Doppler sonography of uterine arteries at 20-23 weeks: depth of notch gives information on probability of adverse pregnancy outcome and degree of fetal growth restriction in a low-risk population.

OBJECTIVE

Our purpose was to assess the relation between the depth of notch in the uterine arteries at 20-23 weeks and the incidence and severity of subsequent pregnancy complications.

METHODS

The Notch Index (NI) was defined as (C - D)/C, with C = postsystolic zenith and D = postsystolic nadir. For evaluation, the mean NI of the two uterine arteries was determined. Adverse pregnancy outcome was defined as presence of SGA < or =5th percentile, pre-eclampsia, preterm delivery <33 weeks, placental abruption or intrauterine or neonatal death. Women who received preventive treatment (Aspirin or low-molecular heparin) were excluded.

RESULTS

A notch was present in 957 of 15,888 singleton pregnancies (6.0%; unilateral = 4.37%, bilateral = 1.66%). The incidence of adverse pregnancy outcome was 5.3%; it increased from 4.6% for women without notch to 41.8% for those with a mean NI > or =0.2 and higher. Moreover, higher mean NI values tended to be associated with lower birth weight. In addition to the maternal age, parity, mean Pulsatility Index and presence of notch, the depth of notch made an additional significant contribution to the assessment of the probability of adverse pregnancy outcome.

CONCLUSION

Besides the classic parameters such as maternal age, history of adverse pregnancy outcome, parity, impedance and the presence of notch, also the depth of notch seems to be valuable in the assessment of adverse pregnancy outcome risk. Especially in cases where very high or very low values of NI are measured, quantification of the depth of notch may give more information than the description of the presence of notch alone. This might be of value for future multivariate models for risk assessment of adverse pregnancy outcome.