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The prevention of postoperative pelvic adhesions: An animal study comparing barrier methods with dextran 70
The prevention of postoperative pelvic adhesions: An animal study comparing barrier methods with dextran 70 MICHAEL
R.
SOULES,
LARRY
DENNIS,
ALVIN
BOSARGE
IjONALD Keesler
E.
Air
Force
M.D.
M.D.
MOORE, Base,
M.D.
Mississippi,
and
Seattle,
Washington
There are two major approaches to the prophylaxis for adhesions: chemical methods (e.g., dextran) and barrier methods. Theoretically, dextran prevents the formation of adhesions by a surface-coating or hydroflotation effect, whereas the barrier methods either prevent the formation of or mask adhesions by covering and isolating the injured area with an inert substance. This study compared the efficacy of two different concentrations of dextran 70 and various barriers in preventing the formation of adhesions in the female rabbit pelvis. Symmetrical cut and scrape lesions were made on both sides of each rabbit’s uterus; for the barrier-treated animals, the lesions on one side were covered with a barrier, and the contralateral side served as a control. The barriers tested were: Gelfilm, Surgicel, Silastic, Gelfoam paste, amnion, peritoneum, and omentum (five rabbits par subgroup). The same cut and scrape lesions were induced in 16 additional rabbits in the chemical group. These rabbits were subsequently treated with 10 ml/kg of intraperitoneal 6% dextran 70 (five rabbits), and 32% dextran 70 (five rabbits), and were compared with six external control rabbits. The severity of the adhesions that formed was graded by a numerical scoring system. The barrier methods tested resulted, generally, in an increased formation of adhesions when a comparison was made with control and with dextran-treated animals. The degree of formation of adhesions in the dextran-treated rabbits did not differ from that in the control animals. The data suggest that the barrier methods actually promote the formation of adhesions whereas the findings with dextran 70 were inconclusive. (AM. J. OBSTET. GYNECOL. 143:629, 1962.)
PREVENTION of both the initial formation and the recurrence of intraperitoneal adhesions is of paramount importance after abdominal or pelvic operations. Realistically, every surgeon who performs abdom-
THE
From the Clinical Research Laboratory, and the Depatiment of Obstetrics and Gynecology, United States Air Force MediGal Center, Keesler Air Force Bme, and the Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Received
for publication
Revised Februaq Accepted March
December
9, 1981,
24, 1982. 18, 1982.
Reprint requests: Michael R. Soules, M.D., Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, RH-20, University oj Washington School of Medicine, Seattle, Washington 98195.
inal operations must contend with either the occurrence or reformation of adhesions every time he operates. In gynecologic infertility, approximately 15% to 20% of all infertility is secondary to adhesions that affect the uterus, tubes, or ovaries.’ Operations on the female pelvic organs (in contrast to bowel operations) present a unique set of circumstances in regard to the formation of adhesions. There is less intrinsic motility in the female organs, and blood tends to pool in the pelvis; both of these circumstances tend to promote the formation of adhesions. Therefore, the prevention of postoperative adhesions is a pertinent topic for all gynecologists, and especially for those who treat infertile women. Recognition of the broad scope of this problem has not led to totally successful measures to prevent the formation of adhesions. Good operative technique with 829
August Am. J. Obstet.
I
TREATMENT
1 I
CONTROL
1, 1982 Gynerol.
methods continue to be promoted in standard gynecologic textbooks as an efficacious means of inhibiting the formation of adhesions.11-‘4 Free grafts of peritoneum or omentum are commonly recommended in association with such procedures as myomectomy,‘z, I3 infer” and conservative endometriosis tility operations,“. operations.‘* The use of these grafts has, apparently, avoided any real scientific scrutiny. In consideration of these issues, this study compares the efficacy of two different concentrations of dextran 70 and various barriers (three natural and four synthetic) in preventing the formation of adhesions in the female rabbit pelvis.
Material and methods
Fig. 1. Indicated
on this drawing of the female rabbit reproductive system are the locations of the bilateral induced lesions (cut and scrape). When barrier methods were tested, the
barriers were placed on one side of the reproductive tract, and the contralateral side served as a control.
gentle handling of tissues, hemostasis, and irrigation will inhibit the formation of adhesions but not totally prevent their occurrence. Over the years, many drug regimens have been tested, both intraperitoneally and systemically, for their ability to prevent adhesions. Heparin, glucocorticoids, proteolytic enzymes, iodine solutions, and antibiotics are some of the agents that have been employed. These “chemical” methods have had mixed and often discrepant success.2-5 Of all the chemical methods, the use of 32% dextran 70 appears to have the greatest potential as noted in several recent animal studies.6, 7 Another major approach to prophylaxis for adhesions has been the use of “barrier” methods. The concept here is to use a substance to cover and isolate the injured area and thereby mask and/or prevent the formation of adhesions. Materials used as barriers have included omenturn,’ polythene,” and amnion.” Barrier
