Introduction

Transsexualism [1], which overlaps with gender identity disorder (GID) [2], describes a condition when an individual has a strong desire to adjust their physical appearance to match their gender identification. The overall pooled prevalence of transsexualism of males, called male-to-female (MTF), was approximately 6.8 per 100,000 [3]. Moreover, recent studies have reported a trend of increasing prevalence of MTF to date [4,5,6,7,8,9]. Most MTF pursue treatments that aim to align their appearance to their desired gender and to improve their quality of life (QoL) [10]. To achieve the goals, MTF utilized a variety of therapeutic options including hormonal therapy [11,12,13] and surgical procedures such as breast augmentation, facial feminizing surgery, and gender reassignment surgery (GRS) [14].

The ultimate goal of GRS including penile skin inversion vaginoplasty (PIV) and sigmoid colon vaginoplasty (SCV) in MTF is to establish a female-like perineogenital complex in the aspects of function and appearance [15]. However, in assessing surgical outcomes, the success of the surgical techniques needed to be achieved along with patients’ well-being [16]. Various studies on GRS reported different outcomes in the aspect of QoL [17,18,19,20,21]. According to a survey on 47 Brazilian MTF who underwent PIV using the WHOQOL-100 questionnaire, there was a significant improvement in domains of psychological and social relationships but no significant change in domains of physical health and level of independence [17]. While a study on 31 MTF who underwent bowel vaginoplasty (BV) found that the total mean score using the Satisfaction with Life Scale (SWLS) was 27.7 ± 5.8, indicating high satisfaction [18].

PIV and SCV focused on fulfilling patients’ expectations in terms of function, aesthetic, and QoL. Since MTF are deemed to be in normal physical condition, the primary clinical purpose of the surgical procedures should be to improve QoL. Although several studies demonstrated the difference between PIV and BV in multiple aspects [22,23,24,25,26], there was no research comparing the QoL between techniques. Thus, this study focuses to compare the difference in QoL of MTF who underwent PIV and SCV.

Methods

Study design and sampling

This study was an open-label analytical cross-sectional study on patients who were diagnosed with gender identity disorder (GID) and underwent male-to-female (MTF) gender reassignment surgery (GRS) by penile skin inversion vaginoplasty (PIV) and sigmoid colon vaginoplasty (SCV) at King Chulalongkorn Memorial Hospital (KCMH), a tertiary referral university hospital in Thailand, from January 2002 to December 2022. Participants’ information was collected from the database of KCMH using ICD-10, which they were then recruited during the outpatient follow-up visits at the department. No sampling strategy was used in the study as we attempted to recruit all the eligible individuals.

The inclusion criteria were patients who (1) underwent PIV or SCV performed by the plastic and reconstructive surgery team of KCMH, (2) agreed to sign their informed consent, and (3) underwent the mentioned GRS surgeries for more than 3 months. The exclusion criteria are patients who (1) underwent PIV before SCV, (2) could not be contacted by their provided information, and (3) denied participating.

Procedure protocol

For GRS in KCMH, two main surgical operations were PIV and SCV. Three main surgeons performed both procedures and used the same approach. In brief, PIV technique uses penile skin and scrotal-perineal flap as a neovaginal lining. During SCV, the sigmoid colon was harvested laparoscopically by a general surgeon, and then the plastic surgery team dissected the perineum. Following that, the sigmoid colon was transplanted and sutured to the neovagina [27, 28].

Data collection

Patients were asked to complete the demographic data form and Short-Form 36-Question Health Survey version 2 (SF-36v2) by the researchers without a time limit and influence on the answers. The study flow diagram is shown in Fig. 1. The information was reported following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines [29]. The reported checklist was provided in supplementary material 1.

Fig. 1
figure 1

Study flow diagram. Abbreviations: GRS, gender reassignment surgery; PIV, penile skin inversion vaginoplasty; SCV, sigmoid colon vaginoplasty

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The primary outcome of the study was health-related QoL using the SF-36v2. SF-36 questionnaire is a self- administered questionnaire consisting of 36 questions assessing QoL across eight domains including Physical Functioning, Physical Role, Bodily Pain, General Health, Vitality, Social Functioning, Emotional Role, and Mental Health [30]. These eight domains were categorized into the Physical Component Summary (PCS) and Mental Component Summary (MCS). The Physical Functioning, Physical Role, and Bodily Pain domains correlate highly with the PCS. The Emotional Role and Mental Health domains correlate highly with the MCS. Three of the domains (General Health, Vitality, and Social Functioning) correlate with both major component summaries. The Thai version of SF-36v2, which was calibrated by Lenette et al. to have no difference from the English version, was used in this study [31]. The response was calculated using norm-based scoring by using linear T-score transformations to make scores for component summary measures. Health domain scales have the same mean average of 50 and standard deviation of 10. A higher score in each domain indicates superior health [32].

