Description

G2P1L1 24 yr pregnant lady 37 wks POG delivered a LBW (Birth wt - 2.3 kg) female baby vaginally with uneventful labour. Incidental finding of large surface placental cyst (7 x 5 cm) observed which was missed on sonography.

A placental cyst is a small area in the placenta containing liquified clear material, usually as a result of the breakdown of a material called fibrin in the placenta. On ultrasound, it appears as a dark area in the placenta sometimes surrounded by a bright white border. Areas that measure less than 1 cm across are common, and are associated with normal pregnancy outcome [1]. Placental cysts may be located within the placental tissue (septal cysts) or under the foetal plate (subchorionic cysts). The incidence of these placental cysts has been reported to be 5% to 7% for subchorionic cysts and up to 20% for septal cysts [2]. On macroscopic examination, they are usually singular, but can be multiple. They may be central and lie immediately below the chorionic plate. Cysts over 5 cm may be related to blood flow problems in the placenta & if attached near the umbilical cord insertion should be followed closely by ultrasound, colour Doppler sonography, and assessment of foetal well-being to rule out partial occlusion of umbilical cord blood flow and possible intrauterine growth retardation [3].

Figure 1: Large placental cyst (Gross- Clear fluid filled).

References

1. Brown DL, DiSalvo DN, Frates MC, Davidson KM, Genest DR. Placental surface cysts detected on sonography: histologic and clinical correlation. J Ultrasound Med. 2002; 21(6): 641-6; quiz 647-8. doi: 10.7863/jum.2002.21.6.641.
2. Benirschke K, Kaufmann R. Pathology of the Human Placenta. 2nd ed. New York, NY: Springer-Verlag. 1990.
3. Kirkinen P, Jouppila P. Intrauterine membranous cyst: A report of antenatal diagnosis and obstetrics aspects in two cases. Obstet Gynecol. 1 986; 67: 26S-30S.