Normal Anatomy of Porta Hepatis—A Cadaveric Study

Published online: 28.04.2019

THIEME 22 Original Article

Dhanalaxmi D. Neginhal1 Umesh K. Kulkarni1

1Department of Anatomy, Belagavi Institute of Medical Sciences, Address for correspondence Umesh K. Kulkarni, MS (Anat), Belagavi, Karnataka, India Department of Anatomy, Belagavi Institute of Medical Sciences, Belagavi, Karnataka, India (e-mail: [email protected]).

Natl J Clin Anat 2019;8:22–26

Abstract Background and Aim Porta hepatis (PH) of the liver acts as a gateway for exit and entry of important structures like portal vein, hepatic artery, and hepatic duct. Having knowledge of variations about the dimensions and structures at PH becomes important to avoid complications during surgical and radiological interventions. Our study aims to observe the dimensions of PH and also the number, arrangement, and variations of structures passing through PH. Materials and Methods Fifty adult cadaveric human livers which were preserved in formalin were studied. Transverse diameter, anteroposterior diameter, and circumference of PH were measured using vernier calipers, measuring scale, and thread. PH was carefully dissected to study the number, arrangement, and combination of arteries, veins, and ducts at PH. Results The mean transverse diameter, anteroposterior diameter, and total circumference of PH was 3.17 ± 0.50, 1.68 ± 0.36, and 10.46 ± 1.415 cm, respectively. Eighteen specimens showed presence of two arteries, two veins, and one duct at PH. Keywords Maximum number of arteries, veins, and ducts passing through PH were 5, 4, and 1,

►►porta hepatis respectively. The ducts were anterior, arteries in the middle, and veins were posterior ►►portal vein in PH of all the livers. ►►hepatic artery Conclusion The variations observed in our study will be of great importance to ►►hepatic duct anatomists, surgeons, and radiologists.

Introduction procedures like liver transplant, surgical interventions, and diagnostic radiological procedures which can be associated The liver is the largest gland and the most important organ in with complications. The “complex anatomic architecture” human body. It also performs an astonishingly large number of the vascular and biliary structures at the PH makes it a of tasks that impact the whole body system. As the liver is surgically challenging area.1 Hence, a surgeon requires involved in majority of the metabolic activities in the body, it is detailed knowledge of the normal anatomy of PH and more likely to get affected by various pathological conditions. structures related to it. Porta hepatis (PH) is a transverse nonperitoneal fissure The present study aims in studying the dimensions, on the inferior surface which acts as a gateway of the liver. numerical variations, and arrangement of structures in It extends from the neck of the gall bladder to the fissure for PH. These findings will be of significance for anatomists, ligamentum teres and venosum, and intervenes between the surgeons operating on this region, and radiologists to avoid quadrate lobe in the front and caudate process at the back. iatrogenic complications. Although PH is nonperitoneal, its margins give attachment to lesser omentum. Hepatic artery with autonomic plexus around Materials and Methods it and the portal vein (PV) enter the liver through PH. Lympha- tics and the hepatic duct emerges out of the liver through PH. The study was conducted at the Belagavi Institute of Medical PH transmits important neurovascular structures and Sciences, Belgaum, on 50 adult cadaveric human livers hence it acquires great importance while carrying out clinical preserved in formalin of unknown sex. Ethical approval was

DOI https://doi.org/ ©2019 Society of Clinical 10.1055/s-0039-1688545 Anatomists ISSN 2277-4025. eISSN 2321-2780. Normal Anatomy of Porta Hepatis Neginhal, Kulkarni 23 taken from the institutional ethical committee prior to the transverse diameter and anteroposterior diameter were commencement of the study. 3.17 ± 0.50 and 1.68 ± 0.36 cm, respectively. The mini- Specimens with any surface anomalies and pathologies mum total circumference measured was 7.5 cm and the were excluded from the study. On inferior surface PH was maximum was 12.8 cm with a mean ± SD of 10.46 ± 1.415 identified and the transverse diameter and anteroposterior cm. The measurements are shown in ►Table 1. diameter were measured using sliding vernier calipers. Total ►Table 2 shows various combinations of the structures circumference was measured with a thread and confirmed passing through PH and their frequency of occurrence. with a measuring scale (see ►Fig. 1). Average of three The common combination in our study was two veins, measurements was recorded. The PH was carefully dissected and studied for number, arrangement, and combination of structures (►Figs. 2–6).

Results

In the present study, the transverse diameter and anteroposterior diameter of PH ranged from 2.4 to 4.5 cm to 1.0 to 2.6 cm. The mean ± standard deviation (SD) for

Fig. 3 Porta hepatis with four veins.

