Updated: Aug 27, 2009
The term postcholecystectomy syndrome (PCS) describes the presence of symptoms after cholecystectomy.1 These symptoms can represent either the continuation of symptoms thought to be caused by the gallbladder or the development of new symptoms normally attributed to the gallbladder. PCS also includes the development of symptoms caused by removal of the gallbladder.
In general, PCS is a preliminary diagnosis and should be renamed relevant to the disease identified by an adequate workup. PCS is caused by alterations in bile flow due to the loss of the reservoir function of the gallbladder. Two types of problems may arise. The first problem is continuously increased bile flow into the upper GI tract, which may contribute to esophagitis and gastritis. The second consequence is related to the lower GI tract, where diarrhea and colicky lower abdominal pain may result.2 This article mainly addresses the general issues of PCS.
PCS reportedly affects about 10-15% of patients. In this author's experience, PCS has occurred in 14% of patients. Effective communication between patients and their physicians, with specific inquiry directed at eliciting frequently anticipated postoperative problems, may be necessary to reveal the somewhat subtle symptoms of PCS.
In 1947, Womack and Crider first described PCS, defining it as the presence of symptoms after cholecystectomy.3 These symptoms may actually represent either (1) the continuation of symptoms that had been interpreted as resulting from pathology of the gallbladder or (2) the development of new symptoms that might normally be attributed to the gallbladder. PCS is also the development of symptoms, such as gastritis and diarrhea, caused by removal of the gallbladder.
In the 1860s, cholecystotomy was the common surgical means of treating a diseased gallbladder. Cholecystectomy became routine about 20 years later. Cholecystectomy proved successful in treating the symptoms of biliary colic and cholecystitis in 80-95% of patients with stones. When stones were not present, the failure rate was as high as 40%.
In the 1920s, oral cholecystography (OCG), an important preoperative aid in the detection of stones or nonfunctioning gallbladders, was developed.
Since then, a wide variety of noninvasive imaging techniques have proven useful in the preoperative assessment of the gallbladder. Ultrasonography is the most accessible and cost-effective approach in most institutions.
Other noninvasive techniques include hepatobiliary scintigraphy with technetium-99m (99m Tc) – labeled iminodiacetic acid, otherwise known as a hepatoiminodiacetic acid (HIDA) scan with and without calculation of cholecystokinin (CCK)-stimulated ejection fraction (EF). Computed tomography (CT) scanning, helical or spiral CT scanning, and magnetic resonance cholangiopancreatography (MRCP) may be useful.
More invasive procedures that may prove valuable in defining the biliary anatomy include percutaneous transhepatic cholangiography (PTC) and endoscopic retrograde cholangiopancreatography (ERCP), with and without biliary and ampullary manometry and sphincterotomy. The intraoperative cholangiogram (IOC), along with a variety of different instrumentation methods, has been in use since the 1930s and has helped in the evaluation of the bile ducts at the time of surgery. These procedures have helped reduce the incidence of PCS because of better preoperative evaluation and diagnosis, especially in patients without stones.
Approximately 500,000-600,000 cholecystectomies were performed each year in the United States during the late 1990s, most of which were laparoscopic. With at least 10% of patients developing PCS, approximately 50,000 cases or more of PCS occur each year. Articles on PCS from the 1920s-1940s primarily focused on anatomical abnormalities that were grossly or microscopically identifiable at the time of exploratory surgery. With improvements in technology and imagining studies, our understanding of biliary tract disorders has improved. This has affected the preoperative workup of patients with suspected gallbladder disease as well as those with PCS, making functional disorders of the biliary tract, including irritable sphincter, the most common causes of PCS.
PCS is usually a temporary diagnosis. An organic or functional diagnosis is established in most patients after a complete workup. Many articles state that a complete preoperative evaluation is essential to minimizing this disease and that patients should be warned of the possibility of postoperative symptoms, which may start at any time from the immediate postoperative period to decades later. Many studies have also been performed in an attempt to identify those at increased risk for PCS and to develop a method of risk stratification. A large portion of data is inconsistent from study to study; however, the consensus opinion holds that the more secure the preoperative diagnosis, the lower the risk of PCS. Other reports find a cause for PCS in as many as 95% of patients.
