Pyelonephritis

Question 1

Definition

Answer 1

Inflammation of the kidney parenchyma and the renal pelvis

This is usually due to bacterial infection

Question 2

Epidemiology

Answer 2

Highest incidence in women aged 15-29

Question 3

Classifications of pyelonephritis

Answer 3

Uncomplicated = structurally or functionally normal in a non-immunocompromised host

Complicated = opposite

Question 4

Pathophysiology

Answer 4

Neutrophils infiltrate the tubules and the interstitium

This leads to suppurative inflammation.

You can often see small renal cortical abscesses and streaks of pus in the renal medulla.

Question 5

How does bacteria get to the kidneys?

Answer 5

Bacteria can reach the kidney either by ascending from the lower urinary tract, or directly by blood stream like septicaemia or infective endocarditis.

It can also rarely be via lymphatics like in retroperitoneal abscess

Question 6

Common organisms

Answer 6

E. coli (80%)

Klebsiella

Proteus

Enterococcus faecalis

S. aureus

S. saprophyticus

Pseudomonas

Question 7

Risk factors

Answer 7

Obstructed urinary tract and BPH

Spinal cord injury leading to neuropathic bladder

Female gender

Indwelling catheter or ureteric stents and nephrostomy tubes in-situ

Structural renal abnormalities like vesicoureteric reflux.

DM, corticosteroid use, HIV infection

Renal calculi, sexual intercourse and menopause

Question 8

Clinical features

Answer 8

Classic triad = fever, unilateral loin pain and N+V

This typically develops over the course of 24-48h

Patients may also have symptoms of co-existing lower UTI with freq, urgency and dysuria

There may also be visible or non-visible haematuria

Question 9

Examination findings

Answer 9

Often look unwell

Pyrexia

Features of sepsis

Unilateral or bilateral costovertbral angle tenderness and or suprapubic tenderness

Also assess the patient’s fluid status and measure any post-void residual volumes.

Question 10

Dx

Answer 10

Ruptured AAA

Renal calculi

Acute cholecystitis

Ectopic pregnancy

PID

Lower lobe pneumonia

Diverticulitis

Question 11

Investigations

Answer 11

Urinalysis for nitrites and leucocytes

Urinary beta-hCG for all women of child-bearing age.

Urine culture

Routine bloods with FBC and CRP

Question 12

Imaging

Answer 12

All cases should have renal USS to see if there is any obstruction.

If there is obstruction suspected (such as dilation) -> non-contrast CT imaging (CT-KUB) should be done.

Question 13

Management

Answer 13

A-E assessment and appropriate resus.

Start empirical abx based on local protocols (in leicester co-amoxiclav orally for 14 days or ciprofloxacin if pen allergic)
If there is N+V give IV instead.
This should be started as culture are sent off.

Consider admission

Question 14

Management of severe or non-responding cases

Answer 14

Catheterisation and high-dependency unit monitoring.

Consider early CT imaging in such cases to check for any obstruction and complication of pyelonephritis like pyonephrosis or perinephric abscess.

Question 15

Complications

Answer 15

Severe sepsis

Multiorgan failure

Renal scarring -> CKD

Pyonephrosis

Preterm labour

Question 16

What is chronic pyelonephritis?

Answer 16

Repeated infections can lead to chronic Py.

This in its turn leads to fibrosis and will ultimately destroy the kidney.

Question 17

When is it more common to get chronic Py?

Answer 17

In obstructed systems like strictures in UTI, VUR or other anatomical abnormalities which leads to urinary reflux.

Question 18

Diagnosis of chronic Py.

Answer 18

Usually radiologically where you can see a small scarred and shrunken kidney.

Question 19

In what group of people is chronic Py more common?

Answer 19

Structural abnormalities of kidneys

More common in children and they often present asymptomatically or with first presentation being CKD.

Question 20

Management of chronic Py.

Answer 20

Reverse any underlying cause

Optimise renal function

Consider prophylactic abx

Question 21

Explain Emphysematous Pyelonephritis

Answer 21

A rare and severe form of acute pyelonephritis.

It is caused by gas-forming bacteria and is associated with a high mortality rate.

Question 22

Clinical presentation of Emphysematous Pyelonephritis

Answer 22

Similar to acute pyelonephritis

Fail to respond to empirical IV abx

CT imaging will show evidence of gas within and around the kidney.

Question 23

When is Emphysematous Pyelonephritis more common?

Answer 23

Diabetic patients

High glucose allows CO2 production from fermentation by enterobacteria

Question 24

Management of mild Emphysematous Pyelonephritis

Answer 24

Broad-spectrum abx

Question 25

Management of severe Emphysematous Pyelonephritis

Answer 25

Nephrostomy insertion or percutaneous drainage of any collections present

Sometimes nephrectomy will be required.