Decreasing risk of pregnancy loss following chorionic villus sampling. Elimination of transabdominal chorionic villus sampling during the ninth week of pregnancy.

Chorionic villus sampling (CVS) is a method of obtaining fetal cells in the first trimester of pregnancy for genetic analysis. The transcervical (TC) approach was the first technique to be widely used. In the National Institute of Child Health and Human Development collaborative study the absolute loss rate following CVS (the total number of spontaneous abortions and neonatal deaths following CVS) was 4%. More recently the transabdominal (TA) approach has been introduced. This study compares the loss rates for the two approaches at various gestational ages for three 6-month periods following the addition of the TA approach with each other and with the loss rates prior to the introduction of TA CVS. We found that the percentage of pregnancy losses following TA CVS during the ninth week of gestation (63-69 days) was consistently higher than for TC CVS performed at the same gestational age. The loss rate for TC CVS has steadily decreased since the introduction of TA CVS after remaining the same for the two years prior to the introduction of the TA approach. After minimizing the number of TA CVS performed during the ninth week of gestation, the overall loss rate during the most recent 6-month period has been reduced to 0.94%. We conclude that the lowest loss rate following CVS can be obtained if both the TA and TC methods are available, and that the number of TA procedures performed during the ninth week of gestation is minimized.

The decidua-chorionic sac: a reliable sonographic indicator of intrauterine pregnancy prior to detection of a fetal pole.

Morphologically, the uterus in early intrauterine pregnancy, unlike ectopic pregnancy, contains both decidua and a chorionic sac. In view of this fact, a prospective study was performed to determine the accuracy of the demonstration of an intrauterine decidua-chorionic sac (DCS) in differentiating early or small intrauterine pregnancies (IUPs) without a demonstrable fetal pole from the intrauterine findings of ectopic pregnancy. The DCS was seen in 78 patients with proven IUPs and was not present in 52 consecutive patients with proven ectopic pregnancy (100 per cent accuracy). The decidua-chorionic sac is defined, and its relationships to the "double sac," double decidual sac, pseudosac, "crescent," pseudogestational sac, and the discriminatory human chorionic gonadotropin zone are discussed.

Detection of fetal cardiac activity between 41 and 43 days of gestation.

Using a high-resolution real-time arc sector scanner, fetal cardiac activity was detected in ten normal intrauterine pregnancies, including one triplet gestation, between 41 and 43 days of gestation. Fetal heart rates ranged from 96 to 120 beats/min (mean 110) and were detected contiguous with the yolk sac as a tiny blinking, flashing, and/or rocking echo with a regular rhythm. The mean gestational sac fluid diameters ranged from 8 to 16 mm and the crown-rump lengths, when measurable, were less than 4 mm. The demonstration of early fetal cardiac activity in utero reduces parental anxiety and indicates a favorable prognosis in patients with threatened abortion, and virtually excludes the diagnosis of ectopic pregnancy.

Chorionic villi sampling: a new technique for detection of genetic abnormalities in the first trimester.

Chorionic villi sampling (CVS) was performed on 22 patients who were at risk for a variety of genetic disorders between 8.5-11 weeks of gestation to determine whether the developing fetus had a chromosomal and/or biochemical disorder. A thin Portex catheter was passed transcervically into the chorion frondosum under constant real-time ultrasound guidance, and chorionic villi were obtained by gentle suction. The villi, which have the same genotype as the fetus, were processed directly for chromosomal and/or biochemical analysis. Results were available within six to 24 hours and were confirmed by short term cell cultures within three to ten days. One fetus affected with Tay-Sachs disease and one fetus with trisomy 16 were detected. There were no instances of fetal loss or major complications. In contrast to amniocentesis, the procedure is performed early in pregnancy and results of the genetic testing are available during the first trimester, which allows a first trimester termination of pregnancy if an abnormality is detected and greatly reduces parental anxiety if the findings are normal. We believe that CVS offers an alternative to amniocentesis in the detection of genetic disorders.

Accuracy of placental localization by ultrasound.

In a retrospective study, ultrasound diagnoses were correct in 93% of 164 patients referred for examination because of suspected placenta praevia. There was one false-negative finding in 13 cases of proven placenta praevia, and ten false-positive errors in 151 true-negative cases. False-positive results represented the largest number of errors. Examination of the patient with an empty bladder, in addition to the routine technique, is suggested to reduce the number of false-positive results.