The G-spot: an observational MRI pilot study

Transcription

1 DOI: / Psychosexual health The G-spot: an observational MRI pilot study YK Maratos, a R Gombergh, a E Cornier, b JP Minart, c N Amoretti, d A Mpotsaris e a Centre d Imagerie Medicale Numerisee (CIMN), Paris, France b Clinique de la Muette, Paris, France c Paris Prevention, Paris, France d Department of Radiology, Centre Hospitalo-Universitaire de Nice, Nice, France e Department of Radiology and Neuroradiology, University Hospital of Cologne, Cologne, Germany Correspondence: A Mpotsaris, University Hospital of Cologne, Department of Radiology and Neuroradiology, Kerpener Str. 62, Cologne, Germany. anastasios.mpotsaris@uk-koeln.de Accepted 8 November Published Online 18 January Objectives To identify a G-spot complex (GSC) in vivo in MRI examinations at 1.5 Tesla field strength. Design Observational study. Setting Single centre. Population Twenty-one consecutive patients (January March 2014). Methods Imaging analysis of routine imaging protocols for usual medical indications with and without concomitant opacification of the vaginal cavity with inert ultrasound gel. The gel distends the otherwise collapsed vaginal walls, allowing for an improved discrimination of anatomic features. The macroscopic and histological results recently derived from the dissections of fresh cadavers by Ostrzenski et al. were translated into imaging characteristics to be expected in the respective MRI sequences (e.g. T1- and T2-weighted) in search of an in vivo correlate of the GSC. Age, menopause status, medical indication and diagnosis were co-variables. Main outcome measures To analyse primarily whether MRI imaging is able to depict a distinct morphological entity in vivo matching the GSC, based on anatomical descriptions published recently. The elaboration of an appropriate MRI-imaging protocol was a secondary aim. Results A total of 21 studies were obtained. A GSC was identified within the anterior vaginal wall in 13/21 patients (62%). In all, 10/ 21 (48%) had vaginal gel opacification. We identified a GSC in 10/ 10 patients (100%) with opacification in all three planes of the T2 images. This was only true for 3/11 cases (27%) without opacification. Conclusions There is evidence for an in vivo morphological correlate to the postmortem anatomical findings of a GSC described by Ostrzenski et al.; its visibility in MRI imaging can be significantly improved with vaginal opacification by ultrasound gel. Keywords Female erectile body, Gr afenberg s zone, G-spot, G-spot anatomy, G-spot MRI, pelvic MRI, vaginal anatomy. Tweetable abstract Identification of G-spot by MRI with vaginal gel-opacification in 13/21 patients. Linked article This article is commented on by KR Wylie, p in this issue. To view this mini commentary visit dx.doi.org/ / Please cite this paper as: Maratos YK, Gombergh R, Cornier E, Minart JP, Amoretti N, Mpotsaris A. The G-spot: an observational MRI pilot study. BJOG 2016;123: Introduction Dating as far back as the 11th century, ancient Indian texts already described an erogenous area of heightened sensitivity, able to induce sexual pleasure in the vagina. 1 In analogy, the Dutch anatomist Regnier de Graaf described in the 17th century a distinct erogenous anatomical area in the anterior vaginal wall 2 ; the term Gr afenberg Spot was coined in the USA in the 1980s by Addiego et al. 3 5 to honor the German physician Ernst Gr afenberg who described an erogenous area located on the anterior vaginal wall in the 1940s and 1950s. Quickly thereafter, the G-spot reached the status of modern myth with the worldwide best seller The G-spot and other recent discoveries about human sexuality by Alice Khan Ladas and Beverly Whipple, which has been fuelling controversy on a regular basis ever since. 6 8 The absence, from a scientific standpoint, of sufficiently accurate or extensive research has been repeatedly acknowledged. 9,10 It was striking to us as radiologists that such a widely discussed matter such as the G-spot has not yet been exclusively and extensively investigated with pelvic MRI, given the quality of detail with modern scanners. As of February 2015 a search in the PubMed database yielded no result for the key words Grafenberg spot AND MRI or Grafenberg spot AND magnetic resonance imaging ; and switching to the abbreviation G-spot AND MRI resulted in a single hit, namely a review by Jannini et al. 11 published in In this review the only reference to the G-spot in pelvic MRI is a study by 1542 ª 2016 Royal College of Obstetricians and Gynaecologists