Animals and operative procedures. The subjects of this study were 54 female New Zealand white rabbits (4 to 5 kg in weight). All of the rabbits underwent two laparotomies 4 weeks apart under sterile conditions. An anesthetic mixture composed of ketamine, 80 mgiml, and acepromazine, 1.6 mg/ml, was administered subcutaneously. No antibiotics were employed. For the first laparotomy, a midline abdominal incision was made after the surgeon had cleaned all visible talc off his gloves. When the abdomen was entered, the bowel was carefully packed with a single 4-by-4 gauze pad that had been soaked in normal saline solution. Two equal areas (approximately 1.5 by 2.0 cm) on the lateral sides of the uterus were scraped with a No. 10 scalpel blade for 2 to 4 minutes in each animal. Then, these same areas were rubbed vigorously with a dry 4-b+ gauze pad. Both scraped areas were judged by the surgeon to be equal in erythema and serosanguineous discharge after this phase of the procedure (scrape lesion). Next, a 1 cm segment of uterine wall was removed by sharp dissection (cut lesion) in two symmetrical areas on the anterior uterine horns. No attempt at hemostasis was made. Fig. 1 is a drawing of the induced lesions. At this point in the initial laparotomy, the surgeon was informed as to which side of the animal’s uterus had been previously randomly selected for treatment with a barrier (no barrier was applied to the uteri in the two groups that received intraperitoneal dextran). The barriers were applied to the designated side of each uterus, and the contralateral side served as an internal control. Prior to closure, the peritoneal cavity was lavaged with normal saline solution, and all clots and residual saline solution were removed. There were three deaths in the postoperative interval (two related to the anesthetic, and one from peritonitis). Fifty-one rabbits underwent a second laparotomy approximately .4 weeks later. The presence and severity
Volume Number
143 7
of postoperative adhesions were graded according to the scoring system in Table I. Whenever the treated and control areas of injury were found to have become adherent to each other, the score for the two areas was not tabulated because the lesions were no longer considered to be independent. This circumstance led to an unequal number of cut and scrape lesions in some groups. The treatment code was not revealed until after the scoring was completed. The barrier methods used in this study were as follows. Peritoneum (five animals). A segment of parietal peritoneum was sharply removed from the anterior abdominal wall. The avascular peritoneal segment was divided, with a piece placed over the entirety of each uterine lesion and was sutured in place with interrupted 4-O chromic suture.* Omentum (jive animals). A segment of the omentum was obtained from the upper abdomen. These avascular omental grafts were attached with 4-O chromic suture in the same manner as the peritoneal grafts. Silastic? (jive animals). Appropriate size segments of 0.007 inch reinforced Silastic were cut and sutured in place over the designated scrape area with interrupted 4-O silk sutures around the perimeter. Likewise, segments of 0.005 inch nonreinforced Silastic were sutured in place over the designated cut area. SurgicelJ: (Jive animals). Sterile segments of Surgicel, an absorbable knitted fabric, were saturated with about 1 ml of 32% dextran and were sutured in place with interrupted 4-O polyglycolic acid sutures. Gelfilm§ (jive animals). Sterile segments of Gelfilm, an absorbable gelatin film, were placed over the designated uterine lesions and sutured in place with 5-O polyglycolic acid sutures. Amnion (jive animals). Amnion was obtained at 28 days’ gestation from a female rabbit. The amnion was carefully separated from the chorion, washed free of blood with saline solution, and sutured in place over the designated uterine defects with 5-O polyester sutures. It was not always possible to clearly identify the mesenthyme side of the amnion. *The particular sutures and needles that were used throughout the experiments in the application of the various barriers were selected for being most suited to the material being applied. The sutures always occupied a very minimal area in relationship to the total barrier. TSilastic, medical grade silicone elastomer, Dow Corning, Midland, Michigan. $Surgicel, knitted fabric made from oxidized cellulose, Johnson and Johnson Company, New Brunswick, New Jersey. ~Gelfilm, sheets of gelatin film 0.075 cm thick, The Upjohn Company, Kalamazoo, Michigan.
Prevention
Table
I. Adhesion
Grade 0
1 2 3 4
of postoperative
scoring
pelvic
adhesions
831
system Description
No formation of adhesions Thin and narrow, easily separable adhesions Thick adhesion, less than 1 cm wide, limited to one area Thick adhesions, greater than 1 cm wide, wide-spread Adhesions to other viscera and/or the abdominal wall
Gelfoam*paste (five animals). Five sheets of 2 by 6 by 0.7 cm gelatin sponge (Gelfoam) were mixed with 20 ml of 32% dextran 70 solution with a mortar and pestle in sterile fashion. This paste was applied to the designated scrape and cut areas on the uteri and allowed to air dry. In addition to the barrier-treated animals, six animals served as external controls, and 10 others were treated with intraperitoneal dextran 70. External controls (six animals). These rabbits had the same scrape and cut lesions induced on their uteri but were not treated. 6% Dextran 70 (five animals). Fifty milliliters of this solution was instilled into the peritoneal cavity of each rabbit after the induction of the standard uterine lesions (approximately 10 to 12.5 ml/kg). Hyskont (five animals). After the animals had been prepared in standard fashion, then 10 ml/kg of 32% dextran solution was placed in the peritoneal cavity. Statistics. The data were analyzed by the MannWhitney U test.‘s The cut and scrape lesions were analyzed separately for each group. For instance, when a given barrier was compared to the combined controls, then the adhesion scores for the barrier-treated scrape lesions were statistically compared to the adhesion scores for the scrape lesions of the combined external and internal controls. The cut lesions were handled in a similar fashion.
Results The cut lesions generally produced more adhesions than the scrape lesions. The dominance of the cut over the scrape lesions occurred in most animal groups studied (mean f SEM indicated for the following examples): all barriers combined (3.2 c 0.20 versus 2.2 2 0.23); all internal controls combined (2.1 ? 0.34 versus 0.78 ? 0.17); and all external controls combined (1.7 + *Gelfoam, sponge made from a purified gelatin solution, The Upjohn Company, Kalamazoo, Michigan. tHyskon, 32% dextran 70 solution in dextrose (10% w/v), Pharmacia Laboratories, Piscataway, New Jersey.
August 1, 1982 Am. J. Obstet. Gynecol.
