Methyl-tert-butyl-ether for treating bile duct stones: the British experience

Superior gallstone dissolubility and safety of tert-amyl ethyl ether over methyl-tertiary butyl ether

BACKGROUND

The use of methyl-tertiary butyl ether (MTBE) to dissolve gallstones has been limited due to concerns over its toxicity and the widespread recognition of the safety of laparoscopic cholecystectomy. The adverse effects of MTBE are largely attributed to its low boiling point, resulting in a tendency to evaporate. Therefore, if there is a material with a higher boiling point and similar or higher dissolubility than MTBE, it is expected to be an attractive alternative to MTBE.

AIM

To determine whether tert-amyl ethyl ether (TAEE), an MTBE analogue with a relatively higher boiling point (102 °C), could be used as an alternative to MTBE in terms of gallstone dissolubility and toxicity.

METHODS

The in vitro dissolubility of MTBE and TAEE was determined by measuring the dry weights of human gallstones at predetermined time intervals after placing them in glass containers with either of the two solvents. The in vivo dissolubility was determined by comparing the weights of solvent-treated gallstones and control (dimethyl sulfoxide)-treated gallstones, after the direct infusion of each solvent into the gallbladder in both hamster models with cholesterol and pigmented gallstones.

RESULTS

The in vitro results demonstrated a 24 h TAEE-dissolubility of 76.7%, 56.5% and 38.75% for cholesterol, mixed, and pigmented gallstones, respectively, which represented a 1.2-, 1.4-, and 1.3-fold increase in dissolubility compared to that of MTBE. In the in vitro experiment, the 24 h-dissolubility of TAEE was 71.7% and 63.0% for cholesterol and pigmented gallstones, respectively, which represented a 1.4- and 1.9-fold increase in dissolubility compared to that of MTBE. In addition, the results of the cell viability assay and western blot analysis indicated that TAEE had a lower toxicity towards gallbladder epithelial cells than MTBE.

CONCLUSION

We demonstrated that TAEE has higher gallstone dissolubility properties and safety than those of MTBE. As such, TAEE could present an attractive alternative to MTBE if our findings regarding its efficacy and safety can be consistently reproduced in further subclinical and clinical studies.

Efficacy and safety of a novel topical agent for gallstone dissolution: 2-methoxy-6-methylpyridine

BACKGROUND

Although methyl-tertiary butyl ether (MTBE) is the only clinical topical agent for gallstone dissolution, its use is limited by its side effects mostly arising from a relatively low boiling point (55 °C). In this study, we developed the gallstone-dissolving compound containing an aromatic moiety, named 2-methoxy-6-methylpyridine (MMP) with higher boiling point (156 °C), and compared its effectiveness and toxicities with MTBE.

METHODS

The dissolubility of MTBE and MMP in vitro was determined by placing human gallstones in glass containers with either solvent and, then, measuring their dry weights. Their dissolubility in vivo was determined by comparing the weights of solvent-treated gallstones and control (dimethyl sulfoxide)-treated gallstones, after directly injecting each solvent into the gallbladder in hamster models with cholesterol and pigmented gallstones.

RESULTS

In the in vitro dissolution test, MMP demonstrated statistically higher dissolubility than did MTBE for cholesterol and pigmented gallstones (88.2% vs. 65.7%, 50.8% vs. 29.0%, respectively; P < 0.05). In the in vivo experiments, MMP exhibited 59.0% and 54.3% dissolubility for cholesterol and pigmented gallstones, respectively, which were significantly higher than those of MTBE (50.0% and 32.0%, respectively; P < 0.05). The immunohistochemical stains of gallbladder specimens obtained from the MMP-treated hamsters demonstrated that MMP did not significantly increase the expression of cleaved caspase 9 or significantly decrease the expression of proliferation cell nuclear antigen.

CONCLUSIONS

This study demonstrated that MMP has better potential than does MTBE in dissolving gallstones, especially pigmented gallstones, while resulting in lesser toxicities.

Epidemiology, toxicokinetics, and health effects of methyl tert-butyl ether (MTBE)

This paper reviews the published information assessing the kinetics and potential for adverse health effects related to exposure to the fuel oxygenate, methyl tert-butyl ether (MTBE). Data were obtained from previously published reports, using human data where possible. If human data were not available, animal studies were cited. The kinetic profile of MTBE in humans is similar for ingestion and inhalation. The concentrations of MTBE to which the general public is expected to be exposed are orders of magnitude below concentrations that have caused adverse health effects in animals. Controlled human studies have not replicated early epidemiology studies that suggested, but did not confirm, a possible association between MTBE exposure and nonspecific health complaints.

