Editing Uterus

{{short description|Female sex organ in mammals}}
{{hatnote group|
{{redirect|Womb}}
{{redirect|In utero|the album by Nirvana|In Utero{{!}}''In Utero''}}
{{redirect|Uterine|maternal half-siblings|Uterine siblings}}
{{redirect|Intrauterine|the contraceptive devices|Intrauterine device}}
{{Redirect-distinguish|Hystera|Hysteria}}
}}
{{Infobox anatomy
| Name = Uterus
| Latin = uterus
| Greek = ὑστέρα (hystéra)
| Image = Illu_cervix.svg
| Caption = Diagram of human uterus and surrounding structures
| Width = 260
| Precursor = [[Paramesonephric duct]]s
| System = [[Reproductive system]]
| Artery = [[Ovarian artery]] and [[uterine artery]]
| Vein = [[Uterine veins]]
| Nerve =
| Lymph = Body and cervix to [[internal iliac lymph nodes]], fundus to [[para-aortic lymph nodes]], lumbar and superficial inguinal lymph nodes
}}

The '''uterus''' (from [[Latin]] ''uterus'', {{plural form}}: '''uteri''' or '''uteruses''') or '''womb''' ({{IPAc-en|w|uː|m}}) is the [[hollow organ|organ]] in the [[reproductive system]] of most [[female]] [[mammal]]s, including humans, that accommodates the [[embryonic development|embryonic]] and [[prenatal development|fetal development]] of one or more [[Fertilized egg|fertilized eggs]] until [[birth]].<ref>{{Cite book |last=Linzey |first=Donald W. |url=https://books.google.com/books?id=Rur4DwAAQBAJ&pg=PA306 |title=Vertebrate Biology: Systematics, Taxonomy, Natural History, and Conservation |date=2020-08-04 |publisher=JHU Press |isbn=978-1-4214-3733-0 |language=en}}</ref> The uterus is a [[hormone]]-responsive [[sex organ]] that contains [[uterine gland|glands]] in its [[endometrium|lining]] that secrete [[uterine milk]] for embryonic nourishment. (The term ''uterus'' is also applied to analogous structures in some non-mammalian animals.)

In the human, the lower end of the uterus is a narrow part known as the [[Uterine isthmus|isthmus]] that connects to the [[cervix]], the anterior gateway leading to the [[vagina]]. The upper end, the body of the uterus, is connected to the [[fallopian tubes]] at the [[uterine horns]]; the rounded part, the fundus, is above the openings to the fallopian tubes. The connection of the [[uterine cavity]] with a fallopian tube is called the [[uterotubal junction]]. The [[zygote|fertilized egg]] is carried to the uterus along the fallopian tube. It will have [[Cleavage (embryo)|divided]] on its journey to form a [[blastocyst]] that will [[Implantation (embryology)|implant]] itself into the lining of the uterus – the [[endometrium]], where it will receive nutrients and develop into the [[embryo]] proper, and later [[fetus]], for the duration of the [[pregnancy]].

In the [[human embryonic development|human embryo]], the uterus develops from the [[paramesonephric duct]]s, which fuse into the single organ known as a simplex uterus. The uterus has different forms in many other animals and in some it exists as two separate uteri known as a duplex uterus.

In [[medicine]] and related professions, the term ''uterus'' is consistently used, while the [[Germanic languages|Germanic]]-derived term ''[[wikt:womb|womb]]'' is commonly used in everyday contexts. Events occurring within the uterus are described with the term '''''in utero'''''.

== Structure ==
[[File:3D Medical Animation Uterus.jpg|alt=Different regions of the uterus displayed and labelled using a 3D medical animation still shot|thumb|261x261px|Different regions of the uterus, and the [[vagina]], displayed and labelled using a 3D medical illustration]]

