Optimizing neourethral coverage in urethroplasty for hypospadias with tunica vaginalis versus dartos fascia: A systematic review and meta-analysis

ABSTRACT

Objectives:

Hypospadias repair requires second-layer coverage to minimize complications. This study compares tunica vaginalis flap (TVF) and dartos fascia (DF) as second-layer materials in tubularized incised plate (TIP) urethroplasty, focusing on postoperative complications, functional outcomes, and cosmetic results to determine the superior option.

Materials and Methods:

Comparative studies on TVF versus DF in TIP urethroplasty were identified through five databases (PubMed, Scopus, ScienceDirect, Cochrane Library, and Google Scholar; January 2015–January 2025). A modified PICO framework guided the search, and risk of bias (RoB) was assessed using RoB 2 and ROBINS-I. Meta-analysis evaluated postoperative complications.

Results:

Ten studies comparing TVF and DF in TIP hypospadias repair were included in the study. TVF significantly reduced the risk of urethrocutaneous fistula (UCF) (risk ratios [RR] = 0.27; 95% confidence interval [CI]: 0.16–0.46; P < 0.00001), wound infection (RR = 0.40; 95% CI: 0.24–0.66; P = 0.0003), wound dehiscence (RR = 0.61; 95% CI: 0.38–0.98; P = 0.04), and penile skin necrosis (RR = 0.22; 95% CI: 0.06–0.73; P = 0.01), with minimal heterogeneity. No significant differences were found for meatal stenosis, urethral stricture, glans dehiscence, residual chordee, or torsion. Cosmetic outcomes slightly favored TVF, although assessment heterogeneity limited definitive conclusions. Functional outcomes were comparable between groups.

Conclusion:

Findings from this meta-analysis suggest that the tunica vaginalis flap may be associated with lower rates of selected postoperative complications, particularly UCF, wound infection, wound dehiscence, and penile skin necrosis, compared with dartos fascia in TIP hypospadias repair, whereas cosmetic and functional outcomes appear comparable between the two techniques.

INTRODUCTION

Hypospadias ranks as the second-most common congenital anomaly among males and is the leading congenital malformation of the penis [1]. It occurs when the urethra does not develop properly, resulting in a misplaced meatus. This condition is typically identified through physical signs such as an abnormally located urethral opening, a downward bend of the penis (chordee), and a foreskin that forms a hood on the top rather than fully covering the tip [2]. The main goals of hypospadias surgery are to straighten the penis, establish a properly sized and positioned urethral opening at the apex of the glans, reshape the glans into a natural form, and provide either a circumcised appearance or, if desired, a fully developed and retractable foreskin, while achieving a satisfactory cosmetic outcome [3].

The tubularized incised plate (TIP) urethroplasty, or Snodgrass procedure, was introduced by Dr. Warren Snodgrass in 1994. It has been the procedure of choice for distal and midshaft hypospadias, but is now applied to almost all types of hypospadias. The technique is simple to perform and is known for giving good cosmetic appearance and functional results [4]. Common postoperative complications following hypospadias surgery include immediate issues such as edema and minor bleeding, whereas more serious long-term problems may involve urethrocutaneous fistulas (UCF), meatal stenosis, urethral diverticulum, and erectile dysfunction. Among these, UCF stands as the most frequently reported complication and often requires additional surgical intervention [1,5]. A well-vascularized second-layer flap is very important in hypospadias surgery because it helps protect and support the neourethra. Its primary function is to significantly reduce the risk of UCF formation. This vascularized tissue layer enhances healing by supplying additional blood flow, promoting tissue regeneration, and improving suture line stability. It also acts as a mechanical protective layer separating the neourethra from the overlying skin, minimizing the tension, and shielding the repair from external forces [6].

The two most commonly used second-layer flaps in TIP urethroplasty (TIPU) for hypospadias are the dartos fascia (DF) and the tunica vaginalis flap (TVF). Dartos fascia, commonly taken from the shaft of the penis, foreskin, or scrotum, is frequently selected for hypospadias repair due to its accessibility and widespread use among surgeons. However, aggressive dissection to obtain a larger flap can reduce blood flow to the penile skin, potentially causing complications such as penile torsion or damage to the prepuce. This risk increases particularly when the dorsal dartos is deeply separated from the overlying skin, as this can compromise the blood supply and raise the likelihood of skin-related complications. The tunica vaginalis flap, taken from the testicular covering, provides rich and consistent vascularized tissue, making it especially valuable in proximal or repeat hypospadias surgeries where local tissue is limited. It has the advantage of being unaffected by penile skin conditions and provides a large, reliable flap to cover the urethral repair as well as fistula repair, resulting in excellent surgical outcomes. However, the procedure is more technically demanding and carries a small risk of injury to nearby testicular structures [5,6,7]. In addition, the selection of either flap is guided by the surgeon’s experience and preference, rather than being supported by robust scientific data [8].

