Diagnostic ultrasound ( PDFDrive )

612 PART II Abdominal and Pelvic Sonography
Drainage Procedure
Ater the drainage catheter is placed, the cavity is completely
aspirated and gently irrigated. Care should be taken not to distend
the cavity during the irrigation because this may increase the
risk of bacteremia. Repeat images are obtained to determine the
size of the residual cavity, the position of the drainage tube, and
whether the entire abscess communicates with the drainage tube.
If the abscess cavity has not completely resolved, the drainage
catheter may need to be repositioned, or a second drain may
need to be placed. Such manipulations are oten performed under
luoroscopy the day ater initial drain placement. Correct catheter
position and adequate catheter size are the most important factors
for successful drainage.
Follow-Up Care
All drains must be irrigated regularly. Injection and aspiration
of 10 mL of isotonic sterile saline three or four times daily is
usually suicient. If drainage is especially tenacious or the abscess
is large, more frequent irrigations with greater volumes of saline
may be necessary. he lu id collection can be drained dependently
or by low, intermittent suction. he character and volume of the
output should be recorded each nursing shit and checked daily
on rounds by the radiology service. If the drainage changes
signiicantly in volume or character or if fever recurs, the patient
should be reexamined to check for istulas, catheter blockage,
reaccumulation of the abscess, or a previously undiagnosed
collection.
From 24 to 48 hours ater tube placement, a sinogram may
be performed to look at the abscess cavity size, completeness of
drainage, and catheter position and to look for istulas. Simple
abscess cavities may drain for 5 to 10 days. Abscesses secondary
to istulas from bowel, biliary, or urinary tracts may drain for 6
weeks or longer. Follow-up sinograms can be performed as
clinically indicated based on collection complexity and amount
and character of drainage. Many patients can be cared for on an
outpatient basis once stable.
Catheter Removal
he three criteria for catheter removal are as follows:
1. Negligible drainage over 24 hours
2. Afebrile patient
3. Minimal residual cavity
Drains in small, supericial abscess cavities can be pulled all
at once, whereas drains in large, deeper cavities may be gradually
removed over a few days, which promotes healing by secondary
intention.
Abdominal and Pelvic Abscesses: General
Most abdominal and pelvic abscesses are secondary to underlying
bowel disease or seen ater surgery. Percutaneous abscess
drainage for postoperative abdominal abscesses has become
the accepted primary treatment of choice, with cure being
the expected goal. Percutaneous drainage has also played a
principal role in the treatment of diverticular, appendiceal,
and Crohn disease–related abscesses. 125-127 Drainage of
abscesses in these acutely ill patients can help alleviate sepsis
and allow the necessary curative surgery to be performed on an
elective basis.
Drainage of abdominal abscesses is oten best performed
with CT guidance, which allows the best visualization and avoids
adjacent bowel loops. CT also provides an overview of the entire
abdomen, to ensure all collections are drained. Ultrasound can
provide excellent guidance for percutaneous abscess drainage;
however, careful review of CT imaging assists in planning an
optimal approach free of intervening bowel. Unlike CT, ultrasound
is especially valuable in the treatment of critically ill patients
who cannot be transported to the radiology department.
Pelvic abscesses are of variable origin and have been notoriously
diicult to access because of their deep location, overlying
bowel, blood vessels, and urinary bladder. Traditional approaches
include an anterior transperitoneal approach or a posterior
transgluteal approach. he transgluteal approach is relatively
painful, and care must be taken to avoid the sciatic nerve. Small,
deep pelvic abscesses may be diicult to access safely using
traditional approaches.
Ultrasound-guided transvaginal drainage has been established
as a viable alternative to these traditional approaches 128,129 (Fig.
17.17). Needle guides are available for endovaginal probes that
help guide the needle into the luid collection (Videos 17.6 and
17.7). his transvaginal approach can be used to drain tuboovarian
abscesses unresponsive to medical treatment. he trocar
technique may also be used successfully for transvaginal drain
placement. Transrectal ultrasound-guided drainage has also been
described in the drainage of pelvic luid collections, 130 but such
an approach is infrequently used.
For nonpurulent pelvic collections, immediate catheter
drainage is not necessarily indicated. Many of these patients
respond to a one-step aspiration, lavage, and antibiotic therapy
based on results of cultures of the aspirates. 131,132
Enteric abscesses oten have communication with the GI
tract. For these abscesses to be drained successfully, the GI
communication irst must be recognized, then allowed to heal
and close before removal of the catheter. Fistulas will not close
if there is distal obstruction, tumor, or persistent infection.
Even with the most aggressive techniques, however, success in
treating abscesses with enteric communication is lower than
for noncommunicating abscesses. 133,134 A particular challenge
exists in the percutaneous treatment of Crohn disease–related
abscesses. Obviating surgery in the short term can only
be achieved in about 50% of patients, with a much lower
success rate in patients with preexisting bowel istulas. 127,135
Enterocutaneous istulas may develop along the drain tract in
these patients.
Speciic Anatomic Applications
Liver
In addition to antibiotics, percutaneous aspiration or drainage
should be considered as a primary treatment for most pyogenic
liver abscesses (Fig. 17.18). Pyogenic liver abscesses are most
oten caused by (1) hematogenous seeding from intestinal sources,
such as appendicitis or diverticulitis; (2) direct extension from
cholecystitis or cholangitis (Fig. 17.19); or (3) surgery or trauma.