In humans, the uterus is located within the [[pelvis|pelvic region]] immediately behind and almost overlying the [[urinary bladder|bladder]], and in front of the [[sigmoid colon]]. The human uterus is pear-shaped and about {{Convert|7.6|cm|in|abbr=on}} long, {{Convert|4.5|cm|in|abbr=on}} broad (side to side), and {{Convert|3.0|cm|in|abbr=on}} thick.<ref name="Manual of Obstetrics">Manual of Obstetrics. (3rd ed.). Elsevier 2011. pp. 1–16. {{ISBN|9788131225561}}.</ref><ref>{{Cite book|title=Health & physical assessment in nursing|last=Donita|first=D'Amico|publisher=Pearson|others=Barbarito, Colleen|year=2015|isbn=9780133876406|edition=3rd |location=Boston|pages=645|oclc=894626609}}</ref> A typical adult uterus weighs about 60 grams. The uterus can be divided anatomically into four regions: the '''fundus''' – the uppermost rounded portion of the uterus above the openings of the [[fallopian tube]]s,<ref name="openstax">{{cite web |title=27.2 Anatomy and Physiology of the Female Reproductive System - Anatomy and Physiology {{!}} OpenStax |url=https://openstax.org/books/anatomy-and-physiology/pages/27-2-anatomy-and-physiology-of-the-female-reproductive-system#fig-ch28_02_06 |website=openstax.org |date=25 April 2013 |access-date=4 November 2022 |language=en}}</ref> the '''body''', the [[cervix]], and the [[cervical canal]]. The cervix protrudes into the [[vagina]]. The uterus is held in position within the pelvis by [[ligaments]], which are part of the [[endopelvic fascia]]. These ligaments include the [[pubocervical ligaments]], the [[cardinal ligament]]s, and the [[uterosacral ligament]]s. It is covered by a sheet-like fold of peritoneum, the [[broad ligament]].<ref>Gray's Anatomy for Students, 2nd edition</ref>

===Layers===
{|class="wikitable" align="right" style="margin-left:10px;"
|+ Uterine wall thickness (cm)<ref>{{cite book|author1=Nandita Palshetkar|author2=Rishma Dhillon Pai|author3=Hrishikesh D Pai|title=Textbook of Hysteroscopy|url=https://books.google.com/books?id=WW9bQtmpR3sC&pg=PA135|date=2012-09-30|publisher=JP Medical Ltd|isbn=978-93-5025-781-4|pages=135–}}</ref>
|-
! Location !! Mean (mm) !! Range (mm)
|-
| Anterior wall || 23 || 17 - 25
|-
| Posterior wall || 21 || 15 - 25
|-
| Fundus || 20 || 15 - 22
|-
| Isthmus || 10 || 8 - 22
|}

[[File:Gray1169.png|thumb|Vertical section of mucous membrane of human uterus]]
The uterus has three layers, which together form the '''uterine wall'''. From innermost to outermost, these layers are the [[endometrium]], [[myometrium]], and [[perimetrium]].<ref name="T and D">{{cite book |last1=Tortora |first1=G |last2=Derrickson |first2=B |title=Principles of anatomy & physiology. |date=2011 |publisher=Wiley |isbn=9780470646083 |page=1105 |edition=13th.}}</ref>

The endometrium is the inner [[Epithelium|epithelial layer]], along with its [[mucous membrane]], of the [[mammal]]ian uterus. It has a basal layer and a functional layer; the functional layer thickens and then is shed during the [[menstrual cycle]] or [[estrous cycle]]. During [[pregnancy]], the [[uterine gland]]s and [[blood vessel]]s in the endometrium further increase in size and number and form the [[decidua]]. Vascular spaces fuse and become interconnected, forming the [[placenta]], which supplies [[oxygen]] and nutrition to the [[embryo]] and [[fetus]].<ref name=histology>[http://www.lab.anhb.uwa.edu.au/mb140/CorePages/FemaleRepro/FemaleRepro.htm Blue Histology - Female Reproductive System] {{webarchive|url=https://web.archive.org/web/20070221174122/http://www.lab.anhb.uwa.edu.au/mb140/CorePages/FemaleRepro/FemaleRepro.htm |date=2007-02-21 }}. School of Anatomy and Human Biology&nbsp;— The University of Western Australia Accessed 20061228 20:35</ref><ref name=Guyton2006>{{cite book | title =Textbook of Medical Physiology | chapter = Chapter 81 Female Physiology Before Pregnancy and Female Hormones | pages = 1018ff | edition = 11th |veditors = Guyton AC, Hall JE | publisher = Elsevier Saunders | year = 2006 | isbn = 9780721602400}}</ref>

The myometrium of the uterus mostly consists of [[smooth muscle]]. The innermost layer of myometrium is known as the '''junctional zone''', which becomes thickened in [[adenomyosis]].<ref>{{Cite web|url=https://www.cancer.gov/publications/dictionaries/cancer-terms|title=NCI Dictionary of Cancer Terms|website=National Cancer Institute|access-date=2017-12-27|url-status=live|archive-url=https://web.archive.org/web/20171226183201/https://www.cancer.gov/publications/dictionaries/cancer-terms|archive-date=2017-12-26}}</ref>

The perimetrium is a [[serous membrane|serous]] layer of visceral [[peritoneum]]. It covers the outer surface of the uterus.<ref>{{cite book |last1=Ross |first1=Michael H. |last2=Pawlina |first2=Wojciech|edition=Sixth |title=Histology, a text and atlas|page=848}}</ref>

Surrounding the uterus is a layer or band of fibrous and fatty connective tissue called the [[parametrium]] that connects the uterus to other tissues of the pelvis.

