AJR 2004; 182:1203-1205
© American Roentgen Ray Society
CT Identification of Abscesses After Dropped Appendicoliths During Laparoscopic Appendectomy
Newrhee Kim1,
William P. Reed, Jr.2,
Maher A. Abbas3 and
Douglas S. Katz1
1 Department of Radiology, Winthrop-University Hospital, 259 First St., Mineola,
NY, 11501.
2 Department of Surgery, Winthrop-University Hospital, Mineola, NY 11501.
3 Department of Surgery, Kaiser Permanente, 4760 Sunset Blvd., Los Angeles, CA
90027.
Received August 19, 2003;
accepted after revision September 23, 2003.
Address correspondence to D. S. Katz
(dsk2928{at}pol.net).
Introduction
Appendicitis is a common disorder that affects approximately 7% of the
United States population during their lifetime
[1]. Urgent appendectomy
remains the treatment of choice for most patients with acute appendicitis, and
laparoscopic appendectomy has been increasingly used as the surgical approach
[2]. Reports have emerged
[3,
4] of gallstones that were
retained or "dropped" at laparoscopy and that acted as nidi of
infection with subsequent abscess formation in cases of acute cholecystitis,
another common surgical condition for which laparoscopy has become the
standard surgical procedure. Such a complication is relatively rare but is now
well recognized, and the corresponding CT findings have also been reported
[4]. Dropped appendicoliths at
open (i.e., conventional) appendectomy
[5] or at laparoscopic
appendectomy [6,
7] with associated
postoperative abscess have rarely been reported in the surgical literature.
However, the CT finding of an abscess associated with a dropped appendicolith
would be diagnostic if the appendicolith was calcified enough to be identified
on a preoperative CT examination. We report the case of a patient who
developed a pelvic abscess caused by appendicoliths that were accidentally
dropped in the pelvis during laparoscopic appendectomy.
Case Report
A 38-year-old previously healthy man presented to our emergency department
complaining of a 2-day history of colicky abdominal pain, fever, chills,
nausea, vomiting, and increasing abdominal girth. Findings of physical
examination and laboratory studies were consistent with a diagnosis of
appendicitis. CT of the abdomen and pelvis performed using oral and IV
contrast media confirmed acute appendicitis. Two appendicoliths were
identified in the lumen of the appendix near its base
(Fig. 1A). The patient then
underwent laparoscopic appendectomy, and a perforated appendix was identified
and removed. The mid portion of the appendix was gangrenous, with a fecalith
protruding through it, but the operating surgeon believed that the appendix
was removed in its entirety, including the appendicoliths. The patient,
afebrile and with normal WBC, was discharged from the hospital after 5
days.
The patient returned approximately 17 days later complaining of lower
abdominal pain, fever, and dysuria. Findings of physical examination and
laboratory studies suggested an infection. A new CT scan of the abdomen and
pelvis showed a 5-cm abscess in the cul-de-sac containing two calcifications
consistent with dropped appendicoliths (Figs.
1B and
1C) and a left-sided pelvic
abscess (not shown).
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Fig. 1B. —38-year-old man with acute appendicitis. Contrast-enhanced CT
scan of pelvis obtained 17 days after appendectomy shows expected minimal
postoperative changes around appendectomy clips near cecum
(arrow).
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Fig. 1C. —38-year-old man with acute appendicitis. Contrast-enhanced CT
scan of pelvis obtained at lower level than seen in B shows collection
with wall enhancement (large arrows) consistent with abscesses and
containing two calcifications representing "dropped"
appendicoliths (small arrows) in more posterior collection.
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The patient was admitted, hydrated, and placed on IV antibiotics. A
laparoscopically guided drainage of the abscess was performed. The surgery
revealed erythema of the outer walls of the sigmoid colon and bladder, and the
abscesses seen on the CT scan were identified and drained. Two fecaliths were
found and removed from the posterior pelvic abscess, and an intraoperative
rectal examination was performed to assist in emptying the abscess. The
patient was discharged several days later in stable condition, afebrile and
with normal WBC.
Discussion
Appendectomy remains the standard treatment for acute appendicitis. A
laparoscopic approach has become increasingly common in recent years because
it offers several potential advantages over the traditional open approach.
Prospective studies have shown that laparoscopic appendectomy patients have
less pain, faster recovery time after surgery, better cosmetic results, and a
somewhat lower rate of wound infection. The adoption of laparoscopic
appendectomy is not yet universal
[1,
5], although laparoscopic
procedures are now generally used for cholecystectomy. Some controversy
continues about the appropriateness of laparoscopic appendectomy in certain
situations, especially in perforated appendicitis
[1].
