Kidney Biopsy

5 Points to Help Understand the Procedure

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What is a Kidney Biopsy?

The word biopsy is a combination of the words "bios" and "opsis." It was coined by a French dermatologist wherein "bios" implies life, and opsis implies "to see." Therefore, a biopsy is a physician's way of directly looking at a piece of tissue from an organ and answer questions about diagnosis. Unlike imaging studies like x-rays or CT scans, a biopsy is a direct visualization of a disease process, where you're "not just looking at shadows".

Doing a kidney biopsy involves sticking a needle into the kidney to get a tiny piece of the tissue. Later the tissue is put on a slide, stained, and visualized under a microscope.

When a Biopsy is Required

The short answer would be when you have unanswered questions about diagnosis. As we have discussed in other articles, kidney disease does not come with a specific set of symptoms and when symptoms do occur, they can be extremely vague (like fatigue, itching or even nausea). The usual lab tests that we have to assess your kidney function (including blood tests, urine tests, or imaging studies like kidney ultrasounds or CT scans) might not give a complete diagnostic answer.

For instance, a person could present with signs of kidney disease because they have either blood in the urine or because their toxin level in the blood is elevated. These findings will usually tell us that you have something wrong with your kidneys, but might not tell us why or what is causing that.

Answering this why is important because treatment depends on it.

For instance, blood in the urine can happen because of either kidney stones, or from kidney cancer, or even from kidney infections. As you might imagine, the treatment for all of these situations is entirely different.

The Signs a Biopsy Might be Required

Undiagnosed or underdiagnosed conditions presenting with the following could require a kidney biopsy:

The Procedure

Without going too much into the technical details, here is an overview. An informed consent would be required for the procedure.

The ideal way to do a kidney biopsy is to do it under direct visualization. In other words, the physician will first locate the kidney using real-time CT scan or ultrasonography imaging. Once they can see the kidney, they will insert a needle through your skin, all the way into the kidney. Patients will typically lie on their stomach, although it's possible to do the procedure with them sitting up as well. The site of entry is usually your flanks.

This needle is hollow and within it, has a lancet with a trigger mechanism. This lancet has the ability to go into the kidney, pluck a small piece of tissue out, and then retract back into the hollow outer needle.

Once a satisfactory sample has been obtained, the needle is withdrawn.

Typically, the procedure is not carried out under general anesthesia. Local numbing medications are more than enough. The actual procedure and the preparation time usually lasts for about an hour.

A kidney biopsy will not require you to be admitted to the hospital in most cases. However, it would require you to lie on your back in a post-procedure room for up to 4 hours. One could expect to see some blood in the urine later, but it should clear up gradually in about 24 hours.

Final Word of Caution

There are certain things you might want to pay attention to before the procedure. Since a kidney biopsy involves sticking a needle into a very vascular organ, it is preferred that most patients do not be under any kind of blood thinners before the procedure is done. Medications like aspirin or other other blood thinners like clopidogrel (Plavix) might need to be held well before the procedure to minimize bleeding risk.

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