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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 11  |  Issue : 3  |  Page : 126-130

Clinical relevance of the caudate linguiform process (ponticulus hepatis) in human liver


1 Department of Surgery, Port of Spain General Hospital, Port of Spain, Trinidad and Tobago
2 Section of Anatomy, Department of Basic Medical Sciences, University of the West Indies Mona, Kingston 7, Jamaica

Date of Submission15-May-2022
Date of Decision05-Jun-2022
Date of Acceptance14-Jun-2022
Date of Web Publication12-Aug-2022

Correspondence Address:
Shamir O Cawich
Department of Clinical Surgical Sciences, University of The West Indies, Augustine Campus, St. Augustine
Trinidad and Tobago
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/NJCA.NJCA_94_22

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  Abstract 


Background: The caudate linguiform process (CLP), also known as Ponticulus Hepatis, is loosely defined as a bridge of hepatic parenchyma that overlaps the inferior vena cava (IVC) fossa, occasionally converting it into a canal. The primary objective of this study was to document anatomic variants of the CLP in the human liver. A secondary objective was to perform a systematic literature review of the CLP. Methodology: We analyzed cadaveric livers and selected those with a CLP for detailed examination. Two types of CLPs were defined: A partial CLP that leaves >9 mm of retrohepatic IVC exposed and a complete CLP that leaves <10 mm of IVC surface visible. The following data were recorded: CLP height, CLP width, CLP thickness, relationship to IVC, and width of exposed IVC. Results: A CLP was present in 36 (64%) of 56 cadaveric livers studied. There were 15 (41.7%) complete CLPs and 21 (58.3%) incomplete CLPs. Complete CLPs had a mean height of 54.22 ± 11.20 mm, width of 12.51 ± 3.56 mm, thickness of 7.39 ± 3.93 mm, and left only 6.38 ± 1.75 mm of exposed IVC. The incomplete CLPs had a mean height of 51.36 ± 11.19 mm, width of 11.44 ± 3.25 mm, thickness of 9.49 ± 4.38 mm and left 13.43 ± 3.35 mm of IVC exposed and accessible. Conclusions: We have proposed exact definitions of the CLP using specific anatomic points that are radiologically identifiable, reproducible, and clinically relevant. There is a high prevalence of CLPs in this population, with 42% being complete CLPs. By preventing access to the retrohepatic IVC, a CLP increases the technical complexity of the surgery.

Keywords: Anatomy, caudate, linguiform, liver, ponticulus hepatis, segment


How to cite this article:
Cawich SO, Gardner MT, Louboutin JP, Naraynsingh V. Clinical relevance of the caudate linguiform process (ponticulus hepatis) in human liver. Natl J Clin Anat 2022;11:126-30

How to cite this URL:
Cawich SO, Gardner MT, Louboutin JP, Naraynsingh V. Clinical relevance of the caudate linguiform process (ponticulus hepatis) in human liver. Natl J Clin Anat [serial online] 2022 [cited 2022 Oct 6];11:126-30. Available from: http://www.njca.info/text.asp?2022/11/3/126/353725




  Introduction Top


In classic anatomic descriptions, the inferior vena cava (IVC) sits in a vertical depression on the bare area of the liver that bears its name, and the fossa is not covered with hepatic parenchyma.[1] The linguiform process of the caudate lobe,[1] also known as ponticulus hepatis,[2] is a variant is which a parenchymatous tongue covering IVC fossa, so converting it into a canal. Surgeons must be aware of its variations when dealing with injuries to the retrohepatic vena cava and also during elective major liver resections.

In the Caribbean population, there have been reports of unique variations in liver surface anatomy,[3],[4],[5] hepatic arterial supply,[6],[7] and bile duct anatomy,[8] but there is no data on the caudate linguiform process (CLP) variants in persons of Caribbean descent. There are also no robust definitions of the CLP subtypes in the medical literature. Considering that the volume of hepatic injuries from trauma and hepatobiliary procedures performed in the Caribbean has increased in the past decade,[9],[10],[11] this knowledge is important to optimize service delivery in this setting. The objective of this study was to evaluate the existing variations in the CLP in the Caribbean population. A secondary objective was to perform a systematic review of the CLP in the medical literature.