[[Commensalism|Commensal]] and [[Mutualism (biology)|mutualistic]] organisms are present in the uterus and form the [[uterine microbiome]].<ref name="FranasiakScott2015">{{cite journal|last1=Franasiak|first1=Jason M.|last2=Scott|first2=Richard T.|title=Reproductive tract microbiome in assisted reproductive technologies|journal=Fertility and Sterility|volume=104|issue=6|year=2015|pages=1364–1371|issn=0015-0282|doi=10.1016/j.fertnstert.2015.10.012|pmid=26597628 |doi-access=free}}</ref><ref name="Verstrael6">{{cite journal|last1=Verstraelen|first1=Hans|last2=Vilchez-Vargas|first2=Ramiro|last3=Desimpel|first3=Fabian|last4=Jauregui|first4=Ruy|last5=Vankeirsbilck|first5=Nele|last6=Weyers|first6=Steven|last7=Verhelst|first7=Rita|last8=De Sutter|first8=Petra|last9=Pieper|first9=Dietmar H.|last10=Van De Wiele|first10=Tom|title=Characterisation of the human uterine microbiome in non-pregnant women through deep sequencing of the V1-2 region of the 16S rRNA gene|journal=PeerJ|volume=4|year=2016|pages=e1602|issn=2167-8359|doi=10.7717/peerj.1602|pmid=26823997|pmc=4730988 |doi-access=free }}</ref><ref name="MorKwon2015">{{cite journal|last1=Mor|first1=Gil|last2=Kwon|first2=Ja-Young|title=Trophoblast-microbiome interaction: a new paradigm on immune regulation|journal=American Journal of Obstetrics and Gynecology|volume=213|issue=4|year=2015|pages=S131–S137|issn=0002-9378|doi=10.1016/j.ajog.2015.06.039| pmid=26428492|pmc=6800181}}</ref><ref name="PayneBayatibojakhi2014">{{cite journal|last1=Payne|first1=Matthew S.|last2=Bayatibojakhi|first2=Sara|title=Exploring Preterm Birth as a Polymicrobial Disease: An Overview of the Uterine Microbiome|journal=Frontiers in Immunology|volume=5|year=2014|issn=1664-3224|doi=10.3389/fimmu.2014.00595|pmid=25505898|pmc=4245917|pages=595|doi-access=free}}</ref>

=== Support ===
[[File:Gray1161.png|thumb|right|220px|Uterus covered by the broad ligament]]
The uterus is primarily supported by the [[pelvic diaphragm]], [[perineal body]], and [[urogenital diaphragm]]. Secondarily, it is supported by ligaments, including the [[peritoneal ligament]] and the [[broad ligament of uterus]].<ref name=ucc>[http://www.ucc.ie/medsoc/1styr/resources/anatomy/The%20Pelvis.doc The Pelvis] University College Cork Archived from [https://web.archive.org/web/20080227041631/http://www.ucc.ie/medsoc/1styr/resources/anatomy/The%20Pelvis.doc the original] on 2008-02-27</ref>

==== Major ligaments ==== <!--Major ligaments of uterus redirects here-->
The uterus is held in place by several peritoneal ligaments, of which the following are the most important (there are two of each):

{| class="wikitable"
! Name !! From !! To
|-
| [[Uterosacral ligaments]] || Posterior cervix  || Anterior face of [[sacrum]]
|-
| [[Cardinal ligaments]] || Side of the cervix || [[Ischial spine]]s
|-
| [[Pubocervical ligaments]]<ref name=ucc/> ||Side of the cervix||[[Pubic symphysis]]
|}

=== Axis ===
Normally, the human uterus lies in anteversion and anteflexion. In most women, the long axis of the uterus is bent forward on the long axis of the vagina, against the urinary bladder. This position is referred to as anteversion of the uterus. Furthermore, the long axis of the body of the uterus is bent forward at the level of the internal os with the long axis of the cervix. This position is termed anteflexion of the uterus.<ref>Snell, Clinical Anatomy by regions, 8th edition</ref> The uterus assumes an anteverted position in 50% of women, a retroverted position in 25% of women, and a midposed position in the remaining 25% of women.<ref name="Manual of Obstetrics" />

=== Position ===
[[File:Figure 28 02 01.JPG|thumb|Uterus shown in position in the body]]

