My Clinical Approach to UPJ Obstruction
UPJ obstruction is a condition typically discovered either incidentally on imaging or during the workup of recurrent loin pain or urinary tract infections. The challenge is not just diagnosis but making the right decision: surveillance or intervention?
At my urology practice in Rhodes I specialise in laparoscopic Anderson-Hynes pyeloplasty — the gold-standard procedure for symptomatic or functionally significant UPJ obstruction. The decision for surgery is always based on a combination of clinical findings and objective renal function measurement by scintigraphy.
- Renal scintigraphy (MAG3) to measure split renal function and confirm obstruction.
- CT urography to identify crossing vessels and map the anatomy before surgery.
- Laparoscopic/robotic pyeloplasty as standard — hospital stay 1–2 days.
- Endopyelotomy for selected recurrences or selected primary cases.
What is UPJ Obstruction
Ureteropelvic junction (UPJ) obstruction is a blockage of urine flow from the renal pelvis into the ureter at their junction. It is the most common cause of hydronephrosis in children and young adults.
The resulting hydronephrosis — dilatation of the renal pelvis and calyces — can lead to progressive damage of the renal parenchyma if the obstruction is not corrected. Hydronephrosis may also be detected prenatally on foetal ultrasound. See: hydronephrosis.
Prevalence
Occurs in ~1 in 1,000–2,000 children — male:female ratio 2:1. Left-sided predominance (60%). Bilateral UPJ obstruction in ~10–15%.
Causes & Pathophysiology
We distinguish intrinsic and extrinsic causes:
Intrinsic Stenosis (Congenital) — most common
Abnormal development of the pelviureteric segment: fibrosis, deficient peristaltic muscle, or high ureteric insertion. Diagnosis is often made in infancy/childhood or at presentation in early adulthood.
Crossing Vessel — ~35–40%
An anterior branch of the renal artery or vein crosses the UPJ, causing extrinsic compression. Determines the surgical technique required (transposition pyeloplasty).
Acquired Causes
Urolithiasis (stone at the UPJ), chronic UTIs, surgical scarring, or external compression by a lymph node or tumour. See: kidney stones.
Symptoms & Clinical Presentation
The clinical picture depends on the degree of obstruction and age at presentation:
Dietl's Crisis
Typical symptom: severe intermittent loin pain, often occurring after a large fluid intake or alcohol consumption. Accompanied by nausea and vomiting. Pathognomonic for UPJ obstruction.
Asymptomatic Hydronephrosis
Particularly in infants and children — hydronephrosis is discovered incidentally on prenatal or postnatal ultrasound with no symptoms.
Haematuria
Macroscopic or microscopic haematuria, especially after trauma or physical exertion. See: haematuria.
Recurrent Urinary Tract Infections
Urinary stasis promotes bacterial growth. Recurrent pyelonephritis without an obvious cause should prompt imaging to exclude UPJ obstruction. See: pyelonephritis.
Untreated Hydronephrosis Leads to Irreversible Renal Damage
Prolonged UPJ obstruction with ipsilateral split renal function <20–25% is an indication for prompt surgical intervention. Delay can result in end-stage renal disease or nephrectomy. Required:
- Renal scintigraphy (MAG3/DTPA) for objective measurement of renal function and obstruction.
- Urgent urological assessment in acute pyelonephritis with hydronephrosis.
- Nephrostomy in septic UPJ obstruction to relieve obstruction before definitive surgery.
Diagnosis & Imaging
Diagnosis of UPJ obstruction relies on a combination of anatomical and functional investigations:
Renal Ultrasound
Primary investigation — detects hydronephrosis, measures pelvic diameter. Does not assess function or degree of obstruction. Suitable for screening and surveillance.
CT Urography (CTU)
Detailed anatomical imaging — identifies crossing vessels, stones, and any mass lesion. Essential before surgery for vascular mapping.
Renal Scintigraphy (MAG3/DTPA)
Gold standard for measuring: (a) split renal function — percentage contribution of the ipsilateral kidney, and (b) drainage t½ to confirm obstruction. Decisive for treatment decisions.
MRI Urography
CT alternative without radiation — ideal for children and pregnant patients. Excellent delineation of anatomy and crossing vessels.
Hydronephrosis Grading (SFU)
The Society for Fetal Urology (SFU) classifies hydronephrosis into 4 grades on ultrasound:
SFU 1
MildMild pelvic dilatation without calyceal dilatation. Typically no intervention required — surveillance.
SFU 2
ModeratePelvic dilatation with mild calyceal dilatation, no parenchymal thinning. Scintigraphy for functional assessment.
SFU 3
SignificantMarked pelvic and calyceal dilatation with early parenchymal thinning. Usually an indication for surgery if split function <40%.
SFU 4
SevereSevere dilatation with marked parenchymal thinning. Urgent surgical assessment — risk of irreversible renal damage.
Treatment Options
The treatment decision is based on clinical symptoms, split renal function, and degree of hydronephrosis:
Conservative Surveillance
For asymptomatic hydronephrosis SFU 1–2 with ipsilateral split function >40% and normal drainage t½. Ultrasound and scintigraphy every 6–12 months. Surgery indicated if function deteriorates or symptoms develop.
