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 Table of Contents  
Year : 2021  |  Volume : 10  |  Issue : 3  |  Page : 155-159

Morphological variations of the cystic duct and its clinical significance: A cadaveric study

1 Associate Professor, Department of Anatomy, Government Medical College, Pudukkottai, Tamil Nadu, India
2 Professor, Department of Anatomy, Government Medical College, Pudukkottai, Tamil Nadu, India
3 Professor, Department of Anatomy, Thanjavur Medical College, Thanjavur, Tamil Nadu, India

Date of Submission28-May-2021
Date of Decision19-Jun-2021
Date of Acceptance21-Jun-2021
Date of Web Publication30-Jul-2021

Correspondence Address:
Sumathi Shanmugam
Government Medical College, Pudukkottai, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/NJCA.NJCA_69_21

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Background: Anatomical variations of the cystic duct (CD) are common with an incidence of 18%–23% and are commonly encountered during cholecystectomy. The prevalence of such variations in our region is recorded so as to create awareness to avoid significant ductal injury in biliary surgery. Methodology: This observational cross-sectional study was undertaken on one hundred specimens of liver with extrahepatic biliary apparatus available in the department of anatomy. The morphology of CD was studied with respect to its length, course, mode, and level of union. Descriptive statistical analysis was done. Results: The range of length of the CD varied between 0.6 and 5.5 cm. The mean length of the CD was 2.06 ± 1.142 cm. 15% were short CDs and 3% had long CDs. The CD opened into the right hepatic duct in 2% and there was a triple confluence in 1%. There was a high union of CD with common hepatic duct (CHD) in 7.2% and a low union in 3.1%. The CD joined the CHD at an acute angle in 82.47% laterally and medially in 1.03%, paralleled in 11.3% of which 9.3% had a short parallel course, and 2% had a long parallel course and spiralled either anteriorly or posteriorly in 5.2%. Conclusion: These variations of CD have surgical significance in order to avoid damage to the ducts during surgical procedures, especially with increasing laparoscopic cholecystectomies. Hence, an awareness to look for these variations in preoperative radiological imaging is essential for the surgeons to avoid catastrophes.

Keywords: Cystic duct, variations, surgical implications

How to cite this article:
Shanmugam S, Subbiah K, Thiagarajan S. Morphological variations of the cystic duct and its clinical significance: A cadaveric study. Natl J Clin Anat 2021;10:155-9

How to cite this URL:
Shanmugam S, Subbiah K, Thiagarajan S. Morphological variations of the cystic duct and its clinical significance: A cadaveric study. Natl J Clin Anat [serial online] 2021 [cited 2022 Oct 6];10:155-9. Available from: http://www.njca.info/text.asp?2021/10/3/155/322807

  Introduction Top

Extrahepatic biliary duct variations are a well-recognized entity. A basic knowledge of not only the normal anatomy but also of the anatomical variations of extrahepatic biliary ducts is essential for the successful performance of cholecystectomies.[1] Operative injury of these ducts is one of the tragedies of gallbladder surgery and is the cause for 80% of benign strictures and occasionally can even result in mortality.[2] The cystic duct (CD) variations are very common attracting not only surgeons but also anatomists and radiologists with an incidence of 18%–23%.[3] Anatomical variations of CD with regard to its length, level of union with common hepatic duct (CHD), and the pattern of junction of CD with CHD are frequently encountered during routine dissections and imaging.[4] Failure to recognize these variations results in surgical complications and becomes a troubleshooter in endoscopic interventional techniques.[5]

The purpose of our study was to demonstrate the morphological variations in respect of the length, level, and mode of insertion of the CD in the cadavers and to document the prevalence of these CD variations in our population. Short CDs and high union of CDs or union with right hepatic duct (RHD) may cause risks during surgical interventions. Long CDs and low union of CD predisposes to many pathological conditions such as the formation of calculus, ductal obstruction, and occurrence of sclerosing cholangitis.[6] Hence, the findings of this study may create an awareness among the surgeons as the number of surgical procedures for gallbladder diseases are increasing.

  Materials and Methods Top

This observational cross-sectional study was done on 100 specimens of human liver with intact extrahepatic biliary system available from the department of anatomy collected over the years from cadavers and autopsy. Four specimens that were damaged and diseased were excluded from the study. The specimens that were fixed in 10% formalin were numbered serially and dissected with the aim to ascertain the anatomy of the CD with respect to its length, course, the mode, and the level of its insertion into CHD. The study was conducted after obtaining approval from the Institutional Ethical Committee (IEC No: 34/2020 dated June 10, 2020).

