Vasa previa: when antenatal diagnosis can change fetal prognosis

OBJECTIVES

Evaluate ultrasound diagnostic accuracy, maternal-fetal characteristics and outcomes in case of vasa previa diagnosed antenatally, postnatally or with spontaneous resolution before delivery.

METHODS

Monocentric retrospective study enrolling women with antenatal or postnatal diagnosis of vasa previa at Sant'Anna Hospital in Turin from 2007 to 2018. Vasa previa were defined as fetal vessels that lay 2 cm within the uterine internal os using 2D and Color Doppler transvaginal ultrasound. Diagnosis was confirmed at delivery and on histopathological exam. Vasa previa with spontaneous resolutions were defined as fetal vessels that migrate >2 cm from uterine internal os during scheduled ultrasound follow-ups in pregnancy.

RESULTS

We enrolled 29 patients (incidence of 0.03%). Ultrasound antenatally diagnosed 25 vasa previa (five had a spontaneous resolution) while four were diagnosed postnatally, with an overall sensitivity of 96.2%, specificity of 100%, positive predictive value of 96.2%, and negative predictive value of 100%. Early gestational age at diagnosis is significally associate with spontaneously resolution (p 0.023; aOR 1.63; 95% IC 1.18-2.89). Nearly 93% of our patient had a risk factor for vasa previa: placenta previa at second trimester or low-lying placenta, bilobated placenta, succenturiate cotyledon, velametous cord insertion or assisted reproduction technologies.

CONCLUSIONS

Maternal and fetal outcomes in case of vasa previa antenatally diagnosed are significally improved. Our data support the evaluation of umbilical cord insertion during routine second trimester ultrasound and a targeted screening for vasa previa in women with risk factor: it allows identification of fetus at high risk, reducing fetal mortality in otherwise healthy newborns.

Velamentous Umbilical Cord Insertion and Ruptured Fetal Vessel: A Cause of Fetal-Maternal Hemorrhage: A Case Report

BACKGROUND

Fetal hemorrhage is rare but can result in rapid fetal compromise. Abnormally located fetal vessels within the membranes increase the risk for their rupture and subsequent hemorrhage. The classic example of this is vasa previa.

CASE

We present a case of acute fetal hemorrhage resulting from a ruptured fetal vessel. During induction of labor, significant fetal heart rate deceleration occurred, coinciding with acute vaginal bleeding and amniotomy. A depressed, live female neonate was delivered by emergency cesarean section. Examination of the placenta revealed a velamentous cord insertion and a ruptured fetal vessel coursing through the chorioamniotic membranes. Neonatal resuscitation included red blood cell transfusion for hypotension and low hematocrit. The neonate made a full recovery.

CONCLUSION

Acute fetal hemorrhage from the rupture of aberrant fetal vessels often coincides with rupture of membranes. Identifying ruptured fetal vessels abnormally coursing through the chorioamniotic membranes on examination of the placenta provides supporting evidence for suspected fetal hemorrhage.

Velamentous insertion of the umbilical cord vessels with vasa praevia--a case report

Among the abnormal cord insertion pathology, velamentous cord insertion associated with rupture of vasa praevia is the most severe condition related to the outcome of the newborn. In velamentous cord insertion, the fetal vessels run freely through the fetal membranes without protection from Wharton's jelly, umbilical vessels diverging as they traverse the membranes. When the membranes are ruptured, complete tearing of fetal vessels through the torn membranes or partial rupture near the site of membrane rupture may occur. Velamentous insertion occurs in approximately 1% of singleton gestations, but is observed in as many as 15% of monochorionic twin gestations. The risk of perinatal death was doubled in pregnancies with velamentous cord insertion relative to normal cord insertion. This condition can be diagnosed by ultrasonography with a sensitivity of 67% and specificity of 100% in the second trimester. We report a case of a newborn who came from a velamentous cord insertion condition associated with rupture of vasa praevia after the spontaneously membranes rupture. After a difficult resuscitation and stabilization, the newborn survived with a good outcome after the follow-up.

Vasa praevia: risk-adapted modification of the conventional management--a retrospective study

PURPOSE

Undiagnosed vasa praevia carries an imminent risk of fetal death and increases with IVF. When diagnosed, the question arises as to whether the conventional prenatal management of routine steroid administration for fetal lung maturation and elective caesarean section in week 35 is generally justified in face of the risks involved. We present a retrospective study of a risk-adapted modification of the conventional management of vasa praevia.

MATERIAL AND METHODS

We analysed 11 years of records involving 18 cases of antenatally diagnosed vasa praevia at our perinatal centre. Each case was managed by a risk-adapted modification of the conventional treatment where both, the steroid administration and the timing of delivery, were dependent on the patient history and clinical signs for preterm birth.

RESULTS

There were no lethal fetal, neonatal, or maternal complications. The earliest caesarean section took place at 34 weeks 1 day, the latest at 37 weeks 1 day, and in more than half of the cases at ≥ 36 weeks.

CONCLUSION

Steroid application is generally recommended for pregnancies before 34 weeks carrying a risk for preterm birth. Thus, retrospectively, none of our cases required steroid administration. This supports our protocol of not obligatorily administering steroids. Delaying the caesarean section up to two weeks beyond the conventionally recommended date of 35 weeks in 78% of our cases resulted in no complications. This justifies the suitability of determining the timing of delivery based on our individual patient assessment. In conclusion, the following recommendations for a risk-adapted management of vasa praevia can be made: 1. weekly evaluation of risk factors for preterm delivery; 2. steroid administration only at risk for preterm birth; 3. admission to hospital with full obstetric and neonatal care facilities between 32 and 34 weeks; 4. elective caesarean section between 35 and 37 weeks, risk-adapted.

[Vasa previa: Of the diagnosis to neonatal prognosis]

Vasa previa is a rare complication of pregnancy (1/2000 to 1/6000) with a high fetal mortality rate (75 to 100%). We will discuss two case reports of vasa previa: the first was diagnosed before labor, while the second was during delivery. In the first case, the diagnosis of vasa previa was confirmed by a transvaginal ultrasound and color doppler, while the second case involved late diagnosis during delivery and after gross examination of the placenta. Risk factors for vasa previa are: low-lying placenta, bilobed or succenturiate lobed placenta, velamentous and in vitro fertilization (IVF). Antenatal diagnosis of vasa previa is crucial because it allows for prophylactic caesarean section and prevents severe Benckiser's hemorrhage responsible for a very high neonatal mortality.