Cinderella and the Clexane

The OAA meeting was televised live into Melbourne The atmosphere was saved several tons of avgas carbon dioxide and we sat down like you would for an evening of Wimbledon or the test at Lords. The audio was very good and the powerpoint slides came up well, although the vision of the speakers was a bit grainy.

Rachel Collis presented the popular topic of anticoagulants and obstetric anaesthesia. The basis of her case is that anticoagulants and neuraxial techniques do not mix. She referred to the experience in the USA where there was a spate of haematoma in elderly females who received epidurals soon after prophylactic LMWH for orthopaedic surgery and was dismayed by a survey (published by Wee in IJOA) that revealed that a sizeable number would perform a block in parturients who had received LMWH in the previous few hours. She reinforced the dictum of avoiding neuraxials 12 hours after a prophylactic dose and 24 hours after a therapeutic dose of LMWH. And a dictum it was; it came along with a reference to the lawyers that had clearly terrified the audience in an earlier session.

I think it is regrettable that we get stuck on a fixed interval of time, or a fixed level of a laboratory result. It is a nonsense to state that a block is unsafe one minute (before 12 hours) and unsafe the next (after 12 hours). Taking away the option of regional anaesthesia can be an enormous imposition on the parturient, her supports and her carers. It should be considered in the clinical context. Locally, we have inadvertently performed several blocks (in obstetric cases) in the few hours after enoxaparin with no harm. I suspect the young female spinal canal is compliant and leaky and the risk of compressive haematoma is quite small. The results of the Swedish survey similarly conclude that it is postmenopausal women with their osteoporosis and spinal stenosis who are the ones at risk; we shouldn’t extrapolate their risk onto younger patients.

When considering the option of a neuraxial block one should consider the time of the previous enoxaparin( noting that the anti-Xa effect peaks at about 3 hours then reduces) , the airway (obesity and comorbidities may have been a contributing cause to the reason they were taking the LMWH) and the current situation. For instance, if in early labour, we could wait and avoid augmentation a few more hours (and not necessarily until the clock passes over 12 hours) before doing an epidural. But if there is severe fetal and maternal distress in active labour at 2 a.m. a spinal may be justifiable in a patient with a worrying airway. Of course the block should be followed closely to ensure it regresses over the following 3 hours. In the rare event a haematoma did occur we should be in a position to diagnose, image and treat it. But in the otherwise uncomplicated patient with an easy airway and a likelihood of rapid progression and normal delivery, not doing a neuraxial is likely to be the prudent move.

We do not have to be like Cinderella watching for the clock to go to twelve. We should be able to make tough decisions in difficult circumstances. If we treat on lawyers’ admonitions rather than medical nouse, it’s game over.