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Journal of the Anatomical Society of India

Ramification Pattern Of Portal Vein In Right Lobe of Liver - A Corrosion Cast Study

Author(s): Arora. J; Kapur. V; Kakkar. A; Dixit. P. C.

Vol. 52, No. 1 (2003-01 - 2003-12)

Department of Anatomy, Maulana Azad Medical College, N. Delhi. INDIA

Abstract

The present study describes the intrahepatic ramification of portal vein in the right lobe of human liver. Corrosion castmodels of human liver were used to conduct this study. The course of portal vein was traced from the porta hepatis to the various segmentsof the right lobe of liver. The anterior and posterior divisions of right branch of portal vein exhibited various patterns of ramification ofsegmental and sub-segmental branches. In 80% of the liver specimens, th anterior division of right branch of portal vein ramified at an acuteangle to the posterior division. In 20% of liver specimens the anterior division was oriented at 90° to the posterior division, a new findingreported in the present study. In 60% of liver specimens the posterior division of right branch of portal vein coursed as a continuous trunk toramify in segments VII & VI of right lobe of liver. The posterior division of right branch of portal vein displayed bifurcation in 20% specimensand trifurcation in another 20% specimens. The study highlights the relevance of the ramification pattern of the right branch of portal vein inhepatic surgery.

Key words: Portal vein, Ramification, anterior division, posterior division, Liver

Introduction:

Knowledge of the segmentation of liver based on intra-hepatic ramification of portal vein (PV) is of value in the localization of pathological processes and in planning surgical approach. Though several workers (Hjortso 1951; Elias & Petty, 1952; Healey & Schroy, 1953; Goldsmith & Woodburne, 1957) have conducted research on the anatomical division of liver, the segmental division of the liver proposed by Couinaud (1957) is the one universally accepted. According to Couinaud (1957) the right lobe of liver is divided into anterior & posterior segments. Each segment is further divided into four sub-segments : the antero-inferior (S5), antero-superior (S8), postero-inferior (S6) and postero-superior (S7). The caudate lobe is an independent segment (S1). (Fig. 1.)

In Couinaud's division of the liver neither detailed description of the boundaries between sub- segments nor the variations in the ramification pattern of the right branch of portal vein (RPV) have been given.

Most of the studies conducted by earlier workers are by dissection method. The present study by corrosion cast method, adds further data to the already existing concepts pertaining to the ramification pattern of PV in the right lobe of liver.

Material and Methods:

Fifteen fresh adult liver specimens without signs of liver disease or trauma were obtained for conducting this study. Each liver specimen was thoroughly washed. The portal vein was exposed by fine dissection. It was further cannulated and ligated. A homogenous solution of cellulose acetate butyrate was injected to prepare corrosion cast models of the liver specimens. The casts thus prepared were studied and distribution patterns of PV in the different segments of the right lobe of liver were recorded.

Observations and Results:

The observations recorded in the present study are based on the segmental anatomy of liver as described by Couinaud. (1957) At the porta hepatis, the PV divided in the conventional manner into a right branch and a left branch in all specimens. Length of the right branch of portal vein (RPV) ranged between 1.3 to 2.3 cms. The angle formed between RPV and the main trunk of PV ranged from 110° to 170°.

The RPV in its course, divided into an anterior division (AD) for the anterior segment and posterior division (PD) for the posterior segment of the right lobe of liver.

Anterior division of RPV: The AD of RPV exhibited two types of distribution patterns:

In 12 out of 15 specimens (80%) the AD ramified at an acute angle to the PD to course further as a gentle medial curve. Branches were given off at various points from this curve to segments S8 (antero-superior) and S5 (antero-inferior) of the anterior segment of right lobe of liver. In the remaining specimens, the AD ramified at right angles to the PD and divided into branches for segments S8 & S5 respectively (Fig. 2). The AD of RPV further divided into antero-superior & antero-inferior branches as it ramified in segment S8 & S5 of right lobe of liver.

Antero-superior branch of AD of RPV: In 9 out of 15 specimens (60%) the antero-superior branch ramified as a single trunk in segment S8. However in the remaining specimens, it further bifurcated into anterior and posterior branches and ramified in segment S8 of the right lobe of liver.

Posterior division of RPV:

The posterior division of RPV displayed three types of distribution patterns as it ramified in segments S6 (postero-inferior) and S7 (postero- superior) of posterior segment of right lobe of liver.

