UPJ Obstruction • Pyeloplasty and approaches

What Is Pyeloplasty? The UPJ Obstruction Surgery, Step by Step

Name: What Is Pyeloplasty? The UPJ Obstruction Surgery, Step by Step
Creator: Prof. Dr. Ali Avanoğlu
Published: 2026-08-19

Pyeloplasty is the operation that repairs the narrow junction (UPJ) between the renal pelvis and the ureter. This page explains why the operation is done, the steps from preparation to discharge, and the question families ask most: "how many surgeries are needed."

Who this is forFamilies whose child has been recommended pyeloplasty and who want to learn step by step what the operation involves

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ByProf. Dr. Ali AvanoğluUpdated19 August 2026

This page is part of UPJ obstruction.Read the full treatment overview on the hub page

Anderson–Hynes pyeloplasty: wide pelvis and narrow UPJ before, funnel-shaped wide junction and JJ stent after

01 · What does pyeloplasty do?02 · Preparation before surgery 03 · How is the operation done? Step by step 04 · Hospital stay and the first days 05 · How many surgeries are needed?

In brief5 madde

What does pyeloplasty do?: UPJ obstruction (ureteropelvic junction obstruction; informally, kidney outlet narrowing) is a slowing of urine flow at the point where the renal pelvis opens into…
Preparation before surgery: Preparation is completed within a few weeks of the decision and is, for most families, simpler than expected.
How is the operation done? Step by step: Whichever approach is chosen (open, laparoscopic, or robotic), the internal steps of the operation are the same.
Hospital stay and the first days: Most children stay in the hospital for a few days after surgery; the length varies with age, approach, and whether a drain is in place.
How many surgeries are needed?: This is the most common question families ask: pyeloplasty is, in the large majority of cases, a one-time repair.

What does pyeloplasty do?

UPJ obstruction (ureteropelvic junction obstruction; informally, kidney outlet narrowing) is a slowing of urine flow at the point where the renal pelvis opens into the ureter. Pyeloplasty removes this narrow point and creates a new, wide, well-draining connection.

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The goal of the operation is not to "fix" the kidney but to remove the obstacle in front of it. Hydronephrosis (kidney swelling) is a finding, not a diagnosis; pyeloplasty comes onto the agenda only when the cause of the swelling is a junction narrowing. This is why the decision is made by evaluating the course of the ultrasound, the results of MAG3 diuretic renography (a kidney scan), and symptoms together; the question Follow-up or surgery? is covered in detail in a separate page.
The most common repair in pediatric urology is Anderson–Hynes (dismembered) pyeloplasty. The narrow segment is removed entirely, and the ureter is reattached to the pelvis.

Preparation before surgery

Preparation is completed within a few weeks of the decision and is, for most families, simpler than expected.

Current ultrasound and MAG3 results are reviewed; bring any older scans with you.
A urine test, and a culture if needed, is done; if there is an active infection, surgery is postponed and treated first.
An anesthesia assessment: blood tests, past illnesses, allergies, and current medications are asked about.
Fasting times are given by the anesthesia team according to age; there are separate times for breast milk and formula in infants.
If your child develops a fever, cough, or diarrhea, let the team know before the day of surgery.

On the morning of surgery your child is brought with you to the preparation area; at most centers the family can stay with the child until anesthesia begins.

How is the operation done? Step by step

Whichever approach is chosen (open, laparoscopic, or robotic), the internal steps of the operation are the same.

General anesthesia is given; the child feels nothing during the operation.
The kidney is reached: a small incision in the flank for the open method, several small openings for closed methods.
The renal pelvis and upper ureter are freed; a crossing vessel, if present, is preserved.
The narrow segment is removed; an overly wide pelvis is reduced if needed.
The end of the ureter is split open a short way (spatulation) and sewn to the pelvis with a wide, watertight opening.
In most cases a JJ (double-J) stent, or a stent brought out through the skin, is placed for the healing period so urine can flow easily; a drain is left in some cases.

The length of surgery varies with age, approach, and anatomy; the team will tell you the expected time at the pre-surgery discussion. Anesthesia preparation and the recovery room are added to your waiting time; seeing your child as they wake is possible at most centers.

Hospital stay and the first days

Most children stay in the hospital for a few days after surgery; the length varies with age, approach, and whether a drain is in place.

Fever (38°C/100.4°F or above), especially with flank pain or vomiting.
Drainage, redness, or increasing pain at the wound site.
A marked decrease in urine output or dark, bloody urine.
Inability to feed, weakness, or vomiting that won't stop.