Gallstone disease: Symptoms, diagnosis and endoscopic management of common bile duct stones

Bile duct stones (BDS) are often suspected on history and clinical examination alone but symptoms may be variable ranging from asymptomatic to complications such as biliary colic, pancreatitis, jaundice or cholangitis. The majority of BDS can be diagnosed by transabdominal ultrasound, computed tomography, endoscopic ultrasound or magnetic resonance cholangiography prior to endoscopic or laparoscopic removal. Approximately 90% of BDS can be removed following endoscopic retrograde cholangiography (ERC)+sphincterotomy. Most of the remaining stones can be removed using mechanical lithotripsy. Patients with uncorrected coagulopathies may be treated with ERC+pneumatic dilatation of the sphincter of Oddi. Shockwave lithotripsy (intraductal and extracorporeal) and laser lithotripsy have also been used to fragment large bile duct stones prior to endoscopic removal. The role of medical therapy in treatment of BDS is currently uncertain. This review focuses on the clinical presentation, investigation and current management of BDS.

Management of difficult common bile duct stones

More than 80% of all CBD stones can be effectively treated by endoscopic sphincterotomy and stone extraction using baskets or balloon catheters. For stones up to 2.5 cm in diameter, mechanical lithotripsy is the method of choice as a next step. Very large, impacted, or very hard concretions, however, often make mechanical lithotripsy cumbersome or even impossible. For these stones laser lithotripsy, EHL, and ESWL are nonoperative options, especially for elderly patients and patients with an elevated surgical risk. Because these methods are often only available at endoscopic centers, stenting is a treatment modality for immediate stone therapy, but as a definitive treatment it should be restricted to selected cases. ESWL, EHL, and laser lithotripsy yield similar success rates of 80% to 95% and may be used complementarily in endoscopic centers. ESWL is the preferred therapy in intrahepatic lithiasis. Laser lithotripsy shows the best results in CBD stones. Electrohydraulic lithotripsy is rarely used because of its high potential for tissue damage and bleeding. Laser lithotripsy using smart laser systems such as the rhodamine 6G dye laser and the FREDDY laser system can simplify the treatment of these difficult bile duct stones. The rhodamine 6G-dye laser allows blind fragmentation of these stones by exclusive insertion of a 7-F metal marked standard catheter into the bile duct by standard duodenoscopes using intermittent fluoroscopy. An oSTDS safely cuts off the laser pulse if contact with the stone is lost, thus preserving the bile duct from potential damage. Unfortunately the system is no longer produced. The new FREDDY laser lithotriptor with a piezoacoustic stone/tissue discrimination system offers an alternative to the rhodamine 6G dye laser system at less than half the financial investment. Effective stone fragmentation is accompanied by only low tissue alteration. The holmium:YAG laser is an effective multidisciplinary lithotriptor, but it can be used only under cholangioscopic control, limiting its use to gastroenterologic centers.

Biliary stenting for management of common bile duct stones

Large and multiple common bile duct stones may defy extraction despite an adequate endoscopic papillotomy. We treated 65 patients with symptomatic bile duct stones with endoscopic stents after failed attempts at stone extraction. Of the 65 patients, bile duct stones were extracted in eight at a second attempt, 29 underwent elective surgery and 28 patients were followed with the stent in situ for 21-52 months (median 42 months). During follow up, two patients had recurrent pain and two required surgery. The remaining 24 patients remained asymptomatic. Biliary stenting is a safe and effective mode of treatment for common bile duct stones in patients who have failed stone extraction after endoscopic papillotomy.

