{{Short description|Connection or opening between two things}} [[File:Vein sceleton hydrangea ies.jpg|thumb|right|Vein skeleton of a ''Hydrangea'' leaf showing anastomoses of veins]]
An '''anastomosis''' ({{IPAc-en|ə|ˌ|n|æ|s|t|ə|ˈ|m|oʊ|s|ɪ|s}}, {{plural form}}: '''anastomoses''') is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (such as the foramen ovale in a fetus' heart) or abnormal (such as the patent foramen ovale in an adult's heart); it may be acquired (such as an arteriovenous fistula) or innate (such as the arteriovenous shunt of a metarteriole); and it may be natural (such as the aforementioned examples) or artificial (such as a surgical anastomosis). The reestablishment of an anastomosis that had become blocked is called a reanastomosis. Anastomoses that are abnormal, whether congenital or acquired, are often called fistulas.
The term is used in medicine,<ref>{{Cite web|title=Online ICD9/ICD9CM codes|url=http://icd9cm.chrisendres.com/index.php?srchtype=procs&srchtext=52.7&Submit=Search&action=search|access-date=2022-01-24|website=icd9cm.chrisendres.com}}</ref> biology, mycology, cybernetics, as well as geology, and geography.
==Etymology== Anastomosis: medical or Modern Latin, from Greek ἀναστόμωσις, anastomosis, "outlet, opening", Greek ana- "up, on, upon", stoma "mouth", "to furnish with a mouth".<ref>[http://www.etymonline.com/index.php?term=anastomosis&allowed_in_frame=0 Online Etymology Dictionary] Douglas Harper</ref> Thus the ''-stom-'' syllable is cognate with that of ''stoma'' in botany or ''stoma'' in medicine.
==Medical anatomy== thumb|right|A network of blood vessels An anastomosis is the connection of two normally divergent structures.<ref>{{citation|author1=Gylys, Barbara A. |author2=Mary Ellen Wedding|title=Medical Terminology Systems|publisher=F.A. Davis Company|year=2005}}</ref> It refers to connections between blood vessels or between other tubular structures such as loops of intestine.
===Circulatory=== In circulatory anastomoses, many arteries naturally anastomose with each other; for example, the inferior epigastric artery and superior epigastric artery, or the anterior and/or posterior communicating arteries in the Circle of Willis in the brain. The circulatory anastomosis is further divided into arterial and venous anastomosis. Arterial anastomosis includes actual arterial anastomosis (e.g., palmar arch, plantar arch) and potential arterial anastomosis (e.g. coronary arteries and cortical branch of cerebral arteries). Anastomoses also form alternative routes around capillary beds in areas that do not need a large blood supply, thus helping regulate systemic blood flow.{{citation needed|date=May 2023}}
===Surgical=== Surgical anastomosis occurs when segments of intestine, blood vessel, or any other structure are connected together surgically (anastomosed). Examples include arterial anastomosis in bypass surgery, intestinal anastomosis after a piece of intestine has been resected, Roux-en-Y anastomosis and ureteroureterostomy. Surgical anastomosis techniques include linear stapled anastomosis,<ref name=":0">{{Cite news|url=https://www.sages.org/wiki/laparoscopic-anastomotic-techniques/|title=Laparoscopic Anastomotic Techniques - A SAGES Wiki Article|work=SAGES|access-date=2018-06-28|language=en-US}}</ref> hand sewn anastomosis,<ref name=":0" /> end-to-end anastomosis (EEA).<ref>{{Cite journal|last=Akelina|first=Yelena|date=2014-03-31|title=Microsurgical Technique for 1mm Vessel End to End Anastomosis|journal=Journal of Medical Insight|language=en-US|volume=2014|issue=3|doi=10.24296/jomi/2|issn=2373-6003}}</ref> Anastomosis can be performed by hand or with an anastomosis assist device.<ref>{{Cite journal|last1=Kikuchi|first1=Keita|last2=Tambara|first2=Keiichi|last3=Yamamoto|first3=Taira|last4=Yamasaki|first4=Motoshige|last5=Hirose|first5=Hitoshi|last6=Amano|first6=Atsushi|date=2010|title=The Use of Enclose®II Anastomosis Assist Device for the Proximal Coronary Branch Anastomosis to Vascular Graft|journal=Annals of Vascular Diseases|volume=3|issue=1|pages=84–86|doi=10.3400/avd.hdi08023|issn=1881-641X|pmc=3595814|pmid=23555395}}</ref> Studies have been performed comparing various anastomosis approaches taking into account surgical "time and cost, postoperative anastomotic bleeding, leakage, and stricture".<ref>{{Cite journal|last1=Yao|first1=Libin|last2=Li|first2=Chao|last3=Zhu|first3=Xiaocheng|last4=Shao|first4=Yong|last5=Meng|first5=Song|last6=Shi|first6=Linsen|last7=Wang|first7=Hui|date=2016-11-26|title=An Effective New Intestinal Anastomosis Method|journal=Medical Science Monitor|volume=22|pages=4570–6|doi=10.12659/MSM.902000|issn=1234-1010|pmc=5138069|pmid=27888280}}</ref>