Table II. Barrier
methods
and dextran
70 versus controls
(mean adhesion
I
Adhesion n
scores) score (mean
Scrape
+ SEM) n
Cut
Treatment group Gelfilm Omentum Peritoneum Silastic paste Gelfoam Amnion Surgicel All Barriers combined 6% Dextran 70 32% Dextran 70 Dextran 70 combined
5 5 4 5 5 r ii 34 10 10 20
3.20 3.20 2.50 2.60 1.20 1.40 1.10 2.16 1.10 0.55 0.83
+ 2 2 + 2 2 lr: + t 2 2
0.20 0.37 0.87 0.75 0.46 0.40 0.40 0.23 0.48 0.16 0.25
4 5 5 4 4 5 4 31 IO 8 18
3.50 3.20 3.60 3.50 3.25 2.80 2.25 3.16 1.80 1.56 1.69
2 0.29 r 0.37 k 0.24 c 0.50 f 0.48 r?~ 0.73 t 0.85 t 0.20 f 0.39 +- 0.55 t 0.32
Control pup Internal-Gelfilm internal-Omentum Internal-Peritoneum Internal-Silastic paste Internal-Gelfoam Internal-Amnion Internal-Surgicel All internal controls combined All external controls combined Internal and external controls
5 5 4 5 5 5 5 34 12 46
0.50 0.90 2.50 0.40 0.30 0.50 0.70 0.78 0.63 0.74
2 + t 2 t -e +it f f
0.16 0.53 0.96 0.10 0.12 0.16 0.12 0.17 0.32 0.15
4 2 3 1 4 5
2.38 2.00 2.00 4.00 3.25 1.60 0.83 2.14 1.67 1.97
2 0.75 f 2.00 -t 1.15
combined
Table IIIA. Barrier
methods and dextran versus internal and external controls combined (Mann-Whitney U test)
70
Table IIIB. Barrier combined
Treatments
Scrape
Cut
Gelfilm Omentum Peritoneum Silastic Gelfoam paste Amnion Surgicel All barriers combined 6% Dextran 70 32% Dextran 70 Dextran 70 combined
S* S*
NS NS .% NS NS NS NS S* NS NS NS
S = Significant. *z = 2.81; p tz = 2.58; p $z = 1.96; p §z = 3.30; p
c 5 5 5
St St F NS SS NS NS NS
2: 12 34
NS = Nonsignificant. 0.005. 0.01. 0.05. 0.001.
0.43 versus 0.6 + 0.32). These values were all significantly different, with a minimum p value of 0.05. Both types of lesions responded in a similar manner in both the treatment and control groups. The side of the uterus opposite to the barrier-treated side served as an internal control in 35 animals. Six animals served as external controls and received no dextran or barrier. The mean adhesion score of the cut
methods versus dextran (Mann-Whitney U test)
1 zk IfI k k f
0.48 0.75 0.60 0.34 0.43 0.27
70
Treatments
Scrape
cut
Gelfilm Omentum Peritoneum Silastic Gelfoam paste Amnion Surgicel All barriers combined
S* S*
s”:
:: NS NS iz:
z: St NS NS SS
S = Significant. NS = Nonsignificant. *z = 2.81; p 5 0.005. tz = 1.96; p 5 0.05. l‘z = 3.30; p 5 0.001.
lesions for the internal controls (2.1 k 0.34) was not significantly different from the mean adhesion score of the cut lesions of the six external control animals (1.7 * 0.43); this was true for the respective scrape lesions, as well (0.78 it 0.17 versus 0.63 ‘-c 0.32). This finding served to validate the study design and enabled a combination of the control groups for comparative purposes. The mean adhesion scores for the cut and scrape lesions for each of the barriers tested exceeded the adhesion scores for each of the respective internal controls in the majority of the groups studied (Table II). For the scrape lesions, most of the barriers tested had
Volume Number
143 7
significantly more adhesions when compared to the combined control groups (Table IIIA). For the cut lesions, only the peritoneum group had significantly more adhesions when compared to the controls. The Gelfoam paste and Surgicel groups did not have significantly more adhesions than the control groups for either type of induced lesion. The adhesion score for all barriers combined compared to the adhesion score for the combined control groups (cut and scrape lesions) had a highly significant increase in adhesions (Table IIIA). The mean adhesion scores for the dextran 70treated groups were low (Table II). The five animals treated with 32% dextran 70 had the lowest mean adhesion scores (scrape 0.55 f 0.16; cut 1.56 t 0.55) of all groups, including the controls, but this was not significantly different from the external or combined controls. Likewise, the adhesion score for the dextran 70 groups combined was not significantly different from the score for the external and internal controls combined (Table IIIA). The adhesion score (cut and scrape lesions) for the combined 6% and 32% dextran 70-treated animals was significantly less than the adhesion scores for the groups treated with Gelfilm, omentum, peritoneum, and Silastic (Table IIIB). Gelfoam paste had more adhesions than the combined dextran 70 animals only for the cut lesions; the amnion and Surgicel groups were not significantly different from the combined dextran 70 animals. The combined barrier adhesion score was significantly increased over the combined dextran 70 adhesion score with a p I 0.001 (Table IIIB). The barrier methods tested were often associated with an increased number of adhesions in many animals. The barriers themselves were frequently observed to be the focus of an inflammatory response.
