Large bowel anastomoses. I. The healing process and sutured anastomoses. A review

Effect of Paclitaxel-based Hyperthermic Intraperitoneal Chemotherapy (HIPEC) on colonic anastomosis in a rat model

BACKGROUND

Paclitaxel has been used frequently for Hyperthermic Intraperitoneal Chemotherapy (HIPEC) for ovarian carcinomatosis. Cytoreductive surgery and HIPEC are associated with high rates of morbidity being anastomotic dehiscence one of the most frequent. The objective of this study is to quantify the effect of Paclitaxel-based HIPEC on colonic anastomosis in an experimental rat model.

METHODS

After left colon resection and anastomosis, animals were randomized into four groups: Controls (C); Hyperthermia (H); Normothermic Intraperitoneal Paclitaxel (CP) and Paclitaxel-based HIPEC (HP). On postoperative day four, animals' peritoneal cavities were examined macroscopically, colon anastomosis burst pressures measured and specimens analyzed histologically.

RESULTS

Thirty-nine animals were randomized and 36 were included in the analysis. H group presented the highest burst pressure 105.11 ± 22.9 mmHg, which was 27% higher than C (77.89 ± 27.6 mmHg). On the other hand, HP presented the lowest burst pressure 64 ± 26 mmHg, 16% lower than C group and 39% lower than H, being this latter difference statistically significant (p = 0.004). There were no significant differences regarding weight loss, adhesion scores, perianastomotic abscesses and histological findings (inflammation, fibroblasts, neoangiogenesis, and collagen among groups).

CONCLUSION

Strength of colonic anastomosis was improved by isolated hyperthermia and negatively affected by Paclitaxel-based HIPEC.

A novel and simple method using a transanal intestinal long tube for protecting intestinal anastomosis and decompressing the small bowel

PURPOSE

I introduce the use of transanal intestinal long tube (TILT) using nasogastric tube. TILT passes from anus to the anastomosis, helping to decompress a dilated bowel loop.

METHODS

TILT procedure was limited to those patients predicting a severe luminal size discrepancy after intestinal anastomosis, and who had postoperative prolonged ileus. We retrospectively reviewed the medical records of 10 infants (7 male an 3 female patients) who were treated using the TILT procedure between 2012 and 2016.

RESULTS

Median gestational age was 27⁺⁵ weeks and birth weight was 940 g. The first operation was done at a median of 4.5 days after birth due to necrotizing enterocolitis perforation (4 cases), isolated intestinal perforation (3 cases), meconium related ileus (1 case), congenital ileal volvulus (1 case), and ileal atresia (1 case). Nine cases of ileostomy closure were planned at a median of 130.5 days with a body weight of 3,060 g. For the ileal atresia case, TILT procedure without additional small bowel resection was performed to treat postoperative prolonged ileus. Nine out of ten were well functioned and defecation via anus was observed in a median of 4.5 days. Milk feeding began at a median of 6 days and the long intestinal tube was removed in a median of 14.5 days.

CONCLUSION

I suggested that TILT procedure could be a noninvasive operative option, predicting of size mismatched anastomosis causing prolonged ileus. Passive drainage of proximal intestinal contents might be helpful for decompress endoluminal pressure during the time of anastomosis healing with bowel movement recovery.

Circular anastomotic experimental fibrin sealant protection in deep colorectal anastomosis in pigs in a randomized 9-day survival study

PURPOSE

The reported rate of clinically apparent anastomotic leakage (AL) in a low anterior resection of the rectum (LAR) (≤7 cm from the anal verge) using a circular double-stapled anastomosis (CDSA) without defunctioning stoma is up to 37.5 %. Since AL may result in life-threatening peritonitis, sepsis, and multiple organ failure, LAR and CDSA are regularly combined with defunctioning stoma. Accordingly, we now evaluated whether LAR and CDSA without defunctioning stoma but with extraluminal anastomotic application of an experimental fibrin sealant reduce the AL rate. This might prevent humans from defunctioning stoma increasing quality of life and decreasing surgical costs.

METHODS

Forty 8-week-old pigs underwent LAR and CDSA in an end-to-end technique (descendo-rectostomy). Animals were randomized into a therapy and control group (gr.). The therapy gr. (n = 20) received an additional extraluminal circular application of an experimental fibrin sealant to the anastomosis. The objective was to assess the incidence of clinically apparent and non-clinically apparent leakage through the ninth postoperative day. Double-contrast barium CT radiographs of the colorectal region were performed on the ninth postoperative day or earlier, in case there were clinical signs of AL. All remaining animals were sacrificed on the ninth postoperative day and the anastomotic region was histopathologically analyzed. In case of earlier diagnosed AL, animals were sacrificed immediately. Blood samples were taken for complete blood count, chemistry, and coagulation profile prior to surgery and on the first, third, fifth, seventh, and ninth postoperative day.

RESULTS

A circular extraluminal anastomotic application of an experimental fibrin protection decreased the rate of clinically and non-clinically apparent AL from 20 % (n = 4) in the control group to 5 % (n = 1) in the treatment group. Ulcerations were also observed in both gr. (control gr.-5 animals, therapy gr. -3 animals). All animals with AL showed necrosis surrounding the hole at the anastomoses. Three additional animals had a full wall defect at the anastomotic region that was blocked by the experimental fibrin sealant. The fibrin sealant was present at necropsy in all treated animals.

CONCLUSION

Circular anastomotic protection with the experimental fibrin sealant blocked anastomotic full wall defects, preventing peritonitis and significantly reducing the AL rate from 25 to 5 %.

The effects of hyperbaric oxygen therapy on experimental colon anastomosis after preoperative chemoradiotherapy

The aim of the present study was to investigate the effect of hyperbaric oxygen therapy (HBOT) on colon anastomosis after chemoradiotherapy (CRT). Sixty female Wistar-Albino rats were divided into 5 groups and underwent left colon resection and end-to-end anastomosis. CRT simulation was performed on 2 sham groups before the anastomosis, and 1 of these groups was administered additional postoperative HBOT. Two groups were administered CRT before the anastomosis, and 1 of them received additional postoperative HBOT. On postoperative day 5, all groups underwent relaparotomy; burst pressure was measured and samples were obtained for histopathologic and biochemical analysis. There was a significant weight loss in the CRT groups and postoperative HBOT had an improving effect. Significantly decreased burst pressure values increased up to the levels of the controls after HBOT. Hydroxyproline levels were elevated in all groups compared to the control group. Hydroxyproline levels decreased with HBOT after CRT. No significant difference was observed between the groups regarding fibrosis formation at the anastomosis site. However, regression was observed in fibrosis in the group receiving HBOT after CRT. Preoperative CRT affected anastomosis and wound healing unfavorably. These unfavorable effects were alleviated by postoperative HBOT. HBOT improved the mechanical and biochemical parameters of colon anastomosis in rats.

A new anastomotic leakage model in circular double stapled colorectal anastomosis after low anterior rectum resection in pigs

BACKGROUND

A high incidence of anastomotic leakage (37.5%) is reported after low anterior rectal resection (LAR) and circular double-stapled anastomosis without protective ileostoma. Since the pathomechanism of anastomosis leakage is still unclear, a suitable animal model would be most desirable.

METHODS

The objective was to assess the incidence of clinically apparent and inapparent leakage after LAR in pigs (n = 20). Endpoints were radiological, clinical, macroscopic, and histologic proof of anastomotic leakage on the 9th postoperative day. Integrity of anastomosis was assessed by double-contrast barium examination on 9th postoperative day. Animals were sacrificed and anastomoses were resected for histopathological investigation. In case of earlier clinical apparent anastomotic leakage, radiologic double-contrast barium was performed immediately.

