Infections In Pregnancy including Chicken Pox GT13 Flashcards
What percentage of pregnancies are complicated by VZV?
3 in 1000
What percentage of pregnant women infected with VZV develop varicella pneumonia?
10-20%
what percentage of people over 15yrs, in the UK, are positive for VZV IgG?
> 90%
after being vaccinated against varicella zoster, for how long should a woman avoid pregnancy. What should she do if she develops a post- vaccination rash?
1 month, after completing the 2 dose vaccine.
She should avoid pregnant women if she has a post-vaccination rash
if a woman has been exposed to chicken pox and then received VZIG, from what time period is she considered potentially infectious?
What if she did not receive VZIG, from when is she considered infectious?
from 8-28 days after exposure
if no VZIG; from 8-21 days after exposure
what is the definition of “significant contact” with chicken pox?
contact in the same room for 15 minutes or more, face-to-face contact or contact in the setting of a large open ward
for how long is chicken pox infectious?
Chickenpox is infectious for 2 days before the appearance of the rash and for the duration of
the illness while the skin lesions are active. It ceases to be infectious when the lesions have crusted over.
what are the main maternal risks of chicken pox in pregnancy?
pneumonia, hepatitis, encephalitis.
What is the mortality rate from varicella pneumonia?
Mortality from varicella pneumonia is 0-14%
when should oral acyclovir be given to women who develop chicken pox? after what gestation is considered safe?
What is the dose and duration?
PO acyclovir 800mg 5 times a day for 7 days for women who present within 24 hours of onset of rash. After 20/40 gestation
What symptoms may be considered as ‘severe’ chicken pox, warranting hospital assessment?
Respiratory symptoms,
photophobia, seizures or drowsiness,
haemorrhagic rash or bleeding, or a dense rash with or without mucosal lesions
What is the minimum ideal time between onset of chicken pox rash, and delivery
7 days
If sooner - also risk of haemorrhage/coagulopathy (thrombocytopenia/hepatitis)
which type of regional anaesthesia is considered safe in chicken pox, when delivering by caesarean section.
epidural- as the dura mater is not penetrated, however, larger bore of needle may transfer more virus to epidural space. Choose needle site free of lesions
True or false-
If chicken pox occurs in the first trimester, risk of spontaneous miscarriage is increased
FALSE. risk of miscarriage doesnt appear to be increased
What are the 4 main characteristics of Fetal Varicella Syndrome
- skin scarring in a dermatomal distribution;
- eye defects (microphthalmia, chorioretinitis or cataracts);
- hypoplasia of the limbs
- neurological abnormalities (microcephaly, cortical atrophy, mental retardation or dysfunction of bowel and bladder sphincters)
Does fetal varicella syndrome occur at the time of initial fetal infection?
No.
It results from a subsequent herpes zoster reactivation in utero.
Only occurs in a minority of infected fetuses.
If a woman develops chicken pox in pregnancy, when should she be referred to fetal medicine?
at 16-20 weeks, or 5 weeks after infection- for discussion and detailed USS
Does amniocentesis have a poor positive predictive value for detecting fetal damage from chicken pox?
Yes. poor positive predictive value, strong negative predictive value.
does VZV DNA detected in amniotic fluid have a high or low sensitivity for development of fetal varicella syndrome?
VZV DNA presnet in amniotic fluid has HIGH sensitivity and LOW specificit for development of FVS (Fetal varicella syndrome)
what percentage of babies are infected with chicken pox if the mother develops chicken pox 1-4 weeks before delivery?
50%
what percentage of babies exhibit clinical varicella if the mother develops chicken pox 1-4 weeks before delivery?
23%
What treatment is given to neonate if mother develops chickenpox within the period 7 days before to 7 days after delivery
VZV immunoglobulin +/- IV acyclovir
can women breastfeed with chicken pox?
yes. If they are well enough to do so. If there are lesions close to nipple, can express breast milk
If a varicella susceptible woman has been exposed to chicken pox, in what time frame should she receive VZIg
within 10 days
What happens if a woman has been exposed a second time to chicken pox, after previously having had VZIg for exposure to chicken pox 5 weeks ago?