  Materials and Methods Top


After securing institutional review board approval (ECP 64, 20/21), two independent investigators carried out a prospective, observational study to dissect 56 human livers from prosected specimens at The University of the West Indies in Kingston, Jamaica. Each liver was explanted and the retrohepatic surface of each explanted liver was examined on the dissection bench. We included all consecutive livers in adult cadavers and excluded specimens with gross liver pathology (macronodular cirrhosis, hepatic tumors, trauma).

The gross morphology of the bare area of the liver was observed and classic anatomic descriptions were employed [Figure 1].[12],[13],[14] In classic anatomic descriptions, the IVC sits in a vertical depression on the bare area of the liver that bears its name.[2],[12],[13],[14] This fossa is created by the liver segments VI/VII on the right and the caudate lobe proper on the left. The floor is formed by the caudate process (aka para-caval portion).[14] On its superficial (posterior) surface, the fossa for the IVC is not covered with hepatic parenchyma.
Figure 1: Gross morphology of the bare area of liver explanted on the dissection bench. The IVC can be seen (broken line) flanked on the left by the caudate lobe (S1) on the left and segments 6/7 on the right. The IVC is exposed as it lies in the caudate fossa. The CP separates the IVC and structures in the porta hepatis. CP: Caudate process, IVC: Inferior vena cava

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The CLP (ponticulus hepaticus) is a described anatomic variation in which the fossa for the IVC is covered by parenchyma extending across the retrohepatic IVC.[14],[15],[16],[17] However, an exact definition has not been found in the literature. We define the CLP as the presence of hepatic parenchyma extending across the left caval margin [Figure 2]. The left caval margin was defined by an imaginary line joining the left border of the supra and infra-hepatic IVC at two exact points: Left hepatic vein (LHV) junction and the left portal vein takeoff. These points were chosen because these are points that can be identified clinically and radiologically. Therefore, they will be reproducible and have clinical relevance. Both investigators took measurements of the IVC fossa using electronic calipers (General Tools, MFg Co., New York, USA) and the mean was the figure used in the study.
Figure 2: Drawing demonstrating the definition of the CLP: A CLP is present when the liver parenchyma extends across the left caval margin. The left caval margin was defined by an imaginary line joining the left border of the supra and infra-hepatic IVC at two points: Left hepatic vein and the left branch of portal vein. CLP: Caudate linguiform process, IVC: Inferior vena cava

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Two types of CLPs have been defined:[14] A complete CLP fully covers the retrohepatic IVC [Figure 3] and a partial CLP incompletely covers the IVC fossa, allowing the IVC to be visible without any parenchymal dissection [Figure 4]. However, a robust definition of “incomplete” has not been encountered in the literature. For the purposes of this study, we defined a partial CLP as one that left >9 mm of exposed IVC [Figure 5]. Any specimen with <10 mm of IVC surface visible was considered a complete CLP. This value was chosen because exposure of <1 cm of IVC surface was not thought to be clinically relevant.
Figure 3: Retroperitoneal surface of the liver with a complete CLP fully covering the retrohepatic IVC (surgical forceps lies in the lumen of IVC), creating an intra-hepatic tunnel through which the IVC passes. CLP: Caudate linguiform process, IVC: Inferior vena cava

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Figure 4: Retroperitoneal surface of the liver with a partial CLP leaving a portion of retrohepatic IVC (broken line) exposed. CLP: Caudate linguiform process, IVC: Inferior vena cava

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Figure 5: Diagram demonstrating partial CLP. CLP: Caudate linguiform process, IVC: Inferior vena cava, CP: Caudate process

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The following data were recorded for each CLP: Width (distance across the IVC fossa), height (vertical length), and thickness measured at the middle of the retrohepatic IVC. The CLP was then excised to elucidate relationships and measurements of the retrohepatic IVC. The following dimensions of the IVC were measured: Exposed part (that part not covered by the CLP) and covered part (covered by a parenchymatous bridge). The data were analyzed using SPSS version 20.0 (IBM, Chicago, Illinois, USA) to generate descriptive data.

