الفهرس 
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Abstract
Thrombocytopenia is defined as a platelet count less than
150,000/mm3. Thrombocytopenia, or a low blood platelet
count, is encountered in 7-8% of all pregnancies with normal
platelet function; thrombocytopenia is rarely the cause of
bleeding unless the count is less than 50,000/mm3.
Thrombocytopenia should always be confirmed by examination
of a peripheral smear. It can be caused by decreased platelet
production, increased destruction, sequestration, or a
combination of these causes (Francisca & Jose, 2006).
The normal platelet count in adults ranges from 150,000
to 450,000/mm3, with mean value of 237,000 and 266,000/mm3
in male and female respectively (buckley et al., 2000).
Primary hemostasis begins when platelets adhere to the
site of endothelial disruption, leading to platelet clumping. This
is followed by platelet activation, which is characterized by
release of granules containing von Willebrand factor, adenosine
5’-diphosphate (ADP), and serotonin. This serves to recruit
other platelets into the growing platelet plug, which acts to stop
the bleeding. Simultaneously, the synthesis of thromboxane A2
and release of serotonin leads to vasoconstriction to reduce
blood loss at the site of vascular injury (Bonnefoy et al., 2006). The secondary hemostatic phase begins when the
coagulation pathway is activated on the surface of the activated
platelets to form a fibrin meshwork, which serves to reinforce
the platelet plug (Andre et al., 2000).
Average platelet count in pregnancy is decreased
(213,000/mm3 vs 250,000/mm3) change in platelet count is due
to haemodilution, increased platelet consumption and increased
platelet aggregation driven by increased levels of thromboxane
A2 (Kadir & Mclintock, 2011).
Classification of thrombocytopenia in pregnancy is
arbitrary and not necessarily clinically relevant:
· Mild thrombocytopenia is 100,000-150,000/mm3.
· Moderate thrombocytopenia is 50,000-100,000/mm3
· Severe thrombocytopenia is >50,000/mm3 (magan &
martin, 1999).
In normal pregnancies, 7.6% of women present with mild
thrombocytopenia during pregnancy, and 65% of them will not
be associated with any pathology. Any pregnant patient with a
platelet count of less than 100,000/mm3 should undergo further
clinical and laboratory assessment (Kadir & Mclintock, 2011). If the platelet count is found to be low, it is important to
confirm this finding as automated counters can be unreliable,
especially at lower platelet counts. A manual count should be
undertaken as it is not uncommon to find the platelets are
clumping and the count is really greater than calculated
(Solanki & Blackburn, 1985).
The patient history and physical examination are key
components when deciding whether to proceed with a regional
anesthetic in the parturient with thrombocytopenia.
Consultation with a hematologist, preferably before labor, can
also help with assessing the etiology of thrombocytopenia and
determining whether the platelets are functioning adequately. If
there is any history of easy bruising, or if the patient has
evidence of petechiae or ecchymosis, regional anesthesia should
not be offered. If the patient has no bleeding history, then our
general practice is to obtain at least one additional platelet count
as close as possible to the time of epidural catheter placement to
ensure that it is not decreasing further. This is especially
important for disease processes that are dynamic, such as
preeclampsia. We do not obtain any bedside tests of platelet
function nor do we have any absolute platelet count cut-off. A
patient with a stable platelet count of 50,000/mm3, as seen in
ITP, is probably at lower risk than one with a platelet count of
75,000/mm3 that is rapidly decreasing, as seen in preeclampsia.
In general this author will place an epidural catheter in a woman with a stable platelet count of approximately
75,000/mm3 and some are comfortable with lower platelet
counts, especially in women with ITP (Douglas, 2001).
There is no absolute cut-off, and the risks of epidural
placement versus general anesthesia must be individualized and
informed consent obtained (quoted from ASA guidelines,
2011).
The practical recommendations for placement a
neuraxial for parturient with thrombocytopenia:
1- Confirm results of low platelet count from an automated
platelet counter with manual platelet count.
2- Consult with hematologist to determine etiology of
thrombocytopenia.
3- Obtain thorough bleeding history and physical
examination focusing on history of easy bruising or
evidence of petechiae or ecchymosis.
4- If history of easy bruising or evidence of active bleeding,
neuraxial anesthesia should not be offered
5- Repeat platelet count close to time of neuraxial
anesthesia placement to assure platelet count is not
rapidly decreasing. 6- Bedside tests of coagulation, for example,
thromboelastography or bleeding time test, are not
routinely done.
7- Risks and benefits must be assessed and the decision to
place neuraxial anesthesia should be individualized.
8- Generally, it is safe to place an epidural catheter in
patients with platelet counts >75,000mm3 and some
authors will place if platelet count >50, 000mm3 (quoted
from ASA guidelines, 2011).
If decision made to place neuraxial anesthesia:
1. Spinal anesthesia may be safer than epidural anesthesia
2. If epidural is used, use a ‘‘soft-tip’’ flexible epidural
catheter.
3. Use a midline approach to the neuraxis.
4. Use lowest dose of local anesthetic to preserve lower
extremity motor function.
5. Periodically examine lower extremity motor strength to
assure degree of block is not greater than anticipated from
the dose of epidural medication
6. Remove epidural catheter after platelet count has corrected.
7. Early decision to assess with MRI if suspect development of
epidural hematoma (quoted from ASA guidelines, 2011).