Purpose of the test

Ultrasound examines organs, blood vessels, and structures of the body to identify malposition, malformation, malfunction, or the presence of a foreign body. It also may be used as a visual guide for accurate placement of a needle in a biopsy or aspiration procedure. In pregnancy ultrasound, the test is used to determine the age of the fetus and gestation of the pregnancy, as well as to assess for possible congenital or genetic malformation.

Basics the nurse needs to know

Ultrasound is a scanning procedure that transmits sound waves in a directed path through the skin and into body tissues. The sound waves quickly bounce back or “echo” when they encounter a solid structure or tissue of different density (Figure 94). The sound waves are converted to a visual image that can be analyzed for abnormality.

Figure 94. Ultrasound of the liver. The scan shows multiple cancer metastases (M) in the right lobe of the liver. In the ultrasound image, the gallbladder (GB) is seen along the upper right border of the liver. In this patient, the primary site of the cancer was in the colon.

(From Frank ED, Long BW, Smith BJ: Merrill’s atlas of radiographic positioning and procedures, ed 11, St Louis, 2007, Mosby.)

The ultrasound pulsations transmit through fluid and body tissue, but do not transmit through air, bone, or barium. When the sound wave signals pass through tissues of varying densities, the most common images are in varying shades of white, gray, and black that correspond to the tissue size, shape, structure, and density.

Doppler ultrasound is a different method of ultrasound. It detects the presence, direction, speed, and character of arterial or venous blood flow within the vascular lumen. The Doppler pulses echo off the moving erythrocytes in the blood in patterns that correlate with the flow of the blood. The echoes are converted to an audio signal, a linear graphic reading, or color images that demonstrate the flow of blood in a designated area of an artery or vein. The audio signal changes according to the character of the blood flow. The blood flow may be characterized as normal; disturbed, as at the bifurcation of a blood vessel; or turbulent, as encountered beyond the point of a partial obstruction. Severely obstructed circulation produces a weak signal or silence. This type of ultrasound is very helpful in assessing the circulation in a vascular graft after bypass or transplant surgery has been performed (see also Ultrasound, Doppler, Vascular, pp. 597-601).

Transducer

The transducer, in the form of a scan head or probe, is the instrument used to generate and transmit the ultrasound energy and then receive the echo sound waves that bounce back from the tissue within. The returning sound waves are converted to audio signals or visual images. When the transducer is used externally, the scan head is moved over the skin in defined patterns, according to the anatomic location of the target tissue and the viewing plane that is desired. Other transducers are specialized probes used within the body. These probes can be used in the esophagus, vagina, rectum, or lumen of a blood vessel. The internal application is useful because the sound waves are placed near the particular organ or tissue. The procedure reduces or eliminates the interference of other tissues and of the air of the lungs or bowel.

Many different ultrasound scans are used to examine organs, tissues, lymph nodes, and the vascular circulation. The more common scans are listed in Box 10.

BOX 10 Ultrasound Procedures

Popliteal artery scan

Inferior vena cava scan

Abdominal aorta scan

Carotid artery scan

Abdominal scan

Liver scan

Gallbladder, biliary tract scan

Pancreas scan

Renal scan

Spleen scan

Pelvic scans

Female pelvic scan

Obstetric scan

Endovaginal scan

Male pelvic scan

Thyroid scan

Scrotum scan

Breast scan

Transesophageal echocardiography

Echocardiography

Abdominal ultrasound

Ultrasound is a major diagnostic tool for the examination of the liver, hepatobiliary tract, spleen, and pancreas. In the liver, it can detect a cyst, abscess, hematoma, primary neoplasm, and metastatic tumor. It is the best diagnostic tool to detect gallstones (Figure 95). It also may show thickening of the gallbladder walls associated with acute cholecystitis or dilation of the biliary tract associated with obstruction. An enlarged or edematous pancreas is measurable by ultrasound. Pancreatic abscesses, pseudocysts, and pancreatic tumors are readily identified. Ultrasound identifies a congenital absence of the spleen or the existence of multiple spleens. It can also identify the presence and size of space-occupying lesions, such as cysts or tumors, and is accurate in the measurement of the size of the spleen.

Figure 95. Gallbladder ultrasound. A, A large gallstone (ST) within the gall bladder; B, A distended gallbladder because of a small gallstone (long arrow) lodged in the distal cystic duct (short arrowhead).

(From Frank ED, Long BW, Smith BJ: Merrill’s atlas of radiographic positioning and procedures, ed 11, St Louis, 2007, Mosby.)

Cardiac ultrasound

Two cardiac ultrasound procedures are covered separately in detail in this text: Transesophageal Echocardiography (pp. 587-590) and Echocardiogram (pp. 270-271).

