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MeshName = Cervix+uteri |
 
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MeshNumber = A05.360.319.679.256 |
 
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The '''cervix''' (from [[Latin]] "neck") is the lower, narrow portion of the [[uterus]] where it joins with the top end of the [[vagina]]. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall. Approximately half its length is visible with appropriate medical equipment; the remainder lies above the vagina beyond view. It is occasionally called "cervix uteri", or "neck of the uterus".
+
The '''cervix''' (or '''neck of the uterus''') is the lower, narrow portion of the [[uterus]] where it joins with the top end of the [[vagina]]. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall. Approximately half its length is visible with appropriate medical equipment; the remainder lies above the vagina beyond view. It is occasionally called "cervix uteri". Cervix means ''neck'' in Latin.
   
 
== Anatomy ==
 
== Anatomy ==
  +
{{Sex organs}}
 
===Ectocervix===
 
===Ectocervix===
The portion projecting into the vagina is referred to as the ''portio vaginalis'' or ectocervix. On average, the ectocervix is 3 cm long and 2.5 cm wide. It has a convex, elliptical surface and is divided into anterior and posterior lips.
+
The portion projecting into the vagina is referred to as the [[Vaginal portion of cervix|''portio vaginalis'']] or ectocervix. On average, the ectocervix is 3 cm long and 2.5 cm wide. It has a convex, elliptical surface and is divided into anterior and posterior lips.
   
 
====External os====
 
====External os====
Line 38: Line 39:
   
 
=== Cervical crypts ===
 
=== Cervical crypts ===
There are pockets in the lining of the cervix known as ''cervical crypts.'' They function to produce cervical fluid.<ref name ="Weschler">Weschler, Toni, MPH, ''Taking Charge of Your Fertility'', Second Edition, 2002, pg. 59,64</ref>
+
There are pockets in the lining of the cervix known as ''cervical crypts.'' They function to produce cervical fluid.<ref name ="Weschler">Weschler, Toni, MPH, ''Taking Charge of Your Fertility'', Second Edition, 2002, pp. 59, 64.</ref>
  +
  +
   
 
==Histology==
 
==Histology==
The [[epithelium]] of the cervix is nonkeratinized [[stratified squamous epithelium]] at the ectocervix, and [[simple columnar epithelium]] at the cervix proper.<ref>{{BUHistology|19404loa}}</ref><ref>{{USCHistology|rep/c_48}}</ref> At certain times of life, the columnar epithelium is replaced by metaplastic squamous epithelium, and is then known as the transformation zone.
+
The [[epithelium]] of the cervix is varied.
  +
The ectocervix (more distal, by the vagina) is composed of nonkeratinized [[stratified squamous epithelium]]
  +
The endocervix (more proximal, within the uterus) is composed of [[simple columnar epithelium]].<ref>{{BUHistology|19404loa}}</ref>
  +
  +
The area adjacent to the border of the endocervix and ectocervix is known as the 'transformation zone. The Transformation zone undergoes [[metaplasia]] numerous times during normal life. When the endocervix is exposed to the harsh acidic environment of the vagina it undergoes [[metaplasia]] to squamous epithelium which is better suited to the vaginal environment. Similarly when the ectocervix enters the less harsh uterine area it undergoes [[metaplasia]] to become columnar epithelium.
  +
  +
Times in life when this [[metaplasia]] of the transformation zone occurs:
  +
* puberty; when the endocervix everts (moves out) of the uterus
  +
* with the changes of the cervix associated with the normal menstrual cycle
  +
* post-menopause; the uterus shrinks moving the transformation zone upwards
  +
  +
All these changes are normal and the occurrence is said to be [[physiological]].
  +
  +
However all this metaplasia does increase the risk of cancer in this area - the transformation zone is the most common area for cervical cancer to occur.
  +
  +
At certain times of life, the columnar epithelium is replaced by metaplastic squamous epithelium, and is then known as the transformation zone.
   
