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Cervix
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<h2 id="structure">Structure</h2> <p>The cervix is part of the <a href="/facts/Female_reproductive_system/9ebPetXh">female reproductive system</a>. Around 2–3 centimetres (0.8–1.2 in) in length,<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> it is the lower, narrower part of the uterus continuous above with the broader upper part—or body—of the uterus.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> The lower end of the cervix bulges through the anterior wall of the vagina, and is referred to as the vaginal portion of cervix (or ectocervix) while the rest of the cervix above the vagina is called the <a href="/facts/Supravaginal_portion_of_cervix/C79Muv31">supravaginal portion of cervix</a>.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> A central canal, known as the <a href="/facts/Canal_of_the_cervix/mX2gd3vU">cervical canal</a>, runs along its length and connects the <a href="/facts/Cavity_of_the_body_of_the_uterus/m8fXEvAy">cavity of the body of the uterus</a> with the lumen of the vagina.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> The openings are known as the <a href="/facts/Internal_os/mX2gd3vU">internal os</a> and <a href="/facts/External_orifice_of_the_uterus/mX2gd3vU">external orifice of the uterus</a> (or external os), respectively.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> The mucosa lining the cervical canal is known as the <a href="/facts/Endocervix/mX2gd3vU">endocervix</a>,<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> and the mucosa covering the ectocervix is known as the exocervix.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> The cervix has an inner mucosal layer, a thick layer of <a href="/facts/Smooth_muscle/mpcpTsHp">smooth muscle</a>, and posteriorly the supravaginal portion has a <a href="/facts/Serosal/vj8eDs43">serosal</a> covering consisting of connective tissue and overlying <a href="/facts/Peritoneum/BotJhUr0">peritoneum</a>.<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> </p> <p>In front of the upper part of the cervix lies the <a href="/facts/Urinary_bladder/g8Khaf7A">bladder</a>, separated from it by cellular connective tissue known as <a href="/facts/Parametrium/TvTf4ljE">parametrium</a>, which also extends over the sides of the cervix.<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a> To the rear, the supravaginal cervix is covered by peritoneum, which runs onto the back of the vaginal wall and then turns upwards and onto the <a href="/facts/Rectum/caqqyk2e">rectum</a>, forming the <a href="/facts/Recto-uterine_pouch/sMuCsL9m">recto-uterine pouch</a>.<a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a> The cervix is more tightly connected to surrounding structures than the rest of the uterus.<a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a> </p><p>The cervical canal varies greatly in length and width between women or throughout a woman's life,<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> and it can measure 8 mm (0.3 inch) at its widest diameter in <a href="/facts/Premenopause/b3Fz6NHb">premenopausal</a> adults.<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a> It is wider in the middle and narrower at each end. The anterior and posterior walls of the canal each have a vertical fold, from which ridges run diagonally upwards and laterally. These are known as <i>palmate folds</i>, due to their resemblance to a palm leaf. The anterior and posterior ridges are arranged so they interlock with each other and close the canal. They are often effaced after pregnancy.<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a> </p><p>The ectocervix (also known as the vaginal portion of the cervix) has a convex, elliptical shape and projects into the cervix between the anterior and posterior <a href="/facts/Vaginal_fornix/zInVL1bV">vaginal fornices</a>. On the rounded part of the ectocervix is a small, depressed <a href="/facts/External_orifice_of_the_uterus/mX2gd3vU">external opening</a>, connecting the cervix with the vagina. The size and shape of the ectocervix and the external opening (external os) can vary according to age, hormonal state, and whether <a href="/facts/Childbirth/KaWFJ4kG">childbirth</a> has taken place. In women who have not had a vaginal delivery, the external opening is small and circular, and in women who have had a vaginal delivery, it is slit-like.<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a> On average, the ectocervix is 3 cm (1.2 in) long and 2.5 cm (1 in) wide.<a class="footnote-ref" id="fnref:23" href="#fn:23"><sup>23</sup></a> </p><p>Blood is supplied to the cervix by the descending branch of the <a href="/facts/Uterine_artery/unEd5Nmn">uterine artery</a><a class="footnote-ref" id="fnref:24" href="#fn:24"><sup>24</sup></a> and drains into the <a href="/facts/Uterine_vein/FNgMp6Qm">uterine vein</a>.<a class="footnote-ref" id="fnref:25" href="#fn:25"><sup>25</sup></a> The <a href="/facts/Pelvic_splanchnic_nerves/myS8z3lz">pelvic splanchnic nerves</a>, emerging as <a href="/facts/Sacral_spinal_nerve_2/MqCkfYT2">S2</a>–<a href="/facts/Sacral_spinal_nerve_3/9gsLH2BQ">S3</a>, transmit the sensation of pain from the cervix to the brain.<a class="footnote-ref" id="fnref:26" href="#fn:26"><sup>26</sup></a> These nerves travel along the <a href="/facts/Uterosacral_ligament/ngkhPuch">uterosacral ligaments</a>, which pass from the uterus to the anterior <a href="/facts/Sacrum/CTFnjSm0">sacrum</a>.