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Velamentous umbilical cord insertion and vasa previa

Charles J Lockwood, MD, MHCM
Karen Russo-Stieglitz, MD
Section Editors
Lynn L Simpson, MD
Deborah Levine, MD
Deputy Editor
Vanessa A Barss, MD, FACOG


A velamentous umbilical cord is characterized by membranous umbilical vessels at the placental insertion site; the remainder of the cord is usually normal. Membranous vessels can also arise as aberrant branches of a marginally inserted umbilical cord or they can connect lobes of a bilobed placenta or the placenta and a succenturiate lobe. Because of the lack of protection from Wharton’s jelly, these vessels are prone to compression and rupture, especially when they are located in the membranes covering the cervical os (ie, vasa previa).


Definition — In a velamentous umbilical cord insertion, the placental end of the cord consists of divergent umbilical vessels surrounded only by fetal membranes, with no Wharton's jelly. The length of the membranous vessels, ie, the distance between the end of the normal cord and the placental insertion, is highly variable.

Prevalence — Velamentous insertion occurs in approximately 1 percent of singleton gestations [1], but is observed in as many as 15 percent of monochorionic twin gestations [2-4]. It is also more common in placenta previa than in normally located placentas. The prevalence may be slightly higher in stillbirths, particularly from multifetal pregnancies [4].

Pathogenesis — The pathogenesis of velamentous cord insertion is unknown. The most popular hypothesis is that the cord is initially inserted centrally, but its location progressively becomes peripheral as one half of the placenta actively proliferates toward the well-vascularized uterine fundus (trophotropism) while the other pole involutes; the umbilical cord is unable to follow the migration of the placenta [5]. The association of velamentous cord insertion and placenta previa supports this hypothesis.

Clinical features

Ultrasound and gross examination — On ultrasound and gross examination, the normal umbilical cord sheath is contiguous with the chorionic plate. With a velamentous insertion, the cord can end several centimeters from the placenta, at which point the umbilical vessels separate from each other and cross between the amnion and chorion before connecting to the subchorionic vessels of the placenta (picture 1A-C). This typically occurs at the margin of the placenta (within 1 cm of the placental edge), but can also occur at the apex of the gestational sac. In monochorionic twins, the velamentous vessels often occur in the dividing membranes.

