PEARLS for an Ultrasound Physical and Its Routine Use as Part of the Clinical Examination

Michael Wagner, MD; Janice Boughton, MD

Disclosures

South Med J. 2018;111(7):389-394. 

In This Article

PEARLS Detailed Description

Parasternal

Beginner User. For many beginners, the parasternal long-axis (PLAX) view serves as the "home screen" view of the heart. Using a cardiac preset and the probe marker pointing toward the right shoulder, the probe is placed just to the left of the sternum around the third or fourth intercostal spaces. Once an adequate window is located, the probe is adjusted so that the US beam cuts through the midline of the left ventricle in its long axis, with a depth setting that is sufficient to see the descending aorta. A small pericardial effusion can be visualized as an anechoic (black) region separating the posterior wall of the left ventricle and the pericardium, tracking anteriorly to the descending aorta. Large pericardial effusions will surround the heart both posteriorly and anteriorly.

Advanced User. An assessment for numerous pathologies is possible using the PLAX view (Table), from detecting left ventricular dysfunction to clarifying the probable etiology of a murmur. From the PLAX view, one can turn the probe marker 90° toward the patient's left shoulder and obtain parasternal short axis views (from base to apex). One can verify findings in the PLAX view and look more closely at chamber shape and wall motion. In patients with good parasternal windows but difficult apical or subxiphoid views, fanning the beam from the PLAX view toward the patient's right allows the visualization of tricuspid valve and right atrial pathology.

Epigastric

Subxiphoid Cardiac Views. Beginner User; Using a cardiac preset and pointing the probe marker toward the patient's left, the probe is placed just below the xiphoid process, with the probe face pointing up toward the patient's neck. The liver is used as a window to shine the US beam into the chest to view the heart. Once an adequate window is located, the probe is adjusted so that the US beam cuts through all four chambers, with the mitral and tricuspid valve in the same plane of cut. This view is useful for the accurate detection of small pericardial effusions, particularly in patients who are semi-upright.

Advanced User; In the patient with difficult parasternal views, such as patients with chronic obstructive pulmonary disease, the four-chamber subxiphoid cardiac view can be modified to obtain short-axis and long-axis views of the heart by turning the probe marker to the ceiling and toward the patient's right shoulder, respectively.

Great Vessel Views. Beginner User; With the probe in the abdominal preset and the probe marker pointing toward the patient's head, the probe is placed just below the xiphoid process, with the probe face pointing posteriorly. The liver is used as a window to visualize the IVC just anterior to the vertebral bodies as it dumps back into the right atrium (RA). Once an adequate window is located, the probe is adjusted so that the US beam cuts through the middle of the IVC along its long axis. Size and respiratory variation are assessed within 2 to 3 cm distal to the RA junction to make determinations about intravascular volume and central venous pressure. It is good practice to fan the probe beam and visualize the aorta, as well as to ensure that it is not mistaken for IVC. If the user is unsure, he or she should feel the patient's radial pulse while scanning; pulsations in time with the pulse indicate that the vessel is the aorta.

Advanced User; Starting from the four-chamber subxiphoid cardiac view, the RA should be identified. Next, the probe face should be fanned from cranial to caudal, so that the RA becomes the IVC in short axis. One can usually see the hepatic veins draining into the IVC just caudal to the diaphragm. Assessing the size and flow pattern on color Doppler of the hepatic veins also can serve as useful adjuncts when the central venous pressure is not clear by the IVC alone. This transverse epigastric view also can visualize right pleural effusions posterior to the diaphragm and can serve as a window for pancreatic pathology and paraaortic lymph nodes in the abdomen.

Anterior Lung

Beginner User. With the probe in the lung or abdominal preset and the probe marker pointing toward the patient's head, the probe is placed between the ribs at the right and left second intercostal spaces. The ribs frame the image, with the pleural line (lung surface) visualized to be "sliding" just beneath them. Fan the probe so it is perpendicular to the anterior lung surface and the deeper underlying artifact pattern (horizontal A-lines or vertical B-lines) are seen. Seeing a B-line pattern can be thought of as the US equivalent to hearing crackles on auscultation, and its presence bilaterally can suggest fluid in the lung parenchyma. An A-line pattern is suggestive of lungs that are relatively "dry," although the sensitivity of this finding in excluding pulmonary edema will depend on the clinical scenario.

Advanced User. Visualizing lung sliding artifact at the least-dependent positions of the anterior lung fields can be used to exclude pneumothorax in supine patients in the right clinical scenario. Although B-lines in the anterior lung fields are a more specific finding for pulmonary edema, the most sensitive region to identify B-lines usually is at the lung bases. To save time, in patients who have normal lung bases assessed in the right and left upper quadrant (RUQ, LUQ) views, the assessment of the anterior lungs often can be omitted, particularly in patients without a respiratory complaint. In patients with a respiratory complaint or hypoxemia, or any patient with abnormal findings at the bases, a more comprehensive look at the lungs should be used, sliding the probe along several intercostal spaces anteriorly, laterally, and occasionally posteriorly, depending on the pathology sought.

Apical

Beginner User. In adults the region of the cardiac apex that touches the chest wall frequently is smaller than a coin and often depends on the patient's position. As such, the apical window often is the most challenging to obtain in cardiac US and proficiency may develop more slowly than with other views.

