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Russolillo et al. Mini-invasive Surg 2023;7:3 https://dx.doi.org/10.20517/2574-1225.2022.74 Page 3 of 6

4. Correct the direction, i.e., where to start the resection and the correct angle of incidence, which might be
challenging to identify at the beginning. Using ultrasound, the surgeon can adjust the direction to keep
away from the nodule, locate the pedicle at the appropriate section point, and preserve the uninvolved
parenchyma.

The following section will describe the aid provided by IOUS during ARs and non-ARs.

Ultrasound-guided anatomical minor resections
ARs are challenging because of the shortage of clear dissection planes between various hepatic segments.
Intersegmental/sectional borders are determined by (I) hepatic veins, (II) Glissonian pedicles,
and (III) ischemic demarcation routes.

To execute an AR, transection planes are easily recognized by the surgeon using IOUS. Here we report an
example of an S8 segmentectomy.

● The longitudinal plane runs along one or more hepatic veins. The first plane follows the right hepatic
vein, and the second follows the middle hepatic vein (the lateral and medial parts of the line transection,
respectively). Using IOUS with a probe sliding movement on the Glissonian sheet, there are longitudinal
and transversal views. In this way, hepatic veins are easily identified.

● The transverse plane runs from the origin of the tributary portal stalks. In the case mentioned above, this
plane runs along the anterior portal branch between the pedicles of segment 8 (to be ligated) and segment 5
(to be spared).

Surgeons who perform AR connect the longitudinal and transverse planes. IOUS helps verify and correct
the resection plane immediately during the parenchymal transection phase. Once the tributary Glissonian
pedicle is reached, it can be isolated and ligated.

[9]
The primary difference between the ventral and Glissonian pedicle-first approach is the point of stalks
reached during parenchymal transection (advanced and early phase, respectively). Thanks to intraoperative
laparoscopic ultrasound (LUS), relevant portal peduncles are identified for anatomical segmentectomies and
subsegmentectomies of segments 7 and 6 and Sg6-7 bisegmentectomies from the dorsal side of the liver
after completion. Mini-hepatotomy is performed, and the right pedicle is identified, dissected, and clamped.

The final highlight for AR is the ischemic zone on the Glissonian surface. Using intraoperative ultrasound
(LUS or IOUS), selective ligation or clamping of portal pedicles can be easily performed with the ventral or
the Glissonian pedicle-first approach to highlight the ischemic area. We note that parenchymal resection
could also be facilitated using the indocyanine green fluorescence technique because indocyanine injection
makes ischemia evident even deep in the parenchyma while primarily clamping on the surface.

Ultrasound-guided non-anatomical resections
IOUS/LUS guidance is pivotal for the non-anatomical resection of Glissonian pedicles and the hepatic veins
surgical approach.

● LUS/IOUS allows Glissonian pedicle detection at the proper point of ligation. During dissection, to check
these structures, IOUS/LUS prevents iatrogenic injuries of tributaries to disease-free liver parenchyma and
reduces the risk of hemorrhage.