Chief Professional Relations Officer Hill’s Pet Nutrition, Hill’s Pet Nutrition, GPVA, Topeka, KS, USA
Common Endoscopic Oncologic Procedures
Many laparoscopic procedures have been described in human surgery and are performed on a regular basis. Small animal laparoscopy is slowly developing and is often stuck in an experimental phase. However, several veterinary institutions have advocated laparoscopic surgery in the last decade and now few private practitioners and surgical specialists are using this innovative technique instead of the old-fashioned laparotomy.
The procedure of an abdominal exploratory is relatively easy and minimally invasive. A thorough superficial evaluation is possible of most organs and requires minimal instrumentation. The use of retractors and gripping instruments will also allow visualisation of the more dorsally located organs (kidneys, adrenals, etc.).
It is extremely important to use a fixed order in which you explore the abdomen. During the exploratory, you should always start at the left side and proceed from cranial to caudal (i.e., diaphragm, liver, chest wall, stomach, spleen, abdominal wall, etc.). After the left side, you use the same order for the right side. This will prevent that you skip essential organs or abdominal areas. Not all organs can be visualised properly through a median approach. Adrenal glands, kidneys and other dorsally located organs can often better be approached through a lateral approach. Abdominal wall haemorrhage is more likely in a lateral approach compared to a midline approach. Visualisation of deeper (more dorsally located) organs can also be improved by tilting the patient (use gravity) and by using retracting forceps.
In cases of severe ascites, the fluid should be removed before exploring the abdomen. Inserting the trocar of the scope can be done blindly (the chance of puncturing an essential organ is minimal because of the amount of fluid). Some of the fluid is aspirated using an endoscopic suction device. Then the abdomen is inflated and the rest of the fluid is removed under direct visualization.
To obtain a biopsy using laparoscopy is relatively easy. The location of the organ often dictates the entry ports of the laparoscope and instruments. If the location is unknown, a median entry of the laparoscope, just behind the umbilicus is preferred. The falciform ligament is avoided and the whole abdomen can be visualized easily. There are two methods of obtaining a biopsy specimen that are propagated:
- Using cutting or coagulating instruments through separate entry ports.
- Using specific biopsy instruments (Tru-Cut, sure cut) without a separate entry port.
Almost any organ can be biopsied using one of these techniques. Haemorrhage caused by the biopsy instrument can be stopped using coagulation, suture material or application of thrombin-impregnated gelatine. An excisional biopsy can be performed in selected cases. For instance, an abnormal lymph node may be obtained through careful dissection and coagulation of the afferent and efferent vessels.
Amongst advanced laparoscopic procedures in human medicine, laparoscopic adrenalectomy (LA) has become a standard-of-care procedure for resection of most primary adrenal tumors. There is now gathering evidence that laparoscopic adrenalectomy may represent a very reasonable option for resection of non-invasive adrenal tumors in small animal patients.
The author prefers a sternal approach: In a full sternal position the dog is placed on its sternum with a cushion between its hind legs lifting the pelvis of the table. The two hind legs are placed besides the cushion in a splayed leg position. The purpose of this recumbency is to lift the abdomen as far from the table as possible, preferably in a hanging position. This often requires taping the dog especially on the nonsurgical site to handles of the table to increase stability. The sternal position makes the organs ‘suspend’ in the abdomen and eliminates the need for pushing organs away during the procedure. The visibility of the adrenal gland is much improved during this position technique. If the kidney is closely associated with the adrenal gland, cutting the retroperitoneal attachment cranially or over the full length of the kidney will also increase visibility. In this way you create an open retroperitoneal approach.
For LA in sternal recumbency, ports are placed in a semicircular line starting halfway the ribcage and ending at the middle of the ilial wing. The circle is pointing upwards. The first trocar inserted is the camera port on the highest point of the circle, 1–2 cm under the epaxial abdominal muscles and preferably before the left kidney (if palpable). The authors prefer to use an open approach using a turn trocar under endoscopic visualization. As soon as the abdomen is entered, CO2 is insufflated and one or 2 trocars are inserted cranial and caudal to the camera trocard, using the same line (i.e., slightly ventral to the camera. For a sternal approach, either a 30 degree or 0 degree scope can be used. The 30 degree will need to be placed a bit more dorsal than the 0 degree scope. For a retroperitoneal approach, the 30 degree scope is preferred.
The right adrenal approach is similar but placed a bit more cranial. Visualisation can be improved by cutting the renohepatic ligament. A retroperitoneal approach is preferred for a right-sided large adrenal gland.
The main advantage of thoracoscopy is the avoidance of a large thoracotomy incision. Thoracotomy incisions are associated with a large amount of discomfort, a long recovery period, intensive care and large obvious scars. The main disadvantage of thoracoscopic surgery is the limited visibility and small working space caused by the chest wall and insufflation of the lungs.
Blunt trocars are entered using a small entry hole (made by a mosquito) and pressure. The scope entry port is made first. A thorough exploration of the thorax and lung lobectomy is only possible when the lungs are partially insufflated. One-sided lung ventilation can be achieved using a specialized double-lumen (bronchus-blocking) tracheal tube. This will cause one side lung collapse and excellent visibility in the chest. Thoracoscopy can be used for multiple procedures such as exploration, biopsy, pericardectomy, thoracolumbar disc fenestration and lobectomy.
Lung lobectomy in dogs is a relatively easy procedure using thoracoscopy because of the division of all the lung lobes. The hilus of the lung lobe is relatively narrow compared to a human lung lobe and often allows a single endoscopic stapler to do the job. The stapler is inserted, after the hilus is sufficiently visualized, and placed carefully around the hilus. Care must be taken not to lacerate the hilar vein and artery. After placement, the staple is closed and fired. The stapler places 4 rows of staples and cuts in between. The lung is removed from the thorax using a sterile glove or specially designed bag. Closure of the entry ports is routine.
1. Mayhew PD, Kirpensteijn J. Laparoscopic adrenalectomy. In: Mayhew PD, Fransson BA, eds. Small Animal Laparoscopy and Thoracoscopy. John Wiley and Sons; 2015:156–166.