We then conducted a systematic review of studies from the Cochrane, Pubmed, Medline and Google Scholar databases using the following search terms: “ponticulus hepatis,” “hepatocaval ligament,” “linguiform process,” “caudate lobe” and “IVC canal,” “IVC fossa,” “caudate extension,” “retrohepatic IVC,” “retrohepatic segment of IVC,” “extension of caudate lobe,” “dorsal liver” and “dorsal segment of the liver.” All studies encountered were reviewed by two investigators and the raw data extracted. The following data were extracted: terminology/definitions used, geographic origin of research, size of the study population, CLP prevalence and CLP sub-types. Any disagreement between researchers was resolved in a meeting.


  Results Top


There were 36 cadavers with a CLP. Of all cadavers with CLPs, 15 (41.7%) had complete CLPs and 21 (58.3%) had incomplete CLPs.

The following measurements were recorded in cadavers with complete CLPs: mean CLP height was 54.22 mm (median 56.35 mm, standard deviation [SD] ± 11.20 mm), mean width was 12.51 mm (median 12.09 mm and SD ± 3.56 mm), and mean thickness was 7.39 mm (median 6.81 mm and SD ± 3.93 mm). The mean width of the exposed IVC (that part not covered by the CLP) was 6.38 mm (median 6.59 mm, SD ± 1.75 mm).

In the cadavers with incomplete CLPs, the mean height was 51.36 mm (median 52.64 mm, SD ± 11.19 mm), mean width was 11.44 mm (median 10.18 mm and SD ± 3.25 mm), and mean thickness was 9.49 mm (median 8.03 mm and SD ± 4.38 mm). The mean width of the exposed IVC (that part not covered by the CLP) was 13.43 mm (median 13.33 mm, SD ± 3.35 mm).

In the systematic literature review, ten publications that studied the CLP were encountered[1],[14],[15],[16],[18],[19],[20],[21],[22],[23] and the raw data extracted from these studies are summarized in [Table 1].
Table 1: Metanalysis of studies of the caudate linguiform process

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  Discussion Top


Only 36% of the livers in this Caribbean population demonstrated “classic anatomy” of the fossa for the IVC and 64% of cadavers possessed a CLP. In the literature review, there were few authors that specifically studied the CLP. Each of the 10 studies detailed used different terminologies to describe the CLP. However, the detailed re-examination of published images/descriptions reveals that these authors described the CLP. Data cannot be properly analyzed when there is a wide variety of definitions and descriptions in use. To overcome this CLP should be strictly defined as “the presence of hepatic parenchyma extending across the left-caval margin” and classified as partial or complete as detailed above.

Our population has the highest prevalence of a CLP, which ranged from 4%[1] to 56.7%[18] globally. Ninety-six percent (54) of our cadavers were from the West African diaspora–descendants of the trans-Atlantic slave trade.[24] No other publications studied the African diaspora. The CLP prevalence in our Jamaican' population was greater than the 4% incidence in South Indian populations,[1] 26% in North Indian populations,[14] and 40% in British Caucasians.[14] The closest incidence was 56.7% reported in a study of Parisians.[18]

