In radiology, the Rules of Two (Ro2) is a helpful, simple set of guidelines that help to ensure no fractures or other damage is missed on an X-ray. It’s an important way of giving patients (and radiologists) reassurance that any breaks are diagnosed correctly and in full the first time.
So what are the “Rules of Two”
Some part of the Ro2 are fairly obvious, but others are more nuanced. The principles can be generally applied across the board, but some relate to specific clinical problems.
Not only can the Rules of Two help to identify broken bones accurately, they also help plan the patient’s management and care.
The Rules of Two are:
- Two views – one view is always one view too few
- Two abnormalities – if you see one abnormality, automatically check for a second
- Two joints – image the joint above
- Two sides – if not sure or the X-ray is difficult, compare with other side
- Two occasions – always compare with old films IF available
- Two visits – bring the patient back for repeat examination
- Two opinions and two records – always ask a colleague if you’re not sure and record findings
- Two specialists – always get a specialist opinion
- Two investigations – always consider whether US, CT or MRI would help in diagnosis
Rule 1: Two views (‘One view is always one view too few’)
Two X-ray views should be taken, perpendicular to each other preferably. This should always be the case when X-raying any part of the body, except the chest, pelvis and abdomen. It is not uncommon for a fracture or an abnormality to only show up on one view.
Furthermore, if a broken bone is strongly suspected but the two views fail to show an injury, additional clinical investigation will be required.
Rule 2: Two abnormalities
Even once one abnormality has been detected, don’t assume there aren’t more – keep looking. Not only may there be another fracture, there may also be an underlying predisposing abnormality, such as metastases. Additionally, if there is a fracture in a ring-like structure such as the mandible, pelvis, radius/ulna or tibia/fibula, there will typically be a second fracture (a polo mint will always break in two places).
Are you a healthcare professional who wants to to learn more about X-ray interpretation and fracture diagnosis?
If so, why not sign up for PDUK’s online course: X-ray interpretation of minor injuries – includes Red Dot.
Ideal for nurses, ENPs, medical students and other allied healthcare professionals, it’s a one-day course worth 7 hours of CPD. Held entirely online, it’s ideal for anyone who wants to learn remotely whilst still getting the benefits of networking and socialising.
Note: Practitioners should ideally be working in an environment where X-ray interpretation is part of their role but it may be suitable for practitioners making referrals for X-rays at another location. Some experience with x-ray interpretation is required. Clinical areas include minor injury units, A&E departments, out of hour’s services and walk-in centres.
All course material, evaluations and a certificate of attendance are provided. However, numbers are always limited (and this one’s popular!) so book your place today.
