What imaging studies measure vestibular bulb size and correlate anatomy with sexual response?

1. What has been measured: MRI studies that quantify bulb dimensions

Unenhanced and contrast‑weighted pelvic MRI protocols have been used to visualize the clitoris, crura and vestibular bulbs and to measure cross‑sectional widths and volumes in living women, with published comparisons showing smaller vestibular bulb widths in postmenopausal versus premenopausal subjects ^[1] and multiple MRI papers referenced in recent reviews and consensus efforts documenting measurable vestibular anatomy in vivo ^{[4] [5]}.

2. Ultrasonography and functional correlations: a tentative bridge to orgasmic reports

Transperineal or anterior vaginal‑wall ultrasonography has been proposed as a simple clinical tool to map anterior vaginal space and related clitoral‑urethrovaginal anatomy, and at least one line of work reported that sonographic measures of the anterior vaginal wall (interpreted as reflecting the clitoral‑urethrovaginal complex) can be correlated with capacity for vaginally‑activated orgasm—though that literature treats the vestibular bulbs as one element of a broader complex rather than isolating bulb size alone ^[2].

3. High‑resolution anatomy: microCT, cadaver dissection and histology define structure but not function

Cadaveric dissection, histology and microCT have clarified relationships of the vestibular bulbs to the clitoris and urethra and have allowed volume rendering of erectile structures, but these ex vivo techniques principally refine anatomy and innervation maps rather than producing living‑subject functional correlations; microCT work has shown distinct erectile tissues and enabled segmentation of bulbs but did not by itself link size to sexual response measures ^{[6] [3] [7]}.

4. What the functional literature actually shows about size and sexual response

Reviews and physiological syntheses assert that the vestibular bulbs engorge during arousal and contribute mechanically and reflexively to orgasmic contractions via bulbocavernosus activity (a mechanistic role described in reviews) but also acknowledge that the subjective experience of orgasm depends on many psychosocial and neural factors, and empirical studies directly correlating simple biometric bulb size with desire, arousal or orgasm are sparse and sometimes negative—examples include clinical reports finding no significant difference in desire/arousal/orgasm outcomes in certain comparative groups despite anatomic differences ^{[8] [9] [10]}.

5. Why evidence is limited and where bias or agendas can shape interpretation

Methodologic limits—small sample sizes, variable imaging protocols, inconsistent terminology for bulb anatomy and differences between in vivo imaging and cadaveric metrics—constrain conclusions and help explain why recent efforts emphasize standardized terminology and imaging approaches to allow future quantitative work ^{[5] [11]}; additionally, clinical and surgical agendas (protecting sexual function after periclitoral surgery) have driven anatomical imaging studies, which can skew research toward surgical preservation questions rather than pure psychosexual correlation ^{[6] [7]}.

6. Bottom line and research gaps to resolve

Imaging modalities that measure vestibular bulb size include MRI and ultrasound for living subjects and microCT/cadaveric imaging for structural detail, and there is mechanistic evidence that bulbs engorge during arousal, but robust, reproducible correlations between measured bulb size and validated sexual‑response outcomes are not yet established in the literature; standardized imaging protocols, larger cohorts linking objective measures to validated sexual function instruments, and multimodal functional imaging remain the path forward ^{[1] [2] [3]}.