This fairly rare complication has received a level of attention from the CICM examiners which is out of proportion to its prevalence in clinical practice. It would be rare to see this unless one works in a centre where many bone marrow transplants are performed. In spite of its exotic nature, VOD has appeared in multiple past papers:
The college presents their exam candidates with a scenario of a bone marrow transplant recipient whose LFTs have suddenly become deranged. In addition to this, some pressure variables are listed (right atrial pressure and portal venous pressure). This is weird, because pressure measurements are not diagnostic of VOD. There are the Seattle criteria and there are the very similar Baltimore criteria, neither of which actually mention any pressures at all - they demand hepatomegaly, ascites and raised bilirubin. The pressure values are given in the SAQ so that the candidates can confidently exclude cardiac congestive hepatopathy.
One pressure variable which might be of use is the hepatic venous pressure gradient, which would require a WHVP (wedged hepatic venous pressure). You never end up measuring this variable unless you are performing a transjugular venous liver biopsy. This gradient is the difference between the wedged hepatic venous pressure and free (unwedged) hepatic venous pressure. The wedged pressure approximates the portal venous pressure, in a similar sense as PAWP approximates LA pressure. If the gradient is greater than 10mmHg (i.e. the free hepatic venous pressure is 10mmHg lower than the portal pressure) then there is obviously some sort of obstruction to flow, which is the veno-occlusive disease.
Diagnosis does not require ultrasound, but it is usually ordered in this context. The BCSH/BSBMT guidelines (2013) concluded that "the main role of ultrasound is to exclude the presence of other diagnoses" because the ultrasound findings which are usually associated with VOD are insufficiently sensitive and specific. In any case, here they are: