Pseudo-obstruction of the Common Duct in Operative Cholangiography of contrast media into the duodenum may be spasm of the sphincter of Boyden and is a diagnostic problem in operative cholangiography. Chessick et al (see pp 53-57) have alerted the surgeon to the possible etiologic role of fentanyl. If fentanyl is found to directly induce or potentiate spasm in a majority of patients, an alternative anesthetic may be advised during biliary surgery. As Chessick et al also point out, however, there are many variables in operative cholangiography and a number of these might induce spasm. In 56 postcholedo-

Nonpassage by well-recognized caused

chotomy cholangiograms reported by Ginzburg et al,1 no duodenal drainage was seen in 24 (43%), but subsequent postoperative T-tube cholangiography was normal for all of these patients. No mention was made of the anesthetic used. Baker2 has noted a 25% incidence of pseudo-obstruction after common duct instrumentation. Such high inci-

dences of apparent obstruction due to spasm and such a variation in incidence underscore the problem in incriminating a single factor as the sole cause. In addition, the "bird-beaked appearance" is not the only sign seen with spasm. The pseudocalculus sign may also be seen with spasm of the terminal duct and on a single x-ray film may be indistinguishable from the menis¬ cus seen with a stone (giving a false-positive examina¬ tion). ' ' This well-recognized phenomenon, although usu¬ ally transient, may be persistent. In the cases presented by Chessick et al, further cho¬ langiograms might have shown drainage into the duode¬ num. In one of the two cases where a second operative cholangiogram was performed, the injection pressure was increased. In discussing the pseudocalculus sign and spasm, Beneventano and Schein have noted that "the du¬ ration of this disturbing roentgen image is further prolonged when the contrast is injected at even higher '

pressures in

tion." These the cm

an

attempt to overcome the assumed obstruc¬

authors, in another article,' found that opening pressure of the sphincter of Oddi was only 13 H20. same

For these reasons, apparent obstruction seen on an op¬ erative cholangiogram should be followed by a second study with the same injection pressure. Also, it should be borne in mind that fluoroscopy can usually provide the cor¬ rect diagnosis at postoperative T-tube cholangiography. If at that time the diagnosis of retained calculus is made, it is possible to remove the stone under fluoroscopic guidance with a stone-retrieval basket." Finally, the radiologist should always be considered as a consultant and should be available to render immediate interpretations during the operative procedure, just as a pathologist might be called on to give a reading on a frozen section. FRANCIS J. SCHOLZ, MD Department of Radiology Peter Bent Brigham Hospital 721 Huntington Ave Boston, MA 02115 References 1. Ginzburg L, Geffen A, Friedman IH: Pseudo-obstruction following post-choledochotomy cholangiography. Ann Surg 166:83\x=req-\

90, 1967.

2. Baker JW, in discussion, Way LW, Admirand WH, Dunphy JE: Management of choledocholithiasis. Ann Surg 176:347-359, 1972. 3. Beneventano TC, Schein CJ: The pseudocalculus sign in cholangiography. Arch Surg 98:731-733, 1969. 4. Scholz FJ, Wise RE: T-Tube cholangiography: Technical considerations for the surgeon. Surg Clin North Am 53:435-443,1973. 5. Schein CJ, Beneventano TC: Biliary manometry. Surgery 67:255-260, 1970. 6. Burhenne HJ: Nonoperative retained biliary tract stone extraction: A new roentgenologic technique. Am J Roentgenol Radium Ther Nucl Med 117:388-399, 1973.

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