Diagnostic ultrasound ( PDFDrive )

1356 PART IV Obstetric and Fetal Sonography
TABLE 39.4 Urinary Tract Classiication System and Follow-Up
Low Risk
Increased Risk
DIAGNOSIS
Renal pelvic diameter 16-27 weeks 4-<7 mm ≥7 mm
Renal pelvic diameter ≥ 28 weeks 7-<10 mm ≥10 mm
Calyceal dilation Central only Peripheral
Parenchymal thickness Normal Abnormal
Parenchymal appearance Normal Abnormal
Ureters Normal Abnormal
Bladder Normal Abnormal
Amniotic luid a Normal or increased Oligohydramnios
FOLLOW-UP
During pregnancy One additional ultrasound ≥32 weeks Initial follow-up ultrasound in 4-6 weeks b
Postnatal to 1 month of age Two additional ultrasounds at >48 hours
1-6 months later
Consider antibiotic prophylaxis
Ultrasound at >48 hours to 1 month b
Other Aneuploidy risk modiication if indicated Aneuploidy risk modiication if indicated
Specialist consultation (e.g.,
nephrology, urology)
a Amniotic luid can be abnormal in low-risk fetuses if due to a nonrenal cause (such as intrauterine growth restriction or premature rupture of
membranes).
b Certain situations (severe abnormalities such as posterior urethral valves or bilateral severe hydronphrosis) may require more expedient
follow-up.
Modiied from Nguyen HT, Benson CB, Bromley B, et al. Multidisciplinary consensus on the classiication of prenatal and postnatal urinary tract
dilation (UTD classiication system). J Pediatr Urol. 2014;10(6):982-998. 133
TABLE 39.5 Risk of Postnatal Pathology by Degree of Antenatal Hydronephrosis
DEGREE OF ANTENATAL HYDRONEPHROSIS, % (95% CONFIDENCE INTERVAL)
Pathology Mild Moderate Severe P Value
Any pathology 11.9 (4.5-28.0) 45.1 (25.3-66.6) 88.3 (53.7-98.0) <.001
Ureteropelvic junction 4.9 (2.0-11.9) 17.0 (7.6-33.9) 54.3 (21.7-83.6) <.001
Vesicoureteral relux 4.4 (1.5-12.1) 14.0 (7.1-25.9) 8.5 (4.7-15.0) .10
Posterior urethral valves 0.2 (0.0-1.4) 0.9 (0.2-2.9) 5.3 (1.2-21.0) <.001
Ureteral obstruction 1.2 (0.2-8.0) 9.8 (6.3-14.9) 5.3 (1.4-18.2) .025
Other a 1.2 (0.3-4.0) 3.4 (0.5-19.4) 14.9 (3.6-44.9) .002
a Includes prune belly syndrome, VATER syndrome, and unclassiied.
Hydronephrosis was classiied based on anteroposterior diameter of renal pelvis:
Second trimester: mild 4-<7 mm, moderate 7-10 mm, severe >10 mm.
Third trimester: mild 7-<9 mm, moderate 9-15 mm, severe >15 mm.
Modiied from Lee RS, Cendron M, Kinnamon DD, Nguyen HT. Antenatal hydronephrosis as a predictor of postnatal outcome: a meta-analysis.
Pediatrics. 2006;118(2):586-593. 149
is lacking. 132,157,158 here are no uniformly accepted guidelines
regarding antibiotic prophylaxis, postnatal workup, and surgery.
However, a postnatal renal ultrasound is the irst examination
of choice. In the neonate, the relative state of dehydration and
physiologic oliguria in the irst 24 to 48 hours of life can result
in underestimation of the degree of dilation and a false-negative
renal ultrasound. 159 herefore ultrasound should not be performed
before 48 hours ater birth, except for cases of oligohydramnios,
urethral obstruction, and bilateral high-grade dilation. It is
important to recognize that hydration status can cause a transient
increase in renal pelvic size and also has an efect on the bladder
volume. In the presence of UT dilation, ultrasound should be
repeated ater bladder emptying in order to assess accurately the
severity of UT dilation. Many authors would perform voiding
cystourethrography only when postnatal renal ultrasound
indings are abnormal. 160,161 he indication for functional renal
imaging by renal scintigraphy depends on the particular clinical
situation. Recently, magnetic resonance urography has shown
promise as a method to assess renal function without the use of
radiation. 162,163
In summary, we propose the following management protocol
for UT dilation detected in the second trimester with regard to