Pregnancy: exposure (chickenpox, measles, parvovirus B19, CMV) or serology to interpret (toxoplasmosis, rubella, CMV)

Urgent (result useful within 10 days of the contact)

• Varicella serology (IgG, immune status), urgent
• IgG negative: maternity unit opinion the same day for specific anti-VZV immunoglobulins.

Urgent (result useful within 6 days of the contact)

• Measles serology (IgG), urgent, only if status is doubtful
• Not immune (no certain history and not two vaccine doses): polyvalent IV immunoglobulins within 6 days, in hospital, in liaison with the reference maternity unit.

Laboratory tests

• Parvovirus B19 IgG and IgM serology (diagnosis of recent infection)
• Repeat IgG and IgM serology (if negative before the end of the incubation period)if needednon-French guidelineNegative IgG and IgM: the woman is neither immune nor infected only if the incubation period has passed; otherwise, a repeat test is to be planned ^[16].

Laboratory tests (state on the prescription: current pregnancy and date of start of pregnancy)

• CMV IgG and IgM serology
• Anti-CMV IgG avidity (on the same serum, if IgG and IgM positive)if neededPositive IgG and IgM: avidity dates the infection; an intermediate avidity is rechecked with another kit or in an expert laboratory ^[2,19]. The laboratory performs it straight away on the same sample, without a new prescription ^[20].

5 to 10 days later (IgM positive or equivocal, IgG negative)

• Repeat CMV IgG and IgM serology (new sample)if neededPositive or equivocal IgM with negative or equivocal IgG (possible start of primary infection): repeat on a new sample 5 to 10 days later; the laboratory also looks for CMV genome in the blood ^[20,21].

3 weeks later (exposure in a non-immune woman, IgG negative)

• Repeat CMV IgG and IgM serologyif neededContact in a pregnant woman known to be non-immune: serology as soon as possible, repeated 3 weeks later if IgG are negative ^[21].

On valaciclovir 8 g/day: at day 7, then every 15 days

• Serum creatinine with GFRif neededPericonceptional or 1st-trimester primary infection treated with valaciclovir 8 g/day: monitoring of renal function in the first week, then every 15 days ^[20].

In the same laboratory, sending the previous serum

• Confirmation of IgM by another technique (new sample)
• Anti-Toxoplasma IgG avidity (on the initial serum, if IgG present and IgM confirmed)if neededIgG present and IgM confirmed by a second technique: avidity, done on the initial serum, dates the infection ^[2].

2 to 3 weeks after the first sample

• Second sample: IgG kinetics, titrated in the same run and with the same technique as the first

On pyrimethamine-sulfonamide (treatment prescribed by the reference centre): every 1 to 2 weeks

• FBCif needednon-French guidelineTreatment with pyrimethamine and a sulphonamide (proven fetal infection or maternal infection in the 3rd trimester): FBC every 1 to 2 weeks; neutrophils < 1 500/mm³: stop treatment, continue folinic acid and repeat FBC one week later ^[26].

Laboratory tests

• Rubella serology
• Rubella IgM (suspected exposure or infectious syndrome of less than 4 to 5 weeks)if neededSuspected exposure or infectious syndrome dating from less than 4 to 5 weeks: the fee schedule reserves IgM testing for this context ^[2].