APPROACH TO THE DIAGNOSIS OF JAUNDICE



A careful history and physical examination are of paramount importance in obtaining clues to the nature and cause of jaundice. A history of dark­ened urine invariably implies a conjugated hy­perbilirubinemia, while pale stools and pruritus suggest a cholestatic process. An inquiry into drugs, alcohol, exposure to jaundiced persons (drug or viral hepatitis), recurrent abdominal pain and nausea (gallstones), epigastric pain radiating into the back accompanied by weight loss and a distended gallbladder (carcinoma of the head of the pancreas), and pre-existing liver disease will often go far in delineating the probable cause for the jaundice. Routine laboratory tests are helpful in that serum transaminases are usually less than 10- to 15-fold elevated in patients with bile duct obstruction, while alkaline phosphatase levels are usually greater than two to three times normal. Conversely, a greater than 10- to 15-fold elevation of serum transaminases indicates hepatocellular disease. Serological tests for hepatitis may be helpful (see Chapter 43), whereas autoantibodies, if strongly positive, may be of diagnostic value, e.g., the antimitochondrial antibody in primary biliary cirrhosis.

Clinical evaluation and routine laboratory tests serve to identify the cause of jaundice in up to 85 per cent of cases. More sophisticated diagnostic procedures are often needed, however, to deter­mine the cause, especially whether the cholestatic jaundice in a given patient is intrahepatic or due to extrahepatic obstruction.

A diagnostic approach to this question is illus­trated in Figure 36-7. If extrahepatic obstruction is suspected, it is necessary to determine first by noninvasive means whether or not the major bile ducts are dilated. Dilatation of the ducts occurs when a mechanical obstruction is present, but is absent in cases of intrahepatic cholestasis. Either ultrasound or CT scanning may be used to deter­mine the caliber of bile ducts, the former generally preferred because of lesser cost and absence of radiation. Additional definitive clues, such as the presence of stones in the common duct or gall­bladder, may be obtained as well. However, both imaging techniques may give rise to false-positive and false-negative results in a small number of patients and cannot be regarded as truly defini­tive. Thus, in a patient with cholestatic jaundice, the absence of dilated ducts on ultrasound might not dissuade the clinician from proceeding to cho­langiography if the suspicion of extrahepatic ob­struction based on clinical evaluation is high. If dilated ducts are found on noninvasive imaging, direct cholangiography provides the most reliable approach to nonoperative diagnosis of cholestatic jaundice. This may be accomplished by either per­cutaneous puncture of the intrahepatic biliary tree with a thin needle (percutaneous transhepatic cholangiography) or by means of endoscopic retrograde cholangiography. The percutaneous route is simpler technically, has a success rate of close to 100 per cent in the presence of dilated ducts, is less expensive, and is thus the procedure of choice when dilated ducts are found on non­invasive imaging. The endoscopic route, although more demanding both technically and in terms of time and cost, is of value in demonstrating duct pathology when the bile ducts are not dilated (in which case the percutaneous route may often fail) or when associated pancreatic disease is present. It may also permit direct biopsy of lesions at the ampulla of Vater and sphincterotomy and stone extraction in appropriate instances.

Liver biopsy may be indicated when an intra­hepatic cause for cholestasis is strongly suspected on clinical grounds or when extrahepatic obstruc­tion is ruled out by definitive cholangiography. Liver histology itself is often a poor guide to whether cholestasis is intra- or extrahepatic. The decision to perform a biopsy thus will rest on the certainty with which extrahepatic obstruction has been excluded in a patient with cholestasis and on the clinical course of the disease. Thus, for ex­ample, in a patient with cholestatic jaundice in whom recent ingestion of chlorpromazine is doc­umented and in whom the jaundice is beginning to resolve following cessation of the drug, the best course may be to observe without further inves­tigation.