|Year : 2014 | Volume
| Issue : 1 | Page : 12-17
Role of hepatobiliary tract anatomy and morphology of gallstones in causation of acute pancreatitis
Bhavesh Devkaran1, Arun Chauhan1, Ashish Chaba1, Satinder Minhas1, Charu Smita Thakur2, Shruti Thakur2, Archana Dogra3
1 Department of General Surgery, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India
2 Department of Radiodiagnosis, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India
3 Department of Physiology, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India
|Date of Web Publication||21-May-2014|
Department of General Surgery, Indira Gandhi Medical College, Shimla, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Gall stone disease is a common cause of acute pancreatitis. At present the pattern of gall stones complication are largely unpredictable. Little research has been done to identify gall stone morphology and biliary tract anatomy in the causation of gall stone induced pancreatitis. Aims and Objectives: The present study was done at IGMC Shimla to study the relationship of gallstone characteristics to the risk of gall stone pancreatitis and to compare and evaluate the biliary tract anatomy in patients of gall stone induced pancreatitis and cholelithiasis by MRCP. Materials and Methods: The prospective study included 25 patients each of symptomatic cholelithiasis and gall stone induced pancreatitis divided into Group A and Group B respectively. All the patients were subjected to MRCP preoperatively. All the patients were operated by laproscopic or open method. Postoperatively the gall stone were collected and analyzed. Results: On MRCP- In Group A Single calculus was present in 11 (44%) patients and 1 (4%) patients had associated sludge, 14 (56%) patients had multiple calculi and 3 (44%) patients had associated sludge.In Group B 22 (88%) patients had multiple calculi and 16 (56%) patients had associated sludge, 3 (12%) patients had single stone, and 2 (8%) patients had associated sludge. In Group A, CBD stones were seen in 3 (12%) patients, cystic duct diameter ranged from 3 mm to 5.2 mm, CBD diameter ranged from 5 mm to 9 mm and pancreatic duct diameter ranged from 2.7 mm to 4 mm.In Group B, CBD stones were seen in 7 (28%) patients, cystic duct diameter ranged from 4 mm to 6.4 mm, CBD diameter ranged from 5 mm to 12 mm and pancreatic duct diameter ranged from 2.6 mm to 4.8 mm In Group A, Common channel was seen in 8 (32%) patients. In Group B, Common channel was seen in 18 (72%) patients Gall Stone Morphology- In Group A, Single calculus present in 11 (44%) patients and 1 (4%) patient had associated sludge. Multiple calculi present in 14 (56%) patients and 3 (12%) patients had associated sludge. In Group B, Single calculus present in 3 (12%) patients and 2 (8%) patients had associated sludge. In group A, 15 (60%) patients had round stones and 14 (56%) patients had multifaceted stones and 6 (24%) patients had associated sludge. In Group B, 5 (20%) patients had round stones and 14 (56%) patients has multifaceted stones and 6 (24%) patients had associated sludge. Sludge <2 mm diameter was present in 6 patients each in Group A and B. Weight ranged from 2 to 3.8 gm in Group A and in Group B from 1.6 to 3.25gm. Conclusion: The present study clearly established an association between multiple, multifaceted stones, sludge, wide cystic duct and presence of common channel with increased incidence of Gallstone induced pancreatitis, MRCP also proved to be an excellent diagnostic modality in Gall stone induced pancreatitis.
Keywords: Acute pancreatitis, gall stones, magnetic resonance cholangiopancreatography, morphology
|How to cite this article:|
Devkaran B, Chauhan A, Chaba A, Minhas S, Thakur CS, Thakur S, Dogra A. Role of hepatobiliary tract anatomy and morphology of gallstones in causation of acute pancreatitis. Saudi Surg J 2014;2:12-7
|How to cite this URL:|
Devkaran B, Chauhan A, Chaba A, Minhas S, Thakur CS, Thakur S, Dogra A. Role of hepatobiliary tract anatomy and morphology of gallstones in causation of acute pancreatitis. Saudi Surg J [serial online] 2014 [cited 2020 Jul 10];2:12-7. Available from: http://www.saudisurgj.org/text.asp?2014/2/1/12/132896
| Introduction|| |
Acute pancreatitis is a common disease with considerable morbidity and mortality. Common causes of acute pancreatitis include gallstones (40-65%) and alcohol (25-40%).  The mechanism by which gallstones might trigger acute pancreatitis remains a subject of debate. The common channel theory suggests that an impacted stone in the distal bile duct might create behind it a common channel allowing the reflux of bile into the pancreatic duct triggering acute pancreatitis.  In many patients, however the union of main bile duct and main pancreatic duct is too short to allow the formation of such common channel. Another theory known as the duodenal reflux theory suggests that stones may pass through the Sphincter of Oddi More Details and stretch the muscles making it incompetent, as a result duodenal juices containing activated pancreatic digestive enzymes could reflux through the incompetent sphincter into the pancreatic duct causing acute pancreatitis. 
