ABSTRACT: Ovario-hysterectomy is probably one of the most common procedures on any veterinary practice's daily list. While we see it as a routine procedure, it is easy to forget that it is major abdominal surgery for the patient and many owners find putting their pet through an elective surgical procedure a difficult decision to make.

Laparoscopic ovariectomy reduces risk of wound infection, is less painful and causes less soft tissue damage than the traditional method.1 The disadvantages associated with this method are that the equipment is very expensive and a small proportion of procedures will be converted to laparotomy if there are complications, such as bleeding, equipment failure, uterine disease or pregnancy.

Initial time and training of staff can also be a disadvantage in a busy practice environment, but once staff are fully trained, the surgical time will be between 30 and 60 minutes. In dogs weighing less than 10kg, there is not always any benefit to laparoscopic surgery as the surgical time may not be any shorter, and the incision size is not significantly reduced using 5mm equipment.

The technique described in this article refers to a two-portal method using an ovariectomy hook. There are other methods that can be used for this procedure, and as well as a wide choice of equipment available on the market.

Figure 1: Basic laparoscopic kit, 5mm rigid endoscope, ovariectomy hook with weighted handle, hot blades, and camera and light cable

The procedure

The patient is anaesthetised and placed in dorsal recumbency in a trough. It is important that this is on an operating table that can be adjusted to lower the head and tilt to either side. This helps the surgeon to locate and visualise the ovaries and to cauterise them without damaging surrounding structures.

The abdomen is clipped from just below the ribs to the inguinal region, and prepared and draped as for any abdominal surgery. It is important to make the clipped area wider than normal on the lateral margins, as the surgeon may need to handle this area when repositioning the patient during the procedure, and for placement of the ovariectomy hook.

The instruments and surgical kit are opened for the surgeon, including the light cable, endoscope and camera cables. The cables may be sterilised using ethylene oxide (EO) gas, or can be placed in cold sterilising solution. If the latter is used, sterile water should be on hand to rinse the cables as they are removed from the solution, and they should be thoroughly dried by the surgeon, using sterile swabs, before being placed in the surgical field and plugged into the relevant machines.

Most rigid endoscopes are autoclavable at low cycle (121°C), but depending on the type and reliability of the practice autoclave, you may choose to cold sterilise. All other autoclavable instruments can be sterilised together in a large instrument tray to be handed to the surgeon for him or her to arrange on the trolley as needed. The light cable, camera cable and insufflator tubing are all clamped to the drapes to keep them within the sterile surgical field, and the ends passed to the unsterile assistant to plug in to the relevant ports on the light source, processor and insufflator. Once all the equipment has been plugged in and switched on, the camera can be white balanced.

The first cannula is inserted through the midline, caudal to the umbilicus, by making a small skin incision with a scalpel blade and using a trocar to penetrate the muscle layer – it is important at this point that the surgeon elevates the abdominal wall and inserts the cannula carefully to avoid penetrating the spleen or liver and causing haemorrhage.

The cannula is secured with 1 metric monofilament suture and the endoscope inserted to check positioning. A second cannula is placed cranially in the same manner to facilitate insertion of instruments (Figure 2). Once both ports are secure, the insufflator tubing can be attached to one of the ports and the abdomen inflated with C02 to 12-15mmHg. The level of pneumoperitoneum needed may vary depending on the size and conformation of the patient.

Figure 2: First cannula placed through the midline caudal to umbilicus, second cannula placed cranially (green and black bung)

With the head end of the table tilted downwards and away from the surgeon, the first ovary can be located. The right ovary is usually more easily located, so the surgeon(s) will be positioned on the left side of the patient for the start of the procedure. A blunt-ended probe should be used to handle the tissues whilst locating the ovary. Once found, grasping forceps are used to secure it and elevate it towards the abdominal wall (Figures 3 & 4).

Figure 3: Grasping vary uterus

Figure 4: Grasping forceps and ovary and kidney

The ovariectomy hook is inserted through the body wall and then through the ovary. Transillumination from the endoscope helps the surgeon find the correct insertion point for the hook – the handle of the hook is weighted so that it can be left in place, holding the ovary in its elevated position ready for cauterisation. The grasping forceps can now be removed leaving a vacant port for the electro-cautery blades (hot blades) which also have a blunt blade to provide a cutting action as well as cautery. This blade has a separate control at the headpiece as well as a fully rotating shaft and ratchet lock.

The instrument is plugged into a standard cautery unit and, once in place, cuts and coagulates the ovary in seconds, being careful to avoid the body wall – it is important that all other structures are avoided when using an ovariectomy hook, as the hook elevates the ovary away from the abdominal contents and towards the body wall.

The hot blades are removed and replaced with grasping forceps to secure the ovary, the hook is removed and the ovary is extracted with the cannula via the original incision, which may need to be extended slightly to accommodate its removal. The surgeon can inspect the ovary to make sure all ovarian tissue has been removed before moving to the other side to repeat the procedure. The anaesthetist and unsterile assistant will need to move instrument trolleys and reposition the operating table to tilt in the opposite direction. Two monitors – or alternatively one monitor on a swinging arm – will make the transition easier.

Once the second ovary has been removed, and
the surgeon is content that there is no haemorrhage, the incisions can be closed with absorbable polyfilament suture (Polyglactin 910) and covered with small post-operative dressings, while the patient recovers from the anaesthetic. Because the ovariectomy hook is very small and extremely sharp, there is no need to suture this wound.

