Dr David McCreary Emergency Physician
Pelvic fractures are pretty common, particularly if you work in a trauma centre. From a trauma resuscitation perspective, we're usually most concerned with whether a pelvic injury is unstable with disruption of the pelvic ring, and if there is active arterial bleeding. When our patients are haemodynamically behaving themselves, and don't have active bleeding we can take a breath and relax and think about, amongst other things, getting a urinary catheter in the patient...and that's when we should be thinking about a retrograde urethrogram (RUG). This came up in a few discussions in our Grand Rounds sessions last year, so I thought it would be useful to do a quick refresher on the technique.
🤨 Just here to refresh on the technique? Click here, I've got you covered. 😉
WHY IS IT IMPORTANT?
Urethral injury is a common complication, up to 24%, of pelvic fractures
Bad if missed (just ask a urologist - they hate managing urethral strictures)
Can be made worse with insertion of a urinary catheter (partial tear = bad. Poking at it can cause it to become a complete transection = very bad)
WHO SHOULD GET IT?
Firstly, men. 97% of urethral injuries occur in male patients(1); the shorter female urethra is less prone to shearing stresses. If you think there are signs of urethral injury in a female patient (approx. 80% are associated with vaginal laceration or blood at the introitus(2)) – skip the RUG and get the urologists involved.
Back to the blokes, if you remember back to your ATLS/EMST course they quote:
Gross haematuria
Inability to void
Unstable pelvic fractures (particularly with symphysis diastasis(1), straddle fractures and Malgaigne fractures)
Blood at the urethral meatus
Scrotal haematoma
Perineal ecchymoses
High-riding prostate
Any of the above and you should be checking out that urethra.
Now, I remember quoting the above list in my first ATLS course (In 2009? Oh my.), but as a fresh-faced PGY-2 I’ll admit thinking of it as some difficult, fancy imaging technique that I would need to beg some clever radiologist to perform, I had no idea that it was actually pretty easy and could be done in a trauma bay using the overhead X-Ray.
ANATOMY
Before looking at the technique, it’s worth having a refresh on the anatomy, just so we know what we’re looking for.
The male urethra has 4 Parts:
Anteriorly:
Penile
Bulbous
Posteriorly: (Most common injury - up to 25% of pelvic fractures)
Membranous
Prostatic
OK, SO HOW DO I DO IT?
Technique:
Get some (water soluble) contrast media from radiology
Place the patient in 25–30-degree oblique position
Having a pelvic fracture patient in an oblique position is a challenge – the fluoroscopy / X-Ray can be aimed from an oblique position, with the penis positioned appropriately to allow visualisation of the entire urethra
Insert Foley catheter 2-3cm into meatus and inflate the balloon with 2-3ml of water, stretch the penis to straighten the urethra, hold catheter in place.
Inject 20-30ml of undiluted, sterile, water soluble contrast
Take X-ray image every 10 mls
Be careful not to spill – it’ll mess up your images and give false positives or unequivocal tests
If images show intact urethra:
Deflate balloon
Advance Foley into bladder and inflate balloon with 10ml water
If images show injury, or equivocal or if advancement of foley causes pain or resistance is met – stop advancing and chat to your friendly neighbourhood pee-pee surgeon
WHAT WOULD ABNORMAL FINDINGS LOOK LIKE?
Intravasation of contrast
Urethral occlusion (failure of dye to enter the bladder)
But what does that actually look like?
FIRST, A NORMAL TEST TO GET YOUR SIGHTS IN
(Case courtesy of Dr Mohammad Taghi Niknejad, Radiopaedia.org, rID: 61843)
NOW, AN ABNORMAL TEST
Note the venous intravasation of contrast that has escaped through a urethral defect.
(Case courtesy of Dr Mohammad Taghi Niknejad, Radiopaedia.org, rID: 61843)
INJURY CLASSIFICATION
Now for sprinkles on top of our required knowledge, urethral injuries can be classified by a couple of systems: the AAST and the Goldman Classification. For our purposes the AAST is more straightforward, but Goldman as apparently more widely accepted, so I’ll include them both.
AAST System
THE GOLDMAN SYSTEM
(My super-mature way to remember the name is that urine is, or at least should be, golden and we’re doing this test in men):
WHY DOES CLASSIFICATION MATTER?
Grade I: May be conservatively managed.
Grades II-V: usually result in severe stricture and so urology may take for immediate surgery
TAKE HOMES?
Consider urethral injury with pelvic fracture, particularly if you have symphysis diastasis
Have a really low threshold to do RUG
It's really a lot easier than you think
If in doubt on results, or if your patient is female, get a urology opinion
REFERENCES / FURTHER READING
Lückhoff C, Mitra B, Cameron PA, Fitzgerald M, Royce P. The diagnosis of acute urethral trauma. Injury. 2011 Sep;42(9):913–6. DOI: 10.1016/j.injury.2010.08.007 PMID: 20739022
The Royal Melbourne Hospital guideline is great, with some useful flow charts.
This review is where I got a lot of this from and has some great learning points (Ingram MD, Watson SG, Skippage PL, Patel U. Urethral Injuries after Pelvic Trauma: Evaluation with Urethrography. RadioGraphics. 2008 Oct;28(6):1631–43.)
Radiopaedia, as always have a nice summary with some more pictures
A comprehensive, if a little dull, video summary on youtube
DAVID MCCREARY
Emergency Physician
Dave is an Emergency Physician, one of the Alfred's Directors of EM training, and the creator of this education blog. He trained between the UK and Australia and completed an MSc in Trauma Science with QMUL. His clinical interests include trauma, critical care, evidence based medicine and human factors. Dave is a regular contributor the RCEMLearning podcast and is a FOAMed editor for RCEMLearning. He dislikes coriander, decaff coffee and dermatology.
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