Potential health effects of gasoline and its constituents: A review of current literature (1990-1997) on toxicological data

We reviewed toxicological studies, both experimental and epidemiological, that appeared in international literature in the period 1990-1997 and included both leaded and unleaded gasolines as well as their components and additives. The aim of this overview was to select, arrange, and present references of scientific papers published during the period under consideration and to summarize the data in order to give a comprehensive picture of the results of toxicological studies performed in laboratory animals (including carcinogenic, teratogenic, or embryotoxic activity), mutagenicity and genotoxic aspects in mammalian and bacterial systems, and epidemiological results obtained in humans in relation to gasoline exposure. This paper draws attention to the inherent difficulties in assessing with precision any potential adverse effects on health, that is, the risk of possible damage to man and his environment from gasoline. The difficulty of risk assessment still exists despite the fact that the studies examined are definitely more technically valid than those of earlier years. The uncertainty in overall risk determination from gasoline exposure also derives from the conflicting results of different studies, from the lack of a correct scientific approach in some studies, from the variable characteristics of the different gasoline mixtures, and from the difficulties of correctly handling potentially confounding variables related to lifestyle (e.g., cigarette smoking, drug use) or to preexisting pathological conditions. In this respect, this paper highlights the need for accurately assessing the conclusive explanations reported in scientific papers so as to avoid the spread of inaccurate or misleading information on gasoline toxicity in nonscientific papers and in mass-media messages.

Choledocholithiasis and gallstone pancreatitis

Gallstones are commonly found within the main bile duct (MBD) of patients undergoing cholecystectomy. Retained MBD stones are a common cause of obstructive symptoms and complications. Endoscopic retrograde cholangiopancreatography (ERCP) and sphincterotomy (ES) is the recommended modality for both the detection of such stones and their extraction. Recent trials of ERCP in conjunction with laparoscopic cholecystectomy suggest that it should be reserved for use post-operatively. Gallstones within the MBD are the most common single cause of acute pancreatitis. Initial treatment is supportive, although new agents designed to suppress the systemic inflammatory response are under development and have proved beneficial in clinical trials. Severe cases should be treated with systemic antibiotics and early removal of the obstructing stones by ERCP and ES. Prophylactic cholecystectomy is recommended to prevent further attacks of gallstone pancreatitis.

Endoscopic intracorporeal laser lithotripsy of difficult common bile duct stones with a stone-recognition pulsed dye laser system

BACKGROUND

Endoscopic retrograde intracorporeal lithotripsy with a stone recognition laser system seems to be a promising alternative in patients with difficult bile duct stones.

METHOD

Sixteen patients with bile duct stones not suitable for endoscopic standard procedures underwent intracorporeal laser lithotripsy during a 3-month period. An average of 6800 (120 to 25000) discharges were applied with a power setting of 100 mJ. Inserting the laser fiber into a radiopaque marked catheter or into a balloon catheter guaranteed a successful location on the stone surface in 70% of all discharges. The automatic feedback/cut-off at the fiber is not in contact with the stone surface.

RESULTS

Fragmentation was achieved in all cases. Complete bile duct clearance was reached in 14/16 cases. In two cases, remaining fragments passed spontaneously through the papilla as controlled by ERCP. Minor complications were noted in two patients (hemobilia, cholangitis). Complete recovery was achieved in both patients with conservative management.

CONCLUSIONS

For a selected group of patients with difficult common bile duct stones, intracorporeal laser lithotripsy with a stone recognition laser system was found to be a highly effective and safe technique.

Contact solvents for common bile duct stones. Study in an in vitro system

Cholesterol and brown pigment stones found in the common bile duct are often radiolucent and therefore indistinguishable. The purpose of this study was to define contact solvent systems able to dissolve both stone types. The influence of mucolytic agents on in vitro pigment stone dissolution was first determined. It was shown that dithioerythritol induced more rapid dissolution than N-acetylcysteine. Alternating treatment with an aqueous alkaline solvent (pH = 9.5), composed of sodium deoxycholate 50 mM, ethylenediaminetetraacetate 26 mM and dithioerythritol 50 mM, for 45 min, and an organic solvent methyl tert-butyl ether/dimethyl sulfoxide (90/10) for 15 min, was more effective for bilirubin, cholesterol, and fatty acid solubilization (p < 0.01) than using these solvents separately. The dissolution of brown stones was nearly completed within 9 h and that of mixed cholesterol stones was obtained within 3 h. We conclude that the alternating treatment described is very effective for the rapid in vitro dissolution of the two major stone types present in the bile ducts, and deserves further assessment in vivo.

Biliary endoprostheses in elderly patients with endoscopically irretrievable common bile duct stones: report on 117 patients

BACKGROUND

Endoscopic sphincterotomy and stone extraction can clear the bile ducts in 85% to 90% of patients. In case endoscopic stone extraction fails, insertion of a biliary endoprosthesis is an alternative.