RESULTS

LAR with a circular double-stapled anastomosis without protective ileostoma was performed in 20 pigs (m:f = 8:12). Length of resection was 10-20 cm, anastomosis was performed 7 cm ab ano. Five animals (25%) developed clinical apparent anastomotic leakage (no appetite, fever, inactivity, tachypnea, discomfort, pain) between the 6th (n = 1) and 9th (n = 4) postoperative day, proven by double-contrast barium radiographs. Additionally in 1 animal clinical inapparent anastomotic insufficiency was observed radiologically. Total rate of leakage was 30% (n = 6). These results were confirmed by leucocytosis, low potassium levels, in two cases high ALT and AST and local peritonitis in all cases.

CONCLUSION

Including one additional case of clinical inapparent leakage, total rate of anastomotic leakage was 30% (6/20). Thus we managed to establish a new experimental model of anastomotic leakage after low rectal resection comparable to the human situation.

Use of a transanal drainage tube for prevention of anastomotic leakage and bleeding after anterior resection for rectal cancer

BACKGROUND

The aim of the present study was to investigate the usefulness of the transanal drainage tube for prevention of anastomotic leakage and bleeding after anterior resection for rectal cancer.

METHODS

Between January 2007 and May 2011 a nonrandomized prospective study of patients undergoing anterior resection for rectal cancer was done. The patients were divided into the transanal drainage tube (TDT) and non-transanal drainage tube (NTDT) groups according to whether the transanal drainage tube was used in the operation. Clinical characteristics and postoperative complications were compared between the TDT and NTDT groups.

RESULTS

The study included 81 patients in the TDT group and 77 patients in the NTDT group. In the TDT group, anastomotic leakage occurred in 2 patients and no anastomotic bleeding occurred. In the NTDT group, anastomotic leakage occurred in 7 patients and anastomotic bleeding occurred in 2 patients. The TDT group had significantly fewer anastomotic complications compared with the NTDT group (2.5 vs 11.7 %; P = 0.029). Furthermore, the TDT group showed an obvious reduction in the rate of anastomotic leakage and anastomotic bleeding compared with the NTDT group (2.5 vs 7.8 % and 0.0 vs 2.6 %), but because the number of cases is relatively small, the difference did not reach statistical significance (P = 0.160 and P = 0.236).

CONCLUSIONS

The use of a transanal drainage tube in anterior resection for rectal cancer may be a simple, safe, and effective means of preventing or reducing the occurrence of anastomotic leakage and bleeding. A larger-scale single or multi-center prospective randomized study or a meta-analysis including similar studies is necessary for further elucidation of this issue.

Techniques for colorectal anastomosis

Colorectal anastomotic leak remains one of the most feared post-operative complications, particularly after anterior resection of the rectum with, the shift from abdomino-peritoneal resections to total mesorectal excision and primary anastomosis. The literature fails to demonstrate superiority of stapled over hand-sewn techniques in colorectal anastomosis, regardless of the level of anastomosis, although a high stricture rate was noted in the former technique. Thus, improvements in safety aspects of anastomosis and alternatives to hand-sewn and stapled techniques are being sought. Here, we review alternative anastomotic techniques used to fashion bowel anastomosis. Compression anastomosis using compression anastomotic clips, endoluminal compression anastomotic rings, AKA-2, biofragmental anastomotic rings, or Magnamosis all involve the concept of creating a sutureless end-to-end anastomosis by compressing two bowel ends together, leading to a simultaneous necrosis and healing process that joins the two lumens. Staple line reinforcement is a new approach that reduce the drawbacks of staplers used in colorectal practice, i.e. leakage, bleeding, misfiring, and inadequate tissue approximation. Various non-absorbable, semi or fully absorbable materials are now available. Two other techniques can provide alternative anastomotic support to the suture line: a colorectal drain and a polyester stent, which can be utilized in ultra-low rectal excision and can negate the formation of a defunctioning stoma. Doxycycline coated sutures have been used to overcome the post-operative weakness in anastomosis secondary to rapid matrix degradation mediated by matrix metalloproteinase. Another novel technique, the electric welding system, showed promising results in construction of a safe, neat, smooth sutureless bowel anastomosis. Various anastomotic techniques have been shown to be comparable to the standard techniques of suturing and stapling. However, most of these alternatives need to be accepted and optimized for future use.

Anastomoses of the lower gastrointestinal tract

Patients with gastrointestinal anastomoses are treated by physicians of multiple specialties, including gastroenterologists, radiologists and surgeons. This Review provides an overview of the surgical principles and techniques involved in the creation of lower intestinal anastomoses, including some of the mechanisms of healing. Anatomical configurations of small and large bowel anastomoses are illustrated. Stapled, hand-sewn, and sutureless anstomotic techniques are also discussed. Laparoscopy has revolutionized our approach to surgery of the gastrointestinal tract and we describe some of the current and future minimally invasive techniques for creating anastomoses. The article also highlights principles important in minimizing potential short-term and long-term complications such as anastomotic leaks and strictures. Common risk factors for dehiscence include poor nutrition, immunosuppression, microvascular disease, obesity and technical errors. An evidence-based review of perioperative and postoperative management of intestinal anastomoses is provided to help optimize patient care. The routine use of nasogastric tubes and mechanical bowel preparation has no documented benefits and could contribute to postoperative complications. Upcoming strategies that might prove useful to reinforce anastomoses are also reviewed.

Effect of thalidomide on the healing of colonic anastomosis, in rats

PURPOSE: Thalidomide, because of its anti-inflammatory properties, as re-emerged as an option for the treatment of Crohn's disease refractory to standard therapy. We studied the effect of thalidomide on the healing of colonic anastomosis. METHODS: Sixty male rats (Rattus norvegicus), were divided into 3 groups of 20 animals each, respectively receiving 0.5 or 1.0 mg/kg thalidomide by the oral route for 7 days, or saline solution (control). All animals were submitted to continuous end-to-end anastomosis with 6-0 Prolene sutures. After sacrifice the anastomoses were analyzed macroscopically and submitted to determination of hydroxyproline, to histology and to immunohistochemistry for metalloproteinase 1, metalloproteinase 1 inhibitor and vascular endothelial growth factor (VEGF). RESULTS: Statistical analysis of the data showed no significant difference in macroscopic aspect or hydroxyproline determination (p= 0.5403). In the immunohistochemical analysis, the following p values were obtained: p = 0.5817 for VEGF, p = 0.1854 for metalloproteinase 1, and p = 0.0023 for metalloproteinase 1 inhibitor, with this last value being considered statistically significant. CONCLUSION: We conclude that thalidomide influenced collagen maturation. There was a stronger action of metalloproteinases, possibly indicating a negative tendency for the healing process.

Effects of platelet rich plasma on colonic anastomosis

PURPOSE

To investigate the effect of platelet-rich plasma (PRP) on tissue maturation and wound healing in experimental colonic anastomosis.

MATERIALS AND METHODS

Thirty Sprague Dawley rats were divided into three groups of 10 rats each. Group I (control group) was subjected to colon anastomosis only. Group II (PRP group) was subjected to colon anastomosis and topical PRP was applied. Group III (Bioglue group) was subjected to colon anastomosis and topical tissue sealant was applied (Bioglue; Cryolife, Kennesaw, GA). The rats were sacrificed on postoperative day 7, and the bursting pressure of the anastomosis and tissue hydroxyproline levels were measured; histopathological changes on the anastomosis line were also examined.

RESULTS

The bursting pressure was statistically higher in the PRP group than in the control and Bioglue groups (P < 0.05). The hydroxyproline levels were also statistically higher in the PRP group than in the control and Bioglue groups (P < 0.05). Histopathologically, there was less inflammatory cell infiltration, intensive fibroblast development, and rich collagen production in the PRP group.

CONCLUSION

PRP may be used in colon anastomosis, especially in patients with impaired wound healing, to obtain a better anastomotic strength.

The effect of remote ischemic preconditioning on healing of colonic anastomoses

BACKGROUND

We aimed to investigate the potential protective effect of remote ischemic preconditioning (IPC) on delayed colonic anastomotic healing induced by remote ischemia and reperfusion (I/R) injury.