The most widely accepted theory is based on the concept of the pancreatic duct obstruction. This theory suggests that the impaction of triggering gallstones or alternatively the edema and inflammation resulting from the passage of such gallstones could obstruct the pancreatic duct. Continuing secretion into the obstructed duct causes ductal hypertension resulting in the extravasation of pancreatic juice in the pancreatic parenchyma triggering pancreatic injury.  Pathophysiology of acute pancreatitis includes activation and release of pancreatic enzymes in the interstitium, the autodigestion of pancreas and multiple organ dysfunction after their release in the systemic circulation.
Little research has been done to identify the patient anatomical characteristics associated with complicated course of the disease. If such factors are known then the patients who fall into the higher risk group can be identified and appropriate early surgical treatment can be provided to prevent morbidity and mortality due to acute pancreatitis. It was the intention of the present study to evaluate the association of gallstone morphology and hepatobiliary anatomy with the occurrence of acute gallstone induced pancreatitis.
| Materials and Methods|| |
The study was conducted in the Department of Surgery and Department of Radiodiagnosis, IGMC, Shimla over 1-year period between May 1, 2008 and April 30, 2009. The study involved 50 patients who were included after taking informed consent. The study was approved by the hospital ethical committee. The 25 patients with uncomplicated biliary pain and proven gallstones were included in one group (Group A), whereas the 25 patients with gallstone induced pancreatitis were included in the other group (Group B). Patients with other causes of pancreatitis were excluded from the study. Apart from thorough history and clinical examination, patients of both the groups underwent blood investigations as well as radiological imaging. Gallstones were confirmed in both the groups with ultrasound abdomen imaging and subsequently patients of both groups were imaged by magnetic resonance imaging (MRI) abdomen with magnetic resonance cholangiopancreatography (MRCP).
Technique used in magnetic resonance imaging and magnetic resonance cholangiopancreatography
Magnetic resonance imaging abdomen was performed along with MRCP using the following protocol. Patients were kept fasting 6 h prior to the procedure. Imaging was done in the supine position with body coils. Gadolinium based contrast agent was used (volume 10 ml, flow rate 2-3 ml/s followed by 20 ml saline injected at the rate of 2-3 ml/s. 4 measurements were taken with a dynamic contrast with a scan delay of 10, 35, 60, 300 s. Section thickness was 5 mm. The patients with gallstone induced acute pancreatitis were taken up for surgery soon after recovery from the attack, while Group A patient underwent elective surgery. The physical characteristics of the recovered gallstones were observed and noted preoperatively.
| Results|| |
The age ranged between 32 and 65 years in Group A with mean age being 44.9 ± 8.54 years. The age ranged between 25 and 64 years in Group B with a mean of 46.7 ± 8.09 years.
In Group A, 17 (58%) patients were female, while 8 (32%) were males. In Group B, 13 (52%) patients were male and 12 (48%) were female. General physical examination revealed obesity in 12 (48%) patients in Group A and 14 (56%) patients in Group B.
Systemic examination was normal in Group A patients. Voluntary guarding with tenderness was evident in18 (72%) patients of Group B. Bilateral pleural effusion was present in 1 (4%) patient while exclusive left side pleural effusion was seen in 2 (8%) patients in Group B. Periumbilical discoloration of skin (Cullen sign) was evident in 1 (4%) patient of Group B.
The average gallbladder wall thickness in Group A was 2-4 mm. Single calculus was evident in 11 (44%) patients in Group A, while single calculus was present in 3 (12%) patients in Group B. Multiple calculi were present in 14 (56%) patients in Group A and 22 (88%) patients in Group B. Pericholecystic fluid was present in 11 (44%) patients in Group B.
Common bile duct (CBD) size in Group A varied between 5 and 9 mm. Mean size of CBD in Group A 6.04 + 1.17 mm. CBD size ranged from 6 to 12 mm with a mean diameter 6.84 + 1.77 mm in Group B patients. Ultrasonography revealed dilated CBD up to midportion in 2 (8%) patients and a dilated CBD until lower end in 1 (4%) patient in Group A. CBD was dilated until mid-portion in 3 (12%) patients and up to the lower end in 4 (16%) patients in Group B. Calculus was visualized in mid CBD in 1 (4%) patient in group a while calculus was visualized in mid CBD in 2 (8%) patients and in the lower end in 1 (4%) patient in Group B.
Magnetic resonance cholangiopancreatography findings
The diameter of the cystic duct in Group A ranged from 3 to 5.2 mm with a mean of 4.26 ± 0.48 mm. The diameter of the cystic duct in Group B ranged from 4 to 6.4 mm with a mean of 5.44 ± 0.6 mm.
