Urology Coding Alert

Improving your knowledge of urinary system stones will save you denials in the long run.

Coding for stones in a patient’s urinary tract can be a complex task, given their different anatomical locations and the different terminology providers can use to refer to them. These complications can lead to inaccuracies, impacting claim reimbursement.

This article aims to shed light on a few common coding myths related to urinary tract stones, providing practical solutions and strategies to correct them. By understanding and addressing these issues, you can enhance your coding accuracy and improve claim approvals.

Myth 1: The location of the stone doesn’t affect the diagnosis code.

Truth: The location of the stone in the urinary system can change the code. For instance, a stone in the kidney is coded differently than a stone in the ureter.

The initial step in choosing the appropriate diagnosis code involves identifying the exact location of the stone. These stones, also known as a calculus (singular) or calculi (plural), can be found in different parts of the urinary tract. Therefore, it’s inaccurate to categorize all of them as either kidney stones or bladder stones.

To help code these urinary tract conditions more quickly, all you have to do is notice that the codes move sequentially from the top of the urinary tract, starting with the kidneys, and end at the bottom with the urethra. “It’s very important to make sure the physician indicates the location of the stone for the correct diagnosis code, but it’s equally important for the size of the stone to be documented as well to make sure the appropriate CPT^® code is assigned when applicable,” says Stephanie Storck, CPC, CPMA, CUC, CCS-P, ACS-UR, longtime urology coder and consultant in Glen Burnie, Maryland.

Examples of common stone locations and their corresponding ICD-10-CM codes include:

• N20.0 (Calculus of kidney)
• N20.1 (Calculus of ureter)
• N20.2 (Calculus of kidney with calculus of ureter)
• N20.9 (Urinary calculus, unspecified)
• N21.0 (Calculus in bladder)
• N21.1 (Calculus in urethra)
• N21.8 (Other lower urinary tract calculus)
• N21.9 (Calculus of lower urinary tract, unspecified)
• N22 (Calculus of urinary tract in diseases classified elsewhere)

Myth 2: Only use N20.0 when your provider documents kidney stones.

Truth: It’s important to pay attention to the language your practitioner uses in their notes to code the stone correctly. That’s because the language your urologist uses in their reports might differ from the terminology used in the ICD-10-CM code set.

For example, instead of using the term “kidney stone,” your provider may document a staghorn calculus, a renal calculus, a renal stone, or even nephrolithiasis. But a quick look at the inclusion terms found under N20.0 (Calculus of kidney) will tell you that all of these conditions are just different terms for a kidney stone.

Myth 3: You can use N13.2 if a patient has both renal and ureteral stones.

Truth: You cannot use N13.2 (Hydronephrosis with renal and ureteral calculous obstruction) because the patient must also have hydronephrosis before you can use this code. Even though the term “calculous” in the descriptor for N13.2 indicates that this diagnosis code pertains to a condition involving stones, this code only applies when the stone is accompanied by hydronephrosis, a condition that causes the kidneys to swell due to urine buildup. If hydronephrosis is caused by a renal/ureteral stone that’s obstructing flow, then you’ll turn to N13.2.

Remember you shouldn’t report both N13.2 and N20.0 when the urologist sees patients with hydronephrosis due to a kidney stone. There is an Excludes1 note following N20 that instructs you to report N13.2. If a patient has both renal and ureteral stones, you’ll use N20.2 along with N21.1 to report both conditions.

Helpful tip: ICD-10-CM guideline A.12.a states an Excludes1 note is a “pure exclusion note” and that you cannot code the two linked conditions together because they cannot exist together. So, if your provider documents both a condition coded to N20.- and N13.2, you would only report N13.2. Or to put it another way, per ICD-10-CM Coding Clinic Volume 5, Number 4 (2018), you should “assign only the code referenced in the Excludes1 note.”

Myth 4: The patient’s symptoms don’t affect diagnosis code choice.