Surgeon's Corner: Visceral Biopsy Technique

Liver

Liver biopsy can be accomplished by several techniques.

• To obtain a liver biopsy specimen near the edge of a liver lobe or from a convenient pedunculated mass, a guillotine technique can be used. Using synthetic absorbable monofilament suture material, tie the suture in a guillotine-fashion, leaving the ends long so they can be used as a marker to avoid inadvertent amputation of the vessel-holding ligature.  Mild hemorrhage is normal, but covering the edge of the biopsy site with omentum can assist in hemostasis.

• For specimens that are not located at a convenient marginated area of the liver, a modified guillotine technique can be performed. Drive a needle and suture directly through the midpoint of the proposed biopsy site and create a stay suture. Drive another piece of suture through the exact same hole (or close to it), making another stay suture and bringing it to the opposite side of the proposed biopsy site. A scalpel blade can be used to make asmall incision in the liver capsule to guide the sutures as they are tightened. This guarantees that the suture cuts in the exact desired location, allowing for adequate specimen sampling. Leaving the ends of the Guillotine sutures long helps prevent accidental cutting of the suture material ligating hepatic vessels.  If there is hemorrhage, gentle pressure to encourage coagulation can be helpful.

• Livers with a prominent amount of fibrous connective tissue can be biopsied using the modified technique described above with an exception:  a blunt mosquito hemostat can be used to drive through the parenchyma in the area of the proposed biopsy site to grasp a loop of suture to pull through the liver. (Correction: The audio incorrectly states a loop of “intestine” should be pulled through the liver. It should state a “loop of suture”.) The loop is cut (creating 2 stay sutures) and then tied using a guillotine technique similar to what was previously described. 

• Occasionally, the surface lesion is close enough to the hilus such that guillotine amputation is inconvenient.  A keyhole punch biopsy technique is ideal in such situations.  The keyhole punch biopsy is placed into area of the lesion and twisted back and forth until it cuts the piece of liver, followed by removal of the small tissue biopsy specimen.  Pressure is applied (or gel foam is placed) inside the interior of the biopsy area to facilitate hemostasis. This biopsy method can be used to obtain multiple specimens from specific areas of the liver; the trade-off is that specimen sizes are very small.

Pancreas

Pancreatic biopsy is generally performed by isolating the left limb of the pancreas.

• To isolate the left limb of the pancreas, open the two leaves of the omentum, breaking into the omental bursa and moving towards the epiploic foramen. The left limb of the pancreas does not share its blood supply with any other structure in the area, which makes it convenient to biopsy. A pair of iris or Metzenbaum scissors may be used to remove a wedge of pancreas. Hemostasis in a cat is minimal but can be performed on any surface bleeders by using electrocautery.

• Dogs tend to have a more generous blood supply to their pancreas than cats. In many instances, a guillotine technique is recommended to encourage and guarantee hemostasis. The guillotine technique is performed exactly as described for liver biopsy. The suture ends should be left long so the blade can be guided to ensure an accurate cut to remove the pancreatic segment and leave ligated vessels in place. Pancreatitis secondary to pancreatic biopsy is extremely rare.

Intestine

• A skin punch biopsy instrument can be used to obtain an intestinal biopsy; in a medium-to-large breed dog, a 4-5 mm skin punch is ideal. The anti-mesenteric border of the proposed site is exposed to ensure that the biopsy incision does not extend through the opposite side of intestine. In most cases, a small tag of intestinal mucosa will persist and will require amputation using Metzenbaum scissors. Closure of the biopsy defect should be performed transversely thus avoiding compromise of the lumen diameter of the intestine. Simple interrupted or simple continuous sutures may be used for this closure.

• In an alternate skin punch biopsy method, the intestine is laid on its side; the punch biopsy is driven against a firm surface, such as a towel or sterile tongue depressor, until the blade has completely amputated the specimen. The specimen is then evacuated from the core of the skin punch biopsy instrument; closure of the defect is performed using a simple continuous or simple interrupted appositional suture pattern. This technique is very useful to avoid cutting the anti-mesenteric vessel when performing a biopsy of the ileum.

This video was authored by Howard B Seim III, DVM, DACVS. Other surgical videos are available through VideoVet.

Surgeon’s Corner is intended as a forum for those with specialized expertise to share their approaches to various techniques and procedures. As such, the content reflects one expert’s approach and is not subject to peer review.