- Email: [email protected]
Sonography of the Clitoris
413
Sonography of the Clitoris Odile Buisson, MD,* Pierre Foldes, MD,† and Bernard-Jean Paniel, MHD‡ *Centre d’échographie, Saint Germain en Laye, France; †Hôpital de Saint Germain en Laye, Clinique Louis XIV, Saint Germain en Laye, France; ‡Hôpital Intercommunal de Créteil, Service de Gynécologie, Créteil, France DOI: 10.1111/j.1743-6109.2007.00699.x
ABSTRACT
Introduction. The prevalence of invasive procedures in diagnosing female sexual dysfunctions and pathologies is high. There is a need for a less invasive evaluation tool and medical imaging of the clitoris may be a solution. The clitoris has already been studied with nuclear magnetic resonance but there are very few sonographic 2D and 3D studies despite the fact that it is a simple, noninvasive, and inexpensive method. Aim. This study aims at determining the feasibility of using ultrasound (US) techniques to image the clitoris in sufficient detail to permit evaluation of anatomy for possible use in study. Methods. The ultrasounds were performed in five healthy volunteers with the Voluson® GE® Sonography system (GE Healthcare Ultrasound, Zipf, Austria), using one 12-MHz flat probe. Main Outcome Measures. The clitoral body’s diameter, the length of the raphe. Results. The three planes—the cross-section, sagittal section, and coronal section—were revealed making it possible to study the entire organ. Conclusion. The sonography is a simple, inexpensive, noninvasive mean which might help for the evaluation of this organ. Buisson O, Foldes P, and Paniel B-J. Sonography of the clitoris. J Sex Med 2008;5:413–417. Key Words. Clitoris; Clitoral Bodies; Bulbs; Sonography; Ultrasound
Introduction
S
tudies of the clitoris anatomy are still very recent and medical imaging is only beginning. However, it seems that a better knowledge of the clitoral anatomy is a prerequisite for the understanding of pathology of the clitoris. Some nuclear magnetic resonance studies [1–4] have already been published; however, to our knowledge, few ultrasound 2D–3D studies of the clitoris has been published [5–6]. Materials and Methods
The study was conducted on a nonaroused clitoris in five healthy volunteers aged 25 to 45 years. The local ethics committee was not consulted because the volunteers’ motivation was essentially feminist and they felt no need to ask for permission to study their own clitoris. However, the women signed an informed consent form. All of these women have no history of perineal surgery or trauma. Women were not taking birth control pills or receiving © 2007 International Society for Sexual Medicine
hormonal treatments. The female sexual function index scoring [7] revealed no sexual dysfunction and the full scale score range was between 27 and 29. We practiced the sonography between day 2 and day 14 of the menstrual cycle. The ultrasound studies were performed with the Voluson® General Electric® Sonography system (GE Healthcare Ultrasound, Zipf, Austria), a 12-MHz flat probe was used. The volunteers were in a gynecologic position. To insure good skin contact the vulva was covered with a good quantity of sonographic jelly to avoid possible interference from air between the labia. The probe was placed on top of the vulva for the transversal and axial section and on the labia majora for sagittal section. It was not very difficult to slide the probe and to study the entire clitoris in every section: it is far less complicated than performing an echographic fetus examination. Results
The clitoris is not a flat organ but has three planes—the cross-section, sagittal section, and J Sex Med 2008;5:413–417
414
Buisson et al. revealed [11], made of two clitoral bodies and two bulbs below. It is difficult to make a measure of the bulbs because they are not well limitated and their diameters are rather variable at different levels. The whole forms a double vault above the vaginal plane (Figure 6) [4,6,11]. Above this clitoral bridge, the glans can be seen in median position. The bulbs form two echogenic areas that are rather similar to that of the clitoral bodies. When quiescent, they are more difficult to spot because they are not limited by a tunica albuginea, while the clitoral bodies are [8,9,10]. Between the bulbs and the clitoral bodies, two small anechoic images are well defined and correspond to the vascular
Figure 1 Cross-section the clitoris.
