Handwritten Lecture on symptoms and treatment for choledocholithiasis for medical students studying for USMLE Step 1, USMLE Step 2, and USMLE Step 3 review.
During your USMLE review, it is helpful to watch this video and then attempt questions in the Kaplan QBank or UWorld QBank.
INTRODUCTION 0:00
ANATOMY OF GALLBLADDER AND BILIARY SYSTEM 00:29
PATHOPHYSIOLOGY OF GALLSTONES 02:02
SYMPTOM OF CHOLECHOLITHIAIS 03:30
TRANSABOMINAL ULTRASOUND 07:30
MRCP 09:10
ENDOSCOPIC ULTRASOUND 12:25
ERCP 15:36
TREATMENT 21:14
Choledocholithiasis refers to gallstones in the common bile duct.
ANATOMY & PHYSIOLOGY OF GALLSTONE IN COMMON BILE DUCT
The gallbladder is made up of a cystic duct which combines with hepatic duct to form a common bile duct. This merges with pancreatic duct and through the sphincter of Oddi. The gallbladder is positioned behind the liver and the common bile duct is goes behind the duodenum and through the pancreas.
PATHOPHYSIOLOGY
Within the gallbladder, a gallstone may be formed. In the setting of choledocholithiasis, the gallstone is formed in the gallbladder approximately 90% of the time time. gallstone lodges into the cystic duct, it is then cholecystitis. However, if trapped in the common bile duct, it is known as choledocholithiasis. If the gallstone is trapped behind the pancreas it can cause pancreatitis.
SYMPTOMS OF GALLSTONE IN COMMON BILE DUCT
The typical pain is typically in the right upper quadrant extending to epigastric. They may have referred pain to the right shoulder and scapula. The pain of choledocholithiasis lasts longer that gallstones or cholecystitis, lasting up to 4-6. If the choledocholithiasis is uncomplicated the patient will be afebrile or they may rarely be asymptomatic. On examination, patients will be jaundiced and have abdominal tenderness. Labs can help differentiate choledocholithiasis between gallstones and cholecystitis. This is important to consider when tackling questions for USMLE Step1 and performing Kaplan QBank and UWorld QBank. The typical lab findings are elevated liver enzymes and bilirubin as well as ALP and GGT. These labs are important in distinguishing from gallstones and cholecystitis when taking the USMLE Step 1, USMLE Step 2, or USMLE Step 3. During your reviews with Kaplan QBank and UWorld QBank make sure to pay attention to these lab values.
There are several complications to be aware of in choledocholithiasis. Pancreatitis which will have elevated amylase/lipase. Cholangitis presenting with Charcot's Triad and Reynald pentad which is added altered mental status and sepsis. Secondary biliary cirrhosis develop in longstanding choledocholithiasis. These complications will not occur with gallstones and cholecystitis.
INVESTIGATIONS OF GALLSTONE IN COMMON BILE DUCT
The first imaging modality for choledocholithiasis is a transabdominal ultrasound. It may sometimes visualize the actual gallstones, but this is difficult if the gallstone is in the distal common bile duct. Typically in choledocholithiasis, you will see a dilated common bide duct, typically greater than 6mm. But this is suggestive, not diagnostic. Not helpful in post-cholecystectomy patients as their common bile duct may be greater than 10mm.
MRCP is also known as magnetic resonance cholangiopancreatography which provides better visualization of the intrahepatic and extrahepatic biliary systems. MRCP can be done with or without contrast which is helpful in patients sensitive to contrast. However, MRCP can show bile ducts and pancreatic ducts. The benefits of MRCP are that it is non-invasive, however, it takes a long time, and there may be contraindications. While you are reviewing USMLE make sure you understand when this test is indicated.
Endoscopic ultrasound is another diagnostic test that can help identify gallstones in the common bile duct. It can also diagnose gastric pathologies. With the endoscopic ultrasound, you can directly visualize the gallstones in the common bile ducts. It is much closer to the common bile duct and it is much easier to visualize the stone and help rule out cholecystitis. This is helpful in patients with the previous cholecystectomy because the common bile duct is dilated and therefore can't diagnose gas stone in the common bile duct. ERCP can be done immediately after. However, the downside of endoscopic ultrasound is that it is invasive.
ERCP is short for endoscopic retrograde cholangiopancreatography. It is similar to endoscopic ultrasound, however, a stylus extends and injects contrast to visualize the biliary system and pancreatic ducts. If a gallstone is detected a sphincterotomy with balloon dilation can be performed. If necessary the gallstone can be manually retrieved. For the purposes of USMLE remember, this is only done if the diagnosis of choledocholithiasis is very clear as this is not only diagnostic, but also therapeutic.