Statistical analysis

The normal distribution of continuous variables was tested using visualization by histogram and the Shapiro–Wilk test. All continuous variables were represented as median (interquartile range) due to not normally distributed data. No descriptive variable was used in the study. The Mann–Whitney U-test was performed to compare the QoL between the PIV group and the SCV group. The probability of finding a statistically significant difference (power) in the non-significant QoL domains was estimated using alpha = 0.05 and the results from the study [33]. A p-value < 0.05 was considered statistically significant. Missing data and incomplete data were excluded from the statistical analysis. Stata version 17.0 (StataCorp, College Station, TX 77845 USA) was used for all data analysis.

Results

Baseline characteristics

From 2002 to 2022, a total of 278 eligible cases of MTF GRS were identified using ICD-10. Fifty-seven patients completed the questionnaires. Of these, 37 (64.9%) patients underwent PIV, and 20 (35.1%) patients received SCV. The median (IQR) age of the patients in the PIV and SCV groups was 30.0 (28.0–36.0) and 28.0 (24.0–37.0) years, respectively. The median (IQR) BMI of the patients in the PIV and SCV groups was 20.3 (18.6–21.4) and 19.9 (17.5–21.0) kg/m2, respectively. The median (IQR) age of self-recognition for patients in the PIV and SCV groups was 9.0 (5.0–16.0) and 9.0 (6.0–15.0) years, respectively. Other demographic characteristics including age of beginning living as a female, duration of living as a female before surgery, age of first hormone exposure, age of surgery, and postoperative satisfaction are demonstrated in Table 1. Between the two groups, demographic data revealed no statistically significant difference.

Table 1 Demographic characteristics of included participants
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Quality of life (QoL)

The PIV group demonstrated a median (IQR) QoL score of PCS of 51.9 (44.3–55.7), and the SCV group was at 54.0 (48.2–57.1). The median (IQR) of MCS scores in the PIV and SCV groups was 44.3 (37.0–52.3) and 51.2 (47.8–53.5), respectively. In terms of summary QoL, MCS demonstrated a statistically significant difference between the two groups (p = 0.02). In the subdomains, the SCV group showed significant differences in QoL than the PIV group in the seven out of eight domains except in the General Health domain (p = 0.08). Moreover, across all eight domains of QoL, the median values for each domain in the SCV group were higher than those in the PIV group. All results of the QoL in the study are shown in Table 2. The power estimations for PCS and the General Health domain were 0.22 and 0.51, respectively.

Table 2 SF-36 Component’s summary and domain scaled score
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Discussion

This research was the first analytical cross-sectional study comparing the long-term postoperative quality of life (QoL) between penile skin inversion vaginoplasty (PIV) and sigmoid colon vaginoplasty (SCV). Statistically significant difference was found only in the Mental Component Summary (MCS) between the two groups. The lack of a significant difference in QoL between the two groups in the Physical Component Summary (PCS) could possibly be attributed to the similar treatment effects of both surgical techniques. However, it is more likely that the inadequate sample size for the study contributed to this outcome. Nevertheless, it is important to note that the values of PCS in both groups were close.

The use of well-constructed, reliable, and authorized questionnaires is important to help obtain data about the satisfaction and effectiveness of the surgery [34]. Globally used and validated instruments for evaluating health-related quality of life are SF-36 and WHOQOL-100 [35]. SF-36 questionnaire is a self-administered questionnaire consisting of only 36 questions [30], while WHOQOL-100 contains 100 questions [1]. Both questionnaires can be used to evaluate QoL, but SF-36 was used in this study, as the eight domains cover most measured health concepts and easy to collect information with high-quality data [30].

