Surgical Evaluation of Autologous Platelet-rich Fibrin Membrane as a Coverage Layer in Repair of Urethrocutaneous Fistula after Hypospadias Surgeries: A Randomized Controlled Trial

ABSTRACT

Purpose:

It has recently been reported that the use of platelet-rich fibrin (PRF) as an extralayer over the urethroplasty has been related to a considerable reduction in fistula rates. Due to the lack of evidence supporting the usage of PRF in urethrocutaneous fistula (UCF) repair, we conducted this study to evaluate the efficacy of PRF in patients with UCF.

Materials and Methods:

We conducted a randomized controlled study on patients with distal fistula after hypospadias repair. Patients were randomized into two groups, one with local dartos coverage and the other with PRF coverage layer.

Results:

In the present study, we included 37 patients; 20 patients underwent local dartos coverage, and 17 patients underwent PRF. The mean age was 22.45 ± 4545 ± 4515 ± ±15.35 (range 11–56) months for the study group and 20.6 ± 66 ± 614 ± ±14.5 (range 6–45) months for the control group. The incidence of recurrent UCF was 11.8% in the treatment group (two patients), whereas the incidence was 30% (six patients) in the control group (P = 0.246).

Conclusion:

UCF surgery may benefit from the use of PRF as a supportive tissue that promotes wound healing, angiogenesis, and tissue restoration. We believe that the use of PRF as a new approach for UCF repair should be investigated further through clinical studies.

INTRODUCTION

One in every 200–300 male newborns is affected with hypospadias, the most prevalent congenital penile deformity.[1] As the most prevalent consequence following hypospadias repair, the incidence of urethrocutaneous fistula (UCF) ranges from 4% to 20%.[2] Complications, including fistulas, are more common when hypospadias is severe.[3] An impairment of the local healing process may be associated with this complication.

Recurrence of UCF also shows a high incidence rate, and many causes can explain this complication as surgical site infection, urethral obstruction or stenosis, poor vascularity, rough surgical techniques, complexity, and lack of surgical experience.[4] There are roles in the repair of UCF to prevent a recurrence, excluding distal stenosis before surgery, doing urethroplasty with healthy, well-vascularized tissue, applying a good covering layer, avoiding ischemia, and rough surgical techniques.[5] Although hypospadias surgery has improved, recurrent UCF continues to be a challenge. Bladder mucosa, fascia lata, tunica vaginalis, and local penile subcutaneous tissue have been used to prevent the recurrence of UCFs.[6,7,8,9]

It has recently been reported that the use of fibrin glue as an extralayer over the urethroplasty has been related to a considerable reduction in fistula rates.[10,11,12] Dohan et al. developed the use of platelet-rich fibrin (PRF).[13] PRF is a fibrin matrix polymerized in a tetramolecular structure containing many leukocytes, cytokines, and platelets.[14,15] Blood components that are beneficial to healing and immunity are concentrated on one fibrin membrane in the form of an immune and platelet concentrate. Tissue healing may be accelerated using it in surgeries involving the mouth, maxillofacial region, and plastic surgery.[16,17] Recently, there has been information on PRF usage in UCF repair.[18] Due to the lack of evidence supporting PRF usage in UCF repair, we conducted this study to evaluate the efficacy of PRF in patients with UCF.

MATERIALS AND METHODS

The present manuscript was prepared in concordance with the recommendations of the CONSORT Statement.[19] The study’s protocol was approved and registered by the Research Ethics Committee of Cairo University Teaching Hospitals (code: MS 429-2021). Parents of eligible patients signed written informed consent before study enrollment.

Study design and patients

We conducted a randomized controlled study that enrolled patients with UCF secondarily hypospadias repair from the period between February 2021 and February 2022. Patients were included if they had a documented UCF after undergoing urethroplasty for hypospadias repair. We excluded patients with a history of repeated hypospadias repair, patients with urethral stenosis or obstruction, and patients with no follow-up data. Eligible patients were randomized in a 1:1 ratio using computer-based randomization software to undergo either local dartos or PRF as a first coverage layer over repair.

Data collection and study procedures

Perioperatively, all patients were assessed for demographic characteristics, urethroplasty technique and type of suture, layers of urethroplasty, fistula characteristics, presence of residual chordee, history of circumcision, presence of meatal opening stenosis, catheter characteristics, and postoperative complications, and presence of fistula, infection, and chordee 3 months postoperatively.

All patients underwent UCF repair under general anesthesia, the fistula was exposed by the circumferential skin incision around it, then the unhealthy devascularized edges of the fistula were discarded, and subsequent repair of the fistula using Vicryl 6-0 sutures over 6 French urinary catheters was done.

In the control group, the local dartos flap was acquired from the ventral penile surface by widening the skin incision around the fistula and dissecting the flap from the dartos layer surrounding the fistula, the pedicled flap is then used to cover the repair and fixed using Vicryl 6-0 suture.

