Abstract: Rectal injury and rectovaginal fistula are rare in clinical practice, but once they occur, they can bring great physical and psychological harm to patients. They are difficult to manage clinically, and if they are not treated properly, they may cause serious complications, which can seriously affect the quality of life of patients in the future. Therefore, rectal injury and rectovaginal fistula should be actively treated. Once they are diagnosed, they should be treated at the right time according to the etiology, lesion location, local condition and patient’s general condition, and the appropriate surgical procedure should be chosen to reduce complications, increase the cure rate and improve the patient’s quality of life. Keywords: rectal injury; rectovaginal fistula; diagnosis; surgical treatment Rectal injury and rectovaginal fistula are rare in clinical practice, but once they occur, they can bring great physical and psychological harm to patients. And clinical management is difficult, if not properly handled, the condition is likely to be prolonged and even cause serious complications, which can seriously affect the quality of life of patients in the future. Rectal injury Because the rectum is located in the terminal part of the gastrointestinal tract, close to the pelvic sacral recess and protected by the solid pelvis, the incidence of rectal injury in abdominal trauma is low in both peacetime and wartime. For example, rectal injuries in our army in the self-defense counterattack against Vietnam only accounted for 5.5%-12.9% of abdominal trauma [1]. The incidence of rectal injuries in total colorectal injuries is also low in most literature reports. Rectal injuries above the retroperitoneum account for approximately 9.17% of colorectal injuries, and rectal injuries below the retroperitoneum account for approximately 8% of colorectal injuries. Because the rectal contents are formed feces, the highest bacterial content, more tissue gaps around the rectum, and rectal injury is often combined with urethral and sacrococcygeal injuries, so once the injury, it is very easy to infect, and easy to spread to the surrounding tissues, causing difficulties in the treatment. (a), the etiology of rectal injury 1, rectal trauma (1) penetrating trauma (such as gunshot wounds, sharps piercing injuries, rod-shaped inserted injuries when falling from a height), is the most common cause of rectal injury, accounting for more than 95% [2]. (2) non-penetrating trauma (such as blunt force trauma) (3) riding across the injury 2, medical injury (1) endoscopy or electrosurgery injury (2) barium enema examination (3) pelvic surgery injury (4) other surgical injuries 3, rectal foreign body: such as denture, dental bridge or fish bone fragments and other sharp foreign body swallowed into the rectum injury. (a), rectal injury diagnosis points 4, mostly lower abdominal, perineal trauma history or history of rectal endoscopy. 5, rectal injury above the peritoneal fold can appear sudden abdominal pain, abdominal pressure, rebound pain, abdominal muscle tension and other manifestations of colonic injury. 6, rectal injury below the peritoneal fold can often appear: (1) lower abdominal pain, defecation, urination difficulties; (2) bleeding fluid from the anus, is an important sign for the diagnosis of rectal injury; (3) perineal, buttock, femoral open wounds with fecal leakage; (4) sacrococcygeal pressure pain, perineal swelling, etc.; (5) rectal finger examination, visible finger sleeve with fresh blood, low-level injury can be found in the injury (5) rectal finger examination, fresh blood in the finger sleeve, low-level injury can be found in the injury location, wound size and number. 7, often combined with bladder, urethra and vaginal injuries, can be seen in the urine with fecal residue, urine from the anus and other abnormal phenomena. 8.Laboratory examination: blood leukocytosis can be found, and in severe cases, red blood cell reduction, hemoglobin and leukocyte specific volume decrease. 9.Anorectal microscopy: the site and extent of low rectal injury and its severity can be clearly seen. 10, X-ray examination: rectal injury above the peritoneal reflex sometimes exists in the abdominal cavity free gas. Pelvic radiographs can understand the presence or absence of fractures and foreign bodies. Absolutely prohibit the injection of air, barium and other substances into the anal canal, so as not to accelerate the spread of infection. (B), treatment methods of rectal injury The measures of rectal injury treatment mainly include fecal diversion, injury site repair, distal rectosigmoid irrigation and adequate presacral drainage [1]. Once diagnosed, rectal injury should be treated with early surgery, and different treatment options should be selected according to the cause, location, and severity of the injury. 