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Radiology
Duplicated Collecting System
Built from Obstetric Imaging
What’s inside
9 sections · 60 slides
Overview
- What this session covers
What a duplex kidney is
Building the idea from the plumbing upwards
- Start with the normal drain
- Now double the plumbing
- Two ways the doubling can end
- Complete versus incomplete, in words
- The cyst at the end of the pipe
- Often harmless, sometimes not
- How it can show itself before birth
How common it is
Numbers from prenatal series and from autopsy
- 1:2000
- Reading those numbers
- Far commoner than the scans suggest
- What a systematic review found on scan
- Who has it, and how reliable is the call
- Is it inherited, and does it need genetic testing
How it forms
Embryology, and why the two ureters behave differently
- The bud that becomes the drain
- Complete duplication, step by step
- Incomplete duplication, step by step
- The rule that tells you where each ureter lands
- Two ureters, two different problems
- Why the top half gets blocked
- Where else the upper pole ureter can end
- Why the bottom half refluxes
- Incomplete duplication is not risk-free
How it presents
Before birth on the scan, and afterwards in the clinic
- Ways a duplex kidney comes to attention
The ultrasound examination
Scanning technique, the classic signs, and the traps
- Scan each kidney in more than one plane
- Two pelves with a band of tissue between them
- How much swelling should you expect
- A duplex kidney across four views
- Duplex kidney in sagittal, transverse and Doppler views
- Sagittal view catching both moieties in one image
- Colour Doppler showing the fluid-filled tube is a ureter, not a vessel
- Follow the ureter, but know the limit
- An enlarged kidney with a swollen upper pole ureter
- Looking for the cyst inside the bladder
- Ureterocele inside the fetal bladder
- When a ureterocele blocks the bladder outlet
- When both kidneys are involved
- A ureterocele is a clue, not a diagnosis on its own
- The quiet duplex kidney with nothing dilated
- Two renal pelves and two renal arteries
- Two renal arteries perfusing one kidney on colour Doppler
- Size and shape are diagnostic clues too
- What to hunt for on the scan
- The classic signs, gathered
What else it could be
The differential diagnosis from the imaging findings
- Other causes of a dilated fetal renal pelvis
- Telling them apart
After birth
Investigation, outcomes, and treatment options
- How a newborn is worked up
- The postnatal tests explained
- 50%
- Reading the outcome figures
- The main payoff of diagnosing it early
- Which features push towards surgery
- What the operations are
The messages to keep
What the referring clinician needs, and the key points
- What the referring physician needs to know
- Key points
- One picture to carry away
- References
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition