Ascites is a condition often seen by GI
nurses. It is an accumulation of fluid in the abdominal cavity. The name
comes from a Greek word, "askos," which means bag or sack. The exact
mechanisms in the formation of ascites are unclear. It can be the result
of hepatic or non-hepatic causes.
In the United States, cirrhosis is by
far the most common cause of ascites, accounting for approximately 85
percent of all cases. Most liver disease in our country is related to
alcohol, so most patients with ascites are alcoholics. Malignancies,
heart disease, tuberculosis, dialysis and other disorders account for
the remainder of cases.
Patient History
Diagnosing ascites should include a few
key points. The patient’s history is crucial and should incorporate
questions directed at intake of alcohol. Daily consumption of
approximately 80 grams of ethanol for a time period of 10 to 20 years is
necessary for the development of cirrhosis. This equals eight beers, a
liter of wine or eight ounces of hard liquor. As many of us have
witnessed, people often understate their alcohol intake, so careful
questioning is crucial.
Weight is becoming increasingly more
important in the formation of liver disease. It may be possible that as
the tendency toward obesity in the United States continues, nonalcoholic
steatohepatitis (NASH) will overtake alcohol as the primary cause of
cirrhosis. This is an inflammation of the liver as a result of an
accumulation of fat. As well as weight, diabetes and hyperlipidemia
contribute to NASH. NASH may be suspected in a patient with cirrhosis
with no other obvious cause.
Along with alcohol use and NASH,
chronic Hepatitis C is a common cause of cirrhosis. The patient should
be questioned about risk factors, such as blood transfusions, substance
abuse, tattoos and acupuncture, dialysis, or birth in a region known for
high rates of Hepatitis C.
Cirrhosis from unknown causes is termed
"cryptogenic." With a detailed patient history and specific lab testing,
the incidence of cryptogenic cirrhosis is dropping.
Ascites can also be caused by
malignancies. Major sources are peritoneal carcinomatosis, breast,
colon, lung and pancreatic cancers. A small percentage of people with
ascites have more than one cause, and this makes diagnosis that much
more difficult.
Physical Findings
Certain physical findings are
associated with ascites. Abdominal girth is a clue, but this is not
specific to ascites; it can also be increased by bowel distention,
tumors or other sources.
A test called the ‘puddle sign’ can
detect as little as 120 ml of ascitic fluid. The patient lies prone for
several minutes, then rises to the hands and knees. A stethoscope is
placed on the most dependent portion of the abdomen. As the stethoscope
is moved across the abdomen away from the examiner, a finger is flicked
against the abdomen. Increasing loudness at the edge of the ‘puddle’
suggests the presence of ascites. This can be a difficult position for
some patients to maintain.
Another test, for "shifting dullness,"
can also be used, but is not very sensitive in overweight patients. The
patient lies in a supine position. The examiner percusses from the
tympanic bowel downward to a line of dullness, and this line is marked.
The patient then turns to one side, and the examiner again percusses and
remarks the line of dullness. A significant shift in the line suggests
toe presence of at least 500 ml of ascitic fluid.
Large amounts of fluid are necessary
for a "fluid wave" to be present. One examiner presses on the patient’s
abdomen vertically at the midline. A second examiner taps the flank
sharply with one hand while palpating the opposite side. If ascites is
present, the second examiner will feel the impulse of the tapping with
the other hand.
Ultrasound is also useful in detecting
the presence of ascitic fluid. CT scans can also do this, but they come
with the risks of X-ray exposure and reaction to dye. Additionally,
ultrasounds may be more cost effective.
Paracentesis
The gold standard for diagnosing
ascites is abdominal paracentesis. Generally, the patient is lying on
the back with the head of the bed slightly elevated. A needle of
sufficient length to penetrate through the abdominal wall is used. Areas
with scar tissue should be avoided due to possible adhesions. The lower
left quadrant is the site used most frequently. If there are multiple
scars, ultrasound can be used to determine an appropriate site.
A "Z" technique is used to seal off any
leakage of fluid after the needle has been removed. The skin is pulled
downward while the needle is inserted, and released once ascitic fluid
is flowing.
Lab tests performed with the initial
paracentesis should include cell count, albumin, and total protein at a
minimum. Other tests may be done as indicated by the patient’s history.
Additionally, the overall appearance of the fluid can be useful.
Uncomplicated ascites fluid is
generally clear yellow. Blood may indicate trauma during the needle
insertion, or it may be a sign of malignancy. Ascitic fluid that is
infected will be cloudy. Milky (chylous) fluid most often indicates the
presence of triglycerides. Elevated serum bilirubin levels will cause a
brownish coloration. Fluid that is dark brown may mean a biliary
perforation, ruptured gall bladder or perforated duodenal ulcer.
Ascitic fluid for cell count is
collected in a purple-top tube with EDTA, an anticoagulant, to prevent
clotting. WBC and PMN (neutrophil) counts are usually the most important
data from cell counts.
