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AbstractAims:To evaluate the sonographic appearance of suspected fetal cardiac rhabdomyomas and their evolution until delivery and in the postnatal period.Methods:The study group consisted of 6 patients at 23–37 weeks of gestation referred to our Ultrasonic Unit, between March 1992 and December 1998, for suspected fetal cardiac rhabdomyomas.Results:The cardiac tumors were single in three cases and multiple in the other cases. The size ranged from 11 to 47 mm. In two cases the tumors arose from the right ventricle, in one case from the interventricular septum and in three cases from the left ventricle. Five infants are alive and in satisfactory hemodynamic compensation, but three of them developed tuberous sclerosis. In two infants a regression in the maximum diameter of the tumor masses has been observed. One child underwent surgical treatment at the age of six months and the baby died after surgery.Conclusions:Two-dimensional and Doppler echocardiography are useful non invasive methods to diagnose fetal cardiac rhabdomyomas and to monitor their influence on the fetal cardiac function. However they do not allow us to recognize which fetuses presenting with features compatible with rhabdomyomas will develop tuberous sclerosis.

An anastomosis between the two umbilical arteries, located approximately within 3cm from the placental insertion, has been previously described at delivery and in utero. However, the prenatal investigation of the Hyrtl anastomosis is limited to case reports. We report a series of antenatal functional evaluations of this vessel. Forty-one women underwent a target ultrasonography to evaluate the blood flow characteristics of the Hyrtl anastomosis. The resistance index of the anastomosis and the umbilical arteries resistance indices before and after the anastomosis were obtained. The direction of the blood flow in the anastomosis was determined by color Doppler evaluation. An anastomosis between the two stems of the umbilical arteries was present in 36 cases while a fusion of the two umbilical arteries was found in the remaining five cases. The median (range) gestational age at diagnosis was 33.1 weeks (25.5–40.1). The median diameter of the anastomosis was 2.3mm (1.3–7.1). The blood flow in the anastomosis was pulsatile with a median resistance index of 0.62 (0.45–0.85) and unidirectional toward the umbilical artery with lower resistance index. The difference between the resistance indices of the two umbilical arteries was higher after than before the anastomosis [0.07 (0–0.3) versus 0.04 (0–0.17),P=0.05]. The median diameter of the Hyrtl anastomosis was significantly higher when the anastomosis was oblique (n=8) than when it was transverse (n=28) (4.8mm [2–7.1] versus 2.3mm [1.3–5.3], P<0.05). In three out of the five cases with fusion of the two umbilical arteries the placental insertion was marginal or velamentous. We conclude that the Hyrtl anastomosis may act as a pressure-equalizing system between umbilical arteries. This supports the hypothesis that the Hyrtl anastomosis plays an important role when the placental territories supplied by the umbilical arteries are different in size.

The presence of a communicating vessel, the Hyrtl anastomosis, between the umbilical arteries is well described in pathological studies. Using different injection techniques, it has been speculated that this vessel acts as a pressure-equalizing mechanism between the different lobes of the placenta. However, its detection during fetal life has never been reported. We report on two cases of ultrasonographic detection and Doppler assessment of the Hyrtl anastomosis during pregnancy. A pulsatile blood flow from the umbilical artery with higher resistance to that with lower resistance has been demonstrated at the level of the Hyrtl anastomosis, which was confirmed after delivery. In addition, this report supports the hypothesis that the anastomosis plays an important role in regulating the blood pressure in the placental lobes and in equalizing the blood pressure between umbilical arteries.