Obstetric cholestasis - who is really at risk?

A recent systematic review and meta-analysis has such positive implications for a particular group of women that I made it my study of the month in our March 2019 Birth Information Update.

The paper, by Ovadia et al (2019) was published in The Lancet and it is open access. It is about women who are diagnosed with obstetric cholestasis (which is also known as intrahepatic cholestasis of pregnancy).

We have long known that these women have a higher chance of adverse outcomes, including preterm birth and possibly stillbirth (Ovadia et al 2019). However, although it has long been suspected that the outcomes worsen with the severity of the condition, we did not have good evidence about this and about exactly which women had a higher chance of having a problem. As a result, many women with this condition have been advised to have intervention, including early induction of labour, but without good evidence about whether or not this would make a difference.

But a systematic review and meta-analysis by Ovadia et al (2019), which also includes unpublished data from two UK hospitals has now greatly added to our knowledge, and the key finding will make things a lot clearer for women who develop this condition. Here it is:

“The risk of stillbirth is increased in women with intrahepatic cholestasis of pregnancy and singleton pregnancies when serum bile acids concentrations are of 100 μmol/L or more. Because most women with intrahepatic cholestasis of pregnancy have bile acids below this concentration, they can probably be reassured that the risk of stillbirth is similar to that of pregnant women in the general population, provided repeat bile acid testing is done until delivery.” (Ovadia et al 2019).

I have looked after several women with ICP over the years whose serum bile acids were considerably lower than this cut-off point but who were offered early induction of labour because, at the time, we didn’t have better data.

These findings mean that we can now focus on the very small number of women whose babies may genuinely be at greater risk.

And, as with everything, we can still only talk about risks and relative chances, and I’m not suggesting that every woman whose serum bile acid levels are above this will want intervention when they weigh up the pros and cons in relation to their individual circumstances, but this is a great example of a paper which is really going to help us to determine which women and babies may truly benefit from intervention and which will not.

Balance and not knowing

A few years ago, I wrote the following piece about obstetric cholestasis:

There is a real need for balance in maternity care.

Very occasionally, things can go horribly wrong, which means that vigilance is a vital midwifery skill and we can be very grateful for the array of tools, tests, interventions and pharmaceuticals that are occasionally life-saving.

But on the other side of the seesaw, the vast majority of births will – especially if allowed to unfold physiologically and without undue interference of all the kinds described in the last sentence – progress well to a happy, healthy conclusion for all concerned.

If we apply too little vigilance and/or eschew intervention where it is truly warranted, we may end up with high rates of unwarranted intervention, iatrogenic morbidity, unhappy mums, unsettled babies and all manner of unwanted and perhaps sometimes unknown knock-on effects, which can be emotional and social as well as physical.

The concept of balance can also be considered in relation to the knowledge that we use to underpin decision-making and practice, and the enormous difficulty with achieving the balance described above is that this is not an exact science.

In fact, it’s not really a science at all.

It’s an art which involves juggling different kinds of partial knowledge and bits of information which are often taken out of context and then trying to work out how to deal with the huge gaps of what we don’t know.

Some of this knowledge might come from research and then some will come from other sources, such as expert opinion.

Both, and every other kind of knowledge we generate or use, have advantages and disadvantages.

A good example of a situation which requires balance in both of the dimensions described above is that of obstetric cholestasis, also known as intrahepatic cholestasis of pregnancy (ICP).

There is very little research evidence available to underpin recommendations, and so there is a significant reliance on expert opinion as a form of knowledge. I absolutely acknowledge the concerns that exist about this condition, yet I also see an increasing tendency to intervene in the pregnancies of women who may be affected by this without perhaps having as much knowledge as might be ideal. This intervention, as I noted near the beginning of this post, can increase the likelihood of other problems, which then necessitates consideration of which way the seesaw is moving.

I have spent years researching and writing about areas in which practice recommendations have become almost cemented in place without us really having done enough research to know if they are the right recommendations, or to know whether other possibilities exist.

It only takes a few years after such foundations are cemented before the idea of carrying out additional research (which, in the case of the kind of trial that is deemed necessary in some circles to provide adequate evidence, necessitates removing the now-accepted intervention from those in the control group) is deemed unethical.

There is always a danger that we create guidelines without engaging clear thinking.

So often, I end up thinking that this all comes down to humility.

Within a society that puts a high value on expertise, it is very difficult for professionals in any field to admit that they don’t know something, and yet, if we were all truthful, ‘we don’t know’ would be the most commonly uttered phrase in maternity care encounters.

This latest research just illustrates that further.