Harbin's index: Morphological evaluation of caudate-to-right lobe ratio in human cadaveric liver

Jaikumar B Contractor; Vipul D Patel; VH Vaniya

doi:10.4103/jasi.jasi_25_21

ORIGINAL ARTICLE

Year : 2021 | Volume : 70 | Issue : 3 | Page : 168-172

Harbin's index: Morphological evaluation of caudate-to-right lobe ratio in human cadaveric liver

Jaikumar B Contractor¹, Vipul D Patel², VH Vaniya³
¹ Assistant Professor, Department of Anatomy, Pramukhswami Medical College, Bhaikaka University, Karamsad, Gujarat, India
² Associate Professor, Department of Anatomy, Government Medical College, Surat, Gujarat, India
³ Professor, Department of Anatomy, Baroda Medical College, Vadodara, Gujarat, India

Date of Submission	12-Feb-2021
Date of Acceptance	11-Aug-2021
Date of Web Publication	23-Sep-2021

Correspondence Address:
Dr. Jaikumar B Contractor
B-7, Rushi Tenaments, Behind Munjal Park, Samta, Vadodara - 390 023, Gujarat
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jasi.jasi_25_21

Abstract

Introduction: Liver cirrhosis is essentially an end stage liver fibrosis that develops as a continuation of normal wound healing in response to chronic liver injury. While 1/4th of cirrhotic livers are morphologically normal in size and configuration, on computerized tomography, over 1/3rd are diffusely atrophic and almost 50% manifest focal hypertrophy most commonly in the caudate lobe concomitant with segmental atrophy of the right lobe. Aims and Objectives: To analyze the morphometric measurements of the right lobe and determine the C/RL in human cadaveric liver and compare the values of C/RL ratio to previously documented studies in an attempt to provide baseline data. Material and Methods: The study was conducted on 100 human cadaveric livers at Anatomy Department, Medical College Baroda, Vadodara, Gujarat. Morphometric measurements were observed in mm with threads and digital Vernier Caliper. Results: The transverse diameter of the right lobe averaged 78.22 ± 12.17 mm, with values ranging at 55.06–98.30 mm. The longitudinal diameter of the right lobe averaged 126.31 ± 20.24 with values ranging at 90.54–172.18 mm. Harbin's Index was calculated as the ratio of the CT to right lobe, i.e., (CT/RT), and averaged 0.38 ± 0.12 with values ranging at 0.17–0.61. Discussion and Conclusion: While nodular regeneration within liver parenchyma may be difficult to recognize on ultrasonography and any irregularity of the liver surface may be apparent only with macro nodules or ascitic effusion, caudate lobe hypertrophy is a consistent finding with liver cirrhosis or other chronic liver disease.

Keywords: Caudate to right lobe ratio, Harbin's index, liver cirrhosis

How to cite this article:
Contractor JB, Patel VD, Vaniya V H. Harbin's index: Morphological evaluation of caudate-to-right lobe ratio in human cadaveric liver. J Anat Soc India 2021;70:168-72

How to cite this URL:
Contractor JB, Patel VD, Vaniya V H. Harbin's index: Morphological evaluation of caudate-to-right lobe ratio in human cadaveric liver. J Anat Soc India [serial online] 2021 [cited 2021 Dec 3];70:168-72. Available from: https://www.jasi.org.in/text.asp?2021/70/3/168/326427

Introduction

Globally, hepatitis is considered one of the most common causes of chronic liver disease and continues to affect a large fraction of the population. Overall, 1/5^th of the acute hepatitis C cases proceed to cirrhosis and coupled with ascites, encephalopathy, and altered liver function tests, such cases, invariably warrant liver transplantation.^[1] Hence, it becomes imperative to have thorough knowledge of the liver anatomy and its variations to achieve successful surgical outcomes, especially in the era of diagnostic imaging and minimally invasive surgeries.^[2]

Liver cirrhosis is essentially an end-stage liver fibrosis that develops as a continuation of normal wound healing in response to chronic liver injury. Histologically, it presents as hepatocyte islands in the form of regenerative nodules that are devoid of central vein and are surrounded by fibrotic septa. Functionally, the exchange between hepatic sinusoids and adjacent parenchyma is compromised through shunting of portal and arterial blood directly into the hepatic outflow. Impaired liver function, portal hypertension, hepatocellular carcinoma are few well-known sequelae of liver cirrhosis.^[3]

Currently, liver biopsy is the choice of investigation for diagnosing liver cirrhosis.^[4] However, sampling errors in needle biopsies, incomplete interpretation of semi-quantitative scores, intricacies in recognizing a fully developed stage of cirrhosis in needle biopsy specimens raise substantial challenges.^[5] On the other hand, while 1/4^th of end-stage cirrhotic livers are morphologically normal in size and configuration, on computerized tomography, over 1/3^rd are diffusely atrophic and almost 50% manifest focal hypertrophy most commonly in the caudate lobe concomitant with segmental atrophy of the right lobe.^[6]