Bile is thought to be the cause of PCS in patients with mild gastroduodenal symptoms or diarrhea.10 Removal of the reservoir function of the gallbladder alters bile flow and the enterohepatic circulation of bile.
Abu Farsakh et al found gastritis to be more frequent postoperatively (30% vs 50%).11 Preoperatively, no cases of peptic ulcer disease (PUD) occurred, but 3 cases developed postoperatively. It was also shown that fasting gastric bile acid concentration increased after cholecystectomy, and the increase was greater in patients with PCS.
At exploratory surgery, 8% of patients remain without a diagnosis.
Etiologies of Postcholecystectomy Syndrome by Anatomical Location
| Anatomy | Etiology |
| Gallbladder remnant and cystic duct | Residual or reformed gallbladder Stump cholelithiasis Neuroma |
| Liver | Fatty infiltration of liver Hepatitis Hydrohepatosis Cirrhosis Chronic idiopathic jaundice Gilbert disease Dubin-Johnson syndrome Hepatolithiasis Sclerosing cholangitis Cyst |
| Biliary tract | Cholangitis Adhesions Strictures Trauma Cyst Malignancy and cholangiocarcinoma Obstruction Choledocholithiasis Dilation without obstruction Hypertension or nonspecific dilation Dyskinesia Fistula |
| Periampullary | Sphincter of Oddi dyskinesia, spasm, or hypertrophy Sphincter of Oddi stricture Papilloma Cancer |
| Pancreas | Pancreatitis Pancreatic stone Pancreatic cancer |
| Esophagus | Aerophagia Diaphragmatic hernia Hiatal hernia Achalasia |
| Stomach | Bile gastritis PUD Gastric cancer |
| Duodenum | Adhesions Duodenal diverticula Irritable bowel disease |
| Small bowel | Adhesions Incisional hernia Irritable bowel disease |
| Colon | Constipation Diarrhea Incisional hernia Irritable bowel disease |
| Vascular | Intestinal angina Coronary angina |
| Nerve | Neuroma Intercostal neuralgia Spinal nerve lesions Sympathetic imbalance Neurosis Psychic tension or anxiety |
| Bone | Arthritis |
| Other | Adrenal cancer Thyrotoxicosis 20% organ other than hepatobiliary or pancreatic Foreign bodies, including gallstones and surgical clips |
The pathophysiology of PCS is related to alterations in bile flow and remains poorly understood.
Outcome and prognosis vary in accordance with the variety of patients and conditions encountered and the operations that may be performed.
As technology and understanding of the functional disorders of the GI and biliary tracts improve, the ability to make a diagnosis and to treat discovered illnesses will improve. PCS will be a less frequent diagnosis as patients are more efficiently screened and evaluated and as specific diagnoses are confirmed.
[Best Evidence] Mahid SS, Jafri NS, Brangers BC, et al. Meta-analysis of cholecystectomy in symptomatic patients with positive hepatobiliary iminodiacetic acid scan results without gallstones. Arch Surg. Feb 2009;144(2):180-7. [Medline].
Walters JR, Tasleem AM, Omer OS, et al. A new mechanism for bile acid diarrhea: defective feedback inhibition of bile acid biosynthesis. Clin Gastroenterol Hepatol. May 6 2009;[Medline].
Womack NA, Crider RL. The persistence of symptoms following cholecystectomy. Ann Surg. Jul 1947;126(1):31-55. [Medline].
McHardy C. Postcholecystectomy syndrome. Disease-A-Month. 1959;1:1-40.
Peterli R, Merki L, Schuppisser JP, Ackermann C, Herzog U, Tondelli P. [Postcholecystectomy complaints one year after laparoscopic cholecystectomy. Results of a prospective study of 253 patients]. Chirurg. Jan 1998;69(1):55-60. [Medline].
Schoenemann J, Zeidler J. [Sequelae of cholecystectomy]. Z Gastroenterol. Feb 1997;35(2):139-45. [Medline].
Russello D, Di Stefano A, Scala R, Favetta A, Emmi S, Guastella T, et al. Does cholecystectomy always resolve biliary disease?. Minerva Chir. Dec 1997;52(12):1435-9. [Medline].
