Maternal medicine Flashcards
In beta thalassaemia, what is used for monitoring of sugar control?
HbA1C - under reads due to defective global chains and transfusions
Serum Fructosamine used instead
Should be <300 for 3 months prior to conceiving (equivocal to HbA1c 43)
What are the cardiac requirements in pregnancy for women with beta thalassaemia?
Ideally no cardiac iron but this can take years to achieve in prenatal planning
Otherwise, aim for cardiac T2* > 20 ms (on cardiac MRI) wherever possible as this reflects minimal iron in the heart.
A T2* < 10 ms is associated with an increased risk of cardiac failure.
Note that reduced ejection fraction is a relative contraindication to pregnancy
Cardiac failure accounts for 50% of deaths in patients with B-thal
What is target dry weight of iron for the liver in b-thal?
7mg/g
If exceeds 15 , then need to start iron chelation therapy in second to third trimester to reduce risk of cardiac overload of iron
(desferrioxamine)
What iron chelators are safe in pregnancy?
Limited safety data
Use of desferrioxamine between 20-28 weeks where necessary
deferasirox and deferiprone should be stopped 3 months before pregnancy
OK post-natally
What special precautions should be taken for splenectomy patients?
Daily penicillin or erythromycin to protect against encapsulated organisms Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae type b.
Haem IB and Menc C vaccines if not already had
What is recommended schedule of scans in pregnancy for b-thal?
Early scan 7-9 weeks
Growth scans from 24 weeks (4 weekly)
What is the management of transfusions for patients with b-thal in pregnancy?
Continue transfusions with target of Hb >100
Transfused 2-3 units, 2 weekly as required - will fall at different rates depending on patient
If Hb >80 at 36 weeks then can avoid further transfusion until after delivery
What are VTE requirements of b-thal in pregnancy?
Splenectomy AND platelets > 600 - LMWH and Aspirin
Splenectomy OR platelets >600 - Aspirin
When IP - LMWH
What are the recommendations for intrapartum care of b-thal?
Continuous CTG
Not an indication for C/S
Iron chelation (stress response of labour) 2g over 24 hours
Active 3rd stage
Riks of transmission of Parvovirus
Risk of vertical transmission
<15 weeks gestation - 15%
15 - 20 weeks - 25%
Term - 70%
Risk of fetal infection is negligible after 20 weeks
7 days incubation on average
Risk of fetal death 5-10% of infected fetuses
What time of virus is varicella?
What is incubation time and infectivity?
Varicella (chickenpox) is a DNA virus
Incubation 1-3 weeks
Infections from 48 hours before rash appears to after the vesicles crust over - typically about 5 days
Should you be vaccinated against varicella in pregnancy?
Not during but safe prepregnancy or postpartum
Safe whilst breastfeeding
Live attenuated vaccine
What are the criteria for receiving VZIG?
Made from donated blood products - limited resource
If significant exposure in pregnant woman offer as soon as possible for up to 10 days after contact
Significant exposure: contact in the same room for 15 minutes or more, face-to-face contact or contact in the setting of a large open ward.
Non-immune pregnant women who have been exposed should be treated as infective between days 8-28 following exposure or days 8-21 if had VZIG
What are maternal risks of varicella in pregnancy?
What is treatment?
Affects 0.3% of pregnancies in UK (most women immune)
Pneumonia - around 5%
Hepatitis
Encephalitis
If presents within 24 hours of rash - oral aciclovir 800mg 5 times/day for 7 days
IV aciclovir if severely unwell
Discuss timing of delivery in varicella
Ideally at least 7 days after onset of rash
Risks: disseminated disease, thrombo/coagulopathy, neonatal transmission
Sometimes indicated if severely unwell
What are the fetal implications of varicella in pregnancy?
No known increased risk of miscarriage
If before 28 week then increased risk of fetal varicella syndrome
FVS: skin scarring in a dermatomal distribution; eye defects (microphthalmia, chorioretinitis or cataracts); hypoplasia of the limbs; and neurological abnormalities (microcephaly, cortical atrophy, mental retardation or dysfunction of bowel and bladder sphincters).
It does not occur at the time of initial fetal infection but results from a subsequent herpes zoster reactivation in utero and only occurs in a minority of infected fetuses.
See FMU at 16-20 weeks or 5 weeks after initial infection
If infection in last 4-5 weeks of pregnancy then risk of neonatal varicella - 50% affected, 25% clinical varicella (chickenpox)
What is the method of inheritance for haemophilia ?
Haemophilia A (Factor VIII) and B (Factor IX) are both X-linked
If mother is a carrier then son has 50% chance of being affected and daughter 50% of being carrier
40-50% of haemophilia is de novo mutation
Therefore, new cases of severe haemophilia usually arise from mutation during spermatogenesis in the maternal grandfather, conferring obligate carrier status on the mother. This theory is correct in 90% of cases and thus, the risk to the next male baby after a spontaneously affected sibling is 45%.
How is severity of haemophilia assessed?
