“Outcomes Following Metoidioplasty and Phalloplasty Gender Affirming Surgery (MaPGAS) with Urethral Lengthening: A Modified Delphi Consensus Study”

Abstract

Objective

To generate surgeon consensus on metoidioplasty and phalloplasty gender-affirming surgery (MaPGAS) outcomes statements using a modified Delphi method.

Materials and Methods

We invited MaPGAS surgeons to anonymously participate in a two-round web-based Delphi survey to generate consensus on patient centered outcome statements generated from surgeon practice patterns, literature review, and patient input. Consensus was predefined as at least 70% agreement. Surgeons were asked to provide open ended feedback on statements which were thematically analyzed and used to revise statements not reaching consensus for a second-round survey.

Results

Twenty-one metoidioplasty and phalloplasty surgeons were invited and 16 (76%) reviewed 39 statements in round one and 17/20 (85%) reviewed 10 statements in round two. Following round two, nearly all statements reached consensus: 14/15 (93%) of statements on metoidioplasty, 11/12 (92%) of radial forearm phalloplasty statements and 12/12 (100%) of anterolateral thigh phalloplasty statements. We found that 12/12 (100%) statements on sexual health, 8/8 (100%) statements on non-urinary complications, and 16/18 (89%) statements on urinary outcomes met consensus.

Conclusions

In a modified web-based Delphi survey, surgeons reached consensus on nearly all outcome statements. Variations in surgeon experience, length of follow up, and reporting of outcomes contribute to different definitions of urinary complications. Results from this study will help create decision making tools for individuals considering metoidioplasty and phalloplasty

Introduction

Metoidioplasty and phalloplasty gender affirming surgery (MaPGAS) may be sought by transgender male and nonbinary individuals assigned female at birth to alleviate gender incongruence. A variety of surgical options are offered based on patient goals, anatomy, and risk tolerance. Patients primarily have a choice between phalloplasty or metoidioplasty. Phalloplasty requires tubularization of local or free flaps to create a penis; metoidioplasty utilizes the clitoris and local genital tissue to create a penis.^1,2 Additional procedures include scrotoplasty, urethral lengthening (UL) to allow urination from the end of the penis, colpectomy/vaginectomy, and subsequent implantation of testicular and/or erectile prostheses.

The current literature lacks consensus on outcomes for MaPGAS, yielding complication profiles that are inconsistent and difficult to interpret. Reporting of urinary outcomes should be a standard practice. However, highly variable technique and individual surgeon definitions of complications reflect the surgical community’s lack of consensus. Urethral complication rates in MaPGAS with UL are estimated to be greater than 25%.³ These outcomes are frequently drawn from systematic reviews generated from low-quality literature with resultant variable findings.⁴ Data from surgical quality databases is not necessarily a source of greater certainty as bioinformatic barriers make identifying these procedures difficult,^5,6 and definitions of success or complications cannot be relied upon. In addition, the paucity of robustly validated patient-reported measures for this population hinders surgeon ability to counsel patients on outcomes relating to sexual health, resolution of gender incongruence, and other subjective experiences expected to improve with surgery.^7–9

Given these limitations, and the small number of surgeons with expertise in gender affirming surgery,¹⁰ deriving practicing surgeon consensus through a Delphi process of determining agreement with statements through multiple rounds,^11–14 may better describe MaPGAS outcomes. Delphi studies can be utilized to define core outcomes,¹¹ set practice guidelines,¹² and estimate incidence.¹³ Delphi methodology has demonstrated efficacy in making quantitative judgements to address a knowledge gap, in this case, unknown rates of outcomes informing patient decision-making.¹⁵The purpose of this study is to utilize a modified electronic Delphi method to derive surgeon consensus on patient centered MaPGAS outcomes. Resultant findings will be used to develop MaPGAS decision making tools for patients and surgeons.