<a class="footnote-ref" id="fnref:27" href="#fn:27"><sup>27</sup></a> </p><p>Three channels facilitate <a href="/facts/Lymphatic_system/yw5QLgMT">lymphatic drainage</a> from the cervix.<a class="footnote-ref" id="fnref:28" href="#fn:28"><sup>28</sup></a> The anterior and lateral cervix drains to <a href="/facts/Lymph_node/vkwfcQjH">nodes</a> along the uterine arteries, travelling along the <a href="/facts/Cardinal_ligament/XIub2KLc">cardinal ligaments</a> at the base of the <a href="/facts/Broad_ligament/zXx3ISKo">broad ligament</a> to the <a href="/facts/External_iliac_lymph_nodes/D6UpJrLD">external iliac lymph nodes</a> and ultimately the <a href="/facts/Paraaortic_lymph_node/78KPEcSV">paraaortic lymph nodes</a>. The posterior and lateral cervix drains along the uterine arteries to the <a href="/facts/Internal_iliac_lymph_nodes/QFYIbjem">internal iliac lymph nodes</a> and ultimately the <a href="/facts/Paraaortic_lymph_nodes/78KPEcSV">paraaortic lymph nodes</a>, and the posterior section of the cervix drains to the obturator and presacral <a href="/facts/Lymph_node/vkwfcQjH">lymph nodes</a>.<a class="footnote-ref" id="fnref:29" href="#fn:29"><sup>29</sup></a><a class="footnote-ref" id="fnref:30" href="#fn:30"><sup>30</sup></a><a class="footnote-ref" id="fnref:31" href="#fn:31"><sup>31</sup></a> However, there are variations as lymphatic drainage from the cervix travels to different sets of pelvic nodes in some people. This has implications in scanning nodes for involvement in cervical cancer.<a class="footnote-ref" id="fnref:32" href="#fn:32"><sup>32</sup></a> </p><p>After <a href="/facts/Menstruation/7cv4HzLe">menstruation</a> and directly under the influence of <a href="/facts/Estrogen/dPEewnDV">estrogen</a>, the cervix undergoes a series of changes in position and texture. During most of the menstrual cycle, the cervix remains firm and is positioned low and closed. However, as <a href="/facts/Ovulation/0K3MLdAv">ovulation</a> approaches, the cervix becomes softer and rises to open in response to the higher levels of estrogen present.<a class="footnote-ref" id="fnref:33" href="#fn:33"><sup>33</sup></a> These changes are also accompanied by changes in cervical mucus,<a class="footnote-ref" id="fnref:34" href="#fn:34"><sup>34</sup></a> described below. </p> <h3>Development</h3> <p>As a component of the female <a href="/facts/Human_reproductive_system/wNDMgMDL">reproductive system</a>, the cervix is derived from the two <a href="/facts/Paramesonephric_duct/lF4oBxmP">paramesonephric ducts</a> (also called Müllerian ducts), which develop around the sixth week of <a href="/facts/Human_embryogenesis/JeVmIcT0">embryogenesis</a>. During development, the outer parts of the two ducts fuse, forming a single <a href="/facts/Urogenital/u262MFXg">urogenital</a> canal that will become the <a href="/facts/Vagina/ca5jsTwF">vagina</a>, cervix and <a href="/facts/Uterus/LIrApMXs">uterus</a>.<a class="footnote-ref" id="fnref:35" href="#fn:35"><sup>35</sup></a> The cervix grows in size at a smaller rate than the body of the uterus, so the relative size of the cervix over time decreases, decreasing from being much larger than the body of the uterus in <a href="/facts/Fetus/evocHd0Y">fetal life</a>, twice as large during childhood, and decreasing to its adult size, smaller than the uterus, after puberty.<a class="footnote-ref" id="fnref:36" href="#fn:36"><sup>36</sup></a> Previously, it was thought that during fetal development, the original squamous epithelium of the cervix is derived from the <a href="/facts/Urogenital_sinus/LL7B8Nn9">urogenital sinus</a>, and the original columnar epithelium is derived from the paramesonephric duct. The point at which these two original epithelia meet is called the original squamocolumnar junction.<a class="footnote-ref" id="fnref:37" href="#fn:37"><sup>37</sup></a>: 15–16 New studies show, however, that all the cervical as well as large part of the <a href="/facts/Vaginal_epithelium/xhujU1sT">vaginal epithelium</a> are derived from Müllerian duct tissue and that phenotypic differences might be due to other causes.<a class="footnote-ref" id="fnref:38" href="#fn:38"><sup>38</sup></a> </p> <h3>Histology</h3> <p>The endocervical mucosa is about 3 mm (0.12 in) thick and lined with a single layer of columnar mucous cells. It contains numerous tubular mucous glands, which empty viscous alkaline mucus into the lumen.<a class="footnote-ref" id="fnref:39" href="#fn:39"><sup>39</sup></a> In contrast, the ectocervix is covered with nonkeratinized stratified squamous epithelium,<a class="footnote-ref" id="fnref:40" href="#fn:40"><sup>40</sup></a> which resembles the squamous epithelium lining the vagina.<a class="footnote-ref" id="fnref:41" href="#fn:41"><sup>41</sup></a>: 41 The junction between these two types of epithelia is called the squamocolumnar junction.<a class="footnote-ref" id="fnref:42" href="#fn:42"><sup>42</sup></a>: 408–11 Underlying both types of epithelium is a tough layer of <a href="/facts/Collagen/KsyAb72K">collagen</a>.<a class="footnote-ref" id="fnref:43" href="#fn:43"><sup>43</sup></a> The mucosa of the endocervix is not shed during menstruation. The cervix has more fibrous tissue, including collagen and <a href="/facts/Elastin/9S2w5thw">elastin</a>, than the rest of the uterus.