Saturday, April 3, 2021
Saturday, March 6, 2021
Cervical insufﬁciency is characterized by asymptomatic dilation of the internal os during pregnancy. This generally leads to dilation of the entire cervical canal during the second trimester with subsequent risk of rupture of the membranes and/or expulsion of the fetus. This affects 1/54 to 1/1842 pregnancies (resulting from uncertain diagnostic criteria). Though uncommon, it is thought to be involved with as many as 20% to 25% of all second-trimester pregnancy losses.
Abortion is the loss or failure of an early pregnancy and it is deﬁned in several forms: complete, incomplete, inevitable, missed, septic, and threatened. A complete abortion is the termination of a pregnancy before the age of viability, typically deﬁned as occurring at less than 20 weeks from the ﬁrst day of the last normal menstrual period or involving a fetus of weight less than 500 g. Most complete abortions generally occur before 6 weeks or after 14 weeks of gestation. An incomplete abortion is the spontaneous passage of some, but not all, of the products of conception. A pregnancy in which rupture of the membranes and/or cervical dilation takes place during the ﬁrst half of pregnancy is labeled an inevitable abortion. Uterine contractions typically follow, ending in spontaneous loss of the pregnancy for most patients. A missed abortion is the retention of a failed intrauterine pregnancy for an extended period. A septic abortion is a variant of an incomplete abortion in which infection of the uterus and its contents has occurred. A threatened abortion is a pregnancy that is at risk for some reason. Most often, this applies to any pregnancy in which vaginal bleeding or uterine cramping takes place but no cervical changes have occurred. Estimates for the frequency of complete abortions are as high as 50% to 60% of all conceptions and between 10% and 20% of known pregnancies. Less than 2% of fetal losses are missed abortions. Septic abortions occur in 0.40 to 0.6 of 100,000 spontaneous pregnancy losses. Threatened abortions occur in 30% to 40% of pregnant women.
ECTOPIC PREGNANCY III— INTERSTITIAL, ABDOMINAL, OVARIAN
When, during the process of abortion or rupture, the trophoblast, after total separation, implants itself again somewhere in the peritoneum, as happens on rare occasions, it may grow and develop into a secondary abdominal pregnancy. The embryo in such cases may have remained in its original amniotic sac, or a new sac may have formed from the surrounding tissues. A secondary abdominal pregnancy may also result from a beginning tubal implantation that ruptured and became inserted between the leaves of the broad ligament. If the latter should rupture again, the embryo in the fetal sac may extrude into the peritoneal cavity, with the placenta remaining in the extraperitoneal position between the broad ligament sheets. In still more exceptional cases, the fertilized ovum may escape through the open end of the tube, attaching itself to the parietal or visceral peritoneum or the omentum, developing into a primary abdominal pregnancy. It has even been reported that an abdominal pregnancy has originated from a defect in the uterine wall, which had been ﬁlled and closed up by the omentum during the healing period after cesarean section. The remarkable feature of these abdominal pregnancies is that they may continue to near term before an occasion for diagnosis may even arise, even in the face of repeated ultrasonographic studies. The incidence of abdominal pregnancy is estimated to be roughly 1 in 10,000 live births.
ECTOPIC PREGNANCY II—RUPTURE, ABORTION
Very rarely does a tubal pregnancy develop longer than into the fourth or ﬁfth month without symptoms and signs that ultimately lead to the diagnosis. The most frequent outcome of tubal pregnancy is abortion through the tube into the peritoneal cavity. It usually occurs between the middle of the second and the end of the third month, but it may come earlier. A partial or total separation of the trophoblast from the tubal walls occurs, leading to death of the embryo. Blood extravasation and later extrusion of the embryo with blood clots into the peritoneal cavity follow, where they may slowly be absorbed, provided the hemorrhage was slight. The uterine decidua may sometimes separate as a whole and be eliminated as a decidual cast of the uterine cavity. Passage of the decidual cast can be confused with an early spontaneous abortion, and hence the passed tissue should be carefully examined.
ECTOPIC PREGNANCY I—TUBAL PREGNANCY
Ectopic pregnancy refers to the implantation of the embryo in any place outside the uterine cavity. According to the site of implantation, four kinds of ectopic pregnancy are distinguished: tubal, ovarian, abdominal or peritoneal, and cervical. Between 10 and 15 of every 1000 pregnancies are ectopic, with the rate varying with age, race, and geographic location (highest in Jamaica and Vietnam).
HORMONAL FLUCTUATIONS IN PREGNANCY
In addition to its function as the agent of transfer of gases and nutrients, the placenta also has signiﬁcant endocrine activity. It produces progesterone, which is important in maintaining the pregnancy; somatomammotropin (also known as placental lactogen), which acts to increase the amount of glucose and lipids in the maternal blood; estrogen; insulin-like growth factors; relaxin; and –human chorionic gonadotrophin (β-hCG). This hormonal activity is the main cause of the increased maternal blood glucose levels seen in pregnancy, which results in an increased transfer of glucose and lipids to the fetus.