The value of transvaginal colour and pulse wave Doppler in the diagnosis of pathologic early intrauterine and tubal pregnancy was assessed. Forty-one normal pregnancies, 6 blighted ovum, 6 missed abortions, and 22 suspected ectopic pregnancies (13 proven tubal pregnancies) were examined. Single 5 MHz transvaginal colour and pulse wave Doppler probe was used and once clear signals from uterine vessels, umbilical artery or trophoblastic vessels were obtained. Resistance Index (peak systole--end diastole/peak systole, RI) from the corresponding waveforms was calculated. In 41 normal pregnancies (examined before termination of pregnancy) with gestational age ranged from 6 to 10 weeks mean RI in uterine artery was 0.81 (SD 0.06), in the umbilical artery 1 (SD 0), and 0.48 (0.08) in the trophoblastic vessels. Mean RI from uterine arteries in six pregnancies with blighted ovum and six with missed abortion were 0.77 (SD 0.11) and 0.69 (SD 0.13) respectively. In 2 out of 6 cases of blighted ovum and 4 out of 6 cases of missed abortion flow in trophoblastic vessels could not be detected. These findings suggest ineffective early placentation in pathologic pregnancy. Twenty-two patients with suspected ectopic pregnancy (raised serum beta HCG with empty uterus, amenorrhoea with abdominal pain and/or palpable abdominal mass) were examined. In 13 cases tubal pregnancy was confirmed by laparoscopy and/or laparotomy. In the remaining nine cases the diagnosis was excluded by means of laparoscopy or subsequent negative beta HCG. Doppler diagnosis of ectopic pregnancy was made when colour flow in adnexa with RI less than 0.56 was revealed.(ABSTRACT TRUNCATED AT 250 WORDS)