History

Fact Explanation
Vaginal bleeding In vasa previa fetal vessels travel between the presenting part of the fetus and the internal cervical os. Since these vessels are not contained within the placenta or umbilical cord they cause painless vaginal bleeding at second and third trimesters or at the time of artificial or spontaneous rupture of membranes. Clinical diagnosis of vasa previa can be made in the presence of painless vaginal bleeding, ruptured membranes and fetal distress. [1,4]
Risk factors Prenatally diagnosed low lying placenta, placenta previa, bi-lobed or multi-lobed placenta, velamentous cord insertion, multi-fetal pregnancy, and assisted conception are risk factors of vasa previa. [1,2,3]
References
  1. PRINCE GD. Unruptured vasa previa with anomalous umbilical cord formation: A case of postpartum physician tachycardia Can Fam Physician [online] 2013 Oct, 59(10):1076-1078 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3796974
  2. GARRETTO D, BUDORICK NE, FIGUEROA R. Antenatal diagnosis of velamentous cord insertion and vasa previa: preparing for a good outcome when the cervix is shortened. J Ultrasound Med [online] 2012 Jun, 31(6):963-5 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22644694
  3. KAJIMOTO E, MATSUZAKI S, MATSUZAKI S, TANAKA Y, KINUGASA-TANIGUCHI Y, MIMURA K, KANAGAWA T, KIMURA T. Challenges in Diagnosis of Pseudo Vasa Previa Case Rep Obstet Gynecol [online] 2014:903920 [viewed 24 August 2014] Available from: doi:10.1155/2014/903920
  4. NEUHAUSSER WM, BAXI LV. A close call: does the location of incision at cesarean delivery matter in patients with vasa previa? A case report. F1000Res [online] :267 [viewed 24 August 2014] Available from: doi:10.12688/f1000research.2-267.v1

Examination

Fact Explanation
Pervaginal examination When the patient is in labor, pervaginal examination will enable the diagnosis of vasa previa by palpating the vessels. However vasa pervia should be diagnosed well before the established labor with ultrasound scan. [1]
Fetal heart sounds Fetal bradycardia (heart rate less than 110 beats per minute) can be detected with bleeding. [1]
References
  1. GARRETTO D, BUDORICK NE, FIGUEROA R. Antenatal diagnosis of velamentous cord insertion and vasa previa: preparing for a good outcome when the cervix is shortened. J Ultrasound Med [online] 2012 Jun, 31(6):963-5 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22644694

Differential Diagnoses

Fact Explanation
Placenta previa Placenta which has implanted over or adjacent to the carvical os is referred to as placenta previa. Patients present with painless vaginal bleeding. [1]
Placental abruption Painfull vaginal bleeding is commonly seen with placental abruption. Maternal hypovolemia, collapse, shock and death are common complications. [2]
Uterine rupture Uterine rupture is rare but life threatening complication. The risk of uterine rupture is high in patients with a history of uterine surgery and cesarean section. [3]
References
  1. HARPER LM, ODIBO AO, MACONES GA, CRANE JP, CAHILL AG. Effect of Placenta Previa on Fetal Growth Am J Obstet Gynecol [online] 2010 Oct, 203(4):330.e1-330.e5 [viewed 24 August 2014] Available from: doi:10.1016/j.ajog.2010.05.014
  2. ANANTH C. V.. Placental Abruption and Perinatal Mortality in the United States. [online] 2001 February, 153(4):332-337 [viewed 24 August 2014] Available from: doi:10.1093/aje/153.4.332
  3. GUèYE MAMOUR, MBAYE MAGATTE, NDIAYE-GUèYE MAME DIARRA, KANE-GUèYE SERIGNE MODOU, DIOUF ABDOUL AZIZ, NIANG MOUHAMADOU MANSOUR, DIAW HANNEGRET, MOREAU JEAN CHARLES. Spontaneous Uterine Rupture of an Unscarred Uterus before Labour. Case Reports in Obstetrics and Gynecology [online] 2012 December, 2012:1-3 [viewed 24 August 2014] Available from: doi:10.1155/2012/598356

