Prenatal diagnosis of 46,XX male fetuses.

Ultrasonography can accurately determine phenotypic sex differences from those of the genetic sex. Two cases were identified; they were the result of a translocation of the SRY gene from the Y chromosome to the X chromosome during meiosis. An ultrasonographic difference may represent an otherwise unsuspected genetic abnormality.

Sex difference in crown-rump length in first-trimester twins.

OBJECTIVE: To determine if there is a difference in the crown-rump length (CRL) between male and female fetuses in the first trimester. STUDY DESIGN: CRL was determined in 77 normal twin pairs at the time of chorionic villus sampling. The sex of each fetus was assigned based upon the results of the sampling. RESULTS: A small difference was found between the CRL of males as compared to females, but this was not statistically significant. However, if there was a difference in size between the twin pairs, the odds were 1.5:1 that the larger would be male. CONCLUSION: There is no clinically significant difference in size between male and female fetuses in the first trimester of pregnancy.

Prenatal diagnosis of body stalk anomaly in the first trimester of pregnancy.

Ultrasound examination in a 10-week fetus demonstrated a marked deformity of the lower half of the fetus that was in the celomic cavity, and the upper half of the body was in the amniotic sac. There was abdominal wall defect with herniation of the liver and bowel, the lower limbs were deformed and the umbilical cord was short and thin. These abnormalities were suggestive of body stalk anomaly. The diagnosis was confirmed by pathological examination after termination of the pregnancy at 18 weeks.

Vasa previa: prenatal diagnosis with transvaginal color Doppler flow imaging.

Vasa previa carries a significant risk for fetal exsanguination and death at the time of membrane rupture. The diagnosis is rarely made before the onset of vaginal bleeding. We report the prenatal diagnosis of vasa previa with transvaginal color Doppler flow imaging in an asymptomatic patient with a succenturiate placenta.

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.

Ultrasonographic detection of the second-trimester fetus with trisomy 18 and trisomy 21.

Biparietal diameter/femur length ratio and nuchal thickness were found to be sensitive indicators for the prenatal detection of trisomy 18 and trisomy 21. A biparietal diameter/femur length ratio greater than 1.5 SD above the control mean correctly identified 5 of 11 (46%) fetuses with trisomy 21 and 3 of 4 (75%) fetuses with trisomy 18. Nuchal thickening (6 mm or more) correctly identified 5 of 12 (41%) fetuses with trisomy 21 and 2 of 4 (50%) fetuses with trisomy 18. The sensitivity and specificity of the biparietal diameter/femur length ratio in detecting either aneuploidy was 53% and 93%, respectively, whereas a thickened nuchal fold had a sensitivity of 44% and a specificity of 100%. The combined use of the two ultrasonographic measurements had an overall sensitivity of 81% and a specificity of 93%. Prospective ascertainment of these two trisomies appears warranted in low-risk populations.

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.

Fetus papyraceus in twin pregnancy.

Three cases of fetus papyraceus in twin pregnancy were seen over a 4-month period. They were associated with an antepartum stillbirth and intrauterine growth retardation of the larger twin. Two of the 3 mothers exhibited hypertension. It is concluded, therefore, that the appearance of a fetus papyraceus frequently indicates the presence of a hostile intrauterine environment. We suggest that serial ultrasonic examinations be performed to confirm the diagnosis of fetus papyraceus. In this way, appropriate therapy may be directed toward a better outcome for the second twin.