Compare and contrast five different placental problems that could cause fetal demise. Discuss clinical presentations and pathologic appearances. (<250 words)

Abruptio placenta presents with sudden onset of maternal pain and bleeding, usually in late pregnancy. It is caused by premature separation of the placenta, resulting in loss of maternal-fetal circulation and fetal hypoxia. Placenta previa occurs with implantation of the placenta over the internal os of the uterus. This can result in tearing of the placenta at the time of delivery, which threatens both the mother and the fetus. Uteroplacental insufficiency can be the result of maternal pre-eclampsia. The pre-eclampsia can can be associated with infarction, thrombosis, and decreased placental size. Placental infarctions can occur, but are usually not a threat to fetal survival unless much of the placenta is involved. The infarcts are focal areas of coagulative necrosis. When monozygous twins are present, there may be vascular anastomoses between the fetuses through the placenta, resulting in a twin-twin transfusion syndrome. One twin (donor) will be small and may die, while the other (recipient) will be larger.

(other possible answers)

Sometimes the placenta can be involved with congenital infections. Thus, the TORCH agents can cross the placenta to infect the fetus. The placenta may also be inflamed and show the organisms. This can cause decreased blood flow to the fetus, stillbirth, and premature birth. Premature rupture of membranes with infection can occur prior to delivery. The chorioamnionitis can lead to premature delivery. The infection can spread to the fetus. The leakage of amniotic fluid can result in oligohydramnios, which causes fetal deformation and pulmonary hypoplasia. An incompetent cervix could lead to rupture of membranes as well. Abnormalities in fetal movement can lead to umbilical cord problems. Excessive fetal movement results in a long cord which can become wrapped around the fetus, particularly the neck (nuchal cord) or result in a true knot. Both of these complications compromise blood supply to the fetus. Decreased fetal movement results in a short cord. Such a cord is more prone to tear during delivery. An umbilical cord that inserts into the fetal membranes, rather than into the placental disk, is more prone to compression and tearing, particularly at the time of delivery. A single umbilical artery (two vessel cord) is usually enough to supply blood to the fetus, but suggests that other anomalies are present in the fetus. The incidence of fetal growth retardation and stillbirth is greater when a two vessel cord is present.

In ectopic pregnancy, the embryo implants outside of the uterine cavity, often the fallopian tube, where there is not adequate room to develop, and rupture and hemorrhage can occur.

A bipartite placenta or placenta with an accessory lobe is more prone to trauma, often because of increased incidence of placenta previa or of velamentous (membranous) umbilical cord insertion, with resultant hemorrhage in delivery.

Placenta accreta is more of a maternal complication, because there is no decidual layer, and the placenta grows into the uterine myometrium. At the time of delivery, the placenta fails to separate properly and may require hysterectomy.

(some of you commented on meconium staining; the presence of meconium on the placenta is not a problem in itself, but a consequence of some other problem resulting in fetal distress).

Discuss possible causes with their mechanisms for respiratory failure at birth. (<250 words)

Respiratory failure in the newborn can occur as a result of several causes. Perhaps one of the most common is prematurity, because premature infants often lack adequate surfactant in their lungs since acceleration of surfactant production from type II pneumonocytes does not occur until about 35 weeks gestation. This lack of surfactant leads to hyaline membrane disease, which appears microscopically as a pink amorphous material lining alveoli. This impairs gas exchange and leads to respiratory distress.

Another cause of respiratory failure in the newborn is pulmonary hypoplasia. This can be primary (a congenital malformation) or secondary to oligohydramnios or intrathoracic mass. Oligohydramnios is a result of urinary tract abnormalities, such as polycystic kidney disease, in which there is insufficient fetal urine production. The oligohydramnios produces constraint of fetal lung development so that the lungs at birth are too small to sustain life. Mass effects from a condition such as diaphragmatic hernia can also produce deformation of the lung. The lack of development of a diaphragmatic leaf (usually left) allows abdominal contents to herniate into the chest cavity and constrain pulmonary growth.

Additional answers:

Pneumonitis at the time of birth may lead to respiratory failure. One cause for this is meconium aspiration. This occurs with fetal distress that leads to release of meconium in utero in the amniotic cavity. The meconium is then aspirated into the lungs to produce a pneumonitis. Pneumonia may also be present at birth if the baby was infected in utero, often when there was premature rupture of membranes and ascending infection into the uterine cavity that spread to the fetus.

Persistence of fetal conditions may lead to respiratory distress. Persistence of the fetal circulation with continued pulmonary hypertension can preclude closure of the foramen ovale or ductus arteriosus, maintaining the fetal type of circulation. This can lead to heart failure with edema and respiratory distress. Also, transient tachypnea of the newborn may occur when fluid present in the lung in utero is not completely absorbed.