1, rectal injury above the peritoneal refracture: perform a dissection to find the breakage, such as minor injury, then repair; if the injury is serious, then perform resection and end-to-end anastomosis; according to the patient’s general condition, the degree of intestinal cleanliness and the degree of abdominal contamination to decide whether to perform a diversionary proximal colostomy (generally sigmoid stoma is better), to ensure the smooth healing of the anastomosis, to be 3-6 months after surgery, the second stage of stoma also The second stage of the stoma will be performed after 3-6 months. 2, rectal injury below the peritoneal reflex: if the injury is limited to the mucosa can be rinsed after dressing with petroleum jelly gauze, if the injury involves the muscle layer can be cleared and sutured; such as rectal full-layer injury and the involvement of perirectal tissue, should be in the rectum after the perineum incision and excision of part of the tailbone, removal of foreign bodies, broken bone fragments, hemostasis after repair of the damage. However, it should not be reluctantly repaired. Postoperatively, a drainage tube should be placed around the rectum for adequate drainage. If there is a rupture of the anal sphincter, it should be sutured. To ensure adequate postoperative drainage, the perineal incision can be left unstitched and changed after surgery. If the rectal injury is large and the contamination is serious, a proximal colostomy should be performed. 3, the medical source of rectal injury mostly occurs above the peritoneal reflex, such as timely detection can be immediately surgical repair, such as intestinal preparation, pollution is not heavy can not be proximal colostomy. 4, perioperative application of broad-spectrum antibiotics. 5, the late treatment of rectal injury is mainly aimed at anal canal rectal stenosis, anal incontinence and partial loss of the rectal wall. II. Rectovaginal fistula Rectovaginal fistula is a pathological channel formed between the anterior wall of the rectum and the posterior wall of the vagina (see Figure 1). It is a special disease that is clinically rare but very harmful, and its formation is complex, and if not treated properly, it can easily recur or leave sequelae, which can bring a heavy burden to female patients not only physiologically but also, and more importantly, psychologically, and seriously affect their quality of life [3]. (A) Clinical manifestations and etiology of rectovaginal fistula Patients with rectovaginal fistula mainly present with vaginal fecal overflow, which is especially noticeable during diarrhea or relieving loose stools, and sometimes with vaginal discharge. The diagnosis can be made on the basis of typical clinical manifestations and rectovaginal examination, which can be further confirmed in some patients by probing, fistulography, endoscopy or melanoma stain test. Rectovaginal fistulas can be classified into two categories, congenital and acquired, depending on the etiology. Congenital rectovaginal fistulas are generally a comorbidity of congenital anorectal malformations. The etiology of acquired rectovaginal fistulas is more complex and includes: 1. trauma (e.g., rectovaginal penetrating injury); 2. infection (e.g., perirectal abscess); 3. tumor (e.g., rectal or cervical cancer); 4. inflammatory bowel disease (e.g., Crohn’s disease); and 5. injury of medical origin: birth injuries are the most common [4]. In addition, in the clinical practice of gynecology, colorectal surgery and even oncological radiotherapy, any medical injury that damages the structure of the rectovaginal compartment and leads to the communication between the rectum and the vagina can form a rectovaginal fistula. （The aim of rectovaginal fistula treatment is to close the fistula to avoid recurrence, protect the anal sphincter function and shorten the healing time. Since fistulas are not healed, they are often combined with varying degrees of local inflammation due to the long-term stimulation of fecal matter that harbors a large number of bacteria, and fibrous scar tissue often forms around the fistula, so conservative treatment is often ineffective. Surgical repair is the only cure for rectovaginal fistula, but the timing of surgery should be carefully chosen. The timing of surgery for congenital anal atresia combined with rectovaginal fistula is very small, and in cases where defecation is difficult after birth, a diversionary enterostomy can be performed in the neonatal period. If the fistula and the vaginal opening seem to be close to each other, then anoplasty is performed after 4 to 5 years