<a class="footnote-ref" id="fnref:44" href="#fn:44"><sup>44</sup></a> </p> <p>In <a href="/facts/Preadolescence/3sImdgGL">prepubertal</a> girls, the functional squamocolumnar junction is just within the cervical canal.<a class="footnote-ref" id="fnref:45" href="#fn:45"><sup>45</sup></a>: 411 Upon entering puberty, due to hormonal influence, and during pregnancy, the columnar epithelium extends outward over the ectocervix as the cervix everts.<a class="footnote-ref" id="fnref:46" href="#fn:46"><sup>46</sup></a>: 106 Hence, this also causes the squamocolumnar junction to move outwards onto the vaginal portion of the cervix, where it is exposed to the acidic vaginal environment.<a class="footnote-ref" id="fnref:47" href="#fn:47"><sup>47</sup></a>: 106 <a class="footnote-ref" id="fnref:48" href="#fn:48"><sup>48</sup></a>: 411 The exposed columnar epithelium can undergo physiological <a href="/facts/Metaplasia/k3S1XCrA">metaplasia</a> and change to tougher metaplastic squamous epithelium in days or weeks,<a class="footnote-ref" id="fnref:49" href="#fn:49"><sup>49</sup></a>: 25 which is very similar to the original squamous epithelium when mature.<a class="footnote-ref" id="fnref:50" href="#fn:50"><sup>50</sup></a>: 411 The new squamocolumnar junction is therefore internal to the original squamocolumnar junction, and the zone of unstable epithelium between the two junctions is called the <i>transformation zone</i> of the cervix.<a class="footnote-ref" id="fnref:51" href="#fn:51"><sup>51</sup></a>: 411 Histologically, the transformation zone is generally defined as surface squamous epithelium with surface columnar epithelium or stromal glands/crypts, or both.<a class="footnote-ref" id="fnref:52" href="#fn:52"><sup>52</sup></a> </p><p>After menopause, the uterine structures involute, and the functional squamocolumnar junction moves into the cervical canal.<a class="footnote-ref" id="fnref:53" href="#fn:53"><sup>53</sup></a>: 41 </p><p><a href="/facts/Nabothian_cyst/rTPyQ61c">Nabothian cysts</a> (or Nabothian follicles) form in the transformation zone where the lining of metaplastic epithelium has replaced mucous epithelium and caused a strangulation of the outlet of some of the mucous glands.<a class="footnote-ref" id="fnref:54" href="#fn:54"><sup>54</sup></a>: 410–411 A buildup of mucus in the glands forms Nabothian cysts, usually less than about 5 mm (0.20 in) in diameter,<a class="footnote-ref" id="fnref:55" href="#fn:55"><sup>55</sup></a> which are considered physiological rather than pathological.<a class="footnote-ref" id="fnref:56" href="#fn:56"><sup>56</sup></a>: 411 Both gland openings and Nabothian cysts are helpful to identify the transformation zone.<a class="footnote-ref" id="fnref:57" href="#fn:57"><sup>57</sup></a>: 106 </p> <h2 id="function">Function</h2> <h3>Fertility</h3> <p>The cervical canal is a pathway through which sperm enter the uterus after being induced by <a href="/facts/Estradiol/eCg3UCgX">estradiol</a> after <a href="/facts/Penile-vaginal_intercourse/okjwpVnB">penile-vaginal intercourse</a>,<a class="footnote-ref" id="fnref:58" href="#fn:58"><sup>58</sup></a> and some forms of <a href="/facts/Artificial_insemination/ccbKoyu4">artificial insemination</a>.<a class="footnote-ref" id="fnref:59" href="#fn:59"><sup>59</sup></a> Some sperm remains in cervical crypts, infoldings of the endocervix, which act as a reservoir, releasing sperm over several hours and maximising the chances of fertilisation.<a class="footnote-ref" id="fnref:60" href="#fn:60"><sup>60</sup></a> A theory states the cervical and uterine contractions during <a href="/facts/Orgasm/Dweqd5oI">orgasm</a> draw semen into the uterus.<a class="footnote-ref" id="fnref:61" href="#fn:61"><sup>61</sup></a> Although the "upsuck theory" has been generally accepted for some years, it has been disputed due to lack of evidence, small sample size, and methodological errors.<a class="footnote-ref" id="fnref:62" href="#fn:62"><sup>62</sup></a><a class="footnote-ref" id="fnref:63" href="#fn:63"><sup>63</sup></a> </p><p>Some methods of <a href="/facts/Fertility_awareness/ugHYtdE9">fertility awareness</a>, such as the <a href="/facts/Creighton_Model_FertilityCare_System/wWq3rVlu">Creighton model</a> and the <a href="/facts/Billings_ovulation_method/fFx9S1hP">Billings method</a> involve estimating a woman's periods of fertility and infertility by observing physiological changes in her body.<a class="footnote-ref" id="fnref:64" href="#fn:64"><sup>64</sup></a> Among these changes are several involving the quality of her cervical mucus: the sensation it causes at the <a href="/facts/Vulva/ECayW89s">vulva</a>, its elasticity (<i><a href="/facts/Spinnbarkeit/7PUw9NRa">Spinnbarkeit</a></i>), its transparency, and the presence of <a href="/facts/Fern_test/fJjeVtKq">ferning</a>.<a class="footnote-ref" id="fnref:65" href="#fn:65"><sup>65</sup></a> </p> <h3>Cervical mucus</h3> <p>Several hundred glands in the endocervix produce 20–60 mg of cervical <a href="/facts/Mucus/hnlBuHAy">mucus</a> a day, increasing to 600 mg around the time of ovulation. It is viscous because it contains large proteins known as <a href="/facts/Mucin/6a0nR12B">mucins</a>. The viscosity and water content vary during the <a href="/facts/Menstrual_cycle/AY6Y9xxM">menstrual cycle</a>; mucus is composed of around 93% water, reaching 98% at midcycle. These changes allow it to function as a barrier or a transport medium to spermatozoa. It contains electrolytes such as calcium, sodium, and potassium; organic components such as glucose, amino acids, and soluble proteins; trace elements including zinc, copper, iron, manganese, and selenium; free fatty acids; enzymes such as <a href="/facts/Amylase/H1MPNNVL">amylase</a>; and <a href="/facts/Prostaglandins/kIKw0gDj">prostaglandins</a>.