coronal section—are easily revealed [4,6,8] and it is possible to follow the entire clitoris by dragging the probe along one same plane. The cross-section is made possible by placing the probe transversally at the top of the vulva. This section can easily be spotted because of the symmetry of the clitoral bodies. The plane of the right and left clitoral bodies is round, well-defined within their center, the section of each cavernous artery [9]. The cavernous arteries are better visualized in color Doppler. Anterior to the clitoral bodies, in the medium line is the lacunary and vascular structure of the glans. Posteriorly to the clitoral bodies is the pubic symphysis (Figure 1). The cavernous arteries are well visualized with Doppler color (Figure 2). The mean diameter of the clitoral bodies just before their junction was between 7 mm and 11 mm in our series. The clitoral bodies met on the median line and formed the raphe visualized by an hypoechoic line that tightly comes between the joined clitoral bodies (Figure 3) [4,6,8]. In our series, the length of the raphe was between 8 mm and 10 mm. By dragging the probe, the oval-shaped hypoechoic and slightly lacunary glans of the clitoris become visible in the raphe tail (Figure 1) [4,6,8,10]. A color Doppler sonography makes it possible to visualize the cavernous arteries meeting at raphe level into one clitoral artery (Figure 4). A 3D reconstruction shows the joining of the clitoral bodies at raphe level with a vascular glans in caudal position (Figure 5). By tilting the vaginal probe to the front of the clitoris, a coronal plane (more informative) of the clitoris is made possible. The clitoris root is J Sex Med 2008;5:413–417
Figure 2 Cross-section of the clitoris: color Doppler of the cavernous arteries.
Figure 3 Section of the raphe: an hypoechoic line comes between the joined clitoral bodies.
415
Sonography of the Clitoris
The sagittal plane of the clitoris is performed by placing the probe vertically at the base of one of the labia majora. The plane makes it possible to study each right and left clitoral body. They form two
Figure 4 Color Doppler visualizes the cavernous arteries meeting into one clitoral artery. Figure 6 Coronal plane of the clitoris.
Figure 5 3D reconstruction: the joining of the clitoral bodies at raphe level with glans in caudal position.
Figure 7 Coronal plane of the clitoris: Power Doppler reveals the plexus of Kobelt.
lakes of the plexus of Kobelt [10,11]. The plexus of Kobelt are well seen with Dopper energy (Figure 7). Under the top of the vault with two branches made of the bulbs, the urethra plane can be visualized at the anterior face of the vagina which appears like an hypoechogenic area (Figure 8) [4,6]. No glandlike structures surrounding the urethra are visualized [12]. By dragging the probe downwards, the bulbs are revealed in a plane anterior to the clitoral bodies that disappear from the successive planes because they follow the external and posterior path of the ischiopubic branches [4,11]. The elongated and round-shaped bulbs surround the vaginal opening (Figure 9). At the base of each bulb, the oval shape of the vulvovaginal glands is revealed (Figure 10) [9,11].
Figure 8 Coronal section of the clitoris: the top of the vault made of the two bulbs.
J Sex Med 2008;5:413–417
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Buisson et al.
ribbons with a well-defined hypoechoic structure centered on the cavernous arteries (Figures 11 and 12). The clitoral body followed the ischiopubic branch which can be spotted by its linear and high density echo and is located in the slightly more echogenic and heterogeneous tissue of the labium minus [4,6,8–10]. It is not possible to visualize the overall clitoral body in one single plane because of its length, but it is rather easy to follow its shape by
Figure 12 Sagittal section of the cavernous body: Power Doppler of the cavernous artery.
Figure 9 Coronal section of the clitoris: the elongated and round-shaped bulbs surround the vaginal opening.
Figure 13 Sagittal section of the angle of the clitoris.
Figure 10 Coronal section of the clitoris: at the base of the bulbs, the vulvovaginalglands are reavealed.
dragging the probe. Toward the top of the labium minus, the clitoral body thickens and becomes more compact, made a 90-degree forward turn (the angle of the clitoris) (Figure 13) [4]. In our series the length raphe-glans was between 28 mm and 33 mm. With a color or energy Doppler sonography, the cavernous artery can be observed in a ventral direction while it used to be seen in a median or central position (Figure 1). At the end of the clitoris angle, in a more caudal location, the glans is revealed as a round hypoechoic structure with multiple small vascular lacunae. Discussion
Figure 11 Sagittal section of the cavernous body.
J Sex Med 2008;5:413–417
First of all, we decided to focus the study on the unstimulated clitoris because another study is being carried out to evaluate the echoanatomy of the simulated clitoris.
