Infection in pregnancy - GBS, HIV, syphilis, HCV, HBV, HSV, PVB19, Listeria, Malaria Flashcards
What infections are screened for antenatally?
- HIV - if declined at 8-12 weeks then offer again at 28 weeks
- Syphilis
- Hepatitis B
What are the complications of syphilis antenatally and postnatally?
If untreated 70-100% of infants will be infected and 25% stillborn; can also cause FGT, fetal hydrops, congenital syphilis (with long term disability), perterm birth.
Postnatally it can cause active disease in newborn infants if contracted and can cause neonatal death
Does risk of congenital syphilis increase with increasing duration of maternal syphilis prior to pregnancy?
No - the risk of congenital transmission declines with increasing duration of maternal syphilis prior to pregnancy.
What are the clinical features of syphilis?
Primary syphilis = painless genital ulcer at 3-6 weeks after infection (condylomata lata) BUT may be on the cervix and go unnoticed
Secondary syphilis = 6weeks to 6 months after infection
- Maculopapular rash
- Lesions affecting mucous membranes
Tertiary syphilis =
- 20% develop cardiovascular problems
- 5-10% develop symptomatic neurosyphilis
What is the trend in syphilis infections in the UK?
Incidence is low and falling in women but increasing infection rates in men (may be due to MSM)
About 0.15% of pregnancies screened will be positive for syphilis
How do you test for syphilis in pregnancy?
Screening -
Non-treponemal tests detect non-specific treponemal antibodies = VDRL + RPR (some false negatives)
Treponemal tests detect specific treponemal antibodies = EIAs + TPHA + FTA-abs
- Venereal Diseases Research Laboratory = VDRL
- rapid plasma reagin = RPR
- enzyme immunoassays = EIAs - detects IgG and IgM and are replacing the VDRL ad TPHA tests for screening in the UK as they are 98% sensitive and 99% specific
- T. pallidum haemagglutination assay = TPHA
- fluorescent treponemal antibody-absorbed test = FTA-abs
What increases the false negative rates in syphilis screening using non-treponemal tests?
Increased chance of false negatives with:
- Very early of late syphilis
- Reinfection
- HIV-positive
Increased chance of false positive with:
- Lupus
- Therefore refer to specialist for definitive diagnosis.*
What is the management of syphilis in pregnancy?
- Refer to GUM for appropriate contact tracing
- Antibiotics - 1.8g IM stat benzylpenicillin (1st line). More than 1 injection may be required.
What should also be done if the syphilis is not treated during pregnancy?
Treat baby immediately after delivery with IM benzylpenicillin - otherwise serious complications including developmental delay, seizures or death may occur within a few weeks
What is a complication of treatment of syphilis?
Jarish–Herxheimer reaction
Occurs due to release of proinflammatory cytokines in response to dying organisms –> worsening of symptoms, and fever for 12–24 hours
Mayy be associated with uterine contractions and fetal distress so ?admit at time of treatment commencement
How do you treat syphilis in pregnancy if the woman is penicillin allergic?
There is little evidence for use of non-penillin regimens. So offer penicillin desensitisation and post-desensitisation IM benzylpenicillin
When is HIV transmission from mother to child most likely to occur?
3rd trimester, labour, delivery or breast feeding
How long can the period between HIV infection and development of AIDS range from?
Few months to 17 years in untreated patients
How common is HIV in pregnant women? What is the risk of transmission to infant if the HIV is treated?
2 per 1000 affected
0.1% risk of transmission with treatment
What are the risk factors for vertical transmission of HIV?
What interventions are used to minimise vertical transmission of HIV in pregnancy?
- Initiation of ART by 24 weeks’ if ART-naive
- Planned elective C-section if viral load >400 HIV RNA copies/ml at 36 weeks’
- Exclusive formula feeding from birth regardless of viral load and ART use
Can women with HIV still have a planned vaginal delivery?
Yes - it is an option if viral load is <50 copies/ml at 36 weeks’ gestation
Otherwise C/S if >50 copies/ml, or if taking zidovudine(ZDV)/ monotherapy.
What is the antenatal management of HIV in pregnancy?
- Refer to joint HIV physician and obstetric clinic every 1-2 weeks at 35 weeks and delivery
- Monitor HIV viral load every 2-4 weeks at 36 weeks and delivery
- Monitor CD4 count at baseline and delivery
- ART - offer regardless of whether taken previously
What is the intrapartum management of HIV?