<a class="footnote-ref" id="fnref:66" href="#fn:66"><sup>66</sup></a> Its consistency is determined by the influence of the hormones estrogen and progesterone. At midcycle, around the time of <a href="/facts/Ovulation/0K3MLdAv">ovulation</a>—a period of high estrogen levels— the mucus is thin and serous to allow sperm to enter the uterus and is more alkaline and, hence, more hospitable to sperm.<a class="footnote-ref" id="fnref:67" href="#fn:67"><sup>67</sup></a> It is also higher in electrolytes, which results in the "ferning" pattern that can be observed in drying mucus under low magnification; as the mucus dries, the salts crystallize, resembling the leaves of a fern.<a class="footnote-ref" id="fnref:68" href="#fn:68"><sup>68</sup></a> The mucus has a stretchy character described as <i>Spinnbarkeit</i> most prominent around ovulation.<a class="footnote-ref" id="fnref:69" href="#fn:69"><sup>69</sup></a> </p><p>At other times in the cycle, the mucus is thick and more acidic due to the effects of progesterone.<a class="footnote-ref" id="fnref:70" href="#fn:70"><sup>70</sup></a> This "infertile" mucus acts as a barrier to keep sperm from entering the uterus.<a class="footnote-ref" id="fnref:71" href="#fn:71"><sup>71</sup></a> Women taking an <a href="/facts/Oral_contraceptive_pill/QfDgVrGA">oral contraceptive pill</a> also have thick mucus from the effects of progesterone.<a class="footnote-ref" id="fnref:72" href="#fn:72"><sup>72</sup></a> Thick mucus also prevents <a href="/facts/Pathogen/axMXtV1M">pathogens</a> from interfering with a nascent pregnancy.<a class="footnote-ref" id="fnref:73" href="#fn:73"><sup>73</sup></a> </p><p>A <a href="/facts/Cervical_mucus_plug/f8px9k7l">cervical mucus plug</a>, called the operculum, forms inside the cervical canal during pregnancy. This provides a protective seal for the uterus against the entry of pathogens and leakage of uterine fluids. The mucus plug is also known to have antibacterial properties. This plug is released as the cervix dilates, either during the first stage of childbirth or shortly before.<a class="footnote-ref" id="fnref:74" href="#fn:74"><sup>74</sup></a> It is visible as a blood-tinged mucous discharge.<a class="footnote-ref" id="fnref:75" href="#fn:75"><sup>75</sup></a> </p> <h3>Childbirth</h3> <p>The cervix plays a major role in <a href="/facts/Childbirth/KaWFJ4kG">childbirth</a>. As the <a href="/facts/Fetus/evocHd0Y">fetus</a> descends within the uterus in preparation for birth, the <a href="/facts/Presentation_(obstetrics)/TEBfevGs">presenting part</a>, usually <a href="/facts/Cephalic_presentation/1Rk0eADl">the head</a>, rests on and is supported by the cervix.<a class="footnote-ref" id="fnref:76" href="#fn:76"><sup>76</sup></a> As labour progresses, the cervix becomes softer and shorter, begins to dilate, and withdraws to face the anterior of the body.<a class="footnote-ref" id="fnref:77" href="#fn:77"><sup>77</sup></a> The support the cervix provides to the fetal head starts to give way when the uterus begins its <a href="/facts/Uterine_contraction/s9C4eRMY">contractions</a>. During childbirth, the <a href="/facts/Cervical_dilation/LavPMzG9">cervix must dilate</a> to a diameter of more than 10 cm (3.9 in) to accommodate the head of the fetus as it descends from the uterus to the vagina. In becoming wider, the cervix also becomes shorter, a phenomenon known as <a href="/facts/Cervical_effacement/ahDHACLX">effacement</a>.<a class="footnote-ref" id="fnref:78" href="#fn:78"><sup>78</sup></a> </p><p>Along with other factors, midwives and doctors use the extent of <a href="/facts/Cervical_dilation/LavPMzG9">cervical dilation</a> to assist decision-making during <a href="/facts/Stages_of_labor/KaWFJ4kG">childbirth</a>.<a class="footnote-ref" id="fnref:79" href="#fn:79"><sup>79</sup></a><a class="footnote-ref" id="fnref:80" href="#fn:80"><sup>80</sup></a> Generally, the active first stage of labour, when the uterine contractions become strong and regular,<a class="footnote-ref" id="fnref:81" href="#fn:81"><sup>81</sup></a> begins when the cervical dilation is more than 3–5 cm (1.2–2.0 in).<a class="footnote-ref" id="fnref:82" href="#fn:82"><sup>82</sup></a><a class="footnote-ref" id="fnref:83" href="#fn:83"><sup>83</sup></a> The second phase of labor begins when the cervix has dilated to 10 cm (4 in), which is regarded as its fullest dilation,<a class="footnote-ref" id="fnref:84" href="#fn:84"><sup>84</sup></a> and is when active pushing and contractions push the baby along the <a href="/facts/Birth_canal/ca5jsTwF">birth canal</a> leading to the birth of the baby.<a class="footnote-ref" id="fnref:85" href="#fn:85"><sup>85</sup></a> <a href="/facts/Parity_(biology)/NU0Vs5uT">The number of past vaginal deliveries</a> is a strong factor in influencing how rapidly the cervix can dilate in labour.