417
Sonography of the Clitoris It is a simple, nonintrusive method because it is an external one (less intrusive than an endovaginal ultrasound). The method is reproductible and gave us three facts: the existence of clitoral tissue, the demonstration, and the measure of the length of the raphe-glans and the measure of the clitoral body diameter. Those facts are very important in the evaluation of sexual mutilation, accidental traumatism of the clitoris, in cases of vulvectomy, or dermatologic pathology. It gives an idea of the importance of the lesion and the way we can manage the surgical treatment. Perhaps a better understanding of this organ might be a begining approach of resolving sexual dysfunction. Conclusion
The sonography is an easy investigational means that is appropriate to the study of the clitoris. The method is simple, nonintrusive, and less expensive than the nuclear magnetic resonance study. These findings open the path to research on clitoral pathology and could make a scientific approach of the female sexual function and dysfunctions possible. Corresponding Author: Odile Buisson, MD, Centre d’échographie Pluridisciplinaire, 20 rue du Docteur Timsit, 78100 Saint-Germain-en-Laye, France. Tel: 33 (0) 1 39 27 42 41; Fax: 33 (0) 1 39 73 10 00; E-mail: [email protected] Conflict of Interest: None declared. Statement of Authorship
Category 1 (a) Conception and Design Dr. Odile Buisson Dr. Pierre Foldes (b) Acquisition of Data Dr. Odile Buisson Dr. Pierre Foldes (c) Analysis and Interpretation of Data Dr. Odile Buisson Dr. Pierre Foldes
Category 2 (a) Drafting the Manuscript Dr. Odile Buisson Dr. Pierre Foldes (b) Revising It for Intellectual Content Dr. Odile Buisson Dr. Pierre Foldes
Category 3 (a) Final Approval of the Completed Manuscript Dr. Odile Buisson Dr. Pierre Foldes
References
1 Deliganis AV, Maravilla KR, Heiman JR, Carter WO, Garland PA, Peterson BT, Hackbert L, Cao Y, Weisskoff RM. Female genitalia: Dynamic MR imaging with use of MS-325 initial experiences evaluating female sexual response. Radiology 2002; 225:791–9. 2 Suh DD, Yang CC, Cao Y, Heiman JR, Garland PA, Maravilla KR. MRI of female genital and pelvic organs during sexual arousal. J Psychosom Obstet gynaecol 2004;25:153–62. 3 Maravilla KR, Cao Y, Heiman JR, Yang C, Garland PA, Peterson BT, Carter WO. Noncontrast dynamic magnetic resonance imaging for quantitative assessment of female sexual arousal. J Urol 2005; 173:162–6. 4 O’Connell HE, Delancey JO. Clitoral anatomy in nulliparous, healthy, premenopausal volunteers using unenhanced magnetic resonance imaging. J Urol 2005;173:2060–3. 5 Deng J, Crouch NS, Creighton SM, Linney AD, Todd-Pokropek A, Rodeck CH. Minimally compressive, three and four dimensional ultrasound imaging ot the clitoris: A feasibility study. Ultrasound Med Biol 2006;32:1479–984. 6 Foldes P, Buisson O. Clitoris and G spot: An intimate affair. Gynecol Obstet Fertil 2007;35:3–5 (Epub 11 January 2007). 7 Rosen R, Brown C, Heiman J, Leiblum S, Meston C, Shabsigh R, Ferguson D, D’agostino R, Jr. The female sexual function index (FSFI): A multidimensional self-report instrument fot the assessment of female sexual function. J Sex Marital Ther 2000; 26:191–208. 8 O’Connell HE, Hutson JM, Anderson CR, Plenter RJ. Anatomical relationship between urethra and clitoris. J Urol 1998;159:1892–7. 9 O’Connell HE, Sanjeevan KV, Hutson JM. Anatomy of the clitoris. J Urol 2005;174:1189–95. 10 Yang CC, Cold CJ, Yilmaz U, Maravilla KR. Sexually responsive vascular tissue of the vulva. BJU Int 2006;97:766–72. 11 Kamina P. Précis d’anatomie clinique, Tome IV ©2005, Editions Maloine, Paris, France. Paris: Dépôt légal; 2005. 12 Wimpissinger F, Stifter K, Grin W, Stackl W. The female prostate revisited: Perineal ultrasound and biochemical studies of female ejaculate. J Sex Med 2007;4:1388–93.