2 The G-spot: an observational MRI pilot study Schultz et al. 12 in a single subject; furthermore, Jannini et al. 11 claim that Gutman et al., 13 who investigated anatomical relationships between the vaginal apex and the ischial spines and sacrum for nulliparous women with normal support in 11 cases in pelvic MRI, did not find a G- spot. Gutman et al., however, did not investigate a potential imaging correlate of the G-spot nor did they use the terms Grafenberg spot or G-spot in their article. This underlines that MRI imaging data on the presumed anatomical location of the G-spot is currently insufficient at best. From an anatomic standpoint a series of detailed dissections performed on fresh and fixed cadavers by O Connell et al. 14 imply that the majority of current descriptions of female human urethral and genital anatomy are inaccurate and that there are major shortcomings in the published literature. Further research in the same group demonstrated the integral relationships and dynamic interactions between the clitoris, urethra and anterior vaginal wall, 15 whereby MRI imaging favourably complemented the conclusions drawn from the dissectional studies by providing multiplanar depictions in the live state; this was also confirmed by the MRI studies of the clitoral complex by Vaccaro et al. and Oakley et al. 16,17 In particular, MRI helped to demonstrate that the distal vagina and urethra are clearly related, forming a midline core to the clitoris. 15 Histologically, this tissue cluster might be a locus of female sexual function and orgasm, as micro-dissections and immunohistochemical studies have shown differences in innervations of various regions of the vagina, especially in 1/5 partition of the distal anterior wall. 18,19 The anterior wall was more densely innervated compared with biopsy tissues from the posterior wall, and distal areas of the vaginal wall had a greater number of nerve fibres than proximal regions; therefore, Song et al. 19 proposed this part as the correlate of the G-spot in their study. Recently, Ostrzenski et al completed their initial observation in a single dissection by conducting further anatomical investigations on the presence of a G-spot in up to 11 consecutive cadavers. Their protocol was designed as a prospective and descriptive case series. They confirmed the presence of a G-spot complex in all subjects on either the distal vaginal left (more often) or right side from the lateral margin of the urethra, described the histological characteristics and most importantly gave detailed information about the distance from the surrounding anatomical landmarks (e.g. the urethral meatus) for consistent identification of the G-spot. Aim of the study The primary aim of our study was to analyze whether conventional MRI imaging techniques with broadly available scanners at 1.5 Tesla magnetic field strength are able to depict a distinct morphological entity matching the G-spot complex in vivo based on the anatomical descriptions presented recently by Ostrzenski et al. A secondary aim was to elaborate an appropriate MRI imaging protocol for this task. Material and methods We conducted a retrospective observational study of all consecutive female patients who were examined by pelvic MRI with routine imaging protocols for usual medical indications from January to March According to national and institutional regulations, no ethics committee approval was required for this observational study. All patients gave informed consent for the examinations including advanced imaging techniques with standard gadolinium-based contrast agents or vaginal filling with ultrasound gel whenever required by the underlying medical condition. We documented age, parity, menopause status, indication of the examination, technique and protocol (sequences) of the MRI and the resulting diagnosis. All examinations were performed on the same 1.5 Tesla MRI (GE Signa HDxt; General Electric Healthcare, Amersham, Bucks, UK) in conjunction with a standard