What do you do when you can't find the problem?
It is the moment in a viva where your blood runs cold. You have looked at the films once, if not twice or three times, and nothing is popping out at you. You can't find an abnormality, but you know one is there - otherwise the case wouldn't be in the exam.
This problem has been time and time again implicated in derailing the performance of otherwise good candidates, where they might not just drop that case but the whole viva. I got a case like this in my paediatrics exam and my breast exam, and I was very lucky to pull out of it relatively unscathed.
The first thing to do if you don't see the finding is to not panic (which is easier said than done). You can take a breath, close your eyes for a moment or sit back for a different perspective. Try something to snap you out of the period of uncertainty and look at the film with fresh eyes.
In my breast viva, the history told me there was a lump in the right breast. I knew it was there, but for the life of me I just couldn't see it. I was furrowing my brow and checking the axilla and the "Milky Way" and I was coming up empty handed. It was my first case and I was starting to worry that it was all about to fall apart. So I looked at the floor, and took a breath and sat back a little from the film. I have a terrible habit of getting my nose right up against the film so had practiced this technique in the past when I was getting lost in the fine detail. When I sat back, the abnormality became so obvious that I almost started laughing - the breast was almost totally replaced by a lipoma. The abnormality was so large and so obvious in retrospect but I just couldn't see it. Once I found it, I closed the case quickly and kept going.
Chest vivas are a common setting to be faced with a case with an abnormality that you just can't see. I have at least two cases in the bags which I show candidates that the abnormality is unilateral hilar enlargement and the cancer is in the apical segment of the lower lobe. It may be a subtle apical mass, an opacity in the trachea or a supraclavicular soft tissue density. I got a CXR in my paediatrics viva with a finding behind the hilum which I struggled to find. After suggesting the hilum perhaps wasn't quite right and I would review a lateral if available, to my surprise (and immense relief) it came up.
So what can you do to move past it? Number one, revisit the history. Think about the history again as it may give you a clue of what review areas to check again. If the patient has a hoarse voice look for a mediastinal mass which could be impinging the recurrent laryngeal nerve. Cough? Check the lungs, trachea and hila. Trauma? Check the bones.
Number two, try and earn another view. Even if you find something subtle and you aren't sure, you might be able to earn a lateral radiograph where the abnormality is more conspicuous. You could say "The right hilum appears slightly more prominent than the left. I would review a lateral projection to assess this further" - pause - and wait to see if something comes up. You might have picked the salient abnormality, and it's subtlety was the crux of the case. Remember that you will (hopefully) have seen thousands of x-rays by the time you get to the viva and you will have well earned the right to trust you gut.
Number three, check your review areas again.
If you still have no idea what the finding is, the best thing is to wrap up safely. You don't want this single case eating up too much of your precious viva time when there are more films to see. Consider the history. Suggest a safe option "although I don't appreciate a cause for the patient's persistent cough on this film, a high resolution CT chest could be performed for further assessment if there was significant clinical concern'.