Mode of delivery depends on viral load at 36 weeks gestation:
- < 50 copies/mL → reassure that vaginal delivery is appropriate
- >50 copies/mL or co-existent hepatitis C → recommend elective C-section with intrapartum IV zidovudine at 38 weeks.
- If >1000 copies/ml at delivery - give IV AZT.
Cord should be clamped ASAP and the baby should be bathed immediately after birth
What is the postnatal management of HIV in pregnancy?
- Do not breastfeed - only applicable for women in UK; in under-resourced countries it is best for the infant to breastfeed
-
ART for infant within 4 hours of birth
- If low-risk → zidovudine monotherapy for 2-4 weeks
- If high-risk → triple ART (zidovudine, lamivudine and nevirapine) for 4 weeks
- NAAT/PCR for neonate on discharge then at 3 weeks, 6 weeks and 6 months - this is because Ab test cannot be used as maternal HIV antibodies will be present
What types of viruses are hep B and C?
HBV - DNA virus
HCV - RNA virus
Without Hep B treatment in pregnancy, what % of babies will contract Hep B? What about in Hep C
HBV = 90% will develop chronic infection
HCV = 3-5% transmission
What is chronic Hep B infection associated with?
- Liver failure
- Cirrhosis
- HCC
What is the management of an infant born to a Hep B positive mother?
At <12 hours of life;
- Hep B vaccination - at birth
- Hep B immunoglobulin - dose within 12 hours of life; confers 95% protection against chronic Hep B infection
What is the current immuniation schedule for infants born to HBsAg positive mothers?
- at birth (dose 1)
- 1 month following dose 1
- 2 months following dose 1
- 12 months following dose 1, + blood test for serology to check infection and immunity status.
What does the Hep B screening test look at in pregnancy?
- HBsAb - implies immunity to hepatitis B
- HBsAg - indicates presence of hepatitis B
- HBcAb - indicates previous exposure to hepatitis B
NB: detection of HCV involves anti-HCV antibodies in the serum but this is not routinely screened for.
What is the management of hepatitis B in pregnancy?
Antenatally -
- Refer to hepatologist
- Offer tenofovir if HBV is high (HBV DNA >107 IU/ml) - start in 3rd trimester and stop 4-12 weeks after delivery unlessotherwise indicated.
- Monitor HBV viral load every 2 months and LFTs monthly
Postnatally -
- Offer hepatitis B Ig and hep B immunisation to newborn
- Serology at 12 months to test infant for Hepatitis B following immunistations
- Ecourage breastfeeding
What is the risk of transmission of hepatitis B to an infant during breastfeeding?
0 - no risk of transmission with breastfeeding
How can you tell if a patient is highly infectious with HBV?
HBeAg positivity
Screening for Hep C is only offered to women who are considered to be high risk. What does high risk include?
- Current or previous IV drug use
- Hepatitis B
- HIV
What is the risk of transmission of hepatitis C in pregnancy?
- 5% for vertical transmission
- 36% if also coninfected with HIV
What does screening for hepatitis C include?
HCV IgG antibodies
What is the management of HCV in pregnancy?
Antenatally
- Refer to hepatologist - NB normal treatments like ribavirin and interferon are contraindicated in pregnancy
Inrapartum
- No specific precautions
Postnatally
- Start treatments for HCV
What is the most common cause of severe early-onset infection in newborns? What is the mortality associated with this?
GBS is the most common cause of this at <7 days age
Mortality from early onset GBS disease in the UK is 6% in term infants and 18% in preterm infants.
How common is GBS carriage in the vagina? Is it screened for?
~21% of women carry it in the vagina as a commensal
Not routinely screened for in pregnancy
What are the signs/symptoms of GBS in pregnancy?
Mother - asymptomatic as this is a common commensal
Infant - neonatal sepsis with sudden collapse, tachypnoea, nasal flaring, poor tone, jaundice –> treat promptly with broad-spectrum antibiotics
What risk factors/indications for GBS prophylaxis intrapartum?
- Intrapartum fever (>38°C)
- Prolonged rupture of membranes >18 hours
- Prematurity <37 weeks
- Previous infant with GBS*
- Incidental detection of GBS in current pregnancy
- GBS bacteruria*
*strong risk factors
What is the antenatal management of GBS?
