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Obstetrics > perinatal infection > Flashcards

perinatal infection Flashcards

1
Q

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

A

30%

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2
Q

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

A

Symptomatic in 10-15%

Asymptomatic in 85-90%

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3
Q

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

A

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

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4
Q

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

A

10-15%

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5
Q

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

A

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
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6
Q

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

A

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

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6
Q

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

A

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

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7
Q

How can you increase sensitivity of amniocentesis for fetal screening?

A

by waiting >6 weeks following maternal infection

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8
Q

what does fetal amniocentesis for CMV actually test?

A

CMV PCR

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9
Q

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

A

Positive result cannot predict the degree of fetal damage

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10
Q

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

A
  • 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)
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11
Q

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

A
  • sensorineural hearing loss (5%) with progression in about half with time
  • chorioretinitis (2%)
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12
Q

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

A
  • 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
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13
Q

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

A
  • Head USS - hydrocephalus may be picked up

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

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14
Q

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

A

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%

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15
Q

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

A

rare - <1% in either recurrent or new infection

16
Q

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

A

<5%

17
Q

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

A
  • type specific PCR +/- genital swab/culture

- HSV type specific serology test

18
Q

How would you interpret HSV 1 + genital swab

with HSV 1 and 2 IgG negative?

A

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
19
Q

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

A
  • increased risk of transmission, OR of 6.8
20
Q

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

A
  • caesarean delivery reduces risk of transmission with OR of 0.14
21
Q

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

A

25-50% risk

22
Q

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

A

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

23
Q

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

A

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
24
Q

what is the dosing of suppressive antiviral treatment?

A

oral acyclovir 400mg PO TDS

oral valeclovir 500mg PO BD

25
Q

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)

A
  • 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
26
Q

What treatment to babies iwht congenital HSV require?

A

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

27
Q

what is the treatment for listeriosis in pregnancy?

A

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

28
Q

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

A

40-50% mortality rate for the fetus

29
Q

how common is listeriosis in Australia?

A

rare - 0.3 cases per 100,000 of population

but of that 14% are pregnant women

30
Q

how would you detect fetal listeria infection?

A
  • placental, cord or post- pharyngeal granulomas
  • multiple small skin granuloma
  • meconium stained/discoloured liquor <34/40
  • pneumonitis
  • purulent conjunctivitis
31
Q

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

A

50mg/kg 12 hourly of either amoxicillin or ampicillin

32
Q

what are the two principles used to avoid listeria infection?

A
  • avoid high risk foods

- safe food handling practises

33
Q

which foods are considered high risk for listeriosis infection>

A
  • unpasteurised milk
  • pates, dips and soft cheeses
  • chilled, pre cooked seafoods
  • pre cooked meat
  • prepared salads
34
Q

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

A
  • 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
35
Q

What makes listeria more common in pregnancy?

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

Obstetrics (28 decks)

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