Comment The results of this study indicate that generally the use of both natural and synthetic barriers promoted the formation of adhesions. Only the use of Surgicel was not significantly inferior to the controls and dextran 70-treated animals in regard to adhesions; but like most of the other barriers, it also, had a higher mean adhesion score than the controls. The natural barriers, such as omentum, peritoneum, and amnion, are essentially avascular grafts and eventually undergo necrosis. These changes promote deposition of fibrin and inflammation and theoretically would tend to promote adhesions, in agreement with our findings. Previous studies of natural barrier methods have generally been confined to evaluating free grafts of omenturn used more as a plug after bowel injuries83 I63I7 The
Prevention
of postoperative
pelvic
adhesions
833
authors of those studies invariably commented on the large amount of adhesions after the use of free omental grafts. Amnion was significantly inferior to controls when scrape lesions were compared and had higher mean adhesion scores than its internal controls. A previous study concluded that allografts of amnion were efficacious in inhibiting the formation of adhesions after induced bowel injuries in rabbits.‘O The discrepancy between these results and our own may be explained by the use of bowel as opposed to uterine injuries, the use of antibiotics in the first study, and, perhaps, the inability to always identify and place the mesenchyme surface of the amnion toward the injured area in this study. The synthetic barriers tested also promoted the formation of adhesions. Barriers, such as Gelfilm, Silastic, and Gelfoam, will attract an inflammatory response as a part of the degradation process. All synthetic barriers also have the potential to act as foreign bodies. These properties of synthetic barriers would theoretically promote the formation of adhesions, which is in agreement with our findings. It is interesting that the two synthetic barriers (Gelfoam and Surgicel) that were associated with less formation of adhesions than the other barriers were mixed or saturated with 32% dextran 70 prior to their application. Previously, Gelfoam paste had been found to be efficacious in inhibiting the formation of adhesions in pigs.rs Perhaps the differences in induced lesions and in the animal models studied and the use of antibiotics in the previous study would account for the discrepancy in results. Surgicel was found to be effective in preventing the formation of adhesions after induced injuries to the cecum in rats, but again the organ, animal model, and the method of inducing lesions were different from those in the present study.rg The intraperitoneal administration of 32% dextran 70 has been found to be effective in inhibiting the formation of adhesions in recent studies performed in rabbit93 ‘O-** and monkeys.7 It is postulated that bathing the pelvic organs with 32% dextran 70 solution prevents the postoperative agglutination of the fibrinrich injured surfaces and thereby prevents the formation of adhesions. The dextran 70 treatment in this study was clearly superior to barrier methods in preventing the formation of adhesions. But in contrast to previous studies, this study found no difference in the formation of adhesions when the 32% dextran 70 solution was compared to controls. It should be noted, however, that the rabbits treated with 32% dextran 70 had the lowest mean adhesion score of all the groups tested. The four previous studies in a rabbit model that concluded that 32% dextran 70 was effective in pre-
834
Soules
August 1, 1982 Am. J. Obstet. Gynecol.
et al.
venting the formation of pelvic more differences in methodology the current study.6, 2o-22 The conclusion drawn is that and synthetic barrier methods in preventing the formation of
adhesions had one or from each other and the natural (avascular) tested are not effective adhesions and actually
appear to promote the formation of adhesions in most instances. The postoperative administration of intraperitoneal 32% dextran 70 is clearly the leading candidate, on the basis of previous studies, as an effective agent to prevent the initial formation and recurrence of pelvic adhesions.
REFERENCES
1. Behrman, J., and Kistner, R. W.: Progress in Infertility, ed. 2, Boston, 1975, Little, Brown & Company, p. 230. 2. Seitz, H., Schenker, J. G., Epstein, S., and Garcia, C.-R.: Postoperative intraperitoneal adhesions: A double-blind assessment of their prevention in the monkey, Fertil. Steril. 24:935, 1973. 3. Ellis, H.: The cause and prevention of postoperative intraperitoneal adhesions, Surg. Gynecol. Obstet. 133:497, 1971. 4. Gilmore, 0. J. A., Reid, C., Houang, E. T., and Shaw, E. J.: Prophylactic intraperitoneal povidone-iodine in alimentary tract surgery, Am. J. Surg. 135:156, 1978. 5. Kaput-, B. M. L., Gulati, S. M., and Talwor, J. R.: Prevention of reformation of peritoneal adhesions, Arch. Surg. 105:761. 1972. 6. Holtz, d., and Baker, E.: Inhibition of peritoneal adhesions. Reformation after lysis with 32% Dextran 70, Fertil. Steril. 34:394, 1980. 7. DiZerega, G. S., and Hodgen, G. D.: Prevention of postoperative tubal adhesions, AM. J. OBSTET. GYNECOL. 136:173, 1980. 8. Davis, C. B.: Free transplantation of the omentum, JAMA 68:705, 1917. 9. Ellis, H,., Harrison, W., and Hugh, T. B.: The healing of peritoneum under normal and pathological conditions, Br. J. Surg. 52:471, 1965. 10. Trelford-Sauder. M., Dawe, E. I., and Trelford, I. D.: Use of allograft amniotic membrane for control of&a abdominal adhesions. I. Med. 9:273. 1978. 11. Behrman, J., and Kistker, R. W.: Progress in Infertility, ed. 2, Boston, 1975, Little, Brown and Company, p. 360. 12. Ridley, R. H., editor: Gynecologic Surgery. Errors,
13. 14. 15. 16. 17.
18.
19. 20.
21.
22.
Safeguards Salvage, ed. 1, Baltimore, 1974, Williams & Wilkins, p. 28. Tovell, H. M. M., and Dank, L. D.: Gynecologic Operations, ed. 1, Hagerstown, Maryland, 1978, Harper & Row, p. 76. Patton, G. W., and Kistner, R. W., editors: Atlas of Infertility Surgery, Boston, 1975, Little, Brown and Company, p. 103. Siegel, S.: Nonparametric Statistics for the Behavioral Sciences, New York, 1956, McGraw-Hill Book Company, pp. 120-121. Pettet, J. R., Judd, E. S., and Woolner, L. B.: Free omental grafts applied to intestinal anastomoses, Arch. Surg. 72:925, 1956. Finton, W. L., and Peet, M. M.: An experimental study of the use of detached omental grafts in intestinal surgery, Surg. Gynecol. Obstet. 29:281, 1919. Luengo, J., and Van Hall, E. V.: Prevention of peritoneal adhesions by the combined use of Spongostan and 32% dextran 70: An experimental study in pigs, Fertil. Steril. 29:447. 1978. Larsson, B., Nisell, H., and Granberg, I.: Surgicel-an absorbable hemostatic material-in prevention of peritoneal adhesions in rats, Acta Chit-. Stand. 144:375, 1978. Holtz, G., Baker, E., and Tsai, C.: Effect of 32% dextran 70 on peritoneal adhesion formation and re-formation after lysis, Fertil. Steril. 33:660, 1980. Neuwirth, R. S., and Khalaf, S. M.: Effect of 32% dextran 70 on peritoneal adhesion formation, AM. J. OBSTET. GYNECOL. 121:420, 1975. Utian, W. H., Goldfarb, J. M., and Starks, G. C.: Role of dextran 70 in microtubal surgery, Fertil. Steril. 31:79, 1979.