The uterus is located in the middle of the pelvic cavity, in the [[frontal plane]] (due to the [[broad ligament of the uterus]]). The fundus does not extend above the ''[[linea terminalis]]'', while the vaginal part of the cervix does not extend below the [[interspinal line]]. The uterus is mobile and moves posteriorly under the pressure of a full bladder, or anteriorly under the pressure of a full rectum. If both are full, it moves upwards. Increased intra-abdominal pressure pushes it downwards. The mobility is conferred to it by a musculo-fibrous apparatus that consists of suspensory and sustentacular parts. Under normal circumstances, the suspensory part keeps the uterus in anteflexion and anteversion (in 90% of women) and keeps it "floating" in the pelvis. The meanings of these terms are described below:
[[File:Uterus image-Photoroom.png|thumb|Top-down view of the uterus and other pelvic organs, here depicted as they are usually positioned inside the body<ref>{{Cite book |last=Bohannon |first=Cat |title=[[Eve: How the Female Body Drove 200 Million Years of Human Evolution]] |date=October 3, 2024 |publisher=[[Penguin Random House]] |isbn=978-0385350549 |pages=76 |quote=Female pelvic anatomy: it's a tight fit.}}</ref>]]
{| class="wikitable"
! Distinction !! More common !! Less common
|-
| Position tipped || "Anteverted": Tipped forward || "[[Retroverted uterus|Retroverted]]": Tipped backwards
|-
| Position of fundus || "Anteflexed": Fundus is pointing forward relative to the cervix || "Retroflexed": Fundus is pointing backward
|}
[[File:Positions of the human uterus 1.png|thumb|1. Anteversion with slight anteflexion<br>
2. Anteversion with marked anteflexion<br>
3. Anteversion with retrocession<br>
4. Retroversion<br>
5. Retroversion with retroflexion|left]]
The sustentacular part supports the pelvic organs and comprises the larger [[pelvic diaphragm]] in the back and the smaller [[urogenital diaphragm]] in the front.

The pathological changes of the position of the uterus are:
* [[Retroverted uterus|retroversion]]/retroflexion, if it is fixed
* hyperanteflexion&nbsp;– tipped too forward; most commonly congenital, but may be caused by tumors
* anteposition, retroposition, lateroposition&nbsp;– the whole uterus is moved; caused by [[parametritis]] or tumors
* elevation, descensus, [[Uterine prolapse|prolapse]]
* rotation (the whole uterus rotates around its longitudinal axis), torsion (only the body of the uterus rotates around)
* inversion

In cases where the uterus is "tipped", also known as [[retroverted uterus]], the woman may have symptoms of pain during sexual intercourse, pelvic pain during menstruation, minor incontinence, urinary tract infections, fertility difficulties,<ref>{{cite web |url=http://www.womens-health.co.uk/retrover.asp |title=Retroverted Uterus: What it is & How it Affects Pregnancy |website=www.womens-health.co.uk |url-status=live |archive-url=https://web.archive.org/web/20131005022310/http://www.womens-health.co.uk/retrover.asp |archive-date=2013-10-05}}</ref> and difficulty using tampons. A pelvic examination by a doctor can determine if a uterus is tipped.<ref>[http://www.americanpregnancy.org/womenshealth/tippeduterus.html Tipped Uterus:Tilted Uterus] {{webarchive |url=https://web.archive.org/web/20110224161243/http://www.americanpregnancy.org/womenshealth/tippeduterus.html |date=2011-02-24 }} AmericanPregnancy.org. Accessed 25 March 2011</ref>

=== Blood, lymph, and nerve supply ===
[[File:Uterine arterial vasculature.svg|thumb|150px|Diagram of uterine blood supply]]
The human uterus is supplied by arterial blood both from the [[uterine artery]] and the [[ovarian artery]]. Another anastomotic branch may also supply the uterus from anastomosis of these two arteries.

Afferent nerves supplying the uterus are [[Spinal nerves#Thoracic nerves|T11 and T12]]. Sympathetic supply is from the [[Superior hypogastric plexus|hypogastric plexus]] and the [[ovarian plexus]]. Parasympathetic supply is from the S2, S3 and S4 nerves.

== Development ==
{{Main|Development of the reproductive system}}
[[File:The uterus differentiates from the fetal Müllerian ducts..jpg|thumb|left|Differentiation of uterus]]
Bilateral [[Müllerian duct]]s form during early human fetal life. In males, [[anti-Müllerian hormone]] (AMH) secreted from the testes leads to the ducts' regression. In females, these ducts give rise to the [[fallopian tubes]] and the uterus. In humans, the lower segments of the two ducts fuse to form a single uterus; in cases of [[uterine malformation]]s this fusion may be disturbed. The different uterine morphologies among the mammals are due to varying degrees of fusion of the Müllerian ducts.