Materials and Methods

Following BLINDED Institutional Review Board review (STUDY 02000222), we conducted a modified web-based Delphi study. This approach relies on a panel of experts who provided informed consent to review and anonymously address outcomes statements from an electronic survey with 2 or more rounds of iteration.¹⁶ Invited participants were from a mix of 12 academic and private practice settings, performed over 10 index or revision MaPGAS cases per year, and had authored relevant MaPGAS outcome related publications. A variety of techniques were represented within respondent’s practice, such as multiple or single stage urethral lengthening in phalloplasty, and use of differing local tissue grafts during metoidioplasty with urethral lengthening. With each subsequent survey round, a summary of the previous round was provided. This process is continued until consensus is reached or the opinion stabilizes.

A pre-Delphi preparation phase was carried out which involved a systematic literature review,³ a practice pattern query of invited experts,¹⁷ and a qualitative study of MaPGAS outcomes impacting patient decision making.¹⁸ Findings from the 3 studies in the preparation phase were reviewed by MaPGAS patients and clinicians to construct the definitions and rates of outcomes included in the initial Delphi statements, such as that rates of flap necrosis not requiring surgical correction after RF phalloplasty were <10% given the systematic review finding of an 8% rate of this complication.^3,19 The importance of patient input in this phase is demonstrated by the nuanced expansion of the standing to urinate definition after metoidioplasty–a key aspect of MaPGAS patient decision making.¹⁸ Following survey revisions, standing to urinate included description and illustration of urinating with the penis through the pant fly (Supplementary Figure 1) or modified standing to urinate with the pants fully lowered (Supplementary Figure 2).

Round 1 of the Delphi surveys was administered in May 2022. Participants were asked to review a selection of 39 outcome statements pertaining to MaPGAS procedures which they performed, and to designate agreement or disagreement. Statement consensus was defined as ≥70% agreement.¹⁴ Free text comments were solicited in each round to describe how outcomes were assessed, to explore patient factors associated with complications, and to explain statement disagreement. Following review and discussion at the American Urologic Association meeting in May 2023²⁰ and the Society of Genitourinary Reconstructive Surgeons Academic Congress in September 2023, a second round Delphi survey was created. This new survey consisted of revised first round statements that did not meet consensus and was distributed in March 2024.

An analysis of the qualitative comments was carried out and reviewed by 3 authors (BLINDED, BLINDED, BLINDED), which included representation of MaPGAS surgeons and community members with experience undergoing MaPGAS.¹⁹ Statements were evaluated and grouped into 3 categories: rates of achieving desired goals relating to sexual health and size, goals and complications related to urination outcomes after urethral lengthening, and non-urinary outcomes. The rates of outcomes and complications found in the initial systematic review were then contrasted with expert consensus on rates in the final round. Open-ended comments written by respondents who disagreed with the proposed statements were categorized into 3 groups: 1) Definitions of Outcomes and Methods of Assessment, 2) Radial Forearm flap (RF)/Anterolateral Thigh Flap (ALT) Similarities, and 3) Complication Risk Factors and Treatment.

Results

In round 1, 16 surgeons participated. In round 2, 17 surgeons completed the survey. Of the round 1 respondents, 13 surgeons (81%) performed metoidioplasty, 13 surgeons (81%) performed RF, 10 surgeons (63%) performed ALT phalloplasty, and 11 (69%) performed both metoidioplasty and a phalloplasty procedure.

Survey revisions were made based on round 1 surgeon input. Round 2 statements reached consensus in 14/15 (93%) metoidioplasty (Table 1), 11/12 (92%) RF phalloplasty (Table 2), and 12/12 (100%) of ALT phalloplasty statements (Table 3). All statements met consensus in the sexual health and size outcomes category (12/12, 100%) and in the non-urinary outcomes category (8/8, 100%). Only 2 statements (16/18, 89%) did not meet consensus in the urinary outcomes category during Round 2: urethral stricture risk following metoidioplasty ≤ 10% [9/14 (64%)]; and RF fistula risk up to 50% [10/15 (67%)]. Qualitative feedback from Round 1 emphasized differences in surgical experience and techniques, and guided deviation from statistics initially sourced from systematic review:

Table 1.