Investigations - for Diagnosis

Fact Explanation
Trans-abdominal ultrasound scan Trans-abdominal ultrasound scan is helpful in detecting vasa previa. In addition it is helpful in detecting the type of vasa previa. Velamentous insertion of the cord is categorized as type 1 and if the vessels are running between a succenturiate placenta and main placental mass or between lobes of a bilobed placenta it is a type 2 vasa previa. [1,2]
Trans-vaginal ultrasound scan Although relatively more invasive than the trans-abdominal ultrasound scan, trans-vaginal scan is more sensitive in diagnosing vasa previa. It is visualized as paired vessel echoes in trans-vaginal scan. [1]
Cardiotocogram Fetal heart rate shows fetal bradycardia, decelerations and sinusoidal pattern. [1]
References
  1. PRINCE GD. Unruptured vasa previa with anomalous umbilical cord formation: A case of postpartum physician tachycardia Can Fam Physician [online] 2013 Oct, 59(10):1076-1078 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3796974
  2. NEUHAUSSER WM, BAXI LV. A close call: does the location of incision at cesarean delivery matter in patients with vasa previa? A case report. F1000Res [online] :267 [viewed 24 August 2014] Available from: doi:10.12688/f1000research.2-267.v1

Investigations - Fitness for Management

Fact Explanation
Amniocentesis Amniocentesis and estimation of fetal lung maturity is indicated as early cesarean delivery is anticipated. This should be done at 36 weeks of gestation. [1]
References
  1. GARRETTO D, BUDORICK NE, FIGUEROA R. Antenatal diagnosis of velamentous cord insertion and vasa previa: preparing for a good outcome when the cervix is shortened. J Ultrasound Med [online] 2012 Jun, 31(6):963-5 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22644694

Investigations - Screening/Staging

Fact Explanation
Ultrasound scan Localization of the placenta is important in every pregnancy, but very important in females with risk factors for vasa previa. Since universal screening is not recommended, transvaginal color Doppler scan on suspicion of vasa previa is indicated for better visualization of the vessels. This should be done during the second trimester. [1,2]
References
  1. PRINCE GD. Unruptured vasa previa with anomalous umbilical cord formation: A case of postpartum physician tachycardia Can Fam Physician [online] 2013 Oct, 59(10):1076-1078 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3796974
  2. IOANNOU C., WAYNE C.. Diagnosis and management of vasa previa: a questionnaire survey. Ultrasound Obstet Gynecol [online] 2010 February, 35(2):205-209 [viewed 24 August 2014] Available from: doi:10.1002/uog.7466

Management - General Measures

Fact Explanation
Health education Patients with vasa previa should be well advised about the diagnosis and possible complications like, vaginal bleeding, fetal loss and need of early cesarean section.
References

Management - Specific Treatments

Fact Explanation
Elective cesarean section In the presence of vasa previa vaginal delivery carries a high risk of fetal mortality rate. Early and elective Cesarean section, around 38 weeks of gestation is indicated in all pregnant ladies with vasa previa. [1,2,3]
Cervical cerclage Although not clearly proven cervical circlage is beneficial in patients with short cervix and in patients with a history of second-trimester miscarriages or preterm births. [2]
References
  1. PRINCE GD. Unruptured vasa previa with anomalous umbilical cord formation: A case of postpartum physician tachycardia Can Fam Physician [online] 2013 Oct, 59(10):1076-1078 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3796974
  2. GARRETTO D, BUDORICK NE, FIGUEROA R. Antenatal diagnosis of velamentous cord insertion and vasa previa: preparing for a good outcome when the cervix is shortened. J Ultrasound Med [online] 2012 Jun, 31(6):963-5 [viewed 24 August 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22644694
  3. IOANNOU C., WAYNE C.. Diagnosis and management of vasa previa: a questionnaire survey. Ultrasound Obstet Gynecol [online] 2010 February, 35(2):205-209 [viewed 24 August 2014] Available from: doi:10.1002/uog.7466