MATERIALS AND METHODS

Forty male Wistar rats were randomly assigned into four groups, each consisting of 10 rats: the control group (C), the remote I/R group [I/R, 40 min of superior mesenteric artery (SMA) occlusion], the preconditioned I/R group (IPC, two cycles of 5 min temporary occlusion of SMA before an ischemic insult of 40 min), and the preconditioned group (PC, two cycles of 5 min temporary occlusion of SMA). Colonic anastomosis was performed immediately after the ischemic insult. Anastomotic healing was assessed on postoperative day 7 by determining anastomotic bursting pressure (ABP), tissue hydroxyproline content, histopathological examination, malondialdehyde (MDA), and nitric oxide levels.

RESULTS

Remote I/R injury resulted with significant impairment in anastomotic healing in terms of mean ABP (P = 0.004), hydroxyproline content (P = 0.002), histopathological healing score (P = 0.001), nitric oxide level (P = 0.010), and MDA levels (P = 0.0001) when compared with the control group, but remote IPC did not improve all above mentioned parameters (P = NS for all), except MDA level (P = 0.011) when compared with I/R group. PC alone impaired the ABP (P = 0.0001), but it did not significantly change the other parameters measured (P = NS).

CONCLUSIONS

The results of this study showed that remote IPC did not prevent I/R-induced delaying in colonic anastomotic healing.

Hyperthermic intraperitoneal chemoperfusion (HIPEC) decrease wound strength of colonic anastomosis in a rat model

BACKGROUND AND AIMS

There is controversy about the effect of the influence of hyperthermia and chemotherapeutic agents on the healing of intestinal anastomosis. The effects of hyperthermic intraperitoneal chemoperfusion (HIPEC) of wound healing after colonic anastomosis were investigated in a rat model.

MATERIALS AND METHODS

Thirty-six Wag/Rija rats were randomized into three groups of 12 animals each: group I: control (only colonic anastomosis was performed) (n = 12); group II: HIPEC (mitomycin C in a concentration of 20 mg/m(2) (n = 12) colonic anastomosis was performed before HIPEC; group III: HIPEC (mitomycin C in a concentration of 20 mg/m(2) (n = 12) colonic anastomosis was performed after HIPEC. Bursting pressure and bursting sites were recorded 4 and 10 days after intervention. Collagen deposits, inflammation and foreign body reactions were evaluated.

RESULTS

Lower bursting pressure and lost of collagen were found in both HIPEC groups and compared with the control group. There was almost no difference between both HIPEC groups. They were noted overwhelmingly at the anastomosis in the HIPEC group. The degree of collagen accumulation was well-correlated with bursting pressure.

CONCLUSION

These results have shown that hyperthermic intraperitoneal chemoperfusion (HIPEC) impairs wound healing in colonic anastomosis in rats.

Comparative study of the hyperbaric hyperoxygenation in ischemic colonic loops in rats

PURPOSE: To analyze and to evaluate the effect of the hyperbaric hyperoxygenation in the mechanical resistance of ischemic colon of rats. METHODS: Eighty rats, distributed in four groups of 20 animals in each one, were used. In group 1 (G1), the control group, ischemia was not caused. Group 2 was submitted to the lesser degree of ischemia. Group 3 was submitted to the intermediate degree of ischemia. In group 4, a bigger degree of intestinal ischemia was provoked. Each group was divided in two sub-groups of ten animals each: with hyperbaric chamber (CC) and without hyperbaric chamber (SC). The animals of the four CC subgroups were placed in an experimental hyperbaric chamber in order to inhale oxygen at 100%, at two Absolute Atmospheres, for 120 minutes, for a four-day consecutive period. The animals of the four SC subgroups were kept in environment air during the five days of the experiment. All animals have been submitted to the mechanical study of the intestinal loop by the pressure test of the rupture by liquid distension. The euthanasia occurred in the fifth post-operative day. RESULTS: Considering the ischemia factor, the four groups were different among them (p=0.0001). There was no statistical difference between subgroups CC and SC (p=0.3461). CONCLUSION: The hyperbaric oxygen-therapy did not present improvement on the induced ischemia in rats upright colic loop.

Preoperative and postoperative administration of hyperbaric oxygen improves biochemical and mechanical parameters on ischemic and normal colonic anastomoses

Colonic anastomotic leaks are a major postoperative complication, causing increased mortality and morbidity. Tissue ischemia is one of the most important factors that disrupt anastomotic healing. It is possible to reverse inadequate tissue oxygenation by using increased atmospheric pressure and hyperoxia, which are obtained from hyperbaric oxygen treatment (HBO). Our aim was to investigate the effects of preoperative and postoperative HBO treatment on normal and ischemic colonic anastomoses in rats. Eighty male Wistar Albino rats, weighing between 180 and 240 g, were divided into 8 equal groups. A 1-cm segment of left colon was resected 3 cm proximal to the peritoneal reflection in all groups and colonic anastomosis was performed. In groups 2, 4, 6 and 8, colonic ischemia was established by ligating 2 cm of mesocolon on either side of the anastomosis. Control groups (1 and 2) received no HBO. HBO treatment was given preoperatively in groups 3 and 4, postoperatively in groups 5 and 6, and both preoperatively and postoperatively in groups 7 and 8. HBO treatment was applied for 2 days in the preoperative period and 4 days in the postoperative period. Relaparotomy was performed on postoperative day 5 and a perianastomotic colon segment 2 cm in length was excised for detection of biochemical and mechanical parameters of anastomotic healing and histopathological evaluation. HBO treatment increased tissue hydroxyproline levels in all groups, and this difference was significant in normal anastomosis groups receiving preoperative HBO compared to controls (p = .013 for group 1 vs. group 3; p = .023 for group 1 vs. group 5). This improvement was more evident in ischemic and normal groups treated by administration of combined pre- and postoperative HBO (p = .021 and p = .013). HBO treatment also increased the mean bursting pressure values in all groups, and again, a statistically significant increase was noted in the ischemic groups compared to controls (p = .002 for group 2 vs. group 6; p = .001 for group 2 vs. group 8). Histopathological evaluation of anastomotic line fibrosis was not found to show significant differences between the groups. Adequate tissue oxygenation is the main factor in wound and anastomosis healing. HBO treatment has a positive effect on biochemical and mechanical parameters of ischemic and normal colon anastomoses in rats. It is possible to see this effect more clearly with combined HBO treatment applied before and after ischemic anastomosis.

Anastomotic disruption after large bowel resection

Anastomotic disruption is a feared and serious complication of colon surgery. Decades of research have identified factors favoring successful healing of anastomoses as well as risk factors for anastomotic disruption. However, some factors, such as the role of mechanical bowel preparation, remain controversial. Despite proper caution and excellent surgical technique, some anastomotic leaks are inevitable. The rapid identification of anastomotic leaks and the timely treatment in these cases are paramount.

Effect of hypercholesterolemia on experimental colonic anastomotic wound healing in rats

AIM: To evaluate the mechanical and biochemical parameters of colonic anastomotic healing in hypercholesterolemic rats.

METHODS: Sixty rats were divided into two groups of 30 each according to their dietary regimens. The test group was fed with a high cholesterol-containing diet for two months while the control group had standard diet. These two groups were further divided into three subgroups consisting of ten rats each. After hypercholesterolemia was established, left colon resection and anastomosis were performed in both groups and samples from liver and abdominal aorta were taken to evaluate the systemic effects of hypercholesterolemia. Anastomotic wound healing, blow-out pressures and tissue hydroxyproline levels were evaluated.

RESULTS: The test group had a significant weight gain in two months. Microscopic examination of the abdominal aorta revealed no atherosclerotic change in none of the groups, but liver tissue specimens showed significant steatosis in the test group. Tissue hydroxyproline levels and anastomotic blow-out pressures were significantly lower in the test group than in the controls.

CONCLUSION: Hypercholesterolemia not only increases hydroxyproline levels and blow-out pressures but also worsens anastomotic wound healing.