The diameter of CBD in group a ranged from 5 to 9 mm. The mean diameter of CBD in Group A was 6.04 ± 1.17 mm. In Group B, the diameter of CBD ranged from 5 mm to 12 mm with a mean diameter of CBD being 6.84 ± 1.77 mm.
The diameter of pancreatic duct in Group A ranged from 2.7 to 4 mm. The mean diameter of the pancreatic duct being 3.52 ± 0.43 mm.
The diameter of pancreatic duct in Group B ranged from 2.6 to 4.8 mm. The mean diameter being 3.62 ± 0.49 mm [Table 1].
Eight (16%) patients in Group A had a common channel detectable on MRCP, while 18 (72%) patients in Group B had common channels [Table 1], [Figure 1].
The patients of gallstone induced pancreatitis underwent interval cholecystectomy 3-10 weeks after the attack of gallstone induced pancreatitis with a mean of 6 ± 1.52 weeks.
A single calculus was found in 11 (44%) patients in Group A, while multiple calculi were present in 14 (56%) patients in Group A.
Of 14 patients with multiple calculi, sludge (stone size <2 mm) was present in 3 (12%) patients in Group A.
Single calculus was present in 3 (12%) patients in Group B. Of these 2 (8%) had single calculus associated with sludge. Multiple calculi were found in 22 (88%) patients. Sludge was found in 6 (24%) patients out of 22 (88%) patients with multiple calculi.
Oval to round shaped calculi were found in 15 (60%) patients in Group A while multifaceted calculi were found in 7 (28%) patients in Group A [Figure 2] and [Figure 3].
Smooth stones were found in 5 (20%) patients in Group B. Multifaceted stones were detected in 14 (56%) and sludge was found in 6 (24%) patients in Group B.
In Group A size calculus ranged from 2 to 18 mm. Although in Group B range was between 2 mm and 1 cm.
Weight of stone-the weight of stones in group a ranged from 2 to 3.8 g with mean being 3.07 ± 0.58 g. In Group B, the weight ranged from 1.6 to 3.25 g. The mean weight being 2.30 ± 0.49 g.
| Discussion|| |
Female gender has been reported to have a higher incidence of gallstones as compared to males and the same was evident in Group A where female to male ratio was observed to be 2.12.
In Group B, the female to male ratio was 0.92. In addition to increased incidence of gallstone induced pancreatitis in male gender, men suffered from gallstone induced acute pancreatitis at an early age compared with their female counterparts (P = 0.024). This result was comparable to other studies, which revealed higher incidence of AP in men compared to females. 
Pain was the predominant presentation of patients in both the groups although 7 (28%) patients of Group B in addition to pain also had jaundice. 24 (96%) patients complained of pain abdomen in Group A while jaundice was present in 3 (12%) patients.
Two (8%) patients had to be readmitted prior to surgery on account of relapse of pain abdomen following initial recovery in Group B. Both the patients were managed conservatively for recurrent pancreatitis and were operated at the earliest and recovered satisfactory.
Total leucocyte count was raised in 22 (88%) patients in Group B, while it was normal in Group A.
The serum amylase levels were normal in all patients of Group A, while it ranged between 128 and 1498 IU in Group B. Of a total of 25 patients, 22 (88%) patients had serum amylase levels >3 times of their base value limit. Amylase levels are not considered specific for diagnosis of acute pancreatitis.  Up to 19% of all patients with pancreatitis have normal serum amylase levels and other investigations are required to effectively establish the diagnosis of acute pancreatitis.
Three patients with acute pancreatitis had pleural effusion on X-rays. In acute pancreatitis X-rays have low sensitivity values. A left sided pleural effusion and gas distended duodenum on proximal bowel loop are helpful findings, but are present in a minority of patients. A gas distended transverse colon is seldom seen in acute pancreatitis and is of low specificity. 
It is universally accepted that ultrasonography is a useful modality for evaluating the biliary tract for gallstones and biliary obstruction as well as for follow-up of pancreatitis patients for fluid collections. 
The efficacy of ultrasound in detecting CBD stones is rather low with sensitivity, specificity, positive predictive value and negative predictive value reported to be 36%, 90%, 78%, and 50% respectively.  In this study, the sensitivity was 33.3% and specificity was 75%, while positive predictive value was 42.88% and negative predictive value was 66.66%. The low detection of CBD stones on ultrasonography may be attributed to obscuring of the CBD by overlying gut gases. Second the ductal system may not be so dilated in choledocholithiasis to be obvious on ultrasonography due to intermittent obstruction.
Multiple calculi were present in the majority of patients (88%) with gallstone induced pancreatitis as compared to patients with just gallstones (56%).