Renal ultrasound

Renal ultrasound clearly defines the kidneys, including their size, shape, position, collecting systems, and surrounding tissues. Renal masses that are greater than 2 cm are readily detected, and renal cysts are a frequent finding. Ultrasound can identify the location and severity of obstruction. Renal ultrasound may be used as a guide for needle placement in renal biopsy, for drainage of a renal abscess, or for placement of a nephrostomy tube.

Pelvic ultrasound

In the diagnosis of gynecologic problems in the female, one use of ultrasound is to identify an ovarian malignancy at an early stage. In the case of abnormal uterine bleeding, ultrasound will identify submucous leiomyomas and evaluate the thickness of the uterine wall. Pelvic ultrasound often precedes any invasive gynecologic diagnostic test, such as dilation and curettage. The procedure may also be used to monitor ovulation in the diagnosis and treatment of infertility and in follow-up after treatment for pelvic inflammatory disease. For the female, the examination consists of imaging from both transabdominal and transvaginal approaches to obtain complete visualization.

Ultrasonography in the male is used to assess the texture, size, and condition of the prostate gland, prostatic urethra, seminal vesicles, vas deferens, and testes. It is also used to guide the placement of the needle during biopsy of the prostate gland. Ultrasound is part of the diagnostic workup to detect and stage prostate cancer.

Pregnancy ultrasound

In conditions related to pregnancy, ultrasound identifies an early ectopic pregnancy, a multiple pregnancy, possible fetal abnormality, and assessment of fetal growth (see also Genetic Sonogram, pp. 328-331). It is also used to guide aspiration procedures including amniocentesis, cordocentesis, periumbilical cord sampling, and the aspiration of multiple oocytes for in vitro fertilization.

Thyroid ultrasound

An ultrasound of the thyroid gland is usually done to investigate goiter (enlargement of the thyroid gland), a palpable nodule or cyst, and to identify tumors. The patient lies flat with a rolled towel under the posterior neck, which causes hyperextension of the neck

REFERENCE VALUES

No anatomic or functional abnormalities exist. The organs are normal in size, shape, contour, and position. The internal structures of the organs and nearby tissues are within normal limits.

How the test is done

High-frequency sound waves from the transducer are directed into an area of the body in a specific pattern. The echoes of the ultrasound are converted to visual images, linear tracings, or audible sounds.

Significance of test results

Interfering factors

Purpose of the test

In vascular studies, Doppler ultrasound detects stenosis or occlusion in an artery (Figure 96) or vein, assists with the diagnosis of peripheral vascular or cerebrovascular disease, evaluates the results of arterial reconstruction or vascular bypass surgery, and assesses for possible trauma to an artery.

Figure 96. Carotid artery ultrasound. The arrow identifies plaque within the lumen of the internal carotid artery. The lumen is partially occluded.

(From Rumack C, Wilson SR, Charboneau JW: Diagnostic ultrasound, ed 3, St Louis, 2005, Mosby.)

Basics the nurse needs to know

The Doppler ultrasound transducer transmits low-intensity sound waves that are directed at a specific blood vessel. The transmitted sound waves strike moving red blood cells and bounce back to the transducer-receiver. The received impulses are translated into an audible signal, a visual image, or a waveform recording. Additionally, the systolic pressure in the upper and lower extremities can be measured.

Using the audible signal, changes in the pitch and volume of the blood flow can be heard. When the blood flow is normal, the sound is loud and of higher pitch. Conversely, when blood flow is constricted or partially obstructed, the sound is softer or fainter and the pitch is low. Total obstruction in a blood vessel produces no sound at all.

Waveform recordings are used to evaluate the circulation in lower extremities. The waveform recordings are Doppler signals that are transformed into a linear image. The waveforms are recorded on a graph paper and appear on the monitor (Figure 97). In abnormal venous flow, as in partial or total venous occlusion, the augmentation signal of an upward spike is absent. Reflux flow, such as that caused by incompetent venous valves, is also evident on the waveform. The normal arterial waveform is characterized by three phases called the systolic, diastolic, and wall rebound phases. When the artery is stenosed, the waveform pattern diminishes in height. In severe obstruction, the diastolic phase and wall rebound phase are absent.

Figure 97. Normal versus abnormal Doppler arterial waveform patterns. A, Normal waveform with triphasic pattern of sharp upstroke and downstroke and good amplitude. 1, systolic component; 2, diastolic component; and 3, elastic wall rebound. B, Abnormal waveform pattern with monophasic pattern of low amplitude and flat waves. This pattern indicates severe arterial obstruction.