of age. If the vaginal fistula is large and the feces is discharged freely, early surgery is not necessary, and surgery is more appropriate at the age of 3-5 years. The timing of surgery for acquired rectovaginal fistula For acquired rectovaginal fistula, especially those of medical origin, do not operate immediately because the patient urgently wants it. Surgery should wait until all inflammation has subsided and the scar has softened, 3 months after the injury or repair has been performed. If the fistula is large wait for 6 months. Also all inflammation must be properly drained. There is still controversy as to whether to perform a temporary diverting enterostomy prior to repair surgery. However, most scholars believe that although a diverting enterostomy places an additional burden on the patient, it does increase the chances of healing. （The choice of surgical approach to rectovaginal fistula is crucial for a successful repair of rectovaginal fistula. There are many surgical options for repairing rectovaginal fistulas, but it is still a question of how to choose the best procedure for a specific case to achieve the best result with the least damage. In addition to the patient’s general condition, the etiology, location and size of the fistula, and the operator’s experience should be taken into account in selecting the procedure. Congenital rectovaginal fistulas often require plastic surgery such as anoplasty for repair. Most cases of obstetric injury (mishandled birth) are low rectovaginal fistulas and are often repaired by obstetricians and gynecologists using the transvaginal route in which they specialize. For other medical injuries, the surgeon or obstetrician-gynecologist will focus on the location of the fistula and combine his or her experience with a variety of surgical options, including transabdominal, transanal, perineal, transvaginal, and transanal sphincter repair (i.e., Mason’s procedure [5]). Transabdominal repair is indicated for high and intermediate (especially high) rectovaginal fistulas. For simple fistulas repair can be achieved using direct visual fistula excision with layered sutures. However, complex fistulas or rectovaginal fistulas following radiation therapy require either a Parks coloanal sleeve anastomosis or a transabdominal anal drag-out proctocolectomy (Maunsell-Weir procedure). These two procedures completely isolate the vaginal wall from the rectum, completely eliminating the most important factor in fistula formation, and have a high success rate for first-stage surgery, but are complex and have a high rate of surgical complications. Transanal and perineal repairs are indicated for low-grade rectovaginal fistulas. Transanal fistulas can be repaired by resection of the fistula with layered sutures, however, the more widely accepted method is the transanal rectal advancement flap repair (Endorectal Advancement Flap [6]), which was first applied by Noble in 1902 to treat rectovaginal fistulas and was reported to be 100% curative by Laird in 1948. Recently, most scholars [4, 6] believe that this method should be preferred for low rectovaginal fistulas. Transperineal repair is now rarely used. Almost all obstetricians and gynecologists and some surgeons prefer transvaginal repair of medium and low (especially low) rectovaginal fistulas. Transvaginal repair can also be performed by fistula excision with a layered inversion suture or by vaginal push flap repair [4], and in 2003 Rahman et al [7] reported a 100% cure rate for 39 small low rectovaginal fistulas due to birth injuries over a 15-year period using the former method. However, overall transvaginal repair often does not achieve such satisfactory results. The Mason procedure was originally designed for repairing rectourethral fistulas and was later used mainly for local excision of middle and lower rectal tumors, and in 1998, Qiu Huizhong [5] was the first to report that the Mason procedure was used to treat four cases of refractory rectovaginal fistulas, all of which were repaired successfully in one visit, demonstrating the superiority of the Mason procedure in the surgical repair of middle and low rectovaginal fistulas. The most serious complications after Mason’s procedure are anal incontinence and rectal skin fistula. In fact, these complications can be avoided with strict preoperative bowel preparation and postoperative dietary control, proper incision and anatomical repair of the external anal sphincter. In conclusion, surgical repair of rectovaginal fistulas remains a challenge for the surgeon. Surgeons should be familiar with the various surgical approaches and should choose the best procedure for the patient at the right time to provide the best chance of successful repair.