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Antepartum fetal surveillance constitutes an essential component of the standards of care in managing pregnancies complicated with pregestational diabetes mellitus. Fetal hyperglycemia is associated with increased oxidative metabolism, hypoxemia, and increased brain and renal perfusion without any significant changes in fetoplacental perfusion. Moreover, the relationship between abnormal umbilical arterial Doppler indices and the quality of glycemic control remains unproven; however, observational studies suggest significant diagnostic efficacy of the umbilical arterial Doppler method in diabetic pregnancies complicated with FGR or hypertension. Although there are no randomized trials specifically addressing this issue, existing evidence suggests that Doppler velocimetry of the umbilical artery may be beneficial for antepartum fetal surveillance in diabetic pregnancies in the presence of these complications. Such utilization should be integrated with the existing standards of practice.

Obstetrical management of isoimmunized pregnancy is determined by the severity of fetal anemia. Early and accurate diagnosis of anemia makes safe and effective clinical management. In fetal Rh disease, fetal anemia leads to cardiovascular changes in blood flow through the major fetal vessels, detectable by Doppler velocimetry is particularly attractive since examination can be quick, safe and cost-effective.

A comprehensive review of Doppler velocimetry revealed significant variability in the design and conduct of these studies. Areas of variability include differences in ultrasound machines used, Doppler modality (continuous value vs pulsed Doppler), Doppler indices used, and definition of prolonged pregnancy and precision of pregnancy dating. The Doppler technique requires experience and precision that are difficult to ensure and maintain across different trials. The extreme variability observed is likely to overwhelm any small or moderate correlation between Doppler measurements and outcomes, should they exist. The generally small size of the study samples and the near universal lack of power analysis for studies with negative results represent significant additional hurdles. Properly designed and sufficiently powered trials would therefore still be of benefit. An interesting empirical observation was that umbilical Doppler velocimetry appeared to better predict outcome in prolonged pregnancy when compared with the standard antenatal tests such as NST and fluid volume assessment. This is certainly an observation that merits further investigation.

There is ample evidence that Doppler indices from the fetal circulation can reliably predict adverse perinatal outcome in an obstetric patient population with a high prevalence of complications, such as fetal growth restriction and hypertension. This efficacy is not evident, however, in populations with a low prevalence of pregnancy complications. It is also apparent that fetal Doppler indices are capable of reflecting fetal respiratory deficiency with varying degrees of efficiency. The umbilical arterial Doppler indices are more sensitive to asphyxia than to hypoxia, whereas cerebral Doppler indices demonstrate significant sensitivity to hypoxia. Compared to fetal heart rate monitoring and the biophysical profile, umbilical artery Doppler velocimetry shows mostly similar and often superior efficacy. Furthermore, progressive fetal deterioration manifests in sequential abnormalities of the various fetal assessment parameters, starting with middle cerebral artery vasodilation and eventual progression to disappearance of the fetal heart rate variability, late deceleration, and the absence or reversal of the end-diastolic velocity in the umbilical artery. Evidently, no single testing modality should be regarded as the exclusive choice for fetal surveillance, as these tests reveal different aspects of fetal pathophysiology, often in a complementary manner. Clearly, more work is needed to determine the optimal integration of the various surveillance methods for improving perinatal outcome in a cost-effective manner.

It is apparent from cumulative experience that the end-diagnostic component of the umbilical arterial Doppler waveform is of crucial importance for fetal prognostication. AREDV is known to be associated with an unusually adverse perinatal outcome. Most remarkably, these infants suffer from high perinatal mortality and morbidity rates and demonstrate an increased frequency of malformations and chromosomal abnormalities, with a predominance of trisomies 13, 18, and 21. Most infants with AREDV require intensive care. Furthermore, the risk of cerebral hemorrhage, anemia, and hypoglycemia is increased. It has been observed, however, that absent end-diastolic flow may improve, although often only transiently, and that weeks or more may elapse before the fetus shows additional evidence of compromise. Obviously, the presence of absent end-diastolic flow should warn the physician of significantly increased fetal risk. Appropriate surveillance measures should be immediately undertaken. If the pregnancy is significantly preterm, consideration for delivery should include additional signs of fetal compromise. A more aggressive approach should be taken to ensure fetal maturity. If fetal anomalies are present or AEDV cannot be explained by pregnancy complications such as preeclampsia, then fetal karyotype should also be determined to rule out lethal aneuploidies. Although the benefits of emergency delivery for this phenomenon remain controversial, randomized clinical trials have shown improved outcome from intervention in pregnancies with absent end-diastolic velocity. This subject is discussed comprehensively in Chap. 26.

The development of Doppler sonography has made it feasible to assess the fetal and uteroplacental circulations. Numerous studies have established a significant association between abnormal Doppler indices and the various pregnancy disorders and adverse perinatal outcomes. Most clinical investigations suggest that, in high-risk pregnancies, umbilical arterial Doppler indices may be efficacious for predicting perinatal problems including fetal death. Many randomized trials on Doppler velocimetry have yielded positive results. Furthermore, systematic reviews of the trials by meta-analysis demonstrate a significant reduction in preventable fetal deaths. The current evidence mandates that Doppler velocimetry of the umbilical artery should be an integral component of fetal surveillance in pregnancies complicated with fetal growth restriction or preeclampsia. Obviously, no single testing modality should be regarded as the exclusive choice for fetal surveillance, as these tests reveal different aspects of fetal pathophysiology, often in a complementary manner.

Inferior vena cava (IVC) flow velocity waveforms represent both right atrial function and the blood flow pattern within the venous tree of the lower fetal body. Flow velocity waveforms obtained close to the venous entrance into the right atrium reflect mostly right atrial activity. Therefore the information obtained by studying blood flow patterns within the IVC includes (1) whether there is normal atrial filling; (2) detection of a fetal arrhythmia and the resulting blood flow pattern; and (3) estimation of hemodynamic disturbances in severely compromised fetuses. In this chapter we describe the normal pattern of IVC blood flow and the various components of the IVC flow velocity waveforms. Typical alterations of the IVC flow velocity waveforms in hydropic fetuses, fetuses with arrhythmias, and severely compromised fetuses are discussed. Finally, special attention is devoted to the significance of umbilical vein pulsations.

The ductus venosus (venous duct, ductus Arantii) is one of the three physiological shunts responsible for the circulatory adaptation to intrauterine life. It is attributed to Giulio Cesare Aranzi (1530–1589), but the first written account dates back to his contemporary Vesalius in 1561 [1]. Its function was long recognized [2, 3] but of hardly any clinical importance until ultrasound techniques were introduced [4–6]. It is now widely used as an important part of the hemodynamic assessment of the fetus [7] and has been suggested for diagnostic use after birth as well [8].