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CONGENITAL ADRENAL HYPERPLASIA
Congenital adrenal hyperplasia is a recessively inherited disorder that results in salt wasting. Glucocorticoid replacement is lifesaving, and the long-term prognosis for these children is good. Androgenic cortisol precursors build up in the fetus, and female fetuses typically present with ambiguous genitalia. Mothers of previously affected offspring may be treated with steroids in suppressive doses beginning shortly after conception, which will decrease the production of androgenic steroids in the fetus.
FETAL TACHYARRHYTHMIA
In most cases of fetal tachyarrhythmia (ie, FHR > 180 beats per minute), there is no underlying anatomic congenital heart disease. Children with this condition respond well to treatment, and the long-term prognosis is good. Untreated fetuses may become hydropic, and the mortality under these circumstances.
NEONATAL ALLOIMMUNE THROMBOCYTOPENIA
When a fetus has neonatal alloimmune thrombocytopenia, the mother has a normal platelet count. Fetuses tend to have profound thrombocytopenia, which may result in spontaneous hemorrhage in utero. Various fetal therapies have been suggested, including repetitive platelet transfusions to the fetus.
Invasive Fetal Therapy
INTRAVENOUS THERAPY
The most successful and widely used form of invasive fetal therapy is the direct transfusion of erythrocytes to fetuses with erythrocyte isoimmunization. A transfusion can be directed into the fetal peritoneal cavity.
Anemia is the most common other reason to give a fetus erythrocyte transfusions. Fetal anemia usually is discovered during examination of a fetus with nonimmune hydrops. If the fetus is found to be anemic.
OBSTRUCTIVE UROPATHY
Obstructive uropathy lends itself to early detection with ultrasonography. Posterior urethral valves or bladder outlet obstructions are the most common of these disorders, but the obstruction may be at any level of the urinary tract.
In all cases of obstructive uropathy, the rationale behind treatment is that the obstruction itself will lead to permanent renal damage in the developing fetus. Obstruction of the urinary tract will lead to oligohydramnios and pulmonary hypoplasia, which is usually the cause of death in these neonates.
DIAPHRAGMATIC HERNIA
Diaphragmatic hernia is a serious fetal anomaly with a high perinatal mortality rate. Although it may be associated with other fetal anomalies, more frequently it is isolated. Death of neonates from pulmonary hypoplasia is believed to be due to compression of the normal lung in utero.