Role of DIA in Diagnosing Nature of Indeterminate Biliary Duct Stricture

Biliary strictures (BSs) are common in clinical practice, but differentiating nature of the stricture either benign or malignant remains a challenge. Although there is a great advance in imaging and laboratory investigations, nature of BS is still unclear in some patients. Therefore, preoperative evaluation of such strictures is mandatory to put suitable plan with appropriate management.

BS is considered indeterminate biliary duct stricture (IBDS) if it has the following conditions; 1) no obvious mass on abdominal ultrasound (US), or magnetic resonance cholangiopancreatography (MRCP); 2) no distant metastasis on abdominal US, or MRI; and 3) no recent history of hepatobiliary surgery in the last 3 months.

IBDS has a particularly complex challenge, because patients and their physicians must weigh the malignant potential against benign etiologies in the face of morbidity of surgical intervention. About 15-24% of the patients had surgical intervention for suspected IBDS have a benign aetiology. Therefore, preoperative evaluation of such strictures is mandatory to put suitable plan with appropriate management.

Conventional cytological evaluation (CCE) has become the standard modality of practice for the investigation of such stricture. CCE had low diagnostic yield with an overall sensitivity of 41.6% and a negative predictive value of 58%. This low diagnostic yield is mainly attributed to desmoplastic reaction in BS.

Radiological elevation of BS with different modalities as MRCP enables us to detect the stricture and its extent and exclude other causes of obstruction. These modalities fail to determine nature of BS in many cases. In addition to, inability to take tissue sampling or perform therapeutic intervention.

Recently, there is a great advance in endoscopic assessment of BS as cholangioscopy, intraductal ultrasonography (IDUS), and confocal laser endomicroscopy. These techniques have high diagnostic yield in diagnosing nature of BS but secondary to high cost, complexity, and unavailability of these procedures, making them of limited use in evaluation the nature of IBDS.

Advanced cytological techniques have been emerged to identify nature of IBDS i.e., digital image analysis (DIA), and fluorescence in-situ hybridization (FISH) where both techniques detect the chromosomal alterations in malignant cells.

FISH is significantly more sensitive than CCE for assessment the nature of IBDS. However, the specificity of FISH was poor compared to the excellent specificity of CCE. The compromised specificity of FISH may limit its utility in the detection of nature of IBDS.

DIA has been widely used in many malignant diseases, especially in cervical cancer where it had 70% to 91.7%, sensitivity and 54.1% to 100% specificity for the diagnosis of different malignant diseases in published studies.

Role of DIA in pancreatobiliary malignancies is still controversial. Also, there are limited studies that have addressed the use of DIA in diagnosing the nature of IBDS. In addition to unavailability, the high cost and the complexity of advanced endoscopes, we designed this work to evaluate the diagnostic performance of DIA in identification nature of IBDS in comparison to CCE. Also, we perform a cost analysis of DIA vs. CCE in diagnosing nature of IBDS.