Hyrtl’s anastomosis, the only connection between the two umbilical arteries. A study in full term placentas from AGA infants with normal umbilical artery blood flow

Ullberg, Ulla; Sandstedt, Bengt; Lingman, Göran

doi:10.1034/j.1600-0412.2001.800101.x

Cited by 28 publications

(47 citation statements)

References 16 publications

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“…1B). The diameters, D 1 ϭ D2 ϭ 4 mm, and arterial length, 80 mm, where L up ϭ Ldown ϭ 40 mm of the umbilical arteries, as well as the geometry of the Hyrtl anastomosis (D anast ϭ 4 mm, Lanast ϭ 8 mm), were chosen from averaged morphometric data (17)(18)(19)25). The downstream resistance of the arterial vasculature in the placental territories, which are supplied by each umbilical artery, is represented by a cylindrical porous media of length L porous ϭ 20 mm (Fig.…”

Section: Methodsmentioning

confidence: 99%

Hemodynamic analysis of Hyrtl anastomosis in human placenta

Gordon¹,

Eytan²,

Jaffa³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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The Hyrtl anastomosis is a common connection between the umbilical arteries near the cord insertion in most human placentas. It has been speculated that it equalizes the blood pressure between the territories supplied by the umbilical arteries. However, its functional role in the regulation and distribution of fetal blood flow to the placenta has not yet been explored. A computational model has been developed for quantitative analysis of hemodynamic characteristic of the Hyrtl anastomosis in cases of discordant blood flow in the umbilical arteries. Simulations were performed for cases of either increased placental resistance at the downstream end or reduced arterial blood flow due to some pathologies upstream of one of the arteries. The results indicate that when placental territories of one artery impose increased resistance to fetal blood flow, the Hyrtl anastomosis redistributes the blood flow into the second artery to reduce the large pressure gradients that are developed in the affected artery. When one of the arteries conducts a smaller blood flow into the placenta and a relatively smaller pressure gradient is developed, the Hyrtl anastomosis rebuilds the pressure gradients in the affected artery and redistributes blood flow from the unaffected artery to the affected one to improve placental perfusion. In conclusion, the Hyrtl anastomosis plays the role of either a safety valve or a pressure stabilizer between the umbilical arteries at the placental insertion.

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Section: Methodsmentioning

confidence: 99%

Hemodynamic analysis of Hyrtl anastomosis in human placenta

Gordon¹,

Eytan²,

Jaffa³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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show abstract

“…Hyrtl's anastomosis between the two umbilical arteries of single pregnancies has been described in pathological reports 6 , with the assumption that they influence the blood pressure in the placental bed and between the umbilical arteries 7 . We speculate that a fenestration occurred between the two umbilical vein walls because of their proximity.…”

Section: Letters To the Editormentioning

confidence: 99%

Prenatal diagnosis of forked umbilical cord in monochorionic diamniotic pregnancy with venovenous anastomosis: a form of umbilical cord conjoined twins

Thomas

Dargent

Brans

et al. 2006

Ultrasound in Obstet & Gyne

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“…Functionally, Predanic et al (7) observed a small difference in resistance to blood flow between the two umbilical arteries, which diminished during late pregnancy indicating a functional maturation or adaptation of the anastomosis. In a few cases with perfectly symmetric umbilical artery supply areas, lack of anastomosis has been observed suggesting regression of even the last connection when shunting is not needed (1). The main function of Hyrtl's anastomosis is probably to equalize the flow and pressure in the two arterial placental vascular territories (10).…”

Section: Discussionmentioning

confidence: 99%

“…After thawing, the arterial tree of each placenta was filled with barium X-ray contrast medium and angiograms achieved in two perpendicular projections as described in earlier work (1,13). The anastomosis was measured and characterized in the angiograms according to our previous study in placentas from full-term AGA infants with normal umbilical artery blood flow (1).…”

Section: <0001mentioning

confidence: 99%

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Hyrtl's anastomosis is normally developed in placentas from small for gestational age infants

Ullberg¹,

Lingman²,

Ekman-Ordeberg³

et al. 2003

Acta Obstet Gynecol Scand

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Hyrtl's anastomosis is normally developed in placentas from small for gestational age infants.Ullberg, Ulla; Lingman, Göran; Ekman-Ordeberg, Gunvor; Sandstedt, Bengt Link to publication Citation for published version (APA): Ullberg, U., Lingman, G., Ekman-Ordeberg, G., & Sandstedt, B. (2003). Hyrtl's anastomosis is normally developed in placentas from small for gestational age infants. Acta Obstetricia et Gynecologica Scandinavica, 82(8), 716-721. DOI: 10.1034/j.1600-0412.2003 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Background. The aim of this study was to investigate the occurrence and appearance of the anastomosis between the two umbilical arteries in placentas from infants small for gestational age (SGA). Methods. The arterial systems of 64 placentas from singleton pregnancies resulting in SGA infants were visualized by angiography. The method allowed study of the anastomosis between the umbilical arteries and calculation of the relative placental area supplied by each artery. The results were compared with findings in a previous study of appropriate for gestational age (AGA) infants. One-way analysis of variance (ANOVA) and w 2 -analyses were used for statistics. Results. In 56 placentas the anastomosis was represented by a true vessel, in two by a fenestration, and in another two cases by fusion of the umbilical arteries. The anastomosis was absent in one case and another three cases had a single umbilical artery (SUA). When the diameter of the anastomosis was thinner than that of the umbilical arteries, their supply areas were significantly (p 0.001) more symmetrical than in cases with a wider anastomosis.The anatomy of the anastomosis and the relationship between its width and the symmetry between the supply areas of each umbilical artery did not differ in placentas from SGA and AGA infants, despite various types of cord insertion and placentation. Conclusion. Static measurements of Hyrtl's anastomosis do not indicate a contributing part for intrauterine growth retardation.

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Hyrtl’s anastomosis, the only connection between the two umbilical arteries. A study in full term placentas from AGA infants with normal umbilical artery blood flow

Abstract: By using angiography we were able to demonstrate the variable anatomy of the anastomosis of Hyrtl. We found the occurrence and width of the anastomosis was correlated to the symmetry in size between the supply areas of each umbilical artery.

Cited by 28 publications

References 16 publications

Hemodynamic analysis of Hyrtl anastomosis in human placenta

Hemodynamic analysis of Hyrtl anastomosis in human placenta

Prenatal diagnosis of forked umbilical cord in monochorionic diamniotic pregnancy with venovenous anastomosis: a form of umbilical cord conjoined twins

Hyrtl's anastomosis is normally developed in placentas from small for gestational age infants

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