Second-trimester pregnancy termination for genetic abnormalities.

Abstract

2nd trimester pregnancy termination techniques are reviewed in this discussion, and attention is directed to some of the special needs of couples with a genetically abnormal fetus. Focus is on the psychological considerations, the medical techniques (prostaglandins, hypertonic saline, and hypertonic urea), and surgical techniques (dilatation and evacuation and abdominal operations). Patients who present for genetic diagnosis are generally older, more often married, and desirous of a healthy pregnancy outcome. The grief response is common and understandable when one considers that amniocentesis results are not known until after quickening and that patients have seen the ultrasonic image of their living fetuses at the time of amniocentesis. Patients differ in their manner of dealing with the loss of their hoped for healthy children, and the physician must be sufficiently sensitive to assess the individual patient's needs rather than give the same advice when counseling every patient. The patient and her partner may want to vent their immediate feelings or concentrate on the objective details of the termination procedure. In any case, the various available methods of terminating the pregnancy should be reviewed along with their advantages and disadvantages. Prostaglandins should be used with caution and are contraindicated for the following conditions: hypersensitivity; pelvic inflammatory disease; unfavorable fetal position; and placenta previa. Careful monitoring of uterine contractions should be done. The primary advantage of prostaglandins in terminating a pregnancy with a malformed or genetically abnormal fetus is the removal of an intact fetus for morphologic examination and for other diagnostic tests to confirm the antenatal diagnosis. Hypertonic saline promotes uterine contractions by drawing fluid from the vascular and extravascular space. 100 milliliters of amniotic fluid is removed with a 20 gauge spinal needle, and 200 ml of a 20% saline solution instilled over 10-20 minutes. Hypertonic saline offers the advantage of the strong likelihood of stillbirth and a higher percentage of complete urine evacuation. Hypertonic solutions of urea are used as an abortifacient. Their disadvantages, as with hypertonic saline, include intravascular instillation or myonecrosis if the injection is in the uterine muscle. The proper surgical technique calls for considerable cervical dilatation for adequate uterine evacuation. Before 16 weeks' gestation surgical termination is safer than an instillation procedure. After 16 weeks there is no difference in maternal mortality. The primary advantage of surgical termination for a patient with an abnormal fetus is the speed and painlessness with which the procedure can be performed. A hysterectomy or hysterotomy is unnecessary unless there is another gynecologic complication or if other methods of pregnancy termination are unavailable or unsuccessful. Uterine evacuation using vaginal prostaglandin suppositories is preferred.