Peter C. Nauka; MD1; Benjamin T. Galen, MD2
(1)
Albert Einstein College of Medicine and Montefiore Medical Center, Department
of Internal Medicine, Residency Training Program, Bronx, NY, USA.
(2)
Albert Einstein College of Medicine and Montefiore Medical Center, Department
of Internal Medicine, Division of Hospital Medicine, Bronx, NY, USA.
Download article PDF – POCUS Journal 2020; 5(2):42-45.
Abstract
Malignant effusions occur frequently in patients with cancer and
are important to diagnose and treat. In this report, we describe a novel point-of-care
ultrasound (POCUS) protocol to rapidly identify pleural effusion, pericardial
effusion, and ascites: The Focused Assessment with Sonography in Cancer (FASC).
This protocol utilizes six standard sonographic positions to identify the
presence of fluid in common anatomic spaces. The FASC examination is intended
for widespread use by oncologists and other clinicians who treat patients with
cancer.
Introduction
Clinicians in oncology,
emergency medicine, hospital medicine, and primary care frequently encounter
patients with cancer who develop fluid accumulation in the pleural,
pericardial, abdominal, and pelvic spaces. Both solid tumor metastases and
hematologic malignancies have the potential to cause third spacing of
intravascular fluids via seeding to and disruption of serosal membranes and
normal endothelium [1,2]. We propose a Focused Assessment with Sonography in
Cancer (FASC) examination using point-of-care ultrasound (POCUS) to enable all
clinicians to routinely and rapidly assess patients for pleural effusion,
pericardial effusion, and ascites. Similar to other POCUS protocols like the
Focused Assessment with Sonography in Trauma (FAST) examination, the FASC
examination uses six views to detect fluid (Figure 1) [3,4].
Third-space fluid
accumulation leads to a range of symptoms for patients with cancer that can
significantly reduce quality of life [3-5]. Life-threatening
complications, such as cardiac tamponade from a rapidly accumulating
pericardial effusion, are important to detect expediently. Monitoring for
recurrence of fluid accumulation in the pleural, pericardial, abdominal, and
pelvic spaces is important in longitudinal outpatient care. Palliative
procedures, such as intermittent drainage and indwelling catheters can decrease
symptom burden from malignant exudates. The potential benefit for FASC
examination is to diagnose and track fluid accumulation easily at the bedside
or in the office, using POCUS as an adjunct to physical examination.
POCUS is a portable,
low-cost, and increasingly popular imaging modality in widespread use by many
clinicians, but not yet by oncologists and hematologists [6]. The use of POCUS
in identifying fluid accumulation in potential spaces has been very
well-established [7]. This modality is well tolerated by patients and has
excellent sensitivity and specificity compared to computerized tomography
imaging (Table 1) [8-10].
Table 1. Test characteristics of Point-of-Care Ultrasound (POCUS)
in finding fluid. The diagnosis of pleural effusion and ascites
were compared to computerized tomography imaging. Sensitivity and specificity
for pericardial effusion were determined by comparing image interpretation by
non-cardiologists to echocardiography boarded cardiologists (9, 10).
|
Point-of-Care
Ultrasound |
|||
|
Sensitivity |
Specificity |
||
|
Pleural Effusion |
Visualization
of effusion |
93% |
96% |
|
Ascites |
Visualization
of fluid |
96% |
82% |
|
Pericardial Effusion |
Visualization
of fluid |
96% |
98% |
FASC
Examination
Setup
and Patient Positioning
The goal of the FASC
examination should be explained to the patient and family. Reassurance should
be offered that the FASC examination is not painful and does not use ionizing
radiation. For the FASC examination, the patient should be placed in the
supine or semi-recumbent position. The patient should place both hands
comfortably behind the head; this can improve visualization through the intercostal
spaces [11]. Flexion of the hips and knees will relax abdominal muscles for
optimal windows [11].
Depending on availability,
either a phased array probe (typically 2 Mhz – 7.4 Mhz) or curvilinear
transducer probe (2 – 5 Mhz) can be used for the entire FASC examination.
Users should be familiar with basic adjustments on their machine, such as gain
and depth. In conventional probe orientation for POCUS, the probe
indicator is placed towards the patient’s right or towards the head, except for
the subxiphoid cardiac view, which uses cardiology orientation (indicator to
patient’s left).
