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Prof. Dr. Ali Avanoğlu
UPJ Obstruction • Pyeloplasty and approaches

Anderson–Hynes (Dismembered) Pyeloplasty: How Is the Narrow Segment Removed?

Anderson–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.

Who this is forFamilies who hear "Anderson–Hynes" or "dismembered" in the operative report or in a consultation and want to know what the technique involves
Reading≈5 min
ByProf. Dr. Ali AvanoğluUpdated
This page is part of UPJ obstruction.Read the full treatment overview on the hub page
narrow segmentwide pelvisSTEP 1 · narrow segmentwide pelvis, narrowing at the UPJ
pelvis is reducednarrow segment removedureter spatulated on the sideSTEP 2 · excision and reductionexcess pelvis and narrowing removed
wide funnel sutureJJ stent (4–6 weeks)urine flows freelySTEP 3 · re-anastomosisfunnel-shaped, wide junction
Anderson–Hynes three steps: narrow segment marked → excised and pelvis reduced → re-sutured with a wide funnel, JJ stent
01 · What does 'dismembered' mean?02 · The repair, step by step03 · Why is it the gold standard?04 · Limits of the technique and special situations05 · Open, closed, or robotic: does the technique change?
In brief5 madde
  • What does 'dismembered' mean?: "Dismembered" means the ureter is completely separated from the renal pelvis and then re-sewn; in everyday terms, a "disconnected repair."
  • The repair, step by step: Whether the approach is open, laparoscopic, or robotic, the internal sequence is the same.
  • Why is it the gold standard?: Guidelines (EAU/ESPU) refer to Anderson–Hynes dismembered pyeloplasty as the gold standard for repairing UPJ obstruction.
  • Limits of the technique and special situations: Like any technique, Anderson–Hynes has points that require care.
  • Open, closed, or robotic: does the technique change?: No; Anderson–Hynes describes the repair itself, not the route used to reach the kidney.
01

What does 'dismembered' mean?

"Dismembered" means the ureter is completely separated from the renal pelvis and then re-sewn; in everyday terms, a "disconnected repair."

Read the full text
  • UPJ obstruction (ureteropelvic junction obstruction; informally, kidney outlet narrowing) most often arises from a narrow or non-contracting (aperistaltic) segment within the wall of the junction itself. This segment is a pipe with faulty transmission; removing it, rather than widening it, eliminates the source of the problem. This approach, described by Anderson and Hynes, has been a core operation in pediatric urology for decades.
  • The technique's second advantage is flexibility: a wide pelvis can be reduced, a high-inserted ureter can be moved to the lowest point, and, if a crossing vessel is present, the ureter can be rerouted in front of it. This is why it can be applied regardless of the structural type of the narrowing.
02

The repair, step by step

Whether the approach is open, laparoscopic, or robotic, the internal sequence is the same.

  • The renal pelvis and upper ureter are freed from surrounding tissue; a crossing vessel to the lower pole is looked for and preserved.
  • A marking stitch is placed so the ureter's orientation is not confused; the upper and lower borders of the narrow segment are identified.
  • The narrow segment is cut away from the pelvis and ureter and removed; if the pelvis is wide, a portion is taken to reduce it.
  • The end of the ureter is split open a few millimeters along its side wall (spatulation), giving it a wide, funnel-shaped opening.
  • The ureter is sewn, watertight, to the lowest, most dependent point of the pelvis with fine dissolvable sutures (the anastomosis).
  • In most cases a JJ (double-J) stent, or a stent brought out through the skin, is placed to protect the anastomosis; a stentless repair can be done in selected cases.
  • Placing the anastomosis at the "most dependent point" may look like a detail, but it is actually the key refinement: urine flows by gravity from the lowest point; if the connection stays higher up, urine pools in the pelvis. Reducing the pelvis serves the same purpose; an overly wide pelvis can act as a "reservoir" and delay emptying.
03

Why is it the gold standard?

Guidelines (EAU/ESPU) refer to Anderson–Hynes dismembered pyeloplasty as the gold standard for repairing UPJ obstruction.