body antenna and analysed by the same board-certified senior radiologist. Statistical analysis Patient data were analysed after pseudonymisation of identity-related fields such as name and date of birth. Clinical information was obtained from the medical records and relevant details were entered into an EXCEL worksheet (Excel â 05; Microsoft Corp., Redmond, WA, USA). The statistical analysis was carried out using the commercially available SPSS â Statistical Software (SPSS 11.0 for Windows, IBM, Ehningen, Germany) and the R statistical software environment version Qualitative variables were described in terms of their frequency (absolute numbers and percentages) and proportions compared using Fisher s exact test (chi-squared). Quantitative variables were analysed with Student s t-test and Mann Whitney U-test for independent data. Statistical significance was set at P-values Imaging protocol and technique Our MRI study protocol included T2 acquisitions in three planes in all patients with 3-mm slice thickness. In three cases we also performed three-dimensional T2-weighted imaging. Depending on the underlying condition we utilised T1 sequences with and without fat suppression, diffusion imaging in an axial plane, and T1 axial and sagittal planes after injection of contrast medium with 3-mm slice thickness. These sequences were obtained in a standardised manner with standardised plane orientations in all patients. ª 2016 Royal College of Obstetricians and Gynaecologists 1543

3 Maratos et al. Depending on the indication we also opacified the vagina with ultrasound gel which is routinely done while looking for signs of endometriosis or to perform dynamic studies to rule out organ descent or uterine ptosis (e.g. in cases of urinary or rectal incontinence). The gel has a distentional effect on the vaginal walls allowing for an improved discrimination of the distinct anatomical findings compared to a collapsed vagina; it does not create artifacts and is visualised with a water-like hyperintense T2 signal. 23 Imaging analysis Put simply, the histological composition of any tissue in the human body renders a specific signal in MRI imaging according to pre-defined sequence parameters, which is then translated into a greyscale image that can be interpreted by the physician. MRI imaging capabilities are limited compared with histological processing of tissue. What can be seen depends on the chosen sequence and is influenced by a broad range of technical parameters. 24 Thus, we did not aim at a structural discrimination at the level of the nervous tissue but instead at the complex as a whole, especially in conjunction with the entangled vascular structures which render a sufficient MR image. In the search for a histological entity that has not yet been described in MRI imaging one has carefully to interpret the histological knowledge gained from the dissection studies while keeping potential differences in tissue presentation between in vivo and postmortem conditions in mind. Ostrzenski et al. 20,21 only dissected cadavers within <48 hours from death; at the time of the macro- and micro-dissection of the cadavers, there were no means of artificial preservation except for refrigeration. Thus, significant changes of the macroscopic anatomical measurements (e.g. due to bloating or dehydration and shrinking) of the soft tissues in the vicinity of the vagina are not to be expected in that period of time. According to the description of Ostrzenski et al. 21 we acted on the following assumptions: 1 The G-spot was a neurovascular complex embedded within a fibroadipose tissue bed, housing a large number of peripheral nerve bundles and a neuroganglion. Overlying circular and longitudinal muscles covered the neurovascular complex. The vascular component comprised large vein-like vessels and smaller feeding arteries, which were tangled together and occasionally featured arteriovenous interconnections. 2 The G-spot complex in fresh human female cadavers was embedded in the anterior vaginal wall about 45 mm on average from the urethral meatus. 3 The location of the G-spot complex in relation to the urethral borders showed variance and was identified either on the left-lateral or right-lateral portion. In the coronal plane the shape of the G-spot was cylindrical, comprising a large head portion, a thinner middle part and becoming narrower at the lower border (the G-spot tail), creating a funnel-shape fused with vessels. 