J Sex Med 2008;5:413–417
Sonography of the Clitoris Odile Buisson, MD,* Pierre Foldes, MD,† and Bernard-Jean Paniel, MHD‡ *Centre d’échographie, Saint Germain en Laye, France; †Hôpital de Saint Germain en Laye, Clinique Louis XIV, Saint Germain en Laye, France; ‡Hôpital Intercommunal de Créteil, Service de Gynécologie, Créteil, France DOI: 10.1111/j.1743-6109.2007.00699.x
ABSTRACT
Introduction. The prevalence of invasive procedures in diagnosing female sexual dysfunctions and pathologies is high. There is a need for a less invasive evaluation tool and medical imaging of the clitoris may be a solution. The clitoris has already been studied with nuclear magnetic resonance but there are very few sonographic 2D and 3D studies despite the fact that it is a simple, noninvasive, and inexpensive method. Aim. This study aims at determining the feasibility of using ultrasound (US) techniques to image the clitoris in sufficient detail to permit evaluation of anatomy for possible use in study. Methods. The ultrasounds were performed in five healthy volunteers with the Voluson® GE® Sonography system (GE Healthcare Ultrasound, Zipf, Austria), using one 12-MHz flat probe. Main Outcome Measures. The clitoral body’s diameter, the length of the raphe. Results. The three planes—the cross-section, sagittal section, and coronal section—were revealed making it possible to study the entire organ. Conclusion. The sonography is a simple, inexpensive, noninvasive mean which might help for the evaluation of this organ. Buisson O, Foldes P, and Paniel B-J. Sonography of the clitoris. J Sex Med 2008;5:413–417. Key Words. Clitoris; Clitoral Bodies; Bulbs; Sonography; Ultrasound
Introduction
S
tudies of the clitoris anatomy are still very recent and medical imaging is only beginning. However, it seems that a better knowledge of the clitoral anatomy is a prerequisite for the understanding of pathology of the clitoris. Some nuclear magnetic resonance studies [1–4] have already been published; however, to our knowledge, few ultrasound 2D–3D studies of the clitoris has been published [5–6]. Materials and Methods
The study was conducted on a nonaroused clitoris in five healthy volunteers aged 25 to 45 years. The local ethics committee was not consulted because the volunteers’ motivation was essentially feminist and they felt no need to ask for permission to study their own clitoris. However, the women signed an informed consent form. All of these women have no history of perineal surgery or trauma. Women were not taking birth control pills or receiving © 2007 International Society for Sexual Medicine
hormonal treatments. The female sexual function index scoring [7] revealed no sexual dysfunction and the full scale score range was between 27 and 29. We practiced the sonography between day 2 and day 14 of the menstrual cycle. The ultrasound studies were performed with the Voluson® General Electric® Sonography system (GE Healthcare Ultrasound, Zipf, Austria), a 12-MHz flat probe was used. The volunteers were in a gynecologic position. To insure good skin contact the vulva was covered with a good quantity of sonographic jelly to avoid possible interference from air between the labia. The probe was placed on top of the vulva for the transversal and axial section and on the labia majora for sagittal section. It was not very difficult to slide the probe and to study the entire clitoris in every section: it is far less complicated than performing an echographic fetus examination. Results
The clitoris is not a flat organ but has three planes—the cross-section, sagittal section, and J Sex Med 2008;5:413–417
414
Buisson et al. revealed [11], made of two clitoral bodies and two bulbs below. It is difficult to make a measure of the bulbs because they are not well limitated and their diameters are rather variable at different levels. The whole forms a double vault above the vaginal plane (Figure 6) [4,6,11]. Above this clitoral bridge, the glans can be seen in median position. The bulbs form two echogenic areas that are rather similar to that of the clitoral bodies. When quiescent, they are more difficult to spot because they are not limited by a tunica albuginea, while the clitoral bodies are [8,9,10]. Between the bulbs and the clitoral bodies, two small anechoic images are well defined and correspond to the vascular
Figure 1 Cross-section the clitoris.