Read the full text
  • The literature reports success at roughly 90–95% or higher; the need for a repeat procedure is on the order of 3–5%, with most arising in the first 1–2 years. These rates vary by center, age, and case; still, few operations in pediatric urology give results this consistent.
  • Non-dismembered plastic techniques that do not remove the narrow segment, such as flap pyeloplasties, are an option in some special anatomies, especially a long narrowing or a very small pelvis; but because they cannot get past a crossing vessel and leave the narrow tissue in place, they are not first-line. Endoscopic incision (endopyelotomy) and balloon dilation leave the narrow tissue in place and have lower success rates.
04

Limits of the technique and special situations

Like any technique, Anderson–Hynes has points that require care.

Read the full text
  • In a very small pelvis buried within the kidney (intrarenal), a tension-free connection to the ureter can be difficult; in such cases the surgeon may choose another connection during surgery (for example attaching the ureter to the lower calyx, ureterocalicostomy) or a flap technique. In a long-segment narrowing, having enough ureteral length is planned in advance.
  • Temporary slow emptying due to anastomotic swelling is common in the first weeks after surgery; the stent bridges this period. Permanent failure is rare and is mostly a scar narrowing at the anastomosis line; then redo pyeloplasty comes onto the agenda, and its success is again high (roughly 85–95% in the literature).
05

Open, closed, or robotic: does the technique change?

No; Anderson–Hynes describes the repair itself, not the route used to reach the kidney.

  • In an open operation, the same steps are done through a small incision in the flank; in laparoscopic and robotic operations, through several small openings with a camera. Per guideline data, the three routes have comparable success and complication rates; with closed methods, the stay is shorter and pain is less. Which route is chosen is determined by age, weight, anatomy, and center experience through the joint evaluation of two specialists; A side-by-side comparison of the three methods is covered in a separate page.
UPJ Obstruction video guide3 short videos, in order
Frequently asked questions
Doesn't removing the narrow segment shorten the ureter?
The segment removed is usually short, and the ureter's natural elasticity closes the gap. If the pelvis is wide, reducing it lowers the connection point so the suture line stays tension-free. In a long narrowing, the surgeon does additional planning.
Is reducing the pelvis always necessary?
No; it is done to make emptying easier when the pelvis is very wide. In a moderately wide pelvis, most surgeons do not reduce it. The decision is made during surgery based on the anatomy.
Does the hydronephrosis go away right after surgery?
No. The swelling decreases over months; it is not expected to disappear completely. Success is measured by being symptom-free, decreasing or stable swelling, and preserved function; the first check-up ultrasound is usually done at around 3 months.
How is a choice made between Anderson–Hynes and other techniques?
For a first operation in a child, Anderson–Hynes is chosen in most cases. Flap techniques and ureterocalicostomy are for a small intrarenal pelvis, a long narrowing, or a heavily scarred redo case. Endoscopic methods are considered in selected adult and redo cases.
←Previous • Pyeloplasty and approachesWhat Is Pyeloplasty? The UPJ Obstruction Surgery, Step by StepNext • Pyeloplasty and approachesOpen Pyeloplasty: Repair Through a Small Incision in Infants→
Related pagesFull index →
Pyeloplasty and approachesWhat Is Pyeloplasty? The UPJ Obstruction Surgery, Step by StepPyeloplasty 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."Pyeloplasty and approachesIf There's a Crossing VesselA crossing vessel is an extra vessel running to the kidney's lower pole that presses on the ureteropelvic junction (UPJ) from outside. It's a common cause of episodic flank pain in older children and adolescents; this page explains how the vessel changes the operation, and whether it is cut.Pyeloplasty and approachesOpen Pyeloplasty: Repair Through a Small Incision in InfantsOpen pyeloplasty is a repair for UPJ obstruction done by reaching the kidney through a small, several-centimeter incision in the flank. It is the standard approach at many centers for infants; this page explains where the incision is placed, how surgery proceeds, recovery, and the scar.After surgery and follow-upIf the Narrowing Comes Back: Redo PyeloplastyPyeloplasty is a single, lasting operation for most children; but in a small group, the narrowing comes back. This page explains why recurrent UPJ obstruction happens, how it's recognized, and which options exist — redo (repeat) pyeloplasty chief among them.
UPJ Obstruction topic clustersMain treatment page →
Basics 7Diagnosis and evaluation 6Follow-up or surgery? 7Conservative follow-up 5Pyeloplasty and approaches 7After surgery and follow-up 6By age, and special situations 7
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