Ultrasonic b‐scanning in Rhesus incompatibility

Abstract

Three patients are presented with pregnancies complicated by Rhesus incompatibility. The presence of fetal ascites in hydrops fetalis is demonstrated with ultrasonic B-scanning and compared with conventional radiographs. The value of localizing the placenta and estimating its volume is discussed. Indexing Words Ultrasound PlacentaThe value of ultrasonic B-scanning in obstetric diagnosis is well established. This paper describes three Rhesus-negative patients who presented during their third pregnancies with Rhesus isoimmunization. The patients were referred t o the radiological department for placental localization by ultrasound prior to intrauterine transfusion t o the affected fetus. The ultrasonic features of the pregnancies are described, and are correlated with the clinical data and conventional abdominal radiographs. TECHNIQUEOur scanning apparatus is a Picker Ultrasonoscope, Model 102. We use a pulsed frequency of 2 MHz with variable intensity. Liquid paraffin is used to secure acoustic coupling and the patient is examined in the supine position and longitudinal and transverse scans are taken. In the cases illustrated, the longitudinal scans are recognized by the labelled symphysis pubis (S) on the right side of the picture. The transverse scans are labelled (R) on the patient's right side to the left of the picture. The scans are recorded on Polaroid film. Fetal Ascites Rhesus incompatibility CASE REPORTS Case 1A 32-year-old Rh-negative, gravida 3 patient was admitted at 28 weeks' gestation. The fundal height and growth were compatible with 40 weeks' gestation, suggesting the presence of polydramnios. The first pregnancy had been normal, but the second infant was severely affected by Rhesus incompatibility. The patient developed a high antibody titer during the second trimester of her third pregnancy and amniocentesis showed a high level of bilirubin in the amniotic fluid.Abdominal Radiograph (Fig. 1) There was a vertex presentation with the fetal back to the left of the maternal spine. The arms and legs were extended, suggesting a large fetal abdomen but the soft tissue outline was not visible. The ossification centers for the talus and calcaneum were present. Ultrasonogram (Figs. 2a-2f) This showed a large posterior placenta extending into the fundus and over the lower uterine segment. The outline of the fetal trunk and abdomen was clearly seen. There was obvious fetal ascites. The compact triangular collection of echoes in the fetal abdomen was interpreted as representing the liver. The biparietal diameter was 6.4 cm which is 24 weeks' gestation for our department.185 VOLUME 2, NUMBER 3

Differential diagnosis of hydrops fetalis

“…fetal conditions, such as congenital heart disease and other malformations and to pleural and peritoneal effusions causing respiratory distress or even pulmonary hypoplasia; but there are also accompanying obstetric factors such as polyhydramnios and maternal toxemia [9,10] that may in turn lead to preterm hypoxic birth. treatment and reversal in selected cases [ 1 11 , but the majority die without an established causative diagnosis.…”

Recognition of the hydropic fetus by gray scale ultrasound

“…The English literature has but few reports elucidating sonographic diagnosis of fetal hydrops due to Rh isoimmunication (7)(8)(9)(10). As the use of RhoGAM* becomes more widespread, the frequency of Rh isoimmunication problems will decrease, and the need for management of severe cases anywhere but in a high risk obstetrical institution will be infrequent.…”

Erythroblastosis fetalis: Ultrasonic diagnosis

“…Its use in the detection of fetal anomalies has involved primarily anencephaly, microcephaly, and hydrocephaly (1,2,3). A previous report compared the usefulness of ultrasonic B scanning and conventional radiography in demonstrating fetal ascites in hydrops fetalis (4). This report concerns an additional case where the ultrasound examination was instrumental in the detection of a hydropic fetus in an Rh-isoimmunized woman.…”