Only two authors reported detailed descriptions of the CLP when identified.[15],[19] Chang et al.[15] identified a complete CLP in 4 of 60 livers in Chinese cadavers, although they described this as a “retro-hepatic segment of the IVC totally encircled by liver substance.” Chang et al.[15] reported that the mean CLP length was 2.5 cm and mean thickness was 0.5 cm. They did not define an incomplete CLP and therefore no measurements are available for comparison. Camargo et al.[19] also described the complete CLP in 9 of 30 Brazilian cadavers as “retro-hepatic segment of IVC totally encircled by liver substance.” In their report, the mean CLP length was 3.2 cm and the mean thickness was 0.7 cm. Again, no figures are available for comparison for incomplete CLP because they did not define an incomplete CLP. In our population mean CLP length (5.4 cm) was longer than in previous reports,[15],[19] but the mean CLP thickness (7.4 mm) correlated with those reports in the literature.[15],[19] Unfortunately, without standardized definitions, we were unable to compare the measurements for incomplete CLPs in our population.

The majority of cadavers (64%) had a well-defined CLP. This is an important finding because this region has a high level of hepatic injuries from trauma.[25] In these cases, the presence of a CLP will prevent surgeons from readily accessing the retrohepatic IVC to control bleeding and repair injuries from penetrating trauma. Excessive hemorrhage from the uncontrolled retrohepatic IVC translates into increased mortality in these patients.

In addition, a CLP will also render elective major liver resections technically difficult because it prevents access to the retrohepatic IVC during surgery. In the conventional technique for liver resection,[26] the right liver is completely mobilized to expose the retrohepatic IVC. However, a complete or thick CLP will prevent access to the retrohepatic IVC. In these cases, it might be better to use an anterior transection technique (in situ split) described by Ozawa,[27] where the hepatic parenchyma is transected from anteriorly without prior exposure or control of the retrohepatic IVC. This is often combined with the hanging maneuver as described by Belghiti et al.,[28] where a tape is placed anterior to the retrohepatic IVC to suspend the liver. A combination of these operative techniques helps to guide the surgical transection line,[29] controls bleeding from deep parenchymal vessels,[10],[29],[30] reduces the risk of tumor rupture,[31] prevents hematogeneous tumour metastasis[10],[31] and lowers transfusion requirements.[10],[29],[30],[31]

Some hepatobiliary surgeons use these techniques routinely, but most will not dispute that these techniques would be preferred over the conventional approach in the following cases: hepatic tumors involving the diaphragm because the liver may not be adequately mobilized;[10],[28] suspected IVC involvement because there is the risk of iatrogenic IVC injury,[31] tumors close to the hepatocaval junction due to the risk of iatrogenic avulsion of the hepatic veins,[30],[31] large bulky tumors at risk for iatrogenic rupture.[30],[31] We now propose that an additional indication for this technique should be planned major resections in patients with a complete CLP identified on preoperative imaging.

Limitation

We acknowledge that this study was limited by small numbers since we could only dissect 56 cadavers that were available for prosection in our institution. Future studies could incorporate larger numbers of cadavers for dissection.


  Conclusions Top


We have introduced an exact definition of the CLP (the presence of hepatic parenchyma extending across the left caval margin) to clarify the multifarious definitions currently used in the medical literature. This uses a specific anatomic point – the left caval margin –which we have defined using specific anatomic points (an imaginary line joining the left border of the supra and infra-hepatic IVC at two exact points: LHV junction and left portal vein takeoff). These can be accurately identified on imaging and therefore are reproducible. Using standardized definitions, there was a high CLP prevalence (64.3%) in this Jamaican population, with 42% being complete CLPs.

This information is clinically relevant because the CLP can be identified pre-operatively on cross-sectional imaging. When present, a CLP can prevent surgeons from accessing the IVC to control bleeding from traumatic retrohepatic injuries. A CLP also increases the technical complexity of liver resections because it prevents access to the retrohepatic IVC. In these patients, surgeons should consider deviating from the conventional technique for right liver resections, in favor of the anterior transection techniques (in situ split).