'''Anastomotic leakage (AL) in colorectal cancer surgery'''
Failure of an intestinal anastomosis with leakage of intestinal content in to the abdominal cavity is one of the most severe complications after bowel surgery. The severity of anastomotic leakage varies ranging from mild with minimal impact on the patient to severe and potentially fatal, with negative impact on both short- and long-term outcomes. The incidence has not changed in recent decades, despite improvement in surgical techniques, prehabilitation and perioperative care. Anastomotic leakage after rectal cancer surgery is higher and documented to occur in 9–11%, after colon resection the incidence of leakage is lower and about 6%.<ref name=Snijders12>{{cite journal |vauthors=Snijders HS, Wouters MW, van Leersum NJ, Kolfschoten NE, Henneman D, de Vries AC, Tollenaar RA, Bonsing BA |title=Meta-analysis of the risk for anastomotic leakage, the postoperative mortality caused by leakage in relation to the overall postoperative mortality |journal=Eur J Surg Oncol |volume=38 |issue=11 |pages=1013–9 |date=November 2012 |pmid=22954525 |doi=10.1016/j.ejso.2012.07.111 }}</ref><ref name=Meyer19>{{cite journal |vauthors=Meyer J, Naiken S, Christou N, Liot E, Toso C, Buchs NC, Ris F |title=Reducing anastomotic leak in colorectal surgery: The old dogmas and the new challenges |journal=World J Gastroenterol |volume=25 |issue=34 |pages=5017–25 |date=September 2019 |pmid=31558854 |pmc=6747296 |doi=10.3748/wjg.v25.i34.5017 |doi-access=free }}</ref> Systemic factors contributing to anastomotic failure include sepsis, anemia, diabetes mellitus, previous irradiation, malnutrition, steroid use, smoking, heavy alcohol consumption, obesity and certain disease conditions like Crohn's disease.<ref name=Chen12>{{cite journal |vauthors=Chen C |title=The art of bowel anastomosis |journal=Scand J Surg |volume=101 |issue=4 |pages=238–40 |date=2012 |pmid=23238497 |doi=10.1177/145749691210100403 }}</ref><ref name=Chiarello22>{{cite journal |vauthors=Chiarello MM, Fransvea P, Cariati M, Adams NJ, Bianchi V, Brisinda G |title=Anastomotic leakage in colorectal cancer surgery |journal=Surg Oncol |volume=40 |article-number=101708 |date=March 2022 |pmid=35092916 |doi=10.1016/j.suronc.2022.101708 }}</ref>
Signs of an anastomotic leak include fever, abdominal pain or peritonitis, leukocytosis and tachycardia or new-onset arrythmias. Anastomotic leakage is usually diagnosed 5-8 days post-surgery.<ref name=Chiarello22 /> A CT scan with pneumoperitoneum and significant free fluid or inflammatory changes around the anastomosis are suggestive of an anastomotic failure. Depending on the magnitude of the defect and leak different treatments are indicated. A localized anastomotic leak without systemic sepsis or peritonitis can be managed with antibiotics and if possible, drainage of the abscess. Anastomotic leaks associated with peritonitis or systemic sepsis requires an operation with either revision of the anastomosis if feasible or fecal diversion proximally or at the site of the anastomosis with a stoma.<ref name=Chen12 />