[[Nabothian cyst]]s are often found in the cervix.
+
[[Nabothian cyst]]s are often found in the cervix.<ref>Weschler, pp. 227–228.</ref>
   
 
==Cervical mucus==
 
==Cervical mucus==
[[Image:Gray34.png |thumb|Mucus plug]]
+
[[Image:Gray34.png|thumb|Mucus plug]]
After a [[Menstrual cycle|menstrual period]] ends, the external os is blocked by [[mucus]] that is thick and acidic. This "infertile" mucus blocks spermatozoa from entering the [[uterus]]. For several days around the time of [[ovulation]], the mucus becomes thin and less acidic ("fertile"), allowing [[Spermatozoon|spermatozoa]] to enter.
+
After a [[Menstrual cycle|menstrual period]] ends, the external os is blocked by [[mucus]] that is thick and acidic. This "infertile" mucus blocks spermatozoa from entering the [[uterus]].<ref>{{cite book |author=Ann Westinore; Evelyn, Dr Billings |title=The Billings Method: Controlling Fertility Without Drugs or Devices |publisher=Life Cycle Books |location=Toronto |year=1998 |pages=37 |isbn=0-919225-17-9}}</ref> For several days around the time of [[ovulation]], "fertile" types of mucus are produced: they have a higher water content, are less acidic, and have a ferning pattern that helps guide [[Spermatozoon|spermatozoa]] through the cervix.<ref name="w59">Weschler, pp. 58–59.</ref> This ferning is a branching pattern seen in the mucus when observed with low magnification.
   
Some methods of [[fertility awareness]] involve estimating a woman's periods of fertility and infertility by observing changes in her body. Among these changes are several involving the quality of her cervical mucus: its amount, its elasticity ([[spinnbarkeit]]), its transparency, and the presence of ''ferning''. This ferning is a branching pattern seen in the mucus when observed with low magnification.
+
Some methods of [[fertility awareness]] involve estimating a woman's periods of fertility and infertility by observing changes in her body. Among these changes are several involving the quality of her cervical mucus: the sensation it causes at the vulva, its elasticity ([[spinnbarkeit]]), its transparency, and the presence of ''ferning''.<ref name="w59" />
   
Most methods of [[hormonal contraception]] work primarily by preventing ovulation, but their effectiveness is increased because they prevent the cervical mucus from thinning. Conversely, methods of thinning the mucus may help to achieve pregnancy. A common method is to take [[guaifenesin]] in the few days before ovulation.
+
[[Image:cervical mucus1.jpg|thumb|left|125px|Cervical mucus]]
  +
Most methods of [[hormonal contraception]] work primarily by preventing ovulation, but their effectiveness is increased because they prevent the fertile types of cervical mucus from being produced. Conversely, methods of thinning the mucus may help to achieve pregnancy. One suggested method is to take [[guaifenesin]] in the few days before ovulation.<ref>Weschler, p. 173.</ref>
   
During pregnancy the cervix is blocked by a special antibacterial mucosal plug which prevents infection, somewhat similar to its state during the infertile portion of the [[menstrual cycle]].<!-- is it the same, or not? --> The mucus plug comes out as the cervix dilates in labor or shortly before..
+
During pregnancy the cervix is blocked by a special antibacterial [[Cervical mucus plug|mucosal plug]] which prevents infection, somewhat similar to its state during the infertile portion of the [[menstrual cycle]].<!-- is it the same, or not? --> The mucus plug comes out as the cervix dilates in labor or shortly before.
   
 
==Cervical position==
 
==Cervical position==
After menstruation and directly under the influence of [[estrogen]], the cervix undergoes a series of changes in position and texture.
+
After menstruation and directly under the influence of [[estrogen]], the cervix undergoes a series of changes in position and texture. During most of the menstrual cycle, the cervix remains firm, like the tip of the nose, and is positioned low and closed. However, as a woman approaches ovulation, the cervix becomes softer, and rises and opens in response to the high levels of estrogen present at ovulation.<ref name="Weschler" /> These changes, accompanied by the production of fertile types of cervical mucus, support the survival and movement of sperm.
* During most of the menstrual cycle, the cervix remains firm, like the tip of the nose, and is positioned low and closed.
 
 
* However, as a woman approaches ovulation, the cervix becomes soft and mushy, and rises and opens in response to the high levels of estrogen present at ovulation.<ref name="Weschler" /> This change, accompanied by the production of fertile-quality cervical mucus, supports the survival and movement of sperm.
 
