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Letters to the Editor |
and
Raffaele Iorio, MD *
* Department of Pediatrics, University Federico II, Via Pansini 5, 80131 Naples, Italy
e-mail: riorio{at}unina.it
Department of Biomorphological and Functional Sciences, University Federico II, Via Pansini 5, 80131 Naples, Italy
In the September 2007 issue of Radiology, Drs Humphrey and Stringer (1) emphasized the high sensitivity and specificity of some ultrasonographic (US) features such as triangular cord sign and abnormal gallbladder wall and shape for the diagnosis of biliary atresia (BA). The authors reported that US is reliable in differentiating BA from other causes of cholestasis (1). In contrast with these enthusiastic data, the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) guidelines recommend that US of the liver and biliary tree cannot be used to rule out BA, and percutaneous liver biopsy is considered to have the greatest diagnostic accuracy and best reliability in differentiating BA from other conditions (2). US is considered useful for the initial evaluation in the infant with cholestasis of unknown cause, but liver biopsy and laparotomy remain mandatory if BA is suspected. Furthermore, US presents many pitfalls, such as detection of a small nondistended gallbladder (suggesting BA) in case of severe intrahepatic cholestasis; detection of a clear fluid-filled gallbladder remnant, indistinguishable from normal findings, in some patients with BA; and also difficulty in visualizing common bile ducts in healthy infants (3). On the basis of these considerations, we think that US cannot be used as a single diagnostic tool in the evaluation of infants with cholestasis. In our experience, 17 of 25 infants with BA confirmed at liver biopsy and intraoperative cholangiography had an identifiable gallbladder at US, with a regular shape in one-fifth of cases, and triangular cord was identified in only six patients.
While this lower sensitivity of US might be operator or machine dependent, the crucial point is not the level of sensitivity of US in detecting signs of BA but its reliability as a single diagnostic tool that may avoid the use of invasive procedures. In conclusion, we are concerned that the interesting study by Drs Humphrey and Stringer may raise excessive enthusiasm and indirectly compromise a prompt and accurate diagnosis in many clinical cases, in that diagnosis of BA remains an urgent matter for which no single diagnostic procedure appears to be clearly superior.
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* Department of Radiology, St James's University Hospital, Beckett Street, Leeds LS9 7TF, England e-mail: teresa.humphrey{at}leedsth.nhs.uk
Children's Liver & GI Unit, St James's University Hospital, Beckett Street, Leeds LS9 7TF, England
Dr Giannattasio and colleagues raise several concerns about the US diagnosis of BA with which we strongly disagree:
1. The evidence-based NASPGHAN guidelines (published in 2004) to which they refer concluded that 50%–99% of cases of BA are correctly identified at percutaneous liver biopsy and that BA is incorrectly suspected from the biopsy findings in 0%–46% of cases. The guidelines recommended that liver biopsy is performed in most infants with undiagnosed cholestasis but, if performed before 6 weeks of age, it may have to be repeated if the results are equivocal. Guidelines must be updated in the light of new evidence. Findings of several studies published in the last few years attest to the increasing accuracy of US in the diagnosis of BA.
2. "[L]aparotomy remain[s] mandatory if BA is suspected." While BA must be confirmed at laparotomy, improving preoperative diagnosis should help some infants avoid unnecessary surgery.
3. We agree that US diagnosis has potential pitfalls (as do all techniques for the preoperative diagnosis of BA), but our results speak for themselves.
4. Nowhere did we state that US can be used as "a single diagnostic tool in the evaluation of infants with cholestasis". The concluding paragraph of our article states that infants with no US evidence of BA require further investigation to establish the cause of their conjugated hyperbilirubinemia.
US is both operator and experience dependent. The clearly stated purpose of our prospective study was to show what can be achieved by a dedicated sonographer by using multiple US criteria in a specialist pediatric liver center with a relatively high throughput of infants with jaundice. The retrospective results quoted from Naples give no indication of the number or experience of sonographers involved, the period of time over which the imaging was performed, and the volume of patients with neonatal conjugated hyperbilirubinemia being assessed annually.
The challenge in US diagnosis of BA is to encourage units to develop similar expertise to ours rather than continue with the nihilistic view, reinforced by disappointing local experience, that no single diagnostic technique is superior.
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