| Suspect Biliary Colic – Imaging Strategy
Author: Charles Allison, MB ChB Editor Ashley Davidoff MD copyright 2006 CLINICAL BACKGROUND – The “classical ” presentation of biliary colic is characterised by intermittant RUQ pain that lasts for 1-6 hours with intermittant colicky components when the intensity of the pain increases. Precipitaing factors include a recent ingestion of a meal.. The pain may radiate to the right scapula or shoulder. Associated symptoms may include nausea and vomiting, but unless the disease is complicated by cholangitis there is no associated fever. While the wcc is usually normal the bilirubin and alakaline phosphatase are usually slightly elevated. IMAGING STRATEGIES WHAT STUDY? Ultrasound is the investigation of choice in this patient with suspected biliary colic. US is highly sensitive for cholelithiasis (95-98%) , and bile duct dilatation but is less sensitive in identifying choledocholithiasis (40-60%). Findings of gallstones in the common bile duct would confirm the diagnosis, Dilation of the common bile duct may indicate recent passage of gallstones. A normal US with normal biliarychemistries hs a negative predictive value of 95%. Endoscopic US is higly sensitive to choledocholithiasis as is MRCP. WHY? Ultrasound provides a non-invasive and low cost method for establishing the presence of gallstones. Stones in the distal CBD may be missed in larger patients. MRCP (Magnetic Resonance CholangioPancreatography) is also a good choice of investigation with higher resolution and less operator dependence, but is more expensive. Typically if the ultrasound confirms the diagnosis, or if there is a very high clinical suspicion in the absence of positive ultrasound findings, ERCP (Endoscopic Retrograde CholangioPancreatography) is performed in preference to MRCP as it allows similar bile duct imaging with the added benefit of therapeutic options (sphincterotomy or stone retrieval). BACKGROUND TO THE DISEASE: Gallstone disease affects 10-20% of the population, though the majority are asymptomatic incidental findings. Classically occur in fair, fat, fertile females in their forties – fifties. Most gallstones are predominantly cholesterol (80%, often solitary if solely cholesterol), but may also be pigmented (formed from bile with less than 25% cholesterol content, usually multiple and irregular) or mixed (faceted appearance, calcium containing). Biliary colic occurs when gallstones pass out of the gallbladder and pass through the cystic duct and common bile duct to reach the duodenum. The passage of the stone typically takes from 1-3 hours. Treatment involves pain control and cholecystectomy. It is differentiated from biliary colic mainly by the absence of inflammation. Complications included cholangitis, acute pancreatitis and gallstone ileus. WHEN? Acute abdominal pain requires urgent care and the patient should be imaged urgently on the day of presentation. After the appropriate bloods are drawn ultrasound should be performed while the possibility of finding the stones in the duct exists. Patients without acute symptoms can have an elective ultrasound to identify evidence of bile duct dilatation. HOW TO ORDER? When ordering an ultrasound for biliary it is important to reference the symptom or the sign as the clinical indication and not the diagnosis. ie Patient with “RUQ pain” or “biliary colic” is acceptable Patient with “R/O choledocholithiasis” is not acceptable. Patient with “biliary colic R/O choledocholithiasis is optimal The examination is called a “limited RUQ ultrasound”
PATIENT PREPARATION The patient for US should be fasting for 4 hours and the study should take about thirty minutes
CLINICAL RED FLAGS:
A triad of jaundice, fever and RUQ pain (Charcot’s triad) is indicative of cholangitis, which has a high mortality if not treated promptly with appropriate antimicrobials (to cover enterococcus and enteric organisms, typically 3rd generation cephalosporin and metronidazole). Persistent epigastric pain radiating to the back associated with shock may indicate acute pancreatitis from impaction of a gallstone at the sphincter of Oddi.
Web Resources American College of Radiology Acute Abdominal Pain and Fever Acute Right Upper Quadrant Pain |