Suturing and stapling in elective procedures

Routine elective procedures, including ovariohysterectomy, castration, dewclaw removal and feline declaws, are the most common procedures in veterinary medicine. Because of their routine nature, it is easy to put little thought into the materials and methods used for ligation of transected vessels and closure of the wounds. While these procedures are straightforward, overall complication rates have been reported of 1 to 24 percent, with severe complication rates of 1 to 4 percent. Contemporary suture and wound closure manufacturers currently provide the practicing veterinarian with an ample armamentarium to provide safe and reliable wound closure. Critical evaluation of the materials and methods used in the procedure can be beneficial in reducing complications.

In addition to medical factors, economic factors will affect the choice of suture material, patterns and the use of stapling equipment. The cost of the material and equipment must be considered and viewed in light of savings in time and patient morbidity.

Use of vascular clips in general surgery

Ovarian pedicle hemostasis can be achieved through the use of suture or stapling devices. Factors influencing the choice of materials used for hemostasis include the size of the patient, the amount of perivascular fat in the pedicle, the friability of the pedicle, the stage in the heat cycle, security of the hemostatic method, cost of the materials, ease of application and individual preference. There are a large number of methods and materials which can be considered. Some of the details and benefits of each will be discussed.

The most common methods of hemostasis of the ovarian pedicle involve one or more ligatures. The choice of ligature pattern depends heavily on the size and friability of the stump. A single encircling ligature is appropriate for small ovarian pedicles without much perivascular fat. Most surgeons will choose to place a second ligature for increased security. In larger pedicles, a transfixing ligature or Miller's knot is often used.

Suture material chosen for ovarian pedicle hemostasis should be strong, allow good tightness of the ligature to be achieved, and provide good knot security. Generally absorbable suture materials are chosen, however non-absorbable suture material can also be used. Given the affordability, strength and good handling characteristics of modern monofilament absorbable sutures make them a good choice for pedicle ligation. It is important to tie square knots, use five to six throws and leave 5 mm tails.

A simple stainless steel vascular clip can be used to ligate smaller ovarian pedicles, like those in cats and small dogs (Figure 1, p. 10). It is helpful to use a vascular clip that closes first at the tip to avoid slippage of the ligated material. This device is best used on ovarian pedicles in small dogs, ferrets, rabbits, reptiles and cats. The tissue to be ligated must fit comfortably in the jaw of the instrument and one should avoid the temptation to include more tissue. Vascular clips are also useful in splenectomy, amputation and ligation of the short gastric vessels, but can be useful in ligating any small vessel. The vascular clips are intended to be left permanently in place.

Figure 1: A stainless steel vascular clip is used to ligate smaller ovarian pedicles like those in dogs and cats.

The devices can be resterilized by ethylene oxide or Sterrad®. These devices apply a single vascular clip of approximately 7 mm in length. Their primary advantage is the speed and ease of application. The ovarian pedicle can be double ligated in a matter of seconds.

Larger ovarian pedicles are too wide for a single vascular clip. These pedicles can be ligated using a synthetic monofilament or braided absorbable suture.

Uterine stump

This structure can present problems as it may be very large and friable in an older animal. In some cases, the use of a circumferential ligature is not appropriate. I recommend using an absorbable monofilament transfixing ligature for the uterine artery and vein. The actual stump can be oversewn using a single continuous suture pattern, a horizontal mattress or a conventional Parker-Kerr closure. It is important to securely close the uterine lumen.

Spermatic cord ligation

I recommend using an open castration method so that the blood vessels are ligated separately from the tunica. In some cases, we have observed significant post-operative hemorrhage due to retraction of the spermatic vasculature. One can safely use an absorbable monofilament suture or a vascular clip. I recommend the use of double ligatures or vascular clips on each testicular artery and vein.

Table 1.

Body wall closure

Secure and safe closure of every abdominal incision is paramount. We routinely use a simple continuous suture of an appropriately sized absorbable monofilament. When using a simple continuous method of closure, one should begin and end with simple square knots with two to three extra throws. In general, when using sutures for ligation or closure, it is important to use proper square knots, use five to six throws on each knot and at least 5-7 mm tails. It has been shown that continuous incorporation of the peritoneum with the body wall is not necessary; however, I prefer incorporating the peritoneum whenever possible. Continuous closure of the peritoneum is more important in cases with impaired wound healing or an abdominal transudate or exudate.

In cases with possible abdominal sepsis, delayed healing or the presence of significant amounts of abdominal transudate or exudate, we use a non-absorbable suture. Using a simple continuous suture pattern for abdominal wall closure has been shown to be as safe and efficient as using simple interrupted sutures. In either case appropriate suture size, proper knot technique and security is important. In most routine cases using an absorbable monofilament for abdominal closure is satisfactory. In general, this type of suture material maintains +75 percent of its strength during the critical time for abdominal wound healing.

Dewclaws

There are several different methods of skin closure, including the use of surgical adhesives, use of absorbable monofilament or simply bandaging the site. In general, we recommend using an appropriate size absorbable monofilament suture. In mature animals, it is important to ligate the digital blood supply and accurately appose the skin edges. In neonates, one may use either a small hemostat or scissors to clamp and remove the dewclaw and then appose the skin edges with suture.

Skin closure

The options for skin closure include skin staples, intradermal sutures and skin sutures. Skin staplers have enjoyed more widespread use in veterinary surgery over the last decade (Photo 1). Staplers have become more affordable, and their ease and speed of application are primarily responsible for their popularity (Table 1, p. 11).

Photo 1: During the last decade, skin staples have offered veterinarians an easier and more pratical procedure for closing wounds and surgical sites.

There are several important points to remember for skin closure.

• Skin sutures or staples are placed 3-5 mm apart and at least 5 mm from the skin edge.

• It is important to place sutures or staples to accurately approximate the skin edges. Sutures tied too tightly may cause tissue strangulation and cause tissue necrosis. Sutures tied too loosely fail to accurately appose the skin edges.

• In general using a series of simple square knots is recommended.

• Use a reverse cutting needle so that the flat edge of the needle hole faces the incision.

• Remember the role of skin suture is to appose skin edges, not "hold everything in."

Conclusion

There are several acceptable methods for tissue apposition, closure and ligation. Automated stapling or ligation devices offer the advantage of speed, simplicity and versatility. Regardless of the method chosen for wound closure and ligation, basic principles of knot security, tissue apposition and proper technique are important factors to remember.

Suggested Reading.

Dr. Taylor is the owner of Alameda East Veterinary Hospital in Denver. He received his veterinary degree from Texas A & M College of Veterinary Medicine. Dr. Taylor has a master's degree in veterinary surgery from the University of Colorado College of Veterinary Medicine (CSU). He is a diplomate of the American College of Veterinary Surgeons. Dr. Taylor serves as a clinical affiliate to CSU's veterinary teaching hospital.