Predicting common bile duct lithiasis: Determination and prospective validation of a model predicting low risk

Predicting Common Bile Duct Lithiasis: Determination and Prospective Validation of a Model Predicting Low Risk R6mi Houdart, MD, Thierry Perniceni, MD, Bernadette Darne, MD, Marcel0 Salmeron, MD, Jean-Franqois Simon, MD, Paris, France

BACKGROUND:The aim of this two-part prospective study was: (1) to identify simple, noninvasive, preoperative factors associated with low or very low risk of common bile duct lithiasis (CBDL); and (2) to test the validity of the statistical model obtained during Part One by the postcholecystectomy follow-up of patients classified into a low-risk group. PATIENTSAND MEI-HODS: In Part One of the study, preoperative clinical, biologic, and ultrasonographic data, and intraoperative cholangiographic findings were collected from 503 consecutive patients undergoing cholecystectomy for symptomatic lithiasis from 1985 to 1989. Using the data obtained in Part One, a linear logistic model was used prospectively in Part Two to determine the prediction of absence of CBDL in 279 consecutive patients. No jaundice, normal transaminase levels, common bile duct (CBD) diameter <8 mm, and no intrahepatic duct enlargement defined the low-risk group of CBDL. RESULTS: In Part One, CBDL was present in 84 (17%) of all patients. Five parameters were used to classify 73% of all patients as low risk of CBDL and 27% as high risk. In the low-risk groups, CBDL was present in 1% of 118 cases with acute gallbladder complications, and 5% of 250 cases with no acute gallbladder complications. In Part Two, 171 (61%) patients were classified in the low-risk group (Group l), and CBD stones were not sought by any additional preoperative investigations or intraoperative cholangiography (IOC). One hundred eight patients (39%) were considered at risk of CBDL (Group 2). Mean follow-up was 20.6 months (median 19); 2 patients (1%) in the low-risk group presented a symptomatic retained stone.

From the Service de Chirurgie Viscerale, Hopital de La Croix Saint-Simon, Paris, France. Requests for reprints should be addressed to Remi Houdart, Service de Chirurgie Visdrale, Hopital de La Croix Saint-Simon, 125, rue d’Avron 75960 Parts, France. Manuscript submitted December 17, 1993 and accepted in revised form August 9, 1994.

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CONCLUSIONS: This study validated this simple model for predicting risk of CBDL and avoiding invasive preoperative investigations-as well as IOC-in more than 60% of symptomatic cholelithiases. In addition, this model seemed useful for defining patients in whom further exploration for CBDL was justified, since 42 (39%) of the 108 Group 2 patients were proved to have CBDL. Am J Sutg. 1995;170:38-43.

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ommon bile duct lithiasis (CBDL) is present in 10% to 20% of patients undergoing surgery for biliary lithiasis,‘s* the diagnosis being classically made by routine intraoperative cholangiography (IOC). However, it is often proposed that cholangiography be reserved for a selected population at high risk of CBDL,3 essentially to reduce operating time, costs, and unnecessary exploration of the common bile duct (CBD). Therefore, criteria permitting the classification of patients undergoing cholecystectomy as being at either high or low risk of CBDL would be useful. The advent of laparoscopic cholecystectomy increases this need, since IOC is not always possible4 and laparoscopy does not always allow CBDL treatment when present. It is, therefore, preferable to know the state of the CBD before intervention. However, there are few prospective studies regarding this subject using current diagnostic techniques. The two-part study presented here addresses this issue. The aim of Part One is to examine simple, preoperative predictors that might allow the identification of patients at low or very low risk of CBDL. Part Two tests the statistical model obtained during Part One by the postcholecystectomy follow-up of patients classified into a low-risk group.