R.
SOULES,
LARRY
DENNIS,
ALVIN
BOSARGE
IjONALD Keesler
E.
Air
Force
M.D.
M.D.
MOORE, Base,
M.D.
Mississippi,
and
Seattle,
Washington
There are two major approaches to the prophylaxis for adhesions: chemical methods (e.g., dextran) and barrier methods. Theoretically, dextran prevents the formation of adhesions by a surface-coating or hydroflotation effect, whereas the barrier methods either prevent the formation of or mask adhesions by covering and isolating the injured area with an inert substance. This study compared the efficacy of two different concentrations of dextran 70 and various barriers in preventing the formation of adhesions in the female rabbit pelvis. Symmetrical cut and scrape lesions were made on both sides of each rabbit’s uterus; for the barrier-treated animals, the lesions on one side were covered with a barrier, and the contralateral side served as a control. The barriers tested were: Gelfilm, Surgicel, Silastic, Gelfoam paste, amnion, peritoneum, and omentum (five rabbits par subgroup). The same cut and scrape lesions were induced in 16 additional rabbits in the chemical group. These rabbits were subsequently treated with 10 ml/kg of intraperitoneal 6% dextran 70 (five rabbits), and 32% dextran 70 (five rabbits), and were compared with six external control rabbits. The severity of the adhesions that formed was graded by a numerical scoring system. The barrier methods tested resulted, generally, in an increased formation of adhesions when a comparison was made with control and with dextran-treated animals. The degree of formation of adhesions in the dextran-treated rabbits did not differ from that in the control animals. The data suggest that the barrier methods actually promote the formation of adhesions whereas the findings with dextran 70 were inconclusive. (AM. J. OBSTET. GYNECOL. 143:629, 1962.)
PREVENTION of both the initial formation and the recurrence of intraperitoneal adhesions is of paramount importance after abdominal or pelvic operations. Realistically, every surgeon who performs abdom-
THE
From the Clinical Research Laboratory, and the Depatiment of Obstetrics and Gynecology, United States Air Force MediGal Center, Keesler Air Force Bme, and the Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Received
for publication
Revised Februaq Accepted March
December
9, 1981,
24, 1982. 18, 1982.
Reprint requests: Michael R. Soules, M.D., Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, RH-20, University oj Washington School of Medicine, Seattle, Washington 98195.
inal operations must contend with either the occurrence or reformation of adhesions every time he operates. In gynecologic infertility, approximately 15% to 20% of all infertility is secondary to adhesions that affect the uterus, tubes, or ovaries.’ Operations on the female pelvic organs (in contrast to bowel operations) present a unique set of circumstances in regard to the formation of adhesions. There is less intrinsic motility in the female organs, and blood tends to pool in the pelvis; both of these circumstances tend to promote the formation of adhesions. Therefore, the prevention of postoperative adhesions is a pertinent topic for all gynecologists, and especially for those who treat infertile women. Recognition of the broad scope of this problem has not led to totally successful measures to prevent the formation of adhesions. Good operative technique with 829
August Am. J. Obstet.
I
TREATMENT
1 I
CONTROL
1, 1982 Gynerol.
methods continue to be promoted in standard gynecologic textbooks as an efficacious means of inhibiting the formation of adhesions.11-‘4 Free grafts of peritoneum or omentum are commonly recommended in association with such procedures as myomectomy,‘z, I3 infer” and conservative endometriosis tility operations,“. operations.‘* The use of these grafts has, apparently, avoided any real scientific scrutiny. In consideration of these issues, this study compares the efficacy of two different concentrations of dextran 70 and various barriers (three natural and four synthetic) in preventing the formation of adhesions in the female rabbit pelvis.
Material and methods
Fig. 1. Indicated
on this drawing of the female rabbit reproductive system are the locations of the bilateral induced lesions (cut and scrape). When barrier methods were tested, the
barriers were placed on one side of the reproductive tract, and the contralateral side served as a control.
gentle handling of tissues, hemostasis, and irrigation will inhibit the formation of adhesions but not totally prevent their occurrence. Over the years, many drug regimens have been tested, both intraperitoneally and systemically, for their ability to prevent adhesions. Heparin, glucocorticoids, proteolytic enzymes, iodine solutions, and antibiotics are some of the agents that have been employed. These “chemical” methods have had mixed and often discrepant success.2-5 Of all the chemical methods, the use of 32% dextran 70 appears to have the greatest potential as noted in several recent animal studies.6, 7 Another major approach to prophylaxis for adhesions has been the use of “barrier” methods. The concept here is to use a substance to cover and isolate the injured area and thereby mask and/or prevent the formation of adhesions. Materials used as barriers have included omenturn,’ polythene,” and amnion.” Barrier