Various congenital conditions of the uterus can develop ''in utero''. Though uncommon, some of these are [[didelphic uterus]], [[bicornate uterus]] and others.<ref>{{Cite web |url=http://www.glowm.com/section_view/heading/Surgical%20Correction%20of%20Uterovaginal%20Anomalies/item/48 |title=Surgical Correction of Uterovaginal Anomalies {{!}} GLOWM |website=www.glowm.com |language=en |access-date=2017-12-27 |url-status=live |archive-url=https://web.archive.org/web/20171228112310/http://www.glowm.com/section_view/heading/Surgical%20Correction%20of%20Uterovaginal%20Anomalies/item/48 |archive-date=2017-12-28}}</ref>

See also [[List of related male and female reproductive organs]].
{{Clear}}

== Function ==
[[File:Human female inner genitalia.png|thumb|Maximum penetration depth of the penis]]
The primary reproductive function of the human uterus is to prepare for the implantation of a [[zygote]], a fertilized [[Egg cell|ovum]], and maintenance of pregnancy if implantation occurs.<ref name="Critchley-2020">{{Cite journal |last1=Critchley |first1=Hilary O. D. |last2=Maybin |first2=Jacqueline A. |last3=Armstrong |first3=Gregory M. |last4=Williams |first4=Alistair R. W. |date=2020-07-01 |title=Physiology of the Endometrium and Regulation of Menstruation |journal=Physiological Reviews |language=en |volume=100 |issue=3 |pages=1149–1179 |doi=10.1152/physrev.00031.2019 |pmid=32031903 |s2cid=211063583 |issn=0031-9333|doi-access=free |hdl=20.500.11820/36236a4e-a35e-4818-abe3-5d8b278c66f8 |hdl-access=free }}</ref> Traveling along the [[fallopian tube]] on its way to the uterine cavity, the zygote divides [[mitosis|mitotically]] to become a [[blastocyst]], which ultimately attaches to the uterine wall and  [[Implantation (embryology)|implants]] into the [[endometrium]].<ref name="openstax" /> The [[placenta]] later develops to nourish the embryo, which grows through [[human embryonic development|embryonic]] and [[prenatal development|fetal development]] until [[childbirth]]. During this process, the uterus grows to accommodate the growing fetus.<ref name="Ameer-2023">{{Citation |last1=Ameer |first1=Muhammad Atif |title=Anatomy, Abdomen and Pelvis: Uterus |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK470297/ |work=StatPearls |access-date=2023-10-30 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29262069 |last2=Fagan |first2=Sarah E. |last3=Sosa-Stanley |first3=Jessica N. |last4=Peterson |first4=Diana C.}}</ref> When normal labor begins, the uterus forcefully contracts as the cervix dilates, which results in delivery of the infant.<ref name="Ameer-2023" />

In the absence of pregnancy, [[menstruation]] occurs.<ref name="Critchley-2020" /> The withdrawal of female sex hormones, [[estrogen]] and [[progesterone]], which occurs in the absence of fertilization, triggers the shedding of the functional layer of the endometrium.<ref name="Critchley-2020" /> This layer is broken down, shed, and restored in anticipation of the next menstrual cycle.<ref name="Critchley-2020" /> The average bleeding duration during menses is 5-7 days after which the menstrual cycle begins again.<ref>{{Citation |last1=Thiyagarajan |first1=Dhanalakshmi K. |title=Physiology, Menstrual Cycle |date=2023 |url=http://www.ncbi.nlm.nih.gov/books/NBK500020/ |work=StatPearls |access-date=2023-10-30 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=29763196 |last2=Basit |first2=Hajira |last3=Jeanmonod |first3=Rebecca}}</ref>

== Clinical significance ==
During [[pregnancy]], the growth rate of the fetus can be assessed by measuring the [[fundal height]].