Efeito de aderências dirigidas em anastomoses cólicas isquêmicas em ratos

OBJETIVO: Avaliar o efeito das aderências dirigidas sobre a resistência mecânica de anastomoses realizadas em cólon isquêmico através da aplicação dos testes Resistência à Pressão de Explosão e Resistência à Força de Tração. MÉTODOS: Quarenta ratos foram distribuídos igualmente em dois grupos. O Grupo 1 era constituído de vinte animais em que as anastomoses cólicas isquêmicas foram recobertas por uma película de polivinilcloreto (P.V.C.) para impedir a formação de aderências sobre as linhas de sutura e o Grupo 2 era constituído por 20 animais em que as anastomoses cólicas isquêmicas foram recobertas pela gordura epididimal, de forma a constituir uma aderência dirigida sobre a linha de sutura, sendo ainda recobertas por uma película de P.V.C. para impedir a formação de outras aderências. RESULTADOS: A média da Pressão de Ruptura à Distensão por Líquidos da anastomose foi de 10 mmHg no grupo sem aderência e de 55,2 mmHg no grupo com aderência (p < 0,05). A média da Força de Ruptura à Tração das anastomoses foi de 142,5 gf no grupo sem aderências e de 262 gf no grupo com aderência (p < 0,05). CONCLUSÃO: As aderências mostraram ser benéficas, elevando a resistência intrínseca das anastomoses tanto na Resistência à Distensão por Líquido quanto na Resistência à Força de Tração.

Estudo comparativo da hiperoxigenação hiperbárica em alças cólicas isquêmicas em ratos

OBJETIVO: Analisar e avaliar os efeitos da hiperoxigenação hiperbárica na resistência mecânica do cólon isquêmico de ratos. MÉTODOS: Foram utilizados 80 ratos distribuídos em quatro grupos de 20 animais. No grupo 1, grupo controle, não se provocou isquemia. O grupo 2 foi submetido ao grau menor de isquemia. O grupo 3 foi submetido ao grau intermediário de isquemia. No grupo 4, provocou-se grau maior de isquemia intestinal. Cada grupo foi dividido em dois subgrupos de dez animais cada: com câmara hiperbárica (CC) e sem câmara hiperbárica (SC). Os animais dos quatro subgrupos CC foram colocados em uma câmara hiperbárica experimental para inalarem oxigênio a 100%, a duas atmosferas absolutas, durante 120 minutos, por quatro dias consecutivos. Os animais dos quatro subgrupos SC foram mantidos somente em ar ambiente. Todos animais foram submetidos ao estudo mecânico da alça intestinal pelo teste de pressão de ruptura pela distensão por líquido. A eutanásia ocorreu no quinto dia pós-operatório. RESULTADOS: Os quatro grupos são diferentes entre si considerando o fator isquemia (p= 0,0001). Não houve diferença estatística entre os subgrupos CC e SC (p= 0,3461). CONCLUSÃO: A oxigenoterapia hiperbárica não apresentou melhora sobre a isquemia induzida em alça cólica íntegra de ratos.

Effects of trapidil on the healing of colonic anastomoses in an experimental rat model

BACKGROUND

Trapidil has various properties including vasodilatation, inhibition of lipid peroxidation and platelet aggregation as well as, and reduction of, the inflammatory response to injury. The aim of the present study was to investigate the effects of trapidil on dexamethasone-impaired colonic anastomotic healing in an experimental rat model.

METHODS

Twenty-four Wistar rats underwent colonic transsection and primary anastomosis. Rats were divided into four groups of six: group 1 (G1), control; group 2 (G2) trapidil, 8 mg/kg per day intravenously; group 3 (G3) dexamethasone, 0.1 mg/kg per day intramuscularly; and group 4 (G4) dexamethasone 0.1 mg/kg intramuscularly and trapidil 8 mg/kg intravenously per day, for 1 week. Anastomotic bursting pressure, hydroxyproline level, histopathological grading, malondialdehyde and nitrite/nitrate levels were determined.

RESULTS

Dexamethasone-impaired anastomotic healing was found to be improved by trapidil administration in terms of anastomotic bursting pressure and hydroxyproline content (P = 0.026, and P = 0.017). In addition, histopathological examination revealed an increase in fibroblast proliferation and collagen deposition (P = 0.004, and P = 0.015) and a decrease in leucocyte infiltration (P = 0.004). Moreover, serum nitrite/nitrate and malondialdehyde levels decreased when G3 was compared to G4 (P < 0.001, P = 0.38).

CONCLUSIONS

Trapidil may improve the dexamethasone-impaired anastomotic healing due to its preventive effects on inflammatory response and lipid peroxidation in rats.

Edema quantification by computerized morphometry as an evaluation parameter for the resistance of colon anastomoses

PURPOSE: This work had the objective of verifying the validity of using computerized morphometry as a method of quantitative analysis of the interference of edema in scar formation following colon anastomosis. METHODS: Forty-five adult female Wistar rats were utilized, divided into three groups of 15 animals according to whether sacrifice was performed on the first, second or seventh postoperative day. Each group was subdivided into a main group consisting of 10 animals, and a control group consisting of five animals. In the main group, in addition to the quantitative computerized morphometric analysis of the edema in the submucosal layer, the resistance of the colon anastomosis to bursting strength was verified. In the control group, edema quantification was studied alone. RESULTS: The results found via the computerized morphometry method showed that there is a 7% decrease in the presence of edema during the first postoperative week. They confirmed that there is an inverse statistically significant relationship (p< 0.001) between edema presence and the resistance of the anastomosis to bursting strength. CONCLUSION: The use of computerized morphometry is a reliable, fast, objective and low-cost methodology for the quantification of edema in colon anastomoses.

Anastomotic leakage after low rectal stapler anastomosis: significance of intraoperative anastomotic testing

AIMS

One of the most significant surgical complications following rectal resection with primary anastomosis is anastomotic leakage. The aim of this study was to evaluate the benefit of intraoperative anastomotic testing of stapled anastomoses and the impact on leakage rate.

METHODS

Between 1987 and 2000, 1360 consecutive rectal resections for carcinoma were performed. In 933 operations rectal resection was completed with either stapled (n=788), handsewn (n=80) or coloanal (n=65) anastomosis. Since 1995 we introduced intraoperative anastomotic testing, routinely. Between 1995 and 2000, 296 patients were treated with stapled anastomosis following rectal resection. Different variables influencing anastomotic leakage were evaluated.

RESULTS

Between 1987 and 2000, 68 of 933 patients treated by resection and anastomosis developed a clinically significant anastomotic leak (7.3%) where as between 1995 and 2000 the leakage rate was 9.8% of all patients with stapled anastomosis. There was an increase in resection rate from 62 to 72%. Since 1995 we demonstrated either intraluminal bleeding or leakage in 18.1% of all stapled anastomoses by intraoperative anastomotic testing. The postoperative anastomotic leakage rate was equal in those patients with normal and abnormal findings of anastomotic testing even though 74% of all patients with irregular findings were treated by performing a protective stoma simultaneously. We found no significant risk factor for the development of anastomotic leakage.

CONCLUSION

We recommend a protective stoma with any anastomosis within the lower third of the rectum. Anastomoses within the middle and upper third of the rectum demonstrate a lower risk of anastomotic insufficiency and do not need a protective stoma, routinely.

End-on extramucosal single layer suture with double anchoring in the submucosa on rabbits

The techniques of gastrointestinal surgical sutures have been frequently focused in controversial publications. These ones concern not only anastomosis’ types but also about thread types and how to apply them. The values of the submucosa as layer of greatest resistence of the digestive tube was already known since the past century. The aim of this study is to avaluate the suture in an extramucosal single-layer suture with double anchoring of the submucosa, a technical detail not found in the searched literature. This experiment was carried out using 36 white,male adults New Zealand, rabbits divided into three groups which differed only regarding day of re-operation and euthanasia, as followed: group I ( 4 days), group II (7 days) and group III ( 15 days). Two transversal and parallel gastrotomies were perfomed in the same animal, one distal and other proximal, of with 4 cm extension each. In these gastrotomies two types of sutures were alternated : 1- End-on extramucosal single-layer suture and 2- End-on extramucosal single-layer suture, with double anchoring in the submucosa. Macroscopic and microscopic studies were perfomed on the suture line in both gastrotomies and in each period of euthanasia. Except for the serosa item whose results were similar for both sutures, statiscally, the extramucosal single-layer suture, with double anchoring of submucosa layer showed better macro and microscopic results than the extramucosal single-layer suture in group I (4 days). In the others periods of euthanasia (groups II and III), the statistical results were similar.

