KUB xray vs CT KUB for renal and ureteric colic

A 21 year old woman presented with vomiting and right flank pain. The pain started at 9am that morning, and had waves of 10/10 severity on a background of 8/10 severity. During a wave, she would be unable to get comfortable at all. Her urine dipstick was positive for blood (+++).

What imaging should be done next?

According to the 2012 iRefer guidelines from the Royal College of Radiologists, CT KUB should be done as the first line investigation, with KUB Xrays reserved for when neither CT nor IVU are indicated e.g. in pregnancy.

iRefer
iRefer

According to the 2012 British Association of Urological Surgeons, everyone gets a KUB Xray and then everyone gets a CT KUB. I do not understand the point of the double exposure, especially given that their own audit standard is CT KUB within 24 hours. What I found most interesting was that the BAUS referred to iRefer in their guidelines as the sole source that this imaging choice was based on.

Another standard I see people following is plain film KUB xrays all round, and only follow up with CT KUB if negative. Although this doesn’t help much with planning interventions, it used to ensure that everyone with stones gets diagnosed and hopefully with less radiation exposure than using CT KUB first line.

With the reduction in the doses used for CT KUBs recently, this may no longer be the case. An abdominal plain xray and a KUB plain xray both exposure the patient to 0.7mSv. To put this in perspective, a chest xray exposes the patient to 0.02mSv. Background radiation is about 2.2mSv in the UK per year. A diagnostic low dose CT KUB can be as low as 3mSv, and follow up with low dose CT KUB as low as 1.2mSv. I put some numbers together, and found that if you assume a sensitivity of 45% for plain film KUB, then if the CT KUB has a dose of 3mSv or lower and about 50% of the patients you investigate actually have stones, then going straight to CT KUB will reduce the total radiation dose compared to plain films followed by CT KUB if negative.

This does assume 100% sensitivity and sensitivity for the CT KUB, and 100% sensitivity for the plain film. I know that’s far from true, but it’s a rough idea of where things may eventually head if the CT KUB dose requirements keep reducing.

To muddy the water, the RCR did an audit looking at imaging done in acute renal colic. They said that CT KUB is the imaging of choice for both the BAUS and the iRefer guidelines, but did not specify whether or not it should be first line. Am I the only one who thinks these two guidelines do not quite agree with each other? And should we be going straight to CT KUB for all first presentation of ureteric stones?

NICE Guidelines for Cervical Spine Imaging 2014

There I was reading “Accident and Emergency Radiology” by Harvey and finding out how to interpret a cervical spine xrays when I discovered that the NICE guidelines on CT Imaging in Head Trauma had completely changed. For starters, it seems to imply that if anyone is good enough for the CT Head following traumatic brain injury, then they are also good enough for a cervical spine CT.

Who gets a cervical spine CT?

  • GCS < 13 on initial assessment.
  • The patient has been intubated.
  • Xrays are abnormal, unclear or inadequate – this could mean that the swimmer’s view will become a thing of the past, as it was done for making C7/T1 junctions more apparent when not well visualised. Now it seems you move straight to CT cervical spine.
  • A definitive diagnosis of cervical spine injury is needed urgently (for example, before surgery).
  • The patient is having other body areas scanned for head injury or multi-region trauma – ? all patients getting a CT Head for head injury

Also, if the patient is alert and stable, there is clinical suspicion of cervical spine injury and any of the following apply:

  1. age 65 years or older
  2. dangerous mechanism of injury (fall from a height of greater than 1 metre or 5 stairs; axial load to the head, for example, diving; high-speed motor vehicle collision; rollover motor accident; ejection from a motor vehicle; accident involving motorised recreational vehicles; bicycle collision)
  3. focal peripheral neurological deficit (including paraesthesia in the upper or lower limbs).

Those last three seem lifted straight from the Canadian C Spine rule.

Who can be cleared clinically?

People who don’t meet CT cervical spine criteria AND have at least one of the following:

  1. was involved in a simple rear-end motor vehicle collision
  2. is comfortable in a sitting position in the emergency department
  3. has been ambulatory at any time since injury
  4. has no midline cervical spine tenderness
  5. presents with delayed onset of neck pain.

According to NICE, if they can then actively rotate their neck 45 degrees to the left and right, that clears the C-spine.

What is the role of cervical xrays?

Those who don’t meet CT cervical spine criteria AND cannot be cleared clinically (either failing to be cleared clinically, or not having one of the 5 factors above that permit attempting to clear the c-spine clinically) should have 3 view C=spine xrays.

What’s this all based on?

It closely follows the Canadian C Spine rules:

C Spine
The C Spine rules from Canada

Myoclonus vs chorea

“Anyone can moonwalk. It’s making it smooth that matters” Michael Jackson never once said.

It’s all about smoothness when trying to decide between the dance like “there’s a snake trapped in my arm” chorea and the sudden involuntary contraction of myoclonus.

A boy in his mid teens presented with two years of shaking episodes, worse in the morning. He presented today as it had worsened over the past two days to the point when he could not open a bag of crisps without spilling half of them on the floor. These episodes could come in clusters, or on their own. It usually affected his hands more than his legs. He had occasionally fallen, where he went floppy and then twitched all over. He had never lost consciousness.  The symptoms were sometimes unilateral and at other times bilateral. He had no headache or visual symptoms. He had a normal development and academic ability. He had no family history of epilepsy or anything else of note.

He had a normal cranial nerve, upper limb and lower limb examination. I witnessed some of these abnormal movements. There were sudden, unprovoked contractions of his arm muscles, lasting less than a second. Sometimes two would occur in quick succession.

How could I convince myself it was not chorea? I had watched a few YouTube videos on chorea, and remembered this case in particular:

The chorea movements seemed to travel along a part of the body, and last more than a second at least. It was like a magician trying to distract you. Myoclonic jerks seemed more like someone had delivered a mild electric shock.

We felt there was too much staccato and not enough smooth for chorea. A provisional diagnosis of juvenile myoclonic epilepsy was made, and the patient referred to the first fit clinic.