   
==Functionality==
+
==Function==
During [[menstruation]] the cervix stretches open slightly to allow the [[endometrium]] to be shed. This stretching is believed to be part of the [[cramp]]ing pain that many women experience. Evidence for this is given by the fact that some women's cramps subside or disappear after their first vaginal birth because the cervical opening has widened.
+
During [[menstruation]] the cervix stretches open slightly to allow the [[endometrium]] to be shed. This stretching is believed to be part of the [[cramp]]ing pain that many women experience. Evidence for this is given by the fact that some women's cramps subside or disappear after their first vaginal birth because the cervical opening has widened. During [[childbirth]], contractions of the uterus will [[cervical dilation|dilate the cervix]] up to 10 cm in diameter to allow the child to pass through.
   
During [[childbirth]], contractions of the uterus will [[cervical dilation|dilate the cervix]] up to 10 cm in diameter to allow the fetus to pass through.
+
Stimulation of the cervix leads to orgasm for some women. During [[orgasm]], the cervix convulses and the [[external os]] dilates. Dr. R. Robin Baker and Dr. Mark A. Bellis, both at the [[University of Manchester]], first proposed that this behavior would tend to draw [[semen]] in the [[vagina]] into the [[uterus]], increasing the likelihood of [[Conception (biology)|conception]]. This explanation has been called the "upsuck theory of female orgasm." Komisaruk, Whipple, and Beyer-Flores, in their book, The Science of Orgasm, claimed there is evidence in support of the upsuck theory. Science historian Elisabeth A. Lloyd (The Case of the Female Orgasm) and others have questioned the logic of this theory and the quality of the experimental data used to back it.
   
During [[orgasm]], the cervix convulses and the [[external os]] dilates. Dr. R. Robin Baker and Dr. Mark A. Bellis, both at the [[University of Manchester]], first proposed that this behavior worked in such a way as to draw any [[semen]] in the [[vagina]] into the [[uterus]], increasing the likelihood of [[conception]]. Later researchers, most notably Elisabeth A. Lloyd, have questioned the logic of this theory and the quality of the experimental data used to back it.
+
Short cervix<ref name="pmid9491013">{{cite journal |author=Goldenberg RL, Iams JD, Mercer BM, ''et al'' |title=The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network |journal=Am J Public Health |volume=88 |issue=2 |pages=233–8 |year=1998 |pmid=9491013 |doi=}}</ref> is the strongest predictor of [[preterm birth]].<ref>To MS, Skentou CA, Royston P, Yu CKH, Nicolaides KH. Prediction of patient-specific risk of early preterm delivery using maternal history and sonographic measurement of cervical length: a population-based prospective study. Ultra Obstet Gynecol 2006; 27: 362–367.</ref><ref name = "Fonseca-p462">Fonseca et al. Progesterone and the risk of preterm birth among women with a short cervix. NEJM 2007; vol 357, no 5, pg 462–469.</ref><ref name = "Romero-675">Romero R. Prevention of sponatneous preterm birth: the role of sonographic cervical length in identifying patients who may benefit from progesterone treatment. Ultrasound Obstet Gynecol 2007; 30: 675–686. http://www3.interscience.wiley.com/journal/99020267/home free download</ref> Some treatments to prevent cervical cancer, such as [[Loop electrical excision procedure| LEEP]] may shorten the cervix.
   