The exact cause of anastomotic leakage remains unclear, but impaired blood supply at the anastomotic site and bacterial activity in the gut have been shown to be associated with its development.<ref>{{cite journal |vauthors=Ma K, Gu T, Wu Z, Li Z |title=Mechanisms of anastomotic leakage in colorectal cancer surgery: unraveling the roles of inflammation, immunity, and microbiota - a narrative review |journal=Int J Surg |volume=111 |issue=12 |pages=9482–95 |date=December 2025 |pmid=40773274 |pmc=12695332 |doi=10.1097/JS9.0000000000003151 }}</ref> Gut microbiota, in particular, Enterococcus faecalis and Pseudomonas aeruginosa, has been shown to degrade collagen at the suture site due to high colleganase activity, therefore contributing to the pathogenesis of leakage. <ref>{{cite journal |vauthors=Lianos GD, Frountzas M, Kyrochristou ID, Sakarellos P, Tatsis V, Kyrochristou GD, Bali CD, Gazouli M, Mitsis M, Schizas D |title=What Is the Role of the Gut Microbiota in Anastomotic Leakage After Colorectal Resection? A Scoping Review of Clinical and Experimental Studies |journal=J Clin Med |volume=13 |issue=22 |date=November 2024 |page=6634 |pmid=39597778 |doi=10.3390/jcm13226634 |doi-access=free |pmc=11594793 }}</ref><ref>{{cite journal |vauthors=Steyer GE, Puchinger M, Pfeifer J |title=Successful Clinical Avoidance of Colorectal Anastomotic Leakage through Local Decontamination |journal=Antibiotics (Basel) |volume=13 |issue=1 |date=January 2024 |page=79 |pmid=38247638 |pmc=10812415 |doi=10.3390/antibiotics13010079 |doi-access=free }}</ref> Patient-related factors, especially diabetes and visceral obesity, remain important independent predictors of anastomotic leakage.<ref>{{cite journal |vauthors=Kang CY, Halabi WJ, Chaudhry OO, Nguyen V, Pigazzi A, Carmichael JC, Mills S, Stamos MJ |title=Risk factors for anastomotic leakage after anterior resection for rectal cancer |journal=JAMA Surg |volume=148 |issue=1 |pages=65–71 |date=January 2013 |pmid=22986932 |doi=10.1001/2013.jamasurg.2 }}</ref>
===Pathological=== Pathological anastomosis results from trauma or disease and may involve veins, arteries, or intestines. These are usually referred to as fistulas. In the cases of veins or arteries, traumatic fistulas usually occur between artery and vein. Traumatic intestinal fistulas usually occur between two loops of intestine (entero-enteric fistula) or intestine and skin (enterocutaneous fistula). Portacaval anastomosis, by contrast, is an anastomosis between a vein of the portal circulation and a vein of the systemic circulation, which allows blood to bypass the liver in patients with portal hypertension, often resulting in hemorrhoids, esophageal varices, or caput medusae.{{citation needed|date=May 2023}}
==Biology==
===Evolution=== In evolution, anastomosis is a recombination of evolutionary lineage. Conventional accounts of evolutionary lineage present themselves as the branching out of species into novel forms. Under anastomosis, species might recombine after initial branching out, such as in the case of recent research that shows that ancestral populations along human and chimpanzee lineages may have interbred after an initial branching event.<ref>{{cite journal | last = Patterson | first = Nick |date=May 2006 | title = Genetic evidence for complex speciation of humans and chimpanzees | journal = Nature | volume = 441 | pages = 1103–8 | doi = 10.1038/nature04789 | pmid = 16710306 | issue = 7097 |display-authors=etal| bibcode = 2006Natur.441.1103P | s2cid = 2325560 }}</ref> The concept of anastomosis also applies to the theory of symbiogenesis, in which new species emerge from the formation of novel symbiotic relationships.{{citation needed|date=May 2023}}
===Mycology=== [[File:WCB5812-m.jpg|thumb|right|Anastomosing gills of Marasmius cf. cladophyllus]]
In mycology, anastomosis is the fusion between branches of the same or different hyphae.<ref>{{citation|author =Kendrick, Bryce|title=The Fifth Kingdom|publisher=Mycologue Publications|year=2001}}</ref> Hence the bifurcating fungal hyphae can form true reticulating networks. By sharing materials in the form of dissolved ions, hormones, and nucleotides, the fungus maintains bidirectional communication with itself. The fungal network might begin from several origins; several spores (i.e. by means of conidial anastomosis tubes), several points of penetration, each a spreading circumference of absorption and assimilation. Once encountering the tip of another expanding, exploring self, the tips press against each other in pheromonal recognition or by an unknown recognition system, fusing to form a genetic singular clonal colony that can cover hectares called a genet or just microscopical areas.<ref>{{cite journal |author1=Glass L. |author2=Rasmussen C. |author3=Roca M.G. |author4=Read N. | year = 2004 | title = Hyphal homing, fusion and mycelial interconnectedness | journal = Trends in Microbiology | volume = 12 | issue = 3| pages = 135–141 | doi=10.1016/j.tim.2004.01.007|pmid=15001190 |bibcode=2004TrMic..12..135G }}</ref>
