Consider referring a patient with Parvovirus B19 infection for specialist evaluation if they are pregnant, particularly in the first or second trimester, due to the risk of fetal complications such as hydrops fetalis and miscarriage. Specialist referral is also warranted if the patient develops severe or persistent anemia, aplastic crisis (especially in those with underlying hemolytic disorders), or if there is evidence of myocarditis or other severe systemic involvement.
In pregnancy, early specialist input is crucial for monitoring fetal well-being with ultrasound and possible intrauterine interventions, as Parvovirus B19 can cross the placenta and infect the fetus, leading to serious outcomes Crane et al. 2014 NICE NG12.
Outside pregnancy, referral should be considered if the diagnosis is uncertain, if there are atypical or severe manifestations, or if immunocompromised patients fail to clear the infection, as they may require specialist management including intravenous immunoglobulin therapy Crane et al. 2014 NICE NG12.