Obstetrics Pt.3 Flashcards
How is Rubella spread?
Why is its perinatal infection uncommon?
- Togavirus spread by droplet transmission
- Very uncommon in the UK thanks to MMR
Describe Rubella screening
- Prevalence of rubella has reached such low levels in the UK that screening is NO LONGER ROUTINELY OFFERED
- For women who are screened and rubella antibody is NOT detected, they should be offered the MMR after pregnancy
- NOTE: the vaccine itself is contraindicated in pregnancy because it is a live vaccine
What are the clinical features of Congenital Rubella Syndrome?
- Sensorineural deafness
- Congenital cataracts
- Blindness
- Encephalitis
- Endocrine problems
What is the risk of CRS?
- The risk of CRS decreases with gestation and the manifestations are less severe
- Rubella infection before 11 weeks has 100% risk of CRS
- Rubella infection > 20 weeks has no risk of CRS
What is the management of CRS?
- If infection during pregnancy is confirmed, risk of CRS should be assessed
- If it has occurred < 16 weeks, termination of pregnancy should be offered
What is Syphilis and its clinical features?
- Caused by Treponema pallidum
Clinical Features
- Painless genital ulcer 3-6 weeks after infection is acquired (condylomata lata)
- NOTE: this may be on the cervix and hence go unnoticed
- Secondary manifestations occur 6 weeks to 6 months after infection with a maculopapular rash or lesions affecting the mucous membranes
- If untreated, some will develop symptomatic cardiovascular tertiary syphilis and some will develop neurosyphilis
- In pregnant women with early, untreated syphilis, most infants will be infected and 25% will be stillborn
What are the risks of syphilis in pregnancy?
- FGR
- Foetal hydrops
- Congenital syphilis (may cause long-term disability)
- Stillbirth
- Preterm birth
- Neonatal death
- IMPORTANT: adequate treatment with benzathine penicillin markedly improved the outcome for the foetus
Describe Syphilis Screening in pregnancy
- Routine antenatal screening is offered for ALL pregnant women
- Treponemal antibodies are detected in serology
- Non-treponemal tests detect non-specific treponemal antibodies
- Venereal disease research laboratory (VDRL) test
- Rapid plasma reagin test (RPR)
- NOTE: they have a high false-positive rate
- Treponemal tests detect specific treponemal
- EIAs
- Very sensitive and specific
- Treponema pallidum haemagglutination assay (TPHA)
- Fluorescent treponemal antibody-absorbed test (FTA-abs)
- EIAs
- IMPORTANT: none of these tests will detect syphilis in the incubation stage
What is the management of syphilis in pregnancy?
- Confirm the diagnosis and test for other STIs
- GUM clinic should initiate appropriate contact tracing
- Parenteral penicillin (benzathine penicillin) has a 98% success rate at preventing congenital syphilis
- A Jarish-Herxheimer reaction may occur with treatment as a result of the release of proinflammatory cytokines in response to dying organisms
- Causes worsening of symptoms and fever for 12-24 hours after starting treatment
- May be associated with uterine contractions and foetal distress
- So, women may be admitted during treatment for monitoring
- If the woman is NOT treated during pregnancy, the baby should be treated after delivery immediately
What is Toxoplasmosis?
- Caused by Toxoplasma gondii which is a protozoan found in cat faeces, soil or uncooked meat
- 1/3 of people in the UK are probably infected with Toxoplasma at some point in their lives
Is toxoplasmosis screening offered?
- NOT offered routinely because it is very rare for babies to be affected
- Little evidence for the benefits of screening
What is some advice about toxoplasmosis prevention?
- Avoiding eating rare or raw meat
- Avoiding handling cats and cat litter
- Wearing gloves and washing hands when gardening or handling soil
What are the clinical features of toxoplasmosis?
How does foetal damage and transmission rate change during pregnancy?
- Initial infection is usually ASYMPTOMATIC or may cause flu-like illness
- Parasitaemia occurs within 3 weeks
- Infection in the first trimester is most likely to cause severe foetal damage but the transmission rate is low (10%)
- In the third trimester, the transmission rates are much higher (85%) but the risk of foetal damage is low (10%)
What are the features of Severely Affected Infants of Toxoplasmosis?
