Dr Ian Sibley-Calder has been a GP since 1988, is a medical referee for the UK Sports Diving Committee and is involved with hyperbaric medicine and commercial diving activities. He is a BSAC Advanced Diver and Club Instructor.
Is it possible for women to dive when they are pregnant Will it harm the child, or the woman

The simple answer is that you should not knowingly dive if you are pregnant. There have been many cases of women diving in the early stages while unaware that they are pregnant, and they have continued with no apparent problems, although it is thought that the miscarriage rate may be higher.
There are two people involved with diving when pregnant: the mother and the foetus. The mother has huge changes affecting her body, ranging from hormonal to physical. We do not know if these changes will cause problems in diving or whether there is any alteration to the risk of decompression illness.
The foetus is more worrying. The placenta has an extremely good blood supply and work on sheep foetuses has shown that bubbles do cross the placenta and could potentially lead to a foetal DCI.
Opponents have countered this by using the argument that as the blood supply is so good, the bubbles will offgas easily, so the risk is lower. There has also been collated data to suggest that there is an increased risk of premature birth and birth defects.
Essentially we do not know, and we never truly will. No one is going to do studies on human pregnant women, for good reasons.
This is a sport and is not essential. So as soon as you know you are pregnant, or ideally if you are going to become pregnant, stop diving.
On returning to diving post-pregnancy, once the body has returned to normal and you are back to usual activities, I see no reason why you cannot dive - probably after the post-natal examination at six weeks.

Gut reactions
I was diagnosed with Chrons colitis nine years ago and also have a duodenal ulcer (the two go hand in hand). Ive had no problems in the past with diving. I go to the hospital once a year for a check-up and my consultant said I should have no problem but my diving officer said that I should ask a medical referee. My medication is: 300mg Asacol and 30mg Zoton.

Chrons is one of the inflammatory bowel disorders that can cause inflammation and ulcers anywhere in the bowel from the mouth to the anus. Symptoms can include indigestion, severe unpredictable diarrhoea and general symptoms such as lethargy due to anaemia.
There can be many complications depending on the severity of the disease process, including ulcers, narrowing of the gut, bleeding, infection and perforation.
It is treated usually by medication including groups of drugs called immunosuppressants that reduce the bodys immune defence and steroids. In severe cases a person might require surgery to excise part of the affected bowel.
Its impossible to say if a person is fit to dive without knowing in detail his or her disease history, any complications and what medication is being used.
Most with mild disease will be fit to dive, though often having to be very aware of the urgent need for a toilet!
Others with severe disease will not be fit because of the risk of gut-narrowing and perforation, and because the gut gas expands during ascent. In general, people with Chrons should be assessed by a diving doctor on an annual basis, or if any complications occur.

chilles heel and finstrokes
Last May I suffered a rupture of my Achilles tendon which required surgery to rejoin the tendon and a number of months of physiotherapy to get full use again. I now have full movement and am able to run without any reaction. Beyond the obvious strain on my leg, is there any increased risk when I start diving again In particular, is there any impact on decompression rates for the area affected

The Achilles should be fine if you have managed to get running again and your doctors regard its strength as back to normal. I dont think there will be any risk regarding recompression.
The issue does raise the interesting notion of fin design, however. In my experience fins have differing stresses on different parts of the leg.
It may well be worth trying different designs out in a pool in an effort to reduce the stress on your Achilles. I wonder if fins with short rapid movements may be better than ones that require long, forceful strokes

Heart condition
I have been diagnosed with a mild case of pulmonary stenosis. It does not affect my everyday life and the only precaution I have to take is to be covered by antibiotics if I have any dental work, including cleaning, or if I were to have surgery. Would this prevent me from getting my PADI Open Water certificate

Right valvular disease in general is not as worrying as left-sided, as long as it is very mild.
The most worrying valves in which to have stenosis are the aortic and mitral, both of which can be associated with sudden loss of consciousness and are therefore incompatible with diving.
Saying that, right heart disease can still give rise to right heart failure and venous congestion.
You are probably OK to dive, but you need to be assessed by a cardiologist interested in diving and probably need to have regular annual follow-ups.

Raised blood pressure
I have been diagnosed with high blood pressure by my GP and am undergoing some blood tests. I am 37 and very active in sport. Considering that I have only one kidney, what is the best type of medication for me I dont want to give up diving and my GP is not very clued up on its effects on the body.

Your GP is going to look for any reasons why your blood pressure may be increasing. Lots of people can cope well with only one kidney (though you do not say why you have only one) but as kidney disease can raise blood pressure, this may need to be looked into further.
Assuming that there are no obvious reasons for the increase in blood pressure and that all your tests come back as normal, the choice of blood-pressure medication is wide.
I generally avoid beta blockers and diving because of exercise limitations and possible lung effects. My favourite, and recently endorsed by trial data, are ACE inhibitors.
These are tolerated well and have minimal side effects. Other choices would be vasodilators, diuretics (water tablets - not so good in a drysuit) and alpha blockers.

Epileptic fits and diving
I have eight years diving experience and have done 154 dives. I have recently suffered some tonic-clonic seizures. I had two in mid-August at night and seven a month later, again at night. An MRI scan of the brain was clear and I am due an EEG soon. I take 200mg of Carbamazepine twice a day and have been advised not to drive for a year and also not to dive. I would like to have more information about diving and epilepsy.

Active epilepsy and diving are not compatible. There are two risks. The first is of a seizure under water, which would almost certainly mean death through water inhalation during the fit.
The second regards the medication. All epilepsy medication affects the brain and its activity and often has side-effects, including drowsiness and dizziness. These would almost certainly be altered by pressure, with unknown consequences.
The suggested requirements for an epileptic to be permitted to dive are five years free from fits and off medication. Where the fits were exclusively nocturnal, this can be reduced to three years. This time delay reduces the risk of a future fit to that of the average population.

Broken nose repairs
I am having corrective surgery to put the bone across the bridge of my nose back to its original position after it was broken. The break is not big but I will have it in a cast for seven days. How long should I leave it before diving again The consultant seems to think I could resume almost immediately.

It would seem that in your case the surgery is going to be minor and not affecting the sinuses or entailing major disruption to the air passages. My advice would be to return to diving only once you have full clear airways.
Remember that most bones take four to six weeks to settle down after breaking (at least) and if there is a lot of swelling this will be uncomfortable with mask-squeeze, nose-pinching and so on. Use common sense.
For those requiring more major surgery, if it is likely to affect the sinuses or lead to sinus congestion there is a real risk of sinus squeeze or reverse block. Be cautious on return and dive only when fully recovered.