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Vasa previa is associated with an increased perinatal mortality rate and rarely is diagnosed in the antepartum period. We present a case in which vasa previa was correctly diagnosed by use of color flow Doppler imaging. This modality is a valuable adjunct in the evaluation of patients suspected to have vasa previa.
Vasa previa was suspected when sudden bleeding occurred in a twin pregnancy during an attempt to attach a scalp electrode. Shortly thereafter, we observed sustained fetal bradycardia using a portable ultrasound. Delivery was accomplished immediately with cesarean section, and an exsanguinated twin A and a normal twin B were delivered. After appropriate resuscitation and transfusion, twin A recovered, and both neonates appear normal at the age of 6 months. According to our review of the literature, this is the first reported case in which both twins survived vasa previa complicated by ruptured membranes.
Vasa previa, though rare (1 in 3000 births), has a significantly high mortality rate. Diagnosis is usually difficult, especially during the antenatal period. However, the use of transvaginal color Doppler ultrasound has increased the recognition of this condition during the antenatal period. Transvaginal color Doppler ultrasound is a more accurate way to view the vulnerable vessels in the area of question. This diagnostic tool will assist in the management of the patient to prevent possible disaster. In this report, transvaginal color Doppler ultrasound helped to recognize and follow up a patient with vasa previa to ensure a successful outcome for both the mother and the fetus. As the antenatal diagnosis of the condition increases with the use of transvaginal color Doppler ultrasound, the high mortality rate should decrease. The importance of meticulous evaluation of the placenta during routine obstetric ultrasound scanning is emphasized.
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BACKGROUND: Vasa previa is a rare but potentially dangerous fetal condition that may occur during pregnancy. Ideally, all cases such cases are detected antenatally, but many present as late vaginal hemorrhaging. At the current time, there is no test for fetal hemoglobin (HbF) in general use. METHODS: A modified method of identifying HbF is presented. Five milliliters of 0.14 M NaOH was combined with 50 microl of a mixture of fetal and maternal blood. After 2 min, it was judged if the solution still had a red tone or not. The sensitivity of this method for detecting HbF was assessed. RESULTS: All 15 clinical personnel could identify both 69% and 34% HbF mixed with adult hemoglobin (100% sensitivity), 14 out of 15 could identify 17% HbF (93% sensitivity), and 12 out of 15 could identify a mixture containing 8% HbF (80% sensitivity). CONCLUSION: Our rapid, simple test for HbF was at least as sensitive as slower, more cumbersome alkali denaturation tests in common use. It could prove to be a lifesaving tool in ruling out vasa previa bleeding in cases of unclear late pregnancy hemorrhages.
Placenta previa, placenta accreta, and vasa previa are important causes of bleeding in the second half of pregnancy and in labor. Risk factors for placenta previa include prior cesarean delivery, pregnancy termination, intrauterine surgery, smoking, multifetal gestation, increasing parity, and maternal age. The diagnostic modality of choice for placenta previa is transvaginal ultrasonography, and women with a complete placenta previa should be delivered by cesarean. Small studies suggest that, when the placenta to cervical os distance is greater than 2 cm, women may safely have a vaginal delivery. Regional anesthesia for cesarean delivery in women with placenta previa is safe. Delivery should take place at an institution with adequate blood banking facilities. The incidence of placenta accreta is rising, primarily because of the rise in cesarean delivery rates. This condition can be associated with massive blood loss at delivery. Prenatal diagnosis by imaging, followed by planning of peripartum management by a multidisciplinary team, may help reduce morbidity and mortality. Women known to have placenta accreta should be delivered by cesarean, and no attempt should be made to separate the placenta at the time of delivery. The majority of women with significant degrees of placenta accreta will require a hysterectomy. Although successful conservative management has been described, there are currently insufficient data to recommend this approach to management routinely. Vasa previa carries a risk of fetal exsanguination and death when the membranes rupture. The condition can be diagnosed prenatally by ultrasound examination. Good outcomes depend on prenatal diagnosis and cesarean delivery before the membranes rupture.
Diagnosis of vasa previa requires a high index of suspicion. Vasa previa must be included in the differential diagnosis of all cases of third trimester bleeding. When pulsatile vessels are palpated preceding the fetal vertex, vasa previa should be considered along with cord prolapse. Early diagnosis and intervention result in a favorable fetal outcome in this rare condition.
