Viva technique

Last revised by Daniel J Bell on 3 Apr 2023

Viva technique is hugely important when sitting oral examinations. You must remember that the examiners may well have been examining for several days and for hours at a time. They will have shown their films many times and will know them backwards! Moreover, their films will be beloved, so do not criticize them, e.g. suggesting poor quality.

Tired examiners need to see a confident candidate, even if you do not feel it. They want to interact with you, so do not sit bolt upright looking at the viewing box or computer screen - you need to appear professional and be able to interact with them without freaking them out. Eye contact may appear odd in the professional exam, but do your best to turn and make eye contact when you can - especially when you have finished describing a film.

When the film goes up, you do not have long before you need to start talking. You will likely be in one of two positions:

  1. there is an obvious abnormality

  2. the film looks normal - do not panic, there are some tools you can use to buy time

If you are dealing with a plain film and you see the abnormality, do not waste time by starting to talk about the fact that it is a frontal radiograph of an adult patient - the examiner has shown you a film with an abnormality on it and has probably heard these words hundreds of times - he wants to know that you have seen the abnormality. So, let him know: "there is bilateral basal opacification with an interstitial distribution...".

If the film is not a plain film then it is worthwhile describing what you have been shown - this is especially true in the setting of hard copy:

  • selected axial images from an unenhanced CT of the head

  • selected images from an MRI spine - sagittal T1 and T2 and limited axial T2 sequences through the L2 disc

  • sagittal T1, axial T2, FLAIR, DWI and ADC sequences

This allows you to get your brain in the right place and not make silly errors by describing an enhancing mass on a non-contrast CT or a lesion with high T1 signal on a FLAIR sequence. "That surely couldn't happen" - unfortunately, it does in the stress of the exam. 

It is unlikely that the examiner will spend valuable time showing you a normal film - exceedingly unlikely! One should never say never in medicine, but you get the idea.

So, if the film looks normal, it is more than likely that either you have missed something or it is a difficult film - so do not panic.

You cannot just sit there in silence - you need to explain to the examiners that you haven't seen anything obvious but that you are a good radiologist and you are going to review the film; this is the time to go back to basics.

Buy some time - now you can start with some basic patter, e.g. "This is a frontal chest radiograph of an adult male patient" 

  • it is probably worth steering clear of AP/PA in favor of "frontal" - if it's important, it will come up later in a question

  • know your projections, e.g. don't make the mistake of calling a DP foot radiograph an AP one

  • comment on skeletal maturity (i.e. mature or immature) when discussing skeletal films: the list of differentials will be completely different for the two sets of the patients and it shows that you are thinking

This may have given you enough time to have a slightly closer look at the film and see the abnormality. If not, then good practice comes to your rescue: "On initial inspection, I haven't seen an abnormality and it is my normal practice to look at my review areas". Your review areas will be different depending on the film in front of you. As you look round these review areas, you will more than likely find the abnormality.

However, if disaster strikes and even after looking at the review areas, you still have not seen the abnormality, it is best to stick with honesty and declare it to the examiner rather that sitting in silence, tutting and sighing: "after looking at my review areas I cannot take the film further without further information - discussion with the clinical team would be helpful to guide further investigation".

Where an obvious abnormality presents itself, let the examiners know that you have seen it. There is no point keeping that information to yourself and looking at the rest of the study. Mention it and then get ready to describe it and consider its implications.

What you should not do is describe the abnormality and then wander off to talk about something else. The examiner will be asking themselves whether you think the abnormality you just mentioned is important. If it's the only thing on the film, all the time you spend checking (and stressing) about the rest of the film, you will hemorrhage points.

There is expansion of the proximal femur with coarsening of the trabeculae and the bone is dense. It's Paget's. They know it's Paget's and you know it is... play the game though:

  • describe it:

    • "The proximal left femur is expanded, dense and the trabeculae are coarse. The joint is not involved and the pelvis appears normal."

  • consider the diagnosis:

    • "Features are consistent with Paget's disease of bone."

  • contextualise:

    • "While Paget's disease may be monostotic, other bones may be involved and plain films of other bones may show similar changes."

    • "While the bones in Paget's disease are thickened, they are not as strong as normal bone and there is an increased risk of pathological fracture."

This time, it's a complete femur radiograph from the other side. The distal portion of the bone is grossly abnormal and there is a fracture - now it's time to shine:

  • look further:

    • "The distal right femur is grossly abnormal. It is expanded with a lytic component, periosteal reaction and a soft tissue mass. Additionally, an oblique fracture extends through the distal femur but does not extend into the joint."

    • "These are features of malignant degeneration of Paget's disease with pathological fracture. The most common malignant transformation occurs with sarcomatous degeneration that occurs almost exclusively in over 50 year olds and twice as commonly in men. It is a relatively rare complication of Paget's disease, occurring in about 0.1-1% of cases."

Wow! Do not wait for them to drag the information out of you - give it to them on a plate. Remember that this type of delivery doesn't come without practice, so give yourself a chance and practice some exam set-pieces.

At points through the viva, you will want to get more information from the examiner; either in the form of clinical information, or another study. Do not ask them for it!  To get more information, you need to earn it.

So, in the patient with bihilar lymphadenopathy, you could ask "are there any respiratory symptoms" or "does the patient have a leg rash", but is wholeheartedly more impressive to say:

"The differential here includes sarcoidosis, lymphoma and tuberculosis. In a patient with leg rash and respiratory symptoms that are non-infective, the most likely differential would be sarcoidosis and a high resolution CT chest would be useful to assess the stage of disease [get ready for the question on staging of the disease]. However, if the patient had peripheral lymphadenopathy or B symptoms, lymphoma should be considered.  TB would be more likely in patients with exposure or those who are immunocompromised."

You have got through the differential in a logical manner with lots of relevant information and have seeded a couple of questions such as the staging of sarcoidosis, a question of lymphoma and possibly on B symptoms. Be careful not to tie yourself up with questions you cannot answer!

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