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The renal‐resistive index from the last 3 months of pregnancy to 6 months old
Author(s) -
Andriani G.,
Persico A.,
Tursini S.,
Ballone E.,
Cirotti D.,
LellI Chiesa P.
Publication year - 2001
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1046/j.1464-410x.2001.00085.x
Subject(s) - medicine , resistive index , pregnancy , obstructive uropathy , renal artery , kidney , urinary system , cardiology , ultrasonography , surgery , biology , genetics
Objective To measure the renal resistive index (RI, an estimate of renal vascular resistance, used to assess upper tract obstructive uropathy) from the last trimester of pregnancy to the sixth month of life in a large series of healthy subjects, and thus to identify normal values that can be used routinely. During the first semester of life significant haemodynamic changes during the physiological development of the kidney cause considerable variability in RI, which is thus considered less reliable in this period. Subjects and methods From September 1998 to October 1999, 93 subjects (186 renal units, RU) were enrolled; 32 were fetuses in the last trimester of pregnancy (group 1, 64 RU) and 61 were children (122 RU), 30 aged 0–1 month (group 2, 60 RU), 20 aged 1–3 months (group 3, 40 RU) and 11 aged 3–6 months (group 4, 22 RU). All subjects underwent colour Doppler ultrasonography and the RI of the renal artery was measured for each kidney. Results The RI was very high in group 1 but decreased noticeably during the first 6 months of life, reaching values similar to those in adults after the third month. The variability in RI continuously declined with age, becoming less important. The normal ranges for groups 1–4 were 0.67–0.88, 0.57–0.90, 0.60–0.84 and 0.65–0.75, respectively. There were no statistically significant differences between the left and right kidneys. Conclusion In the first semester of life there is more than one landmark value of RI depending on the month of age of the infant. This should be considered when assessing upper tract obstructive uropathies after birth and the RI should be compared with the normal ranges reported herein.