive). The complete protocol can be accessed at www.cpsp.cps.ca/surveillance.
Results
Fifty-seven cases of Rh(D) sensitization were reported across Canada between May 2016 and June 2018. The average gestational age of affected was 36.9 weeks (range: 35–40). At presentation, the average age was 6.7 hours, and the average hemoglobin was 135.27g/L (range: 33–200 g/L). The average peak micro bilirubin (MBR) level was 280 µmol/L (range: 67–771 µmol/L), and the average duration of phototherapy was 129 hours. Nearly half of the babies required either pack red blood cell transfusion, IVIG or both. Ten of the affected infants were reported as needing an exchange transfusion. Many of the affected mothers were born outside Canada.
Conclusion
Though rare, Rh disease continues to exist in Canada. Despite current public health measures across the country, additional work must be done to raise awareness of Rh disease, to prevent the disease whenever possible, and to minimize sequelae when it does occur. The ongoing global burden of Rh Disease worldwide, as well as the possibility of emerging Rh immunoglobulin refusal are among factors that should be taken into consideration in future awareness and prevention efforts.