The most recent meta-analysis comparing TVF and DF as second-layer flaps in TIPU was published by Yang et al. and included six comparative studies. Their findings indicated that TVF was superior to DF in reducing overall postoperative complications, particularly UCF and prepuce-associated complications [7]. Our updated study expands upon this by including nine comparative studies published between 2015 and 2025. In addition, this is the first study to integrate an evaluation of cosmetic outcomes through a systematic review, due to insufficient standardized data for quantitative analysis. This broader approach offers a more comprehensive understanding of both surgical efficacy and esthetic outcomes in TIPU. The objective of this study is to assess the surgical outcomes, particularly the incidence of postoperative complications, functional results, and cosmetic outcomes, of TVF versus DF as second-layer coverage in TIPU for hypospadias repair.

MATERIALS AND METHODS

Ethics statement

This study was a systematic review and meta-analysis that relies solely on existing published research. No new experiments involving human participants or animals were conducted by the authors. Consequently, approval from an institutional review board and informed consent were not necessary.

Study design and search strategies

A meta-analysis and systematic review were conducted to analyze the comparison of the tunica vaginalis flap versus dartos fascia in hypospadias repair using TIP. The studies included in this review were retrieved through a literature search of PubMed, Scopus, ScienceDirect, Cochrane Library, and Google Scholar from January 2015 to January 2025. The study strictly followed the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 and was officially registered on PROSPERO CRD420251158791 [8]. The search strategy used was “hypospadias repair,” “hypospadias surgery,” “tubularized incised plate,” “TIP,” “Snodgrass repair,” “tunica vaginalis,” and “dartos.” The search was limited to articles published in English.

The scope of this study was restricted to randomized controlled trials (RCTs), quasi-RCTs, non-RCTs, retrospective, prospective, or concurrent cohort study designs that explore the postoperative complication of tunica gaginalis flap versus dartos fascia in hypospadias repair using TIP, as stated in the PICO framework [Figure 1].

Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram illustrating the study selection process

Complications included UCF, meatal or urethral stenosis, and wound-related issues such as dehiscence, infection, or meatal retraction. Prepuce-related complications included preputial fistula, separation of the prepuce (dehiscence), skin necrosis, or phimosis. In addition, testicular complications such as ascent, torsion, infection, or atrophy were noted, along with the occurrence of urinary tract infections. Functional outcomes assessed included the direction of the urinary stream, peak flow rate, total voided volume, average flow rate, duration of voiding, the shape of the flow curve, and the amount of residual urine. Cosmetic outcomes were evaluated using the Hypospadias Objective Scoring Evaluation (HOSE) score, the Pediatric Penile Perception Score (PPPS), and the Hypospadias Objective Penile Evaluation (HOPE) score [9,10,11].

HOSE is a scoring system for hypospadias surgery that looks at the position and shape of the urethral opening, urinary flow, penis straightness during erection, and whether urethral fistulas are present [9]. PPPS is a validated tool for evaluating cosmetic results following hypospadias surgery. It takes into account the perspectives of the patient, parents, and independent urologists, focusing on the appearance of the meatus, glans, shaft, and overall penis [10]. The HOPE score is a well-established tool that objectively measures the cosmetic appearance of the penis after hypospadias surgery. It assesses the position and shape of the meatus, glans shape, penile skin, and penile alignment [11]. The main outcomes of interest were postoperative complications, whereas secondary outcomes included both functional and cosmetic assessments.

Eligibility criteria

The inclusion criteria for the present study were based on the Population, Intervention, Comparison, Outcome, and Study Design framework:

• Pediatric (aged below 18) diagnosed with hypospadias and received TIPU

• Studies that compare the tunica vaginalis flap versus the dartos fascia

• Studies were RCTs, quasi-RCTs, non-RCTs, retrospective, prospective, or concurrent cohort study design

• Studies that report the incidence of postoperative complications with/without functional or cosmetic outcome

• Publications in the English language.

The exclusion criteria were insufficient data reporting or unavailable full-text articles, >18-year-old respondents, studies including patients with redo or previously operated hypospadias, reviews, expert opinions, comments, studies that do not report on relevant outcomes, letters to the editor, studies on animals, conference reports, and proceeding abstracts conferences.

Data extraction

Three reviewers independently carried out the process of data extraction. The data extraction included the author’s name, year of publication, country of origin, design of study, population mean age, total population, type of hypospadias, follow-up time, incidence of postoperative complications, perioperative use of antibiotics, functional and cosmetic outcomes, and conclusion.