Anand AC, Sharma R, Kapur BM, Tandon RK. Analysis of symptomatic patients after cholecystectomy: is the term post-cholecystectomy syndrome an anachronism?. Trop Gastroenterol. Apr-Jun 1995;16(2):126-31. [Medline].
Freud M, Djaldetti M, deVries A, Leffkowitz M. Postcholecystectomy syndrome: a survey of 114 patients after biliary tract surgery. Gastroenterologia. 1960;93:288-93. [Medline].
Zollinger R. Observations following distention of the gallbladder and common duct in man. Proc Soc Exper Biol & Med. 1922-23;30:1260-1.
Abu Farsakh NA, Stietieh M, Abu Farsakh FA. The postcholecystectomy syndrome. A role for duodenogastric reflux. J Clin Gastroenterol. Apr 1996;22(3):197-201. [Medline].
Filip M, Saftoiu A, Popescu C, et al. Postcholecystectomy syndrome - an algorithmic approach. J Gastrointestin Liver Dis. Mar 2009;18(1):67-71. [Medline]. [Full Text].
Moody FG, Vecchio R, Calabuig R, Runkel N. Transduodenal sphincteroplasty with transampullary septectomy for stenosing papillitis. Am J Surg. Feb 1991;161(2):213-8. [Medline].
Bartlett MK, Quinby WC Jr. Surgery of the biliary tract. III. Secondary operations of the common bile duct. NEJM. 1957;256:11.
Bensen KW. Dialation of bile ducts and its relation to distress after cholecystectomy. Am J Digest. 1940;7:1-2.
Berk JE. General considerations of gall bladder and biliary tract disorders. Disturbances in Gastrointestinal Motility. 1959;123.
Berk JE, Lee RN. Intravenous cholangiography in detection of stone bearing cystic-duct remnants (so-called re-formed gallbladders). Am J Digest Dis. 1958;3:220.
Beye HL. Conditions necessitating surgery after cholecystectomy. S G & O. 1936;62:191-202.
Boren JA, Walter W. Strictures of the bile ducts and their treatment. Proc Staff Meet Mayo Clin. Jun 15 1955;30(12):245-52. [Medline].
Butsch WL, McGowan JM, Walters W. Clinical studies on the influence of certain drugs in relation to biliary pain and to the variations in intrabiliary pressure. S G & O. 1936;63:451-6.
Cattel RB, Braasch JW. Strictures of the bile duct. S Clin NA. 1958;38:645.
Cattel RB, Colcock BP, Pollack JL. Stenosis of the sphincter of oddi. NEJM. 1957;256:429.
Chernov VN, Khimichev VG, Temchurin ShA. [The postcholecystectomy syndrome and its prevention]. Khirurgiia (Mosk). 1996;(6):57-60. [Medline].
Coakley FV, Schwartz LH, Blumgart LH, Fong Y, Jarnagin WR, Panicek DM. Complex postcholecystectomy biliary disorders: preliminary experience with evaluation by means of breath-hold MR cholangiography. Radiology. Oct 1998;209(1):141-6. [Medline].
Davis L, Hart JT, Crain RC. The pathway for visceral impulses within the spinal cord. S G & O. 1929;48:647-51.
Debray C, Roux M, LeCanuet R. Late results of 300 cholecystectomies performed with the aid of preoperative radiomanometery. Semaine Hop Paris. 1960;36:296.
Dimonte M, Calabrese R. [Post-cholecystectomy syndrome: hepatobiliary scintigraphy and cholangiopancreatography with magnetic resonance in 5 consecutive patients. Comparison of results and integrated diagnosis]. Radiol Med (Torino). Dec 1998;96(6):588-91. [Medline].
Donaldson GA, Allen AW, Bartlett MK. Postoperative bile-duct strictures: their etiology and treatment. NEJM. 1956;254:50.
Doubilet H, Colp R. Resistance of the sphincter in the human. S G & O. 1937;64:622-3.
Doubilet H, Mulholland JH. Eight years of pancreatitis and sphincterotomy. JAMA. 1956;160:521.
Doubilet H, Mulholland JH. Recurrent acute pancreatitis: observations on etiology and surgical treatment. Ann Surg. 1948;128:609.