For fungi, anastomosis is also a component of reproduction. In some fungi, two different haploid mating types – if compatible – merge. Somatically, they form a morphologically similar mycelial wave front that continues to grow and explore. The significant difference is that each septated unit is binucleate, containing two unfused nuclei, i.e. one from each parent that eventually undergoes karyogamy and meiosis to complete the sexual cycle.{{citation needed|date=May 2023}}
Also the term "anastomosing" is used for mushroom gills which interlink and separate to form a network.<ref name=Bon>{{cite book |author =Marcel Bon |title=The Mushrooms and Toadstools of Britain and North-Western Europe |publisher=Hodder & Stoughton |year=1987 |page=14 |isbn=978-0-340-39935-4 }}</ref>
=== Botany === {{Main|Inosculation}} The growth of a strangler fig around a host tree, with tendrils fusing together to form a mesh, is called anastomosing.<ref>{{Cite book|title=The New Neotropical Companion|last=Kricher|first=John C.|publisher=Princeton University Press|year=2017|isbn=978-1400885589|edition=Revised|location=Princeton, New Jersey|pages=52|oclc=964359395}}</ref>
== Cybernetics ==
=== Anastomotic reticulum === {{Main|Viable system model}} In management cybernetics, Stafford Beer used the term "anastomotic reticulum" to refer to a particular type of tangled network of connections between inputs and outputs, such that it is difficult to trace the flow of messages through the network.<ref name=":1">{{Cite book |last=Beer |first=Stafford |author-link=Stafford Beer |title=Brain of the Firm |publisher=John Wiley & Sons Ltd. |year=1981 |isbn=0-471-27687-1 |edition=2nd |language=en}}</ref><sup>:30–33</sup> Due to the complexity involved, the internal operation of such a structure is difficult to analyze and describe, and so the whole network should instead be viewed as a black box. According to Beer, viable systems reveal many such networks, and are therefore best understood in these terms.<ref name=":1" /><sup>:66–67</sup>
==Geosciences==
===Geology=== In geology, veins of quartz (or other) minerals can display anastomosis.<ref name="DoradoMolano2018">{{cite journal | title=Microthermometry and Raman spectroscopy of fluid inclusions from El Vapor gold mineralizations, Colombia | author=C.E. Dorado J.C. Molano | journal=Earth Sciences Research Journal | year=2018 | volume=22 | issue=3 | pages=151–8 | doi=10.15446/esrj.v22n3.63442 | bibcode=2018ESRJ...22..151D | doi-access=free }}</ref>
Ductile shear zones frequently show anastomosing geometries of highly-strained rocks around lozenges of less-deformed material.<ref>{{Cite journal |last1=Burg |first1=J.-P. |last2=Arbaret |first2=L. |last3=Chaudhry |first3=N. M. |last4=Dawood |first4=H. |last5=Hussain |first5=S. |last6=Zeilinger |first6=G. |date=January 2005 |title=Shear strain localization from the upper mantle to the middle crust of the Kohistan Arc (Pakistan) |url=https://www.lyellcollection.org/doi/10.1144/GSL.SP.2005.245.01.02 |journal=Geological Society, London, Special Publications |language=en |volume=245 |issue=1 |pages=25–38 |doi=10.1144/GSL.SP.2005.245.01.02 |bibcode=2005GSLSP.245...25B |s2cid=129641276 |issn=0305-8719|url-access=subscription }}</ref>