4 The G-spot complex varied in length, on average 7 mm. Consequently, from a radiologist s point of view we would expect to find a structure that would be hyperintense in relation to the surrounding muscular tissue in T2. It would have regular borders and would be more concave in the axial plane and cylindrical in the coronal plane in all sequences. In T1 with fat saturation we would expect a hypointense signal due to the suppression of the adipose component of the complex. Based on the histological finding of surrounding entangled small arteries with relatively large veins with occasional arterio-venous shunts, one would expect an enhancement after systemic intravenous contrast injection, albeit not in every case, as the signal could be influenced by factors such as contrast agent dose, subject age, co-morbidity and local pooling effects, e.g. sexual arousal, which have been described for the clitoral region in MRI exams. 27 Anatomical measurements Once we identified a protrusion in the anterior vaginal wall we measured the following findings: 1 The thickness of the complex head portion in a transversal manner (left to right; thickness in the plane between the femoral bones). 2 The thickness of the complex-head itself in an anteriorposterior manner. 3 The distance of the external anterior border of the complex-head to the urethra in an axial plane and anteriorposterior way. 4 The height of the complex in a cranial-caudal extension; from the complex-head to its tail. 5 The distance from the vulvar meatus to the complex-tail. Ostrzenski et al. measured from the urethral meatus to the tail of the complex. In standard imaging studies the urethral meatus is not visible (without opacification, as we performed a non-invasive examination), so in analogy to the anatomical study we measured from the vulvar meatus to the tail (end point) of the complex, supposing that the urethral meatus and the vulvar meatus are almost at the same height. Results Study population Twenty-one consecutive MRI studies of patients years of age (mean 46, 15.8 SD) were obtained. Ultrasound gel opacification of the vagina was carried out in 10 cases (48%) and intravenous contrast agent in 14 (67%). Ten patients (48%) were in menopause. Six were nullipara (29%) ª 2016 Royal College of Obstetricians and Gynaecologists

4 The G-spot: an observational MRI pilot study Table 1. Patients with no gel opacification of the vagina Patient number Age Menopause status ( /+) Parity Indication for MRI exam Thin slice (3 mm) 3D T2 sequence Standard slice (5 mm) multiplanar T2 sequence Vaginal opacification with gel Radiological diagnosis Metrorrhagia + Normal exam 2 39 n.a. Pain + Endometriosis and adenomyosis Pain + Endometriosis and adenomyosis Pain Endometriosis and adenomyosis n.a. Pain + Normal exam n.a. Pain + Normal exam n.a. Metrorrhagia + + Polyp and adenomyosis n.a. Tumour suspicion + Fibroma and ovary cyst Pain and metrorrhagia + Polyp, endometriosis, adenomyosis and fibroma Pain + + Perineal collections and fistula n.a. Incontinence Lesion of anal sphincter Tumor suspicion + Endometriosis and adenomyosis n.a. Pain + Normal exam Pain + + Endometriosis and adenomyosis n.a. Pain + + Adenomyosis n.a. Metrorrhagia + Adenomyosis Metrorrhagia + + Endometrial retention Infertility + + Hydrosalpynx n.a. Pain + + Endometriosis and adenomyosis n.a. Metrorrhagia + Normal exam Incontinence Normal exam n.a., not available; + applicable; not applicable; MRI, magnetic resonance imaging; 3D, three-dimensional. The most frequent indication was pelvic pain (10/21; 48%), followed by intracyclic menstrual bleeding (metrorrhagia) (6/21; 29%) and incontinence (2/21; 10%). The study population data including indications and MRI sequences are summarised in Table 1. In 11 of the 21 patients (52%) we used a standard pelvic MRI protocol without gel opacification, depicting a collapsed vagina. In eight (73%) we were not able to identify a distinct anatomical complex matching the pre-defined G- spot criteria in the vicinity of the anterior vaginal wall. T2- weighted axial images depicted in three patients (27%) a