{{anchor|Fluid accumulation}}
Some [[pathology|pathological]] states include:
 
[[File:Endometrial fluid accumulation, postmenopausal.jpg|thumb|[[Transvaginal ultrasonography]] showing a uterine fluid accumulation in a [[postmenopausal]] woman]]
* Accumulation of fluids other than blood or of unknown constitution. One study came to the conclusion that [[postmenopausal]] women with endometrial fluid collection on [[gynecologic ultrasonography]] should undergo [[endometrial biopsy]] if the endometrial lining is thicker than 3&nbsp;mm or if the endometrial fluid is [[echogenic]]. In cases of a lining 3&nbsp;mm or less and clear endometrial fluid, endometrial biopsy was not regarded to be necessary, but [[endocervical curettage]] to rule out endocervical cancer was recommended.<ref>{{cite journal |vauthors=Takacs P, De Santis T, Nicholas MC, Verma U, Strassberg R, Duthely L |title=Echogenic endometrial fluid collection in postmenopausal women is a significant risk factor for disease |journal=J Ultrasound Med |volume=24 |issue=11 |pages=1477–81 |date=November 2005 |pmid=16239648 |doi= 10.7863/jum.2005.24.11.1477|s2cid=20258522 |doi-access= }}</ref>
* [[Hematometra]], which is accumulation of blood within the uterus.<ref>{{Cite news|url=https://www.merckmanuals.com/home/women-s-health-issues/noncancerous-gynecologic-abnormalities/cervical-stenosis|title=Cervical Stenosis - Women's Health Issues - Merck Manuals Consumer Version|work=Merck Manuals Consumer Version|access-date=2018-11-07|language=en-US|archive-date=2018-11-08|archive-url=https://web.archive.org/web/20181108025827/https://www.merckmanuals.com/home/women-s-health-issues/noncancerous-gynecologic-abnormalities/cervical-stenosis|url-status=live}}</ref>
* [[Uterine prolapse|Prolapse of the uterus]]
* [[Carcinoma of the cervix]]&nbsp;– malignant neoplasm
* [[Carcinoma of the uterus]]&nbsp;– malignant neoplasm
* [[Uterine fibroids|Fibroid]]s&nbsp;– benign neoplasms
* [[Adenomyosis]]&nbsp;– ectopic growth of endometrial tissue within the myometrium
* [[Endometritis]], infection at the uterine cavity
* [[Pyometra]]&nbsp;– infection of the uterus, most commonly seen in dogs
* [[Asherman's syndrome]], also known as intrauterine [[adhesions]], occurs when the basal layer of the endometrium is damaged by instrumentation (e.g., [[Dilation and curettage|D&C]]) or infection (e.g., endometrial [[tuberculosis]]) resulting in endometrial scarring followed by adhesion formation that partially or completely obliterates the uterine cavity
* Myometritis – inflammation of the muscular uterine wall.<ref>{{cite web|title=Myometritis - Medical Definition from MediLexicon|url=http://www.medilexicon.com/dictionary/58501|website=www.medilexicon.com|url-status=live|archive-url=https://web.archive.org/web/20161229101813/http://www.medilexicon.com/dictionary/58501|archive-date=2016-12-29}}</ref>

===Malformations===
[[File:Uterine_malformation.jpg|thumb|Four types of [[uterine malformation]]]]
[[Uterine malformation]]s are mainly [[birth defect|congenital malformations]], and include ''[[uterus didelphys]]'', [[bicornuate uterus]] and [[septate uterus]]. Congenital absence of the uterus is known as [[Müllerian agenesis]].

===Surgery===
A [[hysterectomy]] is the surgical removal of the uterus, which may be carried out for a number of reasons including the ridding of [[neoplasm|tumours]] both benign and [[cancer|malignant]]. A complete hysterectomy involves the removal of the body, fundus, and cervix of the uterus. A partial hysterectomy may just involve the removal of the uterine body while leaving the cervix intact. It is the most commonly performed [[gynecological surgery|gynecological surgical procedure]].

===Transplants===
[[Uterus transplantation]]s have been successfully carried out in a number of countries. The transplant is intended to be temporary – recipients will have to undergo a [[hysterectomy]] after one or two successful pregnancies. This is done to avoid the need to take [[immunosuppressive drug]]s for life with a consequent increased risk of infection.<ref>{{cite web | url=http://www.popsci.com/blog-network/ladybits/everything-you-need-know-about-uterus-transplants | title=Everything You Need To Know About Uterus Transplants | work=Popular Science | date=18 February 2014 | access-date=10 October 2014 | author=Ossola, Alexandra}}</ref>

