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Vasa praevia
Vasa praevia
Classification and external resources
Specialty obstetrics
ICD-10 O69.4
ICD-9-CM 663.5
DiseasesDB 13743
eMedicine med/3276

Vasa praevia (vasa previa AE) is an obstetric complication in which fetal blood vessels cross or run near the internal orifice of the uterus. These vessels are at risk of rupture when the supporting membranes rupture, as they are unsupported by the umbilical cord or placental tissue.The term "vasa previa" is derived from the Latin; "vasa" means vessel and "previa" comes from "pre" meaning "before" and "via" meaning "way". In other words, vessels lie before the baby in the birth canal and in the way. [1]


Vasa previa is present when unprotected fetal vessels traverse the fetal membranes over the internal cervical os. These vessels may be from either a velamentous insertion of the umbilical cord or may be joining an accessory (succenturiate) placental lobe to the main disk of the placenta. If these fetal vessels rupture the bleeding is from the fetoplacental circulation, and fetal exsanguination will rapidly occur, leading to fetal death. It is thought that vasa previa arises from an early placenta previa. As the pregnancy progresses, the placenta tissue surrounding the vessels over the cervix undergoes atrophy, and the placenta grows preferentially toward the upper portion of the uterus. This leaves unprotected vessels running over the cervix and in the lower uterine segment. This has been demonstrated using serial ultrasound. Oyelese et al found that 2/3 of patient with vasa previa at delivery had a low-lying placenta or placenta previa that resolved prior to the time of delivery. There are three types of vasa previa. Types 1 and 2 were described by Catanzarite et al. In Type 1, there is a velamentous insertion with vessels running over the cervix. In Type 2, unprotected vessels run between lobes of a bilobed or succenturiate lobed placenta. In Type 3, a portion of the placenta overlying the cervix undergoes atrophy. In this type, there is a normal placental cord insertion and the placenta has only one lobe. However, vessels at a margin of the placenta are exposed.

Risk Factors[edit]

Vasa previa is seen more commonly with velamentous insertion of the umbilical cord, accessory placental lobes (succenturiate or bilobate placenta), multiple gestation, IVF pregnancy. In IVF pregnancies incidences as high as one in 300 have been reported[citation needed]. The reasons for this association are not clear, but disturbed orientation of the blastocyst at implantation, vanishing embryos and the increased frequency of placental morphological variations in in vitro fertilisation pregnancies have all been postulated[citation needed].


  • The classic triad of the vasa praevia is: membrane rupture, painless vaginal bleeding and fetal bradycardia or fetal death.
  • Prior to the advent of ultrasound, this diagnosis was most often made after a stillbirth or neonatal death in which the mother had ruptured her membranes, had some bleeding, and delivered an exsanguinated baby. In these cases, examination of the placenta and membranes after delivery would show evidence of a velamentous cord insertion with rupture of the vessels. However, with almost universal use of ultrasound in the developed world, many cases are now detected during pregnancy, giving the opportunity to deliver the baby before this catastrophic rupture of the membranes occurs. Vasa previa is diagnosed with ultrasound when echolucent linear or tubular structures are found overlying the cervix or in close proximity to it. Transvaginal ultrasound is the preferred modality. Color, power and pulsed wave Doppler should be used to confirm that the structures are fetal vessels. The vessels will demonstrate a fetal arterial or venous waveform.[2][3]
  • Alkali denaturation test detects the presence of fetal hemoglobin in vaginal blood, as fetal hemoglobin is resistant to denaturation in presence of 1% NaOH. Tests such as the Ogita Test, Apt test or Londersloot test were previously used to attempt to detect fetal blood in the vaginal blood, to help make the diagnosis. These tests are no longer widely used in the US, but are sometimes used in other parts of the world.
  • Also detection of fetal hemoglobin in vaginal bleeding is diagnostic.


