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ureteral obstruction

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URETERAL OBSTRUCTION - Medical Keyword Reference

Ureteral obstruction is a blockage in one or both ureters that prevents urine from flowing from the kidneys to the bladder, potentially causing hydronephrosis and kidney damage.123

Short and Long Definitions

Short definition Ureteral obstruction is a blockage in the ureter(s) preventing normal urine drainage from the kidney to the bladder.241

Long definition Ureteral obstruction is a partial or complete blockage of one or both ureters (the muscular tubes connecting the renal pelvis to the bladder) that impairs urine flow, causing upstream accumulation of urine, increased hydrostatic pressure, and progressive hydronephrosis (kidney swelling); can be unilateral or bilateral, acute or chronic, intrinsic (stones, strictures, tumors, blood clots, edema) or extrinsic (masses, fibrosis, aberrant vessels); if untreated, leads to renal dysfunction, infection (pyelonephritis), sepsis, and potentially irreversible kidney damage or failure; commonly occurs at anatomic narrowing points including the ureteropelvic junction (UPJ), pelvic brim (crossing iliac vessels), and ureterovesical junction (UVJ); treatment ranges from conservative management with stenting or nephrostomy drainage to definitive surgical correction depending on etiology and severity.53612

Etymology

  • Ureter: From Greek ourētḗr (οὐρητήρ) = “urinary canal” (from oûron “urine”).
  • Obstruction: From Latin obstructio = “blockage, barrier” (from obstruere “to block up” - ob- “against” + struere “to build”).
  • Literal: “Blockage of the urinary canal.”

Classification by Location

LocationDescriptionCommon Causes
Ureteropelvic Junction (UPJ)Where renal pelvis meets ureter (most common congenital site).36Congenital narrowing, crossing vessel, high insertion, stricture.
Mid-ureterAlong course over iliac vesselsExternal compression (tumors, retroperitoneal fibrosis), stones.
Ureterovesical Junction (UVJ)Where ureter enters bladder1Ureterocele, stricture, impacted stone, bladder tumors.
Multiple sitesDiffering segmentsMalignancy, retroperitoneal fibrosis.

Coding Context

ICD-10-CM:

CodeDescription
N13.0Hydronephrosis with ureteropelvic junction obstruction.
N13.1Hydronephrosis with ureteral stricture, NEC.
N13.5Crossing vessel and stricture of ureter without hydronephrosis.
N13.6Pyonephrosis (infected obstructed kidney).
N13.8Other obstructive and reflux uropathy.
N20.1Calculus of ureter (stone causing obstruction).
N11.1Chronic obstructive pyelonephritis.
Q62.0Congenital hydronephrosis.
Q62.11Congenital occlusion of UPJ.
Q62.2Congenital megaureter (dilated ureter).

CPT Codes (Procedures):

CodeDescription
50400Pyeloplasty (UPJ repair); congenital or secondary.
50405Pyeloplasty with ureteroureterostomy.
50432-50433Placement nephrostomy/nephroureteral catheter percutaneous.
52310-52315Cystourethroscopy with removal ureteral calculus (stone).
52332Cystourethroscopy with insertion indwelling ureteral stent.
52334Cystourethroscopy with insertion ureteral guide wire.
50780Ureteroneocystostomy (ureteral reimplantation).
50740Ureteropyelostomy (anastomose ureter to kidney).
52345Cystourethroscopy with ureteroscopy; stricture treatment with dilation.

Etiology and Causes

Intrinsic causes (within ureter):3712

  • Calculi (stones): Most common acute cause; calcium oxalate, uric acid.
  • Strictures: Scarring from trauma, surgery, radiation, infection, ischemia.
  • Tumors: Urothelial carcinoma (transitional cell), metastases.
  • Blood clots: From trauma, coagulopathy, anticoagulation.
  • Fungal balls: Candida bezoars (immunocompromised).
  • Sloughed papillae: Papillary necrosis (diabetes, sickle cell, analgesic abuse).
  • Congenital: UPJ/UVJ obstruction, ureterocele, megaureter.6

Extrinsic causes (external compression):756

  • Malignancy: Cervical, colorectal, bladder, prostate, lymphoma.
  • Retroperitoneal fibrosis: Idiopathic (Ormond disease), drugs (methysergide), radiation.
  • Vascular: Crossing renal vessels, iliac artery aneurysm, ovarian vein syndrome.
  • Gynecologic: Pregnancy (physiologic hydroureteronephrosis), endometriosis, ovarian masses.
  • Inflammatory: Crohn’s disease, diverticulitis, appendicitis.
  • Iatrogenic: Surgical injury during hysterectomy, colorectal surgery.

Clinical Features

Symptoms:412

  • Renal colic: Acute severe flank pain radiating to groin (acute obstruction from stone).
  • Chronic dull flank/back pain: Gradual obstruction.
  • Hematuria: Gross or microscopic.
  • Decreased urine output: Oliguria (bilateral) or anuria (complete bilateral or solitary kidney).
  • Nausea, vomiting: From pain, uremia.
  • Fever, chills: If infected (pyonephrosis - emergency).
  • Hypertension: From renin release.
  • Palpable flank mass: Severe hydronephrosis.