Metoidioplasty Statements

Statement (Category)	N Agreement / N Evaluating Outcome (%)
Statements Meeting Consensus
The likelihood of any wound complication requiring surgical intervention not involving the urethra (hematoma, infection, etc.) following surgery with urethral lengthening is <5%. (NUO)	11/12 (92%)
The likelihood of any wound complication not involving the urethra (hematoma, infection, etc.) following surgery is up to 30%. (NUO)	10/12 (83%)
The likelihood that the patient will have tactile sensation of the penile shaft is >90%. (SHS)	12/12 (100%)
The likelihood of erogenous sensation on the penile shaft is >90%. (SHS)	12/12 (100%)
The likelihood that the patient will have an erection suitable for penetration of a partner without external device assistance after surgery is <5%. (SHS)	10/10 (100%)
The average penile length following surgery NOT on stretch is ~2–4cm. (SHS)	12/13 (92%)
The likelihood that the patient will have an unassisted erection after surgery is >90%. (SHS)	10/11 (91%)
The average penile length measured on stretch following surgery is ~5cm. (SHS)	9/11 (82%)
The likelihood of urethral fistula following surgery is up to 20%. (UO)	12/12 (100%)
The likelihood of standing to urinate with pants lowered below waist in patients with ~2cm pre surgical length and prominent mons is 70%. (UO)	10/12 (83%)
The likelihood of stand to urinate through fly in patients with a 2–4cm pre surgical length is <20%. (UO)	9/11 (82%)
The likelihood that the patient can urinate through the distal tip of the penis is >90%. (UO)	9/12 (75%)
Of patients developing urethral fistula, 30% will require surgical intervention. (UO)	8/12 (75%)
Statements Not Meeting Consensus
The risk of urethral stricture following metoidioplasty with urethral lengthening is ≤10%. (UO)	9/14 (64%)
Open-text responses from respondents explaining disagreement:
– I believe the rate is higher - 15–20% – I think it is closer to 10–25% – I think the rates in our hands are higher than 10% – This low number is likely skewed by attrition bias or short term follow up. It is probably 10–15% in experienced hands.

Table 2.

Radial Forearm Phalloplasty Statements

Statement (Category)	N Agreement / N Evaluating Outcome (%)
Statements Meeting Consensus
The likelihood of any donor site wound complication requiring surgical intervention (hematoma, infection, etc.) after surgery is <10%. (NUO)	8/10 (80%)
The likelihood of flap necrosis requiring surgical intervention following surgery is 5%–10%. (NUO)	7/10 (70%)
The likelihood of erogenous sensation at the site of clitoris (buried or unburied) is >90%. (SHS)	11/11 (100%)
The average penile length is 12cm. (SHS)	12 /13(92%)
The likelihood that the patient will have tactile sensation of the penile shaft is 80%. (SHS)	8 /10 (80%)
The likelihood of stand to pee through fly after surgery is >90%. (UO)	11/13 (85%)
Of patients developing urethral fistula, surgical intervention will be required in >30%. (UO)	10/12 (83%)
The likelihood that the patient can pee through the distal tip of the penis is >90%. (UO)	9/12 (75%)
The risk of any flap necrosis following RF phalloplasty is up to 10%. (NUO)	13/15 (87%)
The risk of urethral stricture following RF phalloplasty with urethral lengthening is up to 50%. (UO)	11/15 (73%)
Of patients developing urethral stricture, almost all (≥90%) will require surgical intervention. (UO)	15/15 (100%)
Statements Not Meeting Consensus
The risk of urethral fistula following RF phalloplasty with urethral lengthening is up to 50%. (UO)	10/15 (67%)
Open-text responses from respondents explaining disagreement:
– because its much lower. 10–20% – Higher, up to 60% – I believe the fistula rate is lower (up to 25%) – Same comment as above (“It should not be [up to 50%]. At our center our rate of stricture is around 8–10%. [Alternate centers are] I believe around 16%. Fistulas are higher than strictures but more around 20%. – Saying ‘up to’ is too optimistic; AT LEAST would be better.