Quality assessment

Study quality was examined using two assessment tools based on study design. RCTs were evaluated using the RoB 2 tool, which examines potential biases in randomization, deviations from intended interventions, missing outcome data, outcome measurement, and selective reporting. Nonrandomized studies, including quasi-RCTs, non-RCTs, and cohort studies, were assessed using the ROBINS-I tool.

This tool allowed for the evaluation of biases related to confounding factors, participant selection, intervention classification, deviations from planned interventions, incomplete data, and outcome assessment and reporting.

Meta-analysis

Quantitative data were collected using the Cochrane Collaboration’s Review Manager (RevMan) version 5.4; The Cochrane Collaboration, Copenhagen, Denmark. For continuous outcomes, results were reported as mean differences with 95% confidence intervals (CI), whereas dichotomous outcomes (events/total) were analyzed using risk ratios (RR) with 95% CI. P < 0.05 was considered statistically significant. Heterogeneity between studies was assessed using I², with values above 50% considered high, 26%–50% moderate, and below 26% low.

RESULTS

Study selection and characteristics of the included studies

According to the PRISMA diagram, the study identification process began with a comprehensive literature search across PubMed (n = 113), Scopus (n = 129), Science Direct (n = 540), Cochrane Library (n = 35), and Google Scholar (n = 840), yielding a total of 1657 records. At the initial screening stage, 184 duplicate entries were eliminated, and 1427 records were removed for being off-topic or inaccessible, leaving 46 records for further screening. Of these, 35 records were excluded for failing to meet the inclusion criteria. Eleven reports were sought for retrieval, all of which were successfully accessed. At the eligibility assessment, 11 reports were evaluated, and 1 was excluded for not reporting the relevant outcome. Consequently, 10 studies were incorporated into the systematic review and meta-analysis [Figure 1].

Each included study is cited, and its key characteristics are summarized in Table 1. These characteristics include the study author and year of publication, country, study design, and mean patient age. The Table 1 also presents the total study population, hypospadias type, follow-up duration, postoperative complications, and functional and cosmetic outcomes.

Table 1.

