Sites of implantation of embryo

1. Sites of implantation of embryo and pregnancy with placental abnormalities

2. Sites of implantation of embryo

3. introduction Implantation begins first with attachment (adplantation) of the blastocyst through the outer trophblast cells to the uterine lining. Following adplantation, trophoblastic cells on the outside differentiate into syncitiotrophoblasts which invade the uterine endometrium. The blastocyst then moves into the endometrium, initially partially buried, and on completion of implantation, is fully buried in the endometrium. The site of implantation is marked on the surface by a "plug". Normal pregnancy

4. Normal site of implantation the blastocyst makes contact with the lining of the uterus - the endometrium. This has prepared for such a possibility by thickening, becoming more glandular, and developing a rich blood supply. The blastocyst begins to implant, a process that will take several days

5. Abnormal Implantations in uterus Placenta praevia : the placenta is attached to the uterine wall close to or covering the cervix. It causes difficulty during childbirth and may cause severe bleeding. Various types of placenta praevia may be recognized as given below: Type I or low lying: The placenta sits in the lower segment of the uterus but does not touch the cervix Type II or marginal: The placenta touches, but does not cover, the top of the cervix. Type III or partial: The placenta partially covers the top of the cervix Type IV or complete: The placenta completely covers the top of the cervix (placenta preavia)

6. Placenta acceta , increta , percreta Placenta accreta Accounts for 75-78% Placenta attached directly to the muscles of the uterine wall Placenta increta Accounts for 17% of cases Placenta extends into the uterine muscles Placenta percreta 5-7% which extends through the entire wall of the uterus

7. Implantation outside the uterus

8. Tubal pregnancy Ectopic pregnancy often occurs if zona pellucida is lost too early allowing premature implantation Tubal pregnancy 94% embryo may develop through early stages. can erode through the uterine horn reattach within the peritoneal cavity Most common sites of ectopic pregnancy external surface of uterus bowel gastrointestinal tract, mesentry peritoneal wall If not spontaneous then, embryo has to be removed surgically Tubal pregnancy after hesterectomy

9. Ectopic pregnancy An ectopic pregnancy, or eccysis , is a complication of pregnancy in which the embryo implants outside the uterine cavity . With rare exceptions, ectopic pregnancies are not viable. Furthermore, they are dangerous for the parent, since internal haemorrhage is a life threatening complication. Most ectopic pregnancies occur in the Fallopian tube (so-called tubal pregnancies), but implantation can also occur in the cervix, ovaries, and abdomen. In a typical ectopic pregnancy, the embryo adheres to the lining of the fallopian tube and burrows into the tubal lining. Most commonly this invades vessels and will cause bleeding.

10. Ectopic pregnancy Ectopic pregnancies can be classified into 4 categories Tubal pregnancy Non-tubal ectopic pregnancy Heterotopic pregnancy Persistent ectopic pregnancy

11. Tubal pregnancy The vast majority of ectopic pregnancies implant in the Fallopian tube. Pregnancies can grow in the fimbrial end (5 %), ampullary section (80 %), isthmus (12%), cornual and interstitial part of the tube (2 %). 7 week embryo in open oviduct

12. Non tubal pregnancy Two per cent of ectopic pregnancies occur are intraabdominal. Very rarely, a live baby has been delivered from an abdominal pregnancy. In such a situation the placenta sits on the intraabdominal organs or the peritoneum and has found sufficient blood supply. This is generally bowel or mesentery, but other sites, such as the (kidney), liver or hepatic artery or even aorta have been seen. Any attempts to remove the placenta from the organs to which it is attached usually lead to uncontrollable bleeding from the attachment site.

13. Interstitial pregnancy An interstitial pregnancy is a uterine but ectopic pregnancy; the pregnancy is located in that part of the Fallopian tube that penetrates the muscular layer of the uterus . Interstitial pregnancies account for 2–4% of all tubal pregnancies. About one in fifty women with an interstitial pregnancy die. Patients with an interstitial pregnancies have a 7-times higher mortality than those with ectopics in general . With the growing use of assisted reproductive technologies, the incidence of interstitial pregnancy is rising

14. Persistent ectopic pregnancy A persistent ectopic pregnancy refers to the continuation of trophoblastic growth after a surgical intervention to remove an ectopic pregnancy. After a conservative procedure that attempts to preserve the affected fallopian tube such as a salpingotomy , in about 15-20% the major portion of the ectopic growth may have been removed, but some trophoblastic tissue, perhaps deeply embedded, has escaped removal and continues to grow

15. Patients with an ectopic pregnancy are generally at higher risk for a recurrence, however, there are no specific data for patients with an interstitial pregnancy. When a new pregnancy is diagnosed it is important to monitor the pregnancy by transvaginal solography to assure that is it properly located, and that the surgically repaired area remains intact . Caesarean delivery is recommended to avoid uterine rupture during labour.

16. Placental abnormalities

17. Placenta introduction A placenta is an organ that connects the developing foetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply Normal placenta- diameter = 22cm thickness = (2.0~2.5)cm

18. PLACENTAL ABNORMALITIES Abnormalities of placenta can be classified into three broad categories; Abnormal shape Abnormal implantation Degenerative placental lesions

19. Abnormalities based on shape and implantation Placenta bipartita or bilobata the placenta is separated into lobes. division is incomplete and the vessels of foetal origin extend from one lobe to the other before uniting to form the umbilical cord Placenta duplex, triplex two or three distinct lobes are visible entirely and the vessels remain distinct.

20. Succenturiate lobes small accessory lobe ≥1, develop in the membranes at a distant from the periphery of the main placenta, to which they usually have vascular connections of foetal origin incidence : 5% retained in the uterus after delivery and may cause serious haemorrhage accompanying vasa previa - dangerous foetal haemorrhage at delivery

21. Membranaceous Placenta all of the foetal membranes are covered by functioning villi and the placenta develops as a thin membranous structure occupying the entire periphery of the chorion serious haemorrhage d/t associated placenta previa or accreta

22. Abnormality Definition Clinical significance Extrachorial Placentation Circumvallate Placenta Circummarginate placenta When the chorionic plate, which is on the fetal side of the placenta, is smaller than the basal plate, which is located on the maternal side, the placental periphery is uncovered Fetal surface of such a placenta presents a central depression surrounded by a thickened, grayish-white ring. Ring : composed of a double fold of amnion and chorion with degenerated decidua and fibrin in between Within the ring, the fetal surface presents the usual appearance, except that the large vessels terminate abruptly at the margin of the ring Ring does not have the central depression with the fold of membranes Antepartum hemorrhage - from placental abruption and fetal hemorrhage Preterm delivery Perinatal mortality Fetal malformations less well defined

23. Abnormalities based on degenerative lesions Causes : trophoblast aging or impairment of uteroplacental circulation with infarction Deposition of calcium salts is heaviest on the maternal surface in the basal plate. → further deposition occurs along the septa and both increase as pregnancy progresses Calcification : 10 - 15% of all placentas at term some degree of calcification ≥ ½ of placentas

24. Calcified placenta Specimen of a calcified(white regions) placenta Sonography of another calcified placenta

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