Lecture 10: Radiology of the Renal Tract Flashcards
Role of imaging
- History: Listen, Question, Diagnose (90%)
2. Tests: Imaging to confirm diagnosis (+ additional specific location) or find something new
6 Types of Imaging
- Plain Film/X-ray
- Intravenous urogram IVU (Plain x-ray + injected contrast)
- Ultrasound
- CT
- MRI
- Nuclear Medicine
Plain Film
First resort
Cheap + Uses radiation
1. Radio-opaque stones
2. Non-radio-opaque stones
3. Uric Acid
- Gout patients have uric acid filled/calcium absent stones –> suffer pain but cannot see stones (non-radio-opaque)
Note: Little stones cause biggest problems (enter ureter 5nm)
Pretest probability
Patient: Maori, male, gout, renal colic
= increased likelihood of uric acid stone
Plain x-ray wont help locate
Symptomatic differences b/w Appendicitis and Renal Colloid
Appendicitis: fever. Painful to breath –> dont want to move at all (burst peritoneum)
Renal Colloid: Ureters run down Transverse processes –> Loin-Groin pain (referred pain in testes)
- occurs in waves from high up –> extremely restless
- worst pain possible
Blood in urine
IVU
Intravenous Urogram
- plain x-ray + injected contrast
e. g. Blockage(tumour, stone, blood clot) –> Dye held in major calyces
Ultrasound
High frequency Sound waves
No radiation –> first tool for Children
Operator dependant (crisp picture with good technique)
- echogenic line (capsule), high echogenicity vessels
Patient body habitus dependant (Fatter –> decreased chance of sound waves travelling as far –> decreased clarity kidney)
Useful for:
1. Renal stones 2. Renal obstruction 3. Renal mass 4. Bladder lesions (cannot assess ureters)
Why cant a US assess ureters?
US ideal when water present
- air is deaf to Ultrasound
CT
More accurate Soft tissues assess, fluid, calcification Expensive significant radiation may need IV contrast dye Useful for: Stone (calculi), tumour, trauma, infection - Non light = Blockage - cancer in renal vein image*
MRI
Excellent Soft tissue evaluation and fluid Expensive No radiation, Use on someone who is comfortable;patient;doesnt wriggle;no traumatic experiences Longer scan time 30-45mins Useful for: 1. Soft tissue abnormality 2. Renal tumour 3. Infection Can have arteriogram w. MRI
Nuclear Medicine
Gamma camera + Radioisotopes (Inject Radioactive dye)
Functional Test: assess Function and Excretion of kidneys
Still involves radiation
Useful for obstruction
Renal imaging
- Antenatal (pre-birth)
- Pediatrics
- Adult
Differ by: - Clinical concerns (examination skills)
- Radiation issues (child/baby/teenager vs adult)
Note: need to do a discussion re balance of risks
- IF the benefits outweigh the theoretical risks, then tend to do it
Antenatal Renal imaging
- Congenital abnormality (agenesis, polycystic kidneys, multi-cystic dysplastic)
- Obstructed kidneys (PUJ, posterior urethral valve)
- Reflux
Note: all can be skilfully identified and treated if had correct clinical history and imaging
Antenatal Congenital abnormality: Agenesis (re. renal imaging)
No kidneys
- will survive until born
- due to circulation passing through placenta in womb
Therefore need to diagnose early
Clue: Baby tends to pee into amniotic fluid –> Decreased fluid
Antenatal Congenital abnormality: Polycystic Kidney (re. renal imaging)
abnormal kidney development –> decreased function
- sometime only effects one of the kidneys
Bilaterally enlarged echogenic kidneys (large and non-functioning)
Antenatal abnormality: Reflux (re. renal imaging)
Ureters enter at a steep angle
Contracting bladder should temporarily close the ureter to pee out front
Ureter at steep angle –> patient pees straight up –> “water hammer” back up into kidney –> kidney damage –> young teenagers with kidney damage –> Need transplant or Dialysis
Dilated and Thin cortex
dont know if is PUJ or reflux
more tests required
Antenatal Obstructed abnormality: PUJ (re. renal imaging)
Little boys w membrane b/w bladder and urethra in penis –> blocks outflow of bladder –> nothing can empty –> dribble urine
MCU
Micturating Cystourethrogam
- Vesico-ureteric reflux (watch baby pee)
Posterior Urethral valves
Posterior urethral valve (PUV) disorder is an obstructive developmental anomaly in the urethra and genitourinary system of male newborns. A posterior urethral valve is an obstructing membrane in the posterior male urethra as a result of abnormal in utero development.
Clinical scenario: Young 25 yr old man, left flank radiation to groin, haematuria, no fever, normal WCC
Likely to be Renal Colic
- cant see stone in x-ray
1. US : show kidney stone location and dilation
2. CT: coming down to groin + blood
Note: not one answer, depends on the clinical story
Renal Colic
12% of population will have urinary stone during lifetime (common)
Severe abdominal pain, radiating to gonad
“Writhing in pain” : difficulty lying still
Common stone location: narrowest part of ureter as entering base of bladder
Calculi
“stranding”: streaking of fat. epicentre of problem
- swollen and stranded kidney with non-moving stone
Peri-nephric stranding: around kidney
Peri-ureteric stranding: ureter
Hydronephrosis
Stone size and CT
Size of stone correlates with treatment
>6nm = 99% likelihood of eventual need for intervention = otherwise will just get infected (WONT PASS STONE)
-appears as swollen/fat ureter, almost holding the stone
Clinical scenario: 42 year old woman, right flank pain, fever, high WCC
Kidney Infection “pilonephritis” –> abscess puss
Diagnosis: US - local and targeted examination
- Puss: appears as grey speckles
- Abscess: mass hanging off kidney
Need to drain both puss and abscess
CT: could be tumour or abscess. But clinical story proves it isnt cancer
Clinical scenario: elderly 85 yr old man, recurrent urinary tract infection
Note: unusual for men to get urinary tract infection
1. US : enlarge prostate surrounding the bladder
- both kidneys markedly Dilated and Thin –> long term problem of decreased renal function
2. Catheter into enlarged prostate –> prostates squeezes around prostatic urethra –> obstructs outflow of bladder –> infect bladder
Symptoms:
a) peeing frequently
b) Artificial dehydration: tend to drink less after 3pm
Clinical scenario: 22 yr old woman, decreased renal function, high urea and creatinine
Polycystic kidneys –congenital/hereditary
- Slow penetrating gene: only occur sin 20’s maybe early 30s –> (potentially passed onto future generations)
- By now kidneys are no longer functioning well
- associated with cysts in liver and pancreas
1. US: non-obstructing cysts replace nephrons/glomeruli –> kidneys less able to function
2. Dialysis if full kidneys
Clinical Scenario: 25 year old man crashed his mountain bike in the forest
History: how he came off his bike, what hit what
Blood in urine? : shattered kidneys + soft tummy (kidneys are retroperitoneal, sit in own compartment)
Bleeding Retroperitoneal kidneys –> sit in own compartments shielded by fascia –> bleeding w/o blood appearing in abdomen –> Decreased BP, white, tachycardia
Treatment: LEAVE and support retro-peritoneal tamponade (be aware are dealing with a potentially dangerous situation)
CT: haematoma shows spilt renal artery/kidney. partially functioning. injury has gone through to liver OR kidney completely torn off –> no longer functioning at all
