New observations on the cholangiographic pseudocalculus defect: a case report.

Contraction of the distal sphincter of the common bile duct (as distinct from the sphincter of Oddi) may produce a pseudocalculus defect. A typical case is described where the defect was thought to be a retained stone on T-tube cholangiography. The anatomy of the defect is emphasized by its persistence after sphincteroplasty. A diagnostic feature is the immediate abolition of the defect by hyoscine butylbromide (Buscopan, Boehringer Ingelheim).