The role of second trimester ultrasound in the diagnosis of placental hypoechoic lesions leading to poor pregnancy outcome

Objective. The purpose of the study was to quantify placental hypoechoic areas without blood flow by means of second trimester high-resolution ultrasound with power color Doppler and to evaluate its relationship to pregnancy outcome. Methods. Patients referred for second trimester ultrasound from January 2001 to December 2003 were eligible for the study. Patients with placental parenchymal hypoechoic areas without blood flow constituted the study group (N=65). The control group was comprised of 65 patients who had normal placental parenchyma. The groups were similar with regards to maternal age, gestational age, parity, race, and smoking. The mean of the two largest lesion diameters was used for severity classification. Results. Fifty-two patients (80%) had aggregate lesions of <= 5 cm and 13 (20%) had lesions > 5 cm. Mean standard deviation (SD) gestational age at delivery was 39.1+/-1.8 weeks for the control group, 37.9+/-2.8 weeks for those with lesions of <= 5 cm, and 35.2+/-5.8 weeks for those with lesions > 5 cm (p<0.0001). Mean birth weight SD was 3348+/-492 g for the controls, 3134+/-657 g for those with lesions of <= 5 cm, and 2524+/-1339 g for those with lesions > 5 cm (p=0.0005). The incidence of intrauterine growth restriction was 9.6% in the group with lesions of <= 5 cm and 38.4% in the group with lesions > 5 cm, compared to 3.1% in the control group (p=0.0003; odds ratio (OR)=5.7, p=0.015). The incidence of preeclampsia in the control group was 0.0%, in the group with lesions of <= 5 cm was 7.7%, and in the group with lesions > 5 cm was 15.4% (p<0.0214; OR=14.3, p=0.014). Conclusions. Increased size of hypoechoic placental lesions is associated with increased risk for adverse perinatal outcome. Such lesions might be the result of intervillous space thrombosis, and ultrasound may be a useful tool in the identification of patients with pro-thrombotic abnormalities. The capability to identify patients with placental thrombosis will help us to identify those patients who will benefit most from anti-thrombotic treatment.