Of the 244 children with likely abusive injuries in our study, 51 (21%) were screened for OAT, and 21 had one or more positive screening tests for OAT. This represents 41% of all children screened and at least 9% of all children with abusive injuries. These are conservative estimates assuming that no OAT was present among those children who were not screened. Our rate of 9% is similar to findings in other studies. For example, Coant found positive screens in 8% of children with suspected child abuse, and Isaacman examined children with non-inflicted trauma and found occult abdominal injury in 6%.3,15
OAT is therefore hardly rare in the context of possible physical abuse.
When examining the rate of occult injury confirmed by abdominal CT or ultrasound, we found that 10% of children screened had OAT, accounting for 2% of all children with physical abuse and 5% of toddlers. These rates are comparable to those of other studies of children with both inflicted (6%) and non-inflicted (4.8%) trauma.3,15
Our findings indicate that at a minimum, 2 of every 100 children under 5 years of age presenting with possibly abusive injuries also have occult abdominal injury, and 1 in 20 toddlers may have occult abdominal injury.
For a number of reasons, our rates of occult abdominal trauma can only be considered estimates. First, our data and that of other researchers suggest that abdominal ultrasound and CT are not true gold standards, and may miss some abdominal injuries. Even if the radiologic testing were considered the gold standard, the majority of children did not have ultrasound or abdominal CT performed. Therefore, the sensitivity and specificity of the laboratory tests could not be determined. Further, some of the children with abnormal screening tests did not have radiologic testing; therefore, we were unable to confirm the presence of abdominal injury. While most children in this group had only mildly elevated laboratory results, this does not eliminate the possibility of abdominal injury. The utility of both screening and diagnostic tests varied according to the abdominal organ of interest, as discussed below.
While several authors have found liver transaminases to be an accurate predictor of hepatic injury,15–18
with sensitivity of 93–100%, and specificity of 53–100%, a more recent publication indicated a much lower sensitivity of only 53%.19
Although we could not calculate sensitivity or specificity, we did find these screening tests to have reasonable predictive value. Our positive predictive value of 60–80% is higher than that of 43% in Isaacman’s study.15
While we did not find any obvious liver lacerations, findings such as ascites surrounding the liver, and coarse echogenicity of the liver are strongly suggestive of trauma, particularly in the context of elevated transaminases.20
Our high positive predictive value supports the recommendation to perform screening in children being evaluated for suspected physical abuse.
While three children had markedly elevated pancreatic enzymes, and all had CT or ultrasound performed, we did not find any obvious pancreatic lacerations. This finding might be construed as pancreatic enzymes not being predictive of pancreatic injury. However, other studies indicate that identification of pancreatic trauma by CT may be particularly difficult.21–23
Therefore, it is likely that some pancreatic injuries were present despite negative CT scans. This finding suggests that our estimates of OAT may be higher than our conservative estimate of 2% noted above.
We had hoped that stool Hemoccult would adequately screen for intestinal injury. Unfortunately, testing was only performed in two children, making it impossible to assess its utility. Given the possibility of bowel trauma, it seems prudent to perform this easy screen although its sensitivity in other studies ranged only from 25–60%.24,25
Results from several previous studies indicated that hematuria might also be an accurate predictor of renal injury.15,26–28
Unfortunately, the three children identified with hematuria did not have radiologic testing to evaluate for possible renal or bladder injury. Optimal practice should include further evaluation. Given the ease and low cost of these two tests, it appears reasonable to include them in screening children with suspected physical abuse.
Several children in our study had traumatic injuries such as a lung contusion and splenic trauma that could not have been identified through any specific screening test. These findings indicate that many children with abusive injuries may also have occult injuries that cannot be identified through non-invasive screening tests. The decision to search for such occult injury must therefore balance the risks of missing an injury, (e.g. bleeding, sepsis, death, return to an abusive caregiver) with the risks of radiation, sedation, and oral contrast required for abdominal CT, as well as the cost of CT or ultrasound.
We did not identify disparities in OAT screening by race, gender or insurance status, findings that were reassuring given previous studies demonstrating differential screening for abusive head trauma and occult skeletal injury by race,29, 30
and differences in diagnosis of abuse by social class.31
However, limited racial and socioeconomic variability in our sample made it difficult to examine differences.
We expected rates of screening to be higher for more severe injuries such as fractures and abusive head trauma. This was the case for the most part in our bivariate analyses. However, only abusive head trauma remained a predictor of screening in our multivariate analysis. It is likely that physicians considered abusive head trauma to be a more severe form of abuse than the other abusive injuries.
Subspecialty input clearly played a role in the decision to perform OAT screening. This may have reflected the severity of children’s injuries; children with more severe injuries were more likely to have subspecialty and CPT consultation, and were more likely to be screened because of the severity of injury. However, it may also be because subspecialists were more aware of the possibility of occult abdominal injury compared to the emergency department physicians.
Screening occurred less often during peak ED hours (4–11 p.m.). This finding suggests that physicians screen more often when they have more time to think about patient evaluation and management, and forget to screen when they are busy. Development of management pathways or computerized order templates could prompt physicians to screen when they might otherwise forget.
There were a number of limitations to this study. As it was a retrospective chart review, we could not guarantee that children would be screened for OAT, nor that children with positive screens would have a CT or ultrasound performed. Therefore, it is probable that some children with OAT were missed. This was a particular problem for the 3 children with hematuria who did not have abdominal imaging, as several studies have shown that hematuria is a good marker for intra-abdominal trauma among children with non-inflicted injury.15,26–28
We have therefore presented conservative estimates of the percentage of positive screens, assuming that none of the unscreened children had OAT, and noting the minimum percentage of children with OAT. Even with these conservative estimates, the proportion of physically abused children with OAT is high enough to warrant screening, at least for children under 3 years of age.
A second limitation was the small number of children with positive OAT screens and/or findings on abdominal CT or ultrasound. The low numbers precluded identifying factors associated with the presence of occult abdominal injury. Future prospective studies may better identify these factors, and provide more specific criteria for OAT screening.
The abdominal injuries in our study were not associated with significant morbidity. However, the presence of multiple injuries is potentially a marker for more serious abuse, with important implications for children’s health and safety.