Characteristics of the included studies

Study identification	Population				Intervention				Comparison and outcomes
Author (year)	Country	Design of Study	Age (mean±SD)	Total	Hypospadias type	Intervention	Control	Follow-up (month)	Postoperative complication	Functional and cosmetic outcomes
Ramez et al., 2025 [5]	Egypt	Prospective RCT	NA Median Dartos fap group=4 TVF group=4	Dartos fap group=43 TVF group=41 Total=84	Distal, midshaft and coronal	TVF group	DF group	3 months and 12 months	DF  Meatal stenosis 3  Stricture 1  Bleeding 1  UCF 9  Testicular ascent 0 TVF  Meatal stenosis 2  Tourque 1  Edema 3  Pain 2  UCF 2  Testicular ascent 3	Cosmetic outcome using PPPS and HOSE DF  Total PPPS score 14  Total HOSE score 15 TVF  Total PPPS score 15  Total HOSE score 15
Ranjay et al., 2024 [8]	India	Prospective comparative cohort study	The mean age was 4.690909 years, with a SD of 3.151265	Group A (TVF)=30 Group B (Dartos)=30 Total=60	Distal, mid penile and Proxiaml	TVF group	Dartos	1 month	DF  Wound infection 14  Wound dehiscence 12  Residual torsion 1  Residual chordee 2  UCF 11 TVF  Wound Infection 6  Wound dehiscence 7  Residual torsion 1  Residual chordee 2  UCF 1	NA
Mamun et al., 2024 [12]	Bangladesh	Quasi- experimental study	Group A=5.8±2.1 years Group B=4.9±2.1 years	Group A (TVF)=21 Group B (DF)=20 Total 41	Coronal, distal penile and subcoronal	TVF	DF	5 and 10 postoperative days 1 months 3 months 6 months	DF  Wound infection 10  Penile skin necrosis 4  Wound dehiscence 7  UCF 9  Meatal stenosis 1	Assessment of cosmetic DF  Acceptable 40%  Good 50%  Poor 10%
									TVF  Wound infection 3  Penile skin necrosis 1  Wound dehiscence 4  UCF 3  Meatal Stenosis 0	TVF  Acceptable 28.6%  Good 71.4%  Poor 0% Urinary flow DF Unsatisfactory 4 TVF Unsatisfactory 3
Pal et al., 2023 [13]	India	Prospective cohort study	NA	Group 1 (DF)=30 Group 2 (TVF)=30 Total=60	Distal Penile	TVF group	DF	6 Week postoperative	DF  Glans dehiscence 1  Scrotal Hematoma 1  Urethral stricture 1  Urehtrocutaneousfistula 2 TVF  Glans Dehiscence 1  Scrotal Hematoma 1  UCF 2	NA
Ahmed et al., 2022 [14]	Yemen	Retrospectively	The mean age was 56.38±47.83 (22.50–94.5) months	TVF=11 Dartos Fasia=5 Total=16	Middle, Proximal, penoscortal	TVF group	Dartos	24 months	DF  Fistula 1  UTI 0  Pain in micturition 1 TVF  Fistula 1  UTI 3  Pain in micturition 2	NA
Sengol et al., 2021 [15]	India	Nonrandomized experimental (experimental) study	NA Most of the patients who presented were <5 years of age (72.2%)	DF=42 Tunica Vaginalis=38 Spongioplasty=17 Total=97	Distal penile, mid penile, proximal penile	TVF group	DF	One year	DF  Fistula 3  Meatal stenosis 0  Skin Necrosis 1  Scrotal edema 0  Wound dehiscence 1	At the end of one-year follow-up, all the patients including pa- tients who had complications were functionally (on the basis of uroflowmetry) and cosmetically normal
									TVF  Fistula 1  Meatal stenosis 0  Skin necrosis 0  Scrotal edema 1  Wound dehiscence 0
Kurbet et al., 2018 [16]	India	RCT	years Preputial dartos=4.17 Tunica Vaginalis=5.25	Group A (preputial DF)=20 Group B (TV vascular cover)=20 Total=40	Distal, mid-penile, proximal	TVF group	Preputial dartos	6 months after surgery	DF  Meatal stenosis 2  Mild torsion of testis 1  UCF 2  Stricture urethra 1 TVF  Meatal stenosis 2  UCF 0  Stricture urethra 1	NA
Gajbhiye et al., 2018 [17]	India	Non-RCT	Group A=20 months (range: 18–36 months) Group B=22 months (range: 18–52 months)	Group A (TVF)=24 Group B (DF)=24 Total=48	Distal penile and mid penile	TVF group	DF	Follow-up was from 6 to 18 months in both the groups	DF  Fistula 3  Localised superficial necrosis of ventral penile skin 3 TVFS   uperficial wound dehiscence 1  Fistula 0	NA
Patel et al., 2018 [18]	India	RCT	Mean age: 4.69±3.15 years	Group A (TVF)=27 Group B (DF)=28 Total=55	Distal, mid penile, proximal penile	TVF group	DF	1 month	DF  UCF 12  Wound infection 14  Skin necrosis 5  Wound dehiscence 12  Residual chordee 2  Residual torsion 1	NA
									TVF  UCF 5  Wound infection 6  Skin necrosis 1  Wound dehiscence 7  Residual chordee 2  Residual torsion 1
Basavaraju and Balaji, 2017 [19]	India	Cohort	Group A (TVF)=3.5 Group B (dorsal dartos)=3 Group C (Ventral dartos)=4	Group A (TVF)=26 Group B (dorsal dartos )=36 Group C (ventral dartos)=21 Total=83	Distal, mid penile, proximal, chordee	TVF group	DF	Follow-up period ranged from 6 months to 3 years	DF  Fistula 11  Glans Breakdown 3  Meatal stenosis 1 TVF  Fistula 0  Glans Breakdown 0  Meatal stenosis 0	NA

TVF: Tunica vaginalis flap, DF: Dartos fascia, NA: Not available, UCF: Urethrocutaneous fistula, RCT: Randomized controlled trial, PPPS: Paediatric penile perception score, HOSE: Hypospadias objective scoring evaluation, SD: Standard devaition

Risk of bias

The quality of evidence for RCTs was assessed using the RoB 2.0 tool, and all three RCTs showed a low RoB. Nonrandomized studies, including quasi-RCTs and cohort studies, were evaluated with the ROBINS-I tool. Of these, five studies had a low RoB, and two had a moderate risk [Figure 2].

Figure 2.

Risk of bias assessment of the included studies using (a) the Cochrane Risk of Bias 2 tool for randomized studies and (b) the ROBINS-I tool for nonrandomized studies

TUNICA VAGINALIS FLAP VERSUS DARTOS FASCIA IN HYPOSPADIAS REPAIR USING TUBULARIZED INCISED PLATE

Urethrocutaneous fistula

This meta-analysis of 10 studies demonstrates that the tunica vaginalis flap (TVF) significantly reduces the risk of UCF compared to dartos fascia (DF) in hypospadias repair using TIP. The pooled RR was 0.27 (95% CI: 0.16–0.46; P < 0.00001), indicating a 73% lower risk of fistula in the TVF group. Heterogeneity across studies was negligible (χ² = 5.13, df = 9; P = 0.82; I² = 0%), suggesting consistent findings. Overall, TVF appears to be a more effective option than DF for minimizing the risk of UCF following hypospadias repair. Small-study effects were assessed using Egger’s regression test, and the regression intercept was not statistically significant (P > 0.05), indicating no funnel plot asymmetry and no evidence of significant publication bias. To further explore this, a trim-and-fill analysis using a fixed-effects model was performed, estimating that two studies may be missing on the right side of the funnel plot (SE = 2.20). After imputing these potentially missing studies, the adjusted overall effect size remained statistically significant (log RR = −0.9984, SE = 0.2514, P < 0.0001), with a 95% CI from −1.4912 to −0.5057, corresponding to a RR of approximately 0.37 (95% CI: 0.23–0.60) [Figure 3a].