If detected incidentally, GBS treatment is still NOT recommended as it does not reduce likelihood of GBS colonisation at time of delivery.
What is the intrapartum management of GBS?
In vaginal delivery:
-
Non-penicillin allergic:
- Benzylpenicillin 3g IV as soon as possible after onset of labour; then 1.5g 4-hourly until delivery.
-
If penicillin allergic:
- Clindamycin 900mg IV 8-hourly
In caesarean section:
- No need for GBS prophylaxis
How good are IV antibiotics at preventing neonatal GBS infection intrapartum?
60-80% effective
What should you do if there are signs of chorioamnionitis in GBS positive pregnant woman intrapartum?
If there are signs of chorioamnionitis then use broad-spectrum antibiotics instead of GBS prophylaxis.
What is the management of suspected neonatal GBS infection ?
Investigations:
- Blood cultures
- Consider CSF cultures
Treatment:
- Broad spectrum antibiotics - IV penicillin + gentamicin
What is the most common ulcerative sexually-transmitted infection in the UK? How common is neonatal HSV?
Herpes simplex virus
Affects 5 per 100,000 births
What type of virus is HSV?
Double stranded DNA virus
Two types are HSV1 and HSV2
What are the three types of neonatal herpes? How is it acquired?
Neonatal herpes has high morbidity and mortality.
- It is most commonly acquired at or near the time of delivery by direct contact with infected maternal secretions.
- Rarely congenital herpes can occur as a result of transplacental uterine infection
How does genital herpes present?
Ulcerative lesions on the vulva, vagina or cervix
In primary infection there may be systemic symptoms
What are the risk factors for transmission of HSV from mother to neonate?
- Primary genital herpes acquired in third trimester* (esp within 6 weeks of delivery as baby will be born before development of protective antibodies and viral shedding may persist)
- Absence of transplacental maternal neutralising antibodies
- Long duration of rupture of membranes before delivery
- Use of fetal scalp electrodes
- Vaginal delivery
What test is used to confirm maternal HSV infection?
Viral swab - direct detection of HSV
What is the antenatal management of maternal herpes simplex infection?
Refer to GUM - to confirm diagnosis and screen for others
Aciclovir 400mg TDS - reduces duration and severity of symptoms and decreases duration of viral shedding. Well tolerated and safe in pregnancy
How can you confirm is the HSV episode was a primary or recurrent infection?
Type-specific HSV antibody presence will indicate recurrent infection i.e. if the same type as that on vaginal swab
NB: this is only tested for if the due date is within 6 weeks
What is the management of primary HSV infection in pregnancy…?
- in 1st or 2nd trimester
If infection occurred in the 1st or 2nd trimester:
- Treat HSV infection with oral aciclovir (400mg TDS for 5 days)
- Recommend daily suppressive oral aciclovir from 36 weeks gestation until delivery
- Offer vaginal delivery
What is the management of primary HSV infection in pregnancy…?
- in 3rd trimester
If 3rd trimester/ <6 weeks until delivery:
- Elective C-section recommended - especially for those with symptoms within 6 weeks of delivery date. SVD has a transmission rate of 41%.
- Oral acyclovir 400mg TDS until delivery
-
If woman still opts for vaginal delivery…
- Avoid rupture of membranes
- Avoid invasive procedures like fetal scalp electrodes
- IV aciclovir intrapartum
- IV aciclovir to nenonate after birth
What is the management of recurrent HSV in pregnancy?
Recurrent episode of genital herpes during antenatal period is NOT an indication for delivery by C-section as risk of neonatal herpes is much lower (1-3%)
If _>_36 weeks with recurrent HSV:
- Aciclovir 400mg TDS until delivery
- Offer vaginal delivery
- Expedited delivery
- Avoid invasive procedures during labour
How is Parvovirus B19 transmitted? How widespread is immunity to PVB19? Why is there no screening?
- Respiratory droplet transmission
- 50% of women of childbearing age have immunity
- No screening as there is no routine agreed treatment or prevention method to protect the baby from infection
What are the clinical features of PVB19 infection?
