N13 Obstructive and reflux uropathy

ICD-10-CM Code N13: Obstructive and Reflux Uropathy

ICD-10-CM code N13 represents obstructive and reflux uropathy, a urinary tract disorder caused by structural or functional impediments to normal urinary flow. This active diagnosis concept is categorized under renal tubulo-interstitial diseases. The N13 code block encompasses several specific conditions, including various forms of hydronephrosis and hydroureter. 1 2 4

Plain-language overview

Obstructive uropathy is a urinary tract disorder resulting from a structural or functional obstruction of urinary flow, which can lead to urine backflow, increased intrarenal pressure, and potential renal impairment. 2

What this code represents

ICD-10-CM code N13 is an active diagnosis concept representing obstructive and reflux uropathy, classified as a disease or syndrome within the parent category of renal tubulo-interstitial diseases. 1

The N13 code block specifically includes obstructive and reflux uropathy conditions such as hydronephrosis with ureteropelvic junction obstruction, hydroureter, and unspecified obstructive and reflux uropathy. 4

Clinical context

Clinical evaluation of obstructive uropathy involves differentiating it from other causes of renal dysfunction by analyzing clinical presentation, urinalysis, and imaging findings like computed tomography or renal resistive index. 2

Documentation considerations

The World Health Organization classification for N13 explicitly excludes calculus of the kidney and ureter without hydronephrosis, as well as congenital obstructive defects of the renal pelvis. 3

Coverage and utilization context

Using a vague unspecified hydronephrosis code instead of a specific subcode can result in rejected claims, because insurers may not see the medical justification for high-cost procedures like surgery. 5

What the sources add

While terminology records establish the official code hierarchy and active status, billing guides add operational context by illustrating how payer reimbursement depends on selecting specific subcodes rather than unspecified ones. 1 5

Clinical literature defines obstructive uropathy as a structural or functional impediment to urinary flow, whereas coding terminology records define N13 as a broader category encompassing both obstructive and reflux uropathy. 1 2

Sources

1. ICD-10-CM N13 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. Bookshelf — ncbi.nlm.nih.gov; accessed 2026-07-27.
3. ICD-10 Version:2019 — icd.who.int; accessed 2026-07-27.
4. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-27.
5. ICD 10 Code for Hydronephrosis – N13.30 Billing & Compliance Guide | PROMBS — prombs.com; accessed 2026-07-27.