International Journal of Impotence Research (2005) 17, 121–126 & 2005 Nature Publishing Group All rights reserved 0955-9930/05 $30.00 www.nature.com/ijir Response of the internal reproductive organs to clitoral stimulation: The clitorouterine reflex A Shafik1*, O El-Sibai2, R Mostafa3, AA Shafik1 and I Ahmed1 1Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo, Egypt; 2Department of Surgery, Faculty of Medicine, Menoufia University, Shebin-el-Kom, Egypt; and 3Department of Physiology, Faculty of Medicine, Zagazig University, Benha, Egypt We investigated hypothesis that uterine erection, elevation and enlargement during sexual response are reflex and result from penis buffeting the glans clitoris (GC). In 23 healthy women, two recording electrodes were applied to the uterine mucosa and one to cervix uteri (CU). GC was stimulated electrically and mechanically by pencil electrode. The uterine and CU pressures were measured. Tests were repeated after anesthetization of the uterus or GC. Uterine electrodes recorded slow waves, followed by random bursts of action potentials (APs). No waves registered from CU. Electrical or mechanical GC stimulation eliminated uterine electric waves, but anesthetized GC did not, nor did GC stimulation while the uterus anesthetized. Uterine pressure declined on electrical or mechanical stimulation. Results suggest presence of reproducible reflex relationship between GC and the uterus, we call ‘clitorouterine reflex’. GC buffeting seems to evoke reflex and initiate uterine responses. Reflex may prove of diagnostic significance in sexual disorders. International Journal of Impotence Research (2005) 17, 121–126. doi:10.1038/sj.ijir.3901278 Published online 28 October 2004 Keywords: cervix uteri; uterus; clitoris; slow waves; action potentials; sexual disorders Introduction elongation of the vagina. The uterus rises in the pelvis from its anteverted and anteflexed position and the cervix moves away from the posterior The reactions of the female reproductive organs vaginal wall. The uterus enlarges by as much as during the sexual response cycle have been studied 1–6 50%. The cause of uterine erection and elevation by many investigators. Sexual stimulation causes is not exactly known;2 some theories have tried changes in the external and internal reproductive 2,3,7,8 to explain these changes during sexual stimula- organs of the woman. The labia majora straddle tion proposing that they could be due to vasocon- apart exposing the vaginal introitus. With continued gestion in the true pelvis or to neuronally produced excitation, the labia majora and minora become contraction of the smooth musculature in the thickened due to venous congestion. Glans clitoris ligaments that support the uterus.2 (GC) also swells and increases in both length and We hypothesized that the uterine changes hap- thickness. These changes in the external reproduc- pening during sexual stimulation are reflex in tive organs are suggested to be either brought about 2,9–12 nature and occur as a result of penile buffeting of reflexly or to represent a psychogenic response. the GC. This hypothesis was investigated in the Likewise, the internal reproductive organs of the current communication. woman undergo changes during the sexual response cycle.2–4 These changes comprise vaginal transduc- tion of a mucoid fluid as well as expansion and Materials and methods *Correspondence: A Shafik, Department of Surgery and Experimental Research, Cairo University, 2 Talaat Harb Subject Street, Cairo 11121, Egypt. E-mail: [email protected] Received 27 January 2004; revised 16 June 2004; accepted The study comprised 23 healthy female volunteers 19 August 2004 with a mean age of 36.776.3 standard deviation Clitorouterine reflex A Shafik et al 122 (s.d.) y (range 28–44). The women were recruited GC stimulation. GC was stimulated both electri- during the proliferative phase of the menstrual cally and mechanically. Electric stimulation was cycle. They were sexually active, had normal performed with a surface electrode (Vickers Medi- menses and no gynecologic complaint in the past cal, Medelec, Woking, UK) applied to the GC and or at the time of enrolment. A total of 10 were fixed by electrode gel. Mechanical stimulation was nulliparous and 13 multiparous with normal vaginal carried out with a pencil electrode consisting of a deliveries. Physical examination including gyneco- solid steel rod, 15 cm long and 5 mm in diameter. To logic and neurologic assessment had normal find- avoid injury to the GC, the distal end of the ings. Sonograms showed normal genitourinary electrode was covered for about 2 cm by a polyvinyl organs. Women with vaginal discharge, cervical sponge which was fashioned like a cone to simulate erosions or sonographic lesions were excluded from the shape of the glans penis. The response of uterus the study. The subjects were fully informed about and CU to gentle stroking of the GC by the pencil the nature of the study, the tests to be performed and electrode was