Inferior Hepatic Fissures: Anatomic Variants in Trinidad and Tobago

Abstract

Classic descriptions of the visceral surface of the human liver only define three fissures: transverse, sagittal and umbilical fissures. Any additional fissures that are present on the visceral surface of the liver are considered variant inferior hepatic fissures (IHFs). This study was carried out to document the prevalence of IHFs in the Eastern Caribbean. Knowledge of these variants is important to clinicians who treat liver disorders in persons of the Caribbean diaspora. In this study, two independent researchers observed all consecutive autopsies performed at the facility over a period of 10 weeks. They examined the visceral surface of the unfixed liver in situ. Any specimen with variant IHFs was selected for detailed study. We documented the relation of the variant IHFs to nearby viscera and then explanted the livers using a standardized technique. The following details were recorded for each liver: number, location, depth, length, and width of IHFs. All measurements were checked independently by two researchers and the average measurement was used as the final dimension. Each liver was then sectioned in 1 cm sagittal slices to document the relationship of intraparenchymal structures. We observed 60 consecutive autopsies in unselected cadavers. Variant IHFs were present in 21 (35%) cadavers at a mean age of 68.25 years (range: 61 - 83; median 64.5; standard deviation (SD) ± 8.45). The variants included a deep fissure in the coronal plane between segments V and VI in 19 (31.7%) cadavers (related to the right branch of the portal vein in 63.2% of cases), a well-defined segment VI fissure running in a sagittal plane in four (6.7%) cadavers, a well-defined fissure incompletely separating the caudate process from the caudate lobe proper in five (8.3%) cadavers, a consistent fissure that arose from the left side of the transverse fissure and coursed between segments II and III in three (5%) cadavers, and a deep coronal fissure dividing the quadrate to form an accessory quadrate lobe in one (1.7%) cadaver. Almost one in three unselected persons in this population have anatomically variant fissures on the visceral surface of the liver. The variants include Rouvière's sulci (31.7%), caudate notches (8.3%), segment VI fissures (6.7%), left medial segment fissures (5%), and quadrate fissures (1.7%). The clinical relevance of these variants is discussed. Any clinician treating liver diseases in persons of Caribbean extract should be aware of their presence.

Keywords: anatomy; caribbean; fissure; hepatic; liver; trinidad; variant.

Figure 1. A view of the visceral surface of an explanted cadaveric liver illustrating classic anatomy

The visceral surface is divided into four areas, roughly in a pattern resembling the letter “H”. The transverse fissure (solid line) forms the central stem of the “H” and runs in a coronal plane, separating the caudate (S1) and quadrate (S4) lobes. At the left end of the transverse fissure, the sagittal fissure (SF) and umbilical fissure (UF) course in opposite directions to separate the left medial (S4) and left lateral (S2 and 3) sections. The oblique fissure (OF) runs from the right side of the transverse fissure toward the inferior vena cava (IVC). An imaginary line connecting the middle of the gallbladder (GB) fossa and the oblique fissure separates the left and right hemiliver.

Figure 2. Fissure between segments 5 and 6

Multiple variants are visible on the visceral surface of this liver. There is an open-type Rouvière’s sulcus (broken line) separating segments 5 (S5) and 6 (S6). The right branch of the portal vein (arrow) is visible at the floor of the fissure covered by a thin layer of Glisson’s capsule. There is also a caudate notch (C) present that incompletely divides the caudate lobe in the sagittal plane. A third fissure (solid line) extends from the left side of the transverse fissure and continues into the left lateral section to separate segments 2 (S2) and 3 (S3).

Figure 3. Segment 6 fissure

This specimen demonstrates an open-type Rouvière’s sulcus (R) separating segments 5 (S5) and 6 (S6). There is also a well-developed fissure in segment 6 roughly oriented in a sagittal plane (arrow), as well as a bilobed gallbladder (GB). The caudate lobe (S1) is labeled for orientation.

Figure 4. Fissure between segments 2 and 3

Visceral surface of a liver demonstrating a well-defined fissure (arrow) that extends from the left end of the transverse fissure and courses into the left lateral section to separate segment 2 (S2) and segment 3 (S3). The caudate (S1) and quadrate (S4b) lobes are labeled for orientation.

Figure 5. Quadrate lobe fissure

Multiple variant fissures are present on the visceral surface of this liver, including an open-type Rouvière’s sulcus (R), a caudate notch (C), and a fissure in the quadrate lobe (arrow) that runs in a coronal plane to create an accessory lobe.