SHS=sexual health and size, UO=urinary outcome, NUO=non-urinary outcome, RF=radial forearm, UL=urethral lengthening.

Table 3.

Anterolateral Thigh Phalloplasty Statements

Statement (Category)	N Agreement / N Evaluating Outcome (%)
Statements Meeting Consensus
The likelihood of any donor site wound complication requiring surgical intervention (hematoma, infection, etc.) after surgery is <5%. (NUO)	8/10 (80%)
The average penile length is >12cm. (SHS)	8/10 (80%)
The likelihood that the patient will have tactile sensation of the penile shaft is <60–70%. (SHS)	7 /10(70%)
The likelihood of stand to pee through fly after surgery is >70%. (UO)	7/10 (70%)
Of patients developing urethral fistula, surgical intervention will be required in >30%. (UO)	7/10 (70%)
The likelihood of urethral stricture is ~50%. (UO)	9/10 (90%)
Of patients developing urethral stricture, surgical intervention will be required in >50%. (UO)	8/10 (80%)
The likelihood of urethral fistula following surgery is 35%. (UO)	7/10 (70%)
The risk of flap necrosis that requires surgical intervention following ALT phalloplasty is up to 10%. (NUO)	9/11 (82%)
The risk of any flap necrosis following ALT phalloplasty with urethral lengthening is up to 20%. (NUO)	9/11 (82%)
The probability that the patient will have erogenous sensation at the site of natal clitoris (buried or unburied) after ALT phalloplasty is >80%. (SHS)	10/11 (91%)
The probability that the patient can pee through the tip of the phallus following ALT phalloplasty with urethral lengthening is up to 75%. (UO)	8/11 (73%)

SHS=sexual health and size, UO=urinary outcome, NUO=non-urinary outcome, ALT=anterolateral thigh.

Outcomes and Methods of Assessment

Clinician-observed outcomes such as stricture (Figure 1a) and fistula (Figure 1b) often received qualifying comments. For example, factors such as timing (early versus late) significantly changed fistula management:

“Sorry WHEN do they have fistula? Early fistulas may heal and maybe 50% do heal.”

“Depends on how we define fistula. If a fistula is closed at 6 weeks, it’s probably just normal postop healing.”

Questions of which events should be counted towards an outcome arose when discussing necrosis, flap loss, and wound healing complications:

“I would argue partial flap loss requiring debridement/skin graft should be the only ones counted. A 3 mm rim that scabs off should not be considered partial flap loss”

In surgeons that evaluated subjective outcomes, a variety of methods were used. For example, when obtaining measurements of tactile sensation in RF phallus, 5 surgeons used a subjective patient report, acknowledging subjective reports did not utilize a validated measure. Other specified physical exam findings were used, such as “closed eye pin prick.” One respondent specified using both physical exam and patient history.

Outcomes of RF Phalloplasty Compared to ALT Phalloplasty

For statements on urinary outcomes and sensation for ALT and RF phalloplasty patients, respondents indicated that rates quoted were more similar than the differentials proposed. Most respondents thought the 25% rate of occurrence of urethral strictures in RF phalloplasty statement in round 1 was low. Responses from those that disagreed (4/12) quoted a range of stricture rates from 30–50%. For ALT phalloplasty, the proposed rate of strictures of about 50% was accepted by all but 1 respondent. Careful ALT patient selection may improve urethral complication rates to RF phalloplasty levels:

“In select patients with thin thighs and pliable thigh adipose tissue and skin, the ability to stand to urinate is equal to the RF patient population.”

