*Vrije Universiteit Brussel  and ^&Women’s Health Alliance, Nashville TN

Placenta membranacea or placenta diffusa is a rare abnormality in which all or most fetal membranes remain covered by chorionic villi, because the chorion has failed to differentiate into chorion leave and chorion frondosum [1] .

Sonographic examination demonstrates a placenta that is covering most or the entire uterine wall [3] . The earliest reports were made in 1973 and 1976  by the group of Stuart Campbell [4] and Yuri Wladimiroff [5]

This condition is often associated with placenta accreta [6] , increta, percreta and vasa previa.

These pregnancies are complicated by recurrent antepartum hemorrhages [7] , second trimester miscarriages, preterm delivery, intra-uterine growth restriction and fetal demise [8] . Delivery is often complicated with post-partum hemorrhage and placental retention. In several cases it was necessary to perform a hysterectomy immediately post-partum¹ .

Vasa  previa is a rare complication of pregnancy (1 in 3000 deliveries) [9]   associated with a high fetal morbidity and mortality [10] .

The umbilical cord crosses the internal os in front of the presenting part, usually the fetal head. It occurs primarily in two conditions: a velamentous insertion of the umbilical cord or in case of placenta succenturiate with a lobe on the opposite site of the internal os from the main placenta [11] .

The clinical picture consists of rupture of the umbilical cord during labor if the head descent or during rupture of the membranes, resulting in a fetal hemorrhage with rapid fetal compromise responsible for fetal death from acute exsanguinations in 75%-100% [12] .

Several studies have reported the importance of using color or power Doppler ultrasound for the prenatal diagnosis of vasa previa^{9 -10 ,12 , [13] , [14]} . Vascular flow and Doppler patterns characteristic of the umbilical cord can be demonstrated in structures near the internal os and as such demonstrate vasa previa.

There are 2 video clips one of the placenta membranacea (5.3 MB) and one of the vasa previa (2.8 MB)

References

[2] Greenberg JA, Sorem KA, Shifren JL, Riley LE Placenta membranacea with placenta increta: a case report and literature review. Obstet Gynecol 1991 Sep;78(3 Pt 2):512-4

[3] Molloy CE, McDowell W, Armour T, Crawford W, Bernstine R Ultrasonic diagnosis of placenta membranacea in utero. J Ultrasound Med 1983 Aug;2(8):377-9

[4] Pryse-Davies J, Dewhurst CJ, Campbell S Placenta membranacea. J Obstet Gynaecol Br Commonw 1973 Dec;80(12):1106-10

[5] Wladimiroff JW, Wallenburg HC, vanden Putten P, Drogendijk AC Ultrasonic diagnosis of placenta membranacea. Arch Gynakol 1976 Sep 17;221(2):167-74

[6] Dinh TV, Bedi DG, Salinas J Placenta membranacea, previa and accreta. A case report. J Reprod Med 1992 Jan;37(1):97-9

[7] Heras JL, Harding PG, Haust MD Recurrent bleeding associated with placenta membranacea partialis: report of a case. Am J Obstet Gynecol 1982 Oct 15;144(4):480-2

[8] Wilkins BS, Batcup G, Vinall PS Partial placenta membranacea. Br J Obstet Gynaecol 1991 Jul;98(7):675-9

[9] K.H. Chen, P.  Konchak. Use of transvaginal color Doppler ultrasound to diagnose vasa previa. J Am Osteopath Assoc 1998;98(2):116-7

[10] A.A. Baschat, U. Gembruch. Ante- and intrapartum diagnosis of vasa previa in singleton pregnancies by colour coded Doppler sonography. Eur J Obstet Gynecol Reprod Biol 1998;79:19-25

[11] Callen. Ultrasonography in obstetrics and gynecology. 4^th edition: Ultrasound of the placenta and umbilical cord.

[12] S. Heckel et al. Benckiser’s hemorrhage. Two case reports and a review of the literature. J Gynecol Obstet Biol Reprod 1993;22:184-90

[13] A.D. Fleming et al. Diagnosis of vasa previa with ultrasound and color flow Doppler: a case report. Nebr. Med. 1996;81:191-3

[14] L.H. Nelson et al. Diagnosis of vasa previa with transvaginal and color Doppler ultrasound. Obstet Gynecol 1990;76:205-9