It is recommended that women with vasa previa should be delivered by elective cesarean prior to rupture of the membranes. Given that the timing of rupture of membranes is difficult to predict, elective cesarean delivery at 35–36 weeks is recommended. This gestational age gives a reasonable balance between the risk of death and that of prematurity. Several authorities have recommended hospital admission at about 32 weeks. This is to give the patient proximity to the operating room for emergency delivery should the membranes rupture. Because these patients are at risk for preterm delivery, it is recommended that steroids should be given to promote fetal lung maturation. When bleeding occurs, the patient goes into labor, or if the membranes rupture, immediate treatment with an emergency caesarean delivery is usually indicated.[4][5]

See also[edit]


  1. ^ Yasmine Derbala, MD; Frantisek Grochal, MD; Philippe Jeanty, MD, PhD (2007). "Vasa previa". Journal of Prenatal Medicine 2007 1 (1): 2–13.  Full text
  2. ^ Lijoi A, Brady J (2003). "Vasa previa diagnosis and management.". J Am Board Fam Pract 16 (6): 543–8. doi:10.3122/jabfm.16.6.543. PMID 14963081. Full text
  3. ^ Lee W, Lee V, Kirk J, Sloan C, Smith R, Comstock C (2000). "Vasa previa: prenatal diagnosis, natural evolution, and clinical outcome.". Obstet Gynecol 95 (4): 572–6. doi:10.1016/S0029-7844(99)00600-6. PMID 10725492. 
  4. ^ Bhide A, Thilaganathan B (2004). "Recent advances in the management of placenta previa.". Curr Opin Obstet Gynecol 16 (6): 447–51. doi:10.1097/00001703-200412000-00002. PMID 15534438. 
  5. ^ Oyelese Y, Smulian J (2006). "Placenta previa, placenta accreta, and vasa previa.". Obstet Gynecol 107 (4): 927–41. doi:10.1097/01.AOG.0000207559.15715.98. PMID 16582134. 

7. Textbook of Obstetrics by D.C. Dutta 7th edition, page 259

External links[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Vasa_praevia — Please support Wikipedia.
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51 news items

BBC News

BBC News
Sat, 15 Mar 2014 09:30:00 -0700

A post mortem examination revealed the cause of death was vasa praevia - a rare condition that affects one in about 2,500 births in the UK. The condition affects 555 babies a year in the UK. Charity Vasa Praevia Raising Awareness says that the survival ...
Sky News
Thu, 22 Nov 2012 18:22:31 -0800

The condition is called vasa praevia. Blood vessels in the placenta grow abnormally and can rupture when a woman's waters break or the baby starts to move down the birth canal. At least one baby is affected by the condition every day in the UK. Women ...

Daily Mail

Daily Mail
Mon, 19 Nov 2012 14:50:00 -0800

In vasa praevia, either the umbilical cord does not grow into the middle of the placenta as it should, but attaches around the edge of the placenta, leaving the blood vessels exposed; or the placenta develops in two parts and the blood vessels grow to ...

Gazette Live

Gazette Live
Mon, 28 Mar 2016 10:03:28 -0700

They also want to raise awareness of vasa praevia. Jo Chubb, neonatal sister at James Cook, said: “We much appreciate Helen and Andy's support and a big thank you to them and everyone who has helped with the fundraising. "We are very grateful for this ...
The Australian
Sun, 19 Jul 2015 00:22:55 -0700

A mother had a rare complication — vasa praevia, affecting about one in 5000 pregnancies — which can lead to life-threatening bleeding. She contacted Melinda Cruz, co-founder of the Miracle Babies Foundation, to ask if other parents had experienced ...

Hertfordshire Mercury

Hertfordshire Mercury
Mon, 26 Jan 2015 23:18:14 -0800

Campaigners point out that when the condition is diagnosed antenatally through an ultrasound scan, the survival rate is 100 per cent – the charity Vasa Praevia Raising Awareness have no records of babies dying once it has been diagnosed prior to birth.

Bristol Post

Bristol Post
Fri, 03 Oct 2014 00:41:15 -0700

Christina said: "It hits women regardless of age or race and there are certain factors that can increase the risk but unless you are aware of Vasa praevia and ask to be tested the NHS will ignore it. This needs to change. I know how it feels to be told ...
Mon, 16 Dec 2013 04:29:30 -0800

Eine große Gefahr bestehe zudem, wenn die Fruchtblase sich öffnet: Befindet sich der Nabelschnuransatz in den Eihäuten direkt oder sehr nahe am inneren Muttermund – Ärzte sprechen von "Vasa praevia" – können die Gefäße der Nabelschnur beim ...

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