Figure 3.

Forest plots comparing tunica vaginalis flap versus dartos fascia as second-layer coverage in tubularized incised plate hypospadias repair for selected postoperative complications, including (a) urethrocutaneous fistula, (b) wound infection, (c) wound dehiscence, and (d) penile skin necrosis

Wound infections

This meta-analysis of three studies demonstrates that the tunica vaginalis flap (TVF) significantly reduces the risk of wound infection compared to the dartos fascia (DF) in hypospadias repair using TIP. The pooled RR was 0.40 (95% CI: 0.24–0.66; P = 0.0003), indicating a 63% lower risk of wound infection in the TVF group. Heterogeneity across studies was negligible (χ² = 0.43, df = 2; P = 0.80; I² = 0%), suggesting consistent findings. Overall, TVF appears to be a more effective option than DF for reducing postoperative wound infection in hypospadias repair [Figure 3b].

Wound dehiscence

This meta-analysis of five studies demonstrates that the tunica vaginalis flap (TVF) significantly reduces the risk of wound dehiscence compared to dartos fascia (DF) in hypospadias repair using TIP. The pooled RR was 0.61 (95% CI: 0.38–0.98; P = 0.04), indicating a 39% lower risk in the TVF group. Heterogeneity across studies was negligible (χ² = 1.14, df = 3; P = 0.89; I² = 0%), suggesting consistent findings [Figure 3c].

Penile skin necrosis

This meta-analysis of four studies demonstrates that the tunica vaginalis flap (TVF) significantly reduces the risk of penile skin necrosis compared to dartos fascia (DF) in hypospadias repair using TIP. The pooled RR was 0.22 (95% CI: 0.06–0.73; P = 0.01), indicating a 78% lower risk of penile skin necrosis in the TVF group. Heterogeneity across studies was minimal (χ² = 0.19, df = 2; P = 0.98; I² = 0%), suggesting that the findings are consistent across the included studies. These results support the use of TVF as a more favorable way to reduce the incidence of penile skin necrosis following hypospadias surgery [Figure 3d].

Meatal stenosis

Analysis of four studies indicates no statistically significant difference in the risk of meatal stenosis between TVF and DF in hypospadias repair using TIP. The pooled RR was 0.70 (95% CI: 0.24–2.09; P = 0.53), indicating a nonsignificant 30% lower risk in the TVF group. The test for heterogeneity was minimal (χ² = 0.38, df = 3; P = 0.94; I² = 0%), suggesting consistent findings across studies. Overall, there is insufficient evidence to conclude a superiority of either technique regarding the prevention of meatal stenosis [Figure 4a].

Figure 4.

Forest plots comparing tunica vaginalis flap versus dartos fascia as second-layer coverage in tubularized incised plate hypospadias repair for additional postoperative complications, including (a) meatal stenosis, (b) urethral stricture, (c) glans dehiscence, (d) residual chordee, and (e) residual torsion

Urethral stricture

Pooled results from three studies showed no significant difference in the risk of urethral stricture between TVF and DF using TIP. The pooled RR was 0.51 (95% CI: 0.10–2.70; P = 0.43), suggesting a nonsignificant 49% lower risk in the TVF group. Heterogeneity was negligible (χ² = 0.36, df = 2; P = 0.83; I² = 0%), indicating consistent results across studies. These findings suggest no clear advantage of TVF over DF in reducing the incidence of urethral stricture following hypospadias repair [Figure 4b].

Glans dehiscence

Analysis of two studies found no notable difference between TVF and DF in reducing the risk of glans dehiscence. The pooled RR was 0.52 (95% CI: 0.07–3.64; P = 0.51), indicating a nonsignificant 48% lower risk in the TVF group, with a wide CI. Heterogeneity was minimal (χ² = 0.35, df = 1; P = 0.56; I² = 0%), indicating consistent results. Overall, there is no conclusive evidence to support the superiority of either technique for preventing glans dehiscence [Figure 4c].

