by Ken Sinervo, MD FRCSC ACGE, Medical Director
Since the previous newsletter on adhesions, there have been many promising products to reach the market, with mixed results. While many of our ideas regarding adhesion formation remain unchanged, we are continuously examining other new ancillary therapies to help reduce the incidence of adhesions.
The incidence of adhesion formation depends on many factors. Patients with advanced stages of endometriosis (stage III and IV) often have a significant amount of adhesions prior to any surgery because endometriosis itself can cause adhesions to form. The amount of raw peritoneal surfaces left following excision surgery may help us anticipate the likelihood of adhesion formation. The use of adhesion barriers often helps to reduce this risk.
There remains no substitute for excellent surgical technique. Adhesions can be separated sharply or bluntly, however, an approach that minimizes tissue injury and excessive use of cautery is preferable. This includes minimizing injury to tissues through the careful use of atraumatic instruments that do not crush tissue or leave denuded surfaces. Preventing blood loss is important as intra-abdominal blood can increase the chances of adhesion formation, When bleeding cannot be prevented, bipolar cautery is used to control it. Copious irrigation helps to remove any remaining intra-abdominal blood. Finally, the judicious of carefully selected sutures may help prevent foreign body reactions.
A number of products have been used to help minimize the formation of adhesions. Barrier agents include non-absorbable barriers, absorbable barriers and fluids. These agents prevent adhesions by physically separating damaged tissues during peritoneal healing, the time during which adhesions form. This healing period is usually considered to be a few days to a few weeks.
Non-absorbable agents include GoreTex and Shelhigh No-React. These agents were initially used during heart surgery. They must be sutured into place, and because they do not dissolve, must theoretically be removed at a later date to prevent fistula formation. The need for a second surgery has limited their widespread use in gyn surgery.
Absorbable barriers include Interceed and Seprafilm. Interceed in derived from oxidized regenerated cellulose. It is a mesh that is draped over injured tissue and does not require suturing. Within eight hours, it forms a gelatinous protective layer that is absorbed within two weeks. There are numerous studies that have demonstrated a reduction in adhesion formation when Interceed has been used. In general, a 50% reduction in the incidence of adhesions occurs with the use of Interceed. One potential disadvantage of Interceed is the requirement of complete hemostasis. If bleeding is not completely stopped, this may increase the risk of adhesions.
Seprafilm is a bio-absorbable membrane derived from sodium hyaluronate and carboxymethylcellulose. Within 24 hours of placement, the film becomes a hydrated gel that is absorbed by the body within seven days. It has been shown to reduce the incidence of adhesions during gynecological and bowel surgery. These studies have been limited to laparotomy and the stiff nature of Seprafilm likely prevents its use during laparoscopy.
Absorbable fluid adjuvants have many advantages to barrier agents such as Interceed and Seprafilm because they coat all surfaces, whereas barrier agents are placed over areas considered to be most likely to form adhesions. Intergel, an 0.5% form of ferric-coated hyaluronic acid (hyaluronic acid is a component of body tissues and fluids such as peritoneal fluid), was shown in a number of studies to reduce the risk of adhesion formation by 40 - 50%. Unfortunately, Intergel was withdrawn from the market following reports of adverse reactions including post-operative pain, possible foreign-body reaction and adhesion formation.
Spraygel is a new product that is currently in clinical trials in the United States. Two polyethylene glycol (PEG)-based liquids are mixed during spraying and form an adherent absorbable hydrogel. It adheres to the tissues that it is sprayed to and remains intact for 5-7 days, the critical period of healing, and then degrades into an absorbable and easily excreted by-product. The frequency and amount of adhesions were decreased in initial studies by about 70%. Spraygel will likely not be available in America for a few years.
In conclusion, the use of barrier agents likely helps to decrease the incidence of adhesion formation. When used in conjunction with excellent surgical technique, meticulous hemostasis and careful tissue handling, the risk of adhesion formation is reduced, but not completely eliminated. In our experience, the risk of adhesions resulting in a need for a subsequent surgery is approximately 10-15%. Repeat surgery for adhesions in these cases is usually less extensive and does not usually involve the same amount of dissection that led to their formation in the first place, namely, moderate or severe endometriosis.