thickening within the anterior vaginal wall posterior to the peri-urethral muscles and meatus with a relatively hyperintense signal compared with the muscle tissue. Its size was significant enough to distinguish it from the slightly more hypointense vaginal wall and to identify it as the head portion of the complex, which was the largest part in the postmortem study by Ostrzenski et al. Figure 1a shows an anatomical overview (T2-weighted) of the pelvic region in the axial plane; the anatomical landmarks are marked with capital letters. Figure 1b is an enlargement of the perivaginal area between the urethra and the anal region in the identical axial plane of the same patient. It depicts a large median thickening dorsal of the urethra and underneath the mucosa of the anterior vaginal wall, corresponding to the G-spot complex. The analysis of the sagittal and coronal T2 images was more difficult due to the collapse of the vaginal structures and did not provide additional information in the majority of cases. The G-spot complex could be visualised in the sagittal plane in those three patients in whom it was clearly visible axially. Figure 1c depicts the corresponding sagittal plane of the same patient shown in Figure 1a and b. Ten of the 21 patients (48%) had a gel opacification of the vagina. The distention of the vaginal walls by the ultrasound gel counteracted their natural tendency to collapse. It also created a strong homogeneous contrast to the vaginal wall portions, yielding a hyperintense, fluid-like signal in T2. We were able to identify a distinct anatomical entity matching the pre-defined G-spot complex criteria in the vicinity of the anterior vaginal wall in ten patients (100%) in all three planes of the T2 images. The vaginal opacification technique led to a statistically significant higher detection rate compared with non-opacified studies (P < 0.01; Fisher s exact test). Figure 2(a,b) illustrates the typical MRI findings. ª 2016 Royal College of Obstetricians and Gynaecologists 1545

5 Maratos et al. (a) (a) (b) (b) (c) Figure 1. (a) Axial T2-weighted MRI image of the pelvis without fat saturation and without gel opacification of the vagina. A, ischial tuberosity; B, anal region; C, urethra; D, pubic symphysis. (b) Magnification, axial T2-weighted MRI image without fat saturation and without gel opacification of the vagina. *Centre of the medially located G-spot complex. A, Arrow marking the anterior vaginal wall. B, Arrow pointing at the posterior vaginal wall. (c) Sagittal T2-weighted MRI image of the pelvic region without fat saturation and without gel opacification of the vagina. A, anal region; B, urethra; C, rectum; D, os pubis; E, bladder; F, uterus; G, S1 sacral vertebra. Arrows marked with *(asterisk) show the cranial and caudal borders of the G-spot complex. Arrow marked with + (plus) points to the collapsed vaginal walls. Overall, a G-spot complex could be identified in 13 patients (62%). The position of the G-spot complex was variable with five cases (38%) on the right side, three (24%) on the left side and five (38%) in a medial position. In one case (No. 11) we observed an atypical posterior Figure 2. (a, b) Axial and sagittal T2-weighted image with vaginal distension by ultrasound gel of a 36-year-old nullipara with a large uterine fibroma. Depiction of a protruding tissue complex with moderately hyperintense T2 signal resulting in a thickening/ballooning within the anterior vaginal wall posterior to the urethra. (a) A, ischial tuberosity; B, anal region; C, distended vaginal cavity with ultrasound gel; D, urethra; E, symphysis. Arrows marked with *(asterisk) point to the G-spot complex. (b) A, anal region; B, symphysis; C, distended vaginal cavity with ultrasound gel; D, bladder; E, uterine fibroma; F, uterus; G, S1 sacral vertebra. Arrows marked with *(asterisk) point to the G-spot complex. vaginal wall ballooning. This case was excluded for the measurement of the distance between the urethra and the G-spot complex. It was included in the remainder of measurements. The mean transverse diameter (axial plane) of the G-spot complex was 15.9 mm (4.1 SD). The mean thickness of the complex amounted to 5.2 mm (1.6 SD). The distance between the urethra and the complex (axial plane) was 5.3 mm (1.5 SD). The mean height of the G-spot complex was 15.9 mm (6.9 SD). The distance from the urethral meatus to the G-spot complex tail was 23.6 mm (7.1 SD). Table 2 gives an overview of the measurements. In comparison with the measurements presented in the study of Ostrzenski et al., significant differences were observed pertaining to the distance of the urethral meatus 1546 ª 2016 Royal College of Obstetricians and Gynaecologists

