Thrombocytopaenia in Pregnancy

Dr Guan Yong KheeHospital Melaka

Diameter of 1 – 4 μm Cell volume of 2 to 20 fL Young platelets being larger than the older

ones No cell nucleus but has residual mRNA from

the megakaryocytes

Platelets

Giant Platelet

Normal Platelet

Approximately 70 to 80 % of platelets circulate in the blood

20 to 30 % are stored in the spleen Decomposition of platelets takes place in the

spleen and partly in the liver Average life span is 5 to 12 days : mean 7

days

What is the normal platelet count? ? 150-450 x 109/L ?150-300 x 109/L Are there racial differences? Western Vs Asian? Malays Vs Chinese?

Normal Platelet Count

Methods of platelet counting Separation by cell volume – the impedance

measurement principle problematic if platelet sizes are large or there are RBC fragmentations

RNA staining and flow cytometry(Optical method) Might only be available in some higher end analysers

Separation by detection of the membrane receptors CD61 and CD41 complicated and very expensive

Possible inaccuracies in platelet count

Conventionally <150 x 109/L Might be more reasonable to consider it <

100x 109/L Should be confirmed with a peripheral

blood film

What is thrombocytopaenia?

Thrombocytopaenia

What is the minimum platelet number required for normal haemostasis? Some studies say 5/mcl

Threshold for transfusion If febrile, transfuse if platelets < 20/mcl If afebrile, transfuse if platelets < 10/mcl If bleeding, transfuse if < 50 or < 100(if CNS

bleed)

Thrombocytopaenia

Bleeding might not be due to low platelet itself only Usually must rule out other causes of bleeding

Concomitant peptic ulcer disease? Bladder pathology? Cervix or endometrial pathology?

Thrombocytopaenia

Problems with platelet transfusions 1 random unit usually rises the platelet count

by about 10/mcl 1 apheresis unit usually rises the platelet count

by 40-60/mcl Platelet lifespan is short (7-10 days) Transfused platelet’s lifespan is even shorter

(1-2 days) Transfusion might lead to platelet refractoriness

Thrombocytopaenia

Is there a threshold of platelet count to do a BMA? No However, I might want to transfuse platelets if

it is < 20 to avoid a big haematoma if adequate pressure is not applied long enough post BMA at the BMA site

Thrombocytopaenia

Other considerations Low platelet is usually the earliest sign of

DIC Platelets numbers might be underestimated

in TTP/ MAHA picture/ increase RBC fragmentation in certains Acute Leukaemias

Possible to be ITP? Unlikely if there is pancytopaenia

Diagnosis

FBP BMA and Trephine biopsy and other

investigations Immunophenotyping Cytogenetics/ FISH Molecular/ PCR

Diagnosis

Extremely important to guide further treatment

Transfusing without investigating is like filling up a bucket which is leaking

Diagnosis

Possible diagnosis not to be missed Aplastic Anaemia – Transplant emergency Acute Leukaemias - ?APML, ?ALL, ?AML M7 Myelodysplastic Syndrome B12/Folic Deficiencies Hypothyroidism

Normal physiology – platelet counts are platelet counts are lower in pregnancy!!lower in pregnancy!!

Cause for this drop in pregnancy is unknown – proposed theories include dilution decreased platelet production increased platelet turnover during pregnancy

What about the platelet count in Pregnancy?

How common? 6-10% of pregnant ladies

Pregnancy – specific causes of thrombocytopaenia Gestational Thrombocytopaenia Preeclampsia/ Eclampsia HELLP Syndrome Acute Fatty Liver

Thrombocytopaenia in Pregnancy

Other Non- Pregnancy specific causes

Thrombocytopaenia in Pregnancy

MOST COMMON CAUSE OF LOW PLATELETS IN PREGNANCY 70% of cases of low platelets

late 2nd or 3rd trimester Usually mild Unusual for platelets to be < 70 x109/L

Gestational Thrombocytopaenia

Diagnosis of exclusion Might not be possible to differentiate with ITP Might make epidural anaesthesia troublesome

– might need platelet transfusion Does not respond to ITP treatment(ie steroids/

IVIG) Resolved post delivery 1-2 months

Gestational Thrombocytopaenia

Rare – about 5% to 10% of causes of low platelets in pregnancy compared to Gestational