Dreiling DA. Studies in pancreatic function III. The use of secretin test in the diagnosis of patients with the postcholecystectomy syndrome. Gastroenterology. 1960;16:162.
Dreiling, DA. The functional aspect of biliary colic persistent after cholecystectomy. The postcholecystectomy syndrome. 1962;7:603-12.
Dubin IN. Chronic idiopathic jaundice. Am J Med. 1958;24:268.
Elman R. Common problems in surgical diagnosis. S Clin NA. 1940;20:1247-60.
Elman R. Surgical aspects of acute pancreatitis with special reference to it frequency as revealed by serum amylase. JAMA. 1942;118:1265.
Evans PR, Bak YT, Shuter B, Hoschl R, Kellow JE. Gastroparesis and small bowel dysmotility in irritable bowel syndrome. Dig Dis Sci. Oct 1997;42(10):2087-93. [Medline].
Evans PR, Dowsett JF, Bak YT, Chan YK, Kellow JE. Abnormal sphincter of Oddi response to cholecystokinin in postcholecystectomy syndrome patients with irritable bowel syndrome. The irritable sphincter. Dig Dis Sci. May 1995;40(5):1149-56. [Medline].
Feldman M. Polycholecystectomy syndrome with special reference to the cystic duct remnant. Gastroenterology. 1958;34:239.
Garlock JH, Hurwitt ES. The cystic duct stump syndrome. Surgery. 1951;29:833.
Gieslak AK, Stout AP. Traumatic and amputation neuromas. Arch Surg. 1946;53:646.
Glenn F, Johnson Jr G. Cystic duct remnant, a sequela of incomplete cholecystectomy. Surg Gynecol Obstet. Sep 1955;101(3):331-45. [Medline].
Graham EA, Mackey WH. A consideration of the stoneless gallbladder. JAMA. 1934;103:1497-9.
Gray HK, Garrett Jr CM. Obstruction of the duodenum beyond the ampulla of Vater; a possible cause of symptoms suggesting disease of the biliary tract. Ann Surg. Sep 1955;142(3):532-6. [Medline].
Gray HK, Sharpe WS. Biliary dyskinesia: role played by remnant of cystic duct. Mayo Clinic. 1944;19:164-8.
Grimson KS, Hesser FH, Kitchen WW. Early clinical results of transabdominal celiac and superior mesenteric ganglionectomy, vagotomy, or transthoracic splanchnicectomy in patients with chronic abdominal visceral pain. Surgery. 1947;22:230.
Halligan EJ, Rohim F. Transcutaneous hepatic cholangiographic study: its importance in the diagnosis and management of biliary disease. J Int Coll Surg. Feb 1959;31(2):154-60. [Medline].
Hase T, Kodama M, Shibata J, Kurumi Y, Kishida A, Kawaguchi A, et al. Three-dimensional helical computed tomography with intravenous cholangiography for sclerosing cholangitis manifested as postcholecystectomy symptom. J Clin Gastroenterol. Apr 1997;24(3):169-72. [Medline].
Heffernon EW, Milhon WA, Roxen SW. Irritable colon and gallbladder disease. JAMA. 1960;173:1.
Hicken NF, McAllister AH, Walker G. The problem of retained common duct stones. Am J Surg. 1959;97:173.
Hicken NF, McAllister AJ, Call DW. Residual choledochal stones: etiology and complications in 110 cases. Arch Surg. 1954;68:643.
Hicken NF, White LB, Coray QB. External biliary fistulas: a study of 23 cases. SG&O. 1942;74:828.
Hinkel CL, Miller GA. Correlation of symptoms, age, sex, and habitus with cholecystographic findings in 1000 consecutive examinations. Gastroenterology. 1957;32:807.
Imamoglu K, Perry Jr JF, Wangensteen OH. Experimental production of gallstones by incomplete stricture of the common bile duct. Surgery. 1957;42:623.
Iszak FC. The postcholecystectomy syndrome: its prevention and treatment by choledochoduodenostomy. J Intern Coll Surg. 1958;30:802.
Ivy AC, Sanbloom P. Biliary dyskinesia. Ann Int Med. 1934;8:115-22.