6 The G-spot: an observational MRI pilot study Table 2. Anatomical results in all patients with identifiable G-spot complex Patient number Vaginal opacification with gel Anatomical position of GSC in relation to urethral axis Transverse diameter of GSC (axial plane, from left to right; mm) Thickness of GSC (axial plane, antero-posterior; mm) Distance urethra to GSC (axial plane; mm) Height of GSC (cranio-caudal; mm) Distance urethral meatus to GSC (mm) 1 Left Medial Right Right Right Atypical posterior left Atypical posterior localization Medial Medial Left Right Right and left Medial Right GSC, G-spot complex; + applicable; not applicable. Table 3. Influence of co-variables on the presence of a G-spot complex Study Mean distance urethral meatus to GSC (mm) Mean height of GSC (cranio-caudal; mm) Mean thickness of GSC (axial plane, antero-posterior; mm) Patients Maratos et al., present study Ostrzenski et al P-value <0.001 <0.001 <0.001 GSC, G-spot complex. to the G-spot complex, its height and thickness. Table 3 compares our key anatomical findings with those of Ostrzenski et al. 21 Univariate statistical analysis of the role of the co-variables patient age, menopause and parity pertaining to the presence of a discernible G-spot complex did not yield a statistically significant result (P > 0.05; Mann Whitney U-test). Discussion Main findings The question of whether the G-spot does exist has raised controversy ever since it was announced. The long-lasting lack of profound anatomical, physiological and imaging evidence for its existence has been addressed in recent times in part by the dissectional study of Ostrzenski et al., whose descriptions motivated us as radiologists to investigate their findings with up-to-date MRI modalities; a literature research concerning MRI-based evidence for the existence of the G-spot yielded no satisfactory results. 11,20,21,28 We were able to identify a morphological entity in our MRI exams with a consistent and reproducible signal quality in T1- and T2-weighted sequences in the majority (>60%) of patients that was correlated with the descriptive anatomical measurements of Ostrzenski et al. Strengths and limitations Drawbacks of our study are the retrospective design as an observational study based on regular protocols for other pelvic diseases. The small size of the cohort is expected to have had a negative influence on the statistical power of ª 2016 Royal College of Obstetricians and Gynaecologists 1547

7 Maratos et al. the univariate analysis, which failed to prove a relationship between the co-variables such as age and menopause, and the visibility of the complex. These factors should be reproduced in larger prospective and preferably controlled cohorts. The age range of the population and the lack of any sexual history of the enrolled women is another limitation. As a result, we have no evidence that they ever had so-called G-spot orgasms from penile-vaginal intercourse or by digital stimulation of the anterior vaginal wall. Interpretation The significantly greater anatomical dimensions found in our cohort are explained by the different underlying definitions; the numbers given by Ostrzenski et al. refer to the histological entity of the G-spot consisting of the nervous tissue and its associated ganglion embedded in adipose tissue. As these structures cannot be separated with the MRI protocol utilised, we measured the whole complex including the entangling vasculature, which we could discriminate from the signal of the adjacent vaginal wall. Pertaining to the mean distance of the complex to the urethral meatus (23.6 versus 45 mm in Ostrzenski et al.), the difference could be explained by two confounders: a vascular complex might be larger in vivo while perfused with blood, meaning that its distance to the urethral meatus would decrease. Another reason might be the variance observed in the measurements in both studies, which could only be clarified in a larger cohort. Furthermore, to the best of our knowledge, the method of applying an inert and inexpensive ultrasound gel has not been used in conjunction with the search for the G-spot complex, although its value for enhancing the discernibility of the anatomical structures in the pelvic region is widely known and utilised in routine protocols for certain clinical indications. 