Acknowledgment

The authors sincerely thank those who donated their bodies to science so that anatomical research could be performed. Results from such research can potentially increase humankind's overall knowledge that can then improve patient care. Therefore, these donors and their families deserve our highest gratitude.[32]

We would like to acknowledge the contributions of Rachael Williams and Peter Ho who assisted with the dissections. There are no conflicts of interest.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Mamatha Y, Murthy CK, Prakash BA. Study on morphological surface variations in human liver. Int J Health Sci Res 2014;4:97-102.  Back to cited text no. 1
    
2.
Murakami G, Hata F. Human liver caudate lobe and liver segment. Anat Sci Int 2002;77:211-24.  Back to cited text no. 2
    
3.
Gardner MT, Cawich SO, Shetty R, Pearce NW, Naraynsingh V. Hepatic surface grooves in an Afro-Caribbean population: A cadaver study. Ital J Anat Embryol 2015;120:117-26.  Back to cited text no. 3
    
4.
Cawich SO, Gardner MT, Shetty R, Pearce NW, Naraynsingh V. Accessory inferior sulci of the liver in Afro-Caribbean populations. Int J Biomed Sci 2016;12:58-64.  Back to cited text no. 4
    
5.
Cawich SO, Gardner MT, Pearce NW, Shetty R, Naraynsingh V. Association between hepatic surface grooves and diaphragmatic slips. Ital J Anat Embyrol 2017;122:64-661.  Back to cited text no. 5
    
6.
Johnson PB, Cawich SO, Roberts P, Shah S, Gardner MT, Gordon-Strachan G, et al. Variants of hepatic arterial supply in a Caribbean population: A computed tomography based study. Clin Radiol 2013;68:823-7.  Back to cited text no. 6
    
7.
Johnson PB, Cawich SO, Shah S, Gardner MT, Roberts P, Stedman B, et al. Vascular supply to the liver: A report of a rare arterial variant. Case Rep Radiol 2013;2013:969327.  Back to cited text no. 7
    
8.
Sinanan A, Cawich SO, Thornton A, Maharaj P. Study of anatomic variants and congenital anomalies in the biliary tree in a Caribbean population. HPB 2017;19:S82.  Back to cited text no. 8
    
9.
Cawich SO, Thomas DA, Ramjit C, Bhagan R, Naraynsingh V. Complex liver resections for colorectal metastases: Are they safe in the low-volume, resource-poor Caribbean setting? Case Rep Surg 2015;2015:570968.  Back to cited text no. 9
    
10.
Cawich SO, Thomas DA, Ragoonanan V, Ramjit C, Narinesingh D, Naraynsingh V, et al. Modified hanging maneouvre facilitates inferior vena cava resection and reconstruction during extended right hepatectomy. J Molec Clin Oncol 2017;7:687-92.  Back to cited text no. 10
    
11.
Cawich SO, Maharaj R, Naraynsingh V, Pearce N, Francis W, Bonadie KO, et al. Clinical outcomes after major hepatectomy are acceptable in low-volume centers in the Caribbean. World J Hepatol 2019;11:199-207.  Back to cited text no. 11
    
12.
Sibulesky L. Normal liver anatomy. Clin Liver Dis (Hoboken) 2013;2:S1-3.  Back to cited text no. 12
    
13.
Dodds WJ, Erickson SJ, Taylor AJ, Lawson TL, Stewart ET. Caudate lobe of the liver: Anatomy, embryology, and pathology. AJR Am J Roentgenol 1990;154:87-93.  Back to cited text no. 13
    
14.
Sagoo MG, Aland RC, Gosden E. Morphology and morphometry of the caudate lobe of the liver in two populations. Anat Sci Int 2018;93:48-57.  Back to cited text no. 14
    
15.
Chang RW, Shan-Quan S, Yen WW. An applied anatomical study of the ostia venae hepaticae and the retrohepatic segment of the inferior vena cava. J Anat 1989;164:41-7.  Back to cited text no. 15
    
