Search

The role of dynamic ultrasound fetal assessment and, in particular, fetal biophysical profile scoring in the recognition and management of the high-risk pregnancy is discussed. Specific details pertaining to performing and interpreting the fetal biophysical profile score are provided. In addition, the specific application of their methods to the postdate, diabetic pregnancy and the fetus with intrauterine growth retardation is discussed.

The efficacy of real-time ultrasound for the diagnosis of fetal death or hydatidiform mole was evaluated during a 1-year period. During this time, 116 patients were referred to the obstetric ultrasound service for the confirmation of clinical diagnoses. In 24 of 46 patients (52%) presenting in the first half of pregnancy, the referring diagnosis was confirmed. In 1 case of an early intrauterine pregnancy with a degenerating myoma, the ultrasound diagnosis of molar pregnancy was in error. In 48 of 70 patients (69%) referred after 20 weeks' gestation, the clinical diagnosis was confirmed. In no instance was either a false-positive or false-negative diagnosis made with real-time ultrasound in the last half of pregnancy. This method should prove to be the method of choice in diagnosing intrauterine fetal death.

Qualitative amniotic fluid volume (AFV) was determined by a linear array ultrasound method in 120 patients referred with a diagnosis of intrauterine growth retardation (IUGR). Eighty-nine of these patients were delivered of a normal infant; the false positive rate by clinical methods alone was 74.2%. Qualitative AFV was termed normal if at least one pocket of amniotic fluid measuring 1 cm in its broadest diameter was identified. Qualitative AFV was normal in 91 patients, and 86 were delivered of a normal fetus (93.4%). In contrast, qualitative AFV was decreased in 29 patients, and 26 were delivered of a fetus with IUGR (89.9%). These differences were highly significant. Perinatal morbidity was increased tenfold in patients with decreased AFV. Overall, 26 of 31 IUGR fetuses (83.4%) demonstrated decreased qualitative AFV.

Cord presentation was diagnosed antenatally in nine patients at term referred for fetal ultrasound assessment (incidence of 0.61%). Seven patients were delivered by cesarean section; cord position was confirmed in four and suspected in three patients. There were two vaginal deliveries, one following spontaneous version and the other a stillbirth associated with cord prolapse.

Biophysical profile scoring was the principal technique of antepartum fetal surveillance in 238 well-controlled diabetic pregnancies. Fifty insulin-dependent diabetics had twice-weekly testing, and 188 gestational diabetics had weekly testing. Intervention was not pursued unless there were maternal or fetal complications. There were no stillbirths and three neonatal deaths, all resulting from congenital anomalies, giving a corrected perinatal mortality rate of 0. The incidence of abnormal biophysical profile scores, eight of 238 (3.3%) overall, was low, with no significant difference between types of diabetics. In those with an abnormal score, intervention was mandated; the cesarean section rate was 50% and the rate of intensive care nursery admissions was high. Of the 230 fetuses with a normal biophysical profile score, 200 (87%) were delivered at term with minimal maternal or neonatal morbidity. Amniocentesis for phospholipid profile was performed in only 33 cases (13.9%). Hyaline membrane disease was confined to five premature neonates (incidence 2.1%). We conclude that antepartum fetal surveillance using the biophysical profile score permits safe expectant management in the diabetic pregnancy, yielding significant clinical advantages to both mother and fetus.

Management and outcome were reviewed in 307 consecutive postterm pregnancies assessed by biophysical profile scoring. Twice-weekly scores accurately differentiated normal fetuses from those at risk for intrauterine hypoxia. When the profile score is normal, waiting for spontaneous labor results in healthy neonates and a much lower cesarean section rate (15% versus 42% for "prophylactic" induction). Confident conservative management of postterm pregnancy is possible.

Congenital heart block is an unusual cause of fetal bradycardia. Until recently, the diagnosis could be confirmed only by evaluation of the fetal cardiac electrical activity. Two cases are reported in which the diagnosis of atrio-ventricular (A-V) dissociation was confirmed in the antepartum period by real-time ultrasound evaluation of cardiac mechanical activity.

Antepartum fetal heart rate monitoring based on the association of fetal heart rate accelerations with fetal movements (non-stress test) is a standard method for fetal surveillance. Application of this method requires a continuous fetal heart rate recording monitor. Audible detection of heart rate accelerations was compared with recorded accelerations in 100 tests. A listening observer detected 77.7 per cent of all accelerations with an amplitude of at least 15 beats/minute. This allowed the detection of 94.2 per cent (82 out of 87) reactive non-stress tests. In no case was a non-reactive test called falsely reactive by the listening observer. This method may be useful for assessing fetal condition when continuous fetal heart rate monitors are not available.

This study reviews the roles of sonographic assessment of the rate of growth of the fetal abdominal circumference, the femur length/abdominal circumference ratio, and qualitative determination of amniotic fluid volume as gestational age-independent indices for identification of the small for gestational age fetus. The sensitivity and specificity for single and combinations of test results were evaluated in 50 appropriate for gestational age and 40 small for gestational age fetuses. Positive and negative predictive values were derived for the general population. Our results indicate that either a rate of growth of the fetal abdominal circumference less than or equal to 10 mm/14 days or a femur length/abdominal circumference ratio greater than or equal to 23.5 correctly identifies most small for gestational age fetuses. When the general population is screened, only 15% of small for gestational age fetuses will be missed by this combination of criteria. The presence of a pocket of amniotic fluid less than or equal to 2.0 cm is highly suggestive of a small for gestational age fetus. However, the presence of a pocket of amniotic fluid greater than 2.0 cm does not guarantee an appropriate for gestational age fetus. We conclude that these gestational age-independent indices of fetal growth offer useful tools for differentiating between the small for gestational age and appropriate for gestational age fetus.

The role of ultrasound in detecting fetal anomalies in general and genitourinary tract anomalies in particular has undergone, and continues to undergo, remarkable changes. The diagnostic process began with a focus on the structural nature of anomalies and now has moved forward to include a detailed assessment of the functional nature and sequelae of these lesions. Concurrent with this shift in diagnostic emphasis has been the development of the role of ultrasonography in guiding invasive diagnostic procedures, such as percutaneous fetal blood sampling and fetal urine aspiration, and in guiding therapeutic procedures, such as chronic in utero vesicoamniotic shunt placement. These changes are occurring against a background of the role of ultrasound in assessing pathophysiology of the anomaly and assignment of prognosis, two decisions that profoundly influence pregnancy management. The challenge for the perinatal ultrasonographer is now not only to recognize the lesion, but also to institute the further investigative steps upon which a rational management plan may be based. As illustrated in this brief review of the more common genitourinary tract anomalies, the range of outcome and the pathophysiologic progression of the disease are both wide and complex. Continued improvements in ultrasound technologies and application hold the key to the ultimate reduction in the clinical significance of these common fetal diseases.