Haiying DAI ,Minliang WU ,Yuchong WANG,Shuo FANG,Zheng WANG,Yu XIA,Jianguo XU ,Chunyu XUE

ABSTRACT Objective To investigate the application of transposition flaps in the reconstruction of perianal skin defects after tumor resection.Methods From September 2018 to December 2019,16 cases of perianal skin defects were repaired with unilateral or bilateral transposition flaps.The wound size before closure ranged from 4 cm × 8 cm to 7 cm × 10 cm.Fourteen patients achieved primary healing.Wound dehiscence occurred in one patient at the flap tip,whereas a slight infection occurred in another patient,which healed after a dressing change.During the follow-up period of 3-6 months,all patients were satisfied with the perianal area both aesthetically and functionally.Conclusion Transposition flaps are a promising option for the repair of perianal skin defects after tumor removal.Owing to the simplicity of the flap design,the wide popularity of this flap type among surgeons is anticipated.

KEY WORDS Transposition flaps;Perianal wound repair;Negative-pressure wound therapy

INTRODUCTION

Surgical resection remains the mainstay treatment for perianal tumors,especially malignant tumors derived from the skin[1-3].Skin defects after surgical resection often involve the anus,which is difficult to repair.Skin flaps are often used in the reconstruction of this region.Gluteus maximus and gracilis myocutaneous flaps have traditionally been favored,but the surgery is complicated and may cause great donor-site morbidity[4-7].Moreover,late-stage skin contracture after skin grafting may lead to anal contracture,which affects defecation and patient quality of life.Between September 2018 and December 2019,we used transposition flaps[8]to repair 16 cases of wounds after perianal malignant tumor resection.

METHODS

Data Collection

A total of 16 patients (10 men and 6 women) aged 69-81 years were included in this retrospective study.The surgical indications for all patients were tumors in the perianal region,including perianal mucinous adenocarcinoma (4 cases),perianal Paget’s disease (PPD,9 cases),and squamous cell carcinoma (SCC,3 cases).The skin defects after tumor resection were 4 cm × 8 cm to 7 cm × 10 cm.

Surgical Procedures

Preoperative preparation

Preoperative bowel preparation was performed.All patients received a low-residue liquid diet for 3 days.A laxative (magnesium sulfate or polyethylene glycolelectrolyte powder) was given orally twice the day before the surgery,and a cleansing enema was administered until the patient defecated only a clear watery stool.

Tumor resection

All surgical procedures were performed under general or epidural anesthesia.The lesion area was marked (Fig.1A),and the excision was performed according to standard guidelines for each tumor type.The incision was made down to the surface of the deep fascia.The anal sphincter was cautiously maintained during the dissection to avoid anal function impairment.Intraoperative frozen section analysis was performed to confirm clear margins and base.

Fig.1 Reconstruction of skin defect after perianal SCC resection with transposition flaps

Flap design

The transposition flaps were designed near the wounds,and the incision lines were marked (Fig.1B and Fig.2B).The flap width was equal to the maximum width of the wound to be repaired.Bilateral translocation flaps could be designed on both sides for huge wounds.The flap was incised along its entire perimeter down to the deep fascia layer.The dead space was closed tension-free after the advancement of the flap to the appropriate sites.Straticulate interrupted sutures were applied (Fig.1C and Fig.2C),and drainage was placed under the flap and the donor site.For patients with anus involvement,an anal canal was placed,and the wound was locally compressed with negative-pressure wound therapy (NPWT).A fluid only diet was given postoperatively to avoid defecation within 1 week.The stitches were removed at 2 weeks after the operation.

RESULTS

All flaps survived with a good blood supply,and 14 patients’ wounds healed by first intention.For the other two wounds,the flap tip was slightly dehisced in one case,while the wound was infected in the other case.After a dressing change,both wounds healed by second intention.During the follow-up period of 3-6 months,each patient was satisfied with the perianal area aesthetically and functionally (Fig.1D and Fig.2D).

DISCUSSION

Tumors in the perianal region are often difficult to detect at an early stage because of their special location,and patients may feel too embarrassed to seek medical help.These factors may lead to delayed treatment,especially in cases of rapidly growing malignant tumors.As a result,wounds after tumor resection are relatively large,which makes reconstruction difficult.Doctors in some small hospitals in rural areas are incapable of managing such complicated cases,and patients admitted to these hospitals miss the best treatment timing.Since September 2018,we have achieved excellent therapeutic effects in the repair of perianal wounds using local flaps and NPWT with a high satisfaction rate.

