UPJO is restriction of urine flow from the renal pelvis to the proximal ureter. Most cases are congenital (often presenting later in life), and neonatal UPJO is usually detected on maternal-fetal ultrasound. This tab covers its etiology, evaluation, and the full range of management — from observation through endopyelotomy to pyeloplasty.
Etiology
UPJO is classed as congenital/primary vs acquired/secondary and intrinsic vs extrinsic.
- Congenital (mnemonic SHAVA): true ureteral Stricture; High insertion (more common with renal ectopia/fusion); Aberrant (crossing) vessels — which lower endopyelotomy success; Kinks or Valves from mucosal/muscular infoldings; and an Aperistaltic segment. In newborns/infants UPJO is usually an intrinsic narrowing (an interruption of the UPJ circular muscle with altered collagen, causing functional discontinuity and poor pelvic emptying); in childhood/adolescence it is often extrinsic, from an accessory lower-pole vessel crossing anterior to the UPJ.
- Acquired (mnemonic CRIBS): Cancer, Reflux (VUR causing elongation/tortuosity/kinking), Ischemia or post-inflammatory/postoperative scarring, Benign lesions (e.g. fibroepithelial polyps), and Stones.
- Associated congenital anomalies include contralateral UPJO (most common), renal dysplasia, multicystic dysplastic kidney, renal agenesis, horseshoe kidney, VUR, and ectopic or duplex kidneys.
- Intermittent UPJO presents as Dietl's crisis — intermittent abdominal pain with nausea/vomiting after high fluid intake. A Lasix renogram may be falsely negative, so compare a renal ultrasound taken during pain to a symptom-free baseline; increased hydronephrosis when symptomatic is diagnostic, and pyeloplasty is curative.
Diagnosis and Evaluation
- Symptoms — periodic loin pain (typically after diuresis), vomiting, recurrent pyelonephritis, fever, and uncommonly an abdominal mass or haematuria.
- Labs — serum creatinine for baseline function.
- Imaging — CT/MR urography for anatomy, plus nuclear diuretic renography (MAG3, especially in children; DTPA in adults) for differential function and obstruction. Kidneys with <15% differential function are generally non-salvageable in adults (some sources use <10%); if salvageability is unclear, place a temporary stent or nephrostomy and repeat the function study.
Management
Indications for intervention (mirroring stone-plus-hypertension): symptoms, stones, infection, renal dysfunction, and causal hypertension. An asymptomatic patient with indeterminate significance can be observed with serial renal scans. Active options are decompression (stent/nephrostomy), endourologic procedures, pyeloplasty, and ureterocalicostomy.
Endourologic Procedures
Balloon dilation and endopyelotomy are less invasive with shorter recovery but carry a higher failure rate than pyeloplasty (percutaneous endopyelotomy succeeds in ~85–90%). Success depends on the degree of hydronephrosis, ipsilateral function, calculi, and crossing vessels — whereas pyeloplasty suits almost any anatomy; moderate-to-severe hydronephrosis most predicts endopyelotomy failure. Transplant-related obstruction is well suited to endoscopic management.
- Contraindications to endopyelotomy: >2 cm of obstruction, untreated UTI, and untreated coagulopathy.
- Approaches — retrograde ureteroscopic (no percutaneous access; direct visualisation) or percutaneous antegrade (allows simultaneous treatment of pyelocalyceal stones). The full-thickness incision is made laterally (devoid of crossing vessels) with an endopyelotome, holmium laser, or cutting balloon, and a stent is left across the incision to heal.
- Follow-up — avoid strenuous activity for 8–10 days; after stent removal, reassess at 1 month with diuretic renography, and follow for 2–3 years (late failures still occur at 36 months). Adverse events: early bleeding, urinary leak, and hydropneumothorax (higher with upper-pole access); late recurrent obstruction.
Pyeloplasty
The anastomosis must be widely patent, watertight, tension-free, healed over a stent, and funnel-shaped for dependent drainage. Absolute contraindications are untreated UTI, uncorrected coagulopathy, and cardiopulmonary unfitness. The transperitoneal laparoscopic/robotic approach is most widely used.
- Dismembered pyeloplasty (Anderson-Hynes) is preferred — universally applicable, it reduces a redundant pelvis, straightens a tortuous ureter, and is the only method that allows transposition of the UPJ relative to crossing vessels (and complete excision of the abnormal UPJ). It is less suited to long/multiple proximal strictures (where a spiral flap helps) or a small intrarenal pelvis.
- Non-dismembered pyeloplasty — the Foley Y-V-plasty repairs a high ureteral insertion, and flap techniques (Culp) are unsuitable with crossing vessels. External drainage is essential to prevent urinoma, suture-line disruption, and sepsis.
- Postoperative care — remove the Foley at 24–36 h and the drain before discharge; if drainage increases after Foley removal, replace it for 7 days. The ureteral stent is removed at 4–6 weeks, with follow-up diuretic renography. Late complications: persistent urinary leak (usually resolves, but a clot needs early drainage — a nephrostomy in children) and recurrent obstruction (most laparoscopic failures occur within 2 years; managed by repeat pyeloplasty or endoscopy).
Ureterocalicostomy
Indicated for UPJO or a proximal stricture with a small intrarenal pelvis, to provide dependent drainage in rotational anomalies (e.g. horseshoe kidney), or as a salvage after failed pyeloplasty. In general, an open/laparoscopic approach is used after failed endourologic treatment, and an endourologic approach after failed open repair.
Self-Test
1. What are the causes of UPJO? Congenital (SHAVA): stricture, high insertion, aberrant vessels, kinks/valves, aperistaltic segment. Acquired (CRIBS): cancer, reflux, ischemia, benign lesions, stones.
2. What are the indications for intervention in UPJO? Symptoms, stones, infection, renal insufficiency, and causal hypertension.
3. What are the options for intervention in UPJO? Observation, decompression (stent or nephrostomy), endoscopic treatment (balloon dilation or endopyelotomy), pyeloplasty, and ureterocalicostomy.
4. How long is a stent kept after pyeloplasty? 4–6 weeks.
5. When should ureterocalicostomy be considered? A small renal pelvis, the need for dependent drainage in a malrotated/ectopic kidney, or a failed pyeloplasty.
6. What are the contraindications to endopyelotomy? Stricture >2 cm, active (untreated) infection, and uncorrected coagulopathy.