Regarding sensation after ALT phalloplasty in round 1, all surgeons disagreed with the quoted rates of retained clitoral and tactile sensation.

“Clitoral nerve is treated no different than [in RF phalloplasty] so it should be the same.”

Proposed tactile sensation conferred by microsurgical nerve coaptation was also thought to be conservative, though both RF and ALT statements achieved consensus. Those who disagreed with quoted rates advocated for equivalency between donor sites.

“We see nearly identical tactile sensation with ALT and RF.”

Complication Risk Factors and Treatment

Infection, poor wound healing, and lack of vaginectomy were cited as factors that predisposed patients to fistula. In the setting of metoidioplasty, stricture was thought to be associated with surgical technique (n=5), small labia minora (n=3) and lichen sclerosus (n=3). Some respondents indicated that strictures, when they occur, almost always require surgical correction. Others felt that metoidioplasty and RF phalloplasty patients developing urethral strictures required surgical intervention about 50% of the time. A majority (n=7 metoidioplasty, n=6 RF phalloplasty, n=2 ALT phalloplasty) asserted that a clinically significant stricture would warrant surgical treatment:

“Depends how you define stricture, but I treat everyone with a stricture surgically (rarely dilation, typically urethroplasty).”

Length of follow up also modified urinary outcomes, with changes in both incidence of strictures and patient voiding behavior:

“I believe the 2cm length and prominent mons will have a higher negative effect on modified STP [standing to pee] than 70%. It would still be lower. I also think that patients may initially try to stand to pee, but over time will revert to sitting.”

Discussion

This is the first modified web-based Delphi survey on MaPGAS outcomes. Respondents reported agreement on the majority of MaPGAS statements covering community derived sexual and urinary outcomes of interest. These results differed from prior systematic review of the literature (Table 4).³ There was specific disagreement amongst surgeons on urethral stricture rates following metoidioplasty and urethral fistula rates following RF phalloplasty. Respondents also reported that almost all strictures required surgical correction, regardless of procedure. Interestingly, surgeons stated that the results of RF and ALT were more similar than initially proposed, particularly with careful patient selection. These results demonstrate the evolving nature of MaPGAS urinary outcomes when compared to what has been described.

Table 4.

Comparison To Systematic Review of the Literature

Outcome	Systematic Review Rate	Delphi Consensus Rate
Urethral Stricture
Metoidioplasty	25%	No Consensus
RF	32%	≤50%
ALT	28%	~50%
Urethral Fistula
Metoidioplasty	21%	≤20%
RF	36%	No Consensus
ALT	22%	35%
Standing Urination
Metoidioplasty	74%	<20%a
RF	99%b	>90%
ALT	78%	75%
Wound Complications
Metoidioplasty	63%	≤30%
RF	8%	≤10%c
ALT	17%b	20%c

^aDefined as urination through a pants fly in patients with a 2–4cm pre surgical length

^bReported in only one included study

^cDefined as flap necrosis not requiring surgical correction

RF=Radial Forearm, ALT=anterolateral thigh

Urethral strictures and fistulas are common MaPGAS complications.²¹ Though limited, prior literature suggests they occur in 0–25% of metoidioplasty and 25–60% or more of phalloplasty cases,³ making it difficult to accurately counsel patients. Amongst our surgeon panel, metoidioplasty urethral stricture rates nearly reached consensus, with disagreeing respondents citing that <10% was too low and the more likely stricture rate was between 10–25%. Conversely, the RF fistula rate up to 50% was generally seen as too high. The lack of consensus was likely multifactorial and related in part to surgeon experience, variation in technique, follow up practice patterns, and heterogeneous stricture definitions. To build on MaPGAS outcome understanding, there is not only a need for more precise stricture definitions, but also for long term patient follow-up as initial strictures may present 6–36 months after surgery.²² Further evidence for having extended follow up includes a reported stricture recurrence rate of 40% at a mean of 15 months after initial surgical repair.²³ Several respondents expressed fistula, stricture, and necrosis definitions as open to subjective interpretation. A simpler metric for assessing urethral success of the index surgery, such as the need for urethral revision, may help with producing more comparable and objective results.

