Imaging diagnosis of two unusual forms of gallstone ileus

Abstract

Ileus from an impacted gallstone in the duodenum or any other part of intestine is a rare complication of cholelithiasis. When a gallstone impacted in the distal stomach or in the duodenum, it is called Bouveret's syndrome, a rare form of gallstone ileus.1 Small bowel ileus caused by gallstone has become more and more common recently due to popular usage of computed tomography (CT) and magnetic resonance imaging (MRI). In the past, imaging diagnosis relied primarily on conventional radiography and contrast-enhanced fluoroscopy.1 CT has subsequently been shown to be quite useful for this diagnosis.2,3 Recently, MR cholangiopancreatography (MRCP) has emerged as a valuable noninvasive technique for evaluation of biliary disease. Here we described the CT, MRCP and gastroenterography findings in two patients with unusual form of gallstone ileus (GI), one is Bouveret's syndrome and the other is negative gallstone-induced ileus. Few reports about GI with angiografin and MRCP findings of Bouveret's syndrome has been published.3–8 CASE REPORT Medical history Case 1 A 78-year-old woman with a history of 5 years of chronic cholecystolithiasis presented with a 2-day history of vomiting, and inability to have oral intake beyond small sips of water, followed by abdominal distention. The patient was afebrile and denied experiencing hematemesis or melena. He denied abdominal pain and anus stopping aerofluxus and defecation. Vital signs were stable, and physical examination demonstrated only choloplania. Pertinently positive laboratory values included elevated white blood cell count of 11.3×109/L and serum bilirubin level of 33.9 μmol/L. CT, MRCP and gastroenterography with angiografin were obtained. Case 2 A 80-year-old man with a history of 7-year of chronic gastritis and cholecystolithiasis presented to the emergency department with a 3-day history of abdominal colic pain radiated to back and a 2-day history of nausea and vomitting. The patient was admitted from the emergency department for evaluation of small bowel obstruction. Vital signs were stable, and physical examination demonstrated only mild tenderness in the right upper quadrant. Pertinently positive laboratory values included elevated white blood cell count of 13 × 109/L and alanine aminotransferase of 226 U/L; pertinently negative laboratory values were normal troponin, bilirubin (total and direct), and CT scan from diaphragma to articulation of pubis was obtained twice: first one was obtained at 30 minutes after the patient taking 200 ml of 33.5% angiografin. Second scan was obtained 7 hours later. Imaging findings Case 1 Abdominal contrast-enhanced CT demonstrated the pneumobilia with a thickened, enhancing gallbladder wall (approximately 0.5 cm) and filling defects. MRCP demonstrated a orbicular-ovate filling defect with cocenric citcle signal in the descendent duodenum (Fig. 1). A fistula between collapsing gallbladder and duodenal bulb was demonstrated (Fig. 2) and intrahepatic bile duct and bile commen duct with small filling defect at its inferior extremity was seen. Gastroenterography with angiografin demonstrated a orbicular-ovate filling defect in the descendant duodenum with a maximal diameter of approximate 3.8–4.5 cm. Intrahepatic bile duct and bile commen duct with small filling defect at its inferior extremity was visualized. The differential diagnosis of gastric outlet obstruction includes gallstone ileus, tumors, perforated peptic ulcer disease, pancreatitis, and malignant fistula. After aggregating analysis, we diagnosed it as Bouveret's syndrome, a special type of gallstone ileus.Fig. 1.: Bouveret syndrome. MRCP coronal thin slice scan shows the orbicular-ovate filling defect in the descendant duodenum which has a sign of cocenric citcle signal (arrow), consistent with a large gallstone.Fig. 2.: Bouveret syndrome. Transection scan shows a fistula (arrowhead) between collapsing gallbladder (narrow arrow) and duodenal bulb (wide arrow).Case 2 The patient was examined by CT for evaluation of small bowel obstruction. CT scan from diaphragma to articulation of pubis was obtained twice: the first was performed 30 minutes after the patient taking 200 ml of 33.5% angiografin, the CT transection images and the reconstruction including Slip Thin Slice Maximum Intensity Projection (STS-MIP) and Multiple Planar Reconstruction (MPR) showed the obstruction point was at the juncture of jejunoileum with regional intestinal wall enhancing. But we could not identify the reason responsible for the ileus because of the low density of intestinal liquid (Fig. 3). Another sign was that the gallbladder could not be identified because it collapsed. Second examination was obtained 7 hours after first scan. The filling defects was demonstrated as round isoattenuating lesion at the juncture of jejunoileum because of high density background (Fig. 4).Fig. 3.: MPR showed that the site of obstruction (arrow).Fig. 4.: MPR showed the cause of obstruction is a low density lesion (arrow) because of high density background.Pathologic evaluation and clinical course Case 1 A percutaneous cholecystostomy was performed to alleviate the biliary obstructive symptoms. The patient subsequently developed a small bowel obstruction with the stone at the jejunum after 3 days, as demonstrated at abdominal CT. She was taken to the operating room for an enterotomy and gallstone extraction. The patient's condition deteriorated after the surgery, and died 17 days later. Case 2 The patient discharged the stone from anus after oral intake another 100 ml 67% angiografin. The stone was a round light lesion like a pigeon egg, with the center of low density at -220 HU on CT scan. From analysis, it was speculated that the patient must have a fistula between gallbladder and duodenum, so we suggested