Introduction

Gallstone ileus is a mechanical intestinal obstruction due to migration of a gallstone through a cholecystoenteric fistula. It is an uncommon complication of cholelithiasis¹ occurring in 0.3 to 1.5% of patients with cholelithiasis and accounts for 1 to 4% of mechanical bowel obstructions in the general population and up to 25% in those > 65 years^2,3. Management of gallstone ileus involves surgery, either by treating the bowel obstruction with enterolithotomy and enterorrhaphy alone or bowel resection with or without anastomosis. In some cases, manual expulsion of the gallstone may be used. Surgical timing (either on an emergency or delayed basis) for treating the cholecystoenteric fistula is controversial^2-5.

Morbidity varies according to the different series up to 50%, and mortality ranges between 12 and 27%. These elevated figures are possibly related to patients’ age group and associated comorbidities^3,4. The aim of this work was to describe the preoperative, intraoperative and postoperative variables of a case series of gallstone ileus and evaluate the incidence of recurrent gallstone ileus.

Material and methods

We conducted an observational and retrospective cohort study using a prospective database of emergency surgeries at a tertiary referral center. Patients undergoing surgery with a diagnosis of acute abdomen due to bowel obstruction between January 2009 and December 2021 were analyzed. Bowel obstruction was defined as abdominal distension, nausea, vomiting, crampy abdominal pain and absence of bowel movements (absence of gas and stool passage). Patients with a diagnosis of gallstone ileus were included in the analysis. The diagnostic imaging tests performed were abdominal ultrasound and computed tomography (CT) scan of the abdomen, The diagnosis of gallstone ileus was confirmed by distended bowel loops (with transition point from distended to collapsed distal bowel), presence of ectopic gallstone, and pneumobilia. These signs constitute the Rigler triad⁶. Three approaches were used: midline laparotomy, ultrasound-guided laparotomy and laparoscopy. In patients undergoing ultrasound-guided laparotomy, an ultrasound scan was performed in the operating room to identify the ectopic gallstone and the incision site was marked on the abdominal wall. Previously, these patients underwent a CT scan of the abdomen to rule out the presence of a second stone in the bowel. One-stage procedure was defined as treatment of bowel obstruction and cholecystoenteric fistula repair within the same surgical procedure. The twostage management consisted of treating the bowel obstruction during emergency surgery and deferring cholecystectomy to a second stage in case biliary complications or recurrence of gallstone ileus occurred. Treatment of bowel obstruction was based on the following surgical strategies: enterotomy with stone removal and enterorrhaphy; bowel resection and anastomosis; or manual expulsion of gallstone from the small bowel to the colon through the ileocecal valve without enterotomy. Patients with duodenal obstruction (Bouveret’s syndrome) were managed with antrum and pylorus incision, gallstone extraction and simple suture. The demographic, perioperative, intraoperative and postoperative variables were analyzed. Complications were categorized using the Clavien-Dindo classification⁷. The study was conducted following the recommendations of the Declaration of Helsinki and the rules of the local Committee on Ethics, ensuring the confidentiality of the information. An informed consent was not required due to the retrospective design of the study.

Results

During the study period, 667 patients were admitted to the emergency department with symptoms of bowel obstruction. Of these, 564 (84.5%) underwent surgery, and 21 (3.1%) were diagnosed with gallstone ileus. These patients constituted the population analyzed in the present study (Fig. 1). Median age was 63 years and 80% were women. Sixty-six percent had a history of symptomatic cholelithiasis, 45% had previous abdominal surgeries and up to 38% had one associated comorbidity or greater (Table 1).

All the patients underwent ultrasound while a CT scan was performed in 16 of them. Rigler triad was observed in 56% on CT scan (Fig. 2) and in 30% on ultrasound; however, when two out of three criteria were considered as diagnosis, the figure increased to 80% and 52%, respectively.