Type I: In 9 out of 15 specimens (60%), the PD of RPV coursed upwards and backwards as a continuous trunk. The PD of RPV gave an inferior branch to segment S6 and then divided into superior and inferior branches for segments S7 and S6 respectively. The superior and inferior branches to these segments fanned out in a parallel fashion from the main posterior division of RPV. (Fig. 3)

Type-II: In 3 out of 15 specimens (20%) the PD showed trifurcation into postero-superior, postero-inferior and intermediate branches. The intermediate branch was well defined and coursed in a transverse direction. This branch occupied the segmental border of segments S6 and S7. The intermediate branch further divided into superior and inferior branches for segments S7 and S6 respectively. (Fig.4)

Type III: In 3 out of 15 specimens (20%), the PD showed bifurcation and simply divided into 2 divisions to ramify in segments S6 and S7 of right lobe of liver.

Discussion:

The present study describes the ramification patterns of PV in the right lobe of liver by using corrosion cast specimens. The study is of clinical importance since thorough knowledge of ramification patterns of the PV is fundamental in the field of hepatic surgery.

The length of RPV ranged from 1.3 to 2.3 cms. A comparison of observations by earlier workers is illustrated in table 1.

Table - 1 Comparison of Length of RPV as observed by earlier workers.

Authors (Year) Length of RPV (Cms)
1. Gupta et al (1977) 0.5-2.0
2. Ralph (1989) 0.5-1.0
3. Mishra. et al (1998) 1.0-2.6
4. Present Study (2003) 1.3-2.3

The RPV divided into anterior and posterior division in all cases. Our work is in accordance with the observations of Healey (1954). The anterior and posterior divisions of RPV showed division into superior and inferior branches for the corresponding hepatic segments. This is in agreement with the work of earlier research workers (Segall, 1923; Kune, 1969; Marks et al, 1979; Van Leewen et al, 1995).

In 80% of specimens the AD of RPV ramified at an acute angle to the PD. However, an angle of 90° was observed in rest of the 20% specimens. To the best of our knowledge, no such finding has been reported till date in literature. In the antero-superior segment S8, the ramification was more frequently seen from a single trunk (60%). Tripoidal type of ramification of the anterior-superior branch was not found in our study as reported by Yamane et al (1998) and Ortale et al (2000). The branch to anteroinferior segment was from the main AD in 80% cases, which is higher as compared to 57% reported by Ortale et al (2000).

The type I pattern was the most common pattern of ramification of PD (60%). This is in accordance with the observation of Couinaud (1957). The type II pattern was observed in 20% specimens. Our observation differed from Yamane et al (1988) who recorded an incidence of 12%. The intermediate branch from the trifurcation site of PD was a significant branch in most cases and exhibited numerous branches to segments S6 & S7. The intermediate branch finds a new emphasis in our study as it supplies additional branches to these segments.

Major postero-inferior branches (1-2) from the PD of RPV were observed in 60% specimens. This is in accordance with the observation made by, Couinaud (1957) and Makuchi. (1986). The posteroinferior branch to segment S6 serves as a guideline for identification of the segmental border between segments S6 & S7.

Our study highlights the importance of the ramification pattern of intrahapatic PV in the right lobe of liver, which might be important for surgeons, radiologists and anatomists. It attempts to contribute towards establishing a definite nomenclature of universal consensus of the ramifying branches of PV. Even for relatively small hepatocellular carcinoma, minimal operative procedures of hepatectomy (partial or subsegmental resection of the liver) are required to preserve maximum residual functions. Further more, since hepatocellular carcinoma is often accompanied by intra portal tumour thrombi, it is important to remove systematically the region including the tumour thrombi in the portal vein, (Yamane et al, 1988).

The present study offers a detailed description of the distribution of PV in the right lobe of liver, which could be of great use in planning such surgical procedures, which lay emphasis upon segmental borders between segments of liver. It is recommended that resection of any portion of the liver should not be performed on the basis of any common pattern of ramification of PV. It should be well planned and the sub-segments should be clearly identified pre-operatively. It is essential for the present day surgeon to be aware of the anatomical basis of intra-hepatic portal venous system to ensure safe hepatic surgery.