INTRODUCTION: Vasa previa is an uncommon obstetrical complication that poses a high risk of fetal demise if not recognized before rupture of membranes. It is vital that providers recognize risk factors for vasa previa and diagnose this condition before the onset of labor so that fetal shock or demise is prevented. METHODS: We report a patient with a bilobed placenta and perinatal hemorrhage caused by vasa previa that was not detected with antepartum ultrasound. A review of the literature published between January 1965 and August 2002 was conducted using a MEDLINE-assisted search using the key words "vasa previa," "bilobed placenta," and "succenturiate." RESULTS: Risk factors for vasa previa have been identified. Advances in ultrasound have led to improved ability to diagnose this condition. Evaluation of patients in high-risk groups with transvaginal color flow Doppler ultrasound should be considered. The accuracy of this technique for diagnosing vasa previa is not known, nor is the true incidence of this condition. Antepartum diagnosis is associated with improved outcomes but does not eliminate morbidity and mortality. CONCLUSIONS: A high index of suspicion for vasa previa at the time of amniotomy is required, because all cases cannot be diagnosed before the onset of labor.
OBJECTIVE: To evaluate whether vasa previa at delivery is associated with a history of second-trimester placenta previa. STUDY DESIGN: Retrospective, case-control study of all vasa previa cases at Good Samaritan Regional Medical Center from January 1, 1991, to May 1, 2001. Cases were identified by ICD-9 codes and confirmed by chart review. Each case was matched in a 1:4 ratio with controls based upon normal placentation at delivery, ultrasound documentation of midtrimester placental location, maternal parity and gestational age at delivery. RESULTS: During the study period, 13 cases of vasa previa were identified. Nine cases (9/13, 69.2%) of vasa previa at delivery had a second-trimester placenta previa as documented by midtrimester ultrasonography, whereas 2 controls (2/52, 3.8%) had a second-trimester placenta previa (P < .000001, OR = 56.3, 95% CI = 8.9-354.1). CONCLUSION: There is a highly significant association between vasa previa at delivery and a history of second-trimester placenta previa.
Vasa previa is a rare cause of antepartum hemorrhage, with a fetal mortality between 33% and 100%. We treated a patient in whom the diagnosis could not be made with certainty antepartum. The pregnancy out-come of seven cases of velamentous insertion, including three of vasa previa, was reviewed. Our results compared with those reported in the literature. Fetal mortality and morbidity from vasa previa can be reduced if there is a high index of suspicion, a reliable method of diagnosis and prompt surgical intervention.
UNLABELLED: Vasa previa is a rarely reported condition in which the fetal blood vessels, unsupported by either the umbilical cord or placental tissue, traverse the fetal membranes of the lower segment of the uterus below the presenting part. The condition has a high fetal mortality due to fetal exsanguination resulting from fetal vessels tearing when the membranes rupture. Despite improvements in medical technology, vasa previa often remains unsuspected until this fatal fetal vessel rupture occurs. Significant reduction in the fetal mortality from this condition depends on a high index of suspicion leading to antenatal diagnosis, and elective delivery by cesarean. We believe transvaginal ultrasound in combination with color Doppler is the most effective tool in the antenatal diagnosis of vasa previa and should be utilized in patients at risk, specifically those with bilobed, succenturiate-lobed, and low-lying placentas, pregnancies resulting from in vitro fertilization, and multiple pregnancy. Where there has been antepartum or intrapartum hemorrhage, especially when associated with fetal heart irregularities, we also recommend a test to exclude fetal blood in the vaginal blood. Similarly, amnioscopy before amniotomy may help to diagnose this condition. Cesarean delivery is the method of delivery of choice, and aggressive resuscitation of the affected neonate may be life saving. With a high index of suspicion, antenatal diagnosis using transvaginal sonography in combination with color Doppler, elective delivery by cesarean, and aggressive resuscitation of the neonate where fetal vessel rupture has occurred, the mortality from this complication may be considerably reduced. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader will be able to identify the risk factors and associated conditions for vasa previa, to identify the various clinical presentations and management of vasa previa, and to be aware of the diagnostic tools available to make the antepartum diagnosis of vasa previa.
