Liver segments on ultrasound

This lecture describes the Couinauds liver segments as they appear on ultrasound and how to identify these segments using ultrasonography.

1. Ultrasound of liver segments Dr. Durr-e-Sabih MBBS. MS. FRCP. FANMB Multan Ultrasound Service Distt Jail Road Multan [email protected]

2. The segments 2 3 4 8 5 7 6 1

3. Liver segments The segments are distribution in different planes in the liver volume, with segment 1 being completely posterior and segments 6 and 7 being mostly posterior. The ligaments in the fissures, portal and hepatic vessels are used to locate the segments.

4. Liver segments The ligaments and hepatic veins run at the boundaries between the segments, but the boundaries are not visible all around the segments. The hepatic veins are seen best in the cranial part of the liver, this makes intersegmental distinction in this portion easy, but more inferiorly the divisions become more ill defined.

5. Hepatic veins

6. Liver segments The portal vein branches run to the centre of the segments except the ascending branch of the left portal vein, that runs in the left intersegmental fissure; helping to divide the medial from the lateral part of the left lobe, segment 3 from segment 4.

7. Segment 1 Segment 1 lies between the inferior vena cava; the ligamentum venosum and the left branch of portal vein. It is unique that it can receive branches from both the right as well as left portal veins and has hepatic veins that drain directly into the inferior vena cava. It is quite easy to identify on ultrasound. On a transverse section ,this can have a quadrilateral shape but on a sagittal section, it is more wedge shaped.

8. Segments 1,3,4

9. Segments 1,2,3

10. Segments 2 and 3 These form the lateral part of the left lobe and are located to the left of the umbilical portion of the portal vein, the ligamentum venosum and the falciform ligament. There is some difference about the location of segments 2 and 3 within the left lobe. Some authors place the segments one above the other dividing the segments along an imaginary line extending laterally along the left branch of portal vein.

11. Segments 1,2,3

12. High transverse section

13. Segments 1,3,4

14. Branches of left portal vein

15. Segment 4

16. Segment 4 This is the quadrate lobe and is located on both sides of the horizontal portion of the left portal vein (pars transversa ). Boundaries include the umbilical portion of the left portal vein and the falciform ligament separating it from segments 2 and 3; the ligamentum venosum separates it from segment 1 posteriorly. Laterally the middle hepatic vein and the main hepatic hepatic fissure separates this from the right lobe segments 5 and 8. Segment 4 is itself subdivided into a superiorly located segment 4A and inferiorly located segment 4B by the horizontal segment of the left portal vein (pars transvera ).

17. Segment 4

18. Segments 5-8 Segments 5 - 8 make up the right lobe and are further divided into anterior (5 and 8) and posterior sub-sets (6 and 7). The right hepatic vein forms the boundary between the anterior and posterior subsets, and a line from the right portal vein divides the segments into superior (7 and 8) and inferior (5 and 6) sub-sets. The intersegmental boundaries are not anatomical and this makes right lobe segment identification somewhat difficult.

19. Segment 5 Segment 5 appears on a longitudinal section immediately to the right of the main portal vein, and in some patients can include the part of liver in front of the gallbladder, but since the fundus of the gallbladder can have in inconstant position, this relationship cannot be assumed in every patient.

20. Segment 5

21. Segment 6

22. Segment 5,6,7,8

23. Tip of the right lobe is made up of segment 5 anteriorly and segment 6 posteriorly

24. Left portal vein branches

25. High transverse section

26. Mid transverse section

27. Low transverse section

28. High Mid Low

29. End

30. Left and right portal veins