Animals and operative procedures. The subjects of this study were 54 female New Zealand white rabbits (4 to 5 kg in weight). All of the rabbits underwent two laparotomies 4 weeks apart under sterile conditions. An anesthetic mixture composed of ketamine, 80 mgiml, and acepromazine, 1.6 mg/ml, was administered subcutaneously. No antibiotics were employed. For the first laparotomy, a midline abdominal incision was made after the surgeon had cleaned all visible talc off his gloves. When the abdomen was entered, the bowel was carefully packed with a single 4-by-4 gauze pad that had been soaked in normal saline solution. Two equal areas (approximately 1.5 by 2.0 cm) on the lateral sides of the uterus were scraped with a No. 10 scalpel blade for 2 to 4 minutes in each animal. Then, these same areas were rubbed vigorously with a dry 4-b+ gauze pad. Both scraped areas were judged by the surgeon to be equal in erythema and serosanguineous discharge after this phase of the procedure (scrape lesion). Next, a 1 cm segment of uterine wall was removed by sharp dissection (cut lesion) in two symmetrical areas on the anterior uterine horns. No attempt at hemostasis was made. Fig. 1 is a drawing of the induced lesions. At this point in the initial laparotomy, the surgeon was informed as to which side of the animal’s uterus had been previously randomly selected for treatment with a barrier (no barrier was applied to the uteri in the two groups that received intraperitoneal dextran). The barriers were applied to the designated side of each uterus, and the contralateral side served as an internal control. Prior to closure, the peritoneal cavity was lavaged with normal saline solution, and all clots and residual saline solution were removed. There were three deaths in the postoperative interval (two related to the anesthetic, and one from peritonitis). Fifty-one rabbits underwent a second laparotomy approximately .4 weeks later. The presence and severity
Volume Number
143 7
of postoperative adhesions were graded according to the scoring system in Table I. Whenever the treated and control areas of injury were found to have become adherent to each other, the score for the two areas was not tabulated because the lesions were no longer considered to be independent. This circumstance led to an unequal number of cut and scrape lesions in some groups. The treatment code was not revealed until after the scoring was completed. The barrier methods used in this study were as follows. Peritoneum (five animals). A segment of parietal peritoneum was sharply removed from the anterior abdominal wall. The avascular peritoneal segment was divided, with a piece placed over the entirety of each uterine lesion and was sutured in place with interrupted 4-O chromic suture.* Omentum (jive animals). A segment of the omentum was obtained from the upper abdomen. These avascular omental grafts were attached with 4-O chromic suture in the same manner as the peritoneal grafts. Silastic? (jive animals). Appropriate size segments of 0.007 inch reinforced Silastic were cut and sutured in place over the designated scrape area with interrupted 4-O silk sutures around the perimeter. Likewise, segments of 0.005 inch nonreinforced Silastic were sutured in place over the designated cut area. SurgicelJ: (Jive animals). Sterile segments of Surgicel, an absorbable knitted fabric, were saturated with about 1 ml of 32% dextran and were sutured in place with interrupted 4-O polyglycolic acid sutures. Gelfilm§ (jive animals). Sterile segments of Gelfilm, an absorbable gelatin film, were placed over the designated uterine lesions and sutured in place with 5-O polyglycolic acid sutures. Amnion (jive animals). Amnion was obtained at 28 days’ gestation from a female rabbit. The amnion was carefully separated from the chorion, washed free of blood with saline solution, and sutured in place over the designated uterine defects with 5-O polyester sutures. It was not always possible to clearly identify the mesenthyme side of the amnion. *The particular sutures and needles that were used throughout the experiments in the application of the various barriers were selected for being most suited to the material being applied. The sutures always occupied a very minimal area in relationship to the total barrier. TSilastic, medical grade silicone elastomer, Dow Corning, Midland, Michigan. $Surgicel, knitted fabric made from oxidized cellulose, Johnson and Johnson Company, New Brunswick, New Jersey. ~Gelfilm, sheets of gelatin film 0.075 cm thick, The Upjohn Company, Kalamazoo, Michigan.
Prevention
Table
I. Adhesion
Grade 0
1 2 3 4
of postoperative
scoring
pelvic
adhesions
831
system Description
No formation of adhesions Thin and narrow, easily separable adhesions Thick adhesion, less than 1 cm wide, limited to one area Thick adhesions, greater than 1 cm wide, wide-spread Adhesions to other viscera and/or the abdominal wall
Gelfoam*paste (five animals). Five sheets of 2 by 6 by 0.7 cm gelatin sponge (Gelfoam) were mixed with 20 ml of 32% dextran 70 solution with a mortar and pestle in sterile fashion. This paste was applied to the designated scrape and cut areas on the uteri and allowed to air dry. In addition to the barrier-treated animals, six animals served as external controls, and 10 others were treated with intraperitoneal dextran 70. External controls (six animals). These rabbits had the same scrape and cut lesions induced on their uteri but were not treated. 6% Dextran 70 (five animals). Fifty milliliters of this solution was instilled into the peritoneal cavity of each rabbit after the induction of the standard uterine lesions (approximately 10 to 12.5 ml/kg). Hyskont (five animals). After the animals had been prepared in standard fashion, then 10 ml/kg of 32% dextran solution was placed in the peritoneal cavity. Statistics. The data were analyzed by the MannWhitney U test.‘s The cut and scrape lesions were analyzed separately for each group. For instance, when a given barrier was compared to the combined controls, then the adhesion scores for the barrier-treated scrape lesions were statistically compared to the adhesion scores for the scrape lesions of the combined external and internal controls. The cut lesions were handled in a similar fashion.
Results The cut lesions generally produced more adhesions than the scrape lesions. The dominance of the cut over the scrape lesions occurred in most animal groups studied (mean f SEM indicated for the following examples): all barriers combined (3.2 c 0.20 versus 2.2 2 0.23); all internal controls combined (2.1 ? 0.34 versus 0.78 ? 0.17); and all external controls combined (1.7 + *Gelfoam, sponge made from a purified gelatin solution, The Upjohn Company, Kalamazoo, Michigan. tHyskon, 32% dextran 70 solution in dextrose (10% w/v), Pharmacia Laboratories, Piscataway, New Jersey.
August 1, 1982 Am. J. Obstet. Gynecol.
