What are the complications of infection in association with obstruction of the
upper urinary tract? How is it managed?
Obstruction – block of urine flow through the ureter → distension of renal pelvis and
calyces. Intrinsic / extrinsic
Most common cause of obstruction and infection is stone disease.
Unwell, fever, flank pain and tenderness
This is a urological emergency
Consequences of Infection + Obstruction
Pyonephrosis
Infected hydronephrosis. Pus accumulates in renal pelvis + calyces. Can present
with sepsis or septic shock.
Perinephric abscess
Consequence of extravasation o infected urine outside the parenchyma of the
kidney. Abscess develops in Gerota’s fascia
Emphysematous pyelonephritis
Caused by gas forming organisms (usually E.coli, also klebsiella, proteus). Presents
as severe acute pyelonephritis which fails to respond to antibiotics. Radiographic
evidence of gas within and around kidney.
70 – 90% are diabetic. Presents with a flank mass, rarely surgical emphysema,
hyperglycaemia. Carries a high mortality
Management - IV antibiotics, fluid resuscitation, percutaneous drainage, diabetic
control. If sepsis not controlled – nephrectomy
Xanthalomatous pyelonephritis
Severe infection resulting in destruction of renal tissue and a non-functioning kidney.
Can present acutely with acute flank pain, fever, tender flank mass. Commonly e.coli
and proteus
Fat laden macrophages deposited around abscesses in parenchyma of kidney.
Kidney becomes grossly enlarged, containing yellowish nodules, pus and areas of
haemorrhagic necrosis. On CT difficult to distinguish from RCC (great imitator,
calcification often seen within renal mass).
How is it managed?
Early recognition
Treat sepsis – hydration, appropriate broad spectrum antibiotics, HDU/ITU if septic
shock.
Relieve obstruction –


Retrograde stent
Percutaneous nephrostomy
Two randomised trials have compared retrograde stent insertion with percutaneous
nephrostomy with one trial reporting specifically on patients with acute sepsis and
obstruction. Neither trial showed one superior modality of decompression in effecting
decompression and resolution of sepsis. An overall major complication rate from
percutaneous nephrostomy insertion was found to be 4%, although the complication
rates from stent insertion are less consistently reported. (Ramsey)
Radiologists would prefer more retrograde stent insertions
Potentially higher failure rate, higher cost and anaesthetic risk with retrograde stent
S Ramsey, A Robertson, MJ Ablett, RN Meddings, GW Hollins, B Little. Evidence-Based Drainage of
Infected Hydronephrosis Secondary to Ureteric Calculi: Journal of Endourology: 2010