Page 132 - Clinical Manual of Small Animal Endosurgery

120 Clinical Manual of Small Animal Endosurgery

either with a long needle (such as a 20-gauge 5 cm spinal needle) placed
percutaneously, or using a 5 mm laparoscopic needle tipped cannula
through a standard operating port. In some instances, due to the increased
viscosity of the abnormal bile, aspiration can prove difficult. The bile
collected is submitted for cytology and aerobic and anaerobic culture.
To prevent leakage after the procedure as much bile as possible is aspi-
rated. Biliary centesis is not recommended if biliary obstruction is present
because of the increased risk of leakage from the puncture site. Although
aspirates can be taken directly through puncture of the exposed surface
of the gall bladder, some surgeons prefer to place the needle across liver
parenchyma into the gall bladder to reduce the risk of leakage.
Different techniques can be used to obtain liver biopsies. The pre-
ferred method is to use 5 mm laparoscopic cup biopsy forceps; this allows
harvest of relatively large samples from the edge or the surface of the
lobes with minimal tissue trauma and bleeding (Barnes et al., 2006;
Vasanjee et al., 2006). Some biopsy forceps are also equipped with elec-
trocoagulation capability. However, retrieval of biopsy samples using
electrocoagulation is best avoided, as it may cause thermal injury to the
sample. The areas to be biopsied are selected depending on the disease
present: in case of focal lesions, biopsy samples have to be obtained not
only from the affected areas, but also from areas with normal appear-
ance. Areas of necrosis or areas characterised by increased vascularity
and/or distended bile ducts are best avoided. Several samples are taken
(usually five or six unless excessive bleeding occurs), from different liver
lobes, and submitted for histopathology and aerobic and anaerobic
culture. The large size of the samples obtained with 5 mm cup biopsy
forceps (Fig. 4.12) allows acquisition of deep tissue, thus minimising the
risk of non-representative biopsies when sampling areas close to the liver
edge. Increased fibrous tissue is in fact present in subcapsular areas, and

Fig. 4.12 Typical size of laparoscopic liver biopsies.