METHODS

Biliary endoprostheses were inserted in 117 patients (73 women and 44 men, median age 80 years). Follow-up was achieved by contacting referring physicians and general practitioners.

RESULTS

Biliary drainage was established in all patients. Early complications occurred in 10 patients (9%) with a fatal outcome in 1. In 59 patients the endoprosthesis was a temporary measure before elective surgery or repeat endoscopy. Further treatment in these 59 patients caused only mild complications and there were no deaths. Endoprostheses were inserted as permanent therapy in 58 patients. Median follow-up in these 58 patients was 36 months (range, 1 to 117 months). A total of 34 complications occurred in 23 patients (40%), cholangitis being the most frequent. During follow-up, 44 patients died, 9 as a result of a biliary-related cause.

CONCLUSIONS

These data favor temporary use of biliary endoprostheses in patients with endoscopically irretrievable bile duct stones. However, as a permanent therapy, late complications occur in many patients and the risk increases proportionally in time. Therefore, permanent biliary stenting should preferably be restricted to patients unfit for elective treatment at a later stage and with a short life expectancy.

Treatment options for large common bile duct stones

This is a retrospective analysis of the medical records of patients diagnosed to have large common bile duct stones (> 15 mm). The study was designed to evaluate different modalities of large bile duct stone treatment. The setting is King Khalid University Hospital, Gastroenterology Unit. The medical records of patients (n=64) diagnosed to have large common bile duct stones by endoscopic retrograde cholangiography over a period of nine years were included. Files were reviewed and information obtained which included patients' age, sex, nationality, presenting symptoms, number and size of bile duct stones, presence of ascending cholangitis, mode of treatment received, complications and outcome. There were a total of 64 patients; 28 males and 36 females, with a mean age of 61 + 16.6 years. Successful stone extraction was achieved in 44 (69%) patients while surgical treatment was required in 20 patients. Surgically managed patients had significantly larger stones (P<0.003) and were more frequently jaundiced (P<0.014). There was 7.8% of the total number of patients who developed complications that were managed conservatively with full recovery. It was concluded that large stones are difficult to extract endoscopically and more frequently require additional treatment.

Toxic effects of cholelitholytic solvents on gallbladder and liver. A piglet model study

We evaluated the toxic effects of four currently used chemolytic solvents--dimethyl sulfoxide (DMSO, 99%), ethyl propionate (EP, 99%), tetrasodium ethyl-dimethyl tetraacetate (4Na-EDTA, 2%, pH 11), and methyl tert-butyl ether (MTBE, purity = 99.5%) in an animal model. Each solvent was tested in nine farm piglets (Landrace), weighing between 20 and 25 kg. A solvent-resistant catheter was inserted transhepatically into the gallbladder (GB) using sonographic guidance 24 hr prior to each experiment. Seventy-five milliliters of each solvent was infused over 3 hr into the gallbladder. The following day, a laparotomy was performed in order to assess for possible damage to the liver, GB, bile ducts (BD), or intestines. The GB and liver were resected and their histology examined. The following pathologic grades were assigned to GB, BD, and liver specimens to describe the tissue damage: normal (0), mild (1), moderate (2), and severe (3). We found that DMSO had the highest score on gallbladder and bile duct injury (49, 3), followed by EP (36, 2), EDTA (14, 1) and MTBE (16, 0), respectively; the difference in gallbladder damage was statistically significant. Very mild hepatocyte damage was present in the DMSO (2) and MTBE (2) groups. The administration of EP and EDTA resulted in no liver injury at all. Piglets within each treatment group suffered from varying degrees of tissue injury. No deaths were attributed to the administered solvents. We concluded that DMSO, EP, EDTA, and MTBE do not have serious local toxic effect on the GB, BD, and intestine; nor do they lead to severe hepatotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of bile duct stones in the era of laparoscopic cholecystectomy

The introduction of laparoscopic cholecystectomy has resulted in increased options for the management of bile duct stones and has stimulated a fundamental reappraisal of the situation before the laparoscopic era. This article reviews the natural history of bile duct stones and details the different ways in which they may now be treated. New areas of controversy are highlighted and the need for further studies is emphasized.