23 The resulting distension of the vaginal wall and the homogeneous signal of the gel in the cavity allowed for a statistically significant higher detection rate of the G- spot complex in the anatomical vicinity described by Ostrzenski et al. as compared with the standard technique without vaginal filling, reaching as high as 100%. We were only able to discern the complex in patients without filling when its size was above average, as was found in 27% of the cases without filling. A regular pelvic MRI protocol including T2-weighted thin sliced image acquisitions in three planes or alternatively three-dimensional sequences permits the detection of the complex in conjunction with a vaginal filling, even without contrast agent application. However, Deliganis et al. 27 were able to demonstrate that the uptake of contrast agent in the clitoral region depended on the applied dose as well as the sexual state of the patient. We did not control for these variables in our retrospective study about the G-spot complex but we support the idea of a contrast agent application under controlled conditions in a prospective study. Ostrzenski et al. 21 have presented evidence that the vascular component of the complex has the ability to grow up to approximately five times in size and that there are microscopically visible arterio-venous shunts which might, in our opinion, culminate in a pooling of contrast agent with discrimination of the venous structures of the tail of the complex. To date, several profound ultrasound studies have been conducted, focusing on the dynamic relationship of the clitoral complex, the urethra and the anterior vaginal wall, either during finger penetration or sexual intercourse in volunteer couples These studies have contributed to the concept of the clitourethrovaginal complex, which goes beyond the search for a single G-spot, stressing the role of these anatomic structures in a morphofunctional interplay which may induce female orgasm. 32 We see the present study as another piece of the puzzle, promoting the usefulness of state-of-the-art MRI imaging in shedding light on this complex matter. The idea of a G-spot does not contradict this complex interplay, and could be as our pilot study suggests part of it, although we were not able to find a morphologic correlate in all of the subjects, which might be an important finding by itself. Conclusion The present in vivo MR-imaging pilot study presents evidence for a distinct morphological correlate to the recently introduced anatomical evidence of a G-spot complex as described by Ostrzenski et al. in their series of dissections. Neither special scanning equipment or special MR protocols are required to find this complex. The visibility of the complex can be significantly improved with vaginal distention using ultrasound gel. Further MR-imaging studies are warranted to elucidate the value of non-invasive imaging for the treatment of associated pathological entities such as sexual dysfunction. Disclosure of interests Full disclosure of interests available to view online as supporting information. Contribution to authorship MYK: Imaging acquisition & analysis, data sampling, data statistics, writing, editing. GR, CE, AN: Imaging analysis, data sampling, data statistics, writing, editing. MJP: Literature review, data sampling, data statistics, writing, editing. AM: Imaging analysis, literature review, data statistics, writing, editing, conceptual design. Details of ethics approval According to national guidelines, no ethics approval was necessary due to the retrospective, observational character of the study ª 2016 Royal College of Obstetricians and Gynaecologists

