My Obstetric Recipe

Last updated on Mar 23, 2023

Following on from the positive feedback for our previous recipes post, we've decided to follow up with an obstetric one.

Remember - there are many ways of achieving a good anaesthetic, and this is just our way of doing it. Please feel free to fire away with any feedback or suggestions, we'd be delighted to hear from you!

Epidural for labour analgesia

In our trust we have pre-made bags of 0.1% levobupivacaine and 2mcg/ml Fentanyl, which is referred to as 'low-dose bag mix'

Once I'm happy the epidural catheter is in the epidural space, I will give 5mls of bag mix manually with a syringe, prior to fixing and dressing the catheter in place

This has two advantages:

It starts to work quicker than if I fix and dress the catheter, prime the giving set and attach the pump, then deliver a bolus using the pump
It is a fairly safe dose, even if the catheter somehow magically migrates into the intrathecal space

By the time I've then got the catheter fixed firmly in place and the pump set up and ready to go, I can check the woman hasn't got a high spinal block, and can give a further 10-15mls through the pump without worrying too much.

Epidural top up for Caesarean section

If the woman says her epidural has been working well throughout labour, and I'm happy to use it for a top up for a section, then three drugs go down the epidural catheter (once I've aspirated to check it's not gone into the intrathecal space).

18mls 0.75% Ropivacaine
2mls (100mcg) Fentanyl
3mg diamorphine

Draw the ropivacaine and fentanyl up into a 20ml syringe, and give 10ml at a time, checking the block doesn't go too high too quickly after the first dose.

You can give further top ups a couple of ml at a time with ropivacaine (don't exceed 3mg/kg) if the epidural is working but not quite high enough.

The diamorphine is given at the end of the case, for ongoing analgesia once the fentanyl wears off.

Spinal drugs

I pretty much always inject a total volume of 2.8ml for caesarean sections, unless the woman is exceptionally tall or short (adjust by 0.2ml or so in either direction).

2.4ml 0.5% heavy marcain (bupivacaine)
0.4ml of opioid

If there is diamorphine available, I will give 400mcg of diamorphine, if not, then I'll give 0.3ml (or 15mcg) of fentanyl and 0.1mg of preservative-free morphine.

My routine is to plumb the fluids and phenylephrine (0.1mg/ml) infusion into the cannula and start the phenyl at around 3ml/hr to prime the cannula and get a little bit into the patient, while I set up for the spinal.

I don't do this if they're already significantly hypertensive, such as in pre-eclampsia.

Then once the spinal is in, I immediately increase the rate to 30ml/hr before the woman then lies down (with left lateral tilt).

Generally I find this method prevents that awful post-spinal hypotension where the woman goes horrifically pale and feels very sick, but the key as always is to keep monitoring and adjusting as needed.

Saddle block for suturing

If a woman needs to go to theatre for repear of either episiotomy or perineal tear, then a saddle block is all you need.

I generally go for 1ml 0.5% heavy bupivacaine with a little fentanyl (20mcg) to speed up the onset of the block.

Ideally the woman would be sat for the spinal to encourage the hyperbaric solution to sink but they may be in too much pain to sit upright, in which case a larger dose might be needed in the lateral position with some head up tilt.

Post operative prescriptions

Remember that you're not just treating pain postoperatively, there's also nausea, vomiting, constipation and itching to think about. In general I prescribe:

Paracetamol regularly 1g QDS (assuming bodyweight >50kg)
Ibuprofen regularly 400mg TDS with food (assuming no contraindications)
Dihydrocodeine 30mg TDS PRN
Oramorph 10-20mg 2-4hourly PRN
Lactulose 15mls BD PRN
Ondansetron 4-8mg TDS PRN
Cyclizine 50mg TDS PRN

Note that codeine has been found to transfer through breast milk, but tramadol and dihydrocodeine are considered safe. Nevertheless - monitoring of the baby for evidence of sedation or respiratory depression is essential.