- Ventriculomegaly
- Microcephaly
- Chorioretinitis
- Cerebral calcification
- NOTE: most infants are asymptomatic at birth and develop symptoms later on
What is the management of toxoplasmosis?
`- Diagnosis is made by the Sabin Feldman Dye Test
- NOTE: IgM antibody tests are also available but IgM may persist for months or years after infection
- If an abnormal US raises suspicion of congenital toxoplasmosis, amniocentesis can be performed
- PCR of amniotic fluid is highly accurate for identification of T. gondii
- Spiramycin treatment can be used in pregnancy (3 week course of 2-3 g/day)
- This reduces incidence of transplacental infection
- If toxoplasmosis is found to be the cause of abnormalities on ultrasound, termination of pregnancy should be offered
What is cytomegalovirus?
- CMV is a DNA herpes virus transmitted by the respiratory droplet route and excreted in the urine
- 60% of women are seropositive for CMV when they become pregnant
- 1-2 out of 200 infants in the UK are born with congenital CMV
- Some will have problems at birth (e.g. hearing loss, learning difficulties) and others will be asymptomatic but go on to develop problems later on
- Primary infection is more likely to cause congenital CMV
What are the clinical features of cytomegalovirus?
- Primary infection usually produces no symptoms or mild flu-like symptoms in the mother
- Diagnosis is usually made after abnormalities are seen on the ultrasound
- Features in the foetus
- Growth restriction
- Microcephaly
- Intracranial calcification
- Ventriculomegaly
- Ascites
- Hydrops
- Infants may present later with blindness, deafness or developmental delay
- The neonate can also be anaemic and thrombocytopaenic with hepatosplenomegaly, jaundice and a purpuric rash
What is the management of CMV?
- Serological diagnosis (CMV antibodies in an initially seronegative woman)
- NOTE: IgM can persist for several months so IgM is insufficient to diagnose infection, it has to be a new finding in a woman who was IgM negative at the time of booking
- The amniotic fluid can be tested by PCR
- If abnormalities suggestive of congenital CMV are detected, termination of pregnancy should be discussed
- CMV is a herpes virus, so it can be latent and be reactivated
- It persists in the lymphocytes throughout life
- Reactivation occurs via shedding in the genital, urinary or respiratory tract
What virus causes chickenpox?
What can chickenpox cause?
- Caused by varicella zoster virus (VZV) which is transmitted by droplets and direct personal contact
- Screening is NOT routinely recommended
- Women identified as being seronegative can be considered for vaccination either prepregnancy or in the postnatal period
- It can cause foetal varicella syndrome
What are complications of chickenpox in pregnant women?
- Pneumonia
- Hepatitis
- Encephalitis
- Non-immune pregnant women are more vulnerable to complications of chicken pox
- The mortality rate is 5 times high in pregnant women compared to non-pregnant adults
What is the advice for pregnant women regarding chickenpox?
- Asked whether they have had chickenpox before at the booking visit
- If NOT, be advised to avoid contact during pregnancy
- If they do come into contact with chickenpox, they should seek medical advice ASAP
- Significant contact is defined as being in the same room as someone for 15 mins or more, or face-to-face contacts
- Individuals with the virus are infectious 48 hours prior to the appearance of the rash until the vesicles crust over (around 5 days)
- VZV IgG can be detected to confirm VZV immunity
How should non-immune women with chickenpox be managed?
- Given VZIG as soon as possible
- It is effective when given up to 10 days after contact
- Women should be advised to inform the doctor if a rash develops
How is chickenpox in pregnancy managed?
- Avoid contact with other pregnant women and neonates until the lesions have crusted over
- Aciclovir 800 mg 5/day for 7 days should be prescribed if they present within 24 hours of the onset of the rash and they are > 20 weeks gestation
- VZIG has NO therapeutic benefit once chickenpox has developed
- Hospital admission should be considered if the following risk factors are present: smoking, chronic lung disease, corticosteroids or in latter half of pregnancy
- Women who are hospitalised should be nursed in isolation from babies and pregnant women
- Delivery during the viraemic period may be EXTREMELY HAZARDOUS
- Patients should be given supportive treatment with IV aciclovir
What are the risks of chickenpox in pregnancy?
- Thrombocytopaenia
- DIC
- Hepatitis
- Varicella infection of the newborn