Role of Helical CT in Diagnosis of Gallstone Ileus and Related Conditions

Transcription

1 CT of Gallstone Ileus Gastrointestinal Imaging Clinical Observations Francesco Lassandro 1 Stefania Romano 1 Alfonso Ragozzino 1 Giovanni Rossi 2 Tullio Valente 2 Ilaria Ferrara 3 Lugia Romano 1 Roberto Grassi 3 Lassandro F, Romano S, Ragozzino A, et al. DOI: /AJR Received August 31, 2004; accepted after revision November 23, Department of Diagnostic Imaging, A. Cardarelli Hospital, Viale Cardarelli 9, Naples 80131, Italy. Address correspondence to S. Romano (stefromano@libero.it). 2 Department of Radiology, A. Monaldi Hospital, Naples, Italy. 3 Institute of Radiology, Second University of Naples, Naples, Italy. AJR 2005; 185: X/05/ American Roentgen Ray Society Role of Helical CT in Diagnosis of Gallstone Ileus and Related Conditions 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. mall-bowel obstruction is a daily S 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 AJR:185, November

2 Fig year-old woman with gallstone ileus (patient 30). CT scan shows air in gallbladder (arrow). Ectopic gallstone was found in ileum. A Fig year-old woman with gallstone ileus (patient 13). A, Axial MDCT image shows biliary enteric fistula (arrow). B, Volume-rendered axial CT scan shows ectopic, partially calcified stone (arrow); two other smaller calculi were also found. C, Volume-rendered sagittal CT scan shows third diameter of stone seen in B. B C 1160 AJR:185, November 2005

3 CT of Gallstone Ileus A C E Fig year-old man with recurrent gallstone ileus (patient 8). A, Axial CT image shows ectopic stone in jejunum (arrow). B, Axial CT scan allows visualization of cholecystenteric fistula (straight arrow) and persistence of residual stone in gallbladder (curved arrow). C, Axial CT scan 1 year later shows new stone (arrow) in sigmoid colon. D, Axial CT scan obtained at same time as C shows no evidence of stones in gallbladder; however, cholecystenteric fistula (arrow) is still detectable. E, Surgery confirmed presence of stone in sigmoid colon. B D AJR:185, November

4 ileus in patients with acute abdominal pain and to provide more accurate information to clinicians for surgical treatment. noted (Figs. 2 and 3) (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 Materials and Methods We retrospectively reviewed 40 charts of consecutive patients from February 1998 to May 2004 (six men, 34 women; age range, 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 TABLE 1: Location and Size of Ectopic Stones with Additional Imaging Findings Noted Retrospectively Patient No. Stone Size (cm) Location No. of Stones Other Findings Ileum 1 P a Ileum 1 MI, P Jejunum 2 P, AGB, MI Ileum 1 MI, P a Jejunum 2 MI, P Jejunum 3 P a Ileum 1 MI, P, BF, AGB a Jejunum 2 P, BF, R a Ileum 1 P, MI a Ileum 1 P, MI a Ileum 1 MI, P a Ileum 1 MI, P, AGB, BF a Ileum 3 P, BF, MI Jejunum 1 P a Ileum 1 P, MI a Jejunum 1 P, MI a Ileum 1 P, AGB, MI a Jejunum 1 P, MI a Ileum 1 P, MI a Ileum 1 P, MI Ileum 1 P a Ileum 1 P, MI a Jejunum 1 P, MI a Colon 1 P, R a Duodenum 1 AGB a Stomach 1 P, BF a Ileum 1 MI Jejunum 1 P, MI Ileum 1 P, MI Ileum 1 P, AGB, MI a Ileum 1 P, MI a Ileum 1 P, MI a Ileum 1 MI, P a Ileum 1 MI, P, R Jejunum 1 MI, P a Ileum 1 MI Ileum 1 MI a Ileum 1 MI a Jejunum 1 P, MI Jejunum 1 P, MI Note In case of multiple stones, only major stone size and site is reported. MI = mechanical ileus, P = pneumobilia, BF = biliary enteric fistula, AGB = air in gallbladder, R = recurrence. a Size confirmed on pathology AJR:185, November 2005

5 CT of Gallstone Ileus Fig year-old woman with gallstone ileus (patient 23). Axial CT scan shows ectopic stone in jejunum (arrow). their locations. In five patients, multiple endoluminal stones were detected (Fig. 2). 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 cm and the largest was 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. 2 6). 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. Fig year-old man with gallstone ileus (patient 28). Axial CT scan shows partially calcified ectopic stone in jejunum (arrow) that was overlooked in first report. Discussion Gallstone ileus is a complication in % 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, ellipti- AJR:185, November

6 cal, 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 smallbowel 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 A Fig year-old woman with gallstone ileus (patient 3). A, 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. B, 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. 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 previ- B ously 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 AJR:185, November 2005

7 CT of Gallstone Ileus 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 % of patients undergoing the onestage 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. 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