Endoscopic retrograde cholangiography and laparoscopic cholecystectomy: stones, stents and sphincterotomy

Endoscopic retrograde cholangiopancreatography (ERCP) is clearly a useful adjunct in the management of patients undergoing laparoscopic cholecystectomy who have common bile duct stones. Whether endoscopic sphincterotomy plus laparoscopic cholecystectomy is superior to traditional open cholecystectomy and bile duct exploration is a question which remains to be answered by prospective, randomized trials. The immense popularity of laparoscopic cholecystectomy may prohibit such a study in the USA. In expert hands, endoscopic stone extraction is usually successful, so ERCP can be deferred until after cholecystectomy unless there is serious suspicion of a duct stone preoperatively. Actual clinical practice will depend, however, on the skill of the surgeon, the skill of the endoscopist, and the commitment to removing the gallbladder laparoscopically. It would seem prudent for surgeons to continue to direct their energy toward conquering the common bile duct via the laparoscope, and leave ERCP and stone extraction in the realm of the endoscopist who has been extensively trained in this difficult technique. Proficiency at ERCP, sphincterotomy and stone extraction requires considerable training, and the procedure should not be attempted by individuals who have performed fewer than 100 ERCPs and 25 individually supervised sphincterotomies, according to the ASGE Standards of Training, 1992. As experience with video endoscopic surgery increases and technology improves, it will become possible to remove most duct stones at the time of cholecystectomy, thus obviating the need for endoscopic sphincterotomy. In addition, ERCP should be regarded as the treatment of choice for postoperative cystic duct stump leaks. Studies have shown that any type of biliary decompression, i.e. sphincterotomy, stents or nasobiliary catheters, will be successful. The authors recommend that, in the absence of duct stones, stenting or nasobiliary catheters be used as they are less invasive. Bile duct leaks may also be managed endoscopically, but success depends on the individual characteristics of the duct injury. The decision to manage late onset strictures endoscopically should be individualized, and consideration of local endoscopic expertise, operative risk, interval between surgery and stricture, and the patient's wishes should be made.

Endoscopic extraction of bile duct stones: management related to stone size

Endoscopic sphincterotomy has become the first line treatment for patients with common bile duct (CBD) stones. This technique may fail, however, due to difficult anatomy, previous surgery, periampullary diverticula or the presence of a large stone. The importance of stone size to the success of endoscopic sphincterotomy has not been fully assessed. A prospective study was carried out over the period January 1987 to December 1989 on 100 patients (45 male, 55 female, median age 69 years, range 19-97) with CBD stones in which a policy of early duct clearance was followed. Endoscopic retrograde cholangiopancreatography (ERCP) was performed and the stone size and number recorded from the cholangiograms and corrected for magnification. Sphincterotomy was performed using a diathermy unit with a cutting current and stones were extracted using a balloon catheter or a Dormia basket. Of the 100 patients with CBD stones receiving ERCP, successful clearance of the biliary tree was possible in seven without endoscopic sphincterotomy and five were felt to be unsuitable for endoscopic sphincterotomy. Of the remaining 88 patients endoscopic sphincterotomy was successful in 75 (85%). Of the 75 patients having endoscopic sphincterotomy stone clearance was successful in 44 (59%). There were no deaths and only four complications, which rapidly resolved on conservative treatment (two acute pancreatitis, two bleeding). The number of CBD stones present was similar in those patients with successful endoscopic sphincterotomy and duct clearance (median 1, range 1-10, n = 44) as in those in whom it failed (median 2, range 1-6, n = 31). In contrast there was a highly significant difference when stone size was analysed (successful clearance median stone size 10 mm, range 3-27 mm; unsuccessful: median 18 mm, range 10-42, p<0.001). Stones less than 10 mm in diameter (n=21) were all removed successfully whereas in patients with stones over 15 mm (n=25) only three were removed endoscopically (12%). All patients with evidence of residual stones had additional treatment. Of these 31 patients, 10 had surgery, 11 had insertion of an endoprosthesis, and 10 had dissolution treatment with methyl-tert-butyl ether through a nasobiliary catheter. This study shows the importance of stone size to the success rate of endoscopic removal of bile duct stones.

