Surgery STAT: Performing open surgical liver biopsy

Liver biopsy is indicated for a number of hepatic disorders. While laparoscopic surgery is an excellent means of obtaining biopsy samples because of its reduced surgical morbidity, the instrumentation and training required to perform the procedure can limit its usefulness in general practice. Patients that require liver biopsy can be referred to specialists, especially patients at high risk or when a minimally invasive approach is desired. However, becoming familiar with techniques for open liver biopsy allows the general practitioner to perform this procedure when indicated.

Open surgical liver biopsy has many advantages:

• The surgeon can visually inspect the entire liver, sample focal lesions or areas of interest, and easily control hemorrhage.
• Samples can be collected from multiple liver lobes, increasing the likelihood of reaching a diagnosis.
• The samples collected during open surgical liver biopsy are large enough for histopathologic examination or mineral analysis, which is required for diagnosis of some disease conditions.

Overall, histopathology is more accurate than cytology and is usually considered the gold standard for hepatic evaluation. In a study designed to determine the accuracy of diagnosis between hepatic cytology and histology, the two methods were found to be in agreement in only 15 of 56 canine patients and 21 of 41 feline patients.¹

Guillotine technique

The guillotine technique is performed when attempting to sample the outer margin of a liver lobe.

1. Isolate an easily accessible margin of liver lobe and, using monofilament absorbable suture, place a circumferential ligature around the tissue margin. A surgeon's throw or friction knot is recommended for the initial throw.
2. Pull tightly on the loop of suture, crushing the hepatic parenchyma; both blood vessels and bile ducts will be occluded as the soft tissue is crushed. Then tie the suture with an appropriate number of additional throws to complete the knot (Figure 1).
3. Holding the liver margin in one hand, sharply incise the tissue several millimeters distal to your ligature. Ensure there is adequate space between your suture and the tissue margin so the ligature does not slip off and increase the risk for hemorrhage.
4. Do not handle the biopsy sample with forceps or other surgical instruments, as these can damage the tissue and cause artifacts during histopathologic examination. Handle the tissue as minimally as possible before placing it in formalin.
5. Check the biopsy site for hemorrhage. An absorbable gelatin sponge and gentle pressure can be used to control minor hemorrhage.

Figure 1. Guillotine technique: The suture has been tightened around a peripheral area of the liver (A). After completing the knot and transection distal to the ligature, the site is inspected for evidence of hemorrhage (B).

Punch biopsy technique

The punch biopsy technique is best used when sampling centrally located areas of hepatic parenchyma and focal lesions. Keep in mind when using this method that six to eight portal triads at minimum are recommended for accurate results; this can be achieved using a 6-mm Baker’s biopsy punch.²

1. Isolate a focal lesion or centrally located area for biopsy sampling.
2. Prior to sample collection, prepare a piece of absorbable gelatin sponge roughly the same size of the sample you plan to collect. This will be packed in the site after removal of the sample. Alternatively, use the same biopsy punch to cut a piece of gelatin sponge.
3. Press the biopsy punch against the parenchyma and advance in a rotating clockwise and counterclockwise motion (Figure 2). Ensure that you advance less than half the thickness of the lobe to avoid the large hepatic veins located on the dorsal surface of the liver.
4. Using Metzenbaum scissors, cut the deep margin of the sample from its attachment within the parenchyma.
5. Prepare for some hemorrhaging from the biopsy site after removal of the sample. Insert the previously prepared gelatin sponge into the hole to promote hemostasis.

Figure 2. Punch biopsy technique: A punch biopsy instrument is used to sample a central area of the liver (A). Following tissue removal, a piece of absorbable gelatin sponge is placed in the defect (B) to attain hemostasis.

General considerations

To improve access to the liver, be sure to extend the laparotomy incision to the xiphoid process of the sternum. Sterile laparotomy pads can also be placed gently between the diaphragm and the liver to improve visualization. Using radio-opaque gauze markers and counting the number of surgical sponges prior to closure of the abdomen are essential.

Before closure, it is important to ensure there is no evidence of hemorrhage. While the techniques described here should produce minimal bleeding, there is always a risk for serious complications. Furthermore, patients with significant hepatic dysfunction should always be evaluated for coagulation abnormalities prior to surgery.

Conclusion

Performing open surgical liver biopsy using a guillotine or punch biopsy technique is a valuable skill any general practitioner can learn. The diagnostic information obtained can ultimately improve the level of care provided to patients.

Dr. Steph Shaver is an ACVS board-certified veterinary surgeon and assistant professor of small animal surgery at Midwestern University in Arizona. She enjoys hiking, travel, friends, family and teaching veterinary students.

Marcus Marella is a third-year veterinary student at Midwestern University in Arizona. He has a strong interest in small animal surgery and hopes to complete a surgical residency in the future. In his free time, he enjoys golfing, skiing and spending time with friends and family.

References

1. Wang KY, Panciera DL, Al-Rukibat RK, et al. Accuracy of ultrasound-guided fine-needle aspiration of the liver and cytologic findings in dogs and cats: 97 cases (1990-2000). J Am Vet Med Assoc 2004;224:75-78.
2. Vasanjee SC, Bubenik LJ, Hosgood G, et al. Evaluation of hemorrhage, sample size, and collateral damage for five hepatic biopsy methods in dogs. Vet Surg 2006;35(1):86-93.