Judd ES. Clinical versus pathologic cholecystitis. Coll Papers Mayo Clinic. 1925;17:152-6.
Kaplan IW. Operative cholangiography. Am J Gastroenterology. 1955;23:547.
Kourtas B, Tobler A. The postcholecystectomy syndrome on the basis of late results in 551 cases followed up during years 1950-1955. Chirug. 1959;30:398.
Lamari TK, Fock G. Cystic duct remnant; a cause of biliary distress following incomplete cholecystectomy. Acta Chir Scandinav. 1958;114:361.
Lester LJ, Colp R. Treatment of biliary dyskinesia with special reference to sphincterotomy. AMA Arch Surg. 1952;64:168.
Madura JA, Madura JA 2nd, Sherman S, Lehman GA. Surgical sphincteroplasty in 446 patients. Arch Surg. May 2005;140(5):504-11; discussion 511-3. [Medline].
McClenahan JE, Evans JA, Braunstein PW. Intravenous cholangiography in the post cholecystectomy syndrome. JAMA. 1955;159:1353.
McHardy G. Postcholecystectomy syndrome disturbances in gastrointestinal motility. Springfield IL: Thomas; 1959:194.
Mergener K, Clavien PA, Branch MS, Baillie J. A stone in a grossly dilated cystic duct stump: a rare cause of postcholecystectomy pain. Am J Gastroenterol. Jan 1999;94(1):229-31. [Medline].
Meyers SG, Sandweiss DJ, Saltzstein HC. End results after gallbladder operations with analysis of causes of residual symptoms. Am J Digest Dis. 1938;5:667.
Miller GH. The re-formed gallbladder. J OK MA. 1945;38:1.
Mirizzi PL. La Cholangiografia Durante las Operaciones de la Vias iliares. Bol y Trab Soc. Cir De Buenos Aires. 1932;16:1133.
Morton CB 2nd. Post-cholecystectomy symptoms from cystic duct remnants. Ann Surg. May 1954;139(5):679-82. [Medline].
Mueler GP. The noncalculus gallbladder. JAMA. 1927;89:786-9.
Pribam BOC. The method for dissolution of common duct stones remaining after operation. Surgery. 1947;142:1262.
Pribram BOC. Postcholecystectomy syndromes. JAMA. 1942;40:1262.
Puestow CB. Changes in intracholedochal pressure following cholecystectomy. SG&O. 1938;67:82-6.
Raymer JB, Tarpinian DA, Myers SG. Symptoms following cholecystectomy. Am J Digest Dis. 1960;67:82-6.
Ruffin J. Further observations on the use of 1131 labeled lipids in the study of disorders of the gastrointestinal tract. Gastroenterology. 1958;34:484.
Sadah HA. Post-cholecystectomy biliary pain and dyspepsia. J OK State Med Assoc. 1994;87:316-8.
Schrager VL, Ivy AC. Symptoms produced by distention of the gallbladder and biliary ducts. SG&O. 1928;47:1-13.
Sherlock S. Diseases of the liver and biliary system. Charles C. Thomas, Publisher. 1955.
Shingleton WM, Peete WPJ. The postcholecystectomy syndrome. Am Surg. 1962;28:19-31.
Smioth ML, Santos M. Biliary radiomanometery. US Armed Forces MJ. 1959;8:481.
Smith SW, Engel C, Averbook B. Problems of retained and recurrent common bile duct stones. JAMA. 1957;164:231.
Snape WJ, Friedman MHF, Swenson PC. Correlation between cholecystogram and secretin test for gallbladder function. Am J M Sc. 1948;216:188.
Walters W. Postcholecystectomy dyskinesia; with pancreatitis, sphincteritis, and choledocholithiasis as causes. J Am Med Assoc. Feb 11 1956;160(6):425-31. [Medline].
Weir JF, Snell AM. Symptoms that persist after cholecystectomy. JAMA. 1935;105:1093-8.
Westphal K. Muskelfunktion, nervensystem und pathologie der Gallenwege. Ztschr f klin Med. 1923;96:22-50.
Whipple AO. Surgical criteria for cholecystectomy. Am J Surg. 1926;40:129-31.