The study PRF group used the same technique using the PRF membrane as a first layer. The PRF was prepared by withdrawing 5 ml of venous blood and transferring it to a sterilized plastic tube with no additives. The tube was placed in the centrifuge at a speed of 3500 rpm for 20 min. Then, the membrane separation from the other two layers was done, and the PRF membrane was placed in normal saline [Figure 1].

Figure 1.

The tube after centrifuging the blood sample containing the layers of platelet-rich fibrin preparation

For PRF final preparation, it was separated from other attached layers and placer over a piece of gauzed then squeezed gently to obtain the flat layer that could be fixed over the repair [Figure 2].

Figure 2.

The platelet-rich fibrin layer after separation from other layers

The final step was to fix the layer over the repair which was achieved by overlying the PRF extract directly over the repair and fixation in the four corners by Vicryl 6-0 sutures was applied [Figure 3].

Figure 3.

The platelet-rich fibrin covering the fistula repair

In both groups, the skin then closed directly over the coverage layer and the urinary catheter was kept in place.

Patients were examined at the time of catheter removal, then assessed at the outpatient clinic on a weekly interval for 1 month then evaluation done after 3 months from the date of the operation.

Statistical analysis

All statistical analyses were performed using IBM Corp. (2020). IBM SPSS Statistics for Windows (Version 22.0) [Computer software]. IBM Corp. Continuous data were expressed as mean (± standard deviation), and categorical data were described as percentages. The association between the type of membrane coverage and perioperative characteristics was tested using the Chi-square test, with P < 0.05 denoting statistical significance.

RESULTS

In the present study, we included 37 patients; 20 patients underwent local dartos and 17 patients underwent PRF. The mean age was 22.45 ± 4545 ± 4515 ± ±15.35 (range 11–56) months for the study group and 20.6 ± 66 ± 614 ± ±14.5 (range 6–45) months for the control group, [Table 1].

Table 1.

Fistula characteristics in each group and used coverage layer after fistula repair

	n (%)	Local dartos (n)	PRF (n)
Type of original operation
GAP	1 (2.7)		1
Unknown	6 (16.2)	3	3
TIP	30 (81.1)	17	13
Fistula location
Coronal	12 (32.4)	7	5
Subcoronal	19 (51.4)	10	9
Midshaft	5 (13.5)	3	2
Penoscrotal	1 (2.7)		1
Number of fistulas
Single	33 (89.2)	18	15
Multiple	4 (10.8)	2	2
Presence of residual chordae
No	35 (94.6)	19	16
Yes	2 (5.4)	1	1
Fistula size (mm)
<3	29 (78.4)	16	13
>3	8 (21.6)	4	4
Meatal stenosis	10 (27)	7	3

GAP: Glandular approximation plasty, TIP: Tubularized incised plate, PRF: Platelet-rich fibrin

Two cases with multiple fistulas were distributed to the control group and the other two cases to the study group, regarding the cases with large fistula, 6 out of 8 patients were distributed to the study PRF group and only two patients were distributed to the control group.

Most of the cases (28 out of 37) were operated by the same surgeon, and all cases were operated by the surgeons having the same level of experience in hypospadias repair and all of them are pediatric surgery consultants.

Recurrent cases postlocal dartos flap was 6 out of 20 (30%), three cases had recurrent coronal and other three cases acquired subcoronal fistula, 5 out of 6 cases had tiny single fistula <3 mm in maximum diameter and only one case had larger fistula more than 3 mm, and one case had recurrent two fistulas. On the other hand, recurrent cases post-PRF were two patients of 17 patients (11.7%), one of the two cases had coronal fistula, whereas the other cases had two subcoronal and coronal fistulas, all fistulas were <3 mm in maximum diameter [Table 2].

Table 2.

Comparison of the results of coverage layers

	Coverage layer			P
	Local dartos, n (%)	PRF, n (%)	Total (n)
Time of the catheter removal in days				0.026
5 days	8 (38.1)	13 (61.9)	21
7 days	12 (75.0)	4 (25.0)	16
Skin dehiscence	4 (50.0)	4 (50.0)	8	1.000
Recurrent fistula	6 (75.0)	2 (25.0)	8	0.246
Persistence of fistula after 1 month	6 (75.0)	2 (25.0)	8	0.246
Persistence of wound dehiscence after 1 month	4 (66.7)	2 (33.3)	6	0.667
Chordee-1 month	0	0	0
Persistence of fistula after 3 months	6 (75.0)	2 (25.0)	8	0.246
Persistence of wound dehiscence after 3 months	0	0	0
Chordee 3 month	0	0	0

PRF: Platelet-rich fibrin

Our findings showed that there were no statistically significant differences between both groups in terms of recurrent fistula (P = 0.24), and the occurrence of fistula within 1 month and 3 months (P = 0.24), whereas there was no marked and statistical improvement in the results after applying PRF membrane, there was a decrease in the incidence of the recurrent fistula rate after applying PRF which may require to work upon more cases to detect significant difference between the two techniques. Interestingly, patients who were treated with continuous suture urethroplasty were associated with a significantly (P = 0.012) lower incidence of fistula, than those treated with simple interrupted sutures (12.5% vs. 43.8%), respectively.