Thrombocytopaenia(70+%) and hypertensive disorders in pregnancies(20+%)

1 in 1,000 to 1 in 10,000 pregnancies

ITP in Pregnancy

Goal of treatment – Prevent Bleeding Treatment is generally not required if

Platelets are > 20-30x109/L Might need to keep it higher if planned LCSC

or for epidural anaesthesia

ITP in Pregnancy

www.moh.gov.my/attachments/3911

Diagnosis – Diagnosis of exclusion BMA usually unnecessary unless suspecting

MDS/Leukaemia/ Lymphoma

ITP in Pregnancy

Management before term (36weeks) Asymptomatic with Plt > 20 x 109/L

No treatment To expect platelets to drop after 36 weeks

Symptomatic or Plt < 20 x 109/L Corticosteroids IVIG

ITP in Pregnancy

Management after 36 weeks Plt > 30 x 109/L (Malaysian CPG) – safe for

vaginal delivery Mode of delivery is always based on

Obstetrics indications (Malaysian CPG) and not platelet counts!!!

ITP in Pregnancy

Management after 36 weeks If Caesarian section is required for obstetric

indications iv corticosteroids if platelet count 30-50 x 109/L IVIG and iv corticosteroids if platelet count <30

x 109/L IVIG and iv corticosteroids plus platelet

transfusion if platelet count <10 x 109/L

ITP in Pregnancy

Management during labour Platelet count above 50 x 109/L is safe for

caesarian section under general anaesthesia Epidural anaesthesia is best avoided If platelet counts < 50 x 109/L and emergency

LSCS is required: Give – IVIG, IV Methylprednisolone immediately Give platelet transfusion just prior to surgery

ITP in Pregnancy

‘Safe’ Platelet Thresholds for delivery• vaginal delivery: > 30 x 109/L• caesarean section: > 50 x 109/L• epidural anaesthesia: > 80 x 109/L

ITP in Pregnancy

Determining if there are any unusual bleeding tendencies ( - deciding if the patient is a so called bleeder or non-bleeder) – careful history taking If non- bleeder and no obstetric risks factors, I

tend to monitor rather than give treatment

ITP in Pregnancy – What I would do…or what I have

learned from my sifus

Determining if the patient is a responder to treatment or not (?full recovery, partial recovery of platelet counts) Careful history and notes review

steroid responsiveness IVIG responsiveness – bear in mind repeated IVIG

might cause refractoriness to IVIG

ITP in Pregnancy – What I would do…or what I have

learned from my sifus

If unsure of treat, I would give a trial of treatment especially for moderate to severe thrombocytopaenia, this is only if there is time to play with…

Early in pregnancy – trial of steroids Still time but Limited – trial of IVIG

ITP in Pregnancy – What I would do…or what I have

learned from my sifus

If treatment responsive and indeed platelet drops nearing term I would start steroids and anticipate an

increase from about 1-2 weeks I would start IVIG and anticipate an increase in

from 3-5 days but likely only lasts about 1-2 weeks

ITP in Pregnancy – What I would do…or what I have

learned from my sifus

Neonatal care Neonatal thrombocytopaenia in pregnant

ladies with ITP is unpredictable NOT correlated to platelet count, maternal

antibodies, or other factors Only Consistently known risks factor is history

of a sibling with neonatal thrombocytopaenia

ITP in Pregnancy

Neonatal care Paediatrician/ Neonatologist should be alerted Platelet count nadir might be 2-5 days post

natal

ITP in Pregnancy

A note about other forms of treatment No evidence about safety, efficacy and thus

not recommended

ITP in Pregnancy

Platelet Analysis Overview, Sysmex Xtra Online, Volume No 2, December 2007

ASH Education Book 2010 - Immune Thrombocytopenia by Adam Cuker and Douglas B. Cines

ASH Education Book 2010 - Thrombocytopenia in Pregnancy by Keith R. McCrae

CLINICAL PRACTICE GUIDELINES – MANAGEMENT OF IMMUNE THROMBOCYTOPENIC PURPURA, August 2006, MOH/P/PAK/115.06 (GU)

References

Thank you