<a class="footnote-ref" id="fnref:86" href="#fn:86"><sup>86</sup></a> The time taken for the cervix to dilate and efface is one factor used in reporting systems such as the <a href="/facts/Bishop_score/esR9f5Kv">Bishop score</a>, used to recommend whether interventions such as a <a href="/facts/Forceps_delivery/pEkpxTH9">forceps delivery</a>, <a href="/facts/Labor_induction/NLTR5e2Q">induction</a>, or <a href="/facts/Caesarean_section/GJ623ers">Caesarean section</a> should be used in childbirth.<a class="footnote-ref" id="fnref:87" href="#fn:87"><sup>87</sup></a> </p><p><a href="/facts/Cervical_incompetence/zwRJc9Nt">Cervical incompetence</a> is a condition in which shortening of the cervix due to dilation and thinning occurs before term pregnancy. Short cervical length is the strongest predictor of <a href="/facts/Preterm_birth/szMos8tu">preterm birth</a>.<a class="footnote-ref" id="fnref:88" href="#fn:88"><sup>88</sup></a> </p> <h3>Contraception</h3> <p>Several methods of <a href="/facts/Contraception/qCzhxgH8">contraception</a> involve the cervix. <a href="/facts/Diaphragm_(contraceptive)/P3SCKcPc">Cervical diaphragms</a> are reusable, firm-rimmed plastic devices inserted by a woman before intercourse that cover the cervix. Pressure against the walls of the vagina maintain the position of the diaphragm, and it acts as a physical barrier to prevent the entry of sperm into the uterus, preventing <a href="/facts/Fertilisation/g8u3UKzF">fertilisation</a>. <a href="/facts/Cervical_cap/JaYVh8hP">Cervical caps</a> are a similar method, although they are smaller and adhere to the cervix by suction. Diaphragms and caps are often used in conjunction with <a href="/facts/Spermicide/XjqH3m17">spermicides</a>.<a class="footnote-ref" id="fnref:89" href="#fn:89"><sup>89</sup></a> In one year, 12% of women using the diaphragm will undergo an unintended pregnancy, and with optimal use this falls to 6%.<a class="footnote-ref" id="fnref:90" href="#fn:90"><sup>90</sup></a> Efficacy rates are lower for the cap, with 18% of women undergoing an unintended pregnancy, and 10–13% with optimal use.<a class="footnote-ref" id="fnref:91" href="#fn:91"><sup>91</sup></a> Most types of <a href="/facts/Progestogen-only_pill/o5asNcJT">progestogen-only pills</a> are effective as a contraceptive because they thicken cervical mucus, making it difficult for sperm to pass along the cervical canal.<a class="footnote-ref" id="fnref:92" href="#fn:92"><sup>92</sup></a> In addition, they may also sometimes prevent ovulation.<a class="footnote-ref" id="fnref:93" href="#fn:93"><sup>93</sup></a> In contrast, contraceptive pills that contain both oestrogen and progesterone, the <a href="/facts/Combined_oral_contraceptive_pill/Wudd4dH7">combined oral contraceptive pills</a>, work mainly by preventing <a href="/facts/Ovulation/0K3MLdAv">ovulation</a>.<a class="footnote-ref" id="fnref:94" href="#fn:94"><sup>94</sup></a> They also thicken cervical mucus and thin the lining of the uterus, enhancing their effectiveness.<a class="footnote-ref" id="fnref:95" href="#fn:95"><sup>95</sup></a> </p> <h2 id="clinical-significance">Clinical significance</h2> <h3>Cancer</h3> <p class="note">Main article: <a href="/facts/Cervical_cancer/99vngUyd">Cervical cancer</a></p> <p>In 2008, cervical cancer was the third-most common cancer in women worldwide, with rates varying geographically from less than one to more than 50 cases per 100,000 women.[<i>needs update</i>]<a class="footnote-ref" id="fnref:96" href="#fn:96"><sup>96</sup></a> It is a leading cause of cancer-related death in poor countries, where delayed diagnosis leading to poor outcomes is common.<a class="footnote-ref" id="fnref:97" href="#fn:97"><sup>97</sup></a> The introduction of routine screening has resulted in fewer cases of (and deaths from) cervical cancer, however this has mainly taken place in developed countries. Most developing countries have limited or no screening, and 85% of the global burden occurs there.<a class="footnote-ref" id="fnref:98" href="#fn:98"><sup>98</sup></a> </p><p>Cervical cancer nearly always involves human papillomavirus (HPV) infection.<a class="footnote-ref" id="fnref:99" href="#fn:99"><sup>99</sup></a><a class="footnote-ref" id="fnref:100" href="#fn:100"><sup>100</sup></a> HPV is a virus with numerous strains, several of which predispose to precancerous changes in the cervical epithelium, particularly in the transformation zone, which is the most common area for cervical cancer to start.<a class="footnote-ref" id="fnref:101" href="#fn:101"><sup>101</sup></a> <a href="/facts/HPV_vaccines/S771rmAE">HPV vaccines</a>, such as <a href="/facts/Gardasil/kNjp7s2z">Gardasil</a> and <a href="/facts/Cervarix/kHQ2Q6Jd">Cervarix</a>, reduce the incidence of cervical cancer, by inoculating against the viral strains involved in cancer development.<a class="footnote-ref" id="fnref:102" href="#fn:102"><sup>102</sup></a> </p><p>Potentially precancerous changes in the cervix can be detected by <a href="/facts/Cervical_screening/9NjPS8Ml">cervical screening</a>, using methods including a <a href="/facts/Pap_smear/lsRao90L">Pap smear</a> (also called a cervical smear), in which <a href="/facts/Epithelium/ecKHcHC3">epithelial</a> cells are scraped from the surface of the cervix and <a href="/facts/Cytopathology/za3sn0Jt">examined under a microscope</a>.<a class="footnote-ref" id="fnref:103" href="#fn:103"><sup>103</sup></a> The <a href="/facts/Colposcopy/q9TDDCFI">colposcope</a>, an instrument used to see a magnified view of the cervix, was invented in 1925. The Pap smear was developed by <a href="/facts/Georgios_Papanikolaou/hWnQQxCH">Georgios Papanikolaou</a> in 1928.