Increased AFI (amniotic fluid index)

Question: I went for a ultrascan and my AFI was measured as 22.1 and the reports say its Polyhydramnios. What should be the normal AFI at this week. Please clarify. K (India)

Answer: Unfortunately you forgot to say how many weeks gestation you are. It is therefore not possible for me to give you a specific answer. I will of course be happy to answer that if you can give that information. Alternatively, have a look at the chart of Amniotic Fluid Index (AFI) below. This shows the normal range of fluid volume by gestation from the lower border of normal (5th centile), through the ‘mean’ up to the upper border of normal. You can then locate what your normal should be at the gestation that you are. Word of caution: Since charts for fluid volume vary slightly from population to population, the chart your doctors are using may be slightly different from this one. However, differences tend to be minor. Also note the chart values below are in mm so you need to multiply your measurements by 10.

Treating Deep Vein Thrombosis in pregnancy

Question: My daughter is 12 weeks pregnant. After 4 visits to her GP in the past week with of severe pain, redness and swelling in her thigh,(the thigh is now black). She has now been diagnosed with a DVT. She had a DVT after her last caesarean delivery and was diagnosed with congenital thrombophilia. She is now in hospital in chronic pain and is only being given Paracetamol as pain relief. What else can she be given? What are the risks of ulceration? H. (Spain)

Answer: Are you sure you have the full story here? Sorry to have to question you but it is clearly inconceivable that anybody pregnant, with known thrombophilia and a case of on-going DVT will not be on full-blown anticoagulation. It simply does not make sense to me. For one thing, it is standard practise to put any woman with known congenital thrombophilia on prophylatic (preventative) heparin, usually given as a daily injection as soon as pregnancy is confirmed. If, despite that, the woman goes on to develop DVT, she is then switched onto a much higher therapeutic dose of the same injection. There are various types of these low-molecular weight heparins including Clexane (Enoxaparin), Fragmin (Dalteparin), Innohep (Tinzaparin) etc. They are all similarly effective. I really cannot understand, if the picture is as you put it, why she is not being given this. Untreated DVT in pregnancy is dangerous and I would want to think that everything is being done to deal with this as aggressively as the situation demands. Ulceration would be the least of my concerns.

Interpreting a CTG trace

Question: Could you please explain to me how to read a ctg recording at a glance. Thank you. P.H. (UK)

Answer: I take it, from your question, that you are not a professional; that’s a midwife or doctor. I have to confess that I am a little bit wary of trying to tackle this if you are completely ignorant of the underlying principles. While, on the surface of it, it may appear plausible, this falls squarely into that realm of where ‘a little knowledge may be dangerous’. There is really a lot to a CTG.

Working on the assumption that you will not be tempted to use this to challenge the experts, let me give an example with a CTG trace below:

A normal fetal heart rate ranges from 110 to 160 beats per minute (bpm). If you look at the trace of the fetal heart which is in the area highlighted with lime-green, you will see the heart rate ranged from 140 -160bpm which is normal.

The lower trace marked ‘toco’ records the strength, duration and frequency of the uterine contractions. With each little box representing 10 seconds, you can get all this information from that trace. You can also see how the baby is reacting to the contraction. Sometimes at the peak of contractions the baby’s heart rate may drop (in this case it wasn’t). You will then need to assess how deep the heart rate drop is and, crucially, how long it takes to recover back to its baseline. Delayed recovery is not a good sign.

Sometimes you can notice the baby’s heart rate dropping without any apparent provocation, so-called variable decelerations. That will also need close observation and sometimes investigation for possible fetal compromise.

The fetal heart rate also needs to be changing (within normal range) as seen in the trace above. This is called baseline variability. If the heart rate trace is very flat and stays so for a prolonged period, that may also need investigating.

This is really just a snapshot of the various things one looks at on a CTG trace. Everything needs to be taken in context before jumping to any conclusion. I hope this helps a little.