Intestinal anastomosis in children: a comparative study between two different techniques

PURPOSE

The aim of this study was to compare the incidence of surgical complications between two different surgical techniques for intestinal anastomosis in children.

METHODS

This was a clinically controlled, randomized study with blind follow-up from 18 to 36 months performed at the Reference Government Hospital in Mexico City. Eighty-six children required intestinal anastomosis, ages ranged between 1 month and 16 years, with emergency or elective surgery. Anastomoses of duodenum, rectum, with enteroplasty or protected with a proximal stoma were excluded. Two randomized groups were formed: (1) anastomosis with one layer of suture (Gambee stitches) and (2) with two layers of suture (first with Connel-Mayo stitches then with Lembert). Both groups were controlled in the principal variables without differences, and the follow-up concerning postoperative recovery was blind for the surgical team.

RESULTS

Forty-two cases in group 1 and 44 in group 2 were compared. Intestinal dehiscence was found in 5 of 86 (5.8%), two from group I and three from group II (P value, not significant). Surgical time for anastomosis with one layer was an average of 26 minutes versus 43 minutes with two layers (P<.001). There were no stenoses within the follow-up period.

CONCLUSIONS

This study proves that intestinal anastomosis with one layer of suture is as safe as anastomosis with two layers in children, and the time spent for completion of the procedure is significantly less with one plane of suture. For those reasons, it is the method of choice for intestinal anastomosis in children.

Temporal expression of TGF-beta1, EGF, and PDGF-BB in a model of colonic wound healing

BACKGROUND

Dehiscence of colonic anastomoses is a multifactorial phenomenon. One mechanism by which this can occur is a deficiency of colonic submucosal collagen. Peptide growth factors (PGFs) have been shown to play a role in the synthesis, deposition, and maturation of collagen. Specifically, in tissues other than the colon, the transforming growth factor-beta (TGF-beta1) gene has been shown to be temporally associated with expression of the procollagen gene. This study examines the temporal expression of the TGF-beta1, epidermal growth factor (EGF), and platelet-derived growth factor B (PDGF-BB) genes and their temporal relationship to the expression of the procollagen type 1 (PROC I) gene.

MATERIALS AND METHODS

Forty-eight Sprague-Dawley rats underwent transection of the descending colon with primary anastomosis. Perianastomotic colonic tissue was harvested on Day 0 and postoperative days 3, 5, 6, 7, and 14. Colonic tissue was analyzed using semiquantitative reverse transcriptase-polymerase chain reaction and primers specific for the TGF-beta1, EGF, and PDGF-B growth factors. Relative expression ratios of PGFs and PROC I genes were calculated versus a constitutive gene.

RESULTS

The data show that although all three of the PGFs genes were expressed in healing postoperative colonic tissue, only TGF-beta1 showed a significant increase in its level of expression versus a constitutive gene from a mean ratio of 0.4 +/- 0. 08 on Day 0 to a mean ratio of 1.9 +/- 0.27 on Day 7 (P < 0.0001 by ANOVA). The PROC I gene also showed a significant increase in expression (P < 0.001 by ANOVA) in the postoperative period which temporally correlated with the increase in the expression of the TGF-beta1 gene (r = 0.89, P < 0.05).

CONCLUSIONS

The temporal correlation between an increase in the gene expression of TGF-beta1 and PROC I is initial evidence that that TGF-beta1 plays a significant role in collagen metabolism in a healing colonic anastomosis.

The effects of hyperbaric oxygen on normal and ischemic colon anastomoses

BACKGROUND

Leakage from colonic anastomoses is a major complication causing increased mortality and morbidity, and ischemia is a well-known cause of this event. Inadequate tissue oxygenation could be reversed by using hyperbaric oxygen. This study was designed to investigate the effects of hyperbaric oxygen on the healing of ischemic and normal colon anastomoses in the rat model.

METHODS

Standardized left colon resection 3 cm above the peritoneal reflection and colonic anastomosis were performed in 40 Wistar rats divided into four groups. The control group (I) received no further treatment. To mimic ischemia, 2 cm mesocolon was ligated on either site of the anastomosis in group II and IV rats. Hyperbaric oxygen therapy was started immediately after surgery in group III and IV rats (therapeutic groups). All animals were sacrificed on the fourth postoperative day. After careful relaparotomy, in situ bursting pressure was measured. The hydroxyproline contents of the anastomotic segments in equal length were determined.

RESULTS

The hydroxyproline assay revealed that rats in group II with ischemic colonic anastomosis have significantly lower levels (P <0.05). The highest levels are in the group III rats with normal colonic anastomosis treated by hyperbaric oxygen (P <0.05). There was no significant difference in hydroxyproline levels between group II and group IV animals (P >0.05). Group III animals had significantly higher bursting pressures than any other group (P <0.05). Group II rats had lowest bursting pressures (P <0.05). Group IV animals had significantly higher levels than group II (P <0.05). Mean bursting pressure values both in groups III and IV and hydroxyproline levels in group III were significantly increased by hyperbaric oxygen therapy (P <0.05).

CONCLUSIONS

Ischemia impairs anastomotic healing. Hyperbaric oxygen increases anastomotic healing of both normal and ischemic colonic anastomosis and reverses ischemic damage. This study demonstrated that hyperbaric oxygen improves anastomotic healing.

Effect of bowel preparation and a fiber-free liquid diet on expression of transforming growth factor and procollagen in colonic tissue preoperatively and postoperatively

PURPOSE

Dehiscence of colonic anastomoses is prevalent and potentially fatal. In an attempt to reduce the likelihood of anastomotic dehiscence, the colon is cleansed before surgery and fiber-free diets are prescribed postoperatively. However, fiber-free diets induce colonic atrophy and impair healing. This study was designed to investigate the effect of bowel preparation and postoperative fiber-free diet on the local gene expression of transforming growth factor-beta 1 and procollagen type I.

METHODS

Four Sprague-Dawley rats underwent bowel preparation with a fiber-free liquid diet and polyethylene glycol in a balanced electrolyte solution for two days (fiber-free preoperative diet group), whereas four rats received standard chow with fiber (preoperative diet with fiber group). On the third day tissue was obtained from the descending colon of each rat to assess the effect of bowel preparation. Forty additional rats had their bowels prepared and underwent transection of the descending colon and anastomosis. These rats were then randomly assigned to continue on the liquid diet (fiber-free postoperative diet group) or rat chow (postoperative diet with fiber group). On postoperative days 3, 5, 6, 7, and 14, colonic tissue was obtained from the anastomosis and analyzed with the use of semiquantitative reverse transcriptase-polymerase chain reaction to examine the relative expression of transforming growth factor-beta 1 and procollagen type I genes normalized to that of a constitutive gene.

RESULTS

There was a decrease in the expression of the transforming growth factor-beta 1 and the procollagen type I genes in the fiber-free preoperative diet group compared with the preoperative diet with fiber group; however, this difference only reached statistical significance for procollagen type I. Postoperatively, significant increases in the expression of the transforming growth factor-beta 1 and procollagen type I genes over baseline levels were observed around postoperative day 7 in both groups, which temporally correlates with active phases of collagen deposition in the wounded colon. Expression of the procollagen type I gene, however, was significantly decreased at this time in the fiber-free postoperative diet group compared with the postoperative diet with fiber group.

