Peter S. Warren

Fetal umbilical venous flow measured in utero by pulsed Doppler and B-mode ultrasound: I. Normal pregnancies

Umbilical venous blood flow was measured with a pulsed Doppler unit, which was used in combination with a B-mode ultrasonic imaging system to permit location of the umbilical vein and measurement of its cross-sectional area. The accuracy and limitations of the method are discussed. Forty-seven normal fetuses with gestational ages ranging from 22 weeks to term were studied on a total of 61 occasions. Flow increased with gestational age until 36 weeks, was maximal between 37 and 38 weeks, then decreased during the last 2 weeks of pregnancy. Flow per unit of fetal weight was constant during pregnancy until 36 to 37 weeks, when a reduction occurred.

A twin study of polycystic ovary syndrome.

OBJECTIVE To examine the role of genetic and environmental factors in polycystic ovary syndrome (PCOS) by using the classic twin model. SETTING Outpatient clinic of the Royal Hospital for Women, Paddington, Sydney, New South Wales, Australia. PATIENTS A group of 19 monozygotic (MZ) and 15 dizygotic (DZ) twin pairs identified from the national twin register. INTERVENTIONS Ultrasound, clinical, and biochemical parameters were used to define PCOS. RESULTS Eleven pairs of twins (5 MZ, 6 DZ pairs) were scan-discordant (i.e., one twin had scan-PCOS and the co-twin did not). Model-fitting analysis suggested that fasting insulin level, androstanediol glucuronide, and body mass index (BMI) were significantly influenced by genetic factors. CONCLUSION This study suggests that PCOS is not the result of a single autosomal genetic defect, but rather environmental factors, perhaps both intrauterine and extrauterine, are involved in the pathogenesis of this disorder or that PCOS may be an X-linked disorder or the result of polygenic factors. However, fasting insulin level, androstanediol glucuronide, and BMI did appear to be under significant genetic influence.

Early Growth Retardation in the First Trimester: Is it Characteristic of the Chromosomally Abnormal Fetus?

Summary: There have been recent reports on a small number of cases which suggest that the detection of early growth retardation might allow recognition of the chromosomally abnormal fetus in the first trimester of pregnancy. To amplify these observations, the crown‐rump length (CRL) measurements between the 64th and 86th day of menstrual age were determined in (a) 500 control high risk patients in whom a normal karyotype was subsequently demonstrated by chorionic villus sampling (CVS) and (b) 25 chromosomally abnormal fetuses. The data indicate that early growth retardation, as expressed by a small CRL measurement, is not a special characteristic of the chromosomally abnormal fetus in the first trimester of pregnancy. The CRL measurement is therefore not a useful marker or screening test at that time, except perhaps for triploidy. The well documented growth retardation with trisomy 21 and trisomy 18 which has been observed in the second trimester does not begin until after the 12th week of menstrual age.

Ultrasound in the diagnosis and management of urinary tract disorders in the fetus.

Ultrasonic echography allows display of the fetal kidneys and urinary bladder from the 16th week of pregnancy, and the possibility of detection of a number of major congenital abnormalities of the urinary tract from that time. In the second half of pregnancy ultrasound has the key role in monitoring the progress of previously diagnosed abnormalities, particularly those of an obstructive nature. Sonologists thereby have an increasing responsibility in the obstetric care of the patient not only in the narrow field of diagnosis but in the wider field of management. Examples of conservative and surgical management of obstructive lesions are given.

Completed Follow-up of 1,000 Consecutive Transcervical Chorionic Villus Samplings Performed by a Single Operator

Summary: Completed follow‐up data on 1,000 patients undergoing transcervical chorionic villus sampling (CVS) performed by a single operator at the Royal Hospital for Women is presented. Prior to the introduction of CVS, approximately 750 amniocenteses were performed annually in this unit. Over the past 5 years the total number of patients having CVS or amniocentesis has increased by Vi and almost Vi of procedures are now done by CVS.

Observations of fetal lung reflectivity using real-time ultrasound.

Summary: The ultrasonic appearance of the fetal lung alters as pregnancy progresses and this is expressed as increased reflectivity to ultrasound. Evidence is presented that demonstrates that these changes can be induced and that they may reflect increasing lung maturity.

