What is Hydronephrosis?

With the implementation of ICD-10-CM came more codes for reporting diseases and disorders. A lot of these diseases and disorders have combination codes and only require one code for reporting the conditions completely. We have seen a lot of recommendations of late where the coders are coding hydronephrosis, UTI and ureteral stone separately or not with the correct code to include all conditions.


What is Hydronephrosis?

Hydronephrosis is swelling of the kidney that develops due to improper drainage of urine from the kidney to the bladder. This occurs when there is blockage of the outflow or reverse flow (reflux) of the urine. This causes the kidney to swell/enlarge as the urine is unable to pass. Hydronephrosis is due to another disease or disorder and is not considered a primary disease, but a secondary condition.

In the picture below, on the left is a normal kidney/ureter and on the right is hydronephrosis and swelling of the kidney.

Hydronpehrosis is swelling of the kidney that develops due to improper drainage of urine from the kidney to the bladder.

Causes of Hydronephrosis:

Here are some of the most common causes:

  • Infection or inflammation of the urethra or urinary tract (UTI)
  • Kidney stone
  • Congenital disorders
  • Pregnancy
  • Scarring from previous surgery
  • Tumors
  • Blood clot
  • Enlarged prostate

Symptoms of Hydronephrosis:

  • Pain in the abdomen, flank, back and/or bladder
  • Fever/chills
  • Nausea/vomiting
  • Painful urination
  • Incomplete voiding or bladder emptying

Treatment for Hydronephrosis:

Treatment is typically focused on treating the underlying condition by removing the urine buildup, relieving pressure, or clearing the infection. If caused by infection, this would be treated with antibiotics. Some kidney stones can be passed without surgery; however, some may require removal or break-up of the stone for removal/passage. A nephrostomy tube may be used to drain the urine from the kidney, or a catheter may be used to drain the urine from the bladder. The most important thing in treatment of hydronephrosis is to get it addressed as soon as it is known to prevent permanent damage to the kidneys.

Coding of Hydronephrosis:

–obstruction (by) (of)
—ureteral NEC N13.1
—–with infection N13.6
—-calculus N13.2
—–with infection N13.6

When reviewing the medical record, look for potential causes of hydronephrosis such as stone and infection and report based on the ICD-10-CM Alphabetic Index.

Authored by Kim Boy, RHIT, CDIP, CCS, CCS-P

ICD-10-CM Index
ICD-10-CM/PCS Coding Clinic, Second Quarter 2018: Page 21
ICD-10-CM/PCS Coding Clinic, Fourth Quarter 2016: Page 43

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The information contained in this coding advice is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly.

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