- Asymptomatic (~20%) or mild flu-like illness +/- arthropathy
- Slapped cheek syndrome in children
- Aplastic anaemia in fetus
- Hydropic fetus - due to high output cardiac failure and livver congesion
When is the fetus most vulnerable to transplacental infection by parvovirus B19?
Second trimester.
This can cause aplastic anaemia but in most fetuses there will be spontaenous resolution with no long-term consequences.
How do you detect anaemia in a fetus e.g. aplastic anaemia in PVB19 infection?
High velocity of blood flow in the middle cerebral artery measured by Doppler ultrasound.
How is maternal PVB19 infection diagnosed?
- Seroconversion - previously seronegative mother now has IgM antibodies to PVB19
- Viral DNA amplification/PCR - fetal and maternal serum or amniotic fluid are the most sensitive and accurate for diagnosis
What is the management of uncomplicated PVB19 infection?
Mother - conservative management
Fetus -
- Refer to fetal medicine specialist within 4 weeks of onset of symptoms for regular surveillance
What is the management of complicated PVB19 infection in the fetus?
If fetal anaemia or hydrops foetalis then…
- Expectant management - 50% will resolve with no long-term sequelae
OR
- In utero transfusion - allways offer if infection occurs in the first 20 weeks of pregnancy (because loss of fetus is high ~10%) NB: fetal transfusion is not possible at early gestations.
What is the prognosis with PVB19 infection for the fetus?
- No neurological damage
- If <20 weeks then 10% mortality
- If >20 weeks then 1% mortality
- If anaemia is treated with in utero transfusions then fetus will make a complete recovery
How does risk of Listeria monocytogenes differ in the pregnant vs non-pregnant population?
Pregnant women are at x18 risk - probably due to reduced cell-mediated immunity as occurs in pregnancy
What is the source of Listeria infections?
Contaminated food (does not multiply in freezer and not transmitted in hot foods but does multiply at refrigerator temps)
- unpasteurised milk
- ripened soft cheeses
- pate
So avoidance is by dietary modification.
What are the clinical features of Listeria in pregnancy?
- Flu-like illness
- Fever
- General malaise
- Asymptomatic in 1/3
How is Listeria transmitted to the fetus?
- Ascending route through the cervix
- Transplacentally secondary to maternal bacteraemia
What % of pregnancies affected by Listeria end in miscarriage or stillbirth?
20%
and 50% may result in premature delivery
What are the clinical features of neonatal Listeria infection?
- Respiratory distress
- Fever
- Sepsis
- Neurological symptoms
mortality 38%
How is listeriosis diagnosed?
Clinical suspicion e.g. meconium staining or amniotic fluid in preterm fetus may increase clinical suspcion for listeriosis
Isolation of organism from blood, vaginal swab or placenta
What is the management of Listeria in pregnancy
Antibiotics - IV amoxicillin 2g 6-hourly for 2 weeks
+Prevention - avoid high risk foods
What are the 5 species of malaria? Whis is of the greatest importance and has the worst prognosis for mother and fetus?
- Plasmodium falciparum - worst prognosis for mother and fetus
- P vivax
- P ovale
- P malariae
- P knowlesi
Why might diagnosis of malaria in pregnancy be missed on blood film?
Malarial parasites are often found in large numbers sequestrated in the placenta even when blood films are negative
High index of suspicion is required with careful examination of the placenta
What are the clinical features of malaria in the mother ?
- Cyclical spiking pyrexia (may cause miscarriage or preterm labour)
- Severe anaemia which can develop quickly
- Hypoglycaemia
- Pulmonary oedema due to abnormal capillary permeability (causes high mortality of ~50%)
- Jaundice and renal failure due to haemolysis
What are the clinical features of malaria in the fetus?
- Premature delivery
- FGR
- Placental sequestration of parasites
- Abnormal uteroplacental Doppler waveforms
NB: Higher rates of transmission of HIV - coinfection with HIV is common in many areas where malaria is endemic and vertical transmission of both together is more common
What is the management of malaria in pregnancy?
Refer to specialist - expert advice needed for which antimalarial is appropriate for the area; some risks of teratogenicity
Antimalarial treatment - depends on local patterns of disease and resistance
Prevention in endemic areas -
- Insecticide-treated nets and intermittent preventative treatment during pregnancy;
- Avoid travel to endemic areas unless absolutely necessary during pregnancy