OBJECTIVES: In a population of 45 placenta previa observed at third trimester of gestation we have tried to make the prenatal diagnosis of placenta percreta and vasa previa with color and pulsed Doppler ultrasonography. MATERIALS AND METHODS: We used a transabdominal sonography with full bladder and a transvaginal sonography with empty bladder. The first images obtained showed 20 placenta previa over the internal cervical os, 3 marginal and 22 low-lying placenta previa. We tried to find evidence of placenta percreta with gray-scale ultrasonography (loss of normal hypoechoic retroplacental myometrial zone, focal disruption of the uterine serosa and surrounding tissues, presence of intra placental lacunae) and with color and pulsed Doppler (arterial vessels with a diastolic flow value less than the flow value of a spiral artery behind the placenta, arterial vessels crossing from the placenta to surrounding tissues, intraplacental lacunae with arterial flow). We tried to find evidence of vasa previa in color and pulsed Doppler (a fetal vessel in seen above the lower segment of the uterus and below the fetal head. There is no change in the location of the vessel despite positional changes in both mother and fetus). The positivity of one sign in gray-scale ultrasonography or in color and pulsed Doppler led us to believe that the patient was affected by the anomaly. The final diagnosis of abnormal adherence of the placenta and of vasa previa was made on histological examination. RESULTS: Among the 20 placenta previa over the internal cervical os, we found 1 placenta percreta, 1 placenta accreta and 3 cases of vasa previa. In spite of our limited sample of cases of abnormal adherences, our results showed that gray-scale ultrasonography was sufficient to make a prenatal diagnosis of placenta accreta/percreta. Negative predictive value is 100% on a sample of 43 patients with no abnormal placental adherence. Color and pulsed Doppler brought no further evidence. In our population, color and pulsed Doppler had 100% positive predictive value for diagnosis of vasa previa. CONCLUSION: We found the only 2 cases of abnormal adherent placental fragments and the 3 cases of vasa previa present in our population. The study of the lower segment of the uterus should be thorough as abnormal zones may be small-sized. Color Doppler is the reference technique for sighting vasa previa and gray-scale ultrasonography for abnormal adherences of the placenta.
Vasa previa is a cause of sudden unanticipated fetal death, with a fetal mortality of 33-100%. Transvaginal sonography (TVS) and color Doppler may aid in making the diagnosis antenatally, allowing elective Cesarean delivery, thereby avoiding fetal death from exsanguination which would occur if the membranes were allowed to rupture in labor. Whilst it is not feasible to screen all pregnant women for vasa previa, antenatal examination with TVS and color Doppler of women at risk, specifically those with low-lying placentas, bi-lobed, multi-lobed and succenturiate-lobed placentas, multiple pregnancies and pregnancies resulting from in vitro fertilization may lead to antenatal diagnosis of the condition. We present the last three cases of vasa previa to have occurred in our institution, two of which were diagnosed antenatally using TVS and color Doppler. In all three cases, routine 20-week obstetric sonography revealed low-lying placentas; in only one of these did the placenta remain low at term. A low-lying placenta at 20 weeks may be a risk factor for vasa previa; we suggest that further studies be carried out to ascertain this. Judicious use of TVS and color Doppler in women considered at risk of vasa previa may help to reduce the mortality from this condition.
A case of vasa previa in twin pregnancy associated with a sinusoidal heart rate was observed. A review of the world literature revealed eight previously reported cases of vasa previa in twins. No first twin survived, and 62.5% of second twins eventually died from partial or complete exsanguination. This is the first reported case of sinusoidal fetal heart rate in association with vasa previa. Continuous fetal monitoring suggested the diagnosis of funic presentation and of fetal bleeding. A high index of suspicion, use of amnioscopy, ability to detect fetal blood in the vaginal pool, continuous fetal heart rate monitoring and ultrasonography may help in reducing the high perinatal mortality associated with vasa previa.
We report the prenatal diagnosis of vasa previa using transvaginal sonography and color Doppler. This case supports the previously reported association of vasa previa with second trimester low-lying placentas and in-vitro fertilization. Sonographic examination for vasa previa should be considered in pregnancies with low-lying placentas and those resulting from in-vitro fertilization.
An antepartum diagnosis of vasa previa was considered in a patient in whom ultrasound revealed pulsatile loops of cord overlying the cervical os. This diagnosis was confirmed at the time of cesarean delivery. We offer a literature review of vasa previa and make recommendations for using ultrasonography to diagnose vasa previa.
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