CIRCUMVALLATE PLACENTA

A thickened membranous rim, composed of a double fold of amnion and chorion, with degenerated decidua and fibrin in between, is folded inward toward the center. The placenta forms a central depression surrounded by a thickened, yellow-white ring some distance from the periphery. There is a controversy in the literature regarding the incidence and clinical significance of circumvallate placenta. Reported ranges from 1-18%, depending on whether partial anomalies are included (1-4). 

ETIOLOGY

Circumvallate placenta is thought to result from deep implantation of the placenta into the decidua. Because of this excessive implantation, the placenta covers more than half of the fetal sac. The placenta reduces this excessive covering to the normal one-fourth by separating from the uterine wall, with the resultant back folding of the placenta and fetal membranes towards the chorionic surface (5).

• Incidental finding with no associated complications (2).
• Increased incidence in multigravida (2,3).
• Increased incidence if the patient has had a previous circumvallate placenta (2,3).

CLINICALLY

• Bleeding (usually painless) in up to 50% of cases (3,4).
• Hydrorrhea (27%) (3,4).
• Severe intermittent uterine contractions (20%) (3,4).

ULTRASOUND

Link to Ultrasound

COMPLICATIONS

Link to Complications

SONOGRAPHIC APPROACH TO INTRAUTERINE BANDS

AND MEMBRANES

Sonographic approach to intrauterine bands and membranes

OUTCOME

• Incidental finding with normal outcome (2).
• Increased perinatal mortality (1,3), prematurity (1,3), antepartum bleeding (1.4), abruptio placenta(1,4), and abortion (3,4).

REFERENCES

1. Benson RC, Fujikura T. Circumvallate and circummarginate placenta: Unimportant clinical entities. Obstet Gynecol 1969;34:799.
2. Wentworth P. Circumvallate and circummarginate placentas: Their incidence and clinical significance. Am J Obstet Gynecol 1968;102:44.
3. Wilson D, Paalman RJ. Clinical significance of circumvallate placenta. Obstet Gynecol 1967;29:774.
4. Naftolin F, Khudr G, Benirschke K et.al. The syndrome of chronic abruptio placenta, hydrorrhea, and circumvallate placenta. Am J Obstet Gynecol 1973;116:347.
5. Bey M, Dott A, Miller JM. The sonographic diagnosis of circumvallate placenta. Obstetrics and Gynecology 1991;78(3):515-516.