 
==Cervical cancer==
 
==Cervical cancer==
In humans the cervix may be affected by [[cervical cancer]], a particular form of [[cancer]] which is detectable by [[cytology|cytological]] study of [[epithelium|epithelial]] [[cell (biology)|cells]] removed from the cervix in a process known as the [[pap smear]]. Evidence now shows that those with exposure to HPV ([[human papilloma virus]]) are at increased risk for cervical cancer. These viruses are related to the viruses that causes [[wart]]s. The incidence of new cases of cervical cancer in the United States was observed to be 7 per 100,000 women in 2004.<ref name ="SEER Cancer Fast Stats">[http://canques.seer.cancer.gov/cgi-bin/cq_submit?dir=delay2004&db=1&rpt=TAB&sel=^12^0^2^0^&dec=4&title=SEER%20Age-Adjusted%20Incidence%20Rate%20Comparison~Delay-Adjusted%20and%20Observed%20Rates~For%20Cervix%20Uteri%20Cancer,%20All%20Races,%20Females,%20All%20Ages~SEER%209%20Registries%20for%201975-2004~Age-Adjusted%20to%20the%202000%20US%20Std%20Population&template=faststats&x=Year%20of%20diagnosis^0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29&y=Statistic%20type^0,2 SEER cancer statistics]</ref>
+
  +
{{main|Cervical cancer}}
  +
  +
[[Human papillomavirus]] (HPV) infection is a necessary factor in the development of nearly all cases of cervical cancer. [[HPV vaccine]]s can reduce the chance of developing cervical cancer, if administered before initiation of sexual activity. Potentially pre-cancerous changes in the cervix can be detected by a [[Pap smear]], in which [[epithelium|epithelial]] [[cell (biology)|cells]] are scraped from the surface of the cervix and [[cytopathology|examined under a microscope]]. With appropriate treatment of detected abnormalities, cervical cancer can be prevented. Most cervical cancers occur in women who have never had a Pap smear, or not had one within the last five years.
  +
  +
Worldwide, cervical cancer is the fifth most deadly cancer in women.<ref name="who fact sheet">{{cite web |author=[[World Health Organization]] |month=February |year=2006 |title=Fact sheet No. 297: Cancer |url=http://www.who.int/mediacentre/factsheets/fs297/en/index.html |accessdate=2007-12-01}}</ref> It affects about 16 per 100,000 women per year and kills about 9 per 100,000 per year.<ref>{{Web cite |title= GLOBOCAN 2002 database: summary table by cancer | url=http://www-dep.iarc.fr/GLOBOCAN/Table1_sel1.htm|accessdate=2008-10-26}}</ref> Pap smear screening has greatly reduced cervical cancer incidence and mortality in nations with regular screening programs.
   
 
==Lymphatic drainage==
 
==Lymphatic drainage==
Line 78: Line 79:
 
Image:Gray1167.svg|Posterior half of uterus and upper part of vagina.
 
Image:Gray1167.svg|Posterior half of uterus and upper part of vagina.
 
</gallery>
 
</gallery>
 
{{Refimprove|date=November 2007}}
 
   
 
==References==
 
==References==
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{{Female reproductive system}}
 
{{Female reproductive system}}
  +
{{Menstrual cycle}}
   
 
[[Category:Female reproductive system]]
 
[[Category:Female reproductive system]]
 
[[Category:Gynecology]]
 
[[Category:Gynecology]]
 
[[Category:Reproductive system]]
 
[[Category:Reproductive system]]
[[Category:Uterus]]
+
   
 
<!--
 
<!--
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[[bg:Маточна шийка]]
 
[[bg:Маточна шийка]]
 
[[cs:Děložní hrdlo]]
 
[[cs:Děložní hrdlo]]
  +
[[cy:Ceg y groth]]
 
[[da:Livmoderhals]]
 
[[da:Livmoderhals]]
 
[[de:Cervix uteri]]
 
[[de:Cervix uteri]]
 
[[es:Cuello uterino]]
 
[[es:Cuello uterino]]
 
[[fr:Col de l'utérus]]
 
[[fr:Col de l'utérus]]
  +
[[it:Cervice]]
 
[[he:צוואר הרחם]]
 
[[he:צוואר הרחם]]
[[ja:子宮頸部]]
 
 
[[lt:Gimdos kaklelis]]
 
[[lt:Gimdos kaklelis]]
 
[[nl:Baarmoederhals]]
 
[[nl:Baarmoederhals]]
  +
[[ja:子宮頸部]]
 
[[no:Livmorhals]]
 
[[no:Livmorhals]]
 
[[pl:Szyjka macicy]]
 
[[pl:Szyjka macicy]]
 
[[pt:Cérvix]]
 
[[pt:Cérvix]]
  +
[[ru:Шейка матки]]
 
[[simple:Cervix]]
 
[[simple:Cervix]]
 
[[sv:Livmoderhals]]
 
[[sv:Livmoderhals]]

Latest revision as of 13:10, January 1, 2009

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Cervix
Schematic frontal view of female anatomy
Latin cervix uteri
Gray's subject #268 1259
System
MeSH A05.360.319.679.256
1: fallopian tube, 2: bladder, 3: pubic bone, 4: g-spot, 5: clitoris, 6: urethra, 7: vagina, 8: ovary, 9: sigmoid colon, 10: uterus, 11: fornix, 12: cervix, 13: rectum, 14: anus

The cervix (or neck of the uterus) is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall. Approximately half its length is visible with appropriate medical equipment; the remainder lies above the vagina beyond view. It is occasionally called "cervix uteri". Cervix means neck in Latin.