The procedure remains the last resort: it is as of 2023, a relatively new and somewhat experimental procedure, performed only by certain specialist surgeons in select centres, it is expensive and unlikely to be covered by insurance, and it involves risk of infection and organ rejection. Some [[ethics]] specialists consider the risks to a live donor too great, and some find the entire procedure ethically questionable, especially since the transplant is not a life-saving procedure.<ref>{{cite news|url=http://www.pjstar.com/article/20141003/NEWS/141009710/?Start=2|title=Medical first: Baby born to woman who got new womb|work=[[Journal Star (Peoria)|Journal Star]]|publisher=2006-2014 Gatehouse Media, Inc.|date=4 October 2014|access-date=4 October 2014}}</ref><ref>{{cite news|url=https://www.bbc.co.uk/news/health-29485996|title=BBC News|date=4 October 2014|access-date=5 October 2014}}</ref><ref>{{cite web|url=https://www.telegraph.co.uk/health/healthnews/11139991/The-first-baby-has-been-born-following-a-womb-transplant.html|archive-url=https://web.archive.org/web/20141004025236/http://www.telegraph.co.uk/health/healthnews/11139991/The-first-baby-has-been-born-following-a-womb-transplant.html|url-status=dead|archive-date=4 October 2014|title=The Daily Telegraph|date=3 October 2014|work=Telegraph.co.uk|access-date=5 October 2014}}</ref>

==Other animals==
Most animals that lay [[egg (biology)|eggs]], such as [[bird]]s and [[reptile]]s, including most [[ovoviviparity|ovoviviparous]] species, have an [[oviduct]] instead of a uterus. However,  recent research into the biology of the [[Viviparity|viviparous]] (not merely [[ovoviviparity|ovoviviparous]]) [[skink]] ''[[Trachylepis]] ivensi'' has revealed development of a very close analogue to [[eutheria]]n mammalian placental development.<ref>{{cite journal | last1 = Blackburn | first1 = D. G. | last2 = Flemming | first2 = A. F. | year = 2011 | title = Invasive implantation and intimate placental associations in a placentotrophic African lizard, Trachylepis ivensi (scincidae) | journal = Journal of Morphology | volume = 273| issue = 2| pages = 137–59| doi = 10.1002/jmor.11011 | pmid=21956253| s2cid = 5191828 }}</ref>

In [[monotreme]]s, mammals which lay eggs, namely the [[platypus]] and the [[echidna]]s, either the term ''uterus'' or ''oviduct'' is used to describe the same organ, but the egg does not develop a [[placenta]] within the mother and thus does not receive further nourishment after formation and [[fertilization]].

[[Marsupials]] have two uteri, each of which connect to a lateral vagina and both use a third, middle "vagina", which functions as the birth canal.<ref name="Tyndale-BiscoeRenfree1987">{{cite book|author1=Hugh Tyndale-Biscoe|author2=Marilyn Renfree|title=Reproductive Physiology of Marsupials|url=https://books.google.com/books?id=HpjovN0vXW4C&q=uterus+OR+uteri|date=30 January 1987|publisher=Cambridge University Press|isbn=978-0-521-33792-2|access-date=19 October 2020|archive-date=10 April 2021|archive-url=https://web.archive.org/web/20210410061838/https://books.google.com/books?id=HpjovN0vXW4C&q=uterus+OR+uteri|url-status=live}}</ref><ref name="Nowak1999">{{cite book|author=Ronald M. Nowak|title=Walker's Mammals of the World|url=https://books.google.com/books?id=T37sFCl43E8C&q=uterus|date=7 April 1999|publisher=JHU Press|isbn=978-0-8018-5789-8|access-date=4 September 2017|archive-date=10 April 2021|archive-url=https://web.archive.org/web/20210410044549/https://books.google.com/books?id=T37sFCl43E8C&q=uterus|url-status=live}}</ref> Marsupial [[embryo]]s form a [[choriovitelline placenta]] (which can be thought of as something between a monotreme egg and a "true" placenta), in which the egg's yolk sac supplies a large part of the embryo's nutrition but also attaches to the uterine wall and takes nutrients from the mother's bloodstream. However, [[bandicoots]] also have a rudimentary chorioallantoic placenta, similar to those of placentals.

{{anchor|Forms in mammals}}

The [[fetus]] usually develops fully in [[Placentalia|placentals]] and only partially in [[marsupial]]s including [[kangaroo]]s and [[opossum]]s. In marsupials, the uterus forms as a duplex organ of two uteri. In monotremes such as the [[platypus]], the uterus is duplex and rather than nurturing the embryo, secretes the shell around the egg. It is essentially identical with the [[oviduct|shell gland]] of birds and reptiles, with which the uterus is [[homology (biology)|homologous]].<ref name=VB>{{cite book |author=Romer, Alfred Sherwood|author2=Parsons, Thomas S.|year=1977 |title=The Vertebrate Body |publisher=Holt-Saunders International |location= Philadelphia, Pennsylvania|pages= 390–392|isbn= 0-03-910284-X}}</ref>

