Haematological/immunological changes in pregnancy Flashcards
• As trophoblast invades decidua-
- increase in uterine Natural Killer (NK) cells and dendritic cells- allow re-modelling of uterine wall rather than cytotoxic or antigen presenting function. Macrophages prominent too.
- very infrequent lymphatic channels, minimal lymphoid tissue
Physiological changes in pregnancy
- RBC decline
- White blood cell numbers rise
- Fall in platelets
- rise in MCV
- Rise in fibrinogen and factors VIII, IX, X so hyper coagulable state
Anaemia in pregnancy
• Increased demands of foetus iron def anaemia
- check ferritin (MCV may be “normal”)
• Common to supplement iron in pregnancy but constipation/abdo pain/nausea common- IV iron eg Ferinject is an option
folic acid in pregnancy
educe neural tube defects (neural tube formed in 2-4 weeks from conception)
Immune thrombocytopenic purpura (ITP)
purple rash
- is an autoimmune disease of children and adults
- may be triggered by infection, drug or pregnancy -auto antibodies to platelets (marrow normal)
- treated by watch and wait/ steroids/ immunoglobulins/ splenectomy/ drugs to mimic thrombopoetin
- may need treatment to achieve platelets of 50+ for labour
- some risk of neonatal thrombocytopenia due to IgG antibodies crossing placenta
Thrombotic thrombocytopenic purpura (TTP)
• Rare but life-threatening “thrombotic microangiopathy”
• Enzyme (ADAMS13) prevents large Von Willebrands polymers- this becomes
deficient and platelets aggregate • Presents as fever, neurological
and renal disease, low platelets
and fragmented red cells. Coagulation screen usually normal
how would you treat Thrombotic thrombocytopenic purpura (TTP)
- Can be associated with auto-immune disease/HIV/pregnancy
* Treated by plasma exchange (to replace enzyme
when Is high risk of death in pregnancy - pulmonary embolism
during the pregnancy and 6 weeks postpartum
what are additional risk factors for birth complications
- previous clot -smoking -twins -obesity
- thrombophilia eg anti-thrombin deficiency
Thromboembolic disease
- In late pregnancy, pelvic veins compressed (L>R) leg swelling
- Progressive pain, tenderness, unilateral swelling- ?DVT
- Doppler exam of leg
- Chest X ray- if abnormal then CT pulmonary angiogram (higher radiation dose) more reliable than ventilation/perfusion scan
how would you treat Thromboembolic disease
• Low molecular weight heparin (LMWH) is treatment of choice
• Increase rate of clearance and volume of distribution requires twice
daily dose
• Monitoring of anti Xa levels (3-4 hours post dose) required to show effective dosing
• Will need prophylactic anticoagulation in future pregnancies
Pre-eclampsia (PET)
hypertension, fluid retention, proteinuria, headache, urate high • A minority of patients with PET will develop HELLP
HELLP syndrome
evidence of haemolysis- anaemia -red cell fragments - raided LDH also, raised liver enzymes (ALT/AST), low platelets
treatment for both PET and HELLP
Treatment- prompt delivery of baby and supportive care
Disseminated intravascular coagulation (DIC)
• Acute and serious complication typically following- -placental abruption
-amniotic fluid embolism
-dead foetus
Typically haemorrhagic, very unwell, organ failures, depletion of coag factors, low platelets, red cell fragments
What is the treatment for Disseminated intravascular coagulation (DIC)
treating the cause, coagulation factors and platelets
risk factors for major haemorrhage
placenta praevia (over cervix)
-placental abruption
-retained products of conception
- poor uterine contraction after delivery
Important to recognise excessive blood loss- treat the cause and replace red cell/platelets/coagulation factors
Screening criteria- Wilson and Jungner-1
- Recognisable latent or early symptomatic stage
- A simple test with high sensitivity and specificity
- This test should be acceptable to the population
- Early effective treatment needs to be of clear benefit • Agreement as to who should be treated
• Haemoglobin needs -
- Hb A (adult) = 2 alpha, 2 beta
- Hb A2= 2 alpha, 2 delta
- Hb F (foetal)= 2 alpha, 2 gamma
Detection of haemoglobinopathy/thal carriers
• Abnormal haemoglobins will show on electrophoresis/HPLC