DISCUSSION

Despite advances in suture material and various surgical procedures, the most frequent complication after hypospadias correction is the development of a fistula. Several different grafts and flaps may be utilized to treat or prevent fistulas.[7,8] The lack of healthy, well-vascularized surrounding tissue around the fistula site dramatically limits the use of local tissue flaps, resulting in the need for extragenital tissue grafting.[10] There was also a rise in the use of autologous and homologous fibrin sealants as an alternative to tissue flaps. Many surgical techniques employ fibrin sealants as topical hemostasis and tissue adhesion agents.[20] The use of fibrin sealant in hypospadias surgery was first documented by Kinahan and Johnson.[21] UCF following hypospadias repair may be decreased by administering fibrin sealant to the suture line, according to Ambriz González et al.[11] Fibrin glue has been shown in large series by Gopal et al. to decrease the incidence of fistula development, although it does not remove the risk of recurrence.[12]

From either a pool of plasma or a single donor’s, fibrin sealants may be generated. There is a substantial risk of transmission of bloodborne illnesses related to the use of commercially available sealants.[10] These sealants may also cause allergic reactions and bleeding, among other issues. Autologous blood is an excellent source of fibrin because it reduces the risk of severe side effects. For the repair of the UCF, Kajbafzadeh et al. advocated the use of a single-donor fibrin sealant.[10] They only utilized plasma from a single donor for the trial to reduce the risk of problems. Cryoprecipitate, centrifugation, and incubation were all stages in the preparation procedure. Neither a urethral fistula nor stricture was reported by them.

In this study, we utilized PRF as a supportive extramaterial for UCF repair. Angiogenesis and wound healing are enhanced by the use of PRF, a novel platelet concentrate. It prevents infections by boosting the immune system’s response. PRF increases collagen production and the capacity of fibroblasts to proliferate.[22] It is also rich in several platelet-derived growth factors, vascular endothelial growth factor, and Fibroblast Growth Factor b (FGF-b).[16]

During distal hypospadias surgery, Guinot et al., performed a randomized experiment to examine the effect of PRF on urethroplasty coverage.[23] Two of the 33 individuals studied had fistulas, according to their results. Distal hypospadias have a high rate of complications, and this approach was shown to be safe by comparing it to the rate of complications published in the literature.[24,25] There were no adverse effects or skin reactions found throughout the study. They concluded that they were unable to establish the advantage of PRF above standard covering methods for the distal hypospadias. In another randomized trial, Mahmoud et al. mentioned that patients treated with tubularized incised plate urethroplasty with platelet-rich plasma coverage layer (Group A) were associated with significantly fewer complications than those treated with ventral dartos flap (Group B). Nine patients in Group A (10%) and 12 in Group B (13.3%) had UCFs. Group A had no superficial wound infections, but Group B had six. Meatal and urethral stricture were documented in each group, and all of them were treated with conservative measures.[26]

Choukroun et al. claimed that PRF was first applied in oral and reconstructive surgery.[16] Compared to other fibrin sealants, PRF offers a number of benefits. Prepared entirely from the patient’s own serum, the PRF is free of infection and allergy risks since it does not involve biochemical blood processing. In addition to these benefits, the PRF is also inexpensive because it only requires 5 mL of blood to make.[16] The fibrin mesh of the PRF has been proven in experiments to be a trap for cytokines. As endothelial and fibroblast cells migrate across the three-dimensional structure of these PRF patches, angiogenesis and fibrin reorganization occur.[27] Fibrin allows the cell differentiation, adhesion, migration, and recruitment of the various cell types needed for tissue healing.[28] PRF has high mechanical strength and provides extended release of growth factors and protection of these factors against proteolysis.[29] In animal studies, PRF enhances cartilage regeneration in rabbit knees by providing favorable circumstances for cell migration and cell proliferation.[30] Animal models, on the other hand, should be interpreted carefully. A species’ blood composition and clotting processes have an enormous impact on PRF’s performance.[31] Those with hypospadias had much lower levels of the growth factor epidermal than males with a normal penis, according to research conducted by El Galley et al.[32] As a result, PRF creates a fibrin membrane at the surgical site that might release cytokines and growth factors that may be advantageous, at least in the early stages of recovery.

CONCLUSION

UCF surgery may benefit from the use of PRF as a supportive tissue that promotes wound healing, angiogenesis, and tissue restoration. We believe that the use of PRF as a new approach for UCF repair should be investigated further through clinical studies.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.