Anatomic Variation in the Gallbladder Philip
M. Hatfield,
M.D., and Robert
S
INCE the anatomy of the gallbladder and bile ducts is quite variable, it is imperative that the radiologist and surgeon be alert to clinically significant deviations from the normal. The fact that we continue to seemany iatrogenic common bile duct strictures and biliary fistulas suggests that this goal, however laudable, has not been achieved. EMBRYOLOGY
The origin of the gallbladder and extrahepatic ducts is separate and distinct from that of the intrahepatic ducts and precedes it by several weeks. At the 2.5~mmstageof embryonic developmerit, a bifid bud forms along the ventral margin of the primitive foregut and proliferates laterally into the adjacent mesenchyme(the septum transversum). The more caudal of thesetwo diverticula initiates formation of the gallbladder and extrahepatic ducts and the more cranial initiates formation of the liver and intrahepatic ducts. By the S-mm stage, the originally hollow gallbladdercommon duct primordium and duodenumbecome solid, but they soon revacuolate. The common bile duct lumen is reestablishedby the 7.5-mm stage, and the gallbladder and duodenal lumens are reestablishedsomewhatlater. Portal and hepatic vein development and hepatocyte and Kupffer cell formation precede development of the intrahepatic bile ducts, the veins achieving the usual adult configuration by the 9.5-mm embryonic stage.By the l&mm stage,the intrahepatic ducts consist only of a blindly ending solid cord of cellsextending from the choledochocystic duct toward the liver hilum. Formation of the intrahepatic ducts apparently occursby induction at the point of contact of this blind-ending ductal anlagewith the liver cells.’ Philip M. Hatfield, M.D.: Radiologist, Lahey Clinic Foundation, Boston, Mass. Robert E. Wise, M.D.: Chairman, Department of Diagnostic Radiology, Lahey Clinic Foundation, and Clinical Professor of Radiology, Boston University School of Medicine, Boston, Mass. Reprint requests should be addressed to Philip M. Hatfield, M.D., Department of Diagnostic Radiology, Lahey Clinic Foundation, 605 Commonwealth Avenue, Boston, Mass. 02215. 0 1976 by Grune & Stratton, Inc. Seminars
in Roenfgenology,
Vol.
Xl,
No.
3 (July),
1976
and Bile Ducts
E. Wise, M.D.
Development of the intrahepatic ducts proceeds along the framework provided by the previously formed branches of the portal vein, which evolve through a complex sequenceof anastomoses and obliterations in the primitive vitelline plexus. Only after the venous system is establishedcan formation of the intrahepatic ducts, which follow the portal system like vines on a trellis, proceed. “While one branch of each vine winds tightly around each riser of the trellis, the main trunk and its first subdivisionsare disposedalong the basal bar of the trellis (which representsthe two trunks of the portal vein) in an entirely irregular and unpredictable manner.“’ This accounts for the marked variation in configuration of the intrahepatic ducts. Despite the opportunity for great variation during ductal development, the end result of this remarkable processis an orderly division of the liver into right and left lobes. The resulting surfacetopography is illustrated in Fig. 1. The right lobe is subdivided into superior and inferior segments, with correspondingsuperiorand inferior segmental ducts, and the left lobe is divided into medial and lateral segments.The quadrate lobe, which at one time was thought to be entirely separate,hasbeen demonstrated to be the medial segmentof the left lobe.15 Only the caudate “lobe” standsapart, receiving branches from both the right and left hepatic ducts. GALLBLADDER
Failure in formation, positioning, or septation of the cholecystic component of the primitive choledochocystic duct may occur. Ironically, agenesis of the gallbladder is of interest primarily because symptomsclosely resemblingthose of cholecystitis may develop even though the gallbladderis absent and the bile ducts appearentirely normal at operation. It is assumedto be impossibleto distinguisha nonvisualized pathologic gallbladder from agenesis preoperatively.3 About two-thirds of the lessthan 200 cases in the literature have been diagnosedat operation and one-third at autopsy. Haughton and Lewicki l3 however, have emphasizedthat rectovaginal !fistula, imperforate anus, and absenceof one or more bones are often associated,and their 757
HATFIELD
158
t-RIGHT
the
Fig. 1. Schematic liver segments
LOBE-
I-
drawing of the as seen anteriorly.