Close to the time of paracentesis, a
serum albumin should be obtained. Ideally, the specimens should be
obtained within an hour of each other. Along with the ascitic fluid
albumin level, the serum–to ascites albumin gradient (SAAG) is
calculated. The ascitic fluid albumin level is subtracted from the serum
level. If the difference, or gradient, is greater than 1/1g/dL, portal
hypertension is present.
A smaller gradient can almost certainly
exclude the possibility of portal hypertension. Causes of low SAAG
ascites include peritoneal carcinomatosis, TB, dialysis,
surgically-caused ascites and cardiac disease.
Ascitic Fluid Infections
Culturing of ascitic fluid is commonly
done whenever infection is suspected. Keep in mind that signs of ascites
fluid infections can be very subtle, so cultures may be indicated even
for very mild or questionable symptoms. Cirrhotic patients are more
prone to infections due to immune system defects. Blood culture bottles
should be prepared and filled at the bedside for the best results.
Infected ascitic fluid can fall into one of five types.
Spontaneous bacterial peritonitis (SBP)
has a positive culture and an elevated PMN count. These patients should
also have no identifiable source of infection that could be treated
surgically. Monomicrobial nonneutrocytic bacterascites (MNB) is
distinguished by a fluid culture that is positive for only one organism,
and has a decreased PMN count, as well as no source of infection that
could be surgically treated.
Culture-negative neutrocytic ascites (CNNA)
will have negative cultures, but elevated PMN count. The PMN count must
be determined before any antibiotics have been given for proper
classification as CNNA. CNNA may actually be SBP, but with poor results
from the ascitic fluid culture for whatever reason. These three types of
ascitic fluid infections are spontaneous.
Additionally, infections can be
classified as secondary bacterial peritonitis. This diagnosis is made
with a culture that is positive for more than one organism, the PMN
count is elevated, and there is an identifiable surgically treatable
source of infection. This category may require emergency surgery. The
remaining type of ascitic fluid infection is most often caused by a
traumatic paracentesis, with bowel bacteria leaking into the peritoneal
cavity, and is not often seen. Polymicrobial bacterascites is marked by
positive cultures for more than one organism and a low PMN count.
A newer development that is being
studied is the use of bedside reagent strips (dipsticks), which may
reduce the time for positively diagnosing infected ascitic fluid.
In addition to infections of ascitic
fluid, other complications include cellulitis, tense ascites (which
should be treated immediately with therapeutic paracentesis), pleural
effusion (if the effusion is large in a cirrhotic patient, this is
referred to as hepatic hydrothorax; this may be the result of a
diaphragmatic defect) and abdominal wall hernias.
Treatment of Ascites
Treatment of ascites depends on the
cause. Of those with low SAAG ascites, the most common cause is
peritoneal carcinomatosis. If the malignancy is ovarian, surgical
debulking of the tumor and chemotherapy may be beneficial. If the cause
is other than ovarian, life expectancy is short and treatment may be
limited to therapeutic paracentesis. Diuretics for these patients may
only serve to reduce circulating volume and not reduce the volume of
ascitic fluid. Other low-SAAG types of ascites may be cured by dealing
with the underlying cause.
Infected ascitic fluid should be
treated with appropriate antibiotic therapy. If there is an identified
source that is surgically treatable, emergency surgery may be indicated.
High-SAAG ascites is almost always
caused by cirrhosis. If the patient is alcoholic, ascites may actually
be resolved, or at least become more responsive to treatment, if alcohol
intake is stopped. With many patients, however, this may not be
possible. Education on a diet low in sodium, for the patient and whoever
may be preparing food, will be vital. Fluid restrictions at home are not
likely to be successful. Diuretics may be helpful to reduce the volume
of ascitic fluid. Therapeutic paracentesis is beneficial.
Older wisdom dictated that only limited
volumes of ascitic fluid be removed at any one time, for the fear of
hemodynamic instability. Newer knowledge has replaced this; many liters
of ascitic fluid can be safely taken off. Additionally, paracentesis can
be repeated as ascites fluid reaccumulates.
TIPS (transjugular intrahepatic
portosystemic shunt) is a procedure usually done under local anesthetic
that can help reduce ascites that does not respond to diuretics. A stent
is placed in the liver between the portal vein and a hepatic vein to
enhance blood flow and reduce pressure. This procedure is performed in
interventional radiology.
Prognosis of Cirrhotic Patients
The prognosis of patients with
cirrhosis can be determined by using the Child-Pugh scoring system.
Points are assigned based on serum bilirubin and albumin levels, INR,
presence and degree of ascites, and presence and degree of
encephalopathy. The points are totaled; the larger the total (as in
Class C, representing the highest total), the lower the life expectancy.
Conclusion
Ascites can be the result of a variety
of causes. As GI nurses, many of the patients we see will have cirrhosis
as the cause. Patient history and careful specimen collection are
fundamental to diagnosing and treating this population.
Terry Markiewicz is a staff nurse in
the Bruggeman Center Endoscopy Unit at Ellis Hospital in Schenectady,
N.Y.