CONCLUSION

Although necessary to reduce septic complications, preoperative bowel preparation has a detrimental effect on the expression of transforming growth factor-beta 1 and procollagen type I. A postoperative fiber-free liquid diet also may be detrimental to the expression of these transcripts in the bowel. Alternative methods for delivery of colonic fuels are needed to create a better environment for colonic healing while eliminating bacteria and bulk.

Intraoperative colonic lavage in emergency surgical treatment of left-sided colonic obstruction

PURPOSE

The study contained herein was undertaken to verify if immediate resection with anastomosis with on-site lavage in emergency treatment of left colon obstruction is a safe alternative to the multistage procedure, to look for solutions to practical problems outlined by previous authors, and to check the hospital stay.

METHOD

Between 1991 and 1995, all patients (61) admitted with left colon obstruction were treated with intraoperative colonic lavage and primary anastomosis. Personal development of Dudley's technique is reported. Complications and mortality are pointed out. Later, endoscopy was performed to check the status of all survivors.

RESULT

Low mortality (2 percent) and major complication rates (3 percent) and short hospital stay (11 days, except for patients with major complications) are reported in our series.

CONCLUSION

One-stage surgery with intraoperative lavage is a safe procedure. Patients have a better quality of life (no stoma occurred) with an effective cost-savings.

Role of matrix metalloproteinases in healing of colonic anastomosis

PURPOSE

The aim of this study was to compare the distribution of the matrix metalloproteinases (MMPs) during anastomotic healing in a normal colon with that in an ischemic colon in a rabbit. This family of enzymes degrades all components of connective tissue and has been implicated as a cause of anastomotic dehiscence.

METHODS

A left-sided anastomosis was formed in the distal colon of one group of rabbits, and in the other group, 9 cm of distal colon was made ischemic before resection and anastomosis 12 hours later. Tissues from the anastomosis and sites around the colon were removed at 12 hours, 1 day, and 3 days after anastomosis and, also, at 7 days in the normal group. Distribution of the MMPs and their inhibitor, tissue inhibitor of metalloproteinases (TIMP), was localized by indirect immunofluorescence.

RESULTS

In rabbits having only an anastomosis, the MMPs and TIMP-1 were, at all times, seen solely in the anastomotic segment and were strictly confined to the immediate vicinity of the suture line. While in rabbits with an ischemic colon before anastomosis, the MMPs initially extended several centimeters proximally and distally from the suture line. By the third day, however, there were only minor differences between the two models.

CONCLUSION

Distribution of the MMPs and TIMP-1 in normal healing is consistent with a role in the remodeling of colonic anastomosis, but when healing of the colon is compromised, these enzymes are more widespread and may contribute to anastomotic dehiscence.

Sliding, absorbable, reinforced ring and an axially driven stent placement device for sutureless fibrin glue gastrointestinal anastomosis

Reduced blood flow of from 43 to 71% has been reported in sutured and stapled anastomoses. The sutureless sliding, absorbable, intraluminal, nontoxic stent (SAINT)-fibrin glue anastomotic method, which clamps the stump margins between 2 dissolving surfaces, includes only two stages of temporary compression (about 6 min total using 4 IU/mL thrombin) during the glue application in order to promote vascularization. A SAINT placement device (SAINT-PD) was introduced to facilitate low rectal anastomoses. Morphohistologic results from limited trials using fibrin glue with an untied sutureless stapler technique and a prototype non-gear-driven SAINT-PD, neither having the two dissolvable clamping surfaces of the SAINT, showed a 29 and 25% incidence of intraluminal tissue ridges, respectively. Since these tissue ridges could result in subclinical dilatation or frank stenosis, and the more extensive SAINT trials had an 8% incidence of tissue ridges, redesign of the SAINT-PD was undertaken. Consequently, to improve the anastomotic quality of the SAINT-PD, the sliding absorbable reinforced ring (sucrose base) acting as the second dissolvable surface for the SAINT-PD and a new axially controlled geared SAINT-PD design are described.

Influence of pulsed electromagnetic fields on healing of experimental colonic anastomosis

PURPOSE

The study investigated the influence of pulsed electromagnetic fields (PEMFs) on the mechanical strength and collagen content of uncomplicated colonic anastomosis in rats.

METHODS

A standardized left colonic resection was performed 3 cm above the peritoneal reflection, and end-to-end anastomosis was constructed with eight interrupted inverting sutures. Beginning immediately after surgery, randomly assigned groups were exposed to one of the following: 1) 100 Hz (frequency), 1 mT (intensity) PEMFs with 16-hour on/8-hour off cycles (n = 8); 2) 100 Hz, 2 mT PEMFs with 16-hour on/8-hour off cycles (n = 8); 3) 100 Hz, 1 mT PEMFs with 6-hour on/6-hour off cycles (n = 6), whereas the control group (n = 10) received no PEMFs. Relaparatomy was performed at 72 hours postoperatively, and the bursting pressure of the anastomotic segment was recorded in situ. The hydroxyproline contents of the anastomotic and adjacent perianastomotic segments of equal lengths were determined.

RESULTS

Mean bursting pressure values of the groups that received 100 Hz, 1 or 2 mT PEMFs with 16-hour on/8-hour off cycles (90.88 +/- 19.13 and 83.88 +/- 7.08 mmHg, respectively) were significantly higher than those of the control group (61.66 +/- 10.6 mmHg) and the group with 6-hour on/6-hour off cycles (64.83 +/- 7.36 mmHg; P < 0.05 for all comparisons). Hydroxyproline contents of the anastomotic and perianastomotic segments were consistently higher in the 16-hour on/8-hour off PEMF groups, compared with those of the corresponding segments of the control group.

CONCLUSIONS

PEMFs applied externally to unrestrained rats within a "window of PEMF parameters" provided a significant gain in the mechanical strength of the colonic anastomosis, at least 72 hours post-operatively. Associated relative increases in the hydroxyproline contents of the (peri)anastomotic colonic segments suggest that an altered collagen metabolism might contribute to this enhancement of the anastomotic repair. Further investigations based on these preliminary data and the definition of the exact measures regarding the effects of PEMFs on biologic systems, in general, may lead to an efficient and new adjunctive modality in colorectal surgery.

Extraperitonealization of the anastomosis and sacral drain in restorative surgery for rectal carcinoma: a safety mechanism in the absence of a covering stoma

A retrospective 10-year study was conducted on 473 patients who underwent rectal cancer surgery, to evaluate a surgical procedure which has been generally abandoned, but which we believe has a significant potential to reduce the incidence of the severe and often fatal complications caused by anastomotic breakdown following low anterior resection, especially when a covering stoma is absent. This procedure involves separating the anastomosis and sacral drain from the abdominal cavity by suturing the parietal peritoneum to the colon and mesocolon, and placing the sacral drain outside the peritoneal cavity, whereby contamination of the abdominal cavity is avoided should anastomostic leakage occur. Sphincter preservation was possible in 343 patients (72.5%) while 116 (24.5%) underwent abdominoperineal resection (APR). Of 331 patients who underwent sphincter-saving resection (SSR), 31 (9.4%) had primary protective colostomies. Radical RO-resection according to the International Union Against Cancer (UICC) was performed in 405 patients, and 65 (19.6%) underwent extended resections. Anastomotic leakage became clinically manifest in 33 patients (10%; or 11% when those with primary colostomies were excluded). Only 1 patient required relaparotomy while 32 were successfully treated with temporary loop colostomy in the right epigastrium. No deaths occurred following anastomotic leakage breakdown. Overall operative hospital mortality was 3.0%; 2.7% and 2.6% in the SSR and APR groups, respectively. The adjusted 5-year survival rates were 60% for APR and 72% for SSR.