Severity is categorised according to the plasma concentration of factor VIII or IX.
Severe <0.01 iu/ml
Moderate haemophilia 0.01–0.05 iu/ml
Mild haemophilia, 0.06–0.40 iu/ml.
What is the cut off of factor VIII/IX for obstetric procedures in haemophilia?
0.5iu/ml is needed for
Amnio/CVS
Any surgical procedure
Epidural/spinal
Aim for factor VIII/IX levels of at least 0.5 iu/ml to cover surgical or invasive procedures, or spontaneous miscarriage. If treatment is required, factor levels of 1.0 iu/ml should be aimed for and not allowed to fall below 0.5 iu/ml until haemostasis is secure
What are treatment options in the antenatal period for haemophilia?
Tranexamic Acid
DDAVP (Desmopressin - diuretic effect) only for Haemophilia A, not in PET
Recombinant factors
How do levels of factor XIII and IX change during pregnancy?
Synthesis of factor VIII is increased in pregnancy with plasma levels rising from 6 weeks of gestation to two to three times the baseline by term.
Factor IX levels are relatively unaltered
What considerations need to be taken into account during labour for babies predicted to have haemophilia?
Avoid:
ECV
FSE/FBS
Midcavity forceps or ventouse
From GTG: Low-cavity forceps may be used and are likely to be preferable to caesarean section in the second stage of labour.
Active management of 3rd stage
Give TXA in labour
Levels of factor VIII/IX should be maintained above 0.5 iu/ml for at least 3 days following an uncomplicated vaginal delivery or 5 days following instrumental delivery or caesarean section.
TXA should be continued postpartum until lochia is minimal.
LMWH should generally be avoided where the factor level is 0.6 iu/ml or less, but will need to be considered in women with thrombotic risk factors, with careful balance of risks.
What are neonatal considerations with haemophilia?
Offer all male born foetuses cord blood testing if born to known female carriers
- may need retesting at 3/6 months
Administer Vitamin K orally if low factor levels
Consider cranial US/MRI
Factor VIII - same as adult level
Factor IX - 1/2 of adult level
What is mechanism of inheritance for von willebrand disease?
Dependent on type
Type 1 - partial reduction in amount of vWF
Type 2 - Dysfunctional vWF, dominant inheritance
Can have thrombocytopenia with DDAVP treatment, generally avoided
Type 3- large reduction in amount of vWF, recessive inheritance
What are the risks of von willebrand disease in pregnancy?
Increased risk of:
APH x 10 risk
Primary PPH occurs in 15–30% of women
Secondary PPH occurs in approximately 25%.
Need for blood transfusion is increased x5
Mortality rate is increased x10
Avoid IM injections and NSAIDs
What is the incidence of Factor XI deficiency?
The incidence in the non-Jewish population is 1/1 000 000
it is common in Ashkenazi Jews with heterozygosity in 8% and homozygosity in 0.2–0.5%.
Autosomal inheritance, worse symptoms of homozygous/compound heterozygous - not always know by patient
Spontaneous bleeding is rare - but risk with surgery/procedures
There is poor correlation between factor level and bleeding tendency
What is the role of Factor XI in the clotting pathway?
Factor XI is a glycoprotein that plays a role in the amplification of the coagulation process after the initial production of thrombin.
What are treatment options for Factor XI deficiency?
Treatment options include tranexamic acid, factor XI concentrate and FFP
Don’t give TXA and Factor XI together
Avoid neuroaxial analgesia
What is Bernard Soulier Syndrome?
BSS is caused by quantitative or qualitative deficiency of the membrane GP Ib-IX-V complex, leading to abnormal adhesion of platelets
Autosomal recessive
Thrombocytopenia and large platelets
Risks: PPH, wound haematoma,
Management: TXA, Platelet transfusion
Avoid neuraxial anaesthesia
What is Glanzmann’s thrombasthenia (GT)?
GT is caused by lack of or nonfunctioning GP IIb/IIIa due to missense mutations in ITGA2B and ITGB3. Platelet–platelet aggregation is impaired
Risks
MATERNAL
Intrapartum bleeding/PPH
FETAL
Risk of alloimmunisation from platelet transfusions or paternal derived complexes
May cause fetal thrombocytopenia/ICH
If present, manage through MU - consider steroids or IVIG
Avoid vit k following delivery until status known
What is the incidence of postpartum psychosis?
1-2 in 1000
1 in 4 if Bipolar
<1 in 2 if bipolar and family history/personal history
Typically presents day 1-3
What are the implications for rubella in pregnancy?
Rubella: single stranded RNA toga virus
Live attenuated vaccine (contraindicated in pregnancy)
If caught in first trimester 90% chance of transmission to fetus
Incubation around 2 weeks
20% of miscarriage
Congenital rubella syndrome: teratogenic with poor prognosis and significant complications (sensorineural deafness, cataracts and cardiac abnormalities most common)
No specific treatment in pregnancy
What is the incubation period for Parvovirus?
