Pyelonephritis
How the urinary tract normally keeps bacteria out, how gut bacteria climb from the urethra to the bladder and up to the kidney, and why kidney infection causes loin pain, high fever and a real risk of sepsis.
By the end, you can
- Describe the defences that keep the urinary tract sterile above the urethra.
- Explain how bacteria ascend from the perineum to the bladder and kidney, and why some people are more susceptible.
- Explain the inflammation of the kidney that causes loin pain, fever and white cell casts.
- Distinguish pyelonephritis from cystitis by symptoms and mechanism.
- Explain the complications: sepsis, abscess and scarring.
- Recognise the classic appearances of acute and chronic pyelonephritis and its key tests, and explain how antibiotics and drainage act on the mechanism.
What it is
Pyelonephritis is bacterial infection of the kidney’s pelvis and tissue (parenchyma), usually by bacteria that have ascended from the bladder. It is an upper urinary tract infection, distinct from cystitis, which is infection of the bladder alone. Most cases are caused by Escherichia coli.
2 types to tell apart
- Acute uncomplicated
- In otherwise healthy, non-pregnant women with a normal urinary tract.
- Complicated
- With obstruction, stones, catheters, reflux, pregnancy, diabetes, immunosuppression or in men; more severe and more likely to fail treatment.
Normal function
How the urinary tract stays sterile
Urine above the urethra is normally sterile. The main defence is flow: regular, complete emptying of the bladder washes out bacteria before they can multiply. The bladder lining sheds cells with any bacteria attached and secretes substances that stop them sticking.
Where each ureter enters the bladder, at the at the corners of the , it runs obliquely through the wall. When the bladder contracts, this tunnel is squeezed shut, preventing urine from being pushed back up towards the kidney (reflux).
The urethra is a barrier too: the longer it is, the harder for bacteria to reach the bladder through the . This is one reason infections are far more common in women.
Underlying change · Step 1 of 3
Bacteria climb the urinary tract
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 3
The kidney becomes inflamed
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 3 of 3
Sepsis, abscess and scarring
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 3 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .