DOI:10.2214/AJR.04.1371
AJR 2005; 185:1159-1165
© American Roentgen Ray Society
Role of Helical CT in Diagnosis of Gallstone Ileus and Related Conditions
Francesco Lassandro1,
Stefania Romano1,
Alfonso Ragozzino1,
Giovanni Rossi2,
Tullio Valente2,
Ilaria Ferrara3,
Lugia Romano1 and
Roberto Grassi3
1 Department of Diagnostic Imaging, A. Cardarelli Hospital, Viale Cardarelli 9,
Naples 80131, Italy.
2 Department of Radiology, A. Monaldi Hospital, Naples, Italy.
3 Institute of Radiology, Second University of Naples, Naples, Italy.
Received August 31, 2004;
revised November 23, 2004;
Address correspondence to S. Romano
(stefromano{at}libero.it).
Abstract
OBJECTIVE. Small-bowel obstruction from gallstone impaction is a
pathological entity frequently observed in elderly patients with a history of
cholelithiasis or cholecystitis. Diagnostic imaging plays a great role in the
management of patients with suspected gallstone ileus and overall in the
correct predictive diagnosis: in the last years, some experiences in
radiologic diagnosis of this entity by sonography, abdominal plain film and
CT, and occasionally MRI have been reported. Some questions related to
gallstone ileus are to be considered: one of them is the possibility of
recurrence, which increases the operatory risk in these patients. Recurrence
may be due either to the presence of overlooked stones that were already in
the bowel at the time of surgery but not identified and not removed or to the
migration of other stones in patients not previously cholcystectomized. In
cases of acute abdomen, establishing an effective conservative therapy may be
a critical point. The aim of this retrospective study was to evaluate the
capabilities of helical single-detector and MDCT scanners to allow a correct
diagnosis of this disease.
CONCLUSION. Helical single-detector and MDCT may improve the
diagnosis of gallstone ileus, providing important information regarding the
exact number, size, and location of ectopic stones and the site of intestinal
obstruction or direct visualization of a biliary–enteric fistula, to
help clinicians in the therapeutic management of patients.
Introduction
Small-bowel obstruction is a daily occurrence in all emergency departments.
Radiologists are frequently asked about the cause of a mechanical occlusion,
and CT has become the best diagnostic technique for imaging emergency patients
[1]. The main cause of
intestinal obstruction is adhesions; however, some uncommon entities may
represent an interesting theme to investigate. One of them is the gallstone
ileus, a mechanical intestinal obstruction caused by impaction of gallstones
in the lumen of the bowel, which was first described by Bartholin in 1654
[2]. The main problem related
to this disorder is its frequency in elderly persons, which seems to increase
to 25% of all nonstrangulated intestinal obstructions
[3]. Patients often present
with a history of cholelithiasis or cholecystitis; women are more commonly
affected than men [3].
Gallstone ileus has a high mortality rate, ranging from 8% to 30%
[3–5];
other concomitant diseases may increase the operative risk in patients older
than 65 years. Diagnostic imaging plays an important role in the management of
patients with suspected gallstone ileus; some authors have recently reported
their experience in the radiologic diagnosis of this entity on sonography,
abdominal radiography, CT, and occasionally MRI
[6–9].
Some questions related to gallstone ileus must be considered. One is the
possibility of recurrence, which increases the surgical risk in these
patients. Recurrence may be due either to the presence of overlooked stones
that were already in the bowel at the time of surgery but not identified and
removed, or to the migration of other stones in patients who have not
previously undergone cholecystectomy
[3,
10–12].
In patients with an acute abdomen, the establishment of an effective
conservative therapy may be critical. In these patients with no findings of
mechanical ileus, CT may increase the detection of stones not yet impacted
[13]. Finally, the surgical
treatment of these patients is a challenge, especially because of the
possibility of a laparoscopic enterolithotomy or a one-stage procedure of
fistula repair and cholecystectomy, to reduce the risk of complications and to
decrease the high postoperative mortality rate
[14,
15].
The aim of this retrospective study was to evaluate the possibilities of
helical CT and especially of the new generation of MDCT scanners to allow a
correct diagnosis of gallstone ileus in patients with acute abdominal pain and
to provide more accurate information to clinicians for surgical treatment.
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Fig. 3B —87-year-old man with recurrent gallstone ileus (patient 8).
Axial CT scan allows visualization of cholecystenteric fistula (straight
arrow) and persistence of residual stone in gallbladder (curved
arrow).
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Fig. 3D —87-year-old man with recurrent gallstone ileus (patient 8).
Axial CT scan obtained at same time as C shows no evidence of stones in
gallbladder; however, cholecystenteric fistula (arrow) is still
detectable.
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Materials and Methods
We retrospectively reviewed 40 charts of consecutive patients from February
1998 to May 2004 (six men, 34 women; age range, 57–98 years; mean age,
72 years) with a proven surgical diagnosis of gallstone ileus who underwent CT
before surgery. We considered for our study the first CT examination performed
at the time of admission to the emergency department of two institutions (A.
Cardarelli Hospital and Second University of Naples). Review of all the image
series was made by experienced radiologists. Helical single-detector Picker
PQ5000 (22 patients from February 1998 to March 2002) and 4-MDCT GE LightSpeed
Plus (18 patients from April 2002 to May 2004) scanners were used. All
examinations were performed before and after the administration of IV contrast
medium. Unenhanced imaging was used to allow an easier localization of
calcifications inside the loops, and contrast-enhanced images were used to
evaluate the intestinal wall and areas of altered density in other abdominal
structures. One hundred twenty milliliters of iodinated (370 mg I/mL) nonionic
contrast medium was administered at the flow rate of 2.5 mL/sec; the delay
until acquisition was 70 sec. No endoluminal contrast medium was administered
because the fluid and gas inherent in the bowel allowed sufficient evaluation
of the intestinal loops. Parameters of acquisition were, for helical
single-detector sequences, 4-mm thickness and 4-mm reconstruction interval;
for 4-MDCT sequences, 3-mm thickness and 2-mm reconstruction interval with
possibility to reconstruct from the native acquisition at 1.25 mm. Multiplanar
image reformations (maximum intensity projection, multiplanar reconstruction,
3D) were obtained using dedicated workstations. The image review looked for
evidence of small-bowel obstruction (evidence of mechanical ileus: fluid
overdistention of the loops above the impacted stones and collapsed loops
downstream) or nonobstructing ileus (acute symptoms of occlusion with
preserved intestinal transit); presence of an ectopic endoluminal stone, its
size and location; pneumobilia; direct visualization of biliary–enteric
fistulas; and recurrence of disease. After review of the images, related first
reports were revised to annotate any different, additional, or missed
findings.
Results
Intestinal obstructions were detected in 32 patients, pneumobilia in 35,
and air in the gallbladder in six (Fig.
1). In five patients, direct visualization of a
biliary–enteric fistula was noted (Figs.
2A,
2B,
2C and
3A,
3B,
3C,
3D,
3E)
(Table 1). In 35 patients,
correct location of the stone was made at the first report; in five patients
with partially calcified stone (12.5%), a retrospective review of the imaging
findings (bulging of the intestinal loop or endoluminal calcifications)
suggested their locations. In five patients, multiple endoluminal stones were
detected (Fig. 2A,
2B,
2C). In eight patients, the
evidence of pneumobilia and ectopic intestinal stones in the small bowel was
not associated with findings of mechanical ileus. One patient (2.5%) had
previously undergone cholecystectomy. Three cases of recurrence of gallstone
ileus were noted in patients who previously underwent enterolithotomy without
cholecystectomy. Diameter of the stones varied from 0.6 to 3.5 cm; the
smallest impacted stone had a maximum diameter of 2.5 cm and the largest, 3.5
cm. In patients with no evidence of intestinal obstruction, the smallest stone
size was 0.8 x 0.6 cm and the largest was 2.0 x 1.8 x 2.6
cm. In all patients at least two dimensions of the calculi were listed; in
some patients the third dimension was difficult to see because of a partially
calcified calculus or the presence of artifacts from patient movement.
However, in 18 patients in whom MDCT was performed, three dimensions were
obtained (Table 1).
In 25 patients, the stone was located in the ileum, and in 12, in the
jejunum (Figs. 2A,
2B,
2C,
3A,
3B,
3C,
3D,
3E,
4,
5,
6A,
6B). Visualization of three
cases of partially calcified stones was possible on only the coronal images
(Fig. 6B). In two patients,
there was evidence of multiple stones in the ileum; in three additional
patients, multiple stones were evident in the jejunum. In these patients,
pneumobilia was always evident, intestinal obstruction seen in three, a
biliary–enteric fistula was noted in two, and recurrence was seen in one
patient (Table 1). One patient
presented with an ectopic stone in the stomach, one in the duodenum
(Bouveret's syndrome), and one in the colon. Two patients who had undergone
surgery for gallstone ileus 9 months and 1 year before presented with
recurrence of the disease (one with a stone found in the colon). In two
patients with no findings of intestinal obstruction on the first emergency CT
performed for acute abdomen, the diagnosis of ectopic intestinal stone in the
jejunum was missed in the first report. These patients presented with
recurrence of symptoms of acute abdomen 3 days later and underwent surgery for
small-bowel obstruction. In the remaining 36 patients, the interval between
the onset of symptoms and admission to the hospital averaged 3–8 days.
Preoperative diagnosis based on clinical and CT findings was correct in 35
patients. Urgent laparotomy included enterolithotomy in all but one patient.
Postoperative complications were observed in one patient as a result of acute
pulmonary edema and sepsis.
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Fig. 6A —72-year-old woman with gallstone ileus (patient 3). CT scan
shows ectopic stone spontaneously passed through ileocecal valve after
subocclusive episodes (white arrow). Note also second stone in
jejunum (black arrow) that was overlooked in first report.
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Fig. 6B —72-year-old woman with gallstone ileus (patient 3). CT
coronal reconstruction shows second stone overlooked in first report
(arrows), which caused intestinal obstruction 3 days later. Air in
gallbladder (asterisk) is also seen.
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Discussion
Gallstone ileus is a complication in 0.3–0.5% of all cases of
cholelithiasis [2]; the ratio
of women to men affected ranges from 3:1 to 16:1
[3]. A recently acute biliary
episode frequently precedes the onset of gallstone ileus
[2]; the hypothesis is that
patients have subacute or chronic cholecystitis that leads to gallstone
erosion into the bowel.
The obstructing stone in gallstone ileus usually originates in the
gallbladder, although some cases of gallstone ileus have been reported in
which the gallbladder was absent, having been previously removed
[2]. In our study group, this
happened in only one patient (2.5%).
Intestinal obstruction results when the stone enters the gastrointestinal
tract, usually through a cholecystenteric fistula
[16] located between the
gallbladder and the duodenum
[2], and impacts in the
terminal ileum. In one of our patients (2.5%), the fistula was between the
cholecyst and the stomach. When a gallbladder filled with multiple stones
evacuates itself by erosion into the duodenum in which the lumen has been
compromised by spasm and induration, attempts to propel the partially impacted
larger stones may generate reverse peristalsis and a proximally located stone
may be expelled by projectile vomiting
[17]. Once in the intestinal
tract, a gallstone may be vomited, may pass spontaneously through the rectum,
or may impact and cause obstruction
[2]. The site of obstruction is
usually the terminal ileum because it is the narrowest portion of the small
bowel [2]; most of the stones
in our series were located in the ileum (25 cases, 62.5%). Three stones were
not detected on CT.
Fewer than half the stones entering the alimentary tract will cause
obstruction because many stones are excreted uneventfully in the stool
[2,
18]. In our study, in two
patients (5%) stones in the colon were removed at laparotomy without
intestinal resection by pushing them out through the anus. Most reports
indicate that stones smaller that 2.5 cm pass spontaneously, although smaller
stones have produced ileus and stones as large as 5 cm have passed
spontaneously [2].
Size and morphology are important parameters to consider; it is commonly
agreed that a gallstone must be at least 2.5 cm to cause an intestinal
obstruction. In a recently reported case, a 1.6-cm impacted stone in the ileum
was treated with conservative therapy and finally evacuated without
complications [19].
Generally, stones causing ileus are single, large, faceted
[17], and between 2 and 5 cm
in length; however, huge stones have been reported, as well as stones mixed in
type, elliptical, or barrel-shaped
[17]. When stones are impacted
in the ileum, it is important to be aware that additional stones may be
present in the proximal bowel
[17]. In our study, the
evidence of multiple stones was noted in five patients (12.5%); it is
important to correctly report stones located in the jejunum so that the
surgeon can search for them during the operation.
The role of diagnostic radiology in gallstone ileus is well known. From the
early experience on a few cases detected on conventional abdominal
radiography, in which air in the biliary tree and faintly calcified
gallstones—findings compatible with intestinal obstruction—were
reported [20], to the first
case detected on CT in 1983
[21], to recent studies using
conventional radiography, sonography, and CT
[8], the importance of a
correct preoperative diagnosis has been emphasized.
Although in some cases the triad of small-bowel obstruction, stone in the
bowel, and biliary gas is present and recognizable on conventional
radiographs, CT allows a correct diagnosis of gallstone ileus with higher
accuracy [8]. The information
obtained on CT is used to make a rapid diagnosis and aid in deciding whether
surgical or conservative treatment may be most effective
[19]. This approach may lead
to a decrease in the rather high morbidity and mortality rates seen in this
disease [22]. CT is useful
also for estimating the size of an impacted gallstone
[19,
23], especially at the
transition point between dilated and collapsed bowel
[24].
We believe MDCT may show important findings: the evidence of endoluminal
stones, their size in all orthogonal planes and their number. MDCT may also
detect ectopic stones and allow the diagnosis of gallstone ileus before severe
intestinal obstruction from stone impaction occurs. In our study, gallstone
ileus in 22 patients was detected on helical CT in 49 months (mean per month,
0.44 cases); however, MDCT allowed detection of 18 cases of gallstone ileus in
25 months (mean per month, 0.72 cases)—that is, more cases were
diagnosed in a shorter time.
Recurrent gallstone ileus is defined as a mechanical intestinal obstruction
secondary to occlusion of the intestine by an intraluminal biliary calculus
that was present but not obstructing at the time of a previous episode of
ileus, or secondary to the passage of new stones from a preexisting, not
surgically treated fistula
[10,
11]. This clinical entity has
been reported at a rate of 4.7%
[3]. Carefully searching for
more stones throughout the intestinal tract is important
[3] because multiple stones can
be expected in 3–44% of all patients with gallstone ileus
[3,
21,
25–28].
In our experience, three cases (7.5%) of recurrent disease were noted in
patients who previously underwent enterolithotomy without cholecystectomy,
which is in accordance with reports in the literature of a recurrent gallstone
ileus 1–6 months after enterotomy without cholecystectomy
[5,
10,
12].
Morphology has been thought to be predictive of recurring gallstone ileus
if the stones are cylindric or faceted
[29]. The importance of this
observation is that these shapes imply multiplicity of stones, which should
alert the surgeon to the possibility of remaining stones
[10]. However, we also believe
that with a rounded stone, measuring one diameter is enough, but with an
irregular calculus, all dimensions should be measured.
Newer MDCT scanners, using multiplanar or 3D volume-rendering
reconstructions, may allow better evaluation of the intestinal segment in
which the stone is impacted and its correct morphology, especially when axial
findings are indeterminate or doubtful, because the thinner collimation
creates isotropic data useful for the detection of small-bowel abnormalities.
Correct evaluation of the size is important because stones smaller than 2 cm
may not be innocuous; they may become larger by accretion as they descend the
intestinal canal and produce reflex spasm and volvulus
[17]. Most reports in the
literature are of just one size of impacted stone; however, in our experience
the size (in all three orthogonal planes) and number of all the stones
corresponded to pathologic findings in 28 of 40 cases. Moreover, in our study,
multiplanar visualization allowed the correct evidence of impacted stone in
three cases of partially calcified stones that were well seen on only the
coronal image.
In five patients in our study (not including patients with stones in the
stomach, duodenum, or colon), the evidence of pneumobilia and ectopic
intestinal stones was not associated with findings of mechanical ileus.
Because of promptly performed CT examinations, stones were detected in 35
patients at first report; in five other patients, only a retrospective
examination of the imaging findings suggested the presumed site of stones. To
our knowledge, possible gallstone ileus without evidence of intestinal
obstruction has been reported only once, in a description of six cases of
proven gallstone ileus in which abdominal radiography showed an unremarkable
pattern with a mild degree of nonspecific ileus
[20]. However, in that case
other findings that we detected on MDCT—pneumobilia and evidence of
ectopic stones—were not mentioned.
It is important to detect a stone that might cause ileus before evidence of
small-bowel obstruction because of the potential risk when elderly patients
undergo surgery. In cases of gallbladder ileus the prime objective is to
relieve the obstruction [15];
any delay in diagnosis and treatment may lead to serious complications such as
electrolyte imbalance, ischemic lesions, ulcerations of the bowel, abscess
formation, and, occasionally, free perforation and peritonitis
[20].
Regarding the one-stage surgical procedure—enterolithotomy plus
fistula repair and cholecystectomy—as the first choice of intervention
in gallstone ileus is controversial
[30,
31]. Proponents of the
one-stage procedure believe that it prevents future complications, including
cholecystitis, cholangitis, and recurrent gallstone ileus
[4]. Some authors have reported
a positive experience with this procedure and suggested that enterolithotomy
alone should be used for only unstable and difficult cases
[32]. However, other studies
have shown that complications occurred in 61.1–66.7% of patients
undergoing the one-stage operation and have suggested that the procedure be
reserved for selected patients at low risk with absolute indications of
obstruction [14,
15].
In our study, no patient underwent one-stage or laparoscopic procedures.
Direct CT visualization of the biliary–enteric fistula (reported in our
study in five patients, 12.5%) may help surgeons decide whether
cholecystectomy should be promptly performed in cases of large fistulas and
residual stones in the gallbladder. The early and prompt MDCT diagnosis of
endoluminal gallstones before the development of ileus may also help surgeons
plan the most effective treatment in these patients.
Gallstone ileus is a frequently misdiagnosed clinical entity. Better
awareness of this condition allows greater diagnostic accuracy and earlier
therapy and would avoid preoperative delay and unnecessary surgery in patients
in whom the stones pass spontaneously
[21].
In conclusion, CT examinations in patients with acute abdominal symptoms
may add more information to the typical imaging findings associated with
gallstone ileus. In addition to the Rigler radiologic triad (evidence of an
ectopic stone in the intestine, air in the biliary tree and gallbladder, and
small-bowel obstruction), CT allows detection of the exact location of the
ectopic stone and the site of obstruction and direct visualization of the
biliary–enteric fistula. These findings in patients admitted to the
emergency department for acute biliary colic will help clinicians in their
therapeutic management.
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Abstract
Introduction