16.
Sagoo MG, Agnihotri G. The retrohepatic segment of inferior vena cava and the ostia venae hepaticae in a Northwest Indian population. Braz J Morphol Sci 2009;26:141-4.  Back to cited text no. 16
    
17.
Sahni D, Jit I, Sodhi L. Gross anatomy of the caudate lobe of the liver. J Anat Soc India 2000;49:123-6.  Back to cited text no. 17
    
18.
Heloury Y, Leborgne J, Rogez JM, Robert R, Barbin JY, Hureau J. The caudate lobe of the liver: Review of clinical anatomy. Surg Radiol Anat 1988;10:83-91.  Back to cited text no. 18
    
19.
Camargo AM, Teixeira GG, Ortale JR. Anatomy of the ostia venae hepaticae and the retrohepatic segment of the inferior vena cava. J Anat 1996;188:59-64.  Back to cited text no. 19
    
20.
Sahni D, Harjeet C, Chawla YK, Indar J. Gross anatomy of the retrohepatic segment of the inferior vena cava in northwest Indians. Indian J Med Res 2006;124:63-70.  Back to cited text no. 20
[PUBMED]  [Full text]  
21.
Morjane A, Dahmane R, Ravnik D, Hribernik M. Anatomy and surgical relevance of the hepatocaval ligament. A study on cadaveric livers. Cells Tissues Organs 2008;187:243-6.  Back to cited text no. 21
    
22.
Sontakke YA, Gladwin V, Chand P. Anatomic variant of liver, gall bladder and inferior vena cava. J Clin Diagn Res 2016;10:AD03-5.  Back to cited text no. 22
    
23.
Jurkovikj D. New variant liver surface morphology according to portal vein segmentation. Int J Appl Pure Sci 2016;2:5-16.  Back to cited text no. 23
    
24.
Akyeampong E. Africans in the diaspora: The diaspora and Africans. Afr Aff 2000;99:183-215.  Back to cited text no. 24
    
25.
Ramdass MJ, Cawich SO, Pooran S, Milne D, Ali E, Naraynsingh V. Declaration of a state of emergency in Trinidad and Tobago: Effect on the trauma admissions at the National Referral Trauma Centre. Prehosp Disaster Med 2015;30:229-32.  Back to cited text no. 25
    
26.
Schwartz SI. Right hepatic lobectomy. Am J Surg 1984;148:668-73.  Back to cited text no. 26
    
27.
Ozawa K. Hepatic function and liver resection. J Gastroenterol Hepatol 1990;5:296-309.  Back to cited text no. 27
    
28.
Belghiti J, Guevara OA, Noun R, Saldinger PF, Kianmanesh R. Liver hanging maneuver: A safe approach to right hepatectomy without liver mobilization. J Am Coll Surg 2001;193:109-11.  Back to cited text no. 28
    
29.
Llado L, Munoz A, Ramos E, Torras J, Fabregat J, Rafecas A. The anterior hanging-approach improves postoperative course after right hepatectomy in patients with colorectal liver metaseases. Results of a prospective study with propensity-score matching comparison. Eur J Surg Oncol 2016;42:176-83.  Back to cited text no. 29
    
30.
Beppu T, Ishiko T, Chikamoto A, Komori H, Masuda T, Hayashi H, et al. Liver hanging maneuver decreases blood loss and operative time in a right-side hepatectomy. Hepatogastroenterology 2012;59:542-5.  Back to cited text no. 30
    
31.
Liu CL, Fan ST, Cheung ST, Lo CM, Ng IO, Wong J. Anterior approach versus conventional approach right hepatic resection for large hepatocellular carcinoma: A prospective randomized controlled study. Ann Surg 2006;244:194-203.  Back to cited text no. 31
    
32.
Iwanaga J, Singh V, Ohtsuka A, Hwang Y, Kim HJ, Moryś J, et al. Acknowledging the use of human cadaveric tissues in research papers: Recommendations from anatomical journal editors. Clin Anat 2021;34:2-4.  Back to cited text no. 32
    


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