What the experts have to say about Vasa Previa

Vasa previa is a rare condition; however it is often a lethal one. For years we have tried to get the general ObGyn community to appreciate this condition and to realize that it can result in the death of an otherwise totally normal infant. The tragedy is even greater because the pregnancy is often entirely uncomplicated, and demise of the baby occurs just at the very end of pregnancy when the parents are looking forward with excitement and expectation to the birth of a healthy baby. Our attempts to have more frequent screening performed have been criticized because it is felt that the condition is rare, and indeed it is.  However, very few other conditions carry such a high mortality in a previously normal fetus. The arguments have been that it is prohibitively expensive to screen for vasa previa using ultrasound and that it requires a reasonable degree of skill to make the diagnosis. As such, it is not currently the standard of care to look for vasa previa. Nevertheless, we have identified a second-trimester low-lying placenta as an important risk factor, and recommend targeted sonographic screening with transvaginal sonography and color Doppler for vasa previa in women whose placentas have been identified as low-lying in the second trimester, regardless of whether the placenta remains low-lying at term or not. Other women who should be screened for vasa previa include those with placentas which have succenturiate lobes, women with multiple pregnancies, and those with pregnancies resulting from in-vitro fertlization. Because survival of the baby depends almost entirely on prenatal diagnosis, this strategy for selective screening, followed by elective cesarean delivery, will help reduce the mortality from vasa previa..
Yinka Oyelese, M.D
Georgetown University Hospital, Washington, D.C.
October 2001

Vasa previa is a very rare but well known and well respected condition in the area in which I practice, obstetrics.  The advances in ultrasound have greatly aided in the diagnosis and management of this problem.  The biggest problem is to identify the patients that are at risk for this condition.  The way that we discover these rare abnormalities of  placentation is through routine screening ultrasounds at 18-20 weeks.  If there are low lying placentas or placenta previas, we then examine the lower uterine segment with doppler flow.  We then routinely send these patients to an ultrasound center for confirmation.  Also, any patients with abnormal bleeding in the 2nd and 3rd trimesters need appropriate evaluation for this condition.  The fetal mortality rate if undetected varies considerably from 33%-66%.  The fetal mortality rate when an elective c-section is performed when fetal lung maturity is adequate is very low.
Frank A. Frenduto, M.D.
Private Practice OBGYN, Durham, North Carolina
October 2001 

I believe it is really important to heighten the awareness of physicians and sonographers doing obstetrical ultrasound to the potential clues to this dangerous condition. I also believe vasa previa is more common than currently believed. In my practice alone, I have diagnosed five patients with vasa previa in the last year.  I urge my students to look for the clues of vasa previa. If a placenta is bilobed, regardless of location, or if there are unusual blood vessels at the placental periphery which could be a clue to a membranous umbilical cord origin, then scans using colorflow imaging over the internal os (entrance) of the cervix should be done to exclude vasa previa.
Harris Finberg, M.D.
High-risk obstetrical radiologist in Phoenix
November 2000

Of course I support your goal for vasa praevia. Unfortunately, I fear that this is a problem that will continue to evade even the most vigilant of sonographers unless they actively look for vasa praevia.  Additionally, I am lucky that all the ultrasound machines in my unit have colour Doppler. Unfortunately, this is not the case in many hospitals world wide, making the detection of vasa praevia even more difficult.
Basky Thilaganathan
Director, Fetal Medicine Unit
St.George's Hospital Medical School London  June 2001