ICD 10 Coding Alert

Look to the N20-N22 codes, but don’t forget to see whether N13.2 fits, too.

Selecting the most accurate diagnosis code for kidney, bladder, or ureter stones means choosing among dozens of choices. Ensuring that the patient’s medical record reflects their actual condition — and proving medical necessity for your provider’s services — are both important aspects of choosing the right code.

Try these tips to make the code selection easier.

1. Laser in on Location

Your first step in selecting a code will be to pinpoint where the stone was located. Also referred to as a calculus (one stone) or calculi (multiple stones), these can occur in various locations along the urinary tract, so you can’t assume that they’re all reported as kidney stones or bladder stones.

Check out this list of the most common locations, along with the corresponding code family:

• 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)

You’ll note that the final code on this list (N22) requires you to first code the underlying disease. For instance, if the patient has gout, you’ll report a primary code from the M1A-M10 series, followed by N22.

2. Know When Alternate Terminology Applies

If you read through the above list with more questions than answers, that may mean that your urologist uses different terminology in their reports than the ones reflected in the ICD-10-CM code set. Check out these pointers to better correlate your physician’s potential terminology with the right codes.

• Nephrolithiasis NOS (N20.0)
• Renal calculus (N20.0)
• Renal stone (N20.0)
• Staghorn calculus (N20.0)
• Stone in kidney (N20.0)
• Calculus of the ureteropelvic junction (N20.1)
• Ureteric stone (N20.1)
• Calculus in diverticulum of bladder (N21.0)
• Urinary bladder stone (N21.0)

If you see terminology in the physician’s report of a stone or calculus but the location doesn’t correspond to these terms or the ones in the code descriptors, query the urologist for more information about location so you can select the right code.

3. Consider N13.2

When you’re scanning the ICD-10-CM code set, you’re sure to notice N13.2 (Hydronephrosis with renal and ureteral calculous obstruction). Because the descriptor refers to “calculous,” it’s clear that this diagnosis code describes a condition that includes a stone. However, there are some key differences to note between this code and the main stone codes listed above.

First, you’ll never report N13.2 for a basic renal or ureteral stone. Instead, this code 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.

Plus, keep in mind that you should not report both N13.2 and N20.0 when the urologist sees patients with hydronephrosis due to a stone. The ICD-10-CM code book clearly lists an Excludes2 note following N20 that excludes you from reporting this code with N13.2.

Therefore, if you see a patient with hydronephrosis and renal/ ureteral calculous obstruction, you’ll report just N13.2.

                                                                                                                        Torrey Kim, Contributing Writer, Raleigh, N.C.