Residual chordee and torsion

This meta-analysis of two studies, Patel et al. (2018) and Ranjay et al. (2024), found no significant difference between TVF and DF in preventing residual chordee and residual torsion [8,18]. For residual chordee, the pooled RR was close to 1 with a wide CI, indicating no significant effect, and for residual torsion, the pooled RR similarly showed no significant difference. Heterogeneity was minimal for both outcomes (I² = 0%), indicating consistent results across studies. Overall, there is no conclusive evidence to support the superiority of either technique in preventing these postoperative complications [Figure 4d and e].

Cosmetic outcome

Three studies reported on cosmetic outcomes following the use of TVF versus DF in hypospadias repair with the TIP technique. One study assessed cosmetic outcomes using the PPPS and HOSE scores. The other two studies mentioned cosmetic assessment but did not specify the method or scoring system used. Ramez et al. reported no significant difference between the two groups in overall PPPS scores (P = 0.076). However, the total HOSE scores were notably greater in the TVF group than those in the DF group (P = 0.024), indicating a better cosmetic outcome [5]. Furthermore, Mamun et al. found that cosmetic outcomes were more favorable in the tunica vaginalis flap group (Group A), with 71.4% achieving good results. In contrast, only 50% of the dartos fascia group (Group B) had good outcomes, whereas 40% were rated as acceptable and 10% as poor. Notably, no poor outcomes were observed in Group A [12]. Moreover, Sengol et al. concluded that by the end of a 1-year follow-up, all patients, including those who had experienced complications, demonstrated a normal cosmetic appearance [15].

Functional outcome

Two studies reported on functional outcomes following the use of TVF versus DF in hypospadias repair with the TIP technique. Mamun et al. found that urinary flow was better in the tunica vaginalis flap group (Group A), with 85.7% of patients reporting satisfactory results, compared to 80% in the dartos fascia group (Group B). However, this difference was not statistically significant (P = 0.697) [12]. Furthermore, Sengol et al. observed that after a 1-year follow-up period, all patients demonstrated normal functional outcomes as assessed through uroflowmetry [15].

DISCUSSION

This meta-analysis found that using a tunica vaginalis flap (TVF) is associated with reducing the risk of common complications such as UCF, wound infection, wound dehiscence, and penile skin necrosis, which highlights its potential benefits in minimizing some of the most frequent and serious postoperative issues. On the other hand, there was no clear difference between TVF and DF when it came to preventing meatal stenosis, urethral stricture, glans dehiscence, residual chordee, and residual torsion. This suggests that while TVF offers certain protective benefits, its superiority may not extend to all types of complications. Collectively, these results support the use of TVF as a potentially safer alternative to DF for reducing key surgical complications in hypospadias repair. Using extra layers of tissue interposed between the reconstructed urethra and the skin during surgery has been shown to lower postoperative complications, particularly UCF after hypospadias repair. These protective layers can originate from the corpus spongiosum, flaps of deepithelialized skin such as foreskin, dartos tissue, tunica vaginalis, or grafts from the inside of the mouth or bladder lining [20]. The two most commonly used second-layer flaps in TIPU for hypospadias are the DF and the TVF [7].

The findings of this meta-analysis, which show that complications such as wound infections, wound dehiscence, and penile skin necrosis were significantly reduced in surgical procedures using TVF compared to DF, may be attributed to the histological advantages of the TVF. TVF is a valuable option in urethral reconstruction. It is highly vascularized, thin, flexible, and expandable. TVF provides richly vascularized tissue that supports angiogenesis and tissue regeneration, which are key factors in reinforcing the urethroplasty site and preventing urine leakage that could lead to fistula formation [21]. This rich vascularization is due to its independent blood supply, which ensures adequate vascular support without affecting circulation to the outer foreskin [22]. However, the low usage of TVF may be due to its more complex technique, in which the testicle is moved into the surgical area through a penile incision following total removal of the penile skin, although this step is not always required, especially in cases of distal hypospadias without chordee. In such cases, an extra scrotal incision is performed, and the flap is routed through the scrotal tissue to access the neourethra, which can increase the risk of complications. The main concern is damaging the blood vessels or ducts of the testicle [6]. Cautious scrotal dissection and good control of bleeding can help prevent scrotal complications [23].

On the other hand, while the artos fascia is commonly used, it does have some disadvantages. Separating the dartos tissue from the preputial skin and penile shaft requires skill, as performing this too aggressively can lead to vascular failure and necrosis in flaps made from the preputium and dorsal skin. If the preputial skin becomes devascularized during the dissection of the artos fascia, this may lead to necrosis of the ventral skin, increasing the incidence of UCF [24,25]. Warren T. Snodgrass, who introduced the TIPU (or Snodgrass procedure), stated that he creates a ventral artos fascia to protect the neourethra, using tunica vaginalis when this tissue is unavailable [26]. This means that if the artos fascia is unavailable, the tunica vaginalis can be used as an alternative and vice versa.

