B | Nurse Key

Barium enema

Also called: (BE); Double-Contrast Barium Enema, (DCBE)

Purpose of the test

The barium enema is used to investigate and identify pathologic conditions that change the structure and function of the colon. It may be used as a screening test for early detection of colon cancer.

Basics the nurse needs to know

The barium enema is a radiographic test that is used to investigate the cause of a change in elimination patterns, melena (blood in the stool), obstruction of the colon, or the presence of an abdominal mass that has a suspected location in the colon. Barium is a contrast medium that is radiopaque, has a different density than body tissue, and can be instilled into hollow organs such as the colon. In the barium enema procedure, the entire colon and the distal portion of the ileum can be visualized on x-ray film (Figure 18). The technique may be done as a single contrast study that takes spot x-ray images of the colon with the barium filling the lumen. Alternatively, a double contrast study may be done. In this method, barium is instilled and then drained out of the colon, leaving a residual coating of contrast on the luminal mucosal surface. Then the colon is slowly filled with air that serves as a second contrast medium and also dilates the lumen of the colon. Spot x-ray images of the colon are taken after the contrasts are instilled completely.

Figure 18. Normal and abnormal barium enema images. A, Normal single contrast barium enema image of the colon. B, Abnormal single contrast barium enema image of cancer of the colon (arrowheads).

(A, From Frank ED, Long BW, Smith BJ: Merrill’s atlas of radiographic positioning and procedures, ed 12, St Louis, 2012, Mosby; B, From Major NM: A practical approach to radiology, Philadelphia, 2006, Saunders.)

REFERENCE VALUES

No lesions, polyps, tumors, or other abnormalities of the colon are noted. The mucosal lining is intact and the contour of the lumen is normal.

How the test is done

After the colon is emptied of feces, the contrast medium enema is administered by the radiology technologist. Barium and possibly additional air contrast are instilled as contrast media. If perforation is suspected or the patient is at risk for intraperitoneal leakage of the contrast, barium is not used and a water-soluble contrast medium is used in substitution. Fluoroscopic images are taken at intervals to monitor the instillation of the contrast. The patient must retain the contrast medium in the colon during the test. The patient’s positional changes, (supine, prone, lateral) are used to enhance gravity flow of the contrast medium throughout the entire colon. X-rays are taken to image the colon and in particular, the abnormal area(s). The procedure takes 45 minutes to 1 hour to complete.

Interfering factors

• Upper gastrointestinal series within 3 days before the test

• Inability to retain barium

• Incomplete pretest cleansing of the colon

• Recent myocardial infarction or cerebral vascular accident

NURSING CARE

Barium swallow

See Esophagography on p. 304.

Base excess/deficit

See Arterial Blood Gases on p. 139.

β-amyloid(1-42)

See Lumbar Puncture and Cerebral Spinal Fluid Analysis on p. 423.

Bilirubin, serum, urine

Includes: Total Bilirubin, Direct Bilirubin (Conjugated Bilirubin), Indirect Bilirubin (Unconjugated Bilirubin), Neonatal Bilirubin (Total Bilirubin, Neonatal)

Specimen or type of test:

Serum

Purpose of the test

Total serum bilirubin is the sum total of indirect bilirubin and direct bilirubin. The purposes of the total bilirubin test are to evaluate liver function, diagnose jaundice, and monitor the progression of jaundice.

The purpose of direct and indirect bilirubin tests is to identify the underlying cause of the elevated bilirubin level. In the newborn baby with jaundice, the neonatal bilirubin test is used to determine whether the infant needs treatment to prevent kernicterus (brain damage from high levels of bilirubin).

The purpose of the urinary bilirubin test is to identify the presence or absence of bilirubinuria in the diagnostic workup for liver and biliary diseases.

Basics the nurse needs to know

Most bilirubin is produced by the liver and spleen as part of the process of hemolysis (breakdown) of senescent (old) or damaged red blood cells. Once created, the bilirubin is transported in the bloodstream as indirect (unconjugated) bilirubin. The liver then converts indirect bilirubin to direct (conjugated) bilirubin. The direct bilirubin mixes with fluid and enters the bile canaliculi and hepatic ducts of the liver in the process that makes bile.

Bile, with its component direct bilirubin, flows from the hepatic ducts of the liver to the biliary ductal system. It is stored in the gallbladder and, on demand, flows through the cystic duct, the common duct, and enters the duodenum to help in the process of digestion of fats.

Jaundice

This is a clinical term that describes the yellow discoloration of the skin and sclera caused by excess bilirubin in the blood and body tissues. The jaundice becomes visible when the total serum bilirubin is elevated to greater than 2 mg/dL. An elevated level of bilirubin in the blood is called hyperbilirubinemia.