Advanced User. Using a cardiac preset and the probe marker pointing toward the patient's left, the probe is placed around the fourth or fifth intercostal space, usually in the midclavicular line in normal hearts or more laterally displaced in cardiomegaly. The probe face points toward the patient's right scapula, and to ensure probe contact with the skin, it may be necessary to have the patient lie on his or her left side. Once an adequate window is located, the probe is adjusted so that the US beam cuts through all four chambers, with the mitral and tricuspid valves seen in the same plane. From a POCUS standpoint, this is the best cardiac view for assessing right heart size and function. Detecting right heart pathology such as pulmonary hypertension is facilitated by comparing corresponding chamber sizes of the right with the left. By rotating the probe marker 90° and 120° counterclockwise, one can add the apical two- and three-chamber views, respectively. These are useful when assessing regional wall motion abnormalities and assessing for valvular disease, particularly when other cardiac windows are limited. In patients with chronic obstructive pulmonary disease, an apical or subxiphoid window may be the only way to visualize the heart. An apical four-chamber view should be obtained routinely by those hoping to advance their POCUS skill set and those who need to maintain it, because it is a skill that can fade rapidly.

RUQ

Beginner User. With the probe in the abdominal preset and the probe marker pointing toward the patient's head, the probe is placed around the seventh or eighth intercostal space in the anterior or mid-axillary line, with the probe face pointing medially and posteriorly toward the patient's spine. The liver is used as a large window to visualize several structures in the abdomen and into the lower thoracic space. Once the liver is identified and an adequate window is obtained, the probe is adjusted so that the US beam includes the vertebral bodies medially, the moving diaphragm cranially, and the right kidney caudally. In the supine patient, ascites can be visualized as an anechoic region separating the liver and kidney. A right pleural effusion can be visualized as an anechoic region cephalad to the diaphragm, allowing for the thoracic spine to be seen cephalad to the diaphragm (positive spine sign).

Advanced User. The RUQ view is possibly the most versatile and useful view in POCUS. Focusing above the diaphragm for pulmonary pathology, this view is the most sensitive for identifying early pulmonary congestion (B-lines), provides clues to the size and nature of pleural effusions, and frequently detects pneumonias involving the right lower lobe, which is poorly visualized on standard AP chest x-rays. The position of the diaphragm can be noted, as well as its movement with respiration. In the abdomen, in addition to free fluid, one also can evaluate for urinary obstruction and hydronephrosis, and abnormalities in size and echogenicity of the kidney and liver may provide clues to their dysfunction and chronicity. One can assess for hepatomegaly by sliding the probe caudally to visualize the position of the liver tip. By fanning the beam just anteriorly from the vertebral bodies, the IVC and occasionally the aorta can be visualized if gas obscures the view from the epigastric position. By continuing to fan anteriorly, one often can localize the position of the gallbladder and visualize gallstones.

LUQ

Beginner User. With the probe in the abdominal preset and the probe marker pointing toward the patient's head, the probe is placed around the sixth or seventh intercostal space in the posterior axillary line, with the probe face pointing medially toward the patient's spine. Unlike the liver, the spleen serves as a much smaller window and is surrounded by gas-filled structures, making it more challenging to find. Once the spleen is identified and an adequate window is obtained, the probe is adjusted so that the US beam includes the vertebral bodies medially, the moving diaphragm cranially, and the left kidney caudally. In the supine patient, ascites can be visualized as an anechoic region surrounding the spleen, most often in the region just beneath the diaphragm. As on the right, a left pleural effusion can be visualized as an anechoic region cephalad to the diaphragm with a positive spine sign.

Advanced User. The pulmonary applications of the LUQ view are the same as in the RUQ. In the abdomen, as on the right, one also can evaluate for urinary obstruction and hydronephrosis on the left. One can assess for splenomegaly with better sensitivity than traditional techniques by measuring the spleen along its long axis or by sliding the probe along the mid- or posterior axillary line to visualize position of the spleen tip.[20] Normally the stomach contains a large amount of air artifact and is poorly visualized. A fluid-filled stomach may be seen just anterior to the spleen and, in the presence of vomiting, suggests gastroparesis, small bowel, or gastric outlet obstruction. This can clarify the diagnosis in cases of cryptogenic nausea and vomiting.

Suprapubic

Beginner User. With the probe in the abdominal preset, and the probe marker pointing toward the patient's head, the probe is placed just above the symphysis pubis, with the probe face pointing into the pelvis. Because a fluid-filled bladder serves as the acoustic window, this view can be challenging when the bladder is mostly empty. Once the bladder is identified and an adequate window is obtained, the probe is adjusted so that the US beam cuts through the midline of bladder in its long axis. In women, the uterus can be seen posterior to the bladder, and in men the prostate can be seen posteriorly and caudally. In the supine patient, ascites can be visualized as an anechoic region surrounding the bladder, tracking posterior to the bladder in men and often posterior to the uterus in women. Unlike fluid contained in vessels, cysts, or organs, free pelvic fluid will tend to fill in crevasses, giving the appearance of anechoic "pointy" edges.

Advanced User. Mastery of the suprapubic view for ascites is necessary for an accurate assessment in clinic patients unable to rise from a wheelchair or climb onto an examination table. Assessing bladder volume can be measured, but often it is estimated visually with experience. This view helps uncover patients with unsuspected urinary retention, clarify unexpected bladder scan measurements, avoid unnecessary bladder catheterizations, check the position of malfunctioning urinary catheters, and provides early feedback on a patient's response to fluid challenges in renal failure. Bladder cancer can be detected as exophytic or pedunculated irregularities in the bladder wall, and prostate or uterine size also can be assessed.

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