Infection-related complications, such as wound infections, may be influenced by perioperative and postoperative antibiotic use. In this meta-analysis, only 7 out of 10 studies reported their antibiotic protocols, whereas 3 provided no information. Wound infections are common after urethroplasty and can lead to surgical failure or later complications [27]. Baillargeon et al. (2014) found a low incidence of infections in hypospadias repair and questioned the need for preoperative IV antibiotics, suggesting that more research is needed to determine appropriate antibiotic use.[28] However, this contrasts with other systematic reviews that found no clear benefit of postoperative antibiotics in reducing complications. The current evidence remains low-quality, highlighting the need for well-designed randomized trials to clarify the role of antibiotic prophylaxis in preventing infections, stricture recurrence, and improving patient outcomes [28].

In a study made by Neheman et al., they reported that more than 80% of boys who have hypospadias repair get great cosmetic results. However, over 10% of them need extra procedures just to improve the appearance. This shows that cosmetic outcomes play a key role as well [29]. Tariq et al. found that the TIPU technique had the highest average HOSE scores in their study. This technique is effective for distal hypospadias, given its ability to create a natural-appearing urethral meatus and reduce complications [30]. However, there is still limited literature on the cosmetic outcomes comparing dartos and TVF in hypospadias repair with the TIP technique.

Several studies support the superiority of TVF over DF as a second-layer coverage in hypospadias repair. Ramez et al. reported that TVF significantly reduces the incidence of fistula formation compared to DF, although it requires slightly longer operative time [5]. Similarly, Ranjay et al. (2024) observed a greater incidence of fistula formation and skin necrosis in the DF group, suggesting that TVF should be used as a protective second layer [8]. Mamun et al. concluded that TVF provides better postoperative outcomes for distal penile hypospadias undergoing TIPU [12]. Patel et al. reported increased rates of fistulas and skin necrosis with the artos fascia compared to TVF, demonstrating the advantage of TVF and recommending it as a waterproofing second layer in hypospadias repair [18]. Basavaraju and Balaji further supported TVF as a superior vascular cover in primary hypospadias repair [19].

However, not all studies unanimously favor the TVF. For example, Pal et al. found no statistically significant differences in overall complications or UCF rates between scrotal dartos and TVF, suggesting that both can be equally effective in certain cases [13]. Similarly, Sengol et al. emphasized that the best choice of flap depends on the location of the hypospadias; it is recommended to use the artos fascia (DF) for distal cases and TVF for midshaft or proximal cases due to its favorable outcomes in those settings [15]. Supporting this, Ahmed et al. noted that TVF serves as a practical and effective interpositional cover in cases of penoscrotal and proximal hypospadias, particularly when accompanied by severe chordee [14]. There are also studies that do not claim TVF to be superior or inferior but rather consider it a viable alternative to DF. For instance, Kurbet et al. found that TVF can serve as a reliable substitute for the preputial artos fascia for primary hypospadias repair with the TIP technique [16]. Similarly, Gajbhiye et al. reported that TVF is a dependable alternative to the DF in primary hypospadias repair [17]. Collectively, while the evidence leans toward the superiority of TVF in reducing complications, its longer operative time and specific case suitability should be carefully considered in surgical decision-making.

The results of this meta-analysis, obtained from this recent study, are largely consistent with the research conducted by Yang et al., in which a direct comparison was made between DF and TVF in TIPU. The study primarily evaluated several postoperative outcomes, focusing on the efficacy of these techniques in preventing complications. The meta-analysis reported that the TVF demonstrated superior results compared to the DF. In the study by Yang et al., significant differences were observed in total complications, UCF, and prepuce-related complications [7]. However, in our meta-analysis, we found significant reductions not only in UCF but also in wound infection, wound dehiscence, and penile skin necrosis. Furthermore, Yang et al. conducted their meta-analysis by analyzing total complications [7]. This approach was not adopted in our study because, in several included studies, the total number of complications exceeded the total population. This indicates that some patients experienced more than one complication, which could introduce bias if total complications were analyzed collectively. Therefore, we performed separate analyses for each type of complication, as we believe this approach provides a more accurate and fair comparison between similar outcomes.

Despite these promising findings, this meta-analysis did not provide detailed information regarding the functional and cosmetic outcomes associated with each flap. This represents a notable gap in the current literature, as both functional outcomes, including urinary stream quality and voiding efficiency, and cosmetic outcomes, such as penile appearance and patient satisfaction, are essential components in the comprehensive evaluation of hypospadias repair success. Even though we conducted a systematic review to analyze these outcomes, the data could not be included in the meta-analysis because of incomplete reporting and inconsistencies in evaluation methods across studies. The lack of standardized and complete data highlights the need for further research to assess the long-term functional and esthetic implications of TVF compared to the DF.

