A non-human primate model for the in utero chronic catheterization of the umbilical vein. A preliminary report.

Short-term ultrasound-guided fetal umbilical cord catheterization in humans has been reported. However, before chronic umbilical vein catheterization is attempted in humans the technique must be tested in the non-human primate model. If the fetus was to tolerate this procedure, chronic fetal umbilical vein catheterization could be used for drug administration, parenteral fetal nutrition or to monitor the changes of hematologic parameters during and after open or endoscopic fetal surgery. In this study, 4 pregnant baboons were used to test the feasibility of ultrasound-guided umbilical vein catheterization. Although the umbilical vein was successfully catheterized in all the animals, only 1 fetus survived the postoperative period. The 3 immediate fetal deaths were due to a fetal intra-amniotic hemorrhage, while the most likely cause of death of the 4th animal was infection. In the surviving fetus and mother, blood was sampled once a day. Neither fetomaternal hemorrhage nor thrombosis could be documented. We conclude that ultrasound-guided transplacental umbilical vein chronic catheterization is technically difficult but feasible in the baboon model. Further studies in this model are needed to improve the catheterization technique and to monitor the extent of time that the catheter may be tolerated within the umbilical vein.

Fetal umbilical cord ligation under ultrasound guidance.

In a patient with severe twin-to-twin transfusion syndrome, ultrasound-guided umbilical cord ligation of the hydropic recipient twin was performed at 27 weeks' gestation. The procedure was successful in arresting the blood flow and was associated with improvement in the condition of the severely compromised donor fetus. At 29 weeks' gestation, premature onset of labor occurred and a healthy baby was delivered by emergency Cesarean section. This report demonstrates the feasibility of ultrasound-guided cord ligation for selective feticide in a case of severe twin-to-twin transfusion syndrome.

Serum erythropoietin in small for gestational age fetuses.

Serum erythropoietin (Epo) concentration was compared prenatally in adequate (AGA) and small for gestational age (SGA) fetuses. Fifty-four percutaneous umbilical blood samplings were paired with maternal blood and assessed for Epo, hematocrit and reticulocyte count. Seventeen fetuses were growth-retarded (SGA) on the basis of ultrasonic biometry and birth weight. Controls (AGA; n = 37) underwent cordocentesis for risk of toxoplasmosis, maternal age or malformations (CNS, GI, heart). No cytogenetic abnormality or infections was found in the 54 fetuses. Linear and polynomial regressions were fitted to determine correlations between parameters. Nonparametric Mann-Whitney test was used for comparison between groups. Gestational age at sampling was similar in AGA and SGA. The SGA fetuses had a higher Epo concentration than controls (p < 0.001). Fetal AGA Epo increased significantly throughout pregnancy (p < 0.01) but did not correlate with maternal Epo (p > 0.05). An inverse correlation was found between fetal reticulocyte count and Epo concentration (p < 0.02). The mechanism of high Epo level in SGA fetuses may involve low pO2 and hemoconcentration.

Fetal blood cell membrane fluidity in small for gestational age fetuses.

Blood cells membrane fluidity was assessed prenatally by fluorescence polarization for anisotropy, microviscosity, degree of order and fusion activation energy in 20 fetuses who underwent percutaneous umbilical blood sampling for intrauterine growth retardation (IUGR) and in 25 controls for normal weight sampled for other indications. Simultaneously, blood samples were collected from each mother for comparison. Regulators of membrane fluidity (i.e., cholesterol, phospholipids, free fatty acids) were also assessed. Student t test was employed for analysis. Membrane fluidity was lower in control fetal cells than in adults (p < 0.05) and lower in IUGR fetuses than in controls (p < 0.05). The mechanism may involve a low cholesterol concentration and a low unsaturated/saturated free fatty acids ratio in fetal blood cells membranes and plasma. Fetal cells membrane fluidity reflects in part fetal nutritional status.

Pseudo-meconium ileus due to cytomegalovirus infection: a report of three cases.

We observed three cases of antenatal ileus associated with cytomegalovirus (CMV) infection of the fetus and placenta. Two were detected antenatally because of increased echogenicity of the lower abdomen. In the first fetus, the ileus was associated with abnormalities of amniotic fluid enzymes but it was transient and not present at autopsy and the CMV infection was mild, without inflammatory infiltration or necrosis. In the two others, the ileus persisted and CMV-associated lesions were severe. In all three cases the virus was demonstrable in ganglion cells or within myenteric and submucosal plexuses all along the small and large intestine; ileus was imputed to CMV, which caused a paralytic ileus, and in one fetus meconium ileus was also present. A transient episode of ileus does not indicate that the fetus is free of disease and a wide range of causes must be considered, including CMV infection as well as the more usual causes such as cystic fibrosis (CF) and Hirschsprung's disease.