While the contribution of smooth and striated muscle to female urinary continence has been well described, the role of adjacent neurovascular structures remains poorly understood. The female urethra is surrounded by the corpus spongiosum, which splits distally and terminates in the glans clitoris (1). Prior anatomic investigations utilizing selective urethral artery occlusion have revealed that the vascular tone of corpus spongiosum and adjacent structures contributes up to one third of the intraurethral pressure in females at rest (2). Further, dense sensory innervation of the periurethral vascular tissue noted on anatomical studies of rat support the putative role of vascular cavernosae as a hub for integrating neural signals with blood flow during micturition and sexual function. Studies utilizing power doppler have linked the decrease in periurethral blood flow to worsening continence parameters. Because MRI offers excellent spatiotemporal resolution (3) for imaging vasculature, we hypothesized that pelvic MRI as an optimal modality to evaluate periurethral vascular cavernosae and their contribution to urinary continence.

We retrospectively analyzed the scans of eight 26-72 years old women with pelvic pain who initially underwent MRI based urography for either a research study on bladder permeability or underwent diagnostic MRI for standard of care at Prisma 3T scanner with 4-channel flexible receiver coil centered on the pelvis. Protocol involved free breathing, multi- slice T2 weighted scans lasting 60s with 16 x 16 cm field of view with a slice thickness of 3 mm or T1 weighted scans with or without intravenous injection of gadolinium-based contrast agent. After deidentification, vascular cavernosae on urethral meatus was localized by a single board-certified radiologist.

We retrospectively reviewed the scans of two nulliparous and five multiparous women in the age-range of 26-72 years together with diagnostic MRI of single woman with unknown parity status.  T2 weighted spin echo scans segmented female urethra as a middle layer of hyperintensity sandwiched between outer and inner layers of hypo intensity. A protuberance containing <6mm wide vascular cavernosae was seen anterior of urethral meatus, below the pubis symphysis bone of all women, which is enclosed by red outline in Figure 1 and 2. Injection of gadolinium-based contrast agent for diagnostic MRI (Figure 2) produced concomitant contrast enhancement of vascular cavernosae and of adjacent clitoral bulbs. The enhanced anatomical region on urethral meatus corresponds to the expected anatomic position of the corpus spongiosum.

This retrospective review of MRI scans affirmed the existence of engorged vascular cavernosae on urethra meatus at resting state of female urethra. The concomitant enhancement of vascular cavernosae and clitoral bulbs is consistent with the purported role of Kobelt plexus during arousal, on ultrasound study.  We suppose that the vascular cavernosae noted on cadavers (1) fits the description of Kobelt plexus, with vascular capacity to hold excess blood supply of urethra beyond the presumed metabolic demands of urethra (2). We reason that gadolinium injection timed to the voluntary event of voiding in MRI scanner by both continent and incontinent women can answer whether vascular cavernosae engorged with blood adds vascular resistance to the resting tone of closed urethra and whether that resistance declines during voiding. In addition, dynamic MRI can establish whether reduced blood supply to vascular cavernosae determines 3-5-fold increased risk of urethral atrophy and incontinence in patients suffering from hypertension and vascular diseases.

This hypothesis-generating retrospective analysis of MRI scans substantiates prior anatomic and ultrasonographic studies on engorged vascular cavernosa in both multiparous and nulliparous women at resting state of urethra. These findings validate the use of MRI for future studies exploring the relationship of blood flow to vascular cavernosa (corpus spongiosum) and the maintenance of urinary continence.

Hoag N, Keast JR, O'Connell HE. The "G-Spot" Is Not a Structure Evident on Macroscopic Anatomic Dissection of the Vaginal Wall. J Sex Med. 2017 Dec;14(12):1524-1532.
Rud T, Andersson KE, Asmussen M, Hunting A, Ulmsten U.  Factors maintaining the intraurethral pressure in women. Invest Urol. 1980 Jan;17(4):343-7.
Saidman JM, Aineseder M, Garratt J, Wang MX, Ahmed I, Elsayes KM, Gomez M, Rendón Yugcha FO, Chacón CRB, Ocantos JAaging the Female Urethra: US and MRI in Cystic and Solid Pathologic Conditions. Radiographics. 2025 Mar;45(3):e240064.