Congenital abnormalities and infections in pregnancy Flashcards
Congenital abnormalities come under which 5 categories?
- Structural deformities
- Chromosomal abnormalities
- Inherited diseases
- Intrauterine infection
- Drug exposure
Give an example of a structural deformity causing congenital abnormality
Diaphragmatic hernia
Give an example of a chromosomal abnormality causing congenital abnormality
Down’s syndrome
Give an example of an inherited disease causing congenital abnormality
CF
Give an example of an intrauterine infection causing congenital abnormality
Rubella
Give an example of a drug exposure causing congenital abnormality
Antiepileptics (sodium valproate)
What is the difference between screening and diagnostic tests?
Screening test:
- available for all women
- measures risk of fetus being affected by a disorder
- high risk patient then offered a diagnostic test
Diagnostic test:
- only for high risk women to confirm or refute possibility (aka Down’s syndrome y/n)
What are methods of prenatal testing for congenital anormalities?
Non-invasive:
Maternal blood testing
USS
Fetal MRI
Invasive:
- Amniocentesis
- CVS
Which maternal blood markers can be used to test for chromosomal abnormalities?
B-HCG PAPP-A AFP Oestriol Inhibin A
Free fetal DNA (NIPT)
What can NIPT show?
Whether mother is carrying a fetus with aneuploidy
Done by scanning for free fetal DNA in mother’s bloodstream
_____ scan is used to determine the gestation, pregnancy site and exclude multiple pregnancy
USS
What specific aspect does USS look for to exclude congenital abnormalities?
What indicates a higher risk?
Nuchal translucency
Larger NT = higher risk of congenital abnormalities
When is the NT scan done with USS?
Between 11 and 13+6 weeks
What does the anomaly scan involve?
When is it carried out?
Look for structural abnormalities
Carried out at 20 weeks (picks up stuff not caught by NT scan)
When is fetal MRI used?
Aid diagnosis of intracranial lesions
Differentiate different types of soft tissue (liver/lung)
When is amniocentesis performed usually?
15 weeks + gestation
What can amniocentesis detect?
Chromosomal abnormalities
Infections (CMV, toxoplasmosis)
Inherited disorders (Sickle cell anaemia, thalassemia, CF)
How is CVS similar and different to amniocentesis?
Same uses as amniocentesis.
Allows results much earlier (11 weeks)
Miscarriage rate slightly higher
How can samples screening for congenital abnormalities be tested
FISH
PCR
Karyotyping
Micro-array-CGH (Comparative genomic hybridisation)
What fertilisation method does preimplantation genetic diagnosis require?
IVF (even in fertile couples)
What are the 2 best known examples of Neural tube defects?
Spina bifida
Anencephaly
What supplement can be given to prevent NTDs?
When is this typically recommended to be taken?
Folic acid
Preconceptually
Which chromosomal abnormalities are usually screened for?
Down’s syndrome (T-21)
Edward’s syndrome (T-18)
Patau’s syndrome (T-13)
Klinefelter’s 47 XXY
Turner’s syndrome 45 X0
What are 2 risk factors for down’s syndrome?
High maternal age
Previous affected baby
What would be seen on USS with Down’s syndrome?
Thickened nuchal transluceny Structural abnormalities Absent/short nasal bone Tricuspid regurg Severe FGR
What would be expected for the following bloods in a Down’s syndrome pregnancy? (higher/lower)
- PAPPA
- B-HCG
- AFP
- Oestriol
- Inhibin
- PAPPA - lower
- B-HCG - higher
- AFP - lower
- Oestriol - lower
- Inhibin - higher
What characteristic appearance is seen with anencephaly on USS?
“Frog-eye” appearance
+ Absent cranium
When are NT defects usually picked up on scans?
USS @ 20 weeks (anomaly scan)
Can increased nuchal translucency indicate cardiac defects?
Yes
What in-utero therapy can be given to fetuses with cardiac defects?
(Medical/Surgical)
Medical - antiarrythmics
Surgery - Valvoplasty for critical aortic stenosis
What drug class is used to treat polyhydramnios?
NSAIDs
What kind of surgery is used to repair NTDs in utero?
Open surgery
______ is characterised by a partial extrusion of the abdominal contents in a peritoneal sac.
50% of affected infants have a chromosomal problem and thus amniocentesisi is offered.
Exomphalos
_______ is characterised by by free loops of bowel in the amniotic cavity and is rarely associated with other abnormalities.
Gastroschisis
What is the link between MMR vaccine and pregnant women?
MMR is live vaccine - should not be given to pregnant women.
Give to non-immune women AFTER giving birth.
What are the 4 classic features of congenital rubella syndrome?
Congenital deafness
Congenital cataracts
Congenital heart disease (PDA + pulmonary stenosis)
Learning disability
Chickenpox is caused by which virus?
VZV
What can chickenpox in pregnancy lead to?
Severe cases of pneumonitis/hepatitis/encephalitis
Fetal/neonatal varicella infection
What blood test is used to test for immunity against VZV?
IgG levels for VZV
Positive = VZV immunity
What can be given to pregnant women who are non-immune to VZV as protection?
IV varicella immunoglobulins
What are the 5 features of congenital varicella syndrome?