<a class="footnote-ref" id="fnref:104" href="#fn:104"><sup>104</sup></a> A <a href="/facts/Loop_electrical_excision_procedure/r6L10MhJ">LEEP procedure</a> using a heated loop of <a href="/facts/Platinum/qJC6lQf7">platinum</a> to excise a patch of cervical tissue was developed by <a href="/facts/Aurel_Babes/jHt1sfMf">Aurel Babes</a> in 1927.<a class="footnote-ref" id="fnref:105" href="#fn:105"><sup>105</sup></a> In some parts of the developed world, including the UK, the Pap test has been superseded with <a href="/facts/Liquid-based_cytology/jVhGmFoI">liquid-based cytology</a>.<a class="footnote-ref" id="fnref:106" href="#fn:106"><sup>106</sup></a> </p><p>An inexpensive, cost-effective and practical alternative in poorer countries is <a href="/facts/Cervical_screening/9NjPS8Ml">visual inspection with acetic acid</a> (VIA).<a class="footnote-ref" id="fnref:107" href="#fn:107"><sup>107</sup></a> Instituting and sustaining cytology-based programs in these regions can be difficult, due to the need for trained personnel, equipment and facilities and difficulties in follow-up. With VIA, results and treatment can be available on the same day. As a screening test, VIA is comparable to cervical cytology in accurately identifying precancerous lesions.<a class="footnote-ref" id="fnref:108" href="#fn:108"><sup>108</sup></a> </p><p>A result of <a href="/facts/Dysplasia/sR1UKrbB">dysplasia</a> is usually further investigated, such as by taking a <a href="/facts/Cone_biopsy/bxIJUCE0">cone biopsy</a>, which may also remove the cancerous lesion.<a class="footnote-ref" id="fnref:109" href="#fn:109"><sup>109</sup></a> <a href="/facts/Cervical_intraepithelial_neoplasia/6GoARC51">Cervical intraepithelial neoplasia</a> is a possible result of the biopsy and represents dysplastic changes that may eventually progress to invasive cancer.<a class="footnote-ref" id="fnref:110" href="#fn:110"><sup>110</sup></a> Most cases of cervical cancer are detected in this way, without having caused any symptoms. When symptoms occur, they may include vaginal bleeding, discharge, or discomfort.<a class="footnote-ref" id="fnref:111" href="#fn:111"><sup>111</sup></a> </p> <h3>Inflammation</h3> <p class="note">Main article: <a href="/facts/Cervicitis/sjt9TG64">Cervicitis</a></p> <p>Inflammation of the cervix is referred to as <a href="/facts/Cervicitis/sjt9TG64">cervicitis</a>. This inflammation may be of the endocervix or ectocervix.<a class="footnote-ref" id="fnref:112" href="#fn:112"><sup>112</sup></a> When associated with the endocervix, it is associated with a mucous vaginal discharge and <a href="/facts/Sexually_transmitted_infection/IYL1rxdI">sexually transmitted infections</a> such as <a href="/facts/Chlamydia_infection/bcKTIM1L">chlamydia</a> and <a href="/facts/Gonorrhoea/xulQCkLF">gonorrhoea</a>.<a class="footnote-ref" id="fnref:113" href="#fn:113"><sup>113</sup></a> As many as half of pregnant women having a gonorrheal infection of the cervix are asymptomatic.<a class="footnote-ref" id="fnref:114" href="#fn:114"><sup>114</sup></a> Other causes include overgrowth of the <a href="/facts/Commensal_flora/KnJkboX0">commensal flora</a> of the vagina.<a class="footnote-ref" id="fnref:115" href="#fn:115"><sup>115</sup></a> When associated with the ectocervix, inflammation may be caused by the <a href="/facts/Herpes_simplex/8AQktlTV">herpes simplex</a> virus. Inflammation is often investigated through directly visualising the cervix using a <a href="/facts/Speculum_(medical)/XRvjNg44">speculum</a>, which may appear whiteish due to exudate, and by taking a Pap smear and examining for causal bacteria. Special tests may be used to identify particular bacteria. If the inflammation is due to a bacterium, then antibiotics may be given as treatment.<a class="footnote-ref" id="fnref:116" href="#fn:116"><sup>116</sup></a> </p> <h3>Anatomical abnormalities</h3> <p><a href="/facts/Stenosis_of_uterine_cervix/NyGd6Anv">Cervical stenosis</a> is an abnormally narrow cervical canal, typically associated with trauma caused by removal of tissue for investigation or treatment of cancer, or <a href="/facts/Cervical_cancer/99vngUyd">cervical cancer</a> itself.<a class="footnote-ref" id="fnref:117" href="#fn:117"><sup>117</sup></a><a class="footnote-ref" id="fnref:118" href="#fn:118"><sup>118</sup></a> <a href="/facts/Diethylstilbestrol/0kPqaIex">Diethylstilbestrol</a>, used from 1938 to 1971 to prevent preterm labour and miscarriage, is also strongly associated with the development of cervical stenosis and other abnormalities in the daughters of the exposed women. Other abnormalities include: <a href="/facts/Vaginal_adenosis/s6pXWJDs">vaginal adenosis</a>, in which the squamous epithelium of the ectocervix becomes columnar; cancers such as <a href="/facts/Clear_cell_adenocarcinoma/NmTAg4z8">clear cell adenocarcinomas</a>; cervical ridges and hoods; and development of a cockscomb cervix appearance,<a class="footnote-ref" id="fnref:119" href="#fn:119"><sup>119</sup></a> which is the condition wherein, as the name suggests, the cervix of the <a href="/facts/Uterus/LIrApMXs">uterus</a> is shaped like a <a href="/facts/Comb_(anatomy)/FPnDW1o8">cockscomb</a>. About one-third of women born to <a href="/facts/Diethylstilbestrol/0kPqaIex">diethylstilbestrol</a>-treated mothers (i.e., in-utero exposure) develop a cockscomb cervix.