LEFT LOBE&
surface
projections
of
presence may provide, in the future, the opportunity to establish the diagnosis with ultrasound or computerized tomographic scanning, without resorting to operation. If the peritoneal reflection that maintains the gallbladder in close apposition to the undersurface of the right lobe of the liver is lax or incomplete, a mobile or floating gallbladder may result, with intermittent herniation into the lesser sac through the foramen of Winslow (Fig. 2). Other anomalies of position, such as the suprahepatic,’ retrohepatic, and left-sided5 gallbladder, are rare. At least one instance of completely separate double gallbladders, with one in the normal position and one left-sided, has been observed.*’ There is also one published example of a gallbladder in the
WISE
falciform ligament, completely separate from the liver.18 The partially or completely intrahepatic gallbladder is of interest primarily because it greatly complicates cholecystectomy. The diag nosis may be difficult to establish radiographically because unusual gallbladder orientations are not uncommon and the relationship to the liver is often indeterminable. If the diagnosis is suspected, it is readily confirmed by means of a sulfur colloid or a rose bengal scan. Should revacuolization of the primitive gallbladder be incomplete, one or more septa may result. A single transverse septum in the fundus is common (the so-called Phrygian cap deformity) as are transverse septa elsewhere in the gallbladder, but they generally are of no consequence clinically. Longitudinal septa, resulting in a double, or on rare occasion, a triple gallbladder*’ are encountered less frequently. They are not particularly significant, being subject to the same spectrum of diseases as the gallbladder that differentiates normally . In the fetus, communications are present between the gallbladder and the intrahepatic ducts through the so-called cystohepatic ducts. While these are common in the infant and newborn,” they usually regress completely by adulthood. Tiny remnants, which communicate with the intrahepatic ducts but not the gallbladder lumen, are found in l%-15% of adult gallbladders at autopsy. 8911 These so-called Luschka ducts are not demonstrable radiographically and usually cause no problem at cholecystectomy. Larger anomalous intrahepatic ducts that drain into the gallbladder occasionally occur. These may be severed at operation if unrecognized, resulting in persistent postoperative biliary fistula (Fig. 3). Hayes et a1.14 observed such communications in 14.7% of 400 biliary operations, although certainly not all were sufficiently large to produce a postoperative bile leak. CYSTIC
Fig. 2. Mobile gallbladder. Combined upper gastrointastinal examination and oral cholecystogram. The gallbladder has herniated through the foramen of Winslow into the lesser sac, so that it projects between the sacond portion of the duodenum and the gastric antrum.
AND
DUCT
Normally the cystic duct, which measures2.53.5 cm in length, inserts into the right or lateral margin of the commonbile duct at an acute angle, 2.5-3.5 cm distal to the bifurcation of the common hepatic duct. While the external union of the cystic and common bile ducts is relatively near the bifurcation of the common hepatic duct, the actual point of junction of their lumens is usually
ANATOMIC
VARIATION
somewhat more distal, most commonly 1 cm superior to the upper margin of the duodenum. Thus, as much as 4.5 cm of the distal cystic duct is often tightly bound to the common bile duct by dense fibrous tissue, so that it is obligatory that a cystic duct remnant be left at cholecystectomy if injury to the common bile duct is to be avoided.‘* A short (lo-25 mm) parallel course has been observed in 15.2% of 250 cases, and a long (greater than 25 mm) parallel course in 4.4%.” In 14% of Flint’s 200 dissections, the duct junction was located between the upper margin of the duodenum and the ampulla and ;.I 1.5% it was in the distal intramural portion, ie, within the wall of the duodenum. Unusual configurations have been observed, such as a completely separate insertion of the cystic duct into the duodenum, or a duct that first passes anterior to the duodenum before coursing beneath it to insert into the common bile duct .‘j Insertion into the right or lateral margin of the common bile duct is the rule, although exceptions are not uncommon. Anterior junction occurs in approximately 4% of cases and posterior junction in 1.5%-6.8%.10~17 In another 0.5%-l .6% of patients, the cystic duct inserts into the left or medial margin of the common bile duct. A posterior course behind the common bile duct, before insertion, is three times more common than an anterior course.17 EXTRAHEPATIC
DUCTS
The common hepatic duct constitutes that portion of the extrahepatic duct that extends from the duct bifurcation (or the junction of the right and left hepatic ducts) to the junction of the cystic duct; the common bile duct is that portion distal to the cystic duct junction. The total length of the common hepatic and common bile ducts, which averages10.2 cm, is variable, depending on body habitus and the point of insertion into the duodenum.** Usually the ducts negotiate a smoothly arcuate curve from the relatively anterior liver hilum, extending posteriorly and medially behind or just lateral to the duodenal bulb. The portion inferior to the duodenal bulb coursesthrough the head of the pancreasor lies in a groove along its anterior surface before inserting into the duodenum. In most cases(74.2%), the papilla of Vater is located along the posteromedial margin of the midportion of the descendinglimb of the duo-
Fig. 3. Anomalous hepatic duct. (A) Fistulogram. Contrast medium introduced into the postoperative cutaneous tract opacifies a subsegmental right hepatic duct. (6) T-tube cholangiogram on same patient. Opacification of the entire biliary system indicates that the anomalous duct, which drained into the neck of the gallbladder, was severed during cholecystectomy.