METHODS Part One From October 1985 to October 1989 in one surgical unit, and from October 1988 to October 1989 in three other surgical units, all patients to undergo cholecystectomy for symp tomatic cholelithiasis were included in this study. Preoperative and intraoperative data were documented systematically and prospectively. Exclusion criteria included: cirrhosis, cholecystectomy performed during other interventions, biliary tumor-related lithiasis, and cases of retained stones after cholecystectomy. Thirteen different kinds of data were collected for each patient. The clinical data collected included: the patient’s gender; age; the presence of acute or chronic biliary colic; acute gallbladder complications (ie, acute cholecystitis or hydrocJULY 1995

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holecystis); gallstone migration (ie, intense TABLE I epigastric pain, pancreatitis); recent or curCharacteristics of the Patients With and Without CBDL rent jaundice; and cholangitis. UltrasonPatients Patients Without CBDL With CBDL ographic data were used to distinguish pan rl (%) PValue (“~) tients with a CBD diameter greater than 8 419 (83) 84 Total patients (17) mm from those with a CBD diameter equal Clinical data to or less than 8 mm, and to distinguish pa102 (24.3) 25 0.297 (29.8) Male tients with dilated intrahepatic ducts from 4 (0.9) 28 (33.3j 0.001 Jaundice those without. The biologic data collected 142 (33.9) 15 (17.9) 0.004 Acute gallbladder disease included serum bilirubin, alkaline phos28 (6.7) 17 (20.2) Migration phatase, aspartate and alanine transaminase 11 (2.6) 29 (34.5) 8 mm cystic duct and controlled-pressure perfusion 29 (34.5)
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Table II shows each parameter’s sensitivity, specificity, PPV, and NW regarding CBDL prediction. For example, 50% of patients with abnormal AST or ALT values Total Sensitivity Specificity PPV NPV (n = 503) n (%) n (%) n (“IO) n (%) and 73% with CBD >8 mm had CBDL, Clinical data whereas 93% of patients with normal AST Female 376 59 (70) 102 (24) 59 (16) 102 (80) or ALT values and 91% with CBD ~8 mm Male 127 25 (30) 317 (80) 25 (20) 317 (84) had normal ducts. Jaundice 32 28 (33) 415 (99) 28 (87) 415 (88) Regression analysis selected five variables Acute gallbladder disease 157 15 (18) 277 (66) 15 (10) 277 (80) that allowed the best prediction of CBDL: Migration 45 17 (20) 391 (93) 17 (38) 391 (85) jaundice, acute gallbladder disease, transCholangitis 40 29 (35) 408 (97) 29 (78) 408 (88) aminase values, CBD diameter, and size of Biologic data intrahepatic bile ducts (Table III). Among Abnormal AST or ALT 113 56 (67) 362 (86) 56 (50) 362 (93) Abnormal amylase 41 12 (14) 389 (93) 12 (29) 389 (84) the groups individualized by these 5 variAbnormal ALP 99 55 (65) 375 (89) 55 (56) 375 (93) ables, only 2, presence and absence of acute Abnormal bilirubin 76 48 (57) 39 (93) 48 (63) 39 (92) gallbladder disease, included more than 30 Ultrasonographic data patients with a low risk; in these 2 groups, CBD >8 mm 60 44 (52) 403 (96) 44 (73) 403 (91) the predicted prevalences of CBDL were Enlarged IHD 31 29 (35) 417 (99) 29 (94) 417 (88) 2% and 6%, respectively (Table IV). Thirteen cases of CBDL were found in paCBDL = common bile duct lithiasis; PPV = positive predictive value; NPV = negative predictive value: AST = aspartate transaminase: ALT = alanine transaminase: ALP = alkaline phostients classified in 1 of the 2 lowest risk phatase; CBD = common bile duct; Ih’D = intrahepatic ducts. groups: 1 (1%) case from 116 acute gallbladder complications and 12 (5%) cases TABLE Ill from 250 not having acute gallbladder complications. The Results of the Backward Step Procedure (Logistic Model) number and size of these CBD stones are presented in the Standard Odds Figure. Eight of the 13 cases involved only 1 to 4 stones ~3 Ratio /3 Error mm in diameter. TABLE

II

Sensitivity, Specificity, and Positive and Negative Predictive Values for CBDL Prediction

J

Abnormal AST or ALT Jaundice Acute gallbladder disease Enlarged IHD CBD >8 mm

1.61 2.81 -1.19 2.61 2.18

0.36 0.65 0.45 0.94 0.48

5.02 16.66 0.30 13.57 8.9

AST = aspartate transaminase; ALT = alanine transaminase; hepatic ducts; CBD = common bile duct.