Anderson-Hynes Pyeloplasty — Treatment of Choice
Excision of the stenotic UPJ segment + redundant pelvis trimming + dismembered re-anastomosis. Success rate >90–95%. Indications: symptomatic UPJ obstruction, split function <40%, recurrent infections, nephrolithiasis, or worsening hydronephrosis.
Endopyelotomy
Antegrade (nephroscopy) or retrograde (ureteroscopy) incision of the stenotic segment. Lower success rate (~70–85%) compared to pyeloplasty — used in selected recurrences or inoperable patients.
Surgical Management
Laparoscopic/robotic pyeloplasty is the current standard of care:
Laparoscopic / Robotic Anderson-Hynes Pyeloplasty
Excision of the stenotic UPJ + trimming of the redundant pelvis + dismembered re-anastomosis. Transposition of the new anastomosis anterior to any crossing vessel. JJ stent placed for 4–6 weeks.
Antegrade Endopyelotomy (Percutaneous)
Under nephroscopic guidance — full-thickness incision of the UPJ with electrosurgery or laser. Option for recurrences or short stenosis (<2 cm) without a crossing vessel.
Retrograde Endopyelotomy (Ureteroscopy)
Ureteronephroscopy with laser incision of the UPJ — less invasive. Applied in selected cases, particularly recurrences with short-segment stenosis.
Nephrostomy (Temporary Drainage)
In septic UPJ obstruction or acute renal failure from obstruction — nephrostomy placement under CT guidance for immediate decompression. Definitive surgical repair performed at a second stage.
Follow-up & Prognosis
After pyeloplasty, follow-up is structured:
- JJ stent removal at 4–6 weeks post-operatively.
- Renal ultrasound at 6 weeks — assessment of hydronephrosis improvement.
- MAG3 scintigraphy at 3 months — confirmation of improved split function and drainage.
- Annual ultrasound for 3–5 years to exclude recurrence.
- Scintigraphy at 1 year if baseline split function was <40% — assess recovery.
Prognosis
Anderson-Hynes pyeloplasty delivers excellent results — success rate >93–95% in referral centre series. Renal function improves or stabilises in the vast majority. Even kidneys with <20% split function can show significant recovery after the procedure.
Frequently Asked Questions (FAQ)
What is ureteropelvic junction obstruction?
Ureteropelvic junction (UPJ) obstruction is a blockage at the point where the renal pelvis meets the ureter. It causes hydronephrosis — dilatation of the pelvis due to impaired urine outflow — and, if untreated, leads to progressive loss of renal function.
Is UPJ obstruction congenital or acquired?
Both. The congenital form (most common causes: intrinsic stenosis, crossing vessel compressing the ureter) is most frequent. Acquired causes include urolithiasis, urinary tract infections, surgical scarring, and external compression by a tumour.
What symptoms does UPJ obstruction cause?
Most commonly: intermittent loin pain (Dietl's crisis), nausea, and vomiting — particularly after large fluid intake. Large hydronephrosis can be completely asymptomatic. Complications include urinary tract infections, nephrolithiasis, hypertension, and loss of renal function.
Does UPJ obstruction always require surgery?
No. Asymptomatic hydronephrosis with preserved renal function (>40% ipsilateral) is managed conservatively with surveillance. Surgery is required for: symptomatic disease, split renal function <40%, recurrent infections, nephrolithiasis, or worsening hydronephrosis.
What is Anderson-Hynes pyeloplasty?
Anderson-Hynes pyeloplasty is the definitive surgical procedure for UPJ obstruction — excision of the stenotic segment followed by dismembered re-anastomosis of the pelvis and ureter. Success rate >90–95%. Today performed primarily laparoscopically or robotically.
What is a crossing vessel and does it affect the operation?
A crossing vessel (anterior branch of the renal artery or vein) is found in ~35–40% of UPJ obstruction cases. It is not a contraindication to pyeloplasty — but requires a transposition technique (the new anastomosis is placed anterior to the vessel).
How quickly does one recover after laparoscopic pyeloplasty?
Hospital stay 1–3 days. The internal JJ stent is removed at 4–6 weeks. Return to normal activities within 2–3 weeks. Renal scintigraphy at 3 months to assess the result.
Can UPJ obstruction recur after surgery?
Recurrence occurs in <5–10% after successful pyeloplasty. Risk factors include: unaddressed crossing vessel, ischaemia at the anastomosis, and a long stenotic ureteric segment. Endopyelotomy is an option for recurrence.
Related Topics
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Diagnosed with UPJ obstruction or hydronephrosis? Individualised assessment and laparoscopic pyeloplasty are available at the urology practice in Rhodes.
References – Sources
- EAU Guidelines on Obstructive Uropathy 2024 — uroweb.org
- Tan BJ, Smith AD. Ureteropelvic junction obstruction repair: when, how, what outcome? Curr Opin Urol 2004;14:55–59.
- Inagaki T, et al. Laparoscopic pyeloplasty: current status. BJU Int 2005;95(Suppl 2):102–5.
- Piaggio LA, et al. Comparison of laparoscopic and open dismembered pyeloplasty in the pediatric patient. J Urol 2007;177:2175–80.
- EAU Paediatric Urology Guidelines 2024.
Medical Review
Dr. Marinos Vasilas, Urologist – Andrologist
Dr. Marinos Vasilas runs a private urology practice in Rhodes with expertise in laparoscopic/robotic pyeloplasty, hydronephrosis management, and obstructive uropathy. He follows the EAU Guidelines 2024.
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