Treatment of non-extractable common bile duct stones with combination ursodeoxycholic acid plus endoprostheses

Despite widely available technology for removal of bile duct stones, endoscopists currently encounter approximately 3% of patients with stones that defy extraction. After sphincterotomy and unsuccessful attempts at extraction of "defiant" stones, biliary stents were placed in 22 patients. Ten patients were treated with ursodeoxycholic acid, and 12 patients treated only with stent served as control subjects. Ductal strictures preventing stone extraction were present in eight control patients and in six patients treated with ursodeoxycholic acid. The number of total calculi in the ursodeoxycholic acid group was slightly higher (4.2 per patient) than the number in the control group (3.3 per patient). Stone and bile duct dimensions were similar in each group. Nine of 10 patients in the ursodeoxycholic acid group had complete stone clearance, and 41 of 42 stones were removed during a follow-up period of 9 +/- 2 months; in contrast, no patient in the control group had complete clearance and only 6 of 40 stones were removed after a follow-up period of 31 +/- 6 months. Oral ursodeoxycholic acid facilitates extraction of defiant bile duct stones. This treatment is an effective alternative to high-tech extraction methods for large biliary stones.

Systemic and local toxicity in the rat of methyl tert-butyl ether: a gallstone dissolution agent

Methyl tert-butyl ether (MTBE) is an organic solvent that has been used to dissolve gallstones via a percutaneous transhepatic catheter into the gallbladder. To test whether MTBE might cause serious tissue injury if accidentally infused outside the gallbladder, the effect of MTBE (0.2 ml/kg) injected into the hepatic parenchyma, or administered intravenously or intraperitoneally, was examined in the rat. The toxicity of isopropyl acetate (IPA), an organic solvent with a similar chemical structure, was examined similarly. Intracaval injection of MTBE caused the highest mortality (100%). Mortality was less (59%) after intrahepatic injection and still less (17%) after peripheral vein injection. Most animals died instantaneously from cardiorespiratory arrest. Almost all animals that were injected with MTBE intrahepatically or intravenously showed localized areas of congestion, hemorrhage, and interstitial edema in the lungs. These changes were more severe in rats which survived for 24 hr than in those which died sooner. In those rats receiving intrahepatic injections, most rats which survived for 24 hr had liver necrosis at the site of injection. Intraperitoneal injection of MTBE produced 100% survival with only 1/5 rats showing a mild pulmonary injury at autopsy. IPA had toxic effects similar to those evoked by MTBE. To test whether tumor necrosis factor was involved in organ injury, serum levels were measured; they remained unchanged. These experiments indicate that two organic solvents, MTBE and IPA, are cytotoxic to local tissues and cause severe, and often fatal, lung damage when infused into a central vein. Less toxicity occurred if solvents were given into a peripheral or portal vein or intraperitoneally.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-surgical management of bile duct stones refractory to routine endoscopic measures

Endoscopic sphincterotomy and percutaneous approaches to the biliary tract have revolutionized the treatment of bile duct stones. Both the endoscopic and transhepatic approaches are less invasive than open surgery. This is an advantage for the mostly elderly and frail patients with common bile duct stones. Other patients with intrahepatic stones, e.g. young patients with oriental lithiasis, may also profit from the non-surgical approach. In this latter group it is often difficult for the surgeon to obtain access to the stone-bearing bile ducts. Due to the anatomical situation, size or impaction of stones the non-surgical approach, including mechanical disintegration, may primarily fail. Several techniques such as intracorporeal lithotripsy using electrohydraulic probes or laser light, extracorporeal shockwave lithotripsy or direct contact dissolution are now available and often allow complete clearance of the bile ducts. If a kidney lithotripter with radiographic devices is available, it should be used after an attempt at mechanical lithotripsy has failed (Figure 1). According to the literature, experience with this method is greater than with any other 'third-step approach'. The procedure is simple, relatively safe and successful in approximately 80% of patients. However, in at least one third of patients, several sessions have to be performed and further endoscopy is frequently required for extraction of fragments. Intracorporeal techniques may become the procedure of choice in the future, at least in patients with common bile duct stones. At the moment, however, the different devices are still not fully developed and too susceptible to damage. A further major drawback, especially with high-energy electrohydraulic intracorporeal lithotripsy, is the danger of bile duct injury or even perforation, so that most procedures must be performed under optical control. The use of contact dissolution cannot generally be recommended. Treatment with mono-octanoin or modified mono-octanoin solvents takes too long, is often not successful and has a high rate of side-effects. MTBE may shorten the procedure considerably, but is suitable only for cholesterol stones, and the danger of spill-over into the intestine with absorption and systemic side-effects has to be weighed against the probability of success.