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Literature review current through: Nov 2017. | This topic last updated: Aug 28, 2017.
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  1. Sepulveda W, Rojas I, Robert JA, et al. Prenatal detection of velamentous insertion of the umbilical cord: a prospective color Doppler ultrasound study. Ultrasound Obstet Gynecol 2003; 21:564.
  2. Lopriore E, Sueters M, Middeldorp JM, et al. Velamentous cord insertion and unequal placental territories in monochorionic twins with and without twin-to-twin-transfusion syndrome. Am J Obstet Gynecol 2007; 196:159.e1.
  3. Kent EM, Breathnach FM, Gillan JE, et al. Placental cord insertion and birthweight discordance in twin pregnancies: results of the national prospective ESPRiT Study. Am J Obstet Gynecol 2011; 205:376.e1.
  4. Pinar H, Carpenter M. Placenta and umbilical cord abnormalities seen with stillbirth. Clin Obstet Gynecol 2010; 53:656.
  5. Kouyoumdjian A. Velamentous insertion of the umbilical cord. Obstet Gynecol 1980; 56:737.
  6. Hasegawa J, Matsuoka R, Ichizuka K, et al. Ultrasound diagnosis and management of umbilical cord abnormalities. Taiwan J Obstet Gynecol 2009; 48:23.
  7. BILEK K, ROTHE K, PICKAZECK K. [Hemorrhage of the velamentous insertion before rupture of the membranes]. Zentralbl Gynakol 1962; 84:1536.
  8. Hoyme HE, Jones KL, Van Allen MI, et al. Vascular pathogenesis of transverse limb reduction defects. J Pediatr 1982; 101:839.
  9. Williams JH, Benirschke K. Chorionic vessel thrombosis: a possible etiology of neonatal purpura. J Reprod Med 1978; 20:285.
  10. Vahanian SA, Lavery JA, Ananth CV, Vintzileos A. Placental implantation abnormalities and risk of preterm delivery: a systematic review and metaanalysis. Am J Obstet Gynecol 2015; 213:S78.
  11. Esakoff TF, Cheng YW, Snowden JM, et al. Velamentous cord insertion: is it associated with adverse perinatal outcomes? J Matern Fetal Neonatal Med 2015; 28:409.
  12. Ebbing C, Kiserud T, Johnsen SL, et al. Prevalence, risk factors and outcomes of velamentous and marginal cord insertions: a population-based study of 634,741 pregnancies. PLoS One 2013; 8:e70380.
  13. De Paepe ME, Shapiro S, Young L, Luks FI. Placental characteristics of selective birth weight discordance in diamniotic-monochorionic twin gestations. Placenta 2010; 31:380.
  14. Ebbing C, Kiserud T, Johnsen SL, et al. Third stage of labor risks in velamentous and marginal cord insertion: a population-based study. Acta Obstet Gynecol Scand 2015; 94:878.
  15. Monteagudo A, Sfakianaki AK, Timor-Tritsch IE. Velamentous insertion of the cord in the first trimester. Ultrasound Obstet Gynecol 2000; 16:498.
  16. http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/us/us_obstetrical.aspx (Accessed on February 08, 2012).
  17. Eddleman KA, Lockwood CJ, Berkowitz GS, et al. Clinical significance and sonographic diagnosis of velamentous umbilical cord insertion. Am J Perinatol 1992; 9:123.
  18. Catanzarite V, Maida C, Thomas W, et al. Prenatal sonographic diagnosis of vasa previa: ultrasound findings and obstetric outcome in ten cases. Ultrasound Obstet Gynecol 2001; 18:109.
  19. Lee W, Lee VL, Kirk JS, et al. Vasa previa: prenatal diagnosis, natural evolution, and clinical outcome. Obstet Gynecol 2000; 95:572.
  20. Bronsteen R, Whitten A, Balasubramanian M, et al. Vasa previa: clinical presentations, outcomes, and implications for management. Obstet Gynecol 2013; 122:352.
  21. Rebarber A, Dolin C, Fox NS, et al. Natural history of vasa previa across gestation using a screening protocol. J Ultrasound Med 2014; 33:141.
  22. Oyelese Y, Smulian JC. Placenta previa, placenta accreta, and vasa previa. Obstet Gynecol 2006; 107:927.
  23. Francois K, Mayer S, Harris C, Perlow JH. Association of vasa previa at delivery with a history of second-trimester placenta previa. Obstetrical & Gynecological Survey 2004; 59:245.
  24. Oyelese Y, Spong C, Fernandez MA, McLaren RA. Second trimester low-lying placenta and in-vitro fertilization? Exclude vasa previa. J Matern Fetal Med 2000; 9:370.
  25. Schachter M, Tovbin Y, Arieli S, et al. In vitro fertilization is a risk factor for vasa previa. Fertil Steril 2002; 78:642.
  26. Baulies S, Maiz N, Muñoz A, et al. Prenatal ultrasound diagnosis of vasa praevia and analysis of risk factors. Prenat Diagn 2007; 27:595.
  27. Al-Khaduri M, Kadoch IJ, Couturier B, et al. Vasa praevia after IVF: should there be guidelines? Report of two cases and literature review. Reprod Biomed Online 2007; 14:372.