Physical examination:

  • Costovertebral angle (CVA) tenderness.
  • Abdominal/pelvic mass (if severe hydronephrosis or extrinsic tumor).
  • Fever (infection).
  • Hydronephrosis: Kidney swelling from urine backup.16
  • Hydroureter: Ureteral dilation proximal to obstruction.
  • Pyonephrosis: Infected obstructed kidney (pus in collecting system).1
  • UPJ obstruction: Ureteropelvic junction blockage (congenital or acquired).36
  • UVJ obstruction: Ureterovesical junction blockage.1
  • Ureterocele: Cystic dilation of distal ureter bulging into bladder.51
  • Stricture: Scarred narrowing of ureter.73
  • Megaureter: Congenitally dilated ureter.5
  • Vesicoureteral reflux (VUR): Backward urine flow from bladder to kidney.
  • Renal colic: Severe colicky pain from acute obstruction.

Diagnostic Workup

Laboratory:

  • Urinalysis: Hematuria, pyuria, bacteriuria, crystals.
  • Urine culture: If infection suspected.
  • BMP/creatinine: Assess renal function (elevated Cr if bilateral or solitary kidney).
  • CBC: Leukocytosis if infected.

Imaging:75

  • Renal ultrasound: First-line; visualizes hydronephrosis, safe in pregnancy/children.
  • Non-contrast CT (CT KUB): Gold standard for stones; shows level/cause of obstruction.
  • CT urography: Contrast-enhanced detailed anatomy.
  • MR urography: Pregnancy, contrast allergy.
  • Renal nuclear scan (MAG3/DTPA): Assess differential kidney function, drainage.
  • Retrograde pyelography: Direct contrast via cystoscopy; diagnostic and therapeutic.
  • Antegrade pyelography: Via nephrostomy tube.

Management and Treatment

Emergency management (if infected/bilateral/solitary kidney):5

  • Ureteral stent (52332): Internal drainage bypassing obstruction.
  • Percutaneous nephrostomy (50432): External drainage via flank puncture.
  • Antibiotics: Broad-spectrum IV if pyonephrosis/sepsis.

Definitive treatment (by cause):75

CauseTreatment
Ureteral stoneESWL, ureteroscopy with laser lithotripsy (52310-52315), basket extraction.
UPJ obstructionPyeloplasty (50400 open/laparoscopic/robotic); endopyelotomy.
StrictureBalloon dilation, endoureterotomy, ureteroplasty, ureteral reimplantation (50780).7
UreteroceleEndoscopic incision, ureteral reimplantation.
MalignancyStenting (palliative), surgical resection/reconstruction, chemotherapy/radiation.
Retroperitoneal fibrosisSteroids, ureterolysis (surgical release).
PregnancyConservative (resolves postpartum); stent if symptomatic.

Complications

Acute complications:

  • Obstructive pyelonephritis/pyonephrosis: Life-threatening sepsis (requires urgent drainage).1
  • Acute kidney injury (AKI): Bilateral obstruction or solitary kidney.
  • Urinoma: Urine leak from forniceal rupture (high pressure).
  • Sepsis, death: If untreated infected obstruction.21

Chronic complications:

  • Chronic kidney disease (CKD): Irreversible nephron loss.
  • Hypertension: Renin-mediated.
  • Recurrent UTIs/pyelonephritis.
  • Stone formation: Stasis promotes calculi.

Prognosis

  • Early relief (<2 weeks): Excellent recovery of renal function.1
  • Prolonged obstruction (>6 weeks): Progressive irreversible damage.
  • Bilateral complete obstruction: Fatal without intervention (anuria, uremia).
  • Infected obstruction: High mortality if drainage delayed.

One-Sentence Summary

Ureteral obstruction (N13.0/N13.1, Latin/Greek ureter-obstructio “urinary canal blockage”), partial/complete ureteral blockage from stones (N20.1), strictures, tumors, or congenital UPJ (Q62.11) causing hydronephrosis/pain/infection, diagnosed via ultrasound/CT, treated emergently via stent (52332)/nephrostomy (50432) then definitively by pyeloplasty (50400), lithotripsy, or ureteroplasty depending on etiology.623571

Document created: February 13, 2026 Medical coding professional reference 8910

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Footnotes

  1. https://www.mayoclinic.org/diseases-conditions/ureteral-obstruction/symptoms-causes/syc-20354676 ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14

  2. https://my.clevelandclinic.org/health/diseases/21155-ureteral-obstruction ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7

  3. https://healthcare.utah.edu/urology/conditions/ureteral-stricture-obstruction ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7

  4. https://ugatl.com/blog/ureteral-obstruction/ ↩ ↩2

  5. https://www.uofmhealthsparrow.org/departments-conditions/conditions/ureteral-obstruction ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8

  6. https://www.ncbi.nlm.nih.gov/books/NBK560740/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7

  7. https://www.saintjohnscancer.org/urology/conditions/urinary-obstruction-urologic-reconstruction/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7

  8. https://emedicine.medscape.com/article/438890-overview ↩

  9. https://www.ummhealth.org/services-treatments/urology/uteteral-obstruction ↩

  10. https://www.clinpgx.org/disease/PA445981 ↩

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