Dropped Gall Stone

Clinical History

Small abscess secondary to a dropped gallstone from past laparoscopic cholecystectomy

Imaging Findings

A 55 year old patient presented to his primary physician for intermittent mild right upper quadrant pain and mild grade of fever for one month. He denied any nausea, vomiting, diarrhea or jaundice. His past medical history was not significant except for history of laparoscopic cholecystectomy one year ago. Physical examination was unremarkable except some tenderness in the right side of abdomen in the subhepatic region and temperature of 100⁰ F. Results of standard laboratory tests were normal, except for mildly elevated leukocyte count of 13.0 x 1000 cells/UL (differential count, 80 % neutrophils, 10% lymphocytes and 6% monocytes). Contrast CT scan of the abdomen showed small inflammatory mass in right subhepatic region (arrowheads) with a small high density focus in the center. This high density focus was not seen on his precholecystectomy CT scan done one year ago for the abdominal pain. Ultrasound and CT scan that time had demonstrated multiples stones in the gallbladder. Review of the cholecystectomy intraoperative records revealed bile spillage into abdominal cavity during gallbladder handling. Considering these facts, diagnosis of small abscess secondary to dropped gallstone was made, the small high density focus on CT scan representing dropped gallstone. Patient improved after a course of antibiotics and is symptom free for last 6 months.

Discussion

Laparoscopic cholecystectomy has become the treatment of choice for symptomatic gallstones due to an overall decrease in complication rate, quicker healing, shorter hospital stays, and improved patient satisfaction. Gall stone spillage during laparoscopic cholecystectomy is common and occurs more frequently than open surgery. Some series quote a range of 6 % to 30 %. Spillage of stones can occur during dissection of the gall bladder off the liver bed, tearing with grasping forceps, or during extraction of the gall bladder through one of the port sites. The incidence is more common when operating on acutely inflamed, friable gallbladder. Although the dropped gallstone is most likely to remain in the subhepatic space, the peritoneal insufflation and irrigation used during laparoscopic cholecystectomy may facilitate migration of a dropped gallstone to a remote location. Inflammatory reactions induced by the gallstone can lead to erosion of the diaphragm, the peritoneal membrane, and other natural boundaries. There are case reports of gallstones discovered in hernia sacs, abdominal wall incision sites, within a thoracic empyema, and even in urine and sputum. In majority of cases the dropped gallstone causes no problem. Complications occur in only about 0.3 % of patients. The most common complication associated with dropped gallstone is abscess formation. Inflammatory masses, fistulous communications, and adhesion formation are also reported findings. A wide range of symptoms have been associated with dropped gallstones including nausea/vomiting, hematuria, and dyspareunia. Presentation may occur many years after cholecystectomy, with reports of patients presenting between 4 days after cholecystectomy and up to 10 and 20 years following surgery. Complications are more often associated with bilirubinate pigment stones as these stones commonly harbor and protect viable bacteria. The diagnosis is often delayed due to unusual site of abscess formation and lack of awareness of stone spillage during previous cholecystectomy. Radiologist should consider dropped stones as a potential source of recurrent abscess in any patient presenting months or years after laparoscopic cholecystectomy. The ultrasound, CT and MRI are valuable as diagnostic tools. Radioopaque gallstones may be visualized on CT scan within an abscess or inflammatory mass. Radiolucent stones may not be observed on CT. Ultrasound may demonstrate these radiolucent stones within an abscess as echogenic shadowing foci. MRI shows stones as foci of T1 hypointensity. Treatment involves removal of the causative stone via percutaneous or open techniques. Prevention remains the most important consideration. Assiduous dissection technique, the use of bags for gallbladder extraction, and diligent search and removal of dropped gallstones in the event of perforation can help prevent complications from occurring. As the incidence of complications from dropped gallstones remains low, conversion from laparoscopic to open cholecystectomy due to dropped gallstones, without other factors, is not recommended.

Differential Diagnosis List

Final Diagnosis

Small abscess secondary to dropped gallstone

URL:	https://www.eurorad.org/case/5807
DOI:	10.1594/EURORAD/CASE.5807
ISSN:	1563-4086