Esophageal anastomosis: an experimental model to study anastomotic healing and the use of lyophilized collagen

This experimental study assessed the use of lyophilized collagen to reinforce cervical esophageal anastomosis in rabbits. Twenty New Zealand White rabbits weighing 2.3-3.2 kg were used. In group I (n = 10) a 1-cm-long segment of the esophagus was excised and the two free edges anastomosed, to mimic the conditions found in newborn esophageal atresia. Group II (n = 10) had a segmental esophageal resection and end-to-end anastomosis as in group I but the anastomotic site was circumferentially covered with lyophilized type I collagen film. The resected segments were processed immediately and served as controls for the postoperative tissue in each animal. The animals were starved for the first 24 h and water was given on the 2nd postoperative day; on the 3rd postoperative day the animals were allowed a normal diet. Two rabbits in group II died on the 7th and 8th postoperative days because of a fistula. All the rabbits were killed on the 10th postoperative day and 4-cm segments of esophagus with the anastomosis at the centre were removed. At this time gross leakage was detected in four animals (one in group I and three in group II). Each anastomosis was evaluated for bursting pressure, collagen content, and histologic appearance. Bursting pressure was higher in group I. Collagen (measured as hydroxyproline) levels in anastomotic and adjoining 1-cm segments were compared with concentrations in control segments resected during operation. In group II animals there was a significant reduction in the lowering of hydroxyproline concentrations around the anastomosis. Microscopic evaluation revealed no significant differences between the two groups. This experiment showed no demonstrable benefit from the use of lyophilized collagen in preventing the esophageal anastomotic leakage that occurs in repaired esophageal atresia.

Prospective study of hand-sutured anastomosis after colorectal resection

A total of 370 patients underwent colorectal resection: 320 had a primary single-layer seromucosal anastomosis without a protective colostomy, 22 had Hartmann's procedure and 28 abdominoperineal resection. There were 260 elective procedures and 110 patients had peritonitis and/or bowel obstruction at the time of surgery. Overall the mortality rate was 2.7 per cent, the morbidity rate was 18.3 per cent and clinical anastomotic leak rate 3.4 per cent. After elective operation, the leak rate for intraperitoneal anastomosis was 0.6 per cent and for low extraperitoneal anastomosis 7 per cent. The mortality rate was 1.2 per cent and morbidity rate 11.9 per cent. Patients with peritonitis had a significant increase in morbidity rate (46 per cent) in comparison with those having elective surgery (chi 2 = 31.5, 1 d.f., P < 0.0001). Patients who had bowel obstruction and no bowel preparation had a significantly higher morbidity rate of 26 per cent and mortality rate of 7 per cent, compared with those having an elective procedure (chi 2 = 11.2, 1 d.f., P < 0.001; chi 2 = 8.7, 1 d.f., P < 0.005 respectively). Patients having palliative surgery had the highest mortality rate (19 per cent), compared with those operated on with curative intent (1.5 per cent) (chi 2 = 28.7, 1 d.f., P < 0.0001). Cost-saving hand-sutured anastomosis is effective and, in experienced hands, technically feasible after all kinds of colorectal resection and should remain the standard in colorectal surgery.

High morbidity rate after converted laparoscopic colorectal surgery

Sixteen of 65 laparoscopically assisted colorectal operations were converted to an open procedure, usually because of dissection difficulties. Conversion was decided early in the procedure in four cases without perioperative morbidity and later in 12 cases, after a mean of 56 min. The results in patients undergoing converted operation were compared with those in 252 having a planned open colorectal procedure during the same period. The groups were comparable with regard to age, health status, factors influencing intestinal healing and grade of surgeon. A higher postoperative morbidity rate (50 versus 21 per cent) and more anastomotic leakages (25 versus 8 per cent) were apparent in the converted group. Operating time, postoperative ileus and hospital stay were longer in those requiring a converted operation. These poor results suggest that careful preoperative patient selection for laparoscopic procedures and a rapid decision to convert in case of difficulty are important.

Resection and anastomosis of obstructed left colonic cancer: primary or staged?

A retrospective analysis of the treatment of 70 patients with obstructed left colonic cancer was undertaken in order to assess whether staged or primary resection was more appropriate. Thirty-four patients had initial colostomy and staged resection (group 1) while 36 patients were treated by primary resection and immediate anastomosis following intra-operative bowel washout (group 2). There were seven deaths (10%), five in group 1 and two in group 2. The wound infection rate and average hospital stay were 44% and 36 days in group 1 and 19.4% and 16.5 days in group 2, respectively. Twenty per cent of patients in group 1 did not complete their staged procedures and had to live with their colostomies. The smoother postoperative recovery and shorter hospital stay was particularly significant in group 2 patients. As primary resection and anastomosis can now be performed with relative safety and reduced morbidity, we conclude that staged procedures can no longer be accepted as standard treatment for left colonic obstruction.

Is mechanical bowel preparation necessary before primary colonic anastomosis? An experimental study

The necessity of preoperative or intraoperative mechanical bowel preparation of the colon, before primary anastomosis, has been recently challenged in clinical elective and emergency situations.

PURPOSE

This experimental study in dogs investigated the safety of segmental resection and primary anastomosis in the unprepared or loaded colon.

METHODS

Two segments of the descended colon were resected and anastomosed in each animal. Group I (12 anastomoses) received preoperative mechanical bowel preparation; the colon was not prepared in Group II (16 anastomoses); in Group III (12 anastomoses), a preliminary distal colonic obstruction was produced, and during the subsequent resection the colon was loaded. Postoperatively, animals were observed clinically, and anastomoses were assessed at autopsy on the ninth day.

RESULTS

All animals recovered uneventfully. At autopsy there was no evidence of anastomotic leakage.

CONCLUSIONS

In light of recent clinical reports and this experimental study, the ritual of mechanical bowel preparation should be further scrutinized.

[Animal experiment studies of treatment of benign anastomotic stenosis of the colorectal area by electro-incision and balloon dilatation]

In an experimental study the significance of local electroincision and pressure in endoscopic dilatation therapy of benign colorectal anastomotic stenosis was investigated. A benign anastomotic stenosis was induced in the proximal part of the rectum in 21 pigs and was quantified and classified 12 weeks postoperatively using the stenosis index of McAdam. All stenotic anastomoses were dilated using electroincision (two incisions versus four) and balloon dilatation (230 mmHg versus 460 mmHg). Neither perforation nor severe bleeding occurred in any of the animals. At 24 weeks after the operation the anastomoses were restaged. We found significantly better results after four incisions than after two. After multiple incisions the dilation pressure was of secondary importance. Combined therapy with multiple incisions and balloon dilatation is a safe procedure yielding good results even with low-pressure dilatation.

Effect of transforming growth factor beta and basic fibroblast growth factor on steroid-impaired healing intestinal wounds

A longitudinal intestinal wound model in the pig was used to assess the effect of parenteral steroids (betamethasone 12 mg 50 kg-1 intramuscularly twice daily) on breaking load. Steroid treatment significantly decreased the breaking load of wounds in the ileum and colon in comparison with wounds from saline-treated animals. In a further group of animals receiving steroids, paired longitudinal wounds were constructed. One wound of a pair was treated with a local application of transforming growth factor beta (TGF-beta) (5 micrograms per wound) or basic fibroblast growth factor (5 micrograms per wound) in a collagen suspension. The other wound was treated with a collagen suspension alone. Ileal wounds treated with TGF-beta were significantly stronger than collagen-treated controls at 7 days. The steroid-induced impairment of breaking load in intestinal wounds is partially reversed by a local application of TGF-beta in a collagen suspension at the time of surgery.

Prospective audit of an extramucosal technique for intestinal anastomosis

A computerized prospective audit was conducted of 500 intestinal anastomoses constructed in 470 operations on 461 consecutive patients between 1 January 1986 and 16 November 1990. All anastomoses were constructed by an open extramucosal method, emphasizing the avoidance of sutures through mucosa and avoiding the use of intestinal clamps. There were 214 men and 247 women, with a median age of 66 years. Clinical anastomotic leakage was detected from 11 (2.2 per cent) of 500 anastomoses. There were 18 (3.8 per cent) deaths resulting from the 470 operations, but only two (0.4 per cent) were associated with anastomotic leakage, which was not the direct cause of death in either. Peritonitis occurred as a consequence of leakage in two (8 per cent) of 26 resections for Crohn's disease, but the patients survived after reoperation. The single-layer extramucosal technique is probably the safest method available for intestinal suture.