IHD = intra-

tients and 108 (39%) Group 2 patients. In Group 1, there were 137 laparoscopic cholecystectomies and 34 conventional laparotomy cholecystectomies, essentially for severe gallbladder empyema. There were 123 elective and 48 emergency interventions. IOC was performed in 22 cholecystectomies (3 laparoscopic, 19 laparotomy) to better define bile duct anatomy in the presence of major inflammatory changes-not to seek CBDL.

RESULTS Part One

Results for all centers are shown together, as no differences between centers were observed. CBDL was present and treated (stone removal) in 84 (17%) patients with a mean age of 64.1 years (SD 18.8). Subjects without CBDL had a mean age of 59.6 years (SD 16.8, P = 0.03). The characteristics of patients with and without CBDL are shown in Table I. Cholangiography revealed CBDL in 82 of 84 patients (98%) and missed 2 cases (1 and 2 stones 1 mm in diameter, respectively). These 2 cases were discovered by systematic surgical exploration of the CBD that was performed because of clinical context. Four false-positive cholangiographies led to surgical exploration, and 10 of 12 systematic surgical explorations of the CBD discovered no stone. 40

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Part Two All 22 IOCs performed in Group 1 patients were normal, and, in Group 2, CBD stones were proved by surgical exploration in 42 (39%) of the 108 patients. Postoperatively, 3 asymptomatic patients in Group 1 were lost to follow-up: 2 patients were lost at 1 and 6 months, respectively, because they moved out of the region; and 1 patient was lost at 3 months because of death from unrelated pathology. Therefore, 168 patients in Group 1 were followed up from 1 to 38 months (mean 20.6, median 19). Postoperative symptoms of possible biliary origin led to further investigations in 9 patients in Group 1. Morphologic biliary investigations were normal in 7 patients who had no symptom recurrence during further follow-up, and, in 2 cases, these symptoms were stone related. One case of jaundice 13 months postoperatively was due to a retained stone in the cystic duct in a female patient who initially underwent emergency cholecystectomy by laparotomy (Mirizzi syndrome). In the other patient with stone-related symptoms, who was initially treated electively, pain recurring in the 23rd postoperative month without biologic or ultrasonographic abnormalities revealed CBDL, which was treated by endoscopic sphincterotomy. Therefore, 2 (1%) of the 171 patients classified at low risk of CBDL presented a symptomatic retained stone, but there was only 1 (0.6%) case of CBDL.

COMMENTS Selective rather than routine IOC is only justified if patient groups at low risk of CBDL have been clearly defined, and if the test of time has validated this policy in a significant series. The aim of Part One of this study was to identify those patients at low risk of CBDL. At least 21 studies JULY 1995

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TABLE IV

No. of Patients

Risk of CBDL According to the Five Parameters Selected Groups With More Than 30 Patients Acute Gallbladder Risk of CBDL Disease Predicted Jaundice Observed

116 250

0.01 0.05

GBDL= c~mrn~nbile

0.02 0.06

duct iithfasis; AST = aspartate

by the Backward Step Procedure: at Low Risk Abnormal AST or ALT

Yes No

No No transaminase:

No No

ALT = alanIne transaminase:

