The incidence of gallstones in patients in the United States approaches 20% of men and 35% of women by the age of 75 years; ²⁴ thus, gallstones exhibit a greater prevalence in women and in older age groups. Obesity and certain diseases also are associated with the development of gallstones (Table 30-2).

Ultrasonography generally is the preferred imaging modality for evaluating patients for possible gallstones or biliary duct obstruction. Gallstones produce hyperechoic foci with acoustic shadowing, and mobility of the stone usually is apparent (Fig. 30-1). ^5,15 The patient should fast for 4 or more hours because these stones can be missed in a contracted gallbladder. ²⁵

These stones may be imaged incidentally on plain film radiographs even in asymptomatic patients, but only 10% to 15% of them contain enough calcium to be visible (FIG. 30-2FIG. 30-3 and FIG. 30-4). ^11,31 Oral cholecystography (OCG) requires the patient to take an oral contrast agent, which is absorbed from the bowel, excreted by the liver, and concentrated in the gallbladder (except when the gallbladder cystic duct is blocked or sometimes when the gallbladder is inflamed). The gallbladder also is not seen in cases of a lack of absorption or significant liver damage.

OCG does demonstrate most gallstones, but since the development of ultrasound to accomplish this task, it is thought by some to be most useful for providing information about the functional status of the gallbladder (see Fig. 30-3). ⁷ However, the clinical usefulness of this is still controversial.

Uncommonly, the noncontrasted gallbladder forms a radiodense “milk of calcium” bile that mimics the gallbladder’s appearance during OCG (Fig. 30-5). This phenomenon is thought to develop from chronic obstruction of the cystic duct by one or more gallstones in patients with chronic cholecystitis. The duct obstruction leads to decreased gland function, bile stasis, and radiographic visible accumulations of a radiodense calcium carbonate in viscous intraluminal bile. Review of the patient’s history to exclude any recent intake of contrast material (oral or intravenous) must be accomplished before the milk of calcium bile diagnosis can be made. On radiographs, the fluid is found in the gravity-dependent portion of the gallbladder. The ultrasound appearance is not consistent because the composition of the milk of calcium bile varies from a semisolid to fluid suspension.

“Porcelain gallbladder” describes extensive calcification of the wall of the gallbladder; also known as calcifying cholecystitis or cholecystopathic chronica calcarea (Figs. 30-6 and 30-7). Specifically the term refers to the blue-greenish discoloration and brittle condition of the gallbladder observed at surgery. A porcelain gallbladder typically is found incidentally on plain film studies. Patients generally are asymptomatic and more commonly are women (5:1 ratio). Concurrent gallstones are usual. A porcelain gallbladder is associated with higher incidence of adenocarcinoma of the gallbladder, typically warranting prophylactic excision.

Cholelithiasis usually is discovered incidentally during other studies. In the first 5 years after diagnosis, only approximately 10% of patients experience symptoms resulting from gallstones. ³¹ Right upper quadrant pain is the most commonly reported symptom. ³¹ The pain usually is steady, lasting for several hours. Radiation to the lower abdomen, back, or tip of the right scapula is not uncommon; vomiting may occur. ⁵

Complications seen with gallstone disease include cholecystitis, choledocholithiasis, pancreatitis (migration of a stone to the distal common duct where the pancreatic duct enters), cholangitis, stone perforation of the duodenum or colon, and gallstone ileus (Table 30-3). ^2,3,5,19,31 Symptomatic gallbladder disease may require surgical intervention if nonsurgical techniques such as lithotripsy (using strong ultrasound waves to break up the stone) are ineffective, unsuitable, or unavailable. ³¹

Colon polyps are found in up to 12% of the population. ³³ The adenomatous polyp is considered the precursor to colorectal cancer. ¹⁶ Therefore detection of colonic polyps is extremely important. The incidence of malignancy increases with increased size of the polyp (Table 30-4). Most polyp development is incidental, but polyps also appear as part of familial polyposis syndromes (not common). Table 30-5 reviews the characteristics of several polyposis conditions.

Barium examination and endoscopy are the most important methods for detecting polyps. ³² Polyps appear as discrete masses, sessile or pedunculated, which protrude into the lumen of the gut (FIG. 30-8FIG. 30-9 and FIG. 30-10). Recent investigations report up to 98% accuracy in identification of polyps by double-contrast barium enema. Older studies report less accuracy, but the accuracy depends on the meticulousness and quality of the exam. Lesions smaller than 1 cm in diameter are more difficult to detect.

In general the inner margin of a polyp appears sharper than the outer margin because it is an intraluminal mass surrounded by barium. On occasion a diverticulum coated with barium and filled with air can mimic a polyp on one or more x-rays, but with meticulous evaluation it should not be misdiagnosed.

Most patients with multiple small polyps or even small carcinomas have no overt symptoms. Chronic occult blood loss from polyps may lead to iron deficiency. Occasionally, symptoms from large polyps are related to complications such as intussusception or colonic obstruction. ³² Polyps measuring 1 cm or larger definitely should be removed and histologically examined, although some experts believe even smaller ones should be removed also.

Colorectal cancer is second only to lung cancer in men and breast and lung cancer in women as a cause of death. ³⁸ The incidence of colorectal cancer increases after 35 to 45 years of age; however, high-risk persons (Table 30-6) develop colorectal cancer at a much younger age. ^26,34 Most colorectal cancers are thought to arise from malignant transformation of an adenomatous polyp. ³⁴