Pain, Febrile Infection, or a Stone: The Decision in Symptomatic UPJ Obstruction

Name: Pain, Febrile Infection, or a Stone
Creator: Prof. Dr. Ali Avanoğlu
Published: 2026-08-19

In asymptomatic UPJ obstruction, the decision is usually based on numbers; once a symptom appears, the scale shifts. Recurrent flank pain, febrile urinary tract infection, and kidney stones are listed in guidelines under "symptomatic obstruction" as an indication for pyeloplasty. This page explains how each symptom feeds into the decision.

Who this is forFamilies of children being followed for, or newly diagnosed with, UPJ obstruction who have a history of flank pain episodes, febrile infection, or a stone

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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

eight decision factors; red boxes are the ones highlighted on this page

01 · Why a symptom changes the decision 02 · Recurrent flank pain and Dietl's crisis 03 · Febrile urinary tract infection 04 · If a kidney stone accompanies it 05 · When a symptomatic child should be seen right away

In brief5 madde

Why a symptom changes the decision: In asymptomatic hydronephrosis, surgery is done to prevent a possible future loss of function; this is why the decision is weighed with numbers and the course over time.
Recurrent flank pain and Dietl's crisis: In an older child or adolescent, UPJ obstruction often presents with intermittent obstruction: sudden, severe flank or abdominal pain, nausea, and vomiting after a…
Febrile urinary tract infection: Standing urine in a hydronephrotic kidney creates fertile ground for infection; a febrile infection, meanwhile, is one that affects the kidney tissue itself and can…
If a kidney stone accompanies it: Urine standing in an obstructed pelvis makes stone formation easier; adult UPJ series report roughly 15–20% coexisting stones, and this is rarer in children.
When a symptomatic child should be seen right away: Planned surgery in symptomatic UPJ obstruction is usually scheduled within a few weeks; in our practice, the decision and choice of method are made through the joint…

Why a symptom changes the decision

In asymptomatic hydronephrosis, surgery is done to prevent a possible future loss of function; this is why the decision is weighed with numbers and the course over time. In symptomatic obstruction, the problem is happening today: the child is in pain, has an infection, or is forming a stone.

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The EAU/ESPU guideline lists "symptomatic obstruction" (recurrent flank pain, febrile urinary tract infection) among the leading indications for pyeloplasty. Even if function is above 40% and drainage is acceptable, if a symptom is recurring, the scale tips noticeably toward surgery.
Still, the word "symptom" is used carefully: a single pain episode or a single infection first requires other causes to be ruled out. The guideline's emphasis is on the word "recurring."

Recurrent flank pain and Dietl's crisis

In an older child or adolescent, UPJ obstruction often presents with intermittent obstruction: sudden, severe flank or abdominal pain, nausea, and vomiting after a large fluid intake or increased urine output; between episodes the child looks completely healthy. This picture is called Dietl's crisis, and it can be mistaken for appendicitis or gastroenteritis (a stomach–bowel infection).

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Because ultrasound can look normal between episodes, an ultrasound taken during the pain is very valuable for diagnosis. In this age group, the cause of the obstruction is often a crossing vessel to the lower pole compressing the junction from outside; the literature reports a crossing vessel in close to half of cases with intermittent pain.
Recurrent Dietl's crisis is grounds for pyeloplasty regardless of function; the pain has been reported to resolve in the large majority after surgery. In the operation, the narrowed segment is removed, and the ureter is rerouted in front of the vessel and reattached to the pelvis.

Febrile urinary tract infection

Standing urine in a hydronephrotic kidney creates fertile ground for infection; a febrile infection, meanwhile, is one that affects the kidney tissue itself and can leave scarring. This is why a febrile urinary tract infection against a background of UPJ obstruction is a heavily weighted finding in the surgical decision.

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With a first febrile infection, the cause is investigated first: since kidney reflux (vesicoureteral reflux, VUR) can coexist in UPJ-type hydronephrosis in up to 25% of cases, VCUG (voiding cystourethrogram, informally the catheter study) is requested. If reflux is found, the follow-up and treatment path changes. With a single febrile infection, prophylactic antibiotics and close follow-up can also be an option.
If infections recur, or infection develops in the obstructed kidney itself (infected hydronephrosis), the picture changes: an infected, obstructed kidney is an emergency — drainage first (a temporary stent or nephrostomy) and treatment, then planned pyeloplasty. Recurrent febrile infection is grounds for pyeloplasty even if function is preserved.

If a kidney stone accompanies it

Urine standing in an obstructed pelvis makes stone formation easier; adult UPJ series report roughly 15–20% coexisting stones, and this is rarer in children. A stone affects both symptoms (pain, blood in the urine, infection) and the decision.

