Disorders in pregnancy 4 Flashcards
What is sickle cell disease?
• Recessive disorder due to abnormal beta-chain formation (S chain)
Hb electrophoresis now performed in the UK on all pregnant women
• Maternal complications in pregnancy include
o Acute painful crises (35%)
o Pre-eclampsia
o Thrombosis
• Foetal complications in pregnancy include
o Miscarriage
o IUGR
o Preterm labour
o Death
What is the management for sickle cell disease in pregnancy?
o Hydroxycarbamide is probably teratogenic and so stopped
o Penicillin V is continued
o High dose folic acid
o Aspirin & LMWH are often indicated
o Monthly urine culture
o Iron is avoided to prevent overload
• Crises are managed with hydration, analgesia and often antibiotics & anti-coagulation- USS every 4 weeks and delivery normally indicated by 38 weeks
What is alpha thalassaemia?
results from impaired synthesis of the alpha chain in the Hb molecule
4 genes are responsible for a chain synthesis – individuals with all 4 gene deletions die in utero, those with 3 gene deletions have lifelong requirement for transfusions and those with 1 or 2 deletions are carriers and usually will with mild anaemia
South-East Asian origin
What are beta thalassaemias?
results from impaired synthesis of the beta chain in the Hb molecule
recessive disorder and the heterozygous state of on defective chain causes little illness, although a chronic anaemia which can worsen during pregnancy homozygous beta thalassaemia in pregnancy is rare in the UK
South-East Asian origin and Mediterranean ancestry
What are the complications of thalassaemias?
Monitor effects of iron overload- hepatic & cardiac dysfunction, endocrine disease (thyroid & parathyroid) and diabetes
• Maternal complications- fertility is reduced, liver disease, cardiac failure and diabetes
• Foetal complications- growth restriction and foetal demise are more common, prenatal diagnosis is offered if the partner is heterozygous for either the beta or alpha form
• Preconceptual planning is crucial- primarily because chelation therapy is probably teratogenic and avoided in 1st trimester- Desferrioxamine can be used after this time- USS is used 4 weekly
What is female genital mutilation?
partial or total removal of the external female genitalia or injury to the female genital organs for non-medical reasons
o Type 1: clitoridectomy – partial or total removal of the clitoris or of the prepuce
o Type 2: excision – parital or total removal of the clitoris and labia minora ± labia majora
o Type 3: infibulation – narrowing of the vaginal opening by cutting and repositioning the labia, with out without removal of the clitoris
o Type 4: other – all other non-medical procedures to the female genitalia for non-medical purposes
What are the complications of FGM?
o Pain o Bleeding o Infection o Urinary retention o Damage to pelvic organs o Death
What are the longer term complications of FGM?
o Failure to heal o Urinary tract infections o Difficulty urinating or menstruating o Chronic pelvic infection o Vulval pain due to cysts or neuromas o Pain during sex o Infertility o Fistula o Severe perineal trauma during childbirth
What is red blood cells isoimmunisation?
occurs when the mother mounts an immune response against antigens on foetal red cells in her circulation- the resulting antibodies then cross the placenta and cause foetal red cell destruction
the principal antibodies affecting the foetus are anti-c, anti-E and anti-Kell (a non-Rhesus antibody)
What are the rhesus blood groups?
o C/c
o D/d
o E/e
• An individual inherits one allele of each pair from each parent in a Mendelian fashion, the most significant in isoimmunisation is the D gene
• Only individuals who are DD or Dd express the D antigen and are ‘D Rhesus +ve’
people who have dd are ‘D
Rhesus –ve’ and their immune systems will recognise the D antigen as foreign if they are exposed to it
How us haemolytic disease of the newborn prevented?
administration of exogenous anti-D to the mother: mops up the foetal RBCs that have crossed the placenta by binding to their antigens, thereby preventing recognition by the mother’s immune system
• Routine NIPT for foetal Rhesus type, using maternal blood
• Anti-D should be given to all women who are Rhesus –ve if foetal status is unknown or the baby is Rhesus +ve at 28 weeks
Neonates blood group checked
a Kleihauer test to assess the number of foetal cells in the maternal circulation is performed within 2hrs of birth to detect occasional larger fetomaternal haemorrhages that require larger doses of anti-D to ‘mop up’
When else is anti-D given?
within 72hrs of a sensitising event including miscarriage or threatened miscarriage after 12 weeks, if the uterus is instrumented (ERPC), termination of pregnancy or ectopic pregnancy, it is also given after in utero procedure, such as amniocentesis and ECV, foetal death or antepartum haemorrhage
What are the manifestations of rhesus disease?
- In mild disease- may lead to neonatal jaundice only or sufficient haemolysis to cause neonatal anaemia (haemolytic disease of the newborn)
- More severe disease causes in utero anaemia- as this worsen it causes cardiac failure, ascites and oedema (hydrops), foetal death follows
- Rhesus disease usually worsens with successive pregnancies as maternal antibody production increases
How are the risks of foetal haemolysis identified?
• Foetal rhesus status- unsensitised women are screened for antibodies at booking and at 28 weeks gestation
• Maternal antibody level if anti-D levels are <10IU/ml and there is no previous history of an affected baby, a significant foetal problem is very unlikely and levels are subsequently checked every 2-4 weeks, when anti- D levels are >4IU/ml the foetus is investigated for anaemia using USS
if there is previous history of foetal effects, antibody levels are less predictive
How is the severity of foetal anaemia assessed?
assessed using USS- Doppler USS of the peak velocity in systole of the foetal MCA has a high sensitivity for significant anaemia before 36 weeks- it is used at least fortnightly in at-risk pregnancies
• Very severe anaemia (<5g/dL) is detectable as foetal hydrops or excessive foetal fluid- foetal blood sampling is performed under USS using a needle in the umbilical vein at the cord insertion in the placenta or in the intrahepatic vein
• The risk of foetal loss is 1% and after 28 weeks it should be performed with facilities for immediate delivery if complications arise
