Velamentous cord insertion
Citation, DOI & article data
The estimated incidence is ~1% in singleton and 9-15% in twin pregnancies, respectively 11. 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.
In a velamentous cord insertion, the umbilical cord inserts into the fetal (chorio-amniotic) membranes outside the placental margin and then travels within the membranes to the placenta (between the amnion and the chorion). It is thought to result from remodeling of the placenta as a response to factors that affect the distribution of uterine blood flow (a process known as trophotropism 5). A marginal cord insertion may evolve into a velamentous cord insertion as the pregnancy progresses 6. Some also support an abnormal primary implantation due to the obliquity of the embryo during implantation as a cause.
- bilobed placenta
- increased incidence in twin pregnancy
- uterine anomalies 10
- presence of an intrauterine contraceptive device (IUCD) 10
- single umbilical artery 6
- placenta previa
Ultrasound allows direct visualization of the cord implantation to a site outside the placenta.
A velamentous cord insertion may be detected as early as the first-trimester scan 4. Antenatal ultrasound is considered to have a variable sensitivity (69-100%) but high specificity (99-100%) for revealing abnormal placental cord insertion sites, including velamentous insertions 5,8.
Color Doppler greatly aids in identification.
- type I vasa previa
- increased risk of intrauterine growth restriction (IUGR)
- increased risk of growth discordance if in a twin pregnancy
- increased risk of twin to twin transfusion syndrome
Treatment and prognosis
Treatment somewhat depends on the location of velamentous vessels and if in the lower segment, a cesarean section to avoid the risks of a vasa previa is often considered.
- Battledore placenta (marginal cord insertion)
- 1. 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 (6): 426-9. doi:10.1046/j.1469-0705.1998.12060426.x - Pubmed citation
- 2. Elsayes KM, Trout AT, Friedkin AM et-al. Imaging of the placenta: a multimodality pictorial review. Radiographics. 29 (5): 1371-91. doi:10.1148/rg.295085242 - Pubmed citation
- 3. 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 (6): 564-9. doi:10.1002/uog.132 - Pubmed citation
- 4. Sepulveda W. Velamentous insertion of the umbilical cord: a first-trimester sonographic screening study. J Ultrasound Med. 2006;25 (8): 963-8. J Ultrasound Med (full text) - Pubmed citation
- 5. Di salvo DN, Benson CB, Laing FC et-al. Sonographic evaluation of the placental cord insertion site. AJR Am J Roentgenol. 1998;170 (5): 1295-8. AJR Am J Roentgenol (abstract) - Pubmed citation
- 6. Pretorius DH, Chau C, Poeltler DM et-al. Placental cord insertion visualization with prenatal ultrasonography. J Ultrasound Med. 1996;15 (8): 585-93. J Ultrasound Med (abstract) - Pubmed citation
- 7. Raga F, Ballester MJ, Osborne NG et-al. Role of color flow Doppler ultrasonography in diagnosing velamentous insertion of the umbilical cord and vasa previa. A report of two cases. J Reprod Med. 1995;40 (11): 804-8. - Pubmed citation
- 8. 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 (6): 426-9. doi:10.1046/j.1469-0705.1998.12060426.x - Pubmed citation
- 9. Benirschke K, Kaufmann P. Pathology of the human placenta. Springer Verlag. (2000) ISBN:0387988947. Read it at Google Books - Find it at Amazon
- 10. Dudiak CM, Salomon CG, Posniak HV et-al. Sonography of the umbilical cord. Radiographics. 1995;15 (5): 1035-50. Radiographics (abstract) - Pubmed citation
- 11. Fadl S, Moshiri M, Fligner CL, Katz DS, Dighe M. Placental Imaging: Normal Appearance with Review of Pathologic Findings. Radiographics : a review publication of the Radiological Society of North America, Inc. 37 (3): 979-998. doi:10.1148/rg.2017160155 - Pubmed