Anatomically, caudate lobe is identified on the liver as a prominence on its inferior and posterior surfaces. Situated posterior to porta hepatis it is related with the fissure for ligamentum venosum on the left and groove for inferior vena cava on its right. Based on the distribution of portal venous branches and the location of hepatic veins in the parenchyma, functionally, it acts as a separate lobe and corresponds to segment I of the eight functional segments of the Couinaud's division of liver.^[7]

Caudate lobe to right lobe ratio (C/RL) is one such morphological measurement used to record the hepatic changes in cirrhotic livers. Globally accepted values of C/RL ratio range to <0.6, values between 0.6 and 0.65 are considered borderline, and any value >0.65 can indicate a case of liver cirrhosis.^[8] The purpose of this study is to analyze the morphometric measurements of the right lobe and determine the C/RL in human cadaveric liver and compare the values of C/RL ratio to previously documented studies in an attempt to provide baseline data.

Material and Methods

This descriptive observational study was carried out on 100 Human cadaveric livers available at the Anatomy Department, Medical College Baroda, Vadodara, Gujarat. Details of the study were submitted and approved according to the ethical and legal standards of the Institutional Ethics Committee for Human Research, Medical College and SSG Hospital, Baroda (EC Reg. No.: ECR/85/Inst/GJ/2013/RR-16, Dated: November 02, 2017). Cadavers, embalmed with formalin-based embalming fluid were dissected during anatomy practical classes to remove the liver en bloc along with hepatic segment of inferior vena cava and the structures present in the porta hepatis. Demographic information was not collected as a part of this study. Nineteen specimens with gross appearance of any pathological conditions were excluded from the study. Each liver was held in an anatomical position to identify its visceral and parietal surfaces and morphometric measurements were calculated in mm with the help of cotton threads and Kristeel digital Vernier Caliper with calibration certificate 200 mm/8 inch (2917).

Three lines, L1, L2, and L3 were marked with the help of cotton threads at the following locations:

L1: Through the right lateral wall of the main portal vein
L2: Parallel to L1 at the most medial margin of the caudate lobe
L3: Perpendicular to lines L1 and L2, midway between main portal vein and the inferior vena cava, and extended out to the lateral margin of the right lobe.

The distance along line 3, between lines 1 and 2, was the transverse diameter of the caudate lobe (CT). The distance along line 3, between the lateral margin of the right lobe and line 1, was the transverse diameter of the right lobe (RT)^[9] [Figure 1].

Figure 1: The first line (L1) through the right lateral wall of the main portal vein. A second line (L2) is marked parallel to L1 at the most medial margin of the caudate lobe. A third line (L3) is marked perpendicular to the first two lines, midway between the main portal vein and the inferior vena cava extended out to the most lateral margin of the right lobe

Click here to view

C_T: Measured from the most medial margin of the caudate lobe to the right lateral wall of the portal vein^[8]
R_T: Measured from the right lateral wall of the portal vein to the most lateral margin of the right lobe^[8]
Longitudinal diameter of Caudate lobe (C_L): Measured as the maximum longitudinal extension of the caudate lobe from the inferior border of the caudate lobe just above the porta hepatis^[9]
Longitudinal diameter of Right lobe (R_L): Vertical length was measured by taking mid-point of the RT as the reference.^[10]

Harbin's index (C_T/R_T) was calculated as the ratio of CT to the RT.

All hepatic measurements were taken by the principal investigator on three different occasions and the average of the readings was considered for computation. The findings were documented, photographed and data were analyzed using descriptive statistics and Shapiro–Wilk test to study any deviation.

Results

Morphometric analysis of caudate lobe

The values of transverse diameter (28.69 ± 7.73 mm) and longitudinal diameter (54.97 ± 10.73 mm) of caudate lobe have been discussed in another paper by the same author.^[11]

Morphometric analysis of right lobe

The RT was averaged 78.22 ± 12.17 mm with values ranging at 55.06–98.30 mm and median value of 79.84 mm. The R_L was averaged 126.31 ± 20.24 mm with values ranging at 90.54–172.18 mm and median value of 126.54 mm. Shapiro-wilk test was used to revealed normal distribution, for both, Transverse diameter of Right lobe (RT) and Longitudinal diameter of Right lobe (RL). The P values calculated were 0.001 and 0.02 respectively [Figure 2].

Figure 2: Transverse diameter of the right lobe measured on L3 between L1 and most lateral margin of right lobe

Click here to view

Harbin's index

Harbin's Index was measured for each specimen by taking ratio of the C_T to R_T, and accordingly, the average value for Harbin's Index is derived to be 0.38 ± 0.12 with values ranging at 0.17–0.61 and median value of 0.36. Shapiro–Wilk test reveal that Harbin's Index was not normally distributed as P = 0.001.

