perinatal infection

Question 1

What is the risk of transmission of CMV if primary infection occurs in pregnancy?

Answer 1

30%

Question 2

If CMV is transmitted in pregnancy to the fetus, what is the risk that the fetus/neonate will be affected?

Answer 2

Symptomatic in 10-15%

Asymptomatic in 85-90%

Question 3

If the fetus or neonate are affected by CMV (only 30% transmission, and of those only 10% affected) what is the risk of sequelae?

Answer 3

50% (50% affected with sequelae, 50% affected but with no sequelae)

Question 4

Of the fetus or neonates that are asymptomatic with infection what is the risk of sequelae?

Answer 4

10-15%

Question 5

How do you ascertain whether a woman has primary or secondary CMV?

Answer 5

Testing of IgG and IgM

• if IgG positive and IgM positive avidity testing required (low = recent primary infection, high = old infection)
• if IgG negative and IgM positive then repeat test in 2/52

Question 6

What investigations are possible to review fetal risk if CMV testing indicates primary infection in pregnancy

Answer 6

Fetal USS and fetal MRI - sensitivities of 30-50% and low specificity
Amniocentesis - if performed <20/40 45% sensitive, high specificity, if performed >20/40 80-100% sensitive and high specificity

Question 6

What investigations are possible to review fetal risk if CMV testing indicates primary infection in pregnancy

Answer 6

Fetal USS and fetal MRI - sensitivities of 30-50% and low specificity
Amniocentesis - if performed <20/40 45% sensitive, high specificity, if performed >20/40 80-100% sensitive and high specificity

Question 7

How can you increase sensitivity of amniocentesis for fetal screening?

Answer 7

by waiting >6 weeks following maternal infection

Question 8

what does fetal amniocentesis for CMV actually test?

Answer 8

CMV PCR

Question 9

What would you advise a woman with +ve fetal screening for CMV

Answer 9

Positive result cannot predict the degree of fetal damage

Question 10

What are the 3 main concerns for symptomatic congenital CMV infection?

Answer 10

• early mortality (first 3/12 of life) rates of 5-10%
• neurologica sequelae or microcephaly 35-50%, seizures (10%), chorioretinitis (10-20%), developmental delay (<70%)
• sensory neural hearing loss 25-50%, with progression expected in about half (mainly in the first 2 years of life)

Question 11

What are the 2 main concerns for asymptomatic congenital CMV infection?

Answer 11

• sensorineural hearing loss (5%) with progression in about half with time
• chorioretinitis (2%)

Question 12

What are the steps that need to be taken for a neonate born to a mother with primary CMV?

Answer 12

• thorough physical examination at birth
• serology CMV IgM or CMV PCR from saliva, blood, urine
• If +ve confirms congenital CMV
• categorise into symptomatic and asymptomatic
• if asymptomatic - 3-6 monthly reviews for first 2 years including regular hearing and neurodevelopment testing

Question 13

How can you assess whether a neonate is symptomatic of congenital CMV?

Answer 13

• Head USS - hydrocephalus may be picked up

- brain MRI - intracranial calcifications, ventriculomegaly, cerebral atrophy, white matter abnormalities

Question 14

What is the risk of transmitting HSV in the context of recurrent HSV?

Answer 14

HSV 1 15%
HSV 2 <0.01%
if detected in genital area at time of delivery then overall 1-3% risk
if not then overall risk 1%

Question 15

what is the risk of spontaneous abortion, IUGR and pre term labour with HSV infection?

Answer 15

rare - <1% in either recurrent or new infection

Question 16

what percentage of neonatal HSV infection is accounted for by true intra-uterine infection?

Answer 16

<5%

Question 17

what assessment should you complete for a woman who has had her first suspected episode of HSV in pregnancy or labour?

Answer 17

• type specific PCR +/- genital swab/culture

- HSV type specific serology test

Question 18

How would you interpret HSV 1 + genital swab

with HSV 1 and 2 IgG negative?

Answer 18

primary first episode of HSV infection

• would then have to consider gestation
• if well before 30-34/40 then risk of transmission is same as recurrent HSV

Question 19

if the HSV is in the genital tract, the use of fetal scalp electrodes are contraindicated. What is the OR?

Answer 19

• increased risk of transmission, OR of 6.8

Question 20

what would you advise a woman with current HSV at time of labour regarding mode of delivery?

Answer 20

• caesarean delivery reduces risk of transmission with OR of 0.14

Question 21

what is the risk of transmission if primary HSV infection occurs at time of delivery?

Answer 21

25-50% risk

Question 22

if HSV 1 (or2) +ve and HSV 1 (or 2) IgG +ve what would your management be?

Answer 22

consider suppressive antiviral therapy from 36/40 in women with multiple recurrent overt lesions

Question 23

In someone who has had recurrent HSV in pregnancy and has been on suppressive acyclovir treatment what would you do at time of labour?

Answer 23

inspect for active lesions

• if none, then proceed to vaginal delivery
• consider avoiding FSE, forceps or ventouse, or rather be aware that these may increase risk of transmission

Question 24

what is the dosing of suppressive antiviral treatment?

Answer 24

oral acyclovir 400mg PO TDS | oral valeclovir 500mg PO BD

Question 25

what investigations are required of a baby born in condition high risk for HSV? (Mother with primary HSV at labour or genital lesions identified at labour)

Answer 25

- Lumbar puncture - CSF PCR, HSV PCR, viral culture - blood count for low platelets (HSV attacks erythrocytes) - LFT - HSV PCR on blood - surface swabs - eyes, throat, umbilicus, rectum, urine - Commence IV acyclovir immediately

Question 26

What treatment to babies iwht congenital HSV require?

Answer 26

20mg/kg IV TDS as 1-2 hour infusion

Question 27

what is the treatment for listeriosis in pregnancy?

Answer 27

amoxicillin/ampicillin 2g IV 4-6 hourly for 14 days

Question 28

what is the prognosis for the fetus if listeriosis occurs in the third trimester?

Answer 28

40-50% mortality rate for the fetus

Question 29

how common is listeriosis in Australia?

Answer 29

rare - 0.3 cases per 100,000 of population | but of that 14% are pregnant women

Question 30

how would you detect fetal listeria infection?

Answer 30

- placental, cord or post- pharyngeal granulomas - multiple small skin granuloma - meconium stained/discoloured liquor <34/40 - pneumonitis - purulent conjunctivitis

Question 31

what is the empiric treatment for the unwell neonate when listeria is suspected?

Answer 31

50mg/kg 12 hourly of either amoxicillin or ampicillin

Question 32

what are the two principles used to avoid listeria infection?

Answer 32

- avoid high risk foods | - safe food handling practises

Question 33

which foods are considered high risk for listeriosis infection>

Answer 33

- unpasteurised milk - pates, dips and soft cheeses - chilled, pre cooked seafoods - pre cooked meat - prepared salads

Question 34

if exposed to parvovirus and results are IgG -ve and IgM -ve or IgG -ve IgM +ve what would your next step be?

Answer 34

- either susceptible or recently exposed or false +ve IgM therefore repeat IgG in 2-4 weeks time - if +ve indicates recent infection - if -ve indicates false IgM +ve test

Question 35

What makes listeria more common in pregnancy?

Answer 35

- intracellular infection - reduced cell mediated immunity in pregnancy= more prone (intracellular also means can cross BBB and placenta)