  28. Hasegawa J, Farina A, Nakamura M, et al. Analysis of the ultrasonographic findings predictive of vasa previa. Prenat Diagn 2010; 30:1121.
  29. Society of Maternal-Fetal (SMFM) Publications Committee, Sinkey RG, Odibo AO, Dashe JS. #37: Diagnosis and management of vasa previa. Am J Obstet Gynecol 2015; 213:615.
  30. Hasegawa J, Nakamura M, Sekizawa A, et al. Prediction of risk for vasa previa at 9-13 weeks' gestation. J Obstet Gynaecol Res 2011; 37:1346.
  31. Swank ML, Garite TJ, Maurel K, et al. Vasa previa: diagnosis and management. Am J Obstet Gynecol 2016; 215:223.e1.
  32. Ruiter L, Kok N, Limpens J, et al. Incidence of and risk indicators for vasa praevia: a systematic review. BJOG 2016; 123:1278.
  33. Lijoi AF, Brady J. Vasa previa diagnosis and management. J Am Board Fam Pract 2003; 16:543.
  34. Catanzarite V, Cousins L, Daneshmand S, et al. Prenatally Diagnosed Vasa Previa: A Single-Institution Series of 96 Cases. Obstet Gynecol 2016; 128:1153.
  35. Sullivan EA, Javid N, Duncombe G, et al. Vasa Previa Diagnosis, Clinical Practice, and Outcomes in Australia. Obstet Gynecol 2017; 130:591.
  36. Antoine C, Young BK, Silverman F, et al. Sinusoidal fetal heart rate pattern with vasa previa in twin pregnancy. J Reprod Med 1982; 27:295.
  37. Melcer Y, Maymon R, Pekar-Zlotin M, et al. Evaluation of the impact of vasa previa on feto-placental hormonal synthesis and fetal growth. Eur J Obstet Gynecol Reprod Biol 2017; 215:193.
  38. Nomiyama M, Toyota Y, Kawano H. Antenatal diagnosis of velamentous umbilical cord insertion and vasa previa with color Doppler imaging. Ultrasound Obstet Gynecol 1998; 12:426.
  39. Ruiter L, Kok N, Limpens J, et al. Systematic review of accuracy of ultrasound in the diagnosis of vasa previa. Ultrasound Obstet Gynecol 2015; 45:516.
  40. Nguyen D, Nguyen C, Yacobozzi M, et al. Imaging of the placenta with pathologic correlation. Semin Ultrasound CT MR 2012; 33:65.
  41. Kikuchi A, Uemura R, Serikawa T, et al. Clinical significances of magnetic resonance imaging in prenatal diagnosis of vasa previa in a woman with bilobed placentas. J Obstet Gynaecol Res 2011; 37:75.
  42. Nimmo MJ, Kinsella D, Andrews HS. MRI in pregnancy: the diagnosis of vasa previa by magnetic resonance imaging. Bristol Med Chir J 1988; 103:12.
  43. Mabuchi Y, Yamoto M, Minami S, et al. Two cases of vasa previa diagnosed prenatally using three-dimensional ultrasonography. J Clin Ultrasound 2010; 38:389.
  44. Araujo Júnior E, Filho HA, Pires CR, et al. Prenatal diagnosis of vasa previa through color Doppler and three-dimensional power Doppler ultrasonography. A case report. Clin Exp Obstet Gynecol 2006; 33:122.
  45. Canterino JC, Mondestin-Sorrentino M, Muench MV, et al. Vasa previa: prenatal diagnosis and evaluation with 3-dimensional sonography and power angiography. J Ultrasound Med 2005; 24:721.
  46. Oyelese Y, Chavez MR, Yeo L, et al. Three-dimensional sonographic diagnosis of vasa previa. Ultrasound Obstet Gynecol 2004; 24:211.
  47. Odunsi K, Bullough CH, Henzel J, Polanska A. Evaluation of chemical tests for fetal bleeding from vasa previa. Int J Gynaecol Obstet 1996; 55:207.
  48. Kumazawa Y, Shimizu D, Hosoya N, et al. Cervical varix with placenta previa totalis. J Obstet Gynaecol Res 2007; 33:536.
  49. Kusanovic JP, Soto E, Espinoza J, et al. Cervical varix as a cause of vaginal bleeding during pregnancy: prenatal diagnosis by color Doppler ultrasonography. J Ultrasound Med 2006; 25:545.
  50. Hurton T, Morrill H, Mascola M, et al. Cervical varices: an unusual etiology for third-trimester bleeding. J Clin Ultrasound 1998; 26:317.
  51. Oyelese Y, Catanzarite V, Prefumo F, et al. Vasa previa: the impact of prenatal diagnosis on outcomes. Obstet Gynecol 2004; 103:937.
  52. Cipriano LE, Barth WH Jr, Zaric GS. The cost-effectiveness of targeted or universal screening for vasa praevia at 18-20 weeks of gestation in Ontario. BJOG 2010; 117:1108.
  53. Hasegawa J, Arakaki T, Ichizuka K, Sekizawa A. Management of vasa previa during pregnancy. J Perinat Med 2015; 43:783.
  54. Vintzileos AM, Ananth CV, Smulian JC. Using ultrasound in the clinical management of placental implantation abnormalities. Am J Obstet Gynecol 2015; 213:S70.
  55. Quintero RA, Kontopoulos EV, Bornick PW, Allen MH. In utero laser treatment of type II vasa previa. J Matern Fetal Neonatal Med 2007; 20:847.
  56. Johnston R, Shrivastava VK, Chmait RH. Term vaginal delivery following fetoscopic laser photocoagulation of type II vasa previa. Fetal Diagn Ther 2014; 35:62.
  57. Robinson BK, Grobman WA. Effectiveness of timing strategies for delivery of individuals with vasa previa. Obstet Gynecol 2011; 117:542.