Prediction of the small for gestational age twin fetus by Doppler umbilical artery waveform analysis.

In 89 consecutive twin pregnancies, monthly Doppler ultrasound measurements were made of the umbilical artery blood flow velocity waveforms of each fetus. In total, 453 Doppler studies were performed. Of the 178 infants, 32 were small for gestational age (SGA); only 24 of the 82 SGA Doppler studies were abnormal, giving an overall sensitivity of the test in the prediction of the SGA fetus of 29% and a positive predictive value of 34%. Furthermore, neither the sensitivities nor the positive predictive values were above 50% in any of the gestational-age intervals individually studied. We conclude that Doppler study of umbilical artery flow velocities is not of much value in the prediction of SGA infants in twin pregnancies, although persistently absent end-diastolic velocities were associated with poor outcome.

Value of antenatal diagnosis of abnormalities of the urinary tract.

OBJECTIVE: To assess the value of antenatal diagnosis of abnormalities of the urinary tract on ultrasonography. DESIGN: Retrospective study. SETTING: Two obstetric units in Glasgow. SUBJECTS: 62 Fetuses in which renal abnormalities were diagnosed on antenatal ultrasonography. INTERVENTIONS: Six fetuses had their bladders aspirated to determine renal function. Fifteen pregnancies were terminated on the basis of the findings on antenatal ultrasonography, and if possible necropsy was performed on the fetuses. In babies who were born alive the final diagnosis was made by postnatal ultrasonography, intravenous urography, radionuclide scanning, cystography, and, in those who died in the early neonatal period, necropsy. Neonates who were referred with a known obstructed kidney had nephrostomy or pyeloplasty. END POINT: Assessment of the value of antenatal diagnosis of renal abnormalities on ultrasonography for babies who had no clinical evidence of disease postnatally. MAIN RESULTS: Eighteen fetuses did not survive birth; the antenatal diagnosis was accurate in all 18. Of the 44 babies born alive, five had normal urinary tracts, in two of whom antenatal ultrasonography had probably indicated a false positive diagnosis. Fourteen babies died during the early neonatal period. Twenty five babies with renal abnormalities were followed up; the antenatal diagnosis was inaccurate for 10 of them, the commonest misdiagnosis being hydronephrosis for multicystic kidney and vice versa, and there was one false positive diagnosis. The initial clinical findings in 14 babies would have led to the early detection of a urological abnormality. In the 30 babies with no clinical evidence of disease the antenatal diagnosis was of definite value in eight, probable value in 15, and marginal value in seven. Overall, an accurate antenatal diagnosis was made in 46 of the 62 cases (74%); in 12 cases renal disease was detected but its specific nature was not determined; and in four cases the diagnosis was misleading. CONCLUSIONS: The overall value of antenatal diagnosis is that it indicates early termination of fetuses with fatal renal disease, prepares parents and medical staff for the likelihood of serious neonatal problems, and shows abnormalities of the urinary tract that may not be detected postnatally.

Twin-to-twin transfusion syndrome: what are appropriate diagnostic criteria?

One hundred seventy-eight consecutive twin pregnancies were studied to reevaluate the standard diagnostic criteria for chronic twin-to-twin transfusion syndrome of an intertwin hemoglobin difference greater than 5 gm/dl and a birth weight difference greater than 20%. Hemoglobin differences greater than 5 gm/dl were found in six pregnancies with monochorionic placentas but also in seven with dichorionic placentas. Birth weight differences greater than 20% occurred no more commonly in monochorionic than in dichorionic pregnancies. Of the four pregnancies with a coexisting hemoglobin difference greater than 5 gm/dl and birth weight difference greater than 20%, only one had a monochorionic placenta and therefore likelihood of vascular anastomoses. Diagnosis of twin-to-twin transfusion syndrome cannot be definitively established by current standard diagnostic criteria.

Monozygotic twin pregnancy: diagnostic and Doppler ultrasound studies.

Of 178 consecutive twin pregnancies, 63 were both monozygotic and also studied prenatally by real-time B-scan (and usually Doppler) ultrasound. The 48 pregnancies with monochorionic placentas (in which vascular anastomoses are almost universal) were compared with the 15 monozygotic pregnancies having dichorionic placentas. The type of placenta found at delivery was predicted with substantial accuracy by ultrasound examination in mid-pregnancy. We were unable to identify any inter-group difference in fetal growth rate, discordance of fetal growth between twins or pattern of umbilical artery flow velocity waveform. In the absence of the rare florid twin transfusion syndrome, the vascular anastomoses that have been shown to be common in monochorionic placentas do not exert a strong influence on fetal growth or fetoplacental blood flow.

Effect of adrenaline on extradural anaesthesia, plasma lignocaine concentrations and the feto-placental unit during elective caesarean section.

Extradural anaesthesia was induced with either 2% lignocaine or 2% lignocaine with adrenaline 1:200,000 in 20 patients undergoing elective Caesarean section. With the adrenaline-containing solution, a smaller dose of lignocaine was required to produce an adequate block and the lignocaine concentrations in both mother and neonate were significantly smaller compared with the plain solution. Arterial pressures were less in the adrenaline group, but there was no difference in umbilical flow velocity waveform, fetal heart rate or fetal outcome. Neither feto-placental circulation nor fetal outcome were affected adversely by episodes of hypotension or the ephedrine used for treatment.