Page 139 - Clinical Manual of Small Animal Endosurgery

Diagnostic Laparoscopy 127

which has to be shifted away in a caudal direction with a blunt probe.
To visualise the right kidney it is also necessary to push the duodenum
away. The presence of perirenal fat often hinders kidney visualisation in
obese patients. The normal kidney is a pale purple colour, smooth and
oval-shaped, with evident blood vessels.
The preferred way to obtain renal specimens is with the use of a
®
Trucut biopsy needle. Although this technique does not strictly require
any instrument port, since the biopsy needle is inserted percutaneously,
it is preferable to have one instrument port available for insertion of a
palpation probe to provide haemostasis at the biopsy site. The probe is
positioned near the kidney, and the location for needle insertion is deter-
mined. Palpation of the abdominal wall over the caudal border of the
kidney is observed through the endoscope, thus avoiding the diaphragm,
and allowing sampling of the renal poles. A 2 mm skin incision is per-
formed at the entry site, and a 15 cm 14- or 16-gauge automated Trucut
or similar biopsy needle is introduced under direct visualisation into the
abdomen caudal to the diaphragm. The needle is inserted at a shallow
angle to the capsule, directed away from the hilus, to avoid the corti-
comedullary junction, where the large arcuate vessels are located. Inser-
tion of the needle parallel to the long axis of the kidney may prove
difficult due to the angle of insertion of the needle through the body wall.
The needle can alternatively be inserted at the poles, perpendicular to
the long axis of the kidney. In particular, biopsy samples are more easily
obtained from the cranial pole of the kidney, which is larger than the
caudal pole. In any case, the aim is to obtain mostly the renal cortex
with little medulla, to maximise the number of glomeruli recovered
(Rawlings and Howerth, 2004) (Fig. 4.21). The surgeon must provide a

Fig. 4.21 Line drawing of a core needle biopsy of the kidney illustrating
the correct possible paths of the needle to avoid entering the medulla.