She will need a further dose of VZIG as 3 weeks have elapsed since the last dose
What is the risk of transmission of herpes if woman presents with first episode in third trimester- 6 weeks before delivery
41%
In women with recurrent genital herpes, what is the risk of transmission to fetus
0-3%
In women with HIV and history of genital herpes, from what gestation should acyclovir suppression be given?
From 32 weeks
400mg TDS
What type of virus is varicella zoster?
Human herpesvirus 3
Double stranded DNA
What is the incubation period of VZV?
1-3 weeks
What is the advice re: breastfeeding and pregnancy following Varivax/Varilrix immunisation and what is the schedule?
2 x 4-8 weeks apart
Live attenuated virus
Safe to breastfeed
Avoid pregnancy 4/52 after vaccination and contact with pregnant women if rash occurs
When should VZIG be given if non-immune with significant contact with chickenpox?
And when may 2nd dose required?
Within 10/7 of the index case in the houshold
2nd dose if further exposure >3/52 since last
When should women with chickenpox be referred to hospital?
- Respiratory symptoms; if severe/deteriorating
- Neuro - photophobia, seizures etc
- Dense rash +/- mucosal lesions
- If uncomplicated but - smoker, chronic lung disease, immunsuppressed (incl. steroids for 3/12) or 2nd half of pregnancy
When is a woman at greatest risk at fetal varicella syndrome?
First 28/40
When should women be referred to FMU after exposure to VZV?
18-20 weeks or 5/52 post infection
What is the risk of intrauterine infection (by gestational age) of Rubella?
<11/40 - 90%
11-16/40 - 55%
>16/40 - 45%
What is the risk of intrauterine infection (by gestational age) of parvovirus B19?
<4/40 - 0%
5-16/40 - 15%
>16/40 - 25-70% (increases with gestational age)
What is the risk of intrauterine infection (by gestational age) of Varicella?
<28/40 - 5-10%
28-36/40 - 25%
>36/40 - 50%
What is the risk of adverse fetal outcome with Rubella?
<11/40 - 90% - offer TOP
11-16/40 - 20%
16-20/40 - Minimal risk of deafness
>20/40 no increase risk
What is the risk of adverse fetal outcome with Parvovirus b19?
<20/40 - 9% excess fetal loss (15 vs 9%)
9-20/40 3% hydrops of which 50% will die
What is the risk of congenital varicella syndrome/neonatal chickenpox with Varicella?
<13/40 - 0.4%
13-20/40 - 2%
Neonatal chickenpox risk from 4/7 before to 2/7 after delivery - 20%
What is the incubation period for rubella and when is one infective?
14-21 days
Infective 7/7 pre to 10/7 post rash
What is the incubation period for Parvovirus B19 and when is one infective?
14-21 days
Infective 10/7 pre rash to the day it devlops
What is the incubation period for Varicella and when is one infective?
10-21 days
2/7 pre-rash until lesions crusted - longer if VZIV given
What kind of virus is Rubella?
single stranded RNA
Togaviridae
What kind of virus is Parvovirus B19?
Single stranded DNA
What kind of virus is CMV?
Double stranded DNA herpes family
What is the birth prevalence of congenital CMV?
3/1000
What type of virus is HHV6-7?
Double stranded DNA
May cause roseola infantum
1% population contain the DNA in their genome
No long term consequences
What are the characteristics of fetal varicella syndrome?
Low birthweigh
Multisystem issues - neuro, eye, skeletal abnormalities, skin scarring, limb hypoplasia
What is the risk of vertical transmission of CMV?
40% in T1 and T2
Fetal damage in 10%; further 10-25% will devlop sequlae later, usu deafness
80% T3 but asymptomatic after 27/40
What are the features of congenital CMV?
Ocular defects incl cataracts Sensorineural deafness hepatosplenomegaly jaundice thrombocytonic purpura pneumonitis FGR Microcephaly LD and epilepsy
