A reverse block is a pressure-related problem that can occur during ascent when expanding gas cannot escape from an air space, commonly the middle ear or sinuses. It may cause pain, pressure, or difficulty continuing the ascent. It is different from difficulty equalizing during descent, and it should not be ignored.
Why can it happen?
Gas expands as ambient pressure decreases during ascent. Congestion, inflammation, or other blockage can interfere with the normal release of gas from an air space. The cause and severity vary, so an article cannot diagnose an individual case.
What should a diver do?
If pain or pressure develops during ascent, stop the ascent and follow the emergency procedures taught in your course. Do not force your way upward through significant pain or make a rapid, uncontrolled movement. Communicate with your buddy and follow training and professional guidance for managing the situation. Seek medical evaluation after the dive if symptoms persist or are significant.
How can risk be reduced?
- Do not dive when significantly congested or unable to equalize comfortably.
- Equalize gently and early during descent, and never force it.
- Follow your training for controlled ascents and pressure-related problems.
- Seek advice from a diving-medicine professional if ear or sinus issues recur.
When to get medical help
Significant pain, hearing loss, vertigo, bleeding, or persistent symptoms after a dive warrant prompt medical assessment. Tell the clinician that you have been diving and explain when symptoms began.
Bottom line
A suspected reverse block requires a controlled response and should not be pushed through. Follow training, communicate with your buddy, and seek professional assessment for concerning symptoms.
Understanding a reverse block in scuba diving
A reverse block occurs when gas becomes trapped in an air space and cannot escape easily during ascent as surrounding pressure decreases. It may cause pain or pressure in the ears or sinuses and can be associated with congestion, inflammation, or difficulty equalising normally. The term is not a reason to diagnose yourself underwater; symptoms should be taken seriously and managed according to training.
Reducing the likelihood
Avoid diving with congestion or illness that affects equalisation, and do not use medication simply to force a dive to go ahead without appropriate medical advice. Descend and ascend in a controlled way, equalise gently, and stop if discomfort develops. Never force equalisation or ignore increasing pain in order to stay with a group.
What to do if discomfort occurs
Signal your buddy and follow your training to manage the ascent safely. The appropriate response depends on the situation, so do not rely on a generic internet instruction for a real emergency. After surfacing, seek medical assessment if pain, hearing changes, dizziness, or sinus symptoms persist. A clinician familiar with diving medicine can advise when it is safe to return to diving.