Strength

However, our systematic review also examined cosmetic and functional outcomes across various surgical techniques. The results from multiple studies assessing cosmetic outcomes using different scoring systems were heterogeneous. Some studies reported no significant differences, while others, such as those employing the HOSE, indicated that the TVF group achieved better cosmetic outcomes compared to the DF group. Regarding functional outcomes, the evidence remains inconclusive due to the variability of results reported across studies. Therefore, no definitive conclusions can yet be drawn about the comparative functional efficacy of these techniques. Based on the results of this meta-analysis, it can be used as a reference for future studies, indicating that surgery using the tunica vaginalis flap (TVF) technique offers promising outcomes by reducing various postoperative complications and also shows potential in delivering favorable cosmetic and functional results.

Limitations

This meta-analysis has some limitations. First, follow-up periods varied widely among the included studies, ranging from 1 to 36 months. While some studies provided longer follow-up, several included only short-term follow-up of 1–3 months, which may be insufficient to capture certain complications. Consequently, variability in follow-up duration may influence the detection of complications across studies, and the pooled results should therefore be interpreted with caution. Second, the included studies involved surgeons with different levels of skill and experience, which could influence surgical outcomes and introduce performance bias. Third, the majority of included studies were nonrandomized and often had small sample sizes, which makes it harder to draw strong conclusions. Fourth, there was notable heterogeneity in hypospadias location, including distal, midshaft, and proximal types, which are known to significantly influence postoperative complication rates. Although subgroup analysis based on hypospadias location would be clinically meaningful, such analysis was not feasible because the included studies did not consistently report outcome data stratified by hypospadias severity or location. Consequently, the pooling of heterogeneous hypospadias types may introduce bias and should be considered when interpreting the results. Fifth, although subgroup analyses based on hypospadias severity and artos fascia subtype would be clinically informative, such analyses were not feasible because the included studies reported outcome data only as comparisons between tunica vaginalis flap and dartos fascia, without further stratification. As a result, insufficient stratified data were available to permit meaningful subgroup analyses for these factors. These factors, combined with differences in study design and reporting standards, may contribute to variability in the outcomes and limit the overall conclusiveness of the findings.

In addition, although several studies reported cosmetic and functional outcomes following the use of tunica vaginalis flap versus dartos fascia in TIP hypospadias repair, the assessment methods and reporting were limited and heterogeneous. Cosmetic outcomes were evaluated using different approaches, with only one study employing standardized scoring systems such as the PPPS and the HOSE, whereas other studies did not clearly specify the assessment tools used. Similarly, functional outcomes were reported in only a small number of studies and were assessed using different measures, including subjective satisfaction and uroflowmetry, with limited statistical power to detect meaningful differences between groups. This heterogeneity and limited reporting precluded quantitative synthesis and may introduce bias in outcome interpretation.

Furthermore, perioperative antibiotic protocols were inconsistently reported across the included studies, with some studies not specifying antibiotic use and others lacking details on the agents or regimens employed. Given the known impact of perioperative antibiotics on surgical site infection rates, this variability may act as a confounding factor for infection-related outcomes and limits definitive interpretation.

Future recommendation

Further research should include long-term follow-up to clarify outcomes such as cosmetic results, functional outcomes, and overall patient satisfaction. It is also important to use standardized evaluation tools such as HOSE and PPPS for cosmetic outcomes and validated objective scoring systems for functional assessments. Researchers should also clearly separate results based on the type and location of hypospadias, such as distal, midshaft, or proximal, since outcomes can differ. In addition, future research should explore more flap options and new materials that may improve healing. Promising options include biologic adjuncts for urethral coverage, such as acellular matrix, tissue adhesives, and platelet-rich plasma or fibrin, which could help reduce complications and enhance surgical success.

CONCLUSION

This meta-analysis suggests that the tunica vaginalis flap (TVF) may be associated with lower rates of selected postoperative complications, particularly UCF, wound infection, wound dehiscence, and penile skin necrosis, compared with dartos fascia (DF) in TIP hypospadias repair. No statistically significant differences were observed for other complications, including meatal stenosis, urethral stricture, glans dehiscence, residual chordee, and residual torsion, indicating that while TVF may reduce certain complications, it does not improve all postoperative outcomes. Although TVF showed a trend toward improved cosmetic outcomes, heterogeneity in assessment methods limits definitive conclusions, whereas functional outcomes appeared comparable between the two techniques. Given the presence of nonsignificant findings, wide CIs, and methodological limitations among the included studies, these results should be interpreted with caution, and further well-designed multicenter RCTs are needed to confirm these findings.

Data availability statement

The datasets generated during and/or analyzed during the current study are publicly available.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.