Fig. 1 Line diagram of the inferior surface of liver with porta hepatis showing the various diameters measured. Abbreviations: AP, anteroposterior diameter; C, circumference represented by dotted line; CL, caudate lobe; GB, gallbladder; IVC, inferior vena cava; LL, left lobe, Fig. 4 Porta hepatis with five arteries, two veins, and one duct. QL, quadrate lobe; RL, right lobe; TD, transverse diameter.

Fig. 2 Porta hepatis with two arteries, two veins, and one duct. Fig. 5 Porta hepatis with three arteries, two veins, and one duct.

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Discussion

PH acts as the gateway of liver through which important structures entry and exit, namely, the PV, hepatic artery, and hepatic duct. The anatomical arrangement and dimensions of these structures is very important for surgeons and radiologists. Common complications of surgeries around the liver may be vascular or nonvascular like biliary peritonitis or biliary stricture following bile duct injury, vascular complications like pseudoaneurysms, hematoma, arterial dissections, or transections. Some of the minimal invasive procedures like percutaneous drainage catheter placement, Fig. 6 Porta hepatis with four arteries, one vein, and one duct. balloon dilatation, stenting, and coil embolization also lead Abbreviations: A, artery; D, duct; HA, hepatic artery; PV, portal vein; V, vein. to complications.2 In this study, 50 formalin preserved livers were studied two arteries, and one duct which were seen in 36% of for the dimensions of PH which included the transverse and specimen followed by two veins, three arteries, and one anteroposterior diameters and the circumference which duct in 22% and one vein, two arteries, and one duct in 20% showed a wide variation. The number of structures and their of specimens. arrangement with various combinations was observed, the most The number of structures varied from one to five for common combination observed was of two veins, two arteries, arteries; 56% of specimens showed two arteries and one to and one duct which were seen in 36% of specimens (►Fig. 2). four veins,72% of specimens showed two veins, and 100% As shown in ►Table 4, our findings correlates with other of specimens showed only one duct (►Figs. 2–6). Details studies.3,4 PV showed bifurcation in 72% of specimen which was for the number of structures passing through PH and their highest followed by single vein in 26% and maximum number frequency of their occurrence are shown in ►Table 3. of veins was four which was seen in 2% of specimen (►Fig. 2). The arrangement of structures in the PH was constant. Trifurcation of vein was not observed in the present study. The ducts were anterior, arteries in the middle, and veins As a result of advances in noninvasive cross-sectional were posterior in PH of all the livers. imaging techniques and improvements in multidetector

computed tomography, three-dimensional imaging has become possible, due to which the abdominal venous Table 1 Dimensions of porta hepatis anatomic variations and anomalies are commonly detected 5 Dimensions Range Mean and standard in routine examinations. Anatomical variations of the PV (cm) deviation (cm) are common, and extensive study has been conducted to understand the varying branching patterns of the PV and Transverse diameter of 2.4–4.5 3.17 ± 0.50 few studies have also reported about the absence of PV the porta hepatis branching.6–8 Anteroposterior diameter 1.0–2.6 1.68 ± 0.36 Advancements in surgical and interventional procedures of the porta hepatis of the liver increase the significance of PV variations. Total circumference 7.5–12.8 10.46 ± 1.415 Anatomic PV variations play a critical role in evaluations before surgical interventions, transplantations, and interventional procedure of the liver.9 Table 2 Various combinations of structures passing through porta hepatis and their frequency of occurrence Table 3 Number of each structures passing through porta Combination Number of specimen % of hepatis and frequency of their occurrence (n = 50) specimen Number of Number of specimen % of specimen 1V2A1D 10 20 structures (n = 50) 2V3A1D 11 22 1 artery 04 08 1V4A1D 01 02 2 arteries 28 56 2V1A1D 02 04 3 arteries 13 26 2V2A1D 18 36 4 arteries 04 08 2V4A1D 04 08 5 arteries 01 02 1V3A1D 01 02 1 vein 13 26 2V5A1D 01 02 2 veins 36 72 1V1A1D 01 02 4 veins 01 02 4V2A1D 01 02 1 duct 50 100 Abbreviations: A, artery; D, duct; V, vein.

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Table 4 Comparison of observations of the present study with figures quoted in similar studies Observations Present study Sapna et al3 Gupta et al4 Number of specimens 50 59 25 Transverse diameter of the porta hepatis 2.4–4.5 cm 2.5–8 cm 2.4–6 cm Anteroposterior diameter of porta hepatis 1.0–2.6 cm 1.25–3 cm 1.2–2.6 cm Total circumference 7.5–12.8 cm – 10.2–18 cm Most common combination 2A 2V 1D (36%) 2A 1V 1D (25.4%) 2A 1V 1D (32%) Max no. of arteries 05 04 05 Max no. of veins 04 03 03 Max no. of ducts 01 03 03 Abbreviations: A, artery; D, duct; V, vein.

