02/09/2025
Why Those YES/NO Questions Really Matter Underwater
We are all accustomed to the familiar dive medical form.�This sheet of paper, sitting between us and our relaxing dive, can seem routine and appear like a trivial formality. However, behind those simple YES/NO questions lies a deeper purpose. As we prepare to enter the water, the questions may seem dry, but answering them accurately is crucial for your safety.
Some questions carry obvious importance, such as those asking about problems with the lungs, heart, blood, or recent surgery within the last 12 months. Others, like questions about headaches, asthma, or recent diarrhoea, may seem minor. With a desire to get the paperwork over with and hop in the water, it might feel tempting to quickly answer “no,” assuming these issues won’t affect your dive. However, even those seemingly trivial questions are grounded in important science. Answering untruthfully can increase your risk underwater in ways you might not realise. Taking the time to answer honestly helps ensure a safe and enjoyable dive experience.
Let's take a deeper look into some of the more ‘unimportant’ sounding questions and see why they are included in the medical form.
Headaches
It might seem strange to ask about headaches, but frequent or severe ones can sometimes signal underlying issues, such as a Patent Foramen Ovale (PFO). A PFO is a small hole in the heart that usually closes over at birth. Normally, the lungs filter out small clots and bubbles from the blood, but with a PFO, these can bypass the lungs and go straight to the brain, where they may irritate or briefly block small blood vessels and trigger a migraine. It is estimated that 1 in 4 of the population has a PFO! However, the size of the PFO can vary greatly, some being incredibly small.�Divers with a PFO are more prone to “undeserved” decompression sickness because nitrogen bubbles sneak through the heart.
⚠️ Important to note:
* Not everyone with a PFO has migraines, and not everyone with migraines has a PFO.
* But studies suggest migraine with aura is more common in people with a PFO.
Diarrhoea
Recent diarrhoea might feel like just a minor stomach bug, but it can
severely dehydrate you and diving while dehydrated is risky. Dehydration thickens the blood, affecting how it moves throughout the body and how quickly gases move in and out of tissues. This can make decompression sickness more likely. Dehydration also makes people feel weak and dizzy, which greatly increases poor decision-making underwater. That’s why dive professionals want to know if you’ve had it recently – to make sure you’re strong and hydrated before the dive.
Asthma
Asthma is one of the most important conditions to disclose, even if you have mild asthma. Cold, dry compressed air can trigger an attack underwater, which could be fatal. Asthma also narrows the airways, potentially trapping gas in the lungs. On ascent, this trapped gas expands, raising the risk of lung overexpansion injuries and barotrauma.
The Bigger Picture
Dive medical forms aren’t about excluding people; they’re about managing risks. Every question is there for a reason and every question deserves a truthful answer.�In many cases, people with these conditions can dive safely with medical clearance and proper management. What matters most is honesty. By answering truthfully, you give yourself and your dive team the best chance of having a safe and enjoyable dive.