References:

  1. Couinaud, C : Le Foie, Eludes anatomiques et Chirugicales, Mason, Paris. (1957)
  2. Elias, H. and Petty, D. (1952) : Gross anatomy of the blood vessels and ducts within the human liver. American Journal of Anatomy. 90 : 59-111.
  3. Goldsmith, N.A. and Woodburne, R.T. (1957) : Surgical anatomy pertaining to liver resection. Surgery, Gynaecology and Obstetrics. 195 : 310-318.
  4. Gupta, S.C. Gupta, C.D. and Arora, A.K. (1977) : Subsegmentation of the human liver. Journal of Anatomy 24 2 : 413-423.
  5. Healey, J.E. Jr. (1954) : Clinical anatomic aspects of radical hepatic surgery. Journal of the International College of Surgeons. 22, No. 5 : 542-550.
  6. Healey, J.E., Jr. and Schroy, P.C. (1953) : Anatomy of the biliary ducts within the human liver. Analysis of the prevailing pattern of branching and the major variations of the biliary ducts. Archives of Surgery. 66 : 599-616.
  7. Hjortso, C.H. (1951) : The topography of the intra-hepatic duct systems. Acta Anatomica 11 : 599-615.
  8. Kune, G.A. (1969) : The Anatomical basis of liver surgery. Australian New Zealand Journal of Surgery. 39 : 117-126.
  9. Makuuchi, M : (1986) : Study of the ramification of the right posterior portal vein by ultrasonography. Kan-zou. 27 : 526.
  10. Marks W.M. et al (1979) : Ultrasonic anatomy of the liver : a review with new applications. Journal of Clinical Ultrasound. 7 : 137-146.
  11. Mishra, S; Rehokhieya, Ajmani, M.L., Murty; O.P. (1998) : The segmental anatomy of human liver by special technique of vascular injection. Journal of Forensic Medicine and Toxicology. 25 (2): 5-9.
  12. Ortale, J. R. Cristiano, Humberto; Naves de Freitas; Azevedo Clesio; Mello de Castro (2000). Anatomy of the intra-hepatic ramification of the portal vein in the right hemiliver. Cells, Tissues, Organs, 166 : 378-387.
  13. Ralph, G. (1989) : Surgical anatomy of the liver. Surgical Clinics of North America. 69 : 179-192.
  14. Segall, H.N. (1923) : An experimental investigation of the blood and bile channels of the liver. Surgery, Gynaecology and Obstetrics 37 : 152 - 175.
  15. Van leewen, S.M. Noordzij, J. Fernandez, A.N.: Hennipman, A; Feldberg; A.M.; Dillon, H.E. (1994) : Portal venous and segmental anatomy of the right hemiliver; observations based on three dimensional spiral CT renderings. American Journal of Roentgenology. 163 : 1395-1404.
  16. Yamane, T; Mori, K; Sakamoto, K; Ikey, S; Akagi, M. (1988) : Intrahepatic ramification of the portal vein in the right and caudate lobes of the liver. Acta Anatomica. 133 : 162-172.

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Fig.1

Diagrammatic illustration showing the hepatic segments based on the distribution of portal vein (Couinaud)

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Fig.2

Corrosion Cast preparation of the liver (antero-superior view) displaying intrahepatic ramification pattern of portal vein (angle between AD & PD is 90) 1-LPV, 2, 3, 4, 5-bb of LPV 6-br. of AD of RPV, 7-AS br. of AD of RPV, 8-Al br. of AD of RPV, 9-RHV, 10-MHV, 11-LHV, 12-PD of RPV.

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Fig-3

Corrosion Cast preparation of the liver (postero-inferior view) displaying intra-hepatic ramification patten of PD of RPV as a single trunk.

1-RPV, 2-PD of RPV, 3-PS bb of PD of RPV, 4 - PI br of PD of RPV, 5 - inferior bb, of PD of RPV, 6, 7, 8, 9 - bb of LPV 10 - IVC, 11 - RHV, 12 - LHV.

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Fig.4

Corrosion cast preparation of the liver (postero-inferior view) displaying trifurcation pattern of ramification of PD of RPV.

1-PT, 2 - RPV , 3 - LPV, 4 - PD of RPV, 5-PS br. of PD of RPV; 6-Lateral br. of PD of RPV; 7-PI br of PD of RPV, 8, 9, 10, - bb of LPV.

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