Rib fractures: elusive, but important
Authors: Kenneth W Feldman
Journal: The Lancet Child & Adolescent Health (2018)

Physical abuse of children is all too common, but often difficult to detect. Although we as physicians usually trust caretaker histories, with cases of abuse those histories are often partial, minimised, or intended to misdirect clinical evaluations. Thus, we usually depend on patterns of physical findings and injuries that are inconsistent with offered histories. In those evaluations, one important and recommended tool is skeletal imaging of children aged 1–3 years for whom concerns of physical abuse exist. This skeletal imaging has usually involved skeletal surveys (ie, radiography). After skull fractures, rib fractures are the most common skeletal injury in abused infants,1Kleinman PK Skeletal trauma: general considerations.in: Kleinman PK Diagnostic imaging of child abuse. 3rd edn. Cambridge University Press, Cambridge2013: 23-52Google Scholar but they can be difficult to see and confirm on an initial skeletal survey. As a result, oblique view radiographs and follow-up skeletal surveys for rib healing are now recommended.2Flaherty EG Perez-Rossello JM Levine MA et al.Evaluating children with fractures for child physical abuse.Pediatrics. 2014; 133: e477-e489Crossref PubMed Scopus (196) Google Scholar However, neither of these follow-up measures provide immediate evidence that can help decide whether the child needs protection during the period between first evaluation and follow-up scans. Several attempts have been made to improve sensitivity and specificity for the detection of rib fractures by use of chest CT during the acute injury evaluation. Post-mortem CT is also being adopted in some autopsy protocols for sudden unexplained death in infanty (SUDI). In The Lancet Child & Adolescent Health, Susan Cheng Shelmerdine and colleagues3Shelmerdine SC Langan D Hutchinson JC et al.Chest radiographs versus CT for the detection of rib fractures in children (DRIFT): a diagnostic accuracy observational study.Lancet Child Adolesc Health. 2018; (published online Sept 21.)http://dx.doi.org/10.1016/S2352-4642(18)30274-8Scopus (26) Google Scholar report a well designed study comparing post-mortem skeletal survey images and CT images, with autopsy as the gold standard reference. They searched the Great Ormond Street Hospital radiology database between Jan 1, 2012, and Jan 1, 2017, for patients aged 0–16 years who had a post-mortem skeletal survey, whole-body CT, and autopsy, and for whom a forensic investigation had been completed. Of the 25 cases selected for analysis, 17 had fractures and eight did not, as confirmed by the autopsy results. They recruited radiologists of varied experience from several international radiology societies to analyse the radiographs and CT images, and asked them to identify if a rib fracture was present, and the rib, rib location, and number of fractures, as well as their confidence in their decision. Among the 17 children with fractures, 136 fractures were identified by autopsy, with a median of seven (range 1–20) fractures per child. 111 (82%) fractures were anterior, ten (7%) were lateral, and 15 (11%) were posterior. Shelmerdine and colleagues found that CT was much more sensitive than radiography for the correct identification of the location of the rib fractures (44·9% [95% CI 31·7–58·9] vs 13·5% [8·1–21·5]). CT was also better than radiography for determining whether any rib fractures were present (sensitivity 81·5% [95% CI 75·8–86·0] vs 64·7% [57·3–71·4]), but specificity of this determination was only around 50% for both methods; although they found radiography was only 27·3% (95% CI 14·5–47·0) sensitive for posterior rib fractures, whereas CT was 60·2% (40·3–78·0). In diagnostic judgments as substantial as abuse, high specificity in the identification of a rib fracture is very important. Shelmerdine and colleagues estimated that for every 6·0 (95% CI 4·5–8·7) children identified as having a rib fracture or fractures by use of chest radiography, one additional child would be identified by use of CT. The authors provided details about the autopsy diagnoses compared with the presence of rib fractures. Of the patients with rib fractures, six were suspected as having been abused, with causes of death including trauma and asphyxia. Of those for whom abuse was unlikely to have caused the rib fractures, five had otherwise undiagnosed SUDI, one had traumatic brain injury for which the cause was unclear, one had both traumatic brain injury and sepsis, and one had an unascertained cause of death. A further three patients with fractured ribs had deaths that would be considered as less likely to be caused by abuse: one child had sepsis alone, one had small bowel volvulus, and one had a congenital vitamin D deficiency. Since the authors did not use the CT images to direct the rib examination during autopsy, the false positives on analysis of the images could be rib fractures that were missed at autopsy, yielding higher imaging specificity. We are in the process of doing a study of post-mortem whole-body CT as a part of forensic autopsies for SUDI. Many rib fractures we have found would not have been detected without CT-directed rib excision and histology. Because a diagnosis of abuse relies on a combination of unlikely and inconsistent injuries, the more of such injuries that are are identified, the greater the diagnostic certainty of abuse is. Rib fractures often accompany abusive head injury. The probability of abuse in children with intracranial injury and retinal haemorrhage alone is about 33%, but this probability increases to about 98% by addition of rib fractures.4Maguire SA Kemp AM Lumb RC Farewell DM Estimating the probability of abusive head trauma: a pooled analysis.Pediatrics. 2011; 128: e550-e564PubMed Google Scholar Rib fractures alone in infants aged 0–48 months without major recognised trauma have a 66% positive predictive value for abuse.5Maguire S Cowley L Mann M Kemp A What does the recent literature add to the identification and investigation of fractures in child abuse: an overview of review updates 2005–2013.Evid Based Child Health. 2013; 8: 2044-2057Crossref Scopus (43) Google Scholar Conclusions of studies have differed regarding whether posterior rib fractures are more likely to have resulted from abuse;6Kemp AM Dunstan F Harrison S et al.Patterns of skeletal fractures in child abuse: systematic review.BMJ. 2008; 337: a1518Crossref PubMed Scopus (332) Google Scholar this study suggests that CT might be superior for their identification and so could help to determine if this hypothesis is correct. This study was done using high-dose post-mortem imaging, thus extrapolation of the authors' results to live children and normal imaging practices should be done with caution. The relatively high-dose of conventional chest CT has been a barrier to use in live children. However, a small case series7Sanchez TR Lee JS Coulter KP Seibert JA Stein-Wexler R CT of the chest in suspected child abuse using submillisievert radiation dose.Pediatr Radiol. 2015; 45: 1072-1076Crossref PubMed Scopus (19) Google Scholar suggests the superiority of very low dose chest CT (0·56 mSv) over conventional four-view chest radiographic films (0·29 mSv) with little additional radiation. This case series and the current autopsy study suggest that an expanding role for chest CT in live and post-mortem child abuse investigations might be appropriate, but only with the careful addition of further studies. I provide legal consultation in child abuse cases. Chest radiographs versus CT for the detection of rib fractures in children (DRIFT): a diagnostic accuracy observational studyChest CT provides greater accuracy than conventional chest radiography for post-mortem rib fracture detection, irrespective of radiologist experience or fracture location, although both methods detected a substantial number of false positives. The diagnostic accuracy of CT should be studied further in live children ideally in a multicentre trial to assess the applicability of our results. Full-Text PDF Open Access