Classifications of jaundice

One way to classify jaundice is based on the physiologic location of bilirubin manufacture, transport, and excretion. As seen in Table 4, pathophysiologic changes will be detected by elevated values of the indirect or direct bilirubin tests. These tests help provide information about the cause of the problem. The prehepatic category refers to bilirubin manufacture and transport before the blood circulation reaches the liver. The hepatic category refers to problems within the liver because of injury to the liver cells or blockage within the intrahepatic bile ducts. The posthepatic category refers to blockage of bile within the liver or in the gallbladder or gallbladder ducts.

Table 4 Classifications of Jaundice

Category of Jaundice	Type of Bilirubin Elevation	Origin of the Problem
Prehepatic	Indirect (unconjugated)	Excessive hemolysis of red blood cells
Prehepatic	Hemolytic jaundice
Hepatic	Indirect (unconjugated)	Defect in transport or conjugation in hepatocytes
	Physiologic jaundice
	Direct (conjugated)	Injury to, or disease of, hepatocytes
		Blockage of intrahepatic bile ducts
		Intrahepatic cholestasis
Posthepatic	Direct (conjugated)	Blockage in the biliary ductal system
Posthepatic	Extrahepatic cholestasis

Neonatal jaundice

In the first few days of life, newborns experience varying levels of elevated bilirubin. The condition is called physiologic jaundice. It is not clear why this condition occurs, but it is temporary. The indirect bilirubin rises modestly for 3 to 4 days and then declines to a normal value.

Other causes of neonatal jaundice are considered abnormal or pathologic, including ABO and Rh incompatibility. The rapid destruction of red blood cells in hemolytic disease of the newborn causes a great increase in indirect bilirubin. The onset is usually in the first day of life. If the total bilirubin level is greater than 20 mg/dL (SI: 340 μmol/L), potential exists for bilirubin encephalopathy or kernicterus. In kernicterus, bilirubin is deposited in the brain and if untreated, permanent damage can occur.

If the infant is born with biliary atresia, the biliary drainage system is incompletely developed and there is no open passageway for bile to flow into the duodenum. Because of the blockage, a rapid, severe rise in total bilirubin and direct bilirubin will occur. Urinary bilirubin will be positive in biliary atresia and hepatic disease, but not in hemolytic jaundice.

There is no specific test for indirect bilirubin. The measurement of indirect bilirubin is a mathematical calculation made by subtracting the value of direct bilirubin from the value of total bilirubin.

Interfering factors

• Sunlight

• Hemolysis

• Failure to maintain a nothing-by-mouth status (adults only)

NURSING CARE

Nursing actions are similar to those used in other venipuncture or capillary puncture procedures (see Chapter 2), with the following additional measures.

Pretest

• Patient teaching.

Instruct the patient to fast from food for 8 to 12 hours (overnight) because serum lipids will alter the results.

Posttest

• Ensure that the tube of blood or the microcapillary tube or the urine sample is covered in aluminum foil and sent to the laboratory without delay. Because bilirubin is photosensitive, the specimens must be protected from exposure to light or a prolonged time in a lighted environment.

• The nurse remains vigilant for signs of neonatal jaundice, but observational assessment may not be reliable and is not the best method to detect elevated bilirubin at an early stage. In evidence-based nursing practice, the best approach is to systematically monitor the laboratory results for elevated total serum bilirubin values and identify those neonates who are at risk for hyperbilirubinemia (Watson, 2009).

Nursing response to critical values

If the neonatal serum bilirubin rises to a critical value in the newborn or premature infant, notify the physician immediately. If the elevation is considered to be pathologic, rather than physiologic, the baby must be evaluated medically to determine the cause of hyperbilirubinemia. At the level of the critical value, the physician will consider the treatment of phototherapy. If the level goes higher, phototherapy will be performed, and exchange transfusion may also be necessary.

Malignant primary bone tumors are characterized by borders that extend outward into the surrounding fat or muscle tissue or inward into the marrow and medullary cavity, or both (Figure 19). The most common primary bone malignancy is osteogenic sarcoma, which is often located in the region of the knee. Malignant bone tumors may also be metastatic tumors, with the primary site located elsewhere in the body. Most bone metastases are in multiple sites, usually located in the vertebrae, ribs, sternum, or pelvis.

Figure 19. Bone metastasis. A, The image of the femur in a patient with known lung cancer shows a destructive lesion expanding from the marrow space and thinning the cortex of the bone (arrows). It is important to locate lesions in weight-bearing bones so that therapy can be undertaken to prevent pathologic fracture. B, A view of the femur from the same patient, who returned 2 weeks later with a pathologic fracture.

(From Mettler FA: Essentials of radiology, ed 2, Philadelphia, 2005, Saunders.)

When a bone tumor is suspected, a bone scan or computed tomographic (CT) scan is performed first. These preliminary tests are used to verify the presence of the tumor and identify the site for bone biopsy. They also are used to identify additional metastatic sites and to help assess the extent of growth or invasion of the tumor. Unlike biopsy, the preliminary imaging cannot distinguish benign from malignant disease.

REFERENCE VALUES

Bone tissue is normal, with no tumor cells present.