the patient to be examined by endoscopic retrograde cholangiopancreatography (ERCP). The ERCP confirmed that there was a fistula. Because the patient was very old and got better after treatment for 5 days, so the surgery was not performed. DISCUSSION Gallstone-induced ileus is a rare complication of cholelithiasis, and gastric outlet obstruction is even more rare.1 Bouveret syndrome is a gastric outlet obstruction produced by a gallstone in the duodenum. It was described by Leon Bouveret in 1896 and occurs most commonly in elderly women with a mean age of 68.6 years.1,2 The term of classic gallstone ileus often refers to an obstructing stone localized to the terminal ileum. A duodenal location accounts for only 2%-3% of cases.2 Gallstone ileus occurs in 15% of patients with a biliary-enteric fistula.3 The presenting clinical situation is variable and nonspecific but often includes nausea, vomiting, and epigastric pain at first. Laboratory studies may indicate an obstructive pattern with increased bilirubin.4 In the past, the diagnosis usually had been made by endoscopy, but CT and MRCP are becoming more useful for the diagnosis.4 Early diagnosis is important because mortality is historically high at 33%, though it has decreased to 12% in recent years.1,2 The high mortality may be related to the advanced age of the typical patient as well as other comorbidities or disease resistance is relatively weak. The decrease in mortality in recent years likely represents the impact of endoscopic treatment options in place of surgery as well as early diagnosis with noninvasive imaging, such as CT and MRI. The diagnosis of approximately 30%-35% of gallstone ileus may be suggested on the hypothesis of the clinical presentation and the Rigler triad in CT: bowel obstruction, pneumobilia, and an ectopic gallstone.4,5 Ultrasound imaging may also suggest the diagnosis but often present a confusing diagnostic picture. Although the gallstone will be sufficiently large to be seen by ultrasound imaging, it may be difficult to distinguish a duodenal location from an orthotopic location with a contracted gallbladder wall. If the fistulous tract is filled with fluid or air, the fistula may also be seen but can be confused with the common duct.3 In case 1, gastroenterography with angiografin identified the fistulous tract and a filling defect which refers to gallstone. This kind of method has not been reported before. We performed the gastroenterography with angiografin because the the patient could only drink a little fluid and barium was considered too thick to be taken in. The fistula tract had just been enlarged by the gallstone, so the contrast material filled it easily. And when MRCP was performed, the fluid in the stomach and proximal duodenum could not get through the gallstone easily, so the fluid filled the fistula tract, making it easily identified by MRCP. In the case 2, we have already identified the site of obstruction through tracing dilated intestinal canal, but could not identify the cause because without contrast at that part of intestine. When the contrast material get through, high density background formed, so the negative gallstone at the obstruction point was identified. Classic gallstone ileus has the sign of the Rigler triad, including pneumobilia, ileus and allotopia gallstone.3 Pneumobilia and a dilated stomach or intestine are easily identified. We can also show the direct sign: fistula. The fistula may be seen if the tract is enhanced by positive oral or air contrast material, such as the case 1. A secondary sign that may be useful is the identification of oral contrast material within the gallbladder.3 The gallstone is usually apparent in the duodenum but is low density or isoattenuating to bile and fluid in 15%—25% of cases,3 such as the case 2. So, oral administration contrast material improves diagnosis by surrounding the gallstone and therefore would increase the sensitivity of CT. There is another advantage that oral administration contrast material such as angiografin can abate edema of intestinal wall and lubricate the enteric cavity, so can promote discharging relatively small gallstone, such as the case 2. Recently, Pickhardt et al4 described the use of MRCP for diagnosis of Bouveret syndrome with isoattenuating stones, and this may be especially true in a patient unable to tolerate oral contrast material. But it may be difficult to identify the gallstone in the distal small bowel by MRCP. Endoscopy is preferred as a therapeutic option because removal may be performed with mechanical, electrohydraulic, or laser lithotripsy.7 Surgery often is not desirable as the patients are often poor surgical candidates secondary to concomitant illnesses and advanced age. If surgery is performed, enterolithotomy alone may be adequate treatment in the elderly, and subsequent cholecystectomy may not be required.3 However, as in this two cases, the patient 1 underwent the enterolithotomy and died of many kind of complications. And the patient 2 recovered soon after the gallstone discharged without surgery. In summary, timely diagnosis of gallstone ileus with imaging is possible and important. The diagnosis may be made with gastroenterography and MRCP, but CT and ERCP are likely the most sensitive diagnosis and ERCP has additional advantage of therapeutic options. MRCP appears to be reserved for Bouveret syndrome with identifying fistula. CT with oral contrast material appears to be useful for a minority of cases with isoattenuating stones. And another value of oral contrast material such as angiografin is that it may promote discharging gallstone. Although early diagnosis may aid in rapid extraction of an obstructing stone, mortality remains relatively high, likely secondary to the typical patient's advanced age and morbid conditions and impact from surgical intervention.