Anatomy Edit

EctocervixEdit

The portion projecting into the vagina is referred to as the portio vaginalis or ectocervix. On average, the ectocervix is 3 cm long and 2.5 cm wide. It has a convex, elliptical surface and is divided into anterior and posterior lips.

External osEdit

The ectocervix's opening is called the external os. The size and shape of the external os and the ectocervix varies widely with age, hormonal state, and whether the woman has had a vaginal birth. In women who have not had a vaginal birth the external os appears as a small, circular opening. In women who have had a vaginal birth, the ectocervix appears bulkier and the external os appears wider, more slit-like and gaping.

Endocervical canalEdit

The passageway between the external os and the uterine cavity is referred to as the endocervical canal. It varies widely in length and width, along with the cervix overall. Flattened anterior to posterior, the endocervical canal measures 7 to 8 mm at its widest in reproductive-aged women.

Internal osEdit

The endocervical canal terminates at the internal os which is the opening of the cervix inside the uterine cavity.

Cervical crypts Edit

There are pockets in the lining of the cervix known as cervical crypts. They function to produce cervical fluid.[1]


HistologyEdit

The epithelium of the cervix is varied. The ectocervix (more distal, by the vagina) is composed of nonkeratinized stratified squamous epithelium The endocervix (more proximal, within the uterus) is composed of simple columnar epithelium.[2]

The area adjacent to the border of the endocervix and ectocervix is known as the 'transformation zone. The Transformation zone undergoes metaplasia numerous times during normal life. When the endocervix is exposed to the harsh acidic environment of the vagina it undergoes metaplasia to squamous epithelium which is better suited to the vaginal environment. Similarly when the ectocervix enters the less harsh uterine area it undergoes metaplasia to become columnar epithelium.

Times in life when this metaplasia of the transformation zone occurs:

  • puberty; when the endocervix everts (moves out) of the uterus
  • with the changes of the cervix associated with the normal menstrual cycle
  • post-menopause; the uterus shrinks moving the transformation zone upwards

All these changes are normal and the occurrence is said to be physiological.

However all this metaplasia does increase the risk of cancer in this area - the transformation zone is the most common area for cervical cancer to occur.

At certain times of life, the columnar epithelium is replaced by metaplastic squamous epithelium, and is then known as the transformation zone.

Nabothian cysts are often found in the cervix.[3]

Cervical mucusEdit

Gray34
Mucus plug
Dr Joe KiffAdded by Dr Joe Kiff

After a menstrual period ends, the external os is blocked by mucus that is thick and acidic. This "infertile" mucus blocks spermatozoa from entering the uterus.[4] For several days around the time of ovulation, "fertile" types of mucus are produced: they have a higher water content, are less acidic, and have a ferning pattern that helps guide spermatozoa through the cervix.[5] This ferning is a branching pattern seen in the mucus when observed with low magnification.

Some methods of fertility awareness involve estimating a woman's periods of fertility and infertility by observing changes in her body. Among these changes are several involving the quality of her cervical mucus: the sensation it causes at the vulva, its elasticity (spinnbarkeit), its transparency, and the presence of ferning.[5]

File:Cervical mucus1.jpg
Cervical mucus

Most methods of hormonal contraception work primarily by preventing ovulation, but their effectiveness is increased because they prevent the fertile types of cervical mucus from being produced. Conversely, methods of thinning the mucus may help to achieve pregnancy. One suggested method is to take guaifenesin in the few days before ovulation.[6]

During pregnancy the cervix is blocked by a special antibacterial mucosal plug which prevents infection, somewhat similar to its state during the infertile portion of the menstrual cycle. The mucus plug comes out as the cervix dilates in labor or shortly before.