denurn.** A more distal insertion, at the junction of the descendingand horizontal portions of the duodenum (17%) or into the horizontal portion (S%), is not uncommon. A high insertion into the duodenal bulb or immediate postbulbar region is decidedly lesscommon. At least one example of a common bile duct emptying into the gastric antrum has been reported in the surgicalliterature.*’ Such an anomaly has never, to the best of our knowledge, been demonstratedradiographically. Unlike the gallbladder and intrahepatic ducts, clinically significant anatomic variation in the
160
HATFIELD
AND
WISE
Fig. 4. Anomalous extrahepatic ducts. (A) Operative cholangiogram. The liver and spleen are normally positioned. Because of intestinal reversal, the common bile duct crosses the midline to insert into the leftsided second portion of the duodenum. (B) Nonjunction of the right (white arrow) and left (paired straight arrows) hepatic ducts in a Mongoloid with duodenal stenosis, demonstrated by GI series. The curved arrows bracket the stenotic segment of the second portion of the duodenum. The large barium collection lateral to the bile ducts is the dilated duodenum proximal to the stenosis.
extrahepatic ducts is uncommon and is usually the result of a generalized congenital aberration rather than an isolated phenomenon confined to the bile ducts. Thus, in the case illustrated in Fig. 4A, the extrahepatic ducts are longer than normal, terminating to the left of the midline because of intestinal reversal in a patient with a normally positioned liver and spleen. In Fig. 4B, an unusually low extrahepatic junction of the right and left hepatic ducts resulted in the absence of a unified common bile duct in a Mongol with duodenal stenosis.
Variation in the configuration of the ampulla of Vater and the point of junction of the pancreatic duct with the common bile duct is frequent and accounts for the difficulty often encountered in selecting the appropriate duct during retrograde peroral cannulation. The embryologic development of these structures is exceedingly complicated.23 To summarize, multiple channels form in the wall of the duodenum at a very early stage. By coalescence of vacuoles, two channels, and then eventually one, usually prevail. The primitive am-
ANATOMIC
VARIATION
161
POST. SEGMENT
Fig. 5. Schematic drawings of the most common configuration of the segmental right and left hepatic ducts in the anterior (A) and left lateral (B) projections. Note the sharp curve of the duct of the posterior segment of the right lobe (arrows).
pullary component initially elongates so that the junction of the primitive hepatic and pancreatic ducts is gradually displaced farther from the lumen of the duodenum. This lateral migration is then reversed. A gradual re-migration back through the duodenal wall toward the lumen occurs in association with the development of the surrounding musculature, which is derived both from the wall of the duodenum and from the ducts themselves. The varying degree of this re-migration accounts for the marked differences in size of the ampulla and the location of the junction of the pancreatic and common bile ducts. In 70% of individuals, the length of the ampulla averages less than one-third (4.4 mm) that of the papilla (14.7 mm).24 In 30%40% of patients, the primitive hepatopancreatic ducts fail to unite so that two separate but immediately adjacent papillary orifices result, and the ampulla is entirely absent.2’24 In 3.4%, widely separated orifices are present in the papilla.* Rarely, re-migration is minimal or does not occur,
ANT. SEGMENT
I
COM. HEPATIC
A
ANT. .PROJECTION
I
B
LAT. PROJECTION
resulting in a high extramural or intramural junction of the common bile and pancreatic ducts with a relatively long shared distal duct. INTRAHEPATIC
DUCTS
Cole stated, “In no region of the body are anomalies so common as in the bile ducts and adjacent blood vessels.“7Since the distribution of the larger intrahepatic ducts is characterized by variability rather than predictability, the unexpected should be anticipated if complications resulting from accidental damageto aberrant ducts are to be avoided.‘* Hayes et al.,14 for example, reported 189 clinically significant variants in 400 consecutive biliary tract operations (47.3%) with singleor multiple aberrant ducts representingmore than one-third of the total. The presentdiscussion will be limited to the more common right lobe variants. Variation in the left hepatic ducts is at least as frequent but is of less significance clinically, since these ducts are usually sufficiently
HATFIELD
162
Fig. 7. Unusually low insertions of the right ferent patientsSeveral calculi are evident in the
posterior anomalous
se
:c
Rent ducts (arrows) into the common ( let in B. T = tube cholangiograms.
distant from the operative site that they are not SO liable to accidental injury at cholecystectomy or common duct exploration. The most common configuration is illustrated in Fig. 5. Generally, the duct of the anterior segment of the right lobe appears to continue the smooth curve of the common hepatic duct and has a more cephalic orientation in the liver. The posterior seg-
Fig. 8. Anomalous ducts (curved arrow) T-tube cholangiogram.
drainage into the
of segmental right cystic duct (straight
hepai :ic arrow I).
