Diagnostic ultrasound ( PDFDrive )

CHAPTER
39
The Fetal Urogenital Tract
Katherine W. Fong, Julia Eva Kfouri, and Kirsten L. Weind Matthews
SUMMARY OF KEY POINTS
• Evaluation of amniotic luid volume (subjective assessment
combined with semiquantitative methods such as
maximum vertical pocket or amniotic luid index) provides
important information about some maternal and fetal
conditions, as well as placental function.
• Sonographic indings suspicious of renal cystic disease
include cysts, renal hyperechogenicity, and/or large
kidneys. Whenever renal cystic disease is suspected, it is
useful to perform a renal ultrasound of the parents to
check for unknown familial disease.
• Evaluation of urinary tract dilation should include
measurement of the anteroposterior renal pelvic diameter;
identiication of calyceal dilation and renal parenchymal,
ureteral, or bladder abnormalities; and assessment of
amniotic luid volume.
• In fetuses with lower urinary tract obstruction,
a fetal urinary function proile (combining sonographic
and biochemical predictors) is most useful clinically in
selecting the fetus that will beneit from in utero
intervention.
• Examination of fetal genitalia plays a key role in the
diagnostic workup of many structural abnormalities and
genetic disorders, as well as in the assessment of multiple
pregnancies.
CHAPTER OUTLINE
THE NORMAL URINARY TRACT
Embryology
Sonographic Appearance
Amniotic Fluid Volume
URINARY TRACT ABNORMALITIES
Bilateral Renal Agenesis
Unilateral Renal Agenesis
Renal Ectopia
Horseshoe Kidney
Renal Cystic Disease
Multicystic Dysplastic Kidney
Obstructive Cystic Renal Dysplasia
Autosomal Recessive Polycystic
Kidney Disease
Autosomal Dominant Polycystic
Kidney Disease
Syndromes Associated With Renal
Cystic Disease
Hyperechogenic Kidneys
Renal Neoplasm
Adrenal Mass
Upper Urinary Tract Dilation
Ureteropelvic Junction Obstruction
Vesicoureteral Junction Obstruction
and Primary Megaureter
Duplication Anomalies
Vesicoureteral Relux
Lower Urinary Tract Obstruction
In Utero Intervention: Fetal
Vesicoamniotic Shunting and
Cystoscopy
Nonvisualized Bladder
Bladder Exstrophy
THE GENITAL TRACT
Normal Genitalia
Abnormal Genitalia
Hydrocolpos
Ovarian Cysts
CONCLUSION
Acknowledgments
Evaluation of the fetal urogenital tract is an integral part of
the obstetric ultrasound examination. Sonography depicts
normal developmental anatomy and allows detection and
characterization of many genitourinary abnormalities. In addition,
assessment of the amniotic luid volume (AFV) oten provides
important prognostic information regarding fetal renal function.
Accurate and early prenatal diagnosis is important because this
may inluence obstetric and neonatal management.
Congenital anomalies of the kidney and urinary tract (CAKUT)
account for approximately 30% of all malformations detected on
routine prenatal sonography. 1,2 A systematic sonographic approach
is proposed, which includes a search for associated anomalies
and detailed evaluation of renal structure and function.
THE NORMAL URINARY TRACT
Embryology
he permanent kidney (metanephros) is the third in a series
of excretory organs in the human embryo, forming ater the
pronephros and mesonephros. 3 In the seventh menstrual week,
the metanephros begins to develop from two sources: the
metanephric diverticulum (ureteric bud) and the metanephric
mass of intermediate mesoderm (Fig. 39.1). he ureteric bud
is an outgrowth from the mesonephric duct, near its entrance
into the cloaca. It elongates and branches in a dichotomous
pattern, giving rise to the ureter, renal pelvis, calyces, and
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