coronal section—are easily revealed [4,6,8] and it is possible to follow the entire clitoris by dragging the probe along one same plane. The cross-section is made possible by placing the probe transversally at the top of the vulva. This section can easily be spotted because of the symmetry of the clitoral bodies. The plane of the right and left clitoral bodies is round, well-defined within their center, the section of each cavernous artery [9]. The cavernous arteries are better visualized in color Doppler. Anterior to the clitoral bodies, in the medium line is the lacunary and vascular structure of the glans. Posteriorly to the clitoral bodies is the pubic symphysis (Figure 1). The cavernous arteries are well visualized with Doppler color (Figure 2). The mean diameter of the clitoral bodies just before their junction was between 7 mm and 11 mm in our series. The clitoral bodies met on the median line and formed the raphe visualized by an hypoechoic line that tightly comes between the joined clitoral bodies (Figure 3) [4,6,8]. In our series, the length of the raphe was between 8 mm and 10 mm. By dragging the probe, the oval-shaped hypoechoic and slightly lacunary glans of the clitoris become visible in the raphe tail (Figure 1) [4,6,8,10]. A color Doppler sonography makes it possible to visualize the cavernous arteries meeting at raphe level into one clitoral artery (Figure 4). A 3D reconstruction shows the joining of the clitoral bodies at raphe level with a vascular glans in caudal position (Figure 5). By tilting the vaginal probe to the front of the clitoris, a coronal plane (more informative) of the clitoris is made possible. The clitoris root is J Sex Med 2008;5:413–417
Figure 2 Cross-section of the clitoris: color Doppler of the cavernous arteries.
Figure 3 Section of the raphe: an hypoechoic line comes between the joined clitoral bodies.
415
Sonography of the Clitoris
The sagittal plane of the clitoris is performed by placing the probe vertically at the base of one of the labia majora. The plane makes it possible to study each right and left clitoral body. They form two
Figure 4 Color Doppler visualizes the cavernous arteries meeting into one clitoral artery. Figure 6 Coronal plane of the clitoris.
Figure 5 3D reconstruction: the joining of the clitoral bodies at raphe level with glans in caudal position.
Figure 7 Coronal plane of the clitoris: Power Doppler reveals the plexus of Kobelt.
lakes of the plexus of Kobelt [10,11]. The plexus of Kobelt are well seen with Dopper energy (Figure 7). Under the top of the vault with two branches made of the bulbs, the urethra plane can be visualized at the anterior face of the vagina which appears like an hypoechogenic area (Figure 8) [4,6]. No glandlike structures surrounding the urethra are visualized [12]. By dragging the probe downwards, the bulbs are revealed in a plane anterior to the clitoral bodies that disappear from the successive planes because they follow the external and posterior path of the ischiopubic branches [4,11]. The elongated and round-shaped bulbs surround the vaginal opening (Figure 9). At the base of each bulb, the oval shape of the vulvovaginal glands is revealed (Figure 10) [9,11].
Figure 8 Coronal section of the clitoris: the top of the vault made of the two bulbs.
J Sex Med 2008;5:413–417
416
Buisson et al.
ribbons with a well-defined hypoechoic structure centered on the cavernous arteries (Figures 11 and 12). The clitoral body followed the ischiopubic branch which can be spotted by its linear and high density echo and is located in the slightly more echogenic and heterogeneous tissue of the labium minus [4,6,8–10]. It is not possible to visualize the overall clitoral body in one single plane because of its length, but it is rather easy to follow its shape by
Figure 12 Sagittal section of the cavernous body: Power Doppler of the cavernous artery.
Figure 9 Coronal section of the clitoris: the elongated and round-shaped bulbs surround the vaginal opening.
Figure 13 Sagittal section of the angle of the clitoris.
Figure 10 Coronal section of the clitoris: at the base of the bulbs, the vulvovaginalglands are reavealed.
dragging the probe. Toward the top of the labium minus, the clitoral body thickens and becomes more compact, made a 90-degree forward turn (the angle of the clitoris) (Figure 13) [4]. In our series the length raphe-glans was between 28 mm and 33 mm. With a color or energy Doppler sonography, the cavernous artery can be observed in a ventral direction while it used to be seen in a median or central position (Figure 1). At the end of the clitoris angle, in a more caudal location, the glans is revealed as a round hypoechoic structure with multiple small vascular lacunae. Discussion
Figure 11 Sagittal section of the cavernous body.
J Sex Med 2008;5:413–417
First of all, we decided to focus the study on the unstimulated clitoris because another study is being carried out to evaluate the echoanatomy of the simulated clitoris.