hepatic
AND
duct
in two
WISE
dif-
ment duct, whose peripheral branches have a more caudal and lateral distribution, usually negotiates a sharp curve just distal to its origin as it courses around a major branch of the portal vein. Figure 6 demonstrates the most common variants, in which either the duct of the anterior or posterior segment of the right lobe drains into the left rather than the right hepatic duct. A low insertion of the right
ANATOMIC
163
VARIATION
hepatic duct or of a segmental or subsegmental branch into the common hepatic duct is not uncommon (Fig. 7) and is of considerable interest because of its proximity to the triangle of Calot. Eight anomalies of this type were encountered in the 150 biliary tract operations reported by Moody et al. l6 in 1963 (5.3% incidence). Insertion directly into the cystic duct can occur, although it is less common (Fig. 8). So-called subvesical ducts-anomalous branches located in the inferior portion of the right lobe in close proximity to the gallbladder-are found quite frequently in postmortem studies. Healey and Schroy rs noted such a duct in 34.5% of their dissections. “In not a single instance did the subvesical duct have any direct communication with the gallbladder by the so-called hepatocystic ducts. . .” Figure 9 illustrates one such duct. COMMENT
It should be reemphasizedthat unlessthe radiologist and surgeon recognize the many possible variations in biliary anatomy, opportunities for inadvertent surgical injury to the bile ducts will be frequent. A meticulous cholangiographic demonstration of the relevant anatomy should contribute significantly to a reduction in the incidence of avoidable biliary trauma.
Fig. 9. Subvasical the gallbladder but cholangiogram.
duct (arrow) in not communicating
close
proximity to with it. T-tube
ACKNOWLEDGMENT All of the illustrations the Williams & Wilkins
are reproduced Co.12
by permission
of
REFERENCES 1. Anderson RD, Connell TH, Lowman RM: Inversion of the liver and suprahepatic gallbladder associated with eventration of the diaphragm. Radiology 97:87-88,197O 2. Baggenstoss AH: Major duodenal papilla; variations of pathologic interest and lesions of the mucosa. Arch Path01 26:853-868, 1938 3. Bartone NF, Grieco RV: Absent gallbladder and cystic duct. Am J Roentgen01 110:252-255, 1970 4. Blanton DE, Bream CA, Mandel SR: Gallbladder ectopia; a review of anomalies of position. Am J Roentgenol 121: 396-400, 1974 5. Bleich AR, Hamblin DO, Martin D: Left-upper quadrant gallbladder. JAMA 147:849-851.1951 6. Campiche P: A rare abnormality of the bile ducts: the anteduodenal position of the cystic duct. Ann Surg 119:774-776,1944 7. Cole WH: Editorial. Congenital anomalies of the bile ducts and adjacent blood vessels. Surg Gynecol Obstet 87:111-112, 1948 8. Elfving G: Crypts and ducts in the gallbladder wall. Acta Pathol Microbial Stand 49 (Suppl 135):1-45, 1960 9. Elias H, Sherrick JC: Morphology of the Liver. New York, Academic Press, 1969 10. Flint ER: Abnormalities of the right hepatic, cystic,
and gastro-duodenal arteries, and of the bile-ducts. Br J Surg 10:509-519,1923 11. Halpert B: Morphological studies on the gallbladder; “true Luschka ducts” and “the RokitanskyAschoff sinuses” of the human gallbladder. Johns Hopkins Hosp Bull 41:77-103, 1927 12. Hatfield PM, Wise RE: Radiology of the Gallbladder and Bile Ducts. Baltimore, Williams Pr Wilkins, 1976 13. Haughton V, Lewicki AW: Agenesis of the gallbladder. Is preoperative diagnosis possible? Radiology 106:305-306, 1973 14. Hayes MA, Goldenberg IS, Bishop velopmental basis for bile duct anomalies. Obstet 107:447-456,1958
CC: The deSurg Gynecol
15. Healey JE Jr, Schroy PC: Anatomy of the biliary ducts within the human liver; analysis of prevailing pattern of branchings and the major variations of the biliary ducts. Arch Surg 66:599-616, 1953 16. Moody angiography.