Fig.2 Reconstruction of skin defect after perianal SCC resection with transposition flaps

Here,we describe our experience in the reconstruction of perianal skin defects after tumor resection using transposition flaps.Strict bowel preparation is required.Patients have been prescribed a fluid-only diet for 3 days before the operation.In addition,laxatives (magnesium sulfate or polyethylene glycol-electrolyte powder) are ordered to be taken twice orally,and a clean enema is given one day before the operation.Elderly patients with slow intestinal peristalsis will be instructed to increase their activity level to expedite the intestinal peristalsis until a clear watery stool is discharged.The patient with wound infection in this study was an elderly man.Due to insufficient preoperative bowel preparation,stool contaminated the area several times during surgery,leading to the postoperative wound infection.The wound healed after a dressing change by second intention.Intraoperative frozen sections should be performed routinely to confirm clear margins and base and reduce the recurrence rate,especially for patients with a high suspicion or clear diagnosis of malignant tumors.For Paget’s disease with anal mucosa involvement,intraoperative frozen sections must be examined to clarify the surgical margin;if necessary,part of the external sphincter can be removed to keep the internal sphincter intact.

The transposition flap is easy to design with an excellent blood supply,and its length-width ratio can be designed at 1.5:1.If the defected area is located near the gluteal sulcus,the donor site can be designed within it to ensure better concealment after closure.A preoperative Doppler blood flow detector can be used to find and mark subcutaneous perforating vessels in the designed donor site for preservation to increase the flap survival rate.For a huge wound that is difficult to repair using a unilateral flap,a transposition flap can be designed on the other side of the wound.NPWT is recommended for routine application after surgery,as it has been proven in animal experiments and clinical practice that it has the characteristics of vacuum negative-pressure suction (-125 to -50 mmHg),multi-tube drainage,and continuous irrigation;moreover,it can prevent and control infection,promote granulation growth,and accelerate wound healing[9-10].We believe that using NPWT to cover the perianal wound is beneficial,as it can fix the flap to prevent dislocation and keep the wound clean.With fasting,it can be placed for 7 days before removal and the anal canal pulled out at the same time to expose the wound.

Attention should also be paid to postoperative care.The patient must start with a liquid diet after surgery and continue it for 7 days to minimize stool formation.To prevent intestinal secretions and stool from being discharged from the anus and causing wound contamination,the anal canal is used and fixed to the perianal skin with sutures.The application of NPWT can prevent the anal canal from shifting and causing pain[11-12].The anal canal is then removed when a semifluid diet resumes at 7 days after the operation and the wound can be exposed.Daily dressing changes in the wound include iodophor disinfection and washing with chlorhexidine 1-2 times.The diet gradually changes from fluid to semifluid,and a normal diet resumes at about 2 weeks after the operation.

This single-stage operation can achieve primary and secondary wound closure simultaneously as well as a high flap survival rate due to the reliable blood supply in the donor region.During the follow-up period,the texture,tissue elasticity,thickness,and color of the postoperative skin flap were similar to those of the surrounding tissues[13-15].However,this flap has some limitations.It is a local skin flap limited by the length-width ratio,which may limit the maximum repair area.Additionally,since this flap can be harvested down to the subcutaneous tissue,its use is not suitable for repairing wounds with deep tissue defects alone.

Our experience can be summarized as follows.First,this method makes full use of the surrounding tissues to create a local flap.Its flexible design and simple use make it possible to design unilateral or bilateral transposition flaps according to wound size.Second,it can minimize donor-site morbidity because muscle tissue is not included in the flap design.Moreover,the donor and recipient areas are adjacent to each other,which can avoid differences in skin coloration.Third,for wounds with anal involvement,the rate of anal contracture is relatively high after skin grafting.However,the rate of contracture after flap transplantation is low,as it can preserve anal function to the greatest extent and improve patient quality of life.Intraoperatively,care should be taken to maintain the integrity of the perianal sphincter to avoid affecting the defecation function of the anus.Fourth,during the postoperative recovery process,special attention should be paid to diet control.Although all patients are prescribed a fluid diet postoperatively,the consumption of milk or fish soup in some patients will stimulate the gastrointestinal tract,causing diarrhea and being more likely to cause wound infection.Once this happens,the anal canal and wound dressing should be removed immediately,and the wound should be disinfected and exposed.If necessary,oral antidiarrheal drugs can be administered.After each episode of diarrhea,the wound should be disinfected.Fifth,when suturing the skin flap to the receiving area during the operation,the rectal mucosa,perianal sphincter,and distal end of the skin flap must be sutured and fixed.Tension-free sutures must be applied to avoid perianal mucosa avulsion and an effect on anal function.Sixth,although a fluid diet is given postoperatively,the secretion of intestinal fluid may also lead to wound infection.Thus,the use of the anal canal is necessary.In the past,anal canal slippage was prone to occur after insecure fixation;however,it can now be combined with NPWT to not only keep the wound clean and dry but to fix the anal canal to avoid slippage due to changing body positions.

CONCLUSION

The use of transposition flaps to repair perianal skin defects is simple and boasts of a high survival rate.Flap color and texture are similar to those of the surrounding tissues after reconstruction.When combined with NPWT,the anal function is not affected,and the complication rate is low.

ETHICS DECLARATIONS

Ethics Approval and Consent to Participate

This study received ethical approval from the Ethics Committee of Changhai Hospital.All participants provided written informed consent before study enrollment.

Consent for Publication

All the authors have consented to the publication of this article.

Competing Interests

The authors declare that they have no competing interests.The authors state that the views expressed in the article are their own and not the official position of the institution or funder.