Post surgery hidden death

I have a question about an issue I faced a moment ago. I have a patient who has PAD. He has had surgery but keeps having heart failure. I have run every test for every diagnosis on the diagnosis tab but there is still 1 symptom remaining. The symptom eventually killed the patient and after an autopsy it turned out I needed to perform an Echo to diagnose Cardiac tamponade. As Echo was NOT used for any of the symptoms that are associated with PAD, how am I meant to know to run that test? (I'm currently on Specialist Difficulty to obtain my 60 treatments whist simultaneously sitting on 8 of 10 days with untreated patients). So, I'm running every test the game tells me to to uncover symptoms to treat but doesn't give me any clue that the remaining symptom is outside of the set symptoms for the condition the patient has, causing the patient to die from repeated crashes resetting my 8 of 10 day streak of untreated patients...

How does that add up? Cardiac tamponade should be included on the list of possible symptoms so I know to run an Echo or I'm just doing guess work, what in the game leads me to the solution of performing an Echo?

Cardiac tamponade isn't a symptom of the PAD. It's a risk involved with surgery. Your patient didn't get it because of the PAD, but because of the surgery. Now you will not forget it when it hapens in furture.

So... how as a player am I supposed to know if the remaining symptom isn't a symptom but rather a "risk"? The diagnosis tab still has blacked out symptoms so it could be one of them, so while I'm performing all the tests relating the symptoms that it MIGHT be, what leads to me to perform a test for a symptom that there is no mention of or reference to? Oh my patient died while I was trying to work out why none of the tests for symptoms listed worked.

So why have that diagnosis tab at all if the game requires me to memorise or note down every possible "risk" and it's test just on the off chance that it might not be one of the regular symptoms?

To be sure, you could do an ICU blood-test and a physical examination or in case of cardio patients do a heart monitoring to be sure everything went right. Also try to avoid surgeons with skills like hard worker. They do not rest and are tired at the end of the day. The risk of getting complications or PSD seems to depend on the skill of your doctors and their tiredness.