Acute effects of topical methyl tert-butyl ether or ethyl propionate on gallbladder histology in animals: a comparison of two solvents for contact dissolution of cholesterol gallstones

Experiments were performed in anesthetized rabbits and piglets to assess gallbladder mucosal injury during irrigation with methyl tert-butyl ether, a C5 ether, or ethyl propionate, a C5 ester--two organic solvents used in the contact dissolution of cholesterol gallstones. In 44 New Zealand White rabbits, the gallbladder was exposed to individual solvents or saline solution through a transhepatic catheter for 2 hr. Gallbladders were then harvested and fixed immediately or after a recovery period of 1, 4 or 8 days. Tissue sections were examined under light microscopy, and severity of injury was graded with predefined criteria by two pathologists blinded to the animals' treatment regimens. Histological assessment showed severe mucosal injury such as necrosis of the cells at the villus tips immediately after 2 hr of exposure to either solvent. After 4 days, injury had decreased significantly; after 8 days, complete mucosal healing had taken place. A similar study was performed in 32 piglets. Solvent or saline solution was oscillated in and out of the gallbladders of these piglets with a computer-controlled syringe pump at a pressure less than the leakage pressure of the gallbladder. Histological assessment was performed on tissue samples obtained immediately after the procedure or 8 days later. Both solvents caused severe mucosal injury; however, after 8 days complete mucosal healing had occurred, so that gallbladders exposed to solvent were indistinguishable from gallbladders exposed to saline solution, which was used as control. We conclude that both methyl tert-butyl ether and ethyl propionate cause moderate to severe epithelial injury but that the gallbladder epithelium regenerates within a few days.(ABSTRACT TRUNCATED AT 250 WORDS)

Endoscopic management of bile duct stones

The surgical risk of common duct exploration for the treatment of biliary calculi is considerably higher than that of cholecystectomy. Therefore, introduction of endoscopic sphincterotomy in 1974 was a major advance. It has become the therapy of choice in cholecystectomized patients or in those with an increased operative risk. Endoscopic sphincterotomy has a mortality rate of around 1% and a morbidity rate of 7%. These figures compare favourably with open surgery, especially in old patients. The procedure fails in about 10% of all patients referred for endoscopic removal of their calculi. However, several techniques have been described or are currently under evaluation to overcome these failures: intracorporeal or extracorporeal lithotripsy, long-term stenting of the bile duct, or direct application of solvents. Long-term follow-up studies show that between 2% and 20% of successfully managed patients may develop recurrent stones, mainly caused by bile stasis and infection. Patients with a functioning gall-bladder and no concomitant gall-bladder stones probably do not require cholecystectomy after successful endoscopic treatment of their choledochal stones. While endoscopic stone removal has replaced surgery in the elderly frail patients it has no major advantages in the young and fit patients, especially when the gall-bladder is still in situ.

Choledocholithiasis treated by ethylenediaminetetraacetic acid infusion through an endoscopic nasobiliary catheter

A 64 year old man was admitted to the National Cheng Kung University Hospital for obstructive jaundice. He had received cholecystectomy 5 years previously. Sonography revealed common bile duct stones. He was treated with endoscopic nasobiliary drainage (ENBD) for 5 days for concomitant cholangitis. The muddy pigment stones disappeared completely after 10 days of infusion of ethylenediaminetetraacetic acid (EDTA) via the ENBD tube. There were no adverse effects, and he was stone-free 4 months later.

Percutaneous flexible choledochoscopy: a simple method for retained common bile duct stone removal

Conventional methods of treatment of retained common bile duct stones found on T tube cholangiography after common bile duct exploration include percutaneous extraction under fluoroscopic control and endoscopic sphincterotomy. Four cases of percutaneous stone extraction under direct vision using the flexible choledochoscope are described. Clearance of the bile ducts was achieved at one sitting in three cases and four sittings in one case. Follow-up tube cholangiography was performed in two cases and confirmed complete clearance. Percutaneous endoscopic stone extraction can be performed by any surgeon with experience of flexible choledochoscopy and offers the advantages of a minimally invasive procedure without the use of specialized equipment.

Percutaneous dissolution of gallstones

Contact dissolution with MTBE is an effective and safe method to treat symptomatic patients with cholesterol gallstones. Personnel, time, and safety factors have limited widespread use of the procedure. With current competing methods to treat gallstones, it is likely that MTBE use will be reserved for those patients who elect percutaneous therapy due to fear of surgery or anesthesia and in those elderly patients who are compromised by underlying medical conditions.