The mean diameter of the cystic duct in Group A was 4.26 ± 0.48 mm. In Group B, the mean cystic duct diameter was 5.44 ± 0.60 mm suggesting a wider cystic duct in patients with gallstone induced pancreatitis. The difference in diameter in the two groups was found to be statistically significant (P < 0.05). This is in accordance with the studies, which report a higher incidence of gallstone induced pancreatitis in patients with wider cystic duct. 
The diameter of CBD reported on MRI was between 5 and 12 mm with a mean of 6.84 ± 1.77 mm in Group B patients, while the mean diameter in Group A was 6.04 ± 1.17 mm. The difference was not found to be statistically different in the two groups.
Although studies have reported dilated CBD in patients with pancreatitis with sizes, which are significantly higher than simple gallstone disease patients however no such relationship could be established on the basis of the present study, which may be accounted to the fact that the present study was a small sample study.
The mean pancreatic duct diameter in Group A was 3.62 ± 0.49 mm. It was 3.52 ± 0.43 mm in Group B. The difference in sizes of the pancreatic duct was not found to be statistically significant. These findings were in accordance with other studies, which showed no significant difference in pancreatic duct diameter in patients with or without gallstone induced pancreatitis. 
Magnetic resonance cholangiopancreatography revealed presence of common channel in 8 (32%) of the patients with symptomatic cholelithiasis. In patients with gallstone induced pancreatitis the common channel was present in 18 (72%) patients. The association of acute pancreatitis in patients with common channel in Group B was found to be statistically significant compared to Group A (P < 0.0005). In other studies, the presence of common channel in patients with gallstone induced pancreatitis has been reported to extent of 67% compared with 32% in patients with cholelithiasis.  Thus common channel appears to be an important factor in the etiology of gallstone induced pancreatitis. Its presence in addition to gallstones signifies a need for early treatment of the pathology even in the absence of symptoms. However, it must be noted that performing a MRI study to visualize common channel as a routine in all patients of symptomatic gallstone disease is neither feasible nor recommended as ultrasonography serves to effectively diagnose gallstones in a majority. Therefore, MRI should be considered in high risk cases or where the clinician deems necessary.
Preoperatively, a single calculus was found in 11 (44%) patients in Group A. A single patient among these had associated sludge present in the gallbladder.
Round to oval calculi were found in 15 patients in Group A, while multifaceted calculi were present in 7 (28%) patients in Group A. In Group B, the smooth round calculi were found in 5 (20%) patients, while multifaceted calculi were found in 14 (56%) patients. 6 (24%) patients had sludge along with multiple calculi. The association of multifaceted calculi with the association of gallstone induced pancreatitis was found to be statistically significant (P < 0.00028). This is in accordance with other studies, which state that numerous small stones having irregular shape tend to be more commonly associated with gallstone induced pancreatitis. Diehl et al. in a study showed if stone size is <5 mm the risk of gallstone induced pancreatitis increases four folds.  They also showed that 50% of patients with acute pancreatitis had 20 or more stones and only few patients had solitary stones. A study by Kim et al. concluded that stones size <5 mm in diameter and stone number >20 have more than three folds increases risk of presenting with acute pancreatitis.  McMahon and Shefta concluded that small faceted sharp irregular stones were significantly more common in patients with acute pancreatitis than in controls. 
The mean weight of stones in Group A and Group B was 3.07 ± 0.58 g 2.3 ± 0.49 g respectively. The difference in weight in Group A and Group B was found to be statistically significant (P < 0.05). These findings are similar to a study done by Diehl et al. in which patients with acute pancreatitis had median total weight lower than in those with uncomplicated pain (2 g vs. 3.05 g). 
| Conclusion|| |
Though our understanding of the etiopathogenesis, diagnosis and treatment of gallstone induced acute pancreatitis has increased considerably over last few decades, this disease still has significantly higher morbidity and associated mortality that requires curtailment. The aim of this study was to link the morphology of gallstones and hepatobiliary anatomy as an etiological factor in the causation of gallstone induced acute pancreatitis. The present study pointed toward an association between the occurrence of multiple, multifaceted stones in patients and acute pancreatitis. This study also reconfirmed the earlier reported association between wide cystic duct and increased prevalence of common channel with gallstone induced acute pancreatitis. MRCP in the present study proved to be an excellent diagnostic modality in Acute Pancreatitis over conventional radiological imaging techniques. MRCP can be included in the current MRI protocol as a primary investigation tool for patients with suspected acute pancreatitis. It offers a noninvasive, reproducible alternative without the limitations and disadvantages of endoscopic retrograde cholangiopancreatography. MRCP should form a prime investigation in the diagnosis of acute pancreatitis in years to come and also in evaluating the biliary system and gallstones in high risk cases. The patients with multiple small faceted gallstones and sludge, with wide cystic duct and common channel may be the candidates to develop gallstone induced acute pancreatitis and thus require appropriate management at the earliest.
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[Figure 1], [Figure 2], [Figure 3]