FG, Asch T, Glenn Arch Surg 87~475-482,
17. Moosman DA, Coller FA: injury to the bile ducts; study
F: Intrahepatic 1963
chol-
Prevention ot traumatic of structures of cysto-
164
hepatic angle encountered in cholecystectomy and supraduodenal choledochostomy. Am J Surg 82:132-143,1951 18. Nelson PA, Schmitz RL, Perutsea S: Anomalous position of the gallbladder within the falciform ligament. Arch Surg 66:679-681, 1953 19. Robertson HE, Ferguson WJ: Diverticula (Luschka’s crypts) of the gallbladder. Arch Path01 40:312-333,194s 20. Ross RJ, Sachs MD: Triplication of the gallbladder. Am J Roentgen01 104:656-661,1968 21. Schachner A: Anomalies of the gallbladder and bile-passages, with the report of a double gallbladder and a floating gallbladder. Ann Surg 64:419-433, 1916 22. Schwartz A, Birnbaum D: Roentgenologic study of
HATFIELD
AND
WISE
the topography of the choledochoduodenal junction. Am J Roentgen01 87:772-776,1962 23. Schwegler RA Jr, Boyden EA: Development of pars intestinalis of common bile duct in human fetus, with special reference to origin of ampulla of Vater and sphincter of Oddi. I. The involution of the ampulla. Anat Ret 67:441-467, 1937. II. Early development of musculus proprius. Anat Ret 68:17-41, 1937. III. Composition of musculus proprius. Anat Ret 68:193-219,1937 24. Sterling JA: The common channel for bile and pancreatic ducts. Surg Gynecol Obstet 98:420-424, 1954 25. Swartley WB, Weeder SD: Choledochus cyst with a double common bile duct. Ann Surg 101:912-920,1935
M. Hatfield,
M.D., and Robert
S
INCE the anatomy of the gallbladder and bile ducts is quite variable, it is imperative that the radiologist and surgeon be alert to clinically significant deviations from the normal. The fact that we continue to seemany iatrogenic common bile duct strictures and biliary fistulas suggests that this goal, however laudable, has not been achieved. EMBRYOLOGY
The origin of the gallbladder and extrahepatic ducts is separate and distinct from that of the intrahepatic ducts and precedes it by several weeks. At the 2.5~mmstageof embryonic developmerit, a bifid bud forms along the ventral margin of the primitive foregut and proliferates laterally into the adjacent mesenchyme(the septum transversum). The more caudal of thesetwo diverticula initiates formation of the gallbladder and extrahepatic ducts and the more cranial initiates formation of the liver and intrahepatic ducts. By the S-mm stage, the originally hollow gallbladdercommon duct primordium and duodenumbecome solid, but they soon revacuolate. The common bile duct lumen is reestablishedby the 7.5-mm stage, and the gallbladder and duodenal lumens are reestablishedsomewhatlater. Portal and hepatic vein development and hepatocyte and Kupffer cell formation precede development of the intrahepatic bile ducts, the veins achieving the usual adult configuration by the 9.5-mm embryonic stage.By the l&mm stage,the intrahepatic ducts consist only of a blindly ending solid cord of cellsextending from the choledochocystic duct toward the liver hilum. Formation of the intrahepatic ducts apparently occursby induction at the point of contact of this blind-ending ductal anlagewith the liver cells.’ Philip M. Hatfield, M.D.: Radiologist, Lahey Clinic Foundation, Boston, Mass. Robert E. Wise, M.D.: Chairman, Department of Diagnostic Radiology, Lahey Clinic Foundation, and Clinical Professor of Radiology, Boston University School of Medicine, Boston, Mass. Reprint requests should be addressed to Philip M. Hatfield, M.D., Department of Diagnostic Radiology, Lahey Clinic Foundation, 605 Commonwealth Avenue, Boston, Mass. 02215. 0 1976 by Grune & Stratton, Inc. Seminars
in Roenfgenology,
Vol.
Xl,
No.
3 (July),
1976
and Bile Ducts
E. Wise, M.D.
Development of the intrahepatic ducts proceeds along the framework provided by the previously formed branches of the portal vein, which evolve through a complex sequenceof anastomoses and obliterations in the primitive vitelline plexus. Only after the venous system is establishedcan formation of the intrahepatic ducts, which follow the portal system like vines on a trellis, proceed. “While one branch of each vine winds tightly around each riser of the trellis, the main trunk and its first subdivisionsare disposedalong the basal bar of the trellis (which representsthe two trunks of the portal vein) in an entirely irregular and unpredictable manner.“’ This accounts for the marked variation in configuration of the intrahepatic ducts. Despite the opportunity for great variation during ductal development, the end result of this remarkable processis an orderly division of the liver into right and left lobes. The resulting surfacetopography is illustrated in Fig. 1. The right lobe is subdivided into superior and inferior segments, with correspondingsuperiorand inferior segmental ducts, and the left lobe is divided into medial and lateral segments.The quadrate lobe, which at one time was thought to be entirely separate,hasbeen demonstrated to be the medial segmentof the left lobe.15 Only the caudate “lobe” standsapart, receiving branches from both the right and left hepatic ducts. GALLBLADDER
Failure in formation, positioning, or septation of the cholecystic component of the primitive choledochocystic duct may occur. Ironically, agenesis of the gallbladder is of interest primarily because symptomsclosely resemblingthose of cholecystitis may develop even though the gallbladderis absent and the bile ducts appearentirely normal at operation. It is assumedto be impossibleto distinguisha nonvisualized pathologic gallbladder from agenesis preoperatively.3 About two-thirds of the lessthan 200 cases in the literature have been diagnosedat operation and one-third at autopsy. Haughton and Lewicki l3 however, have emphasizedthat rectovaginal !fistula, imperforate anus, and absenceof one or more bones are often associated,and their 757
HATFIELD
158
t-RIGHT
the
Fig. 1. Schematic liver segments
LOBE-
I-
drawing of the as seen anteriorly.