8 The G-spot: an observational MRI pilot study Funding None. Acknowledgements None. & References 1 Syed R. Knowledge of the Gräfenberg zone and female ejaculation in ancient Indian sexual science. A medical history contribution. Sudhoffs Arch 1999;83: Jocelyn HD, Setchell BP. Regnier de Graaf on the human reproductive organs. An annotated translation of Tractatus de Virorum Organis Generationi Inservientibus (1668) and De Mulierub Organis Generationi Inservientibus Tractatus Novus (1962). J Reprod Fertil Suppl 1972;17: Addiego F, Belzer EG Jr, Comolli J, Moger W, Perry JD, Whipple B. Female ejaculation: a case study. J Sex Res 1981;17: Grafenberg E, Dickinson RL. Conception control by plastic cervix cap. West J Surg Obstet Gynecol 1944;12: Gr afenberg E. The role of the urethra in female orgasm. Int J Sexol 1950;3: Ladas AK, Whipple B, Perry JD. The G Spot and Other Recent Discoveries about Human Sexuality. New York: Holt Rinehart and Winston, Miller CE. G-spot: The facts to the fantasy. BJOG 2014;121: Puppo V. The G-spot does not exist. BJOG 2014;121: Kilchevsky A, Vardi Y, Lowenstein L, Gruenwald I. Is the female G- spot truly a distinct anatomic entity? J Sex Med 2012;9: Hines TM. The G-spot: a modern gynecologic myth. Am J Obstet Gynecol 2001;185: Jannini EA, Whipple B, Kingsberg SA, Buisson O, Foldes P, Vardi Y. Who s afraid of the G-spot? J Sex Med 2010;7: Schultz WW, van Andel P, Sabelis I, Mooyaart E. Magnetic resonance imaging of male and female genitals during coitus and female sexual arousal. BMJ 1999;319: Gutman RE, Pannu HK, Cundiff GW, Melick CF, Siddique SA, Handa VL. Anatomic relationship between the vaginal apex and the bony architecture of the pelvis: a magnetic resonance imaging evaluation. Am J Obstet Gynecol 2005;192: O Connell HE, Hutson JM, Anderson CR, Plenter RJ. Anatomical relationship between urethra and clitoris. J Urol 1998;159: O Connell HE, Sanjeevan KV, Hutson JM. Anatomy of the clitoris. J Urol 2005;174: Oakley SH, Vaccaro CM, Crisp CC, Estanol MV, Fellner AN, Kleeman SD, et al. Clitoral size and location in relation to sexual function using pelvic MRI. J Sex Med 2014;11: Vaccaro CM, Fellner AN, Pauls RN. Female sexual function and the clitoral complex using pelvic MRI assessment. Eur J Obstet Gynecol Reprod Biol 2014;180: Hilliges M, Falconer C, Ekman-Ordeberg G, Johansson O. Innervation of the human vaginal mucosa as revealed by PGP 9.5 immunohistochemistry. Acta Anat (Basel) 1995;153: Song YB, Hwang K, Kim DJ, Han SH. Innervation of vagina: microdissection and immunohistochemical study. J Sex Marital Ther 2009;35: Ostrzenski A. G-spot anatomy: a new discovery. J Sex Med 2012;9: Ostrzenski A, Krajewski P, Ganjei-Azar P, Wasiutynski AJ, Scheinberg MN, Tarka S, et al. Verification of the anatomy and newly discovered histology of the G-spot complex. BJOG 2014;121: Ostrzenski A. Anatomic documentation of the G-spot complex role in the genesis of anterior vaginal wall ballooning. Eur J Obstet Gynecol Reprod Biol 2014;180: Chassang M, Novellas S, Bloch-Marcotte C, Delotte J, Toullalan O, Bongain A, et al. Utility of vaginal and rectal contrast medium in MRI for the detection of deep pelvic endometriosis. Eur Radiol 2010;20: Pooley RA. AAPM/RSNA physics tutorial for residents: fundamental physics of MR imaging. Radiographics 2005;25: Haglund WD, Sorg MH. Forensic Taphonomy: The Postmortem Fate of Human Remains. Boca Raton: CRC Press (Taylor & Francis), Micozzi MS. Postmortem change in human and animal remains: a systematic approach. Springfield: CC Thomas Publishers; Deliganis AV, Maravilla KR, Heiman JR, Carter WO, Garland PA, Peterson BT, et al. Female genitalia: dynamic MR imaging with use of MS-325 initial experiences evaluating female sexual response. Radiology 2002;225: Hines T, Kilchevsky A. The G-spot discovered? Comments on Ostrzenski s article. J Sex Med 2013;10: Foldes P, Buisson O. The clitoral complex: a dynamic sonographic study. J Sex Med 2009;6: Buisson O, Foldes P, Jannini E, Mimoun S. Coitus as revealed by ultrasound in one volunteer couple. J Sex Med 2010;7: Buisson O, Jannini EA. Pilot echographic study of the differences in clitoral involvement following clitoral or vaginal sexual stimulation. J Sex Med 2013;10: Jannini EA, Buisson O, Rubio-Casillas A. Beyond the G-spot: clitourethrovaginal complex anatomy in female orgasm. Nat Rev Urol 2014;11: ª 2016 Royal College of Obstetricians and Gynaecologists 1549