Dr Peter Wilmshurst has been a qualified doctor for over 25 years. He has served on the BSAC Medical Committee since 1977 and also advises the HSE on diving.

I am going abroad to do an open-water course but I will be nine weeks pregnant. Will this have any effects or harm me and the baby in any way

This is a question that comes up frequently. We do not have very good information about the risk of diving during pregnancy, because definitive data could be obtained only by deliberately doing research on a large number of pregnant women. Such a prospective study would be unethical.

Prospective animal research has yielded conflicting results and it is hard to know whether the findings can be extrapolated to humans. We therefore have only anecdotal reports on women who dived during pregnancy, either because they were unaware that they were pregnant or because they decided to dive anyway.

This evidence suggests that decompression illness and its treatment in a recompression chamber might be harmful to the foetus. Even shallow dives can result in pulmonary barotrauma and gas embolism which might require such treatment.

There is also some anecdotal evidence that deep dives (to more than 30m) are associated with an increased risk of foetal abnormalities, and a suggestion that spontaneous abortion might be more common in women who dived during pregnancy, especially if they did more than one dive each day, or dives requiring compulsory stops.

There is no proof that diving in pregnancy is unsafe, but to be certain that the foetus will not be harmed, the advice is not to dive. If you decide to dive anyway, the UK Sport Diving Medical Committee recommends that you minimise your gas loading.

Diving on anti-depressants
My doctor suggested that I take Prozac (fluoxetine) to manage my pre-menstrual tension. Can I dive on it

I am a PADI Advanced Diver, female, 29 years old. I am on Seroxat (paroxetene) for depression. Can I dive

Prozac and Seroxat are newer anti-depressants. There has been insufficient research for us to be sure that they are 100 per cent safe for use by divers, but we think from their modes of action that they should not present any problems if used on shallow air dives, provided that the divers have only mild depressive illness.

Some older anti-depression drugs have effects which might be harmful in divers and represent a bar to diving. We would not be happy for an individual to dive while taking any anti-depressant if he or she had severe depressive illness.
Getting back after a heart attack...
I am an experienced PADI diver but suffered a heart attack eight months ago. I am now fit again. Are there any restrictions on resuming diving

Some diving organisations permit established divers to resume diving after a heart attack (myocardial infarction) provided recovery has been complete, the diver is able to exercise well without angina chest pains or other symptoms, and he or she passes various tests to show that heart function remains good.

Restrictions are imposed on types and depths of dives (no-stop diving only) and buddies (experienced only), if a diving doctor passes you fit to dive.

...and heart surgery
I had a coronary angioplasty last year and wish to know whether it is possible to dive.

Narrowed coronary arteries can cause angina and lead to heart attacks. Coronary angioplasty is used to treat these narrowings. A cardiac catheter, a tube about 2-3mm in diameter, is passed up the aorta to the heart and used to position an even smaller tube across the narrowing. The smaller tube has a tiny balloon on it and this is inflated to very high pressure in the narrowed segment to open it up, which can relieve angina.

Diving is permitted in some circumstances after coronary angioplasty, but special requirements and restrictions apply. You will need to speak to a medical referee to see whether you satisfy those requirements.

After-effects of rheumatic fever
My wife had rheumatic fever as a child. She has had no heart problems in the 35 years since then. Will this childhood condition put her at risk when diving

Rheumatic fever follows an infection with certain types of bacteria which set off an immune reaction in the body. Because the bacteria have certain immunological similarities to the heart, inflammation of the heart occurs in some people.

This can result in scarring of heart tissue, particularly the valves. If these are badly affected, diving can pose a risk. However, most people who have rheumatic fever do not get significant heart valve damage, and for them diving is no problem.

Pulmonary embolism and warfarin
I recently suffered a deep vein thrombosis with the complication of pulmonary embolism. Some doctors say that this does not preclude me from diving (I am a commercial diver and a keen free-diver) but that the warfarin therapy I take does.

A deep vein thrombosis (DVT) is when clots occur in veins, usually in the legs. This interferes with the way blood drains from the leg, so it is usually swollen and painful.

Sometimes a bit of the clot breaks off and travels back through the right side of the heart to the lungs. The effects of this pulmonary embolism depend on the size of clot, but include chest pain, breathlessness and collapse.
Rarely, the clot is so large that the right side of the heart is strained because the pulmonary embolus blocks so many of the pulmonary arteries.

DVT and pulmonary embolism are treated with warfarin and occasionally other drugs. Some individuals need to stay on warfarin for months, others for life, depending on whether the cause of the clotting has been corrected. The cause will affect whether a diver can resume diving after a DVT and pulmonary embolism, and a diving medical specialist should be consulted. For warfarin, see below...
I am about to start taking warfarin. Is it still safe to dive

Warfarin is a drug used to treat patients at increased risk of blood-clotting, including those at risk of stroke, those with certain types of heart disease and those who have had DVT and pulmonary embolism.

The question is not just whether use of warfarin is safe in a diver but also why it is required.

Warfarin itself is a risk because it increases the chances of bleeding if one suffers problems on a dive.

For example, barotrauma in an ear or sinus can cause bleeding, and the effect will be worse if the diver is on warfarin - similarly bleeding into the spinal cord, which can be a feature of spinal decompression sickness. So there is no simple answer to this question.

Amateur divers might be allowed to dive in some circumstances, if the reason for the diver being on warfarin does not itself pose a risk, but restrictions are likely to be imposed. Commercial divers are not allowed to dive on warfarin.

Unsafe on methadone
Is it possible to dive while on methadone treatment

Methadone is a heroin substitute in individuals with addiction. It is not safe to dive if you need methadone.