Choice of premedication, anaesthetic agents, antibiotic therapy and post operative analgesia are at the discretion of the veterinary surgeon, although nurses should not use nitrous oxide as an analgesic during this procedure, owing to its ability to cause bowel distension which may impair the surgeon’s field of vision.

Nursing considerations

It is advisable to have one nurse who acts as an unsterile assistant and another who monitors the patient – to try and carry out both roles, especially once pneumoperitoneum is achieved, may be to the detriment of the patient.

The main priority of the assistant should be the set-up and functionality of the equipment. The client will have been taken through a lengthy and detailed consultation and have signed consent for laparoscopic ovariectomy, and it would be disastrous to have to call them and ask for permission to convert to laparotomy purely through equipment failure alone.

The monitors, cables, light source and processor should all be tested prior to induction of anaesthesia and the cables and camera immersed in cold sterilisation fluid, if EO is unavailable. The surgical kits should all be checked to make sure packaging is intact and that they have not exceeded their expiration date. The insufflator and C02 canister should be checked – along with the cautery unit – to make sure everything is in working order. A written check list is useful to make sure nothing is forgotten.

The hot blades described above are manufactured as single-use items for human use and cost around £200. If carefully maintained, they can be cleaned and re-sterilised using EO, but it is useful to have a back-up set in case of failure, as they can by no means be used indefinitely.

As far as the nurse in charge of anaesthesia is concerned, all the usual checks should be carried out on the anaesthetic machine and breathing system. All the standard items used for any procedure should also be gathered – iv catheters and fluids, induction agent, endotracheal tube and tie, heat pad/Bair Hugger machine and blanket, anaesthetic record, chlorhexidine solution and swabs for patient preparation.

In our hospital, we use a multi-parameter monitor that includes ECG, temperature probe, pulse oximeter, non-invasive blood pressure and end tidal carbon dioxide (ETCO2). It is important to monitor respiratory function, especially once the abdomen is insufflated. The patient is in dorsal recumbency, with a large amount of gas in the abdominal cavity. This may put pressure on the diaphragm and cause respiratory depression.

It is particularly important to monitor respiratory rate and effort and aim to keep the ETC02 at 35-45mmHg. If the ETC02 rises above this, hypoventilation is occurring and intermittent positive pressure ventilation (IPPV) may be needed.

Summary

The nurse’s role in this procedure is invaluable. It is important that all equipment is well maintained and sterilised in the appropriate manner. It is critical that the procedure runs smoothly to maximise the full advantages of laparoscopy (minimal surgical time and less soft tissue handling), for the patient.

After the procedure, all instruments must be taken apart and cleaned thoroughly using an ultrasonic cleaner and enzymatic instrument cleaning solution, as blood and tissue can be trapped in the lumen and side ports of the cannulae. Once dry, they should be lubricated and re-assembled ready to be autoclaved. Hot blades can be wiped with detergent and the tips immersed in cleaning solution. Once dry they can be sterilised using EO unless they are autoclavable re-usable instruments.

The camera and light cables can be wiped with detergent and cold sterilised or packaged for EO. The rigid endoscope can be immersed in cleaning solutions; paying particular attention to the tip – using a soft brush to remove any contamination. It can then be autoclaved, or sterilised via EO or cold sterilised prior to the next application.

Dogs that have undergone laparoscopic ovariectomy are more comfortable and less painful post operatively than dogs that have been spayed using the traditional technique, and also have a faster wound healing time.2 Patients are prescribed NSAIDs post operatively and are checked five to seven days later when clients are always happy to report that their pet has recovered well and it has been difficult to keep them rested!

In older bitches, or bitches that have uterine disease, a laparoscopic ovariohysterectomy should be performed. The procedure is performed in a similar manner but the initial incisions do have to be increased in size in order to pull the uterus through without complication.

Laparoscopic equipment can also be used for other procedures such as liver and splenic biopsies and retained abdominal testicles. In dogs with retained testicles, laparoscopy reduces surgical time and incision length, as well as soft tissue damage. Once the testicle has been located, it is pulled through the abdominal wall, ligated and removed. Clients are usually compliant and willing to pay a surcharge for laparoscopy once the benefits have been fully explained, and it is always rewarding to nurse these patients peri- and post-operatively.

Author

Claire Defries DipAVN (Medical) RVN

Claire trained and qualified in a small animal general practice in North London in 2001. She then went on to work as a medicine nurse at the Queen Mother Hospital for Animals. In 2004, she became senior diagnostics nurse responsible for all diagnostic areas of the hospital including endoscopy. Whilst working in the hospital she gained the Diploma in Advanced Veterinary Nursing, and is now head nurse at Wood Street Veterinary Hospital.

References

1.   WILLIAM, T. N., CULP, V. M. D., PHILIPP, D., MAYHEW and BROWN, D. C. (2009) The Effect of Laparoscopic Versus Open Ovariectomy or Postsurgical Activity in Small Dogs. Veterinary Surgery 38 (7): 811-817.

2.   DUPRE, G., FIORBIANCO, V., SKALICKY, M., GULTIKEN, N., AY, S. S., FINDIK, M. (2009) Laparoscopic Ovariectomy in Dogs: Comparison between Single Portal and Two-Portal Access Veterinary Surgery 38 (7): 818-833.

Veterinary Nursing Journal • VOL 25 • No10 • October 2010 •