Wise RE, O'Brien RG. Interpretation of the intravenous cholangiogram. J Am Med Assoc. Mar 10 1956;160(10):819-27. [Medline].
Womack NA, Siegert RB. Surgical aspects of lesions of Meckel's diverticulum. Ann Surg. Aug 1938;108(2):221-36. [Medline].
postcholecystectomy syndrome, cholecystectomy, post cholecystectomy, ERCP post cholecystectomy syndrome, ERCP procedure, MRCP, endoscopic ultrasound, sphincter of Oddi, endoscopic retrograde cholangiopancreatography, post-cholecystectomy syndrome, postcholecystectomy symptoms, post cholecystectomy symptoms, post-cholecystectomy symptoms, gastroesophageal reflux disease, GERD, peptic ulcer disease, choledochotomy, magnetic resonance cholangiopancreatography, MRCP, percutaneous transhepatic cholangiography, intraoperative cholangiogram, esophagogastroduodenoscopy
Steen W Jensen, MD, Chief, Department of Surgery, Plumas District Hospital
Steen W Jensen, MD is a member of the following medical societies: American College of Surgeons and California Medical Association
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Oscar Joe Hines, MD, Assistant Professor, Department of Surgery, University of California at Los Angeles School of Medicine
Oscar Joe Hines, MD is a member of the following medical societies: Alpha Omega Alpha, American Association of Endocrine Surgeons, American College of Surgeons, Association for Academic Surgery, Society for Surgery of the Alimentary Tract, and Society of American Gastrointestinal and Endoscopic Surgeons
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Amy L Friedman, MD, Professor of Surgery, Director of Transplantation, State University of New York Upstate Medical University College of Medicine, Syracuse
Amy L Friedman, MD is a member of the following medical societies: American College of Surgeons, American Medical Association, American Medical Women's Association, American Society for Artificial Internal Organs, American Society of Transplant Surgeons, American Society of Transplantation, Association for Academic Surgery, Association of Women Surgeons, International College of Surgeons, International Liver Transplantation Society, New York Academy of Sciences, Pennsylvania Medical Society, Philadelphia County Medical Society, Society of Critical Care Medicine, and Transplantation Society
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Michael E Zevitz, MD, Assistant Professor of Medicine, Finch University of the Health Sciences, The Chicago Medical School; Consulting Staff, Private Practice
Michael E Zevitz, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians, American Medical Association, and Michigan State Medical Society
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John Geibel, MD, DSc, MA is a member of the following medical societies: American Gastroenterological Association, American Physiological Society, American Society of Nephrology, Association for Academic Surgery, International Society of Nephrology, New York Academy of Sciences, and Society for Surgery of the Alimentary Tract
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Gail Stentzel for her help in keeping me organized and in assisting with data collection. Jan, my wife, for her love and patience.
Further ReadingRelated eMedicine topics:
Bile Duct Strictures
Biliary Colic
Biliary Disease
Bile Duct Tumors
Cholangitis, Primary Sclerosing
Cholelithiasis [Emergency Medicine]
Cholelithiasis [Gastroenterology]
Cholelithiasis [Pediatrics: General Medicine]
Cholelithiasis [Radiology]
Gallbladder Disease
Clinical guidelines:
ACR Appropriateness Criteria® right upper quadrant pain. American College of Radiology - Medical Specialty Society. 1996 (revised 2007). 5 pages. NGC:006992
ASGE guideline: the role of ERCP in diseases of the biliary tract and the pancreas. American Society for Gastrointestinal Endoscopy - Medical Specialty Society. 2005 Jul. 8 pages. NGC:004486
Quality indicators for endoscopic retrograde cholangiopancreatography. American College of Gastroenterology - Medical Specialty Society
American Society for Gastrointestinal Endoscopy - Medical Specialty Society. 2006 Apr. 6 pages. NGC:004967
Clinical trials:
Adjunct Sedatives in Procedures Involving Endoscopic Ultrasound (EUS) and Endoscopic Retrograde Cholangiopancreatography (ERCP)
A Trial of Aprepitant For Prevention of Post-Endoscopic Retrograde Cholangiopancreatography (ERCP) Pancreatitis
Study of Pain Perception Between Males and Females Following Laparoscopic Cholecystectomy
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