concerning this topic have appeared in the English-language literature in the past decade, h-z7indicating an interest in this research; however, only rarely are certain rules that are mandatory, in the authors’ opinion, observed by these researchers. First, data collection must be prospective; however, only 7 of the 2 1 studies satisfy this criterion. 6-3,14,17,21.22Also, results must provide a simple, easy-to-memorize formula. Therefore, it seems inappropriate to establish scores, as certain researchers have done,25 because even if they are more sophisticated than a simple formula, they are not practical and are not used in everyday practice. Second, a good predictor must be easily obtained, usable by all practitioners, noninvasive, inexpensive, current, and applicable to emergency cases. Therefore, intravenous cholangiography was ruled out, even though some practitioners use it routinely.” It is an onerous investigation that is inappropriate for emergenciesz9-31 and has weak sensitivity (22% in a recent prospective study).32 We, therefore, selected current clinical, biologic, and ultrasonographic criteria. Our results show the value of these predictors (Table II), especially regarding specificity. The value of our biologic criteria has been mentioned in the literature,“,lh.l’Y,??but all studies have not indicated the predictive value of transaminase levels. The results of Anciaux et al” confirm this; they noted AST and ALT elevation in 72% and 81 v/oof cases of symptomatic CBDL. Conversely, Lacaine et al” did not find any predictive value for transaminase levels. Astonishingly, to our knowledge, no study has taken preoperative ultrasonographic data into account; whereas, our results show its predictive value, not so much by direct CBDL visualization as by CBD diameter measurement. Moreover, it has been shown that while ultrasonography cannot compete with a specific technique, such as ERG’, for detecting CBDL, it can determine CBD diameter just as accurately.j3 Numerous studies excluded emergencies or considered a priori that, compared to elective situations, acute cholecystitis increased the chances of CBDL. However, our results show that, although the risk was high for cholecystitis (18%) considered all together, 74% of cholecystitis patients had a very low risk of CBDL, less than 2%. These patients were defined by four parameters: no jaundice, normal transaminase levels, CBD diameter ~3 mm, and no intrahepatic duct enlargement. Third, the risk of CBDL must be assessable preoperatively. Risk evaluation must be assessable exclusively on preoperative factors and not be based on a mixture of preoperative and intraoperative factors, as is the case in numerous

CBD z-8 mm

Enlarged IHD No No

No No

CBD = common bile duct, IHD = fntrahepathz ducts.

10 0 9 8

2

00

1

0 1

0

0

0

0 2

3

4 Size

5

6

0 i

II

of Stones (mm)

Figure. Characteristics (size and number) of stones discovered in 13 patients in the two low-risk groups.

So, with the very simple equation: no jaundice, normal transaminase levels, CBD diameter ~8 mm, and no intrahepatic duct enlargement on conventional ultrasonography, 73% of all cases, elective or emergency, were classified as being at low risk of CBDL. The risk was less than 2% and 6%, respectively, for acute gallbladder complications and elective patient groups. Is this risk low? Can it be deliberately ignored? This boils down to the question: what would happen to patients in whom stones were left in the CBD? Of course, there is no direct answer to this question, since the natural history of asymptomatic CBDL is unknown. Nevertheless, several clues allow us to postulate that many would remain asymptomatic. In this study, 8 of the 13 CBDL cases discovered in the lowrisk group had single or very few calculi, which were small in size (52 mm). Certain retrospective studies,‘*J3~‘” with variable follow-up periods of 1 to 5 years, and 1 prospective study,” with minimum follow-up of 1 year, showed that only 0% to 1% of patients in whom IOC was not performed because of low risk of CBDL presented a retained stone. In a recent prospective study by Voyles et al,j4 which had a maximum follow-up of 9 months and excluded cholecystitis, no retained stones were observed in 223 patients with no history of pancreatitis, no jaundice, normal liver function tests, and CBD diameter 15 mm. Finally, autopsy studies have revealed cases of asymptomatic CBDL.” Therefore, it seems reasonable to think that CBDL would cause symptoms in

stu~ies,h,7.14,17,~l,~~,~i

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only 1% to 2% of low-risk patients undergoing surgery without performing IOC and detecting CBDL. Part Two validates the model and confirms our estimations. Of the two presentations of retained stone, one occurred in a patient with acute cholecystitis; the retained stone had been inadvertently left in situ in the cystic duct at the time of dissection by a surgeon relatively inexperienced with the laparoscopic technique. Our percentage of retained symptomatic CBDL, after 20.6 months in 171 pa-