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Pain control and starting feeding are the focus on the first day. Pain is managed comfortably with age-appropriate pain relievers; with closed methods, pain is generally less and the stay shorter. The urinary catheter and any drain are usually removed in the first days. The JJ stent, however, is removed roughly 4–6 weeks later (2–8 weeks depending on the center) under a brief anesthetic via cystoscopy.
At discharge you'll receive written instructions on wound care, bathing, timing for school or daycare and sports, and check-up dates; Care after pyeloplasty is covered in detail in a separate page. Contact the team without delay in the first weeks after surgery in the following situations.

How many surgeries are needed?

This is the most common question families ask: pyeloplasty is, in the large majority of cases, a one-time repair.

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In the literature, the success of Anderson–Hynes pyeloplasty has been reported at roughly 90–95% or higher; the need for a repeat procedure is on the order of about 3–5%, and most of these arise within the first 1–2 years. This is why ultrasound follow-up after surgery matters especially in the first two years.
That said, the phrase "one operation" does not include stent removal. If a JJ stent was placed, a brief, few-minute cystoscopy procedure is needed a few weeks later under a short anesthetic, usually with same-day discharge; this is a planned complementary step, not a second operation. If an externalized stent was used, removal is done in the clinic without anesthesia.
If the narrowing recurs, redo pyeloplasty or, in selected cases, an endoscopic procedure comes onto the agenda. Continuing with the same two specialists from diagnosis through follow-up is valuable, on the rare occasion a repeat procedure is needed, for having the details of the first operation on hand.

UPJ Obstruction video guide3 short videos, in order

Frequently asked questions

Is pyeloplasty done in babies too?

Yes; when needed, it can be done in the first months of life. In infants, a small-incision open approach is standard at many centers; closed methods are also used at experienced centers. Age alone is not a reason for surgery; the decision is made with function, the course over time, and symptoms.

Does the kidney return to normal after surgery?

The goal is to preserve the kidney's current function and remove the obstruction. Hydronephrosis is not expected to disappear completely; the swelling decreasing can take months, sometimes years. Success is measured by a symptom-free child, decreasing or stable swelling, and preserved function.

Is pyeloplasty a risky operation?

Pyeloplasty is a well-established operation in pediatric urology with well-defined outcomes. Temporary urine leakage, infection, stent-related discomfort, and, rarely, recurrence of the narrowing are the main issues; Complications of pyeloplasty is covered in detail in a separate page. Risks specific to your child are discussed at the pre-surgery consultation.

What happens if we delay the surgery?

Follow-up is a safe option in a kidney with no symptoms and preserved function; surgery comes onto the agenda when follow-up shows a drop in function, increasing swelling, or symptoms. In a symptomatic child, or when loss of function has been documented, delay can lead to loss that does not return. Set the timing together with your team.

Next • Pyeloplasty and approachesAnderson–Hynes (Dismembered) Pyeloplasty→

Related pagesFull index →

Pyeloplasty and approachesAnderson–Hynes (Dismembered) PyeloplastyAnderson–Hynes pyeloplasty is the "dismembered" repair technique in which the narrow UPJ is removed and the ureter is reattached to the renal pelvis. It is the gold standard in both children and adults; this page explains why the technique is preferred and its steps.Pyeloplasty and approachesOpen vs. Laparoscopic vs. RoboticIn UPJ obstruction, all three approaches perform the same operation (Anderson–Hynes pyeloplasty) through different routes of access. This page lays open, laparoscopic and robotic pyeloplasty side by side — on success, pain, hospital stay, scarring, age and cost — without taking sides.After surgery and follow-upJJ (Double-J) StentA JJ (double-J) stent is a temporary, thin tube placed between the kidney and bladder after pyeloplasty; it keeps the newly rejoined junction open while it heals. How long it stays in a child, which symptoms are normal, and how it's removed are among the questions families ask most.After surgery and follow-upAfter Pyeloplasty: Care at HomeThe first days after pyeloplasty raise more questions for most families than the operation itself. This page walks through what happens in the hospital, what the drain and catheter are for, pain, feeding and wound care at home, and when you should call us right away.

UPJ Obstruction topic clustersMain treatment page →

Basics 7 Diagnosis and evaluation 6 Follow-up or surgery? 7 Conservative follow-up 5 Pyeloplasty and approaches 7 After surgery and follow-up 6 By age, and special situations 7

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