Discussion

Morphology of caudate lobe

Morphometric measurements of caudate lobe in the present study were observed, as discussed in another paper by the same author.^[11] While literature does not narrate the relationship between caudate lobe and interior of the liver sufficiently. This was addressed in the hypothesis proposed by Dodds et al.^[12] which states that during the second trimester, as the liver enlarges, the liver (developing within the ventral mesentery) and the mesentery of the ductus venosus rotate towards right around and behind the mesentery of ductus venosus resulting in a small portion of the liver being wedged behind the mesentery of ductus venosus, within an angle formed by ductus venosus and the inferior vena cava. It clarifies that the caudate lobe develops from a small portion of both the hepatic lobes, and subsequently, vascular supply comes from both right and left hepatic arteries and both portal veins. Furthermore, small communicating veins pass directly between the caudate lobe and inferior vena cava. Becker et al.^[13] state that since emissary veins that open directly into the inferior vena cava maintain the venous drainage of caudate lobe, any obstruction of hepatic vein causes increased blood flow through caudate lobe resulting in hypertrophy often accompanied with right or left lobar atrophy, primarily seen in cirrhosis.

Morphology of right lobe

Using the method given by Harbin et al. (1980), we measured the average RT as 78.22 ± 12.17 mm and the average R_L as 129.65 ± 37.73 mm. Similar findings with the average RT as 88.3 ± 13.2 mm (range 70–119 mm) in males and 81.8 ± 12.3 mm (range 69–98 mm) in females and have been presented by Sahni et al.^[14] in their study on autopsied liver specimens preserved in 10% formalin at Postgraduate Institute of Medical Education and Research, Chandigarh. In a radiographic study on adult healthy volunteers at College of Medical Sciences University of Maiduguri, Bomo, Ahidjo et al.^[15] measured the mean ± standard deviation for the RT as 88.7 ± 12.6 mm (range 62–110 mm) in males and 83.6 ± 10.4 mm (range 62–108 mm) in females. Chavan and Wabale^[16] studied 50 embalmed livers at RMC, Loni, and measured the average RT as 84 mm (range 67–105 mm). In another study on embalmed livers at Shri Ram Murti Smarak Institute of Medical Sciences, Bareilly, Arora et al.^[10] measured the average RT as 77.9 mm (range 52.9–99.3 mm) and longitudinal diameter (vertical length) of the right lobe as 114.3 mm (range 95.2–136.3 mm). Sagoo et al.^[9] in a similar study on embalmed livers in two different populations, North-West Indian (NWI) and the United Kingdom Caucasian also derived the average RT to 80.6 ± 10.16 mm and 88.2 ± 10.9 mm, respectively.

Harbin's index

Harbin's index calculated as the ratio of CT to RT in the present study valued 0.38 ± 0.12. Harbin's index values for other studies are described in [Table 1].

Table 1: Harbin's index values

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While nodular regeneration within liver parenchyma may be difficult to recognize on ultrasonography and any irregularity of the liver surface may be apparent only with macro-nodules or ascitic effusion,^[17] caudate lobe hypertrophy is a consistent finding with liver cirrhosis or other chronic liver disease.^[18] Hence, any pathological changes in the caudate or right lobe of liver could be determined through knowing the normal morphometric measurements in healthy adult subjects. Following are the comparative values of Harbin's index in control groups and known cases of cirrhosis [Table 2].

Table 2: Comparison Harbin's index in known cirrhosis and control group

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To begin with, Harbin et al.^[8] calculated the hepatic indices on in situ liver specimens through ultrasonography. While it was possible to identify the same points on livers dissected from cadavers embalmed with formalin, it would be interesting to consider if ultrasonographic measurements in living patient can be applied to embalmed tissue without modification. Rutherford and Karanjia^[22] studied <10% shrinkage in freshly resected liver specimens placed in 10% formalin solution for 24 h and stated that although the liver parenchyma does shrink the magnitude of the effect is considerably small. Similarly, Nlebedum et al.^[23] in their study on the effect of embalming fluids on histological appearance of organs from embalmed West African goat cadavers found that while microscopic architecture of liver tissue from embalmed cadavers appear moderately distorted, the morphology of hepatocytes and Kupffer cells remain normal. More so, the central vein, portal triad, covering capsule and vasculature, especially the sinusoids, also remain normal. This quality preservation seen in cadaveric liver samples may be attributed to profuse vascularity of the liver, since embalming fluids were administered through vessels.

Conclusion

The present study confirms the values of caudate to right lobe ratio in normal subjects, and there is a significant difference in the values when compared with known cases of liver cirrhosis. Based on these findings, it can be concluded that caudate to right lobe ratio (Harbin's index) can be highly reliable parameter for diagnosing liver cirrhosis and other chronic liver disease.

Acknowledgments

We would like to acknowledge the donors from Medical College Baroda, Vadodara, who provided the material for the study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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