tients, was only 0.6%. It must be noted, however, that CBDL has been known to present 23 months after surgery, so definitive conclusions cannot yet be drawn. The delay in expression of retained CBDL can certainly be greater than 3 years, but the long term follow-up of asymptomatic surgical patients who have benign, common pathology is difficult; thus, it is unrealistic to expect to follow up a large cohort completely for more than 3 years. Moreover, the published figures for retained stones after laparoscopic cholecystectomy, whether with36 or without* selective cholangiography, only take into account the immediate postoperative period. In the study presented, the model classified 61% of all patients undergoing cholecystectomy for cholelithiasis as being at low risk of CBDL; 39% were considered at risk. In fact, CBDL was present in 39% of these at-risk patients. Therefore, it is possible to define, for more than 60% of patients undergoing surgery for cholelithiasis, a postoperative risk of symptomatic CBDL of the order of 1% based only on preoperative clinical examination, serum ALT and AST levels, and conventional ultrasonography. Murison et aP7 found a similar figure, although in a higher risk group. It therefore seems advisable to avoid further diagnostic preoperative investigations, and even routine IOC, unless necessary for anatomic reasons3* in patients with absence of jaundice, normal AST and ALT levels, and ultrasonographic evidence of a normal biliary tract (ie, CBD under 8 mm) even in the presence of cholecystitis. On the other hand, the exploration of the group at risk seems necessary, to know before the intervention if the CBD is free or not of stones and the disposition of the stones when present. This would facilitate the preoperative choice of technique (ie, laparotomy, endoscopic sphincterotomy and laparoscopic cholecystectomy, or laparoscopic exploration of the CBD). REFERENCES 1. National Institutesof Health. Consensusdevelopmentconference statementon gallstonesand laparoscopiccholecystecromy.Am .J Surg. 1993;165:34@398. 2. The Southern Surgeons Club. A prospectiveanalysisof 1,5 18 laparoscopic cholecystectomies. NEJM. 1991;32+1073-1078. 3. Gerber A. A requiem for the routine operative cholangiogram. Surg Gynecol Obstet. 1986;163:363-364. 4. McEntes G, Grace PA, Boucher-Hayes D. Laparoscopic cholecystectomy and the common bile duct. BrJ Surg. 1991;78:385-386. 5. Hosmer DW, Lemeshow S. Applied Logistic Regression. New York, NY: John Wiley & Sons; 1989. 6. Reiss R, Deutsch AA, Nudelman I, Kott I. Statistical value of various clinical parameters in predicting the presence of choledochal stones. Surg Gynecol Obstet. 1984;159:273-276. 7. Hauer-Jensen M, Karesen R, Nygaard K, et al. Predictive ability of choledocholithiasis indicators. A prospective evaluation. Ann Surg. 1985;202:6+68.