Molten lava flows sometimes flow in anastomosed lava channels<ref name="DietterichCashman2011">{{cite conference | last1=Dietterich| first1=H.R. | last2=Cashman | first2=K.V. |url=https://ui.adsabs.harvard.edu/abs/2011AGUFM.V41A2484D/abstract | title=The creation and influence of bifurcations and confluences in Hawaiian lava flows on conditions of flow emplacement | bibcode=2011AGUFM.V41A2484D | accessdate=17 October 2023 | conference=American Geophysical Union, Fall Meeting 2011 | id=V41A-2484}}</ref> or lava tubes.<ref name="Peterson_etal_1994">{{cite journal | title=Development of lava tubes in the light of observations at Mauna Ulu, Kilauea Volcano, Hawaii | first1=D.W. | last1=Peterson | first2=R.T. | last2=Holcomb |first3=R.I. | last3=Tilling | first4=R.L. | last4=Christiansen | journal=Bulletin of Volcanology | date=1994 | volume=56 | issue=5 | pages=343–360 | doi=10.1007/BF00326461| bibcode=1994BVol...56..343P | s2cid=129741130 }}</ref>
In cave systems, anastomosis is the splitting of cave passages that later reconnect.<ref>{{cite web |url=http://www.speleogenesis.info/directory/glossary/?term=anastomosis |title=Glossary of Karst and Cave Terms: anastomosis |website=www.speleogenesis.info |access-date=8 July 2022 |archive-date=5 October 2022 |archive-url=https://web.archive.org/web/20221005145303/http://www.speleogenesis.info/directory/glossary/?term=anastomosis |url-status=dead }}</ref>
===Geography and hydrology===
'''Anastomosing rivers''', '''anastomosing streams''' consist of multiple channels that divide and reconnect and are separated by semi-permanent banks formed of cohesive material, such that they are unlikely to migrate from one channel position to another. They can be confused with ''braided rivers'' based on their planforms alone, but braided rivers are much shallower and more dynamic than anastomosing rivers. Some definitions require that an anastomosing river be made up of interconnected channels that enclose floodbasins,<ref>{{cite journal| title=Anastomosing rivers: a review of their classification, origin and sedimentary products| author=Makaske, Bart| journal=Earth-Science Reviews| volume=53| issue=3–4| year=2001| pages=149–196| url=http://www.geo.arizona.edu/geo5xx/geos544/pdfs/fluvial/makaske.pdf| doi=10.1016/s0012-8252(00)00038-6| bibcode=2001ESRv...53..149M| access-date=2016-08-21| archive-url=https://web.archive.org/web/20161011091819/http://www.geo.arizona.edu/geo5xx/geos544/pdfs/fluvial/makaske.pdf| archive-date=2016-10-11| url-status=dead}}</ref> again in contrast with braided rivers.
Rivers with anastomosed reaches include the Magdalena River in Colombia,<ref>{{cite journal|doi=10.1016/0037-0738(86)90058-8|title=Anastomosing river deposits, sedimentation rates and basin subsidence, Magdalena River, northwestern Colombia, South America|year=1986|last1=Smith|first1=D|journal=Sedimentary Geology|volume=46|pages=177–196|issue=3–4|bibcode=1986SedG...46..177S}}</ref> the upper Columbia River in British Columbia, Canada,<ref>{{cite conference |vauthors=Abbado D, Slingerland RL, Smith ND |title=The origin of anastomosis in the upper Columbia River, British Columbia, Canada |book-title=Fluvial Sedimentology VII |publisher=International Association of Sedimentologists |veditors=Blum MD, Marriott S, Leclair S |date=2005 |isbn=978-1-4443-0435-0 |pages= |doi=10.1002/9781444304350.ch1 |series=IAS Special Publication |volume=35}}</ref> the Drumheller Channels of the Channeled Scablands of the state of Washington, US, the Furos de Breves in the Brazilian Amazon Delta, and the upper Narew River in Poland.<ref>{{cite journal|doi=10.1016/S0037-0738(02)00236-1|title=Vegetation-controlled modern anastomosing system of the upper Narew River (NE Poland) and its sediments|year=2003|last1=Gradzinski|first1=R|journal=Sedimentary Geology|volume=157|pages=253–276|issue=3–4|bibcode=2003SedG..157..253G }}</ref> The term anabranch has been used for segments of anastomosing rivers.
Braided streams show anastomosing channels around channel bars of alluvium.<ref>{{Cite journal |last=Whitcomb |first=Lawrence |date=1947 |title=Anastomosing Vs. Braided Streams |url=https://www.jstor.org/stable/44112178 |journal=Proceedings of the Pennsylvania Academy of Science |volume=21 |pages=64–68 |jstor=44112178 |issn=0096-9222}}</ref>
==References== {{reflist}}
Category:Angiology Category:Digestive system Category:Evolutionary biology Category:Petrology Category:Surgery