LEFT LOBE&
surface
projections
of
presence may provide, in the future, the opportunity to establish the diagnosis with ultrasound or computerized tomographic scanning, without resorting to operation. If the peritoneal reflection that maintains the gallbladder in close apposition to the undersurface of the right lobe of the liver is lax or incomplete, a mobile or floating gallbladder may result, with intermittent herniation into the lesser sac through the foramen of Winslow (Fig. 2). Other anomalies of position, such as the suprahepatic,’ retrohepatic, and left-sided5 gallbladder, are rare. At least one instance of completely separate double gallbladders, with one in the normal position and one left-sided, has been observed.*’ There is also one published example of a gallbladder in the
WISE
falciform ligament, completely separate from the liver.18 The partially or completely intrahepatic gallbladder is of interest primarily because it greatly complicates cholecystectomy. The diag nosis may be difficult to establish radiographically because unusual gallbladder orientations are not uncommon and the relationship to the liver is often indeterminable. If the diagnosis is suspected, it is readily confirmed by means of a sulfur colloid or a rose bengal scan. Should revacuolization of the primitive gallbladder be incomplete, one or more septa may result. A single transverse septum in the fundus is common (the so-called Phrygian cap deformity) as are transverse septa elsewhere in the gallbladder, but they generally are of no consequence clinically. Longitudinal septa, resulting in a double, or on rare occasion, a triple gallbladder*’ are encountered less frequently. They are not particularly significant, being subject to the same spectrum of diseases as the gallbladder that differentiates normally . In the fetus, communications are present between the gallbladder and the intrahepatic ducts through the so-called cystohepatic ducts. While these are common in the infant and newborn,” they usually regress completely by adulthood. Tiny remnants, which communicate with the intrahepatic ducts but not the gallbladder lumen, are found in l%-15% of adult gallbladders at autopsy. 8911 These so-called Luschka ducts are not demonstrable radiographically and usually cause no problem at cholecystectomy. Larger anomalous intrahepatic ducts that drain into the gallbladder occasionally occur. These may be severed at operation if unrecognized, resulting in persistent postoperative biliary fistula (Fig. 3). Hayes et a1.14 observed such communications in 14.7% of 400 biliary operations, although certainly not all were sufficiently large to produce a postoperative bile leak. CYSTIC
Fig. 2. Mobile gallbladder. Combined upper gastrointastinal examination and oral cholecystogram. The gallbladder has herniated through the foramen of Winslow into the lesser sac, so that it projects between the sacond portion of the duodenum and the gastric antrum.
AND
DUCT
Normally the cystic duct, which measures2.53.5 cm in length, inserts into the right or lateral margin of the commonbile duct at an acute angle, 2.5-3.5 cm distal to the bifurcation of the common hepatic duct. While the external union of the cystic and common bile ducts is relatively near the bifurcation of the common hepatic duct, the actual point of junction of their lumens is usually
ANATOMIC
VARIATION
somewhat more distal, most commonly 1 cm superior to the upper margin of the duodenum. Thus, as much as 4.5 cm of the distal cystic duct is often tightly bound to the common bile duct by dense fibrous tissue, so that it is obligatory that a cystic duct remnant be left at cholecystectomy if injury to the common bile duct is to be avoided.‘* A short (lo-25 mm) parallel course has been observed in 15.2% of 250 cases, and a long (greater than 25 mm) parallel course in 4.4%.” In 14% of Flint’s 200 dissections, the duct junction was located between the upper margin of the duodenum and the ampulla and ;.I 1.5% it was in the distal intramural portion, ie, within the wall of the duodenum. Unusual configurations have been observed, such as a completely separate insertion of the cystic duct into the duodenum, or a duct that first passes anterior to the duodenum before coursing beneath it to insert into the common bile duct .‘j Insertion into the right or lateral margin of the common bile duct is the rule, although exceptions are not uncommon. Anterior junction occurs in approximately 4% of cases and posterior junction in 1.5%-6.8%.10~17 In another 0.5%-l .6% of patients, the cystic duct inserts into the left or medial margin of the common bile duct. A posterior course behind the common bile duct, before insertion, is three times more common than an anterior course.17 EXTRAHEPATIC
DUCTS
The common hepatic duct constitutes that portion of the extrahepatic duct that extends from the duct bifurcation (or the junction of the right and left hepatic ducts) to the junction of the cystic duct; the common bile duct is that portion distal to the cystic duct junction. The total length of the common hepatic and common bile ducts, which averages10.2 cm, is variable, depending on body habitus and the point of insertion into the duodenum.** Usually the ducts negotiate a smoothly arcuate curve from the relatively anterior liver hilum, extending posteriorly and medially behind or just lateral to the duodenal bulb. The portion inferior to the duodenal bulb coursesthrough the head of the pancreasor lies in a groove along its anterior surface before inserting into the duodenum. In most cases(74.2%), the papilla of Vater is located along the posteromedial margin of the midportion of the descendinglimb of the duo-
Fig. 3. Anomalous hepatic duct. (A) Fistulogram. Contrast medium introduced into the postoperative cutaneous tract opacifies a subsegmental right hepatic duct. (6) T-tube cholangiogram on same patient. Opacification of the entire biliary system indicates that the anomalous duct, which drained into the neck of the gallbladder, was severed during cholecystectomy.