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8. Lacaine F, Corlette MB, Bismuth H. Preoperative evaluation of the risk of common bile duct stones. Arch Surg. 1980;115:114-116. 9. Anciaux ML, Pelletier G, Attali P, et al. Prospective study of clinical and biochemical features of symptomatic choledocholithiasis. Dig Dis Sci. 1986;31:449-453. 10. Pemthaler H, Sandbicher P, Schmid TH, Margreiter R. Operative cholangiography in elective cholecystectomy. Br ] Surg. 1990;77: 399-400. 11. Holmin T, Jonsson B, Lingren B, et al. Selective or routine intraoperative cholangiography: a cost-effectiveness analysis. World J Surg. 1980;4:315-322. 12. Grogono JL, Woods WGA. Selective use of operative cholangiography. World J Surg. 1986;10:1009-1013. 13. Gregg RO. The case for selective cholangiography. Am J Surg. 1988;155:540-545. 14. Deitch EA, Voci VE. Operative cholangiography. The case for selective instead of routine operative cholangiography. Am Surg. 1982; 48:297-301. 15. Bogokowsky H, Slut&i S, Zaidentstein L, et al. Selective operative cholangiography. Surg GynecoI Obster. 1987;164:124-126. 16. Levine SB, Lemer HJ, Leifer ED, Lindheil SR. Intraoperative cholangiography. A review of indications and analysis of age-sex groups. Ann Surg. 1983;198:692-698. 17. Mansberger JA, Davis JB, Scarborough C, Bowden TA. Selective intraoperative cholangiography. A case for its use on an anatomic basis. Am Surg. 1988;54:3 l-33. 18. Pasquale MD. Selective vs routine use of intraoperative cholangiogmphy. An argument. Arch Surg. 1989;124:1041-1042. 19. Mazaheri Seif R. Routine operative cholangiography: a critical appraisal. Am J Surg. 1977;134:566-568. 20. Mills JL, Beck DE, Harford J Jr. Routine operative cholangiography. Surg Gynecol Obstec. 1985;161:343-345. 21. HauersJensen M, Karesen R, Nygaard K, et al. Consequences of routine peroperative cholangiography during cholecystectomy for gallstone disease: a prospective, randomized study. World J Surg. 1986; 10:996-1002. 22. Wilson TG, Hall JC, Watts JM. Is operative cholangiography always necessary? Br J Surg. 1986;73:637-640. 23. Kitahama A, Kerstein MD, Overby JL, et al. Routine intraoperative cholangiogram. Surg Gynecol Obstet. 1986;162:317-333. 24. Taylor m, Torranle B, Rimmer S, et al. Operative cholangiogra phy: is there a statistical alternative? Am J Surg. 1983;145:640-643. 25. Hyguier M, Bomet P, Charpak Y, et al. Selective contraindications based on multivariate analysis for operative cholangiography in bilialy lithiasis. Surg Gynecol Obst. 1991;172:47&474. 26. Del Santo P, Azarian KK, Rogers F, et al. Prediction of cholangiography in patients undergoing elective cholecystectomy with routine liver function chemistries. Surgery. 1985;98:7-11. 27. Pagana TJ, Stahlgren LH. Indications and accuracy of operative cholangiography. Arch Surg. 1980;115:1214-1215. 28. Dubois E Indications for laparoscopic cholecystectomy in 1991. Gastmenterol Cfin Biol. 1991;15:421423. 29. Eubanks B, Martinez CR, Mehigand D, Cameron JL. Current role of intravenous cholangiography. Am J Surg. 1982;143:731-733. 30. Alinder G, Nilsson U, Lunderquist A, et al. Preoperative infusion cholangiography compared to routine operative cholangiography at elective cholecystectomy. Br J Surg. 1986;73:383-387. 3 1. Goodman MW, Ansel HJ, Vennes JA, et al. Is intravenous cholangiography still useful? Gasnoenterofogy. 1980;79:642&45. 32. Houdart R, Brisset D, Pemiceni T, Palau R. Intravenous cholangiography is not indicated before cholecystectomy for Iithiasis. A prospective study of 100 cases. Gastioenterol Clin Biol. 1990;14: 652-654. 33. Espinoza P, Kunstlinger F, Liguory C, et al. Accuracy of ultrasonography for the diagnosis of choledocolithiasis. Gnstroenterol Clin B&l. 1984;8:42_46. 34. Voyles CR, Petro AB, Meena AL, et al. A practical approach to

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laparoscopic cholecystectomy. Am .I Sag. 1991;161:365-370. 35. Grump C. The incidence of gallstones and gallbladder disease. Surg G_vnecol Obstet. 1931;53:447-455. 36. Lillemoe KD, Yeo CJ, Talamini MA, et al. Selective cholangiog raphy. Current role in laparoscopic cholecystectomy. Ann Surg. 1992; fk669-676. 37. Murison MSC, Cartel1 PC, MC Ginn FP. Does selective peroperative cholangiography result in missed common bile duct stones? Br / Surg. 1989;76:1343. Abstract. 38. Berci G. Sacrier JM, Paz-Partlow M. Routine or selected intraoperative cholangiography during laparoscopic cholecystectomy. Am 1 Surg. 1991;161:355-360.

EDITORIAL COMMENT Cholecystectomy is complete only when common bile duct (CBD) stones have been either excluded or removed. The authors developed a model for evaluating the risk of CBD stones based on retrospective data in the prelaparoscopic era. Their model input includes readily available bio-

COMMON BILE DUCT LITHIASIWHOUDART

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chemical, radiologic, and clinical parameters in the preoperative period. A group of patients were identified in whom the risk of CBD stones was sufficiently low that confirmatory operative cholangiography was judged not to be indicated. Perhaps their model would have been even more sensitive if “low risk” were limited to only elective patients (versus those with acute cholecystitis) with a maximum CBD diameter of 5 mm (versus 8 mm). Nonetheless, the authors’ data do offer a scientific basis for the avoidance of routine operative cholangiogram in a large group of patients. The financial constraints of health care systems in all countries increase the importance of studies such as this that show how a screening examination can be limited to those at greatest risk of disease. With fewer resources, quality of care can be maintained only when the appropriateness of testing is directed by scientific methods. C. Randk Voyks, MD Jackson, Mississippi

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