Gestational and placental path Flashcards
placenta histology
First trimester- chorionic villi- delicate mesh of central stroma surrounded by 2 discrete layers of epithelium- syncytiotrophoblasts and inner layer of cytotrophoblasts
third trimester chorionic villi - stroma with dense netwrok of dilated capillaries surrounded by markedly thinned-out -trophoblast layers
Spontaneous abortion
pregnancy loss before 20 weeks of gestation. Most of these occur before 12 weeks. Ten to fifteen percent of clinically recognized pregnancies terminate in spontaneous abortion, mostly for unknown reasons.
Fetal chromosomal anomalies
, such as aneuploidy, polyploidy, and translocations, are present in approximately 50% of early abortuses. More subtle genetic defects, for which routine genetic testing is not readily available, account for an additional fraction of abortions.
•Maternal endocrine factors, including luteal-phase defect, poorly controlled diabetes, and other uncorrected endocrine disorders
Physical defects of the uterus, such as submucosal leiomyomas, uterine polyps, or uterine malformations, may prevent or disrupt implantation
Systemic disorders affecting the maternal vasculature, such as antiphospholipid antibody syndrome, coagulopathies, and hypertension
Infections with protozoa (Toxoplasma), bacteria (Mycoplasma, Listeria), or a number of viruses. Ascending infection is particularly common in second-trimester losses.
Trisomy 21
Similar facial changes are apparent in 2-month-old infant (note increased ‘Mongoloid’ slant of palpebral fissures). E: Duodenal atresia. Single palmar crease; large primum atrial septal defect, large ventricular septal defect in position of AV canal, and cleft septal leaflet of the tricuspid valve can also be present in Trisomy 21.
Ectopic pregnancy
implantation of the fetus in a site other than the normal intrauterine location; the most common site is the extrauterine fallopian tube (approximately 90% of cases).
Other sites: the ovary, the abdominal cavity, and the intrauterine portion of the fallopian tube (cornual pregnancy).
- 2% of confirmed pregnancies.
- The most important predisposing condition: prior pelvic inflammatory disease resulting in intralumenal fallopian tube scarring (chronic salpingitis).
- risk of ectopic pregnancy is also increased with peritubal scarring and adhesions, which may be caused by appendicitis, endometriosis, and previous surgery. In some cases, however, the fallopian tubes are apparently normal. Use of an intrauterine contraceptive device is associated with twofold increase of ectopic pregnancy.
Rupture of a tubal pregnancy
medical emergency. The clinical course of ectopic tubal pregnancy is characterized by the onset of moderate to severe abdominal pain and vaginal bleeding 6 to 8 weeks after last menstrual period, correlating with distention and then rupture of the fallopian tube. In such cases the patient may rapidly develop hemorrhagic shock with signs of an acute abdomen, and therefore early diagnosis is critical. Diagnosis is based on determination of chorionic gonadotropin titers, pelvic sonography, endometrial biopsy (which shows decidua without chorionic villi or implantation site) and/or laparoscopy. Despite advances in early diagnosis, ectopic pregnancy still accounts for 4% to 10% of pregnancy-related deaths.
Twin pregnancies
arise from fertilization of 2 ova (dizygotic) or from division of one fertilized ovum (monozygotic)
3 types of twin placentas: diamnionic dichorionic (may be fused)
diamnionic monochorionic, and monoamnionic monochorionic.
Monochorionic placentas imply monozygotic (identical) twins) and the time at which splitting of the developing embryo occurs determines whether one or two amnions are present.
dichorionic placentation may occur with either monozygotic or dizygotic twins and is not specific.
complication of monochorionic twin pregnancy
twin-twin transfusion syndrome. placentas have vascular anastomoses that connect hte circulations of the twins, and in some cases these connections include one or more arteriovenous shunts. If these shunts preferentially increase blood flow to one twin at the expense of the second, one twin will be underperfused, while the second will be fluid overloaded. It is this phenomenon that constitutes the twin-twin transfusion syndrome, which if severe may result in the death of one or both fetuses.
Abnormalities of placental implantation
placenta previa
placenta accreta
placenta previa
implants in lower uterine segment or cerfix, often –> serious third-trimester bleeding.
complete placenta previa covers the internal cervical os and requires C-section to avert placental rupture and fatal maternal hemorrhage during vaginal delivery.
placenta accreta
partial or complete absence of the decidua, such that the placental villous tissue adheres directly to the myometrium, whcih leads to a failure of placental separation at birth. Important cause of severe, life-threateneing post-partum bleeding.
common predisposing factors- placenta previa and history of c-section.
Placenta Previa presents
with painless bleeding during the third trimester
types of placenta previa
complete previa- when the cervical os, the mouth of the uterus, is completely covereed
partial previa- just a portion of the cervix is covered by the placenta
marginal previa- extends just to the edge of the cervix
Placenta accreta happens when
all of the placenta or a part of it is abnormally attached to the myometrium. Based on the normally anatomy of the placenta, it is always attached to the wall of the uterus; but in placenta accreta, its blood vessels and other parts are growing too deeply into the wall of the uterus.
Complications of twinning
Low birth weight IUGR Fetal demise or loss Gestational diabetes Placental Abruptio Gestational Diabetes