Parvovirus B19 - slapped cheek
Upto 50% adults asymptomatic and do not require treatment
Incubation 7 days before rash onset and 1 day after
Arrange urgent referral to a specialist in fetal medicine for serial fetal ultrasound scans and Doppler assessment to detect fetal anaemia, heart failure, and hydrops
Risk of vertical transmission
<15 weeks gestation - 15%
15 - 20 weeks - 25%
Term - 70%
What are the implications of uncontrolled hyperthyroid in pregnancy?
High miscarriage rate
Intrauterine growth restriction (IUGR)
Low birth-weight baby
Stillbirth
Neonatal thyroid dysfunction
What is the management of potential exposure to Zika virus in pregnancy?
If pregnant woman’s partner travelled to Zika area - barrier methods rest of pregnancy
If symptomatic within 2 weeks of exposure, or after sexual contact with someone who has been exposed within 2 weeks:
-Refer for baseline USS assessment
-If feeling unwell or has felt unwell, test for ZIKA antibodies by sending serum (and urine if within 21 days of symptoms) to RIPL
-If positive Zika or abnormal USS refer to FMU
What type of Virus is Zika?
Flavivirus
Single stranded RNA virus
Transmitted primarily by Aedes mosquitos (daytime)
Can be transmitted sexually but risk is low
Incubation period 3-12 days
Typical symptoms: fever, maculopapular rash, arthralgia or conjunctivitis
Rash usually resolves within 2 days but may persist up to 1 week
Many asymptomatic
Zika associations:
Guillan Barre syndrome
Congenital microcephaly* (<2.5th centile)
Other congenital abnormalities
What is the impact of pregnancy on seizure frequency, for women with epilepsy?
2/3 No deterioration in seizure frequency
Generalised epilepsy more like to remain seizure free than focal
Most important factor in predicting deterioration is seizure-free duration pre pregnancy
What considerations should be made for women with epilepsy in antenatal and intrapartum periods?
Antenatal -
Consultant led care, ANC, serial growth, high dose folic acid
Intrapartum -
If high risk of seizure in Labour consider Clobazam prophylactically
No pethidine/carbetocin
Terminate seizures ASAP to reduce risk fetal acidosis
Delivery on CDS
What is the risk of a tonic-clonic seizure during the labour and the 24 hours after birth?
1-4%
Higher in post-natal period
What is the impact of pregnancy on myasthenia gravis?
Myasthenia Gravis (MG) is an autoimmune disease caused by antibodies against the nicotinic acetylcholine receptor or other postsynaptic antigens
Female:Male ratio 2:1
Typically presents age 20-30
Effect of Pregnancy on Maternal MG
Symptoms worsened for 40%*
Symptoms unchanged in 30%
30% had remission
No evidence that MG adversely affects pregnancy outcomes
Effect of Pregnancy on Neonate
Transient neonatal MG (TNMG) effects approx 20% of infants born to MG mothers
Transient neonatal MG is due to transfer of maternal antibodies (IgG anti‐AChR antibodies)
*Exacerbations typically occur in the first trimester and in the first 3 months postpartum
Management considerations
Starting glucocorticoid therapy or withdrawing immunosuppressant therapy may exacerbate MG
Infections require prompt treatment as may cause exacerbation
Pregnant patients with MG should be assessed for baseline motor strength, pulmonary function and ECG
Thyroid function tests advised. Thyroid dysfunction in 10-15%
Approx 15% of persons with MG have thymoma
Patients with thymoma who have not undergone thymectomy present with a higher incidence of exacerbation during pregnancy and higher risk neonatal MG
Thymectomy should be considered before conception or after delivery (not during pregnancy)
MG most commonly caused by IgG anti‐AChR antibodies. Patients with anti‐MuSK antibodies generally have worse clinical symptoms and TNMG
TNMG
Affects 20% of babies
Infants with TNMG typically develop symptoms within 12 h to 4 days of delivery
Symptoms resolve spontaneously after 3-4 weeks due to antibody degradation
What is the incidence of Diabetes Insipidus in pregnancy?
2-4 in 100,000
Normalyl arises in 3rd trimester and resolves 4-6 weeks post-natal
PET/HELLP can cause DI to develop
Avoid spinal as can cause rapid shift in BP - epidural OK
Discuss management of malaria in pregnancy
Classify as complicated or uncomplicated
Uncomplicated is defined as <2% parasitised red blood cells in a woman with no signs of severity and no complicating features
Complicated/severe >2% parasitised red blood cells or complicating features e.g. respiratory distress, pulmonary oedema, hypoglycaemia, secondary gram negative sepsis
Diagnosis confirmed with blood films
Management
-Admit to hospital
-If uncomplicated,
P. falciparum/mixed Quinine and Clindamycin
P. vivax Chloroquine
P. ovale Chloroquine
P. malariae Chloroquine
-If complicated - admit to ITU
IV artenusate or Quinine
-Monitor signs of hypoglycaemia with quinine
Primaquine should not be used in pregnancy.
What is the incubation period of rubella?
14 days