Chorionic V ill us Sampling Clinical Experience in 50 Diagnostic Cases

Summary: The results of 50 diagnostic chorionic villus samplings (CVS) are presented. In all but 2, the fetus was at risk of a chromosomal abnormality. Sampling was successful in 48 cases. One patient aborted 4 days after the procedure. Two patients had missed abortions diagnosed on ultrasound 44 and 56 days after CVS. Seven patients elected to have their pregnancies terminated. Ail samplings were undertaken with a specially designed cannula using realtime ultrasound guidance between 9 and 11 weeks of amenorrhoea. Endocervical swabs and blood for maternal serum alpha fetoprotein estimations before and after the procedure were routinely taken. All patients were notified of the results in 8 days or less except in 3 where long‐term cultures were necessary. Six patients have delivered and 34 pregnancies are continuing satisfactorily.

Antenatal sonographic findings of congenital anterior urethral diverticulum

Oz U, Detti L, Copel JA, Bahado-Singh R, Berry S, MartinezPoyer J, Blackwell SC. Noninvasive diagnosis by Doppler ultrasonography of fetal anemia due to maternal red-cell alloimmunization. N Engl J Med 2000; 342: 9–14. 4. Lam YH, Tang MHY, Lee CP, Tse HY. Prenatal ultrasonographic prediction of homozygous type 1α-thalassemia at 12–13 weeks of gestation. Am J Obstet Gynecol 1999; 180: 148–150. 5. Tongsong T, Wanapirak C, Srisomboon J, Piyamongkol W, Sirichotiyakul S. Antenatal sonographic features of 100 alphathalassemia hydrops fetalis fetuses. J Clin Ultrasound 1996; 24: 73–77. 6. Hernandez-Andrade E, Scheier M, Dezerega V, Carmo A, Nicolaides KH. Fetal middle cerebral artery peak systolic velocity in the investigation of non-immune hydrops. Ultrasound Obstet Gynecol 2004; 23: 442–445. 7. Leung WC, Oepkes D, Seaward G, Ryan G. Serial sonographic findings of four fetuses with homozygous alpha-thalassemia-1 from 21 weeks onwards. Ultrasound Obstet Gynecol 2002; 19: 56–59. 8. Lam YH, Tang MHY. Middle cerebral artery Doppler study in fetuses with homozygous α-thalassaemia-1 at 12–13 weeks of gestation. Prenat Diagn 2002; 22: 56–58. 9. Rochon M, Stone J. Invasive procedures in multiple gestations. Curr Opin Obstet Gynecol 2003; 15: 167–175.

Thickness of tissues intervening between the transducer and fetus and models for fetal exposure calculations in transvaginal sonography

In transvaginal scanning the tissues intervening between the fetus and transducer are relatively thin. The average thickness in the first trimester is 25 mm and reduces to 15 mm by the third trimester; the minimum thicknesses are 14 and 8 mm, respectively. Two models are proposed for calculating exposure in transvaginal scanning. The models are considered in terms of the overlying tissues and the target tissues. A fixed path, constant attenuation of 0.3 dB/MHz describes the properties of the overlying tissues throughout pregnancy. In the model used in first-trimester scanning, the target tissues of the embryo/fetus are considered to have properties similar to those of soft tissues, and they attenuate the energy at the same rate as the overlying tissues. In the model used in second- and third-trimester scanning, the bony structures of the fetus are the target tissues. These reflect 30% of the incident energy and attenuate all of the transmitted energy at their surface.

Prenatal diagnosis for hemoglobinopathies – 10 years experience using fetal blood sampling

INTRODUCTION Kan et al. (1974) made the first successful prenatal diagnosis of beta-thalassemia, followed by Alter et al. in 1975.’ Since then more than 10,000 prenatal diagnoses have been performed ~ o r l d w i d e . ~ Prenatal diagnosis (PND) has been available at the Prince of Wales Hospital since 1980. With the introduction of DNA analysis from fetal amniotic fibroblasts, and later, chorionic villous sampling (CVS), globin chain synthesis has been used less frequently, but remains necessary in those patients for whom it was too late to perform the necessary DNA studies or cases where a 100% diagnosis could not be offered with DNA analysis. The results of globin chain synthesis studies over the past decade have been analyzed and are described in this report.