Jaundice is the yellow discoloration of the skin and eyes caused by elevated bilirubin in the bloodstream. Bilirubin is a yellow pigment formed when old red blood cells break down. Obstructive jaundice, also known as post-hepatic jaundice, occurs when a mechanical blockage prevents the normal flow of bile, which contains bilirubin, from the liver or gallbladder into the small intestine. This physical obstruction causes bile to back up, forcing its components back into circulation.
Defining Obstructive Jaundice
The liver normally processes bilirubin, converting the water-insoluble form (unconjugated) into a water-soluble form (conjugated bilirubin). This conjugated bilirubin is then excreted into bile, traveling through the bile ducts for release into the digestive tract. Bile’s primary role is to aid in the digestion and absorption of fats in the small intestine.
In obstructive jaundice, a physical barrier stops the flow of bile, often at the common bile duct. This blockage causes bile to accumulate and exert pressure within the ducts, forcing the conjugated bilirubin to leak back into the bloodstream. Since conjugated bilirubin is water-soluble, it is filtered by the kidneys and excreted in the urine. This elevated level of conjugated bilirubin in the blood is the defining biochemical feature of the condition.
Common Causes of Bile Duct Blockage
The most frequent cause of bile duct obstruction is the presence of gallstones, a condition known as choledocholithiasis. These hardened deposits of cholesterol or bile pigments form in the gallbladder but can migrate out and become lodged in the common bile duct, creating a physical barrier.
Malignancies represent another significant and often more serious cause of obstruction. Cancers originating in the head of the pancreas can compress the bile duct as it passes through the organ, halting the flow of bile. Tumors arising directly from the bile ducts themselves, called cholangiocarcinoma, also cause blockages from within the ductal walls.
Inflammatory conditions can also lead to narrowing, or strictures, of the bile ducts. Pancreatitis, inflammation of the pancreas, causes swelling that can compress the adjacent common bile duct from the outside. Chronic inflammation can result in scarring and permanent strictures within the bile duct, causing a persistent obstruction.
Recognizable Signs and Symptoms
The most noticeable sign of obstructive jaundice is icterus, the yellowing of the skin and the whites of the eyes, resulting from bilirubin accumulation in the tissues. Patients frequently experience generalized itching, medically known as pruritus, which is caused by bile salts depositing under the skin.
Two other hallmark symptoms are changes in waste product color. Urine becomes dark because excess water-soluble conjugated bilirubin is excreted through the kidneys. Conversely, stools become pale, or clay-colored, because the bilirubin that normally colors feces is prevented from reaching the intestine.
If the obstruction is caused by gallstones or acute inflammation, patients may also experience abdominal pain, often localized to the upper right quadrant. Systemic symptoms like fatigue, loss of appetite, and weight loss are also common, particularly when the obstruction is caused by a malignancy.
Diagnostic Procedures
The initial step in confirming the diagnosis involves blood tests, such as a liver function panel. These tests show elevated enzymes, including alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (GGT), which are released when bile ducts are blocked. Crucially, the tests confirm a high level of direct or conjugated bilirubin, differentiating it from other causes of jaundice.
Imaging is then used to locate the obstruction and determine its nature. An abdominal ultrasound is usually the first line of investigation because it is non-invasive and can quickly identify dilated bile ducts or the presence of gallstones.
If the ultrasound is inconclusive or suggests a mass, specialized imaging is utilized.
Magnetic Resonance Cholangiopancreatography (MRCP)
MRCP uses magnetic resonance imaging to create non-invasive pictures of the bile ducts and pancreatic duct.
Endoscopic Ultrasound (EUS)
EUS involves passing an endoscope down the throat to use a small ultrasound probe near the affected area. This provides images and allows for tissue sampling if a tumor is suspected.
Targeted Treatment Options
The goal of treatment is to relieve the obstruction and address the underlying cause. Endoscopic Retrograde Cholangiopancreatography (ERCP) is a common and highly effective procedure for treating many obstructions. During an ERCP, an endoscope is guided to the opening of the bile duct, allowing a surgeon to remove stones or insert a stent.
A stent is a tube placed across the blocked segment of the duct to restore bile flow into the intestine. This method is the preferred palliative approach for obstructions caused by unresectable tumors, improving quality of life by relieving jaundice and itching. In cases where the blockage is caused by a benign stricture or a difficult stone, ERCP is often curative.
Surgical intervention is necessary for complex obstructions or for treating malignant causes. For cancers of the pancreatic head, the Whipple procedure may be performed to remove the tumor and reconstruct the digestive tract. If a tumor is too advanced for removal, a surgical bypass procedure may be performed to reroute the bile flow around the blockage.