Color-flow Doppler imaging demonstrates the change in blood flow in various colors. Blood flow that moves toward the transducer is imaged as a shade of red. Blood flow that moves away from the transducer is imaged as a shade of blue. When blood flow within the artery or vein is normal, the color is intense, and the lumen of the blood vessel should be filled with color. With obstruction of the blood flow, such as with deep vein thrombosis, the color fades from red to orange or yellow or from blue to aqua or white. This method may be used to assess cranial neck vessels and is also used to assess the abdominal aorta and the peripheral vascular system. The technique can detect an embolus, stenosis, a thrombus, an aneurysm, and venous insufficiency.

How the test is done

Significance of test results

Interfering factors

NURSING CARE

Pretest

• After the physician has informed the patient about the test, obtain a written consent from the patient.

•   Patient teaching.

The nurse instructs the patient to avoid nicotine, alcohol, caffeine, and other stimulants and depressants that will cause vasoconstriction. To help control the patient’s anxiety, the nurse reassures the patient that the test is painless.

• In most cases, vascular testing will be done in a radiology setting or a vascular laboratory. The room lighting should be reduced to promote relaxation. The patient will put on a hospital gown. For arterial tests, the patient is in the supine position. For venous tests of the lower extremities, the patient is placed in the supine position with two pillows under the legs to elevate them above the heart. The leg and hip are externally rotated, and the knee is flexed (Figure 98).

Figure 98. Doppler ultrasound of venous circulation in the legs. The patient is supine with the head of the bed slightly elevated. The Doppler transducer is placed over locations on the various veins where the circulation can be detected ultrasonically.

(From Pfenninger JL, Fowler GC: Pfenninger and Fowler’s procedures for primary care, ed 3, St Louis, 2011, Mosby.)

During the test

• The procedure is to locate the pulse points on the upper or lower extremities and apply acoustic gel. At each pulse point, apply the transducer head to the skin and listen to the blowing sounds produced by the audio mode of the Doppler instrument.

Posttest

• Remove the acoustic gel from the skin. Record the findings in the patient’s record.

• At the bedside, the nurse may perform ongoing audio Doppler assessments of pulses, particularly on the patient who has lower limb ischemia and pulses that are too faint to be palpated. The assessments may also be done to check the distal blood flow after a vascular graft or bypass graft is in place.

Purpose of the test

The upper GI series detects disorders of structure or function of the esophagus, stomach, and duodenum. One week postoperatively, it is used to evaluate the results of gastric surgery. As an extension of the upper GI series, the small bowel series detects disorders of the jejunum and ileum.

Basics the nurse needs to know

The upper GI series involves a radiologic examination from the oral part of the pharynx to the duodenojejunal junction. When the small bowel requires examination, the small bowel series often follows the upper GI series directly, but it can be performed as a single procedure. The common sources of abnormality in the upper GI tract are stricture, inflammation, swelling, ulcers, tumors, motility disorders, or structural changes in the wall of the intestine.

The barium liquid is a radiopaque contrast medium that outlines the size, shape, and contour of the intestinal lumen. Air may be instilled to provide double contrast and better visualization of the lumen of the esophagus, stomach, and duodenum. Fluoroscopy and x-ray films are used at intermittent intervals to obtain the gastrointestinal images.

How the test is done

Upper gastrointestinal series

The patient drinks a barium solution to provide contrast views during swallowing and peristaltic action in the esophagus. As the barium coats the mucosal lining of the stomach, additional films are taken to outline the shape and contour of the organ. The patient’s positional changes (vertical, supine, prone, and lateral) help coat the mucosa throughout the stomach. With positional changes, the barium will flow into an ulcer and fill the crater (Figure 99).

Figure 99. Upper GI series. Barium fills the crater of a round peptic ulcer (arrow) located near the lesser curvature of the stomach.

(From Gore RM, Levine MS: Textbook of gastrointestinal radiology, ed 3, Philadelphia, 2008, Saunders.)

Small bowel series

When a small bowel series is included in this radiologic study, the transit time of the barium can be from 30 minutes to 6 hours before it reaches the colon. At the start of the small bowel series, additional barium is taken orally. The transit time can be shortened by having the patient drink 200 mL of iced water or eat a light meal after all the additional barium has left the stomach. Fluoroscopic views are taken three times in the first hour and every 30 minutes thereafter. Radiographic films are taken of any abnormality.

Enteroclysis method

When the small bowel series is performed separately, enteroclysis may be used to instill the barium. A radiopaque catheter is passed through the nose or mouth and advanced past the pylorus and into the duodenum. Barium, followed by methylcellulose solution, is instilled by the catheter route directly into the small bowel. Views of the total small bowel can be completed in 20 to 30 minutes.

Significance of test results

Abnormal values

Esophagus

Reflux esophagitis

Esophageal scarring or stricture

Barrett’s esophagus

Infectious esophagitis

Stomach-duodenum

Peptic ulcer (gastric, duodenal)

Cancer (stomach, duodenum)

Pyloric obstruction

Benign tumor

Gastric inflammatory disease

Perforation

Diverticula

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