denurn.** A more distal insertion, at the junction of the descendingand horizontal portions of the duodenum (17%) or into the horizontal portion (S%), is not uncommon. A high insertion into the duodenal bulb or immediate postbulbar region is decidedly lesscommon. At least one example of a common bile duct emptying into the gastric antrum has been reported in the surgicalliterature.*’ Such an anomaly has never, to the best of our knowledge, been demonstratedradiographically. Unlike the gallbladder and intrahepatic ducts, clinically significant anatomic variation in the
160
HATFIELD
AND
WISE
Fig. 4. Anomalous extrahepatic ducts. (A) Operative cholangiogram. The liver and spleen are normally positioned. Because of intestinal reversal, the common bile duct crosses the midline to insert into the leftsided second portion of the duodenum. (B) Nonjunction of the right (white arrow) and left (paired straight arrows) hepatic ducts in a Mongoloid with duodenal stenosis, demonstrated by GI series. The curved arrows bracket the stenotic segment of the second portion of the duodenum. The large barium collection lateral to the bile ducts is the dilated duodenum proximal to the stenosis.
extrahepatic ducts is uncommon and is usually the result of a generalized congenital aberration rather than an isolated phenomenon confined to the bile ducts. Thus, in the case illustrated in Fig. 4A, the extrahepatic ducts are longer than normal, terminating to the left of the midline because of intestinal reversal in a patient with a normally positioned liver and spleen. In Fig. 4B, an unusually low extrahepatic junction of the right and left hepatic ducts resulted in the absence of a unified common bile duct in a Mongol with duodenal stenosis.
Variation in the configuration of the ampulla of Vater and the point of junction of the pancreatic duct with the common bile duct is frequent and accounts for the difficulty often encountered in selecting the appropriate duct during retrograde peroral cannulation. The embryologic development of these structures is exceedingly complicated.23 To summarize, multiple channels form in the wall of the duodenum at a very early stage. By coalescence of vacuoles, two channels, and then eventually one, usually prevail. The primitive am-
ANATOMIC
VARIATION
161
POST. SEGMENT
Fig. 5. Schematic drawings of the most common configuration of the segmental right and left hepatic ducts in the anterior (A) and left lateral (B) projections. Note the sharp curve of the duct of the posterior segment of the right lobe (arrows).
pullary component initially elongates so that the junction of the primitive hepatic and pancreatic ducts is gradually displaced farther from the lumen of the duodenum. This lateral migration is then reversed. A gradual re-migration back through the duodenal wall toward the lumen occurs in association with the development of the surrounding musculature, which is derived both from the wall of the duodenum and from the ducts themselves. The varying degree of this re-migration accounts for the marked differences in size of the ampulla and the location of the junction of the pancreatic and common bile ducts. In 70% of individuals, the length of the ampulla averages less than one-third (4.4 mm) that of the papilla (14.7 mm).24 In 30%40% of patients, the primitive hepatopancreatic ducts fail to unite so that two separate but immediately adjacent papillary orifices result, and the ampulla is entirely absent.2’24 In 3.4%, widely separated orifices are present in the papilla.* Rarely, re-migration is minimal or does not occur,
ANT. SEGMENT
I
COM. HEPATIC
A
ANT. .PROJECTION
I
B
LAT. PROJECTION
resulting in a high extramural or intramural junction of the common bile and pancreatic ducts with a relatively long shared distal duct. INTRAHEPATIC
DUCTS
Cole stated, “In no region of the body are anomalies so common as in the bile ducts and adjacent blood vessels.“7Since the distribution of the larger intrahepatic ducts is characterized by variability rather than predictability, the unexpected should be anticipated if complications resulting from accidental damageto aberrant ducts are to be avoided.‘* Hayes et al.,14 for example, reported 189 clinically significant variants in 400 consecutive biliary tract operations (47.3%) with singleor multiple aberrant ducts representingmore than one-third of the total. The presentdiscussion will be limited to the more common right lobe variants. Variation in the left hepatic ducts is at least as frequent but is of less significance clinically, since these ducts are usually sufficiently
HATFIELD
162
Fig. 7. Unusually low insertions of the right ferent patientsSeveral calculi are evident in the
posterior anomalous
se
:c
Rent ducts (arrows) into the common ( let in B. T = tube cholangiograms.
distant from the operative site that they are not SO liable to accidental injury at cholecystectomy or common duct exploration. The most common configuration is illustrated in Fig. 5. Generally, the duct of the anterior segment of the right lobe appears to continue the smooth curve of the common hepatic duct and has a more cephalic orientation in the liver. The posterior seg-
Fig. 8. Anomalous ducts (curved arrow) T-tube cholangiogram.