Cervical positionEdit

After menstruation and directly under the influence of estrogen, the cervix undergoes a series of changes in position and texture. During most of the menstrual cycle, the cervix remains firm, like the tip of the nose, and is positioned low and closed. However, as a woman approaches ovulation, the cervix becomes softer, and rises and opens in response to the high levels of estrogen present at ovulation.[1] These changes, accompanied by the production of fertile types of cervical mucus, support the survival and movement of sperm.

FunctionEdit

During menstruation the cervix stretches open slightly to allow the endometrium to be shed. This stretching is believed to be part of the cramping pain that many women experience. Evidence for this is given by the fact that some women's cramps subside or disappear after their first vaginal birth because the cervical opening has widened. During childbirth, contractions of the uterus will dilate the cervix up to 10 cm in diameter to allow the child to pass through.

Stimulation of the cervix leads to orgasm for some women. During orgasm, the cervix convulses and the external os dilates. Dr. R. Robin Baker and Dr. Mark A. Bellis, both at the University of Manchester, first proposed that this behavior would tend to draw semen in the vagina into the uterus, increasing the likelihood of conception. This explanation has been called the "upsuck theory of female orgasm." Komisaruk, Whipple, and Beyer-Flores, in their book, The Science of Orgasm, claimed there is evidence in support of the upsuck theory. Science historian Elisabeth A. Lloyd (The Case of the Female Orgasm) and others have questioned the logic of this theory and the quality of the experimental data used to back it.

Short cervix[7] is the strongest predictor of preterm birth.[8][9][10] Some treatments to prevent cervical cancer, such as LEEP may shorten the cervix.

Cervical cancerEdit

Main article: Cervical cancer

Human papillomavirus (HPV) infection is a necessary factor in the development of nearly all cases of cervical cancer. HPV vaccines can reduce the chance of developing cervical cancer, if administered before initiation of sexual activity. Potentially pre-cancerous changes in the cervix can be detected by a Pap smear, in which epithelial cells are scraped from the surface of the cervix and examined under a microscope. With appropriate treatment of detected abnormalities, cervical cancer can be prevented. Most cervical cancers occur in women who have never had a Pap smear, or not had one within the last five years.

Worldwide, cervical cancer is the fifth most deadly cancer in women.[11] It affects about 16 per 100,000 women per year and kills about 9 per 100,000 per year.[12] Pap smear screening has greatly reduced cervical cancer incidence and mortality in nations with regular screening programs.

Lymphatic drainageEdit

The lymphatic drainage of the cervix is along the uterine arteries and cardinal ligaments to the parametrial, external iliac vein, internal iliac vein, and obturator and presacral lymph nodes. From these pelvic lymph nodes, drainage then proceeds to the paraaortic lymph nodes. In some women, the lymphatics drain directly to the paraaortic nodes.

Additional imagesEdit

ReferencesEdit

  1. 1.0 1.1 Weschler, Toni, MPH, Taking Charge of Your Fertility, Second Edition, 2002, pp. 59, 64.
  2. Histology at Boston University 19404loa
  3. Weschler, pp. 227–228.
  4. Ann Westinore; Evelyn, Dr Billings (1998). The Billings Method: Controlling Fertility Without Drugs or Devices, 37, Toronto: Life Cycle Books.
  5. 5.0 5.1 Weschler, pp. 58–59.
  6. Weschler, p. 173.
  7. Goldenberg RL, Iams JD, Mercer BM, et al (1998). The preterm prediction study: the value of new vs standard risk factors in predicting early and all spontaneous preterm births. NICHD MFMU Network. Am J Public Health 88 (2): 233–8.
  8. To MS, Skentou CA, Royston P, Yu CKH, Nicolaides KH. Prediction of patient-specific risk of early preterm delivery using maternal history and sonographic measurement of cervical length: a population-based prospective study. Ultra Obstet Gynecol 2006; 27: 362–367.
  9. Fonseca et al. Progesterone and the risk of preterm birth among women with a short cervix. NEJM 2007; vol 357, no 5, pg 462–469.
  10. Romero R. Prevention of sponatneous preterm birth: the role of sonographic cervical length in identifying patients who may benefit from progesterone treatment. Ultrasound Obstet Gynecol 2007; 30: 675–686. http://www3.interscience.wiley.com/journal/99020267/home free download
  11. World Health Organization (2006). Fact sheet No. 297: Cancer. URL accessed on 2007-12-01.
    1. REDIRECT Template:Cite web



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