In mammals, the four main forms of the uterus are: duplex, bipartite, bicornuate and simplex.<ref>Lewitus, Eric, and Christophe Soligo. "[https://www.researchgate.net/profile/Eric_Lewitus/publication/226225069_Life-History_Correlates_of_Placental_Structure_in_Eutherian_Evolution/links/5422b6820cf290c9e3ab11f9.pdf Life-history correlates of placental structure in eutherian evolution] {{webarchive|url=https://web.archive.org/web/20170906091408/https://www.researchgate.net/profile/Eric_Lewitus/publication/226225069_Life-History_Correlates_of_Placental_Structure_in_Eutherian_Evolution/links/5422b6820cf290c9e3ab11f9.pdf |date=2017-09-06 }}." Evolutionary Biology 38.3 (2011): 287-305.</ref>
; Duplex: There are two wholly separate uteri, with one oviduct each. Found in [[marsupial]]s (such as [[kangaroo]]s, [[Tasmanian devil]]s, [[opossum]]s, etc.), [[rodent]]s (such as [[mouse|mice]], [[rat]]s, and [[guinea pig]]s), and [[lagomorphs]] ([[rabbit]]s and [[hare]]s).
; Bipartite: The two uteri are separate for most of their length, but share a single cervix. Found in [[ruminant]]s ([[deer]], including [[moose]] and [[elk]], etc.), [[hyrax]]es, [[cat]]s, and [[horse]]s.
; Bicornuate: The upper parts of the uterus remain separate, but the lower parts are fused into a single structure. Found in [[dog]]s, [[pig]]s, [[elephant]]s, [[whale]]s, [[dolphin]]s,<ref name="WürsigPerrin2009">{{cite book|author1=Bernd Würsig|author2=William F. Perrin|author3=J.G.M. Thewissen|title=Encyclopedia of Marine Mammals|url=https://books.google.com/books?id=2rkHQpToi9sC&q=bicornuate+OR+uterus|date=26 February 2009|publisher=Academic Press|isbn=978-0-08-091993-5|access-date=19 October 2020|archive-date=10 April 2021|archive-url=https://web.archive.org/web/20210410044551/https://books.google.com/books?id=2rkHQpToi9sC&q=bicornuate+OR+uterus|url-status=live}}</ref> and [[tarsier]]s, and [[Strepsirrhini|strepsirrhine]] [[primate]]s among others.
; Simplex: The entire uterus is fused into a single organ.<ref name="VB"/> It is found in [[higher primates]], including [[humans]], [[Pan (genus)|chimpanzees]], and [[monkey]]s. Occasionally, some individual females (including humans) may have a [[bicornuate uterus]], a [[uterine malformation]] where the two parts of the uterus fail to fuse completely during fetal development.

Two uteri usually form initially in a female and usually male fetus, and in placental mammals, they may partially or completely fuse into a single uterus depending on the species. In many species with two uteri, only one is functional. Humans and other higher primates such as chimpanzees, usually have a single completely fused uterus, although in some individuals, the uteri may not have completely fused.

== Additional images ==
<gallery>
File:Scheme female reproductive system-en.svg|Schematic frontal view of female anatomy
File:Gray34.png|Sectional plan of the gravid uterus in the third and fourth month
File:Gray38.png|Fetus in utero, between fifth and sixth months
File:Slide4DDD.JPG|Uterus
</gallery>

== See also ==
* [[Artificial uterus]]
* [[Engineered uterus]]
* [[List of distinct cell types in the adult human body]]
* [[Menopause]]
* [[Social uterus]]
* [[Unicornuate uterus]]
* [[Uterus-like mass]]
* [[Gestational sac]]

== References ==
{{Reflist}}

== External links ==
{{Wiktionary|womb|uterus}}
{{Commons category|Uterus|lcfirst=yes}}
* {{SUNYAnatomyLabs|43|01|01|02}}&nbsp;– "The Female Pelvis: Organs in the Female and male Pelvis in situ"
* [http://www.encyclopedia.com/doc/1E1-uterus.html Encyclopedia.com]
* [https://web.archive.org/web/20121026003758/http://medicalterms.info/anatomy/Uterus/ Uterus Anatomy]
* [https://www.zoylo.com/diagnostics/organs/uterus Uterus Pregnancy]

{{Women's health|state=collapsed}}
{{Female reproductive system}}

{{Authority control}}

[[Category:Uterus| ]]
[[Category:Organs (anatomy)]]
[[Category:Pelvis]]
[[Category:Mammal female reproductive system]]
[[Category:Human female reproductive system]]
[[Category:Sex organs]]
[[Category:Women's health]]