A bilobed placenta also referred to as bipartite placenta, is a variation in placental morphology and refers to a placenta separated into two near equal-sized lobes. If more than two lobes are present, it is termed a trilobed, four-lobed and so on. If the second lobe is smaller than the main lobe (with the umbilical cord insertion), then the smaller lobe is termed a succenturiate lobe.
The estimated incidence is at up to ~4% of pregnancies.
It is thought to result from localized placental atrophy as a result of poor dedicualisation or vascularization of a part of the uterus (dynamic placentation theory) 5.
May be sonographically seen as two separate placental discs of nearly equal size. The cord usually attaches to a thin connecting rim of chorionic tissue which bridges the two lobes. Less commonly the cord may insert into one of the lobes.
- it carries an increased incidence of type II vasa previa
- it may increase the incidence of postpartum hemorrhage due to retained placental tissue
If more than one lobe of the placenta is seen in an antenatal scan consider:
- 1. Fadl S, Moshiri M, Fligner CL, Katz DS, Dighe M. Placental Imaging: Normal Appearance with Review of Pathologic Findings. Radiographics : a review publication of the Radiological Society of North America, Inc. 37 (3): 979-998. doi:10.1148/rg.2017160155 - Pubmed
- 2. Kikuchi A, Uemura R, Serikawa T et-al. Clinical significances of magnetic resonance imaging in prenatal diagnosis of vasa previa in a woman with bilobed placentas. J. Obstet. Gynaecol. Res. 2011;37 (1): 75-8. doi:10.1111/j.1447-0756.2010.01308.x - Pubmed citation
- 3. Benirschke K, Kaufmann P. Pathology of the human placenta. Springer Verlag. (2000) ISBN:0387988947. Read it at Google Books - Find it at Amazon
- 4. Fujikura T, Benson RC, Driscoll SG. The bipartite placenta and its clinical features. Am. J. Obstet. Gynecol. 1970;107 (7): 1013-7. - Pubmed citation
- 5. Baergen RN, Benirschke K(. Manual of Pathology of the Human Placenta. Springer Verlag. (2010) ISBN:1441974938. Read it at Google Books - Find it at Amazon