Hepatic artery proper is a branch of the common hepatic Conclusion artery, it passes through the right free margin of the lesser omentum and enters the PH where it divides into right and The findings in this study will help anatomists, radiologists, left branch. Number of arteries found in PH in the present and surgeons to understand the variations of dimensions, study was from one to five; two arteries were seen in 56% of number, and arrangement of structures at PH. specimen and three arteries in 26%. Five arteries were seen Conflict of Interest in 2% of the liver (►Fig. 4). Common variations reported None. about the hepatic artery is about its branching pattern and its accessory arteries.10–12 A study has also reported about the anomalous variation of the origin of the right and left References hepatic artery.13 1 Tirumani SH, Shanbhogue AK, Vikram R, Prasad SR, A surgeon should have immense knowledge about Menias CO. Imaging of the porta hepatis: spectrum of disease. the variants of the hepatic artery to reduce iatrogenic Radiographics 2014;34(1):73–92 2 Covey AM, Brody LA, Getrajdman GI, Sofocleous CT, Brown KT. complications in hepatobiliary surgeries, surgical manage-

Incidence, patterns, and clinical relevance of variant portal ment of liver trauma, aneurysm of hepatic artery, hepatic vein anatomy. AJR Am J Roentgenol 2004;183(4):1055–1064 arterial infusion chemotherapy, liver transplant surgery, and 3 Sapna M, Shetty SD, Nayak S. A study on the number other such surgeries of this complex anatomic region.14 and arrangement of the structures passing through the In the present study, single hepatic duct was observed porta hepatis in South Indian population. Int J Morphol 2015;33(1):164–168 in all the livers, and hepatic duct showed no branching 4 Gupta D, Sharma P, Gandotra A. Porta hepatis in normal liver. (►Figs. 2–6). As mentioned in Gray’s text book of anatomy, IJBAR 2017;8(3):121–125 the main right and left hepatic ducts unite near the right 5 Calhoun PS, Kuszyk BS, Heath DG, Carley JC, Fishman EK. end of PH as the common hepatic duct and passes down- Three-dimensional volume rendering of spiral CT data: theory wards within the right free margin of the lesser omentum.15 and method. Radiographics 1999;19(3):745–764 However, in our study, we have not observed the right and left 6 Koç Z, Oğuzkurt L, Ulusan S. Portal vein variations: clinical implications and frequencies in routine abdominal extrahepatic part of the hepatic duct. Our finding correlates multidetector CT. Diagn Interv Radiol 2007;13(2):75–80 with similar observations, single duct was observed in 79.7 7 Kouadio EK, Bessayah A, Valette PJ, et al. Anatomic variation: 3,4 and 76% of liver specimens, respectively. Anatomical and absence of portal vein bifurcation. Surg Radiol Anat radiological studies have shown the presence of accessory 2011;33(5):459–463 hepatic ducts at different levels of the biliary tree and also 8 Chaib E. Absence of bifurcation of the portal vein. Surg Radiol observed the absence of right and left hepatic ducts.16–19 Anat 2009;31(5):389–392 9 Erbay N, Raptopoulos V, Pomfret EA, Kamel IR, Kruskal JB. Because of these anatomic variations, it becomes very much Living donor liver transplantation in adults: vascular variants important to have knowledge about these hepatic duct important in surgical planning for donors and recipients. AJR variations of accessory hepatic ducts and also about their Am J Roentgenol 2003;181(1):109–114 position, especially during laparoscopic cholecystectomies, 10 Kamath BK. A study of variant hepatic arterial anatomy as incidence of bile duct injuries is as twice as high when and its relevance in current surgical practice. Int J Anat Res. compared with open cholecystectomies.20 2015;3(1):947–953 11 Pujahari AK. Problem of a rare anomalous hepatic artery during Biliary anatomy and its common and uncommon variations Whipple procedure. Saudi J Gastroenterol 2010;16(2):122–123 are of considerable clinical significance when performing 12 Covey AM, Brody LA, Maluccio MA, Getrajdman GI, living donor transplantations, radiological interventions in Brown KT. Variant hepatic arterial anatomy revisited: digital hepatobiliary system, laparoscopic cholecystectomy, and subtraction angiography performed in 600 patients. Radiology liver resection (hepatectomy, segmentectomy). Magnetic 2002;224(2):542–547 13 Bhardwaj N. Anomalous origins of hepatic artery and its resonance choliangiopancreatography has become the significance for hepatobiliary surgery. J Anat Soc India modality of choice for noninvasive evaluation of abnormalities 2010;59(2):173–176 of the biliary tract.

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