Table II. Barrier
methods
and dextran
70 versus controls
(mean adhesion
I
Adhesion n
scores) score (mean
Scrape
+ SEM) n
Cut
Treatment group Gelfilm Omentum Peritoneum Silastic paste Gelfoam Amnion Surgicel All Barriers combined 6% Dextran 70 32% Dextran 70 Dextran 70 combined
5 5 4 5 5 r ii 34 10 10 20
3.20 3.20 2.50 2.60 1.20 1.40 1.10 2.16 1.10 0.55 0.83
+ 2 2 + 2 2 lr: + t 2 2
0.20 0.37 0.87 0.75 0.46 0.40 0.40 0.23 0.48 0.16 0.25
4 5 5 4 4 5 4 31 IO 8 18
3.50 3.20 3.60 3.50 3.25 2.80 2.25 3.16 1.80 1.56 1.69
2 0.29 r 0.37 k 0.24 c 0.50 f 0.48 r?~ 0.73 t 0.85 t 0.20 f 0.39 +- 0.55 t 0.32
Control pup Internal-Gelfilm internal-Omentum Internal-Peritoneum Internal-Silastic paste Internal-Gelfoam Internal-Amnion Internal-Surgicel All internal controls combined All external controls combined Internal and external controls
5 5 4 5 5 5 5 34 12 46
0.50 0.90 2.50 0.40 0.30 0.50 0.70 0.78 0.63 0.74
2 + t 2 t -e +it f f
0.16 0.53 0.96 0.10 0.12 0.16 0.12 0.17 0.32 0.15
4 2 3 1 4 5
2.38 2.00 2.00 4.00 3.25 1.60 0.83 2.14 1.67 1.97
2 0.75 f 2.00 -t 1.15
combined
Table IIIA. Barrier
methods and dextran versus internal and external controls combined (Mann-Whitney U test)
70
Table IIIB. Barrier combined
Treatments
Scrape
Cut
Gelfilm Omentum Peritoneum Silastic Gelfoam paste Amnion Surgicel All barriers combined 6% Dextran 70 32% Dextran 70 Dextran 70 combined
S* S*
NS NS .% NS NS NS NS S* NS NS NS
S = Significant. *z = 2.81; p tz = 2.58; p $z = 1.96; p §z = 3.30; p
c 5 5 5
St St F NS SS NS NS NS
2: 12 34
NS = Nonsignificant. 0.005. 0.01. 0.05. 0.001.
0.43 versus 0.6 + 0.32). These values were all significantly different, with a minimum p value of 0.05. Both types of lesions responded in a similar manner in both the treatment and control groups. The side of the uterus opposite to the barrier-treated side served as an internal control in 35 animals. Six animals served as external controls and received no dextran or barrier. The mean adhesion score of the cut
methods versus dextran (Mann-Whitney U test)
1 zk IfI k k f
0.48 0.75 0.60 0.34 0.43 0.27
70
Treatments
Scrape
cut
Gelfilm Omentum Peritoneum Silastic Gelfoam paste Amnion Surgicel All barriers combined
S* S*
s”:
:: NS NS iz:
z: St NS NS SS
S = Significant. NS = Nonsignificant. *z = 2.81; p 5 0.005. tz = 1.96; p 5 0.05. l‘z = 3.30; p 5 0.001.
lesions for the internal controls (2.1 k 0.34) was not significantly different from the mean adhesion score of the cut lesions of the six external control animals (1.7 * 0.43); this was true for the respective scrape lesions, as well (0.78 it 0.17 versus 0.63 ‘-c 0.32). This finding served to validate the study design and enabled a combination of the control groups for comparative purposes. The mean adhesion scores for the cut and scrape lesions for each of the barriers tested exceeded the adhesion scores for each of the respective internal controls in the majority of the groups studied (Table II). For the scrape lesions, most of the barriers tested had
Volume Number
143 7
significantly more adhesions when compared to the combined control groups (Table IIIA). For the cut lesions, only the peritoneum group had significantly more adhesions when compared to the controls. The Gelfoam paste and Surgicel groups did not have significantly more adhesions than the control groups for either type of induced lesion. The adhesion score for all barriers combined compared to the adhesion score for the combined control groups (cut and scrape lesions) had a highly significant increase in adhesions (Table IIIA). The mean adhesion scores for the dextran 70treated groups were low (Table II). The five animals treated with 32% dextran 70 had the lowest mean adhesion scores (scrape 0.55 f 0.16; cut 1.56 t 0.55) of all groups, including the controls, but this was not significantly different from the external or combined controls. Likewise, the adhesion score for the dextran 70 groups combined was not significantly different from the score for the external and internal controls combined (Table IIIA). The adhesion score (cut and scrape lesions) for the combined 6% and 32% dextran 70-treated animals was significantly less than the adhesion scores for the groups treated with Gelfilm, omentum, peritoneum, and Silastic (Table IIIB). Gelfoam paste had more adhesions than the combined dextran 70 animals only for the cut lesions; the amnion and Surgicel groups were not significantly different from the combined dextran 70 animals. The combined barrier adhesion score was significantly increased over the combined dextran 70 adhesion score with a p I 0.001 (Table IIIB). The barrier methods tested were often associated with an increased number of adhesions in many animals. The barriers themselves were frequently observed to be the focus of an inflammatory response.