FGR
Microcephaly, hydrocephalus, learning disability
Scars and significant skin changes in dermatomes
Limb hypoplasia
Cataracts + inflammation in eye (chorioretinitis)
Which infectious gram-positive bacteria is many more times likely in pregnant women than non-pregnant people?
Listeria monocytogenes
How can pregnant women with listeria present?
Asymptomatic
Flu-like illness
Or rarely, pneumonia, meninoencephalitis
Why is listerosis in pregnant women considered dangerous?
High rate of miscarriage or fetal death
Severe neonatal infection
How is listeria typically transmitted?
Unpasteurised dairy products, processed meats, contaminated foods
What advice can be given to pregnant women to protect against listeria?
Avoid blue cheese (high risk foods) and practice good food hygiene
How can rubella virus present in children?
Mild febrile illness with macular rash
What micro-organism causes syphillis?
Treponema pallidum
How can fetal damage from syphillis be prevented?
Benzylpenicillin
How is toxoplasmosis transmitted?
Contamination with faeces from a cat that is the host of a parasite.
Or eating infected meat
What is the classic triad of features in congenital toxoplasmosis?
HIC
Hydrocephalus
Intracranial calcification
Chorioretinitis (inflammation of the choroid and retina in the eye)
What drug is used against toxoplasmosis?
How can toxoplasmosis be managed conservatively?
Spiramycin
Give advice to mother to wash hands after contact with cat litter
What is the distinguishing feature seen on microscopy of CMV?
Owl’s eye inclusion bodies
How is CMV usually spread?
Infected saliva or urine of asymptomatic children.
What are the features of congenital CMV?
FGR Microcephaly Hearing/vision loss Learning disability Seizures
*Most cases of CMV in pregnancy do not cause congenital CMV
How is CMV managed in pregnant women?
No prenatal treatment
Close monitoring for USS abnormalities
Offer termination :(
Vaccination NOT available :(
Which herpes type causes genital warts more commonly?
HSV-2
A mother recently acquired HSV-2 and is due to give birth soon. How should she be managed?
C-section if genital lesions from primary attack present. Ideally within 6 weeks.
Daily aciclovir in late pregnancy to reduce recurrence at term.
Exposed neonates should be given aciclovir too.
Pre-eclampsia and GDM are higher in women with what viral infection?
HIV
HIV can lead to what effects on the fetus?
Stillbirth
Growth restriction
Prematurity
At which stages is HIV transmission greater?
Early and late stage disease.
When CD4 count low and viral load count high.
How is HIV checked for in pregnant women in the UK?
Screening done regularly on HIV+ve women.
Regular CD4 and viral load tests
Which opportunistic infection of HIV+ve women is prophylaxis given against in pregnant women?
Pneumocystic carinii Pneumonia
What is the ideal treatment for HIV?
HAART
Highly active antiretroviral therapy - on mother throughout pregnancy and delivery and on neonate in the first 6 weeks.
Nevirapine *in 3rd world countries
Avoid breastfeeding
What are barriers to HIV protection in 3rd world countries?
Lack of knowledge of HIV status (poor testing/education)
Poor access to healthcare
Slapped check syndrome is caused by which virus?
Parvovirus B19
How long does slapped cheek syndrome last for?
Rash and symptoms last for 1-2 weeks. Self-limiting illness.
Where does slapped cheek syndrome present on the body?
Bright red diffuse rash on both cheeks.
Reticular mildly erythematous rash on trunk + limbs - raised, itchy
Why does fetal anaemia occur with parvovirus B19?
Suppression of erythropoesis in the fetal bone marrow/liver.
Anaemia -> heart failure/hydrops fetalis
What is a complication in the 1st/2nd trimesters from parvovirus B19?
Severe fetal anaemia
What are women suspected of parvovirus infection tested for?
IgM to parvovirus (acute infection?)
IgG to parvovirus (long term immunity after previous infection?)
Rubella antibodies (as differential diagnosis)
How are women with parvovirus managed?
Supportive treatment only.
Scan mothers regularly for anaemia.
If severe hydrops found, in utero transfusion given.
How is Hep B transmitted?
Blood products or sexual activity
How is Hep B checked for in pregnant mothers in the UK?
Maternal screening is routine in the UK for Hep B.
*Hep-C screening restricted to high-risk groups - e.g. HIV positive.
What are risk factors for Hep C infection?
Drug abuse and sexual transmission
Which Hepatitis type leads to chronic hepatitis in 80%?
Hep C
How are Hep C women managed?
None existing
Screen high-risk groups - e,g. HIV+ve women
How are Hep B women managed?
Antivirals for high viral load women
Handle sensitively to avoid transmission to staff
Neonatal immunisation
Which streptococcus must be checked for in mothers and neonates?
Group B Strep (Strep agalactiae)
When does Group B Strep usually infect fetuses?
During labour after ROM
More likely in:
preterm labour
prolonged labour
maternal fever
How can fetal mortality due to Group B Strep be prevented?
High dose IV penicillin throughout labour
Why is screening for Group B Strep not recommended in the UK?
Due to fears of anaphylaxis and also the low incidence of GBS in UK.
