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
Placental Infection
Infections in the placenta develop by two pathways: (1) ascending infection through the birth canal and (2) hematogenous (transplacental) infection.
Ascending infections are by far the most common and are virtually always bacterial; in many such instances, localized infection of the membranes produces premature rupture of membranes and preterm delivery. The amniotic fluid may be cloudy with purulent exudate, and histologically the chorion-amnion contains an infiltrate of neutrophils accompanied by edema and congestion of the vessels.The infection frequently elicits a fetal response consisting of a “vasculitis” of the umbilical and fetal chorionic plate vessels.
Uncommonly, bacterial infections may result from hematogenous spread to the placenta, leading to acute villitis .
Pre-eclampsia.
systemic syndrome - widespread maternal endothelial dysfunction that presents during pregnancy with htn, edema and proteinuria
usually in last trimester
more common in primiparas
some seriously ill, convulsions = eclampsia
other complications: hypercoagulability, acute renal failure, pulmonary edema.
typically insidious onset
headaches and visual disturbances- indicative
complete hydatidiform mole
large avascular villi with trophoblastic proliferation
occurs when a fertilized ovum contains only paternal chromosomes (usually 46, XX), produces marked uterine enlargement, “snowstorm” effect with no fetus on ultrasonography, some give rise to choriocarcinoma.
partial hydatidiform mole
some villi are enlarged, with minimal trophoblast proliferation
typically are triploid (69, XXX or 69 XXY or 69XYY), a malformed fetus is present that rarely goes to term, rarely gives rise to choriocarcinoma.
choriocarcinoma
a malignant proliferation of syncytiotrophoblast with no villi, often hemorrhagic, no fetus present
HCG levels are often extremely high, can metastasize, many are sensitive to chemotherapy
placental site trophoblastic tumor
rare localized proliferation of intermediate trophoblast that can produce a grossly visilbe nodule
most are benign, rare malignant cases
placental site nodule or plaque
a rare proliferation of intermediate trophoblast that is microscopic.
of no major consequence