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The accepted approach is treating the obstruction and the stone together: during pyeloplasty, while the pelvis is open, stones are removed at the same time (pyelolithotomy or with a flexible nephroscope). Breaking up or removing only the stone does not fix the obstruction, and passing fragments from an obstructed pelvis is also harder — the stone can re-form; repairing only the obstruction, on the other hand, leaves the existing stone behind.
The presence of a stone does not remove the need for a metabolic evaluation: even though the obstruction can promote stone formation, whether an underlying metabolic tendency exists is investigated with urine and blood tests. This evaluation continues independently of the surgery.

When a symptomatic child should be seen right away

Planned surgery in symptomatic UPJ obstruction is usually scheduled within a few weeks; in our practice, the decision and choice of method are made through the joint evaluation of two pediatric urology specialists. The following situations, however, should not wait for the scheduled visit.

Fever (38°C/100.4°F or above) together with flank or abdominal pain: suspicion of an infected, obstructed kidney — same-day evaluation.
Severe, unrelenting flank or abdominal pain with nausea/vomiting; an ultrasound during the pain if possible.
Decreased urine output, swelling, or fatigue in a solitary kidney or bilateral hydronephrosis.
Visible blood in the urine; a baby who cannot feed or is lethargic.
Fever, severe pain, bleeding, or the drainage stopping while a temporary stent or nephrostomy is in place.

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Frequently asked questions

My child had one episode of flank pain; does that require surgery?

A single episode does not decide anything on its own; first it is shown that the episode is linked to UPJ obstruction, an ultrasound during the pain is taken if possible, and other causes are ruled out. If the episodes recur, and especially if MAG3 shows signs of obstruction, pyeloplasty is recommended.

There was a febrile infection but function is 48%; is surgery still needed?

With a single febrile infection, kidney reflux is investigated first with VCUG, and follow-up is considered as an option. If infections recur or develop in the obstructed kidney itself, grounds for pyeloplasty form even if function is preserved, because every febrile infection carries a risk of leaving a mark on the kidney tissue.

If the stone is cleared with shock-wave lithotripsy (ESWL), does the obstruction go away too?

No; lithotripsy breaks up the stone but does not repair the obstruction, and passing fragments from an obstructed pelvis is also harder, so the stone can re-form. This is why the obstruction and the stone are addressed together; removing the stones at the same time as pyeloplasty is the accepted approach.

How soon is surgery scheduled for a symptomatic child?

For recurrent pain or infection, planned pyeloplasty is usually done within a few weeks; this time is needed to complete testing and to operate on the child during an infection-free period. In an infected, obstructed kidney, emergency drainage is done first, and pyeloplasty is left until after recovery.

Doç. Dr. Yaşar Issı's publications on this topic · 1

Resorlu B, Issi Y, Onem K, et al. (2016). Management of lower pole renal stones: the devil is in the details. Annals of translational medicine. PubMed ↗

←Previous • Follow-up or surgery?High-Grade Hydronephrosis (SFU 3–4, UTD P3)Next • Follow-up or surgery?A Very Low-Function Kidney (<20%)→

Related pagesFull index →

BasicsDietl's CrisisDietl's crisis is an attack of severe flank/abdominal pain and vomiting that occurs when UPJ obstruction turns into intermittent complete blockage. The attack lasts for hours and then disappears entirely; between attacks the child, and often the ultrasound too, look completely normal. Because of this, it is frequently missed, and diagnosis relies on an ultrasound taken during the pain.By age, and special situationsUPJ Obstruction and Kidney Stones TogetherIn UPJ obstruction, urine pooling in the renal pelvis (stasis) makes stone formation easier — and a stone can be the first sign of the narrowing. This page explains which comes first, and how the two are treated together when both problems are present.Follow-up or surgery?UPJ Obstruction: Follow-Up or Surgery? How the Decision Is MadeNot every child with UPJ obstruction (ureteropelvic junction obstruction; informally, kidney outlet narrowing) needs surgery. The decision is made from the combination of the kidney's share of function, its emptying speed, the course of the hydronephrosis over time, and any symptoms. This page explains what goes on each side of that scale.Diagnosis and evaluationWhen Is VCUG (Voiding Cystourethrogram) Needed for Suspected UPJ Obstruction?VCUG (voiding cystourethrogram, informally "the catheter study") is not done for every infant with hydronephrosis; when UPJ obstruction is suspected, the real question is "does kidney reflux or a bladder-related problem play a role in this widening?" This page explains when VCUG is recommended, when it isn't routine, and how the result changes the diagnostic path.

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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