recorded. The GC stroking by the their role in the study. The study was approved by pencil electrode intended to simulate GC buffeting the Review Board of the Cairo University Faculty of by the erect penis during coitus. It was performed by Medicine and its Ethics Committee. one investigator in all of the examined women. In all, 20 gentle GC strokes were made for each subject. The test was repeated at least twice in the individual subject. Methods The response of the uterus to electrical and Manometric studies. The uterine and CU pressures mechanical stimulation of the GC was determined. were measured by a manometric tube of a 0.5 mm inner and a 1 mm outer diameter, with two side ports, perfused with normal saline at a rate of 1.6 ml/ min by a pneumohydraulic perfusion system (Arn- Electromyographic (EMG) studies. The procedure dorfer, Medical Specialities, Greendale, WI, USA), A was carried out without sedation on an outpatient vaginal speculum was inserted into the vagina to basis. However, some women, especially the nulli- expose the CU. One lubricated tube was introduced parous, were given intravenous diazepam (10 mg; 4–5 cm into the uterine cavity and another one into Hoffman La Roche, Basle, Switzerland) for sedation the CU. They were connected to a strain gauge during cervical dilatation. With the women in the pressure transducer (Statham 230B, Oxnard, CA, lithotomy position, a self-retaining speculum was USA). We started recording the uterine electric introduced into the vagina. Cervical dilation was activity and pressure 30 min after the electrodes performed with Hegar’s dilators in the sizes from 2/5 and the manometric tubes had been applied to the to 3/6 mm. The uterine electric activity was recorded uterus and CU. During this half-hour the uterus by means of a 4F catheter attached to the uterine would have adapted to these devices. At least two wall by suction to a negative pressure of 20 cmH O 2 recording sessions of 60 min each were performed that was maintained during the test. The myo- for every woman. electric activity was recorded by a monopolar silver–silver chloride electrode, 0.25 mm in dia- meter and situated 1 cm from the tip of the catheter (Smith Kline-Becham, Los Angeles, CA, USA). The Clitoral and uterine anesthetization. To study protruding part of the electrode lay in contact with whether the uterine response to clitoral stimulation the endometrium, thus acting as a surface electrode. was a direct or a reflex action, GC stimulation was Three electrodes were applied to the uterus: two performed after individual anesthetization of the to the uterine and one to the cervix uteri (CU) uterus and GC. GC was anesthetized by means of mucosa. The two uterine electrodes were introduced xylocaine gel (Astra, So¨derta¨lje, Sweden). At 20 min through the CU to be attached by suction to the following gel application, the response of the uterus mucosa of the uterine wall, one electrode above the to GC electrical and mechanical stimulation was other and 2 cm apart. The third electrode was recorded. After 3 h later when the anesthetic applied to the cervical mucosa at about the middle response had disappeared, the uterine response to of the cervical canal. The reference electrode was a GC stimulation was registered. The test was re- metal disk applied to the skin of the abdomen. The peated using bland gel instead of xylocaine gel. On signals detected by the electrodes were amplified another day, the uterus was anesthetized by instil- using an AC amplifier with a frequency response ling 10 ml of 2% xylocaine, added to 10 ml of normal within 73 dB from 0.016 Hz to 1 kHz and were saline, into the uterine cavity through the CU. The displayed on a recorder at a sensitivity of 1 mV/cm. uterine response to GC stimulation after 20 min and A strain gauge respiration transducer was attached after 3 h was recorded. The test was repeated using to the thoracic wall to exclude respiratory artifacts. normal saline instead of xylocaine. International Journal of Impotence Research Clitorouterine reflex A Shafik et al 123 The results were analyzed statistically using the Student’s t-test. Values were given as the mean7s.d. Differences assumed significance at Po0.05. Results All the women finished the tests without complica- Figure 2 Electrohysterogram showing disappearance of the tions during or after the test performance and were uterine electric waves (U) on electrical stimulation of the glans evaluated. clitoris. m ¼ stimulation; C ¼ cervical waves. The suction electrodes were atraumatic to the uterine or cervical wall. They were easy to apply, were stable and not dislodged as long as the already mentioned suction pressure was maintained. Dis- lodgment of an electrode would have been recogniz- able from loosening of the catheter. Electromyographic recording Slow waves (SWs) were recorded from the two Figure 3 Electrohysterogram showing appearance of occasional uterine slow waves (U) on electrical stimulation of the glans electrodes applied to the uterus.