How the test is done

Using local anesthesia, a small incision is made in the skin, and a bone biopsy needle is used to drill or push into the bone. Once it is in place, the biopsy needle is rotated 180 degrees to obtain a core sample of the tissue. The specimen is placed on a slide with fixative or in a specimen jar with 95% alcohol or both. Just before collection of the bone specimen for biopsy, a bone marrow aspiration for biopsy may be done in the same location.

Interfering factors

• Failure to obtain an adequate sample of tissue

• Failure to send the specimen to the laboratory immediately

NURSING CARE

During the test

• Provide support to the patient as the local anesthetic is injected into the skin and subcutaneous tissue and the biopsy needle is inserted. Despite the local anesthetic, the patient feels momentary pain as the needle penetrates the periosteum and enters the bone.

• The nurse labels all specimen containers and slides with the patient’s name and the tissue source. The requisition form for a tissue cytologic study is completed, including the patient’s name, age, history of carcinoma or infection, and the site of biopsy. The slides or specimen, or both, are sent to the laboratory without delay. The final preparation of the slides must be completed within 6 hours to prevent deterioration of the tissue.

Posttest

• The nurse assesses vital signs and monitors them at regular intervals until they are stable.

• Assessment findings should include observation that the pressure dressing remains clean, dry, and intact.

• Patient teaching.

The nurse instructs the patient to rest quietly with an ice pack over the dressing for about 2 hours. In preparation for discharge from the ambulatory setting, instruct the patient to resume routine activity but to avoid strenuous physical activity for a few days. The pressure dressing may be changed to a small adhesive bandage on the day after the procedure, and a shower is permitted. Mild discomfort is common, and the patient can take an analgesic medication as needed.

♦ Nursing response to complications

Infection.Infection of the bone is a rare, but possible complication. If infection occurs, the patient develops a fever and headache. He or she feels bone pain and pain on movement. The biopsy site becomes red, with purulent drainage or an abscess. The nurse instructs the patient to notify the physician if these symptoms occur.

The bone marrow aspiration or biopsy, followed by microscopic examination of the tissue, is used to evaluate hematopoiesis. It diagnoses malignancy of primary and metastatic origin and determines the cause of infection. The examination of the marrow also is used to evaluate the progression of some hematologic diseases or the response of the marrow to chemotherapy treatment, such as in Hodgkin disease and acute myelogenous leukemia.

Basics the nurse needs to know

The bone marrow is responsible for hematopoiesis—the formation of blood cells. The aspirated cells of the bone marrow are used to investigate hematologic disorders. A small sample of the cells is often representative of the whole marrow. Microscopic examination of the cells provides information about the cause, type, and extent of the abnormality. A peripheral blood smear is performed on the same day to compare and incorporate pertinent findings.

The marrow cells are examined for characteristics of the tissue including cellularity, the proportion of aspirate that is hematopoietic cells rather than fat cells; distribution, an estimate or count of the number of each type of cell found in the marrow specimen; maturation, the balance of cells in stages of development; and abnormal cells, the presence of irregular or abnormal cells in the marrow. In addition, the examination provides data about the underlying cause of the abnormality in the cells of the blood.

Leukocytes from the marrow have a number of different proteins attached to the cell surfaces. Many blood disorders have distinctive distributions and patterns of the proteins on these cell surfaces. In the presence of fluorescent antibodies, the different cellular proteins will react and bond with specific antibodies and the analysis of the cell patterns provides for many diagnoses. The proteins serve as markers to help diagnose different diseases, such as leukemia and lymphoma, and can distinguish between different types of each of these cancers (Jenkins, Karunanithi, & Hewamana, 2008).

Genetic testing of bone marrow cells

Cytogenic studies are performed to identify acquired disorders of chromosomes in malignant cells of the marrow. The alterations provide information about the type of malignancy and prognosis in response to conventional cancer therapy.

Molecular analysis examines the DNA in nuclei of the white blood cells in the marrow specimen, identifying the altered or defective DNA. When molecular defects are identified, they can be used to monitor the response to therapy or identify a relapse at an early stage when additional treatment can still be effective. The cancer patient who is undergoing treatment or who is in remission will need to undergo repeated, planned bone marrow aspirations and biopsies over time. This process of surveillance of bone marrow cells is called minimal residual disease monitoring.

REFERENCE VALUES

Normal bone marrow.

How the test is done

A local anesthetic is injected in the skin, into subcutaneous tissues, and at the bone site. In bone marrow aspiration, a bone marrow needle is inserted into the medullary cavity of a bone. Fluid and marrow cells are aspirated into several syringes. When a bone marrow biopsy is required, a wider, bone trephine needle with an inner core is inserted. After the inner core is removed, the hollow, outer component of the needle is advanced into the marrow and a core of marrow tissue is removed. Slides are prepared and tissue specimens collected. When indicated, culture specimens are obtained.

The aspiration and biopsy sites include the iliac crest and proximal tibia (Figure 20). In adults, the posterior iliac crest is the best site. In infants and young children, the proximal tibia is used. The sternal site is only used for obese patients.