Anastomotic leaks in colorectal cancer surgery: a risk factor for recurrence?

This study examines anastomotic leaks as a potential influence on the long term outcome of patients with colorectal cancer. 167 patients were studied who had clinical and radiological assessment of anastomotic integrity in the post-operative period, following potentially curative resections for left-sided colonic or rectal cancer. There was no evidence of a leak in 135 of these patients, while the remaining 32 developed a clinical and/or a radiological leak. At the end of a mean follow-up of 25 months, 15 patients with leaks (46.9%) developed tumour recurrence, compared with 25 of those without any leak (18.5%; p less than 0.001). Cancer specific mortality at 24 months was also significantly higher for patients with leaks (36.9% +/- 9.7% versus 12.6% +/- 3.3%; p less than 0.001). The influence of anastomotic leaks on the outcome was independent of tumour stage. These results suggest that in patients undergoing surgery for colorectal cancer development of an anastomotic leak is significantly associated with a poorer long-term outcome.

Principles of surgical technique in the treatment of carcinoma of the large bowel

The principles of surgical technique for the operative management of colon cancer are described. With the background of the evolution of anastomotic alternatives, the methods for reestablishing intestinal continuity and the approach to the treatment of complicated presentations of colonic cancer are reviewed. While one may construe this paper to have a certain author bias, I have tried to present diverse options where pertinent, but there should be little question as to where my opinion lies.

Advantages of handsewn over stapled bowel anastomosis

Bowel anastomoses are conventionally performed using a handsewn technique or a stapling device. Each has potential benefits and disadvantages. The most clinically significant complications of the bowel anastomosis are anastomotic leakage and stricture formation. The indices of healing and tissue cohesion were compared dynamically over time in 24 dogs randomized to undergo either a standard two-layer handsewn anastomosis or a stapled anastomosis with the Premium CEEA (United States Surgical Corporation, Norwalk, CT). Animals were sacrificed at 1, 4, 7, and 28 days postoperatively. Each anastomosis was evaluated for anastomotic index, burst pressure, collagen content, and histologic appearance. The anastomotic index was similar on postoperative day (POD) 1, 4, and 7; but on day 28 all handsewn anastomoses had larger diameters than the widest CEEA anastomosis. Burst pressure was higher in handsewn anastomoses at all intervals. Collagen content tended to be higher on POD 7 in the CEEA anastomoses. Histological evaluation showed more complete epithelialization and less inflammation in handsewn anastomoses on POD 28. The higher level of collagen in the CEEA anastomoses on POD 7 may be implicated in the tendency toward stricture formation found with this type of anastomosis. This study demonstrates that the greater speed and ease of the stapled anastomosis is offset by the greater strength, reduced tendency to stricture, and more complete healing of the handsewn anastomosis.

Prospective, randomized trial of the biofragmentable anastomosis ring. The BAR Investigational Group

A randomized trial was undertaken to compare the biofragmental anastomotic ring (BAR) with conventional intraperitoneal colorectal anastomotic techniques. Patients were randomized into one of two schemes: BAR versus sutured or BAR versus stapled anastomosis. There were 782 patients entered into the study and 283 patients (36%) had a sutured anastomosis, 104 patients (13%) had a stapled anastomosis, and 395 (51%) had the BAR. Comparison of the BAR with combined suture and stapled controls revealed no significant differences in wound complication, abscess rate, bleeding, anastomotic leaks, ileus, obstruction, or deaths. There were no differences in return of bowel function, return to normal diet, or hospital stay. Intraoperative difficulties occurred in 46 BAR patients (17%), and this was significantly higher (p less than 0.001) than for sutured (3%) but not for stapled anastomoses (11%). The occurrence of these problems did not adversely effect the outcome. The data suggest that the BAR is a safe, satisfactory alternative to sutured or stapled colorectal anastomoses.

Direct measurement of collagenase in colonic anastomosis

Collagenase has been implicated in colonic anastomotic dehiscence but the enzyme has not previously been specifically measured in colonic healing. A 72 h tissue culture method for colonic tissue and a radiochemical assay for collagenase were adapted to measure the enzyme in healing rabbit colon, with specificity of the assay confirmed by sodium dodecylsulphate polyacrylamide gel electrophoresis. Normal and postoperative colon secreted collagenase, predominantly in a latent form, in the first 24 h of culture. Total activity reached a plateau after 48 and 72 h in culture, when 50-70 per cent of the enzyme was in an active form. At these times in culture, activity was significantly higher than after 24 h (P less than 0.001). One day after anastomosis the total amount of collagenase secreted in culture was higher than normal but the increase did not achieve significance. Three days after anastomosis the colon secreted more collagenase than explants from 1 day postoperative tissue (P less than 0.002). The proportion of active enzyme in the first 24 h in culture was also increased. Since active collagenase can be measured in culture medium from both normal and postoperative colon, the tissue may be secreting plasminogen activator which allows plasmin to activate the enzyme. The increase in collagenase after operation coincided with a decrease in collagen concentration in the colon wall, measured by hydroxyproline. This supports previous suggestions that collagenase contributes to anastomotic dehiscence. However, the findings must be interpreted with caution as the variance of the results was shown to be predominantly due to time in culture, suggesting this could be a bigger influence than the operation itself. In addition, our previously reported immunohistochemical study of this system indicated that collagenase only occurred in a localized region, restricted to the everted portion of the anastomosis, with the activity being tightly controlled by its inhibitor, tissue inhibitor of metalloproteinases.

Healing of experimental intestinal anastomoses. Parameters for repair

Anastomotic dehiscence remains a major complication in surgery of the large bowel, and studies on the healing sequence of experimental anastomoses are necessary to define underlying mechanisms and find ways to improve surgical outcome, particularly in high-risk situations. For the quantitative description of anastomotic repair, both mechanical and biochemical parameters are employed, each with their own limitations. Mechanical parameters, either bursting pressure or breaking strength, only reflect growing anastomotic strength as long as disruption occurs within the anastomotic area, which is less than one week after surgery for the bursting pressure and probably up to two weeks for the breaking strength. The biochemical description of anastomotic repair has been limited to behavior of collagen, as represented by its rather unique constituent amino acid hydroxyproline. Conclusions based on collagen concentrations--per unit weight--should be considered with caution since they may change as a consequence of changes in noncollagenous substances. In this respect, collagen content, per unit length, is probably a better parameter to describe anastomotic collagen levels. Few investigations have addressed the quality of collagen (e.g., crosslinking or type). Since, at this time, no distinct correlations have been demonstrated between development of mechanical strength or occurrence of leakage and collagen levels in the healing anastomosis, attention should not be restricted to a description of the quantity of collagen present: the quality of anastomotic collagen should be investigated, perhaps even more so.

Intraoperative air testing of colorectal anastomoses: a prospective, randomized trial

A total of 145 consecutive patients receiving a colorectal anastomosis were randomized to 'test' or 'no test' once the anastomosis had been completed. Anastomotic testing was performed with the pelvis filled with saline and the rectum distended by sigmoidoscopic insufflation of air. Any leaks demonstrated were oversewn. A water-soluble contrast enema was performed on the tenth postoperative day. Seventy-four patients were randomized to 'test' and 71 to 'no test' but one patient was withdrawn from each group leaving a total of 143 for analysis. The two groups were well matched for age, sex, diagnosis and operative details. Eighteen (25 per cent) air leaks were detected and repaired in the 'test' group. After operation there were three (4 per cent) clinical leaks in the 'test' group and ten (14 per cent) in the 'no test' group (Fisher's exact test, P = 0.043). There were eight (11 per cent) radiological leaks in the 'test' group and 20 (29 per cent) in the 'no test' group (P = 0.006). Intraoperative air testing and repair of colorectal anastomoses significantly reduces the risk of postoperative clinical and radiological leaks.