Patients and surgeons also have multiple definitions for other outcomes which are historically reported as singular, binary end-points including standing to void (through fly or with pants lowered), penile length (on stretch or not), and penetrative sexual function (able or not).²⁴ There was more consensus on patient reported outcomes such as tactile sensation or standing urinary function. However, evaluation of these outcomes was not carried out using standardized outcome measures. For example, the “closed-eye prick test” or 1-point awareness provides basic information about tactile sensation, but it misses details that would be obtained by a validated patient reported outcome measure. The primary nerve coaptation is not different in RF and ALT phalloplasty, and patients may have similar 1-point awareness sensation outcomes.²⁶ RF flaps may offer a greater chance of 2 point discrimination due to greater nerve distribution within the RF flap.²⁵ This is similarly seen in breast reconstruction where flap choice yields differing sensory outcomes.²⁸

Variation in recommended follow up protocols and patient factors may further explain the Delphi survey differences. Further, not all patients present for prescribed follow up, and surgeons with a patient population travelling greater distances may have a less accurate understanding of complications for patients who seek local care. Some patients may present with more favorable anatomy which better aligns with their surgical goals; others may not. For example, shorter clitoral length and more mons adiposity prior to metoidioplasty was associated with a lower probability of standing to urinate. Low donor site adiposity with pliable skin for ALT phalloplasty was thought to confer similar outcomes to those observed in RF phalloplasty patients. Also, larger labia minora size and quality were reported as ideal patient factors for the prevention of metoidioplasty urethral stricture and fistula.

While more robust surgical and patient-reported outcomes research is on the horizon, consensus statements allow for surgeon opinion to acutely address limitations and gaps in the primary literature driven by heterogeneous techniques, follow up, and outcomes definitions. The generalized input from this study suggests the need for further work to refine measurable outcomes with validated and standardized methods. Body mass index (BMI kg/m²²) has historically been used as an easily measured surrogate for adiposity and/or a correlate for surgical wound-healing risk.³⁰ BMI is a broad marker and not specific to individualized patient anatomy. More specific markers for MaPGAS may be better for risk and goal probability stratification. In predicting success in standing to urinate following metoidioplasty, for example, skin-to-pubic symphysis distance measurements and visibility of the glans clitoris while in the standing position are likely more accurate in predicting voiding success.

Limitations

This study is limited by current field-wide lack of agreement about outcome definitions. While patient-stakeholder engagement allows for stratification of some outcomes with multiple definitions, such as standing to urinate, further stratification may increase the precision of consensus statements. Additional outcomes for future investigation include sexual function in phalloplasty patients without an erectile device and rates of debulking surgery for ALT. The respondents are based at high-volume centers and do not represent the experiences of all surgeons performing MaPGAS. Consensus was not reached on every statement, likely due to a Delphi survey with so many variables and limited outcomes data. However, the near consensus agreement and similarity in feedback was found to be robust enough to provide early guidance to patients and surgeons.

Conclusions

This is the first Delphi study to explore MaPGAS surgeon consensus. There was consensus on all statements except for metoidioplasty urethral stricture rates and RF phalloplasty fistula rates. Variations in experience, length of follow up, and definitions of outcomes contributed to the lack of consensus. Findings from this study will be used to create MaPGAS decision support tools and may help patients and surgeons with shared decision making.

Supplementary Material

Figure 2

Supplementary Figure 2. Modified standing to urinate with pants lowered (b).

Figure 1

Supplementary Figure 1. Standing to urinate through the fly

Data Statement:

The datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable request.