​The above CTG shows late decelerations, suggestive of foetal hypoxia (in this case a cord prolapse), and indicates a need for immediate delivery of the baby.
Below is a crash course on cardiotocography (yes, that’s what it stands for). If you want a more in-depth (but still user friendly) review, check out Geeky Medics.com. Here’s the big headlines.
1.The CTG measures 2 things:
a.Foetal heart rate (above)
b.Uterine tone (below).
c.Each big square usually represents one minute.
2.The foetal heart rate will exhibit some variability around the normal FHR of 110-160/min. Normal variability is between 5 and 25 beats per minute.
3.A foetal heart rate of <100 is defined as bradycardia and is cause for concern.
4.Accelerations of heart rate in line with uterine contractions occur in a healthy foetus.
5.Early decelerations of heart rate (basically during uterine contraction) are also more likely than not to be physiologic.
a.Note that there is some subtlety to this, meaning it’s probably not an ACEM fellowship exam topic.
6.Late decelerations begin (as above) with the apex of uterine contraction. They occur, because at maximum uterine pressure perfusion insufficiency is maximal. In other words, late decelerations indicate foetal hypoxia, and are an obstetric emergency.
7.If you ever see a sinusoidal CTG (as in a proper sine wave) it is a critical emergency and indicates severe foetal hypoxia, anaemia or foeto-maternal haemorrhage.
 
That’s an absolutely “brass tracks” interpretation of a CTG. There is FAR more too it than that in real like (which is why it’s done by obstetricians rather than emergency physicians…)
However, if what is above is what you take into the exam about CTGs, it’s probably enough to pass the question. We are big believers in investing time in high yield topics, rather than very unlikely ones. CTG is an unlikely one, and if you read and remember this, you probably need to read no further.
We plan to make a bit of a FPFF series on “stuff you’ll never see, but just in case…”. If there’s other topics  our readership wants us to take on, let us know by our facebook page.

Stuff you’ll never see….but just in case.
Occasionally the examination throws up stuff we just don’t expect will be present. Part of preparation is both casting a wide net so that it’s unlikely you’ve missed anything important, and also understanding that there is logic and rules to how the examination is played.
Take the following question:
You are called to attend a 38yo P1G0 woman who is 38/40. She has presented to your department with severe rhythmic cramping in the abdomen. A midwife has attended from birth suite and hands you a CTG which is shown below. Describe and interpret the CTG and outline your actions.
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​So, before you think “this is completely ridiculous and would never happen in real or exam life”, there was a CTG question on a recent exam.
Step back for a moment, and ask yourself what you’d do with this. Next week, we’ll get a brief outline of CTGs into the FPFF.
But, if you’ve never seen this before, take a moment and have a think about how you might answer.
Can you use exam smarts….?
Here’s an example of what that might look like.
i.“This is the emergency medicine exam. It’s highly likely that the prop I have been given shows a significant emergency.
a.It might be a normal prop, but this is far less likely
ii.This is not a test routinely reviewed by Emergency Physicians.
a.I won’t be expected to have detailed in depth knowledge of subtleties
b.In other words, the findings should be pretty obvious.
iii.CTGs are done for ? foetal distress. It is therefore highly likely that this is what is shown on the CTG.
iv.Therefore, even knowing nothing about CTGs, with the context of a woman in advanced pregnancy in abdominal pain, I would guess and say that the CTG is most likely to show significant signs of foetal distress.
v.I know that CTGs measure foetal Heart Rate.
vi.Therefore I will answer with the elements of the CTG shows foetal bradycardia and urgent obstetric intervention is needed to deliver the baby.
a.I might not get all the marks, but hopefully I’ll get enough to pass.
b.If I’m wrong, there are no negative marks, so what do I have to lose.”

You might think that’s pretty out there.
It is. And it’s certainly not a way to practice medicine in real life.
But, in preparing for the examination, we are believers in using every strategy available when the occasion calls for it. If knowledge and experience fail, try stepping back and thinking about *why* you are being asked the question, rather than just the content of the question itself.