drainage into the
of segmental right cystic duct (straight
hepai :ic arrow I).
hepatic
AND
duct
in two
WISE
dif-
ment duct, whose peripheral branches have a more caudal and lateral distribution, usually negotiates a sharp curve just distal to its origin as it courses around a major branch of the portal vein. Figure 6 demonstrates the most common variants, in which either the duct of the anterior or posterior segment of the right lobe drains into the left rather than the right hepatic duct. A low insertion of the right
ANATOMIC
163
VARIATION
hepatic duct or of a segmental or subsegmental branch into the common hepatic duct is not uncommon (Fig. 7) and is of considerable interest because of its proximity to the triangle of Calot. Eight anomalies of this type were encountered in the 150 biliary tract operations reported by Moody et al. l6 in 1963 (5.3% incidence). Insertion directly into the cystic duct can occur, although it is less common (Fig. 8). So-called subvesical ducts-anomalous branches located in the inferior portion of the right lobe in close proximity to the gallbladder-are found quite frequently in postmortem studies. Healey and Schroy rs noted such a duct in 34.5% of their dissections. “In not a single instance did the subvesical duct have any direct communication with the gallbladder by the so-called hepatocystic ducts. . .” Figure 9 illustrates one such duct. COMMENT
It should be reemphasizedthat unlessthe radiologist and surgeon recognize the many possible variations in biliary anatomy, opportunities for inadvertent surgical injury to the bile ducts will be frequent. A meticulous cholangiographic demonstration of the relevant anatomy should contribute significantly to a reduction in the incidence of avoidable biliary trauma.
Fig. 9. Subvasical the gallbladder but cholangiogram.
duct (arrow) in not communicating
close
proximity to with it. T-tube
ACKNOWLEDGMENT All of the illustrations the Williams & Wilkins
are reproduced Co.12
by permission
of
REFERENCES 1. Anderson RD, Connell TH, Lowman RM: Inversion of the liver and suprahepatic gallbladder associated with eventration of the diaphragm. Radiology 97:87-88,197O 2. Baggenstoss AH: Major duodenal papilla; variations of pathologic interest and lesions of the mucosa. Arch Path01 26:853-868, 1938 3. Bartone NF, Grieco RV: Absent gallbladder and cystic duct. Am J Roentgen01 110:252-255, 1970 4. Blanton DE, Bream CA, Mandel SR: Gallbladder ectopia; a review of anomalies of position. Am J Roentgenol 121: 396-400, 1974 5. Bleich AR, Hamblin DO, Martin D: Left-upper quadrant gallbladder. JAMA 147:849-851.1951 6. Campiche P: A rare abnormality of the bile ducts: the anteduodenal position of the cystic duct. Ann Surg 119:774-776,1944 7. Cole WH: Editorial. Congenital anomalies of the bile ducts and adjacent blood vessels. Surg Gynecol Obstet 87:111-112, 1948 8. Elfving G: Crypts and ducts in the gallbladder wall. Acta Pathol Microbial Stand 49 (Suppl 135):1-45, 1960 9. Elias H, Sherrick JC: Morphology of the Liver. New York, Academic Press, 1969 10. Flint ER: Abnormalities of the right hepatic, cystic,
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CC: The deSurg Gynecol
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FG, Asch T, Glenn Arch Surg 87~475-482,
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F: Intrahepatic 1963
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Prevention ot traumatic of structures of cysto-
164
hepatic angle encountered in cholecystectomy and supraduodenal choledochostomy. Am J Surg 82:132-143,1951 18. Nelson PA, Schmitz RL, Perutsea S: Anomalous position of the gallbladder within the falciform ligament. Arch Surg 66:679-681, 1953 19. Robertson HE, Ferguson WJ: Diverticula (Luschka’s crypts) of the gallbladder. Arch Path01 40:312-333,194s 20. Ross RJ, Sachs MD: Triplication of the gallbladder. Am J Roentgen01 104:656-661,1968 21. Schachner A: Anomalies of the gallbladder and bile-passages, with the report of a double gallbladder and a floating gallbladder. Ann Surg 64:419-433, 1916 22. Schwartz A, Birnbaum D: Roentgenologic study of
HATFIELD
AND
WISE
the topography of the choledochoduodenal junction. Am J Roentgen01 87:772-776,1962 23. Schwegler RA Jr, Boyden EA: Development of pars intestinalis of common bile duct in human fetus, with special reference to origin of ampulla of Vater and sphincter of Oddi. I. The involution of the ampulla. Anat Ret 67:441-467, 1937. II. Early development of musculus proprius. Anat Ret 68:17-41, 1937. III. Composition of musculus proprius. Anat Ret 68:193-219,1937 24. Sterling JA: The common channel for bile and pancreatic ducts. Surg Gynecol Obstet 98:420-424, 1954 25. Swartley WB, Weeder SD: Choledochus cyst with a double common bile duct. Ann Surg 101:912-920,1935
