2007-02-12 00:00 来源:丁香园 作者:British Journal of Haematology
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Anaesthetic management options

The obstetric anaesthetist is often called upon to make a decision regarding the advisability of regional analgesia and anaesthesia in these cases. Several textbooks and articles offer guidance on this subject, and the general trend in recent years has been to lower the 'cut-off point' from a platelet count of 80–100×109/ l (Beilin et al, 1997). In fact, there is no evidence to support this sort of  "all-or-nothing" approach, and every case must therefore be considered on its own merits, with the risk of the procedure (epidural / spinal haematoma) balanced against the bene?ts (pain relief, better blood pressure control, avoidance of general anaesthesia).

When monitoring platelet levels, the trend as well as the absolute value is important, and the mother with a rapidly falling count should be regarded with more suspicion than the one with a low, but stable, platelet level (Greaves & Letsky, 1997). At the same time, the cause of the thrombocytopenia must be taken into account since different pathologies have different effects upon the haemostatic mechanism for a given platelet count. In general, patients with a platelet count of > 80×109/ l in the absence of pre-eclampsia are unlikely to have significantly altered platelet function. Tests of platelet function, such as bleeding time, are operator-dependent and therefore of limited predictive value. Thromboelastography is a promising development in this field, but its place in clinical practice has yet to be determined, and will require further clinical trials (Gorton & Lyons, 1999). Routine coagulation studies are usually indicated in thrombocytopenia in case any other defect should be present. The mother should always be questioned about excessive bruising or bleeding since the presence of these may signify impaired platelet function in borderline cases.

The use of powerful non-steroidal anti-in?ammatory drugs for post-partum or post-operative analgesia should be avoided in women with platelet counts less than 100 ? 109? l because of their anti-platelet activity which may increase the risk of haemorrhage (Level IV Evidence, Grade C Recommendation).

Venous thromboembolism (VTE) is the commonest cause of maternal mortality in the UK and all women with ITP should be considered for thromboprophylaxis if they are undergoing surgical delivery, are immobilized by other medical complications, have a congenital or acquired thrombophilia (especially the antiphospholipid syndrome) or recent venous thrombosis. In each case an individual risk assessment must be made about the desirability and safety of anticoagulant therapy taking into account factors such as age, obesity and personal and family history. Although there are no published data to guide clinical practice, treatment or prophylaxis with standard doses of unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) should be used in women with platelet counts > 50×109/ l (Level IV Evidence, Grade C Recommendation) in whom the risk of haemorrhage is very low. In women regarded at especially high risk of VTE (e.g. antiphospholipid syndrome, antithrombin de?ciency) the balance of risks would probably favour thromboprophylaxis at platelet counts down to 50×109/ l, especially if LMWH with its more favourable ‘therapeutic window’ is used. All at-risk patients should use appropriate graduated compression hosiery and be considered for intermittent mechanical pneumocompression of the calves during surgery (Level IV Evidence, Grade C Recommendation).

♦ The mode of delivery in women with ITP should be decided by primarily obstetric indications. There is no evidence to support the routine use of caesarean section (Grade B)
♦ Platelet counts > 50×109/ l are safe for normal vaginal delivery if coagulation is otherwise normal
♦ Platelet counts > 80×109/ l are safe for spinal ? epidural anaesthesia or caesarean section if coagulation is otherwise normal
♦ Women undergoing operative delivery should be considered for thromboprophylaxis according to their individual clinical risk factors. Standard prophylactic doses of UFH or LMW heparin should be used if the maternal platelet count is > 100×109/ l (Grade C)
♦ Non-steroidal anti-in?ammatory drugs should be avoided for post-partum or post-operative analgesia in women with platelet counts < 100×109/ l (Grade C)
♦ The risk of clinically dangerous thrombocytopenia in the neonate is very low but cannot be predicted by clinical or laboratory parameters in the mother. Attempts to measure the fetal platelet count by cordocentesis or fetal scalp blood sampling are not recommended as they carry more risks than potential clinical benefits (Grade B)
♦ Because of the risk of haemorrhagic complications in the neonate the application of scalp electrodes for monitoring in labour and fetal blood sampling should be avoided. The use of vacuum extraction (ventouse) is contraindicated and complicated instrumental delivery (e.g. rotational forceps) should be avoided if possible (Grade C)
♦ Cord platelet counts should be measured in all neonates of mothers with ITP and those with subnormal levels monitored clinically and with daily counts until after the nadir which usually occurs on d 2–5 after delivery (Grade C)
♦ Treatment of the thrombocytopenic neonate should be reserved for those with clinical evidence of haemorrhage or a platelet count < 20×109/ l when there is usually a prompt response to IVIg (1 g / kg). Life-threatening haemorrhage should be treated with immediate platelet transfusion and IVIg (Grade C).


For patients with ITP in whom heavy menstrual bleeding occurs, symptom control may be achieved using tranexamic acid and ? or oral contraceptives. The Mirena coil is a progestogen-loaded intrauterine contraceptive that induces endometrial atrophy, and is effective in controlling menorrhagia.


The ITP Support Association was formed in 1995 to offer support to those with adult, childhood and maternal ITP. Assisted by its medical advisors the Association publishes a quarterly newsletter and a wealth of reader friendly booklets and factsheets on ITP and its associated concerns, including guidelines for schools, protocol for dentists of affected patients, splenectomy patient’s guide and holiday guidelines. ITP HealthCare cards are supplied for a small fee, giving personal details on a wallet-size laminated card in case of emergency.

Annual national conventions featuring ITP specialists from the UK and USA allow patients to overcome their feelings of isolation by meeting fellow sufferers. The Association has funded research and part funded the National Register of Patients and the ?rst ITP Specialist Nurse. By sending an A5 SAE with 2x 1st class stamps to The ITP Support Association, Synehurste, Kimbolton Road, Bolnhurst, Bedfordshire, MK44 2EW, UK, ITP sufferers ? families can receive a free information pack. There is no membership fee, the ITP Support Association is run by volunteers and relies mainly on voluntary donations to fund its operation. Further information can be found on http://www.itpsupport.org.uk and Where to Get Help patient lea?ets can be ordered free of charge by e-mailing shirley@itpsupport.org.uk.


Although the advice and information contained in these guidelines is believed to be true and accurate at the time of going to press, neither the authors nor the publishers can accept any legal responsibility for any errors or omissions that may have been made.

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