Position
1 and 4. Detecting Pleural Effusions and Ascites in the Upper Abdominal
Quadrants
The ultrasound probe should
initially be placed in the mid-axillary line at the level of the xiphoid
process with the indicator towards the patient’s head. The diaphragm should be
visualized along with the liver in position 1 and the spleen in position 4
(Figure 1). In addition, the kidneys and thoracic spine should be
identified in the abdomen. This usually requires sliding up and down between
ribs spaces, sweeping the probe posteriorly, and tilting in the
anterior-posterior plane. The thoracic spine can be identified because
ultrasound waves reflect of bone, creating the hyperechoic appearance of the
vertebral bodies with anechoic shadows deep to them. With the probe in the
mid-axillary line, the vertebral column can be identified at the bottom of the
screen. Normal aerated lung does not provide an acoustic window to visualize
any deeper structures, thus the spine is only seen when there is pathology at
the lung base, such as a pleural effusion. Visualization of the thoracic spine
above the diaphragm is referred to as the “spine sign,” which confirms that
pathology (such as pleural effusion) is not an artifact. The absence of a
pleural effusion is often noted by a positive “lung curtain sign,” in which
pleural sliding and A-lines are seen at the lung base during inspiration
[12]. When present, a pleural effusion is anechoic (black) and if large
enough will lead to atelectasis of the nearby lung (Figure 2, Supplementary
Video 1, 2). Loculations can be present in highly exudative pleural
fluid. It is important to identify the thoracic spine posterior to pleural
effusions (positive “spine sign”) to rule out artifact [13]. Rib
artifacts and reflection across the diaphragm can lead to hypoechoic and
anechoic findings above the diaphragm, but these will not have a positive spine
sign.
In the supine position,
ascites collects in the dependent locations, such as the sub-diaphragmatic
space (Figure 2). Sliding the probe inferiorly from the diaphragm level
when in position 1 and 4 allows for identification of the hepatorenal recess
(Morrison’s pouch) and splenorenal recess, respectively. This fluid will be
detected by its anechoic (black) appearance on ultrasound and requires correct
identification of nearby structures. A fluid filled stomach, loops of
bowel, or renal cysts can mimic ascites.
Position
2 and 5. Detecting Ascites in the lower abdominal quadrants
The probe is placed on the
right lower or left lower abdominal quadrants and should be tilted anterior to
posterior and rocked cranial to caudad to visualize positions 2 and 5
(Supplementary Video 3, 4). In abdominal carcinomatosis, ascites might be
loculated with hyper-echoic (white) strands in the anechoic (black)
fluid.
Position
3. Subxiphoid Cardiac Window to Detect Pericardial Effusion
Pericardial effusions are
common in patients with cancer and can lead to cardiac tamponade, particularly
if the fluid accumulates rapidly [14]. The subxiphoid cardiac view is ideal for
assessing the presence or absence of pericardial effusion (Figure 2,
Supplementary Video 5). The probe should be placed inferior to the xiphoid
process with the indicator pointed to the patient’s left (cardiology
orientation). Care should be taken not to apply excessive pressure.
The ultrasound probe is rocked to the patient’s left, using the liver as an
acoustic window to view the heart and pericardial space. When present, a
pericardial effusion is anechoic (black), but can have echogenic loculations or
fibrin strands [11]. Some pericardial effusions are mobile and collect in
dependent areas based on positioning [11]. Assessing for cardiac tamponade
physiology is a more advanced POCUS skill: new, symptomatic, or large
pericardial effusions in patients with cancer found on FASC examination should
prompt referral for further evaluation.
Position
6. Pelvic view to detect ascites
The pelvis is another dependent area where ascites can be
visualized. The probe is placed superior to the pubic symphysis and pointed
inferiorly and posteriorly with the indicator to patient’s right (Supplementary
Video 6). The probe can be tilted anteriorly to posteriorly and rocked left to
right to improve visualization. It is important to identify the bladder so that
urine is not mistaken for ascites. Ascites, when present, can be visualized
anterior to, posterior to, or lateral to the bladder.
Conclusions
Pleural effusions,
pericardial effusions, and ascites are commonly diagnosed in patients with
cancer. POCUS is a useful adjunct to the physical examination in detecting,
monitoring, and draining these effusions. While POCUS is not currently in
widespread use by oncologists, trainees are increasingly learning POCUS in
medical school and internal medicine residency [15-21]. The FASC protocol
contains views that are easily obtained and have been validated for use by
clinicians in many other specialties. We anticipate that oncologists will find
learning and independently performing the FASC protocol very rewarding. The
FASC examination might allow oncologists to monitor their patients in clinic
and in the hospital for fluid accumulation. For oncologists who are not
trained in POCUS, there are many opportunities to learn POCUS in the continuing
medical education setting. Emergency medical providers, hospitalists, and
primary care providers currently using POCUS can easily incorporate the FASC
examination into their practice [22-24]. Further work is necessary to
determine the right amount of training to competently perform the FASC
examination.