Comment The results of this study indicate that generally the use of both natural and synthetic barriers promoted the formation of adhesions. Only the use of Surgicel was not significantly inferior to the controls and dextran 70-treated animals in regard to adhesions; but like most of the other barriers, it also, had a higher mean adhesion score than the controls. The natural barriers, such as omentum, peritoneum, and amnion, are essentially avascular grafts and eventually undergo necrosis. These changes promote deposition of fibrin and inflammation and theoretically would tend to promote adhesions, in agreement with our findings. Previous studies of natural barrier methods have generally been confined to evaluating free grafts of omenturn used more as a plug after bowel injuries83 I63I7 The
Prevention
of postoperative
pelvic
adhesions
833
authors of those studies invariably commented on the large amount of adhesions after the use of free omental grafts. Amnion was significantly inferior to controls when scrape lesions were compared and had higher mean adhesion scores than its internal controls. A previous study concluded that allografts of amnion were efficacious in inhibiting the formation of adhesions after induced bowel injuries in rabbits.‘O The discrepancy between these results and our own may be explained by the use of bowel as opposed to uterine injuries, the use of antibiotics in the first study, and, perhaps, the inability to always identify and place the mesenchyme surface of the amnion toward the injured area in this study. The synthetic barriers tested also promoted the formation of adhesions. Barriers, such as Gelfilm, Silastic, and Gelfoam, will attract an inflammatory response as a part of the degradation process. All synthetic barriers also have the potential to act as foreign bodies. These properties of synthetic barriers would theoretically promote the formation of adhesions, which is in agreement with our findings. It is interesting that the two synthetic barriers (Gelfoam and Surgicel) that were associated with less formation of adhesions than the other barriers were mixed or saturated with 32% dextran 70 prior to their application. Previously, Gelfoam paste had been found to be efficacious in inhibiting the formation of adhesions in pigs.rs Perhaps the differences in induced lesions and in the animal models studied and the use of antibiotics in the previous study would account for the discrepancy in results. Surgicel was found to be effective in preventing the formation of adhesions after induced injuries to the cecum in rats, but again the organ, animal model, and the method of inducing lesions were different from those in the present study.rg The intraperitoneal administration of 32% dextran 70 has been found to be effective in inhibiting the formation of adhesions in recent studies performed in rabbit93 ‘O-** and monkeys.7 It is postulated that bathing the pelvic organs with 32% dextran 70 solution prevents the postoperative agglutination of the fibrinrich injured surfaces and thereby prevents the formation of adhesions. The dextran 70 treatment in this study was clearly superior to barrier methods in preventing the formation of adhesions. But in contrast to previous studies, this study found no difference in the formation of adhesions when the 32% dextran 70 solution was compared to controls. It should be noted, however, that the rabbits treated with 32% dextran 70 had the lowest mean adhesion score of all the groups tested. The four previous studies in a rabbit model that concluded that 32% dextran 70 was effective in pre-
834
Soules
August 1, 1982 Am. J. Obstet. Gynecol.
et al.
venting the formation of pelvic more differences in methodology the current study.6, 2o-22 The conclusion drawn is that and synthetic barrier methods in preventing the formation of
adhesions had one or from each other and the natural (avascular) tested are not effective adhesions and actually
appear to promote the formation of adhesions in most instances. The postoperative administration of intraperitoneal 32% dextran 70 is clearly the leading candidate, on the basis of previous studies, as an effective agent to prevent the initial formation and recurrence of pelvic adhesions.
REFERENCES
1. Behrman, J., and Kistner, R. W.: Progress in Infertility, ed. 2, Boston, 1975, Little, Brown & Company, p. 230. 2. Seitz, H., Schenker, J. G., Epstein, S., and Garcia, C.-R.: Postoperative intraperitoneal adhesions: A double-blind assessment of their prevention in the monkey, Fertil. Steril. 24:935, 1973. 3. Ellis, H.: The cause and prevention of postoperative intraperitoneal adhesions, Surg. Gynecol. Obstet. 133:497, 1971. 4. Gilmore, 0. J. A., Reid, C., Houang, E. T., and Shaw, E. J.: Prophylactic intraperitoneal povidone-iodine in alimentary tract surgery, Am. J. Surg. 135:156, 1978. 5. Kaput-, B. M. L., Gulati, S. M., and Talwor, J. R.: Prevention of reformation of peritoneal adhesions, Arch. Surg. 105:761. 1972. 6. Holtz, d., and Baker, E.: Inhibition of peritoneal adhesions. Reformation after lysis with 32% Dextran 70, Fertil. Steril. 34:394, 1980. 7. DiZerega, G. S., and Hodgen, G. D.: Prevention of postoperative tubal adhesions, AM. J. OBSTET. GYNECOL. 136:173, 1980. 8. Davis, C. B.: Free transplantation of the omentum, JAMA 68:705, 1917. 9. Ellis, H,., Harrison, W., and Hugh, T. B.: The healing of peritoneum under normal and pathological conditions, Br. J. Surg. 52:471, 1965. 10. Trelford-Sauder. M., Dawe, E. I., and Trelford, I. D.: Use of allograft amniotic membrane for control of&a abdominal adhesions. I. Med. 9:273. 1978. 11. Behrman, J., and Kistker, R. W.: Progress in Infertility, ed. 2, Boston, 1975, Little, Brown and Company, p. 360. 12. Ridley, R. H., editor: Gynecologic Surgery. Errors,
13. 14. 15. 16. 17.
18.
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Safeguards Salvage, ed. 1, Baltimore, 1974, Williams & Wilkins, p. 28. Tovell, H. M. M., and Dank, L. D.: Gynecologic Operations, ed. 1, Hagerstown, Maryland, 1978, Harper & Row, p. 76. Patton, G. W., and Kistner, R. W., editors: Atlas of Infertility Surgery, Boston, 1975, Little, Brown and Company, p. 103. Siegel, S.: Nonparametric Statistics for the Behavioral Sciences, New York, 1956, McGraw-Hill Book Company, pp. 120-121. Pettet, J. R., Judd, E. S., and Woolner, L. B.: Free omental grafts applied to intestinal anastomoses, Arch. Surg. 72:925, 1956. Finton, W. L., and Peet, M. M.: An experimental study of the use of detached omental grafts in intestinal surgery, Surg. Gynecol. Obstet. 29:281, 1919. Luengo, J., and Van Hall, E. V.: Prevention of peritoneal adhesions by the combined use of Spongostan and 32% dextran 70: An experimental study in pigs, Fertil. Steril. 29:447. 1978. Larsson, B., Nisell, H., and Granberg, I.: Surgicel-an absorbable hemostatic material-in prevention of peritoneal adhesions in rats, Acta Chit-. Stand. 144:375, 1978. Holtz, G., Baker, E., and Tsai, C.: Effect of 32% dextran 70 on peritoneal adhesion formation and re-formation after lysis, Fertil. Steril. 33:660, 1980. Neuwirth, R. S., and Khalaf, S. M.: Effect of 32% dextran 70 on peritoneal adhesion formation, AM. J. OBSTET. GYNECOL. 121:420, 1975. Utian, W. H., Goldfarb, J. M., and Starks, G. C.: Role of dextran 70 in microtubal surgery, Fertil. Steril. 31:79, 1979.