The course of the CD was traced from the neck of gallbladder until its insertion. The length of CD was measured using a measuring tape and recorded in metric system. The CDs were classified as short CDs (<1 cm), normal (1–5 cm), and long CDs (>5 cm). The level of union of the CD with the CHD based on its distance from the Porta hepatis to duodenal ampulla was noted. The union of CD with CHD in the upper one third was recorded as high union and lower third as low union, respectively. The mode of union of CD with the CHD was classified based on Eisendrath's classification as angular, parallel, or spiral. The angular union was recorded as lateral or medial insertion depending on the side of union. The parallels were classified as short parallels when the CD and CHD runs together for <2 cm and long parallels when they run together for more than 2 cm. The spiral union was classified as anterior spiral and posterior spiral based on its relation with CHD before its union with CHD. The observations were recorded and photographs were taken. The findings were analyzed using standard descriptive statistical analytical methods. The results are presented as either mean ± standard deviation or as percentages with corresponding graphical representation.

  Results Top

The range of length of the CD was from 0.6 to 5.5 cm. The mean length of the CD was 2.06 ± 1.142 cm. Fifteen specimens had a CD length <1 cm and three specimens had CD measuring more than 5 cm [Table 1] and [Figure 1].
Table 1: Frequency of the length of cystic duct

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Figure 1: (a) Long Cystic duct. (b) Short Cystic duct GB-Gallbladder, 1-Cystic duct, 2-Common hepatic duct. 3-common bile duct

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Regarding the level of insertion of CD into CHD, in two specimens, the CD opened into the RHD (2%), and in one specimen, the RHD, left hepatic duct (LHD), and CD opened as a triple confluence into the common bile duct (CBD) (1%). In 89.7% of the remaining specimens, the level of union of CD with CHD was normal. There was a high union in 7.2% and a low union in 3.1% of specimens [Figure 2]a and [Figure 2]b.
Figure 2: (a) Distribution of the level of union of cystic duct with common hepatic duct. (b) Level of union of Cystic duct with Common hepatic duct. (b1) High union. (b2) Low union. GB-Galbladder, (1) Cystic duct, (2) Common hepatic duct. (3) Common bile duct, *Site of union. (b3) Cystic duct draining into right hepatic duct. (1) Cystic duct (2) common bile duct, Arrow: right hepatic duct

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The CD joined the CHD on the right lateral aspect at an acute angle in 80 specimens and on the medial aspect of the CHD in one specimen (lateral – 82.47% and medial – 1.03%). The CD ran parallel to the CHD before joining it in 11.3%, of which 9.3% had a short parallel course and 2% had a long parallel course. The CD spiralled around the CHD anteriorly to open on its anterior wall in 4.2% and in 1.03% the CD spiralled the CHD posteriorly to open on its medial wall [Figure 3]a and [Figure 3]b.
Figure 3: (a) Distribution of the number of specimens according to the mode of union of cystic duct with common hepatic duct. (b1) Cystic duct draining on medial side of common hepatic duct. (b2) Spiral union of cystic duct with common hepatic duct. (b3) Parallel union of cystic duct with common hepatic duct. GB: Gallbladder, (1) Cystic duct, (2) Common hepatic duct. (3) Common bile duct

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  Discussion Top

The gallbladder is normally situated on the inferior surface of the right lobe of liver in the gallbladder fossa. CD measures 2–4 cm long and continues from the neck of gall bladder to join the CHD on its right lateral aspect usually in the middle third of distance between porta hepatis and duodenal ampulla to form the CBD.[7]

During cholecystectomy, injury to the extrahepatic bile ducts is a serious complication. The length of the CD is significant and it determines the level at which it is inserted into the CHD.[8] The CD length in previous studies ranges from 0.7 to 3.9 cm with a mean 1.9 ± 0.7 cm.[9],[10] In the present study, the range of length of CD was 0.6–5.5 cm which is similar to 0.5–5 cm reported by Ahmed et al.[11] The mean length of CD was 2.60 ± 1.14 cm.

The CD may be extremely short (<1 cm) joining the CHD immediately after leaving the gallbladder or it may be very long (>5 cm) and joins the CHD at a lower level. Short CDs are rare with an incidence of 1.3%–2.6%.[12],[13] In the present study, 15% of short CDs were recorded which is on the higher side similar to 10.8% as has been reported by Ahmed et al.[11] and 20% by Khayat et al.[14] and Lichenstein and Ivy.[15] Many other studies have recorded 1%–3% of short CDs as can be seen in [Table 2]. This frequency of higher percentage of short CDs in the study population can be attributed to its racial predisposition. Short CD if not anticipated may cause tenting of the CHD or CBD when applying traction on the gallbladder, resulting in inadvertent injury to CBD or CHD during clipping or ligation.[8]
Table 2: Comparison of the frequency of short and long cystic ducts by various authors

