How do you address providers in your referral network that have mismanaged patients?

Hey all

So as I'm finishing my training, I'm struggling more and more on how to delicately correct providers (whether it's MDs, DOs, PAs, NPs or some other letters) that have mismanaged patients. I don't want to lose valuable referral networks by being offending someone, but I also can't stand when providers just aren't thinking or clearly show a deficit in knowledge.

Two recent scenarios:

1. ED consult: A patient with a solitary kidney presented to the ED with acute LLQ. CT showed an 8mm stone at the UVJ. Patient's pain was controlled, and Cr was normal so patient was discharged home. Patient presented back 36 hours, and reports no urine production. Cr quadrupled, patient required admission due to postobstructive diuresis. I called the ED director to discuss the case as this was clearly a deficit in knowledge in the provider, and a solitary obstruction is a surgical emergency.

2. Urology consult: Muscle invasive bladder cancer. A private Urologist had been managing a patient with dysuria and pelvic pain for 3 years. Patient eventually developed gross hematuria and a workup demonstrated a bladder mass consistent with muscle invasive bladder cancer with retroperitoneal adenopathy concerning for metastasis. While reviewing the patient's records, I could find evidence of several years of microscopic hematuria that was not worked up. The reason this is important is because for muscle invasive bladder cancer (non-metastatic), the treatment is neoadjuvant chemotherapy followed by an anterior exenteration with urinary diversion (ileal conduit, neobladder, continent urinary reservoir) . If metastatic, chemotherapy is given. Had this patient been appropriately worked up for their microscopic hematuria, the malignancy may have been caught when it was non-muscle invasive and amenable to transurethral resection with intravesical therapies. Now in this scenario, it is extremely difficult as the provider is within my own specialty, and I will need this providers referrals as I have focus within GU malignancies. I called and talked to this provider, but I think I pissed them off for critiquing their management.