<a class="footnote-ref" id="fnref:120" href="#fn:120"><sup>120</sup></a> </p><p>Enlarged folds or ridges of cervical <a href="/facts/Stroma_(animal_tissue)/hBmBHBSC">stroma</a> (fibrous tissues) and <a href="/facts/Epithelium/ecKHcHC3">epithelium</a> constitute a cockscomb cervix.<a class="footnote-ref" id="fnref:121" href="#fn:121"><sup>121</sup></a> Similarly, cockscomb <a href="/facts/Polyp_(medicine)/BfUMvgSt">polyps</a> lining the cervix are usually considered or grouped into the same overarching description. It is in and of itself considered a <a href="/facts/Benign/Xu5F9mRh">benign</a> abnormality; its presence, however, is usually indicative of DES exposure, and as such, women who experience these abnormalities should be aware of their increased risk of associated pathologies.<a class="footnote-ref" id="fnref:122" href="#fn:122"><sup>122</sup></a><a class="footnote-ref" id="fnref:123" href="#fn:123"><sup>123</sup></a><a class="footnote-ref" id="fnref:124" href="#fn:124"><sup>124</sup></a> </p><p><a href="/facts/Cervical_agenesis/yjaHYuVo">Cervical agenesis</a> is a rare congenital condition in which the cervix completely fails to develop, often associated with the concurrent failure of the vagina to develop.<a class="footnote-ref" id="fnref:125" href="#fn:125"><sup>125</sup></a> Other congenital cervical abnormalities exist, often associated with abnormalities of the vagina and <a href="/facts/Uterus/LIrApMXs">uterus</a>. The cervix may be duplicated in situations such as <a href="/facts/Bicornuate_uterus/jzXHeWTt">bicornuate uterus</a> and <a href="/facts/Uterine_didelphys/poG4n3LQ">uterine didelphys</a>.<a class="footnote-ref" id="fnref:126" href="#fn:126"><sup>126</sup></a> </p><p><a href="/facts/Cervical_polyp/3D5lxcQL">Cervical polyps</a>, which are benign overgrowths of endocervical tissue, if present, may cause bleeding, or a benign overgrowth may be present in the cervical canal.<a class="footnote-ref" id="fnref:127" href="#fn:127"><sup>127</sup></a> <a href="/facts/Cervical_ectropion/k474QITs">Cervical ectropion</a> refers to the horizontal overgrowth of the endocervical columnar lining in a one-cell-thick layer over the ectocervix.<a class="footnote-ref" id="fnref:128" href="#fn:128"><sup>128</sup></a> </p> <h2 id="animals">Animals</h2> <p>Female marsupials have <a href="/facts/Marsupial/zN5s4bMq">paired uteri and cervices</a>.<a class="footnote-ref" id="fnref:129" href="#fn:129"><sup>129</sup></a><a class="footnote-ref" id="fnref:130" href="#fn:130"><sup>130</sup></a> Most <a href="/facts/Eutheria/3fPKIKxx">eutherian</a> (placental) mammal species have a single cervix and a single, bipartite or bicornuate uterus. <a href="/facts/Lagomorph/0J5JT196">Lagomorphs</a>, rodents, aardvarks, and hyraxes have a duplex uterus and two cervices.<a class="footnote-ref" id="fnref:131" href="#fn:131"><sup>131</sup></a> Lagomorphs and rodents share many morphological characteristics and are grouped together in the clade <a href="/facts/Glires/WTlwFWBv">Glires</a>. Anteaters of the family <a href="/facts/Myrmecophagidae/sYa9cRV4">Myrmecophagidae</a> are unusual in that they lack a defined cervix; they are thought to have lost the characteristic rather than other mammals developing a cervix on more than one lineage.<a class="footnote-ref" id="fnref:132" href="#fn:132"><sup>132</sup></a> In <a href="/facts/Domestic_pig/r8rtDBIH">domestic pigs</a>, the cervix contains a series of five interdigitating pads that hold the boar's corkscrew-shaped penis during copulation.<a class="footnote-ref" id="fnref:133" href="#fn:133"><sup>133</sup></a> </p> <h2 id="etymology-and-pronunciation">Etymology and pronunciation</h2> <p>The word <i>cervix</i> (/ˈsɜːrvɪks/) came to English from the <a href="/facts/Latin/pM3Kge85">Latin</a> <i>cervīx</i>, where it means "neck", and like its Germanic counterpart, it can refer not only to the <a href="/facts/Neck/v69tnMYk">neck</a> [of the body] but also to an analogous narrowed part of an object. The cervix uteri (neck of the uterus) is thus the uterine cervix, but in English, the word <i>cervix</i> used alone usually refers to it. Thus the adjective <i>cervical</i> may refer either to the neck (as in <i><a href="/facts/Cervical_vertebrae/M7Kf14h9">cervical vertebrae</a></i> or <i><a href="/facts/Cervical_lymph_nodes/Korh0M99">cervical lymph nodes</a></i>) or to the uterine cervix (as in <i><a href="/facts/Cervical_cap/JaYVh8hP">cervical cap</a></i> or <i><a href="/facts/Cervical_cancer/99vngUyd">cervical cancer</a></i>). </p><p>Latin <i>cervix</i> came from the <a href="/facts/Proto-Indo-European/cVLNoM3p">Proto-Indo-European</a> root <i>ker-</i>, referring to a "structure that projects". Thus, the word cervix is linguistically related to the <a href="/facts/English_language/tpkxGt7b">English</a> word "horn", the <a href="/facts/Persian_language/jfUYbHbt">Persian</a> word for "head" (<a href="/facts/Persian_language/jfUYbHbt">Persian</a>: سر <i>sar</i>), the Greek word for "head" (<a href="/facts/Ancient_Greek_language/LIK7NlUh">Ancient Greek</a>: κορυφή <i>koruphe</i>), and the Welsh and Romanian words for "deer" (<a href="/facts/Welsh_language/4Pz8r6yk">Welsh</a>: <i>carw</i>, Romanian: <i>cerb</i>).<a class="footnote-ref" id="fnref:134" href="#fn:134"><sup>134</sup></a><a class="footnote-ref" id="fnref:135" href="#fn:135"><sup>135</sup></a> </p><p>The cervix was documented in anatomical literature in at least the time of <a href="/facts/Hippocrates/lXUElFQD">Hippocrates</a>; cervical cancer was first described more than 2,000 years ago, with descriptions provided by both <a href="/facts/Hippocrates/lXUElFQD">Hippocrates</a> and <a href="/facts/Aretaeus/YJ0fvC48">Aretaeus</a>.