Our patient's complication—dropped appendicoliths associated with
abscess formation—can be compared with the similar complication
associated with gallstones dropped during a cholecystectomy for acute
cholecystitis associated with intraabdominal abscess. The laparoscopic
approach for cholecystectomy carries a small but increased risk of
postoperative infection caused by dropped gallstones. The infection may
present after some delay, in some instances up to several years after surgery
[4,
6], because bacteria may be
chronically harbored in gallstones
[3]. The incidence of
gallbladder perforation has been estimated at 15–30% during laparoscopic
cholecystectomy for acute cholecystitis
[6]. Perforation is
particularly likely to lead to gallstones being dropped into the peritoneal
cavity during surgery, and retrieving them can be difficult. It is estimated
that gallstones are dropped during as many as 10% of laparoscopic
cholecystectomies. An abscess may ultimately occur in 0.6% of all laparoscopic
cholecystectomy patients [3],
although this percentage is difficult to verify. It is reasonable to assume
that most, if not all, dropped appendicoliths are also potentially infectious
[6].
Cross-sectional imaging techniques can show the presence of gallstones or
fragments of stones in an abscess in a patient who has undergone prior
cholecystectomy [4]. Abscesses
related to dropped gallstones are generally found in the subhepatic space, but
they may occur anywhere in the abdomen and even in the thorax as a result of
fistulization of the stone [3,
4]. The identification on CT of
a calcification in an abdominal or pelvic fluid collection in a patient with a
history of appendectomy should also be diagnostic of such abscesses
[6,
7].
When laparoscopic appendectomy becomes a more common procedure, the
complications related to it will probably become more common also. To our
knowledge, only 10 cases have been reported of dropped appendicoliths that
caused abscesses after open appendectomy
[5,
6]. Only three cases involved
laparoscopic appendectomy. Two of those were reported in the surgical
literature
[6–8].
In two patients, a contained perforation of the appendix was initially
identified at surgery; as with our patient, in neither case did the surgeon
realize that an appendicolith had been dropped
[6,
7]. In both patients, CT scans
showed a subhepatic abscess that contained a calcification. Initial
percutaneous abscess drainage failed in both patients, and both required
surgical removal of the remaining abscess and the associated appendicolith (by
open surgery in one and laparoscopic surgery in the other)
[6,
7].
Dropped stones from laparoscopic appendectomy are rare, but the radiologist
and surgeon should consider them as a potential source of an intraabdominal
abscess [7]. Because the
latency time to develop an abscess from dropped gallstones is variable,
2–3 years or longer, and because these abscesses can occur in locations
remote from the surgical site
[7], it is possible that a
similar scenario might occur with a dropped appendicolith, although our
patient developed an abscess rather quickly, approximately 2 weeks after
hospital discharge, and the other recently reported patients also presented
within 3–6 weeks after their initial appendectomy
[6,
7]. However, radiologists
should consider dropped appendicoliths a theoretical possibility even in
patients in whom the surgical history is remote, because misdiagnosing this
type of abscess as a simple abscess or even as a necrotic or mucin-producing
tumor may delay appropriate treatment
[3,
4]. As is the case with dropped
gallstone–related abscess, the nidus of infection—the
appendicolith—must be removed as soon as identified to prevent
recurrence
[3–7].
Typically, this removal would be effected at repeated surgery, as in our
patient, via a laparoscopic approach. A single case of percutaneous removal of
a dropped appendicolith was recently reported
[8], similar to the report of
percutaneous removal of dropped gallstones and drainage of the associated
abscess [6].
In conclusion, we alert the radiologic community that just as abscesses may
develop after gallstones are dropped during laparoscopic cholecystectomy, a
similar scenario, albeit rare, can also occur after laparoscopic appendectomy.
When an appendix is discovered to be gangrenous at surgery, it should be
manipulated gently to avoid dropping any appendicoliths, and an attempt should
be made to retrieve any appendicoliths that spill
[6]. Radiologists should also
communicate to the surgeon the presence of any appendicoliths identified on CT
scans obtained in patients with suspected appendicitis. Our patient's appendix
might have been perforated before surgery, so it is possible that he could
have developed abscesses in any event. Prospective identification of the
appendicoliths on the postoperative CT would have altered patient treatment
because instead of performing percutaneous abscess drainage after the first
surgery, we performed a second laparoscopic surgery.
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