Most of the domains showed a statistically significant difference in SCV compared with PIV. The significantly higher score in seven out of eight domains in the SCV group may result from the SCV technique using the bowel as the vaginal canal lining which resembles the physiological female vagina in texture, appearance, and self-lubricating ability [36]. Therefore, it requires less postoperative self-neovaginal dilatation. A systematic review of surgical techniques demonstrated there were fewer neovaginal complications including neovaginal stricture and less wound dehiscence in the bowel vaginoplasty (BV) group compared with the PIV [22]. No statistically difference was found in General Health domain, reflecting respondents’ health status rating which might be due to the necessity of additional surgery to access the abdominal cavity for bowel segment harvesting, which could results in long-term intraabdominal complications such as constipation [23]. With a study power of 0.51 in the study, we cannot reject the possibility of an inadequate sample size to achieve a statistically significant difference.

From our study, the SCV group had higher median values in all the domains compared with the PIV group, implying SCV patients may have achieved better postoperative QoL. Following the surgery, functional and physical outcomes were strongly associated with patient satisfaction [37]. SCV is a reliable technique for achieving satisfactory vaginal depth that is both sexually functional and pleasing to the patient [38]. Additionally, MTF who received BV had high satisfaction with functional urogenital system and aesthetic aspects [18]. A meta-analysis on MTF also revealed that patients who underwent BV were more likely to achieve orgasm compared with PIV reflecting the ability to preserve genital sensation in BV [23]. Furthermore, high patients’ satisfactions were also associated with sexuality [39]. More than half of the PIV patients mentioned they were sexually inactive due to inadequate lubrication and discomfort during intercourse [40]. The naturally self-lubricating neovagina from SCV might improve sexual satisfaction and QoL.

There are no optimal techniques for GRS due to the unavailability of large comparative studies between available techniques. Nevertheless, the first line and most frequent technique used for vaginoplasty is PIV as it could fulfill patient satisfaction and is less invasive with no abdominal complications, and good functional and aesthetic outcomes [23, 24, 41]. On the contrary, PIV tended to result in stenosis, which is secondary to the wound healing process and skin graft contraction requiring adequate postoperative dilatation [42]. Additionally, the canal may get dry from the absence of natural lubrication [42]. These results could support our findings that the SCV group had better overall QoL than the PIV group. However, based on our center, SCV costs more than PIV according to the necessity of entering the abdominal cavity to harvest bowel segments. On the other hand, Brazilian trans women underwent GRS using the gold standard technique (PIV). QOL after GRS study in Brazilian society, most of the population were satisfied with GRS [43].

Other surgical options to increase QoL in MTF include facial feminization surgery (FFS) and breast augmentation surgery (BAS) [44]. Ainsworth et al. conducted a survey on MTF who underwent GRS and FFS and found that there was a significant improvement in QoL by SF-36v2 in physical, mental, and social aspects [45]. Moreover, a prospective cohort study revealed that FFS improved QoL with satisfying aesthetic outcomes and minimal complications [46]. Using the BREAST-Q questionnaire, Weigert et al. found an improvement in breast satisfaction, psychological well-being, and sexual well-being following BAS [47]. The most effective procedure to improve QoL is inconclusive because of no prior studies comparing QoL after GRS, FFS, and BAS. More studies are needed to provide sufficient evidence in terms of cost-effectiveness and QoL improvement between GRS, FFS, and BAS.

Limitations and suggestions

The limitations of this study include a small sample size that results in less generalizability and feasibility of conducting subgroup analysis of QoL by possible factors that may cause the differences between the two groups. Another limitation was that within-group comparison of QoL during pre- and postoperative was not conducted, which might lead to unidentified differences between pre- and postoperative periods. In addition, our study may contain certain biases due to the nature of the study design. Furthermore, the omission of patient selection details could affect the generalizability of the findings, and the study does not thoroughly investigate postoperative complications, crucial for assessing procedure safety and risk. Further studies on QoL, complications, and cost-effectiveness are suggested to recommend the type of GRS procedure for MTF and GRS in different individuals. In a longitudinal study, the researcher should assess the ability to orgasm, vaginal depth, lubrication, hair removal, postoperative dilation, sexual function, and complications, as this may impact patient perceptions of quality of life.

Conclusions

While requiring more operative steps and resources, male-to-female individuals who undergo sigmoid colon vaginoplasty may achieve a higher quality of life compared to those who undergo penile inversion vaginoplasty. Further studies on the efficacy and other aspects of sigmoid colon vaginoplasty and penile inversion vaginoplasty are needed to compare the two surgical techniques.