Placenta at term for nursing students

placenta at term in obs for nursing students

1. PLACENTA AT TERM B y Nitika Msc Obstetrics & Gynaecological

2. INTRODUCTION The human placenta is discoid, haemochorial and deciduate The placenta is attached to the uterine wall and establishes connection between the mother and fetus through the umbilical cord

3. PLACENTA AT TERM Gross Anatomy : The placenta at term is: a circular disc with diameter of 15-20cm thickness : 2.5cm Thin off towards the edge Feels spongy weighs: 500gm

4. Choronic plate Decidua basalis Intervillious space Amniotic Membrane Tertiary stem villi Syncytiotrophoblast Cyt o trophoblast Chorion laeve Decidua parietalis & capsularis fused

5. It presents two surface fetal & maternal peripheral margin surface surface

6. Fetal surface: Covered by smooth and glistening amnion with the umbilical cord attached at or near its centre At term about four fifth of the placenta is of fetal origin

7. Maternal surface : Rough and spongy Maternal blood gives it a dull red color Thin greyish layer: remnant of decidua basalis Is mapped out into 15-20 lobes or cotyledons

8. Numerous small greyish spots are visible: due deposition of calcium in the degenerated areas Only decidua basalis and the blood in the intervillious space are of maternal origin

9. PERIPHERAL MARGIN It is limited by the fused basal and chorionic plates and is continuous with the chorion laeve and amnion. Essentially, the chorion and the placenta are one structure but the placenta is specialised part of the chorion

10. Attachment: Attached to the upper part of body of the uterus encroaching to the fundus adjacent to the anterior or posterior wall The attachment to the uterine wall is effective due to the anchoring villi

11. Separation Placenta separates after the birth of the baby and the line of separation is through the decidua spongiosum

12. Amnion : It consists of single layer of cubical epithelium loosely attached to the adjacent chorionic plate. It takes no part in formation of the placenta

13. Helps in formation of amniotic fluid. Facilitate dilation of the cervix during labour. Rich source of glycerophospholipids containing arachidonic acid precursor of prostaglandin.

14. CHORION It is thicker than amnion friable and shaggy on both side. Internally it is attached to the amnion by loose areolar tissue and remnant of primitive mesenchyme. Externally it is covered by vestiges of trophoblastic layer and the decidual cells of the fused decidua capsularis and parietalis which can be distinguished microscopically. The term chorion contains no vessels and nerves.

15. The umbilical cord The umbilical cord or funis forms the connecting link between the fetus and the placenta. Characteristics Its about 50 cm in length an usual variation of 30-100cm. Its diameter average 1.5cm with variation of 1 – 2.5cm. cont

16. Its thickness is not uniform but presents nodes or swelling at places, these swelling are false knots may be due to dilatation of the umbilical veins or local collection of Wharton's jelly. It shows a spiral twist from the left to right from as early as 12 th wk due to spiral turn taken by the vessels vein around the arteries.

17. -: placental circulation:- Maternal circulation or utero placental circulation :- The blood is deliverd to the placental bed in the decidua by spiral arteries and flow into the blood spaces surrounding the villi. Its direction of flow is similar to fountain. fetal circulation :-fetal blood low in oxygen is pumped by the fetal heart toward the placenta along the umbilical arteries and transported along their branches to the capillaries of the chorionic villi. yielded up Co2 & absorbed oxygen, the blood is returned to fetus via umbilical vein.

18. BIBLIOGRAPHY Dutta D.C. ‘text book of Obstetrics’, sixth edition,Pp:28 to34 and 218 to 220 Ostrzenski adam ; gynaecology; Lippincott ; Second edition ; pg no - 209-216 ,193 www.sciencedirect.com/science/journal www.en. Wikipedia.org/ wik /placenta www.placentajournal.org/