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Long CDs are widely reported with greater frequency as 13.8%,[11]15%,[14]25%,[15]20%,[16]14%,[17] and 7.5%.[18] In the present study, it was only 3%, and Talpur et al.[12] and Khan et al.[19] have also observed it in only 1% and 1.66%, respectively [Table 2]. A long CD may sometimes run parallel to and be ensheathed in a common fibrous sheath with the CHD. In CD ligation for cholecystectomy, the CHD may be clamped along with CD in such instances resulting in strictures of CHD.[20] No such fibrous sheaths were observed in the present study. Long CD stumps postoperatively in cholecystectomy are frequently associated with associated inflammatory changes and calculous disease.[5]

The CD normally joins the CHD in the middle third of the distance between porta hepatis and duodenal ampulla. The level of insertion of CD accounts for 55% of biliary ductal anomalies.[5] The high union of CD with CHD was 7.2% and low union was 3.1% in the present study. Low medial insertion is significant and literatures report 10%–25%[9] but none was found in our study. Ahmed et al. has reported 7.8% of high union which was similar to the present study and 13.8% of low union which was on a higher side.[11] Pina et al. have reported high percentage of high union (35.48%)[10] and Khayat et al. report 73.3%of high union.[14] In a (magnetic resonance cholangiopancreaticography [MRCP]) study on 198 patients, Sarawagi et al. have documented a prevalence of 5.5% of high union and 9% of low union.[18] Low union of 8%–11% is normal.[21] Low union of CD with CHD predisposes to increased rate of CBD stone formation as well as recurrence of stones. It also produces technical difficulties during (endoscopic retrograde cholangiopancreaticography). MA turner has reported 0.3% high union and 10% of low union.[5] High union of 5.3% and 7% of low union is seen in a MRCP study conducted in 584 cases by F. Roccaselva et al.[20] [Table 3]. The high union of CD with CHD may cause injury to CHD as traction on the CD may produce angulations of the CHD which may be caught within the clamps.
Table 3: Comparison of the level of union of cystic duct with common hepatic duct in various studies

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The CD instead of joining CHD opens into RHD, LHD, or joins the confluence of RHD and LHD, thus leading to an absence of CHD.[1] Drainage of CD into RHD is variously estimated 0.3%,[4] 0.6%–2.3%,[6] 4.6%,[11] 1%.[17] 0.8%,[18] 1.7%,[19] and 0.5%.[20] The CD joined the RHD in 2% in the present study. Triple confluence of CD, RHD, and LHD is also rare and was 1% in the present study. The present study shows similar percentage of occurrence as Dasler.[22] With such variations, RHD may be mistaken for CD in cholecystectomy and divided leading to biliary leak.[1]

Based on Eisendrath's classification, the type of union between CD and CHD may be angular, parallel, or spiral.[23] The CD joins the CHD on its right at an acute angle in 58%–75% of individuals.[5] The CD runs parallel to the CHD for a distance of at least 2 cm before joining it to form CBD, wherein the two ducts may be closely adherent or enclosed in a common fibrous sheath has been reported in 1.2%–25%.[3] 10%–18% of CD have a spiral course with medial insertion.[3],[22] Low medial insertion is seen in 8%–11%.[12],[13] The CD may wind either anteriorly or posteriorly to open either into the anterior wall, posterior wall, or medial wall of CHD. The incidence of parallel union (11.3%) and the angular union (83.5%) in the present study confirms with other literatures. The spiral union of CD presents with varying frequencies in different researches and was less frequent (5.2%) in the present study similar to other cadaveric studies [Table 4]. Spiral insertion has been reported in a higher incidence in MRCP studies when compared to cadaveric studies.
Table 4: Comparison of the mode of union of cystic duct with common hepatic duct in various studies

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The malrotation of the developing CD due to faulty transfer of choledochoduodenal junction during rotation of the duodenum either clockwise or anticlockwise results in the spiral course of CD.[25] Both the parallel and spiral type of union present difficulties during surgery. The findings of the present study were similar to most other studies as can be inferred from [Table 4].

Clinically significant variations of the CD include (i) absent or short CD, (ii) low insertion of CD (9%), (iii) parallel course of CD with CHD for 2 cm or more (1.2%–25%), (iv) anterior or posterior spiral course with medial insertion (10%–17%), (v) drainage of CD into right hepatic or LHD, (vi) accessory intrahepatic ducts draining into CD, and (vii) double CD (2–4%).[9] All these significant variations were observed in this study except for double CDs and intrahepatic ducts draining into CD.

  Conclusion Top

Morphological variations of CD are common and hence have paramount surgical importance. Knowledge of these variants, the short CDs, high union of CD with CHD, anomalous drainage of CD into RHD and as a confluence which are found more in this study is crucial to avoid damage to the CHD or RHD or LHD during surgical procedures. The parallel or spiral union of CD with CHD is likely to result in either postcholecystectomy syndrome or strictures of CHD as a postoperative sequelae. Hence, awareness of these variations and preoperative radiological imaging to look for these variations is essential for the surgeons to recognize and make precise affective approaches.

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Conflicts of interest

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  References Top

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3], [Table 4]


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