Operative time was 95 minutes. In 28% of patients a laparotomy was performed under ultrasound guidance. Only a 74-year-old female patient, who had been approached through laparoscopy, required conversion due to the impossibility of removing a gallstone with a size of 5 × 4 cm gallstone located in the duodenum (Bouveret’s syndrome); this patient required incision of the anthrum and pylorus, gallstone removal and simple suture.

Twenty patients (95.2%) underwent surgery only to solve the bowel obstruction. Only one patient underwent a one-stage procedure due to a perforation of the gallbladder fundus associated with bowel obstruction (Table 2).

The terminal ileum was the most common site of obstruction and enterolithotomy with enterorrhaphy was the most common surgical procedure. Two patients required bowel resection and anastomosis due to bowel perforation with associated peritonitis. Manual expulsion of gallstone was used in only one patient. Mean gallstone size was 2.5 cm and in 85.7% of cases only one gallstone was found. A patient treated with bowel resection and anastomosis developed anastomotic leak and required an ileostomy due to generalized peritonitis and critical condition. This patient was readmitted 6 months later due to acute cholecystitis requiring cholecystectomy, treatment of the cholecystoenteric fistula and closure of the ileostomy during the same surgical procedure.

Mean hospital length of stay was 10.2 days (interquartile range: 3 - 62). Nineteen percent required admission to the intensive care unit and the readmission rate was 9.5%. Morbidity of the series was 38% and mortality was 0% (Table 3).

Discussion

In the present case series, gallstone ileus accounted for 3% of mechanical bowel obstructions, in agreement with the literature (1 to 5%)^1,8-12. Halabi et al.¹³ reported an incidence of 0.095% among 3,452,000 cases of bowel obstructions. They suggested that, despite life expectancy has increased, the greater number of cholecystectomies performed earlier could explain the lower incidence of gallstone ileus. Median age of our patients was 63 years, which is lower than the one reported in other series where the population is > 70 years, and most patients were women^12-15. The associated comorbidities were similar to those reported by other authors¹³. In addition, 47% of patients had a history of previous surgeries. Rigler triad (pneumobilia, bowel obstruction and ectopic radio-opaque gallstone)⁶ is characteristic of gallstone ileus, but the three criteria are only present in 14 to 53% of the cases^16-18. Computed tomography scan of the abdomen and pelvis has a sensitivity of 90-93%, a specificity of 100% and a positive predictive value of 99% for the diagnosis of gallstone ileus, and can identify Rigler triad, gallstone location and evaluate the anatomy of cholecystoenteric fistulas¹⁹. Another advantage of CT scan is its ability to detect complications of gallstone ileus (intestinal edema, inflammation, and ischemia)²⁰. The preoperative diagnosis in our study was 100%, and all our patients (21) underwent ultrasonography while CT scans were performed in only 16. In the remaining 5 patients the surgeon decided not to perform a CT scan because of the clear clinical picture and ultrasound findings. Most series reported lower figures varying from 50 to 79%^15,16,21. This difference could be due to the high-resolution imaging techniques currently available and to the small number of cases in our series. Two of the three diagnostic criteria were present in 50% of the patients evaluated by ultrasound and in 80% of those undergoing CT scan.

The appropriate surgical treatment is controversial, and there are three alternatives available: solving the bowel obstruction alone without treating the gallstone disease, treatment of both conditions (bowel obstruction and gallstone disease) in a one-stage procedure or treating the obstruction and scheduling the cholecystectomy within 4-6 weeks¹³.

The first option, which prioritizes treating the obstruction, is one of the most used and is a valid alternative in elder patients with comorbidities and clinical and metabolic impairment. The potential problem is that complications as cholecystitis, cholangitis, recurrence of gallstone ileus or gallbladder cancer may develop if the gallstone disease is not treated. The one-stage approach would be recommended only for patients with good clinical condition and for surgical teams with experience in complex gallstone disease.

