Velamentous cord insertion is a complication of pregnancy where the umbilical cord is inserted in the fetal membranes. It is a major cause of antepartum hemorrhage that leads to loss of fetal blood and associated with high perinatal mortality. In normal pregnancies, the umbilical cord inserts into the middle of the placental mass and is completely encased by the amniotic sac. The vessels are hence normally protected by Wharton's jelly, which prevents rupture during pregnancy and labor.[10] In velamentous cord insertion, the vessels of the umbilical cord are improperly inserted in the chorioamniotic membrane, and hence the vessels traverse between the amnion and the chorion towards the placenta.[1][11] Without Wharton's jelly protecting the vessels, the exposed vessels are susceptible to compression and rupture.[1][9]
The exact cause of velamentous cord insertion is unknown, although risk factors include nulliparity,[2][6] the use of assisted reproductive technology,[6][12] maternal obesity,[6][7] and pregnancy with other placental anomalies.[9] Velamentous cord insertion is often diagnosed using an abdominal ultrasound.[3][4] This is most successful in the second trimester,[13] however Color Doppler ultrasound[14] or transvaginal ultrasound[15] can be used in difficult cases, such as when the placenta is located posteriorly. If the woman is diagnosed with velamentous cord insertion, the pregnancy is closely monitored, especially as velamentous cord insertion is a strong risk factor for vasa previa, where the exposed vessels cross the cervix and are at high risk of rupture during membrane rupture in early labor.[9] Management strategies for velamentous cord insertion also involve determining the presence of vasa previa.[16] Velamentous cord insertion impacts fetal development during pregnancy by impairing the development of the placenta[2] and modifying the efficiency of placental function.[17] This can manifest in a range of adverse perinatal outcomes, such as fetal growth restriction,[4][5] placental abruption,[3][6][16][18] abnormal fetal heart rate patterns,[3][10][19] and fetal death.[6][7][9] Velamentous cord insertion affects between 0.1%-1.8% of pregnancies,[6] though its incidence increases ten-fold in multiple pregnancies.[1][10]
^ abcdSepulveda W, Rojas I, Robert J, Schnapp C, Alcalde J (2003). "Prenatal detection of velamentous insertion of the umbilical cord: a prospective color Doppler ultrasound study". Ultrasound in Obstetrics and Gynecology. 21 (6): 564–569. doi:10.1002/uog.132. PMID12808673. S2CID1788491.
^ abEddleman K, Lockwood C, Berkowitz G, Lapinski R, Berkowitz R (1992). "Clinical Significance and Sonographic Diagnosis of Velamentous Umbilical Cord Insertion". American Journal of Perinatology. 9 (2): 123–126. doi:10.1055/s-2007-994684. PMID1590867. S2CID39286973.
^ abcdefghRäisänen S, Georgiadis L, Harju M, Keski-Nisula L, Heinonen S (2012). "Risk factors and adverse pregnancy outcomes among births affected by velamentous umbilical cord insertion: a retrospective population-based register study". European Journal of Obstetrics & Gynecology and Reproductive Biology. 165 (2): 231–234. doi:10.1016/j.ejogrb.2012.08.021. PMID22944380.
^ abcdWiedaseck S, Monchek R (2014). "Placental and Cord Insertion Pathologies: Screening, Diagnosis, and Management". Journal of Midwifery & Women's Health. 59 (3): 328–335. doi:10.1111/jmwh.12189. PMID24751147.
^ abcSinkin J, Craig W, Jones M, Pinette M, Wax J (2018). "Perinatal Outcomes Associated With Isolated Velamentous Cord Insertion in Singleton and Twin Pregnancies". Journal of Ultrasound in Medicine. 37 (2): 471–718. doi:10.1002/jum.14357. PMID28850682. S2CID26888548.
^Paavonen J, Jouttunpää K, Kangasluoma P, Aro P, Heinonen P (1984). "Velamentous insertion of the umbilical cord and vasa previa". International Journal of Gynecology & Obstetrics. 22 (3): 207–211. doi:10.1016/0020-7292(84)90007-9. PMID6148278. S2CID23409481.
^Baulies S, Maiz N, Muñoz A, Torrents M, Echevarría M, Serra B (2007). "Prenatal ultrasound diagnosis of vasa praevia and analysis of risk factors". Prenatal Diagnosis. 27 (7): 595–599. doi:10.1002/pd.1753. PMID17497747. S2CID37634607.
^Toivonen S, Heinonen S, Anttila M, Kosma V, Saarikoski S (2002). "Reproductive Risk Factors, Doppler Findings, and Outcome of Affected Births in Placental Abruption: A Population-Based Analysis". American Journal of Perinatology. 19 (8): 451–460. doi:10.1055/s-2002-36868. PMID12541219. S2CID259998340.
^Hasegawa J, Matsuoka R, Ichizuka K, Kotani M, Nakamura M, Mikoshiba T, Sekizawa A, Okai (2009). "Atypical variable deceleration in the first stage of labor is a characteristic fetal heart-rate pattern for velamentous cord insertion and hypercoiled cord". Journal of Obstetrics and Gynaecology Research. 35 (1): 35–39. doi:10.1111/j.1447-0756.2008.00863.x. PMID19215545. S2CID11157923.