How I Perform Renal Biopsies

First, the doctors discuss indications and contraindications for biopsy. In the outpatient setting, the doctors have noticed that proteinuria is the most common reason for referral, followed by lupus nephritis. For inpatients, acute unexplained kidney failure is an additional indication. It is important to talk with nephrologists to weigh the risks and benefits of renal biopsy, especially if the patient has a coagulopathy, is experiencing uncontrolled hypertension, or is too unstable to lay prone on the table. The SIR Guidelines app is a useful tool to risk stratify patients.

In terms of imaging, CT or ultrasound can be used, although they each have unique advantages. Ultrasound allows for real-time guidance and the ability to use the probe to hold pressure on the kidney to prevent bleeding. On the other hand, CT allows for better imaging in patients with larger body habitus and allows the patients to lay prone. Dr. Fritts emphasizes that the best imaging modality is the one that the operator is most comfortable with, since this will ensure maximal safety for the patient. One helpful tip when planning a biopsy is to avoid needle entry into the paraspinal muscles, since this could change the trajectory of the needle and cause pain.

Both doctors prefer to use moderate sedation if the patient can tolerate it. This sedation usually has the added benefit of facilitating an intra-procedural blood pressure dip, which protects against bleeding when biopsying hypertensive patients. Since sedation can alter breathing patterns, starting sedation early (before scanning the patient) can be helpful in establishing a steady breathing pattern before the procedure starts. Dr. Beck also recommends checking blood pressure while the patient is in pre-operative care, in order to predict whether or not they might require additional intra-procedural antihypertensive medications such as hydralazine, labetalol, or clonidine. Since blood pressure control is a cornerstone of a safe procedure, each doctor has their own safety threshold for blood pressure.

Then, the doctors discuss different types and sizes of biopsy needles. While a 16G needle can obtain better diagnostic samples, the 18G needle might have a lower risk of bleeding complications. The doctors also share their preferred brands of needles.

The episode concludes with tips for surveilling patients in the post-procedural period and dealing with bleeding complications. Dr. Beck describes his protocol for re-scanning patients to check for large hematomas and keeping them under observation for at least three hours. If there is a large hematoma, emergency embolization must be performed.