Fistulas after radiation therapy (post-radiation fistulas)

A particularly severe complication of radiation therapy for malignant pelvic tumors is post-radiation fistulas, which account for about 8% of all urogenital fistulas. Fistulas after radiation therapy form in 1-5% of patients who have undergone radiation therapy.

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Causes fistulas after radiation therapy (post-radiation fistulas)

The incidence of fistula formation increases with repeated courses of radiation therapy. In the etiology of post-radiation urological complications, both damage to the vaginal and epigastric plexus and the presence of vascular diseases play a role. For example, patients with diabetes mellitus and hypertension develop more severe post-radiation complications. Despite the creation of modern equipment for radiation therapy, the number of patients with various post-radiation complications, including post-radiation urogenital fistulas, remains significant. Surgical intervention also contributes to the disruption of the trophism of the urogenital organs.

Thus, with combined treatment of cervical cancer, the risk of urogenital fistulas increases fourfold. Such complications usually occur late after completion of the course of radiation therapy (on average, after two years), since trophic changes leading to fistula formation progress slowly.

However, there are reports in the literature on fistula formation 28 years after the end of radiation therapy and even 38 years after the end of irradiation. Such a long period from the moment of irradiation to fistula formation allows us to differentiate radiation urogenital fistulas from primary tumor fistulas that occur immediately after tumor destruction. This indicates the participation of trophic disorders in the formation of post-radiation urogenital fistulas.

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Treatment fistulas after radiation therapy (post-radiation fistulas)

Surgical correction is performed after the general condition of the patients has stabilized and the tissues in the fistula area have acquired plastic properties. In this case, inflammation disappears, necrotic areas are rejected and scars soften. Post-radiation fistulas are operated on average 7 months after the end of radiation therapy or the occurrence of a relapse.

It is difficult to close post-radiation fistulas using standard methods; the surgeon must creatively approach the development of the operation. Often, patients are operated on multiple times. Of course, it is increasingly difficult to close a recurrent fistula each time, since after previous operations, the scars in the surrounding tissues become extensive and denser, which worsens the blood supply to the tissues. Repeated operations lead not so much to the restoration of voluntary urination, but to a consistent decrease in the capacity of the bladder, which is already reduced in half of the patients.

In order to improve tissue trophism and replace extensive defects in post-radiation fistulas, most methods are based on the use of a pedicle flap cut from non-irradiated tissues. SR Kovac et al. (2007) believe that fistuloplasty using tissue pads is the main method of surgical treatment of post-radiation urogenital fistulas. Currently, many authors recommend using the Martius flap to close post-radiation urogenital fistulas.

In addition, during surgical treatment of post-radiation fistulas, m. gracilis, m. rectus abdominis, peritoneum and omentum are used as gaskets.

A modification of the Latsko operation has been proposed for the treatment of post-radiation vesicovaginal fistulas. The essence of the proposed method is that after the widest possible mobilization of the vaginal and urinary bladder tissues in the fistula area, the edges of the latter are not excised. Inverted sutures made of synthetic absorbable materials are applied to the bladder wall defect.

If technically possible, a second row of sutures is applied to the paravesical tissues. Sutures are applied to the vaginal defect in such a way that the anterior and posterior vaginal walls are sutured together below the fistula area. That is why the operation was called "high colpocleisis". This method was used to operate on 174 patients with post-radiation vesicovaginal fistulas. Positive results were achieved in 141 (81%) women.

In some cases, with a significant decrease in the capacity of the bladder and involvement of the pelvic sections of the ureters in the process, voluntary urination is restored naturally using intestinal transplants. However, if the capacity of the bladder is irretrievably lost or there are extensive defects in the bottom of the bladder and there is no urethra, the question arises of transplanting the ureters into the intestine along the length or supravesical urine diversion with the formation of Bricker reservoirs. Mainz-Pouch and their various modifications, which ensures normal functional preservation of the kidneys.

Despite compliance with all the rules and principles of surgical interventions, improvement of surgical techniques and creation of suture materials with improved properties, the effectiveness of operations for post-radiation urogenital fistulas remains low. The frequency of relapses in various clinics ranges from 15 to 70%. Thus, in one of the experiments on surgical treatment of 182 patients with post-radiation puerto-vaginal fistulas, voluntary urination was restored in 146 patients (80%). The high frequency of relapses encourages the development and improvement of surgical methods for treating patients with post-radiation urogenital fistulas.