The third therapeutic option (treating the obstruction in an acute setting and deferring surgery for gallstone disease) would seem to be the ideal situation; however, patients should be closely monitored, and as in the second option, they should be treated by surgeons with experience in complex gallstone disease. Only one patient required a one-stage procedure to treat both the obstruction and the cholecystoenteric fistula due to an additional gallstone complication (perforated gangrenous gallbladder). This patient had many complications (postoperative ileus and surgical site infection) and prolonged length of hospital stay^3,4.

The surgical approach is also not free of controversy, as one can choose between laparotomy, laparoscopy or hand-assisted laparoscopic surgery. Hand-assisted laparoscopic surgery is a combined technique and is currently one of the surgical options most widely used²². Its primary target is to identify the level of obstruction or ectopic gallstone by laparoscopy and then perform a mini-laparotomy to exteriorize the loop and perform enterolithotomy plus enterorraphy. Although the conversion rate reported by most publications is 50%, the work published by Moberg et al.²³ reported conversion in only 2 of 19 patients, and in the article by Alfredo Ríos²² only 1 of 20 patients required conversion. The greatest difficulties of this technique are how to manage the distended bowel and identify the level of obstruction.

Ultrasoundguided laparotomy, used in 28% of our cases, seems to be a good option. This minimally invasive technique does not require staff trained in laparoscopic surgery for bowel obstruction and avoids large incisions with a high possibility of complications of the abdominal wall. However, there are no comparative studies to draw conclusions. Only one patient was approached by laparoscopy because the laparoscopy tower was not available 24 hours a day and the emergency department surgeons had no experience in the laparoscopic management of bowel obstruction. In one patient the gallstone was pushed forward manually from the jejunum to the colon, thus avoiding visceral opening and its potential complications. The surgeon preferred this therapeutic option based on the normal size of the colon (without abnormal narrowing) and the small size of the stone which easily passed through the ileocecal valve. The site of obstruction is mainly related to the gallstone size. In our patients, gallstones were mainly found in the ileum, in agreement with what has been described in the literature¹³. Two patients had upper bowel obstruction^2,24 due to large stones, while two others had obstruction at the level of the colon (diverticulosis)²⁵.

Morbidity rate was 38%, similar to the one reported in the current literature. Mortality rate is usually high, but none of the patients in our series died. This could be due to the fact that we treated the bowel obstruction alone in 95% of the cases, a situation that reduces mortality, as most of the large case series published have reported^3,13.

Recurrent gallstone ileus has been described in up to 40% of cases as Martin-Perez et al. have reported¹². In our study, the incidence was 4.7% and occurred within 6 months, in agreement with that reported by Reisner et al.³.

One of the issues that remains to be defined is the adequate treatment of gallstone disease, due to its potential complications. Only 2 patients developed these complications. One patient presented with cholecystitis that required cholecystectomy 6 months after bowel obstruction, and another patient developed recurrent gallstone ileus, which was treated with enterotomy and enterorrhaphy. The rates of complications in our patients are lower than those reported in the literature³; however, this could be due to difficulties in long-term follow-up because of the poor adherence to treatment in our population.

Timely treatment of patients with symptomatic cholelithiasis would significantly decrease the incidence of gallstone ileus as Halabi et al.¹³ have reported, avoiding the high morbidity and mortality associated with this condition and its management. However, access to quality of care, particularly in low-income populations, sometimes hinders fulfillment of this objective.

The weaknesses of our study are its retrospective nature, the lack of availability of endoscopic and laparoscopic services 24 hours a day, and the difficulties in the long-term follow-up of patients. In conclusion, gallstone ileus is a rare cause of mechanical obstruction. An accurate preoperative diagnosis, mainly by CT scan, and an appropriate surgical treatment are crucial. The approach and management depend on surgeon’s experience and patient’s general status, so the potential benefits and complications of the treatment must be evaluated on an individual basis.