<a class="footnote-ref" id="fnref:136" href="#fn:136"><sup>136</sup></a> However, there was some variation in <a href="/facts/Word_sense/9IR1286V">word sense</a> among early writers, who used the term to refer to both the cervix and the internal uterine orifice.<a class="footnote-ref" id="fnref:137" href="#fn:137"><sup>137</sup></a> The first attested use of the word to refer to the cervix of the uterus was in 1702.<a class="footnote-ref" id="fnref:138" href="#fn:138"><sup>138</sup></a> </p> <h3>Citations</h3> <h3>Cited texts</h3> <ul><li><a href="https://web.archive.org/web/20140426234127/http://publications.nice.org.uk/intrapartum-care-cg55/guidance">"Intrapartum care: Care of healthy women and their babies during childbirth"</a>. <a href="/facts/NICE/83vtP8Lk">NICE</a>. September 2007. Archived from <a href="http://publications.nice.org.uk/intrapartum-care-cg55/guidance">the original</a> on 2014-04-26.</li></ul> <h2 id="external-links">External links</h2> <ul><li> Media related to Cervix uteri at Wikimedia Commons</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Prendiville, Walter; Sankaranarayanan, Rengaswamy (2017), "Anatomy of the uterine cervix and the transformation zone", Colposcopy and Treatment of Cervical Precancer, International Agency for Research on Cancer, retrieved 2024-03-29 <a href="https://www.ncbi.nlm.nih.gov/books/NBK568392/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK568392/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Prendiville, Walter; Sankaranarayanan, Rengaswamy (2017), "Anatomy of the uterine cervix and the transformation zone", Colposcopy and Treatment of Cervical Precancer, International Agency for Research on Cancer, retrieved 2024-03-29 <a href="https://www.ncbi.nlm.nih.gov/books/NBK568392/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK568392/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Prendiville, Walter; Sankaranarayanan, Rengaswamy (2017), "Anatomy of the uterine cervix and the transformation zone", Colposcopy and Treatment of Cervical Precancer, International Agency for Research on Cancer, retrieved 2024-03-29 <a href="https://www.ncbi.nlm.nih.gov/books/NBK568392/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK568392/</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Prendiville, Walter; Sankaranarayanan, Rengaswamy (2017), "Anatomy of the uterine cervix and the transformation zone", Colposcopy and Treatment of Cervical Precancer, International Agency for Research on Cancer, retrieved 2024-03-29 <a href="https://www.ncbi.nlm.nih.gov/books/NBK568392/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK568392/</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Prendiville, Walter; Sankaranarayanan, Rengaswamy (2017), "Anatomy of the uterine cervix and the transformation zone", Colposcopy and Treatment of Cervical Precancer, International Agency for Research on Cancer, retrieved 2024-03-29 <a href="https://www.ncbi.nlm.nih.gov/books/NBK568392/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK568392/</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Prendiville, Walter; Sankaranarayanan, Rengaswamy (2017), "Anatomy of the uterine cervix and the transformation zone", Colposcopy and Treatment of Cervical Precancer, International Agency for Research on Cancer, retrieved 2024-03-29 <a href="https://www.ncbi.nlm.nih.gov/books/NBK568392/" target="_blank">https://www.ncbi.nlm.nih.gov/books/NBK568392/</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"Human Papillomavirus (HPV) Vaccines". National Cancer Institute. Bethesda, MD. 29 December 2011. Retrieved 18 June 2014. <a href="https://www.cancer.gov/cancertopics/factsheet/prevention/HPV-vaccine" target="_blank">https://www.cancer.gov/cancertopics/factsheet/prevention/HPV-vaccine</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Kurman RJ, ed. (1994). Blaustein's Pathology of the Female Genital Tract (4th ed.). New York, NY: Springer New York. pp. 185–201. ISBN 978-1-4757-3889-6. <a href="978-1-4757-3889-6" target="_blank">978-1-4757-3889-6</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Gray H (1995). Williams PL (ed.). Gray's Anatomy (38th ed.). Churchill Livingstone. pp. 1870–73. ISBN 0-443-04560-7. <a href="0-443-04560-7" target="_blank">0-443-04560-7</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Gray H (1995). Williams PL (ed.). Gray's Anatomy (38th ed.). Churchill Livingstone. pp. 1870–73. ISBN 0-443-04560-7. <a href="0-443-04560-7" target="_blank">0-443-04560-7</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Gray H (1995). Williams PL (ed.). Gray's Anatomy (38th ed.). Churchill Livingstone. pp. 1870–73. ISBN 0-443-04560-7. <a href="0-443-04560-7" target="_blank">0-443-04560-7</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Gray H (1995). Williams PL (ed.). Gray's Anatomy (38th ed.). Churchill Livingstone. pp. 1870–73. ISBN 0-443-04560-7. <a href="0-443-04560-7" target="_blank">0-443-04560-7</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Drake RL, Vogl W, Mitchell AW (2005). Gray's Anatomy for Students. Illustrations by Richardson P, Tibbitts R. Philadelphia, PA: Elsevier/Churchill Livingstone. pp. 415, 423. 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