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Three Part Question

In [adult patients with minor blunt thoracic trauma] is [ultrasound more sensitive than chest x-ray] at [detecting rib fractures]?

Clinical Scenario

A 40-year-old patient attends the emergency department having fallen down some five stairs. During evaluation, he reports pain over his left chest and tenderness is found on palpating of his ribs in this area. You consider sending him for a chest x-ray to diagnose fractured ribs but are advised against this by a senior colleague who says it is insensitive. You wonder if ultrasound is more sensitive than x-ray in detecting rib fractures.

Search Strategy

Ovid MEDLINE(R) 1946 to November Week 2 2013: exp Rib Fractures/di, ra, us [Diagnosis, Radiography, Ultrasonography] LIMIT to humans (‘all adult (19 plus years)’ or ‘adolescent (13 to 18 years)’) (english or french) yr=‘2012–2013’

OVID Embase 1980-January.2013: Exp rib fracture/ OR rib fracture.mp. OR ultraso$.mp. OR echograph$.mp. OR sonograph$.mp.

The Cochrane Library Issue 11 of 12, November 2013: MeSH descriptor: [Rib Fractures] explode all trees and with qualifiers: [Ultrasonography - US] 0 records.

Search Outcome

Five articles were found that were relevant to the question. Of these, three papers were descriptive studies without sensitivity calculation and were, for this reason, excluded. The two remaining articles are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Griffith et al, 1999, China	50 patients aged between 24 and 89 years Time between trauma and enrolment: 1–21 days (mean 3.5 days) x-Ray performed on the day of the emergency evaluation and read by two independent radiologists; US performed within 3 days of the ED presentation in the radiology department USS vs x-ray	Prospective cohort study, diagnosis	Sensitivity	90% vs 15%	Study conducted in one single centre. Small study population. The inclusion of some patients at 3 weeks post-trauma: certainly affects sensitivity (bone callus). No universal gold standard: authors used US as its own gold standard 3 weeks after the initial US. 26% (13 patients) lost to follow-up: no worst case scenario suggested by the authors. Sensitivity/specificity formulas obscure
Rainer et al, 2004, China	88 patients: 10 years old minimum age Unknown time between trauma and enrolment; x-ray performed on the day of the evaluation and read by two emergency physicians. US performed within 24 h of ED presentation and read by radiologist USS vs x-ray	Prospective cohort study, diagnosis	Sensitivity at identifying rib fracture	80.3% vs 23.7%	Study conducted in one single centre. Small study population. Unknown time between trauma and enrolment: certainly affects sensitivity (bone callus). Reference standard bias: no universal gold standard (authors used US as its own gold standard 3 weeks after the initial US). US performed by a radiologist

Comment(s)

In one study (Rainer and colleagues), the ultrasound was performed and read by a radiologist. In the study by Griffith and colleagues, it is not known what skills the ultrasound executor had and who read the images, which makes comparison difficult. In both included studies, there was no universal gold standard. The authors of both studies used ultrasound as its own gold standard, which brings major concern about the validity of sensitivity values.

Editor Comment

ED, emergency department; US, ultrasound.

Clinical Bottom Line

While current studies suggest ultrasonography is better than x-ray at detecting rib fractures, further studies with a well-established gold standard should be completed before ultrasonography is used routinely.

References

1. Griffith JF, Rainer TH, Ching AS, et al. Sonography compared with radiography in revealing acute rib fracture. Am J Roent 1999:173;1603–9.
2. Rainer TH, Griffith JF, Lam E, et al. Comparison of thoracic ultrasound, clinical acumen, and radiography in patients with minor chest injury. J Trauma 2004:56;1211–13.