417
Sonography of the Clitoris It is a simple, nonintrusive method because it is an external one (less intrusive than an endovaginal ultrasound). The method is reproductible and gave us three facts: the existence of clitoral tissue, the demonstration, and the measure of the length of the raphe-glans and the measure of the clitoral body diameter. Those facts are very important in the evaluation of sexual mutilation, accidental traumatism of the clitoris, in cases of vulvectomy, or dermatologic pathology. It gives an idea of the importance of the lesion and the way we can manage the surgical treatment. Perhaps a better understanding of this organ might be a begining approach of resolving sexual dysfunction. Conclusion
The sonography is an easy investigational means that is appropriate to the study of the clitoris. The method is simple, nonintrusive, and less expensive than the nuclear magnetic resonance study. These findings open the path to research on clitoral pathology and could make a scientific approach of the female sexual function and dysfunctions possible. Corresponding Author: Odile Buisson, MD, Centre d’échographie Pluridisciplinaire, 20 rue du Docteur Timsit, 78100 Saint-Germain-en-Laye, France. Tel: 33 (0) 1 39 27 42 41; Fax: 33 (0) 1 39 73 10 00; E-mail: [email protected] Conflict of Interest: None declared. Statement of Authorship
Category 1 (a) Conception and Design Dr. Odile Buisson Dr. Pierre Foldes (b) Acquisition of Data Dr. Odile Buisson Dr. Pierre Foldes (c) Analysis and Interpretation of Data Dr. Odile Buisson Dr. Pierre Foldes
Category 2 (a) Drafting the Manuscript Dr. Odile Buisson Dr. Pierre Foldes (b) Revising It for Intellectual Content Dr. Odile Buisson Dr. Pierre Foldes
Category 3 (a) Final Approval of the Completed Manuscript Dr. Odile Buisson Dr. Pierre Foldes
References
1 Deliganis AV, Maravilla KR, Heiman JR, Carter WO, Garland PA, Peterson BT, Hackbert L, Cao Y, Weisskoff RM. Female genitalia: Dynamic MR imaging with use of MS-325 initial experiences evaluating female sexual response. Radiology 2002; 225:791–9. 2 Suh DD, Yang CC, Cao Y, Heiman JR, Garland PA, Maravilla KR. MRI of female genital and pelvic organs during sexual arousal. J Psychosom Obstet gynaecol 2004;25:153–62. 3 Maravilla KR, Cao Y, Heiman JR, Yang C, Garland PA, Peterson BT, Carter WO. Noncontrast dynamic magnetic resonance imaging for quantitative assessment of female sexual arousal. J Urol 2005; 173:162–6. 4 O’Connell HE, Delancey JO. Clitoral anatomy in nulliparous, healthy, premenopausal volunteers using unenhanced magnetic resonance imaging. J Urol 2005;173:2060–3. 5 Deng J, Crouch NS, Creighton SM, Linney AD, Todd-Pokropek A, Rodeck CH. Minimally compressive, three and four dimensional ultrasound imaging ot the clitoris: A feasibility study. Ultrasound Med Biol 2006;32:1479–984. 6 Foldes P, Buisson O. Clitoris and G spot: An intimate affair. Gynecol Obstet Fertil 2007;35:3–5 (Epub 11 January 2007). 7 Rosen R, Brown C, Heiman J, Leiblum S, Meston C, Shabsigh R, Ferguson D, D’agostino R, Jr. The female sexual function index (FSFI): A multidimensional self-report instrument fot the assessment of female sexual function. J Sex Marital Ther 2000; 26:191–208. 8 O’Connell HE, Hutson JM, Anderson CR, Plenter RJ. Anatomical relationship between urethra and clitoris. J Urol 1998;159:1892–7. 9 O’Connell HE, Sanjeevan KV, Hutson JM. Anatomy of the clitoris. J Urol 2005;174:1189–95. 10 Yang CC, Cold CJ, Yilmaz U, Maravilla KR. Sexually responsive vascular tissue of the vulva. BJU Int 2006;97:766–72. 11 Kamina P. Précis d’anatomie clinique, Tome IV ©2005, Editions Maloine, Paris, France. Paris: Dépôt légal; 2005. 12 Wimpissinger F, Stifter K, Grin W, Stackl W. The female prostate revisited: Perineal ultrasound and biochemical studies of female ejaculate. J Sex Med 2007;4:1388–93.
J Sex Med 2008;5:413–417