Table 2:
Imaging modalities for detecting stones in the common bile duct4
| Imaging modality | Description | Advantages | Limitations |
|---|---|---|---|
| Transabdominal ultrasonography | Noninvasive procedure whereby high-frequency sound waves are converted into images | First-line imaging modality, noninvasive, widely available and inexpensive Sensitivity 22%–65%* Specificity 70%–98%* |
Artifacts may be caused by pneumobilia, surgical clips, biliary stents, duodenal diverticula, and calcifying pancreatitis |
| Endoscopic ultrasonography | Use of a duodenoscope with an ultrasound transducer at its tip; images are more accurate and detailed than ones obtained by traditional ultrasonography because of the proximity of the transducer to the organs of interest | More cost-effective than ERCP as a diagnostic tool Sensitivity 85%–97%* Specificity 90%–95%* |
Not widely available; operator dependent; artifacts may be caused by pneumobilia, surgical clips, biliary stents, duodenal diverticula and calcifying pancreatitis |
| Intraductal ultrasonography | Imaging of the biliary tree with an ultrasound transducer mounted at the tip of a catheter inserted through duodenoscope | Sensitivity 97%–100%* | Probes have limited durability; stones, sludge and air bubbles may be indistinguishable |
| Laparoscopic intraoperative ultrasonography | Intraoperative use of a specialized laparoscopic probe with an ultrasound transducer at the tip that is positioned to visualize the biliary system | Sensitivity 80%–83%* Specificity 99%–100%* |
Technically difficult to perform, especially in obese individuals; operator dependent; suboptimal visualization of the intrapancreatic portion of the common bile duct; artifacts may be caused by pneumobilia; detects sludge and small stones that are of limited clinical significance |
| ERCP | Injection of a contrast agent directly into the common bile duct and imaging at duodenoscopy; considered the “gold standard” against which other imaging modalities are compared | Sensitivity 89%–90%* Specificity 98%–100%* |
Operator dependent; overall complication rate 4%–6%; mortality associated with procedure 0.1%–0.5% |
| Intraoperative cholangiography | Insertion of a catheter through the cystic duct at the time of surgery, followed by injection of a contrast agent into the common bile duct and fluoroscopic imaging | Sensitivity 75%–100%* Specificity 97%–100%* |
Prolongs the duration of the surgical procedure; fluoroscopy use in the operating room |
| Helical computed tomography cholangiography | Computed tomography of the biliary system following intravenous administration of a contrast agent | Sensitivity 71%–85%* Specificity 88%–97%* |
Similar drawbacks to those with intravenous cholangiography |
| Intravenous cholangiography | Injection of a contrast agent intravenously, followed by radiographic imaging of the biliary system | Relatively noninvasive; provides information on the biliary ductal system Sensitivity 48%–50%* Specificity 95%–97%* |
Risk of reaction to contrast agent (1%) or renal impairment; limited value in patients with elevated bilirubin level because of decreased excretion of dye into the biliary system |
| Magnetic resonance cholangiopancreatography | Magnetic resonance imaging whereby the hepatobiliary and pancreatic system are visualized using a specialized sequence | Can be used when endoscopic ultrasonography and ERCP is not possible (e.g., after Rouxen-Y gastric or biliary procedures); diagnostic accuracy decreased if stones < 5 mm or common bile duct > 10 mm Sensitivity 85%–100%* Specificity 91%–97%* |
Hard for patients with claustrophobia to tolerate; may cause dysfunction of certain pacemakers or implantable cardiac defibrillators, or dislodgement of metallic prostheses |
ERCP = endoscopic retrograde cholangiopancreatography.
*
Using different reference standards across multiple studies. See Appendix 2 (available at www.cmaj.ca/lookup/suppl/doi:10.1503/cmaj.110896/-/DC1) for citations of included studies.