- Email: [email protected]
Prenatal diagnosis of fetal urinary pathology with ultrasound
European Journal of Obstetrics & Gynecology and Reproductive Biology 52 (1993) 169- 174
Prenatal diagnosis of fetal urinary pathology with ultrasound Asterios
Korantzis, ‘Euromedica’
Emmanuel
Dlagnostir
Center.
Cardamaki?, 2-4 Me.rogion
Constantin
Ave.. GR-I I5 27 Athens.
Apostolidis Grec~
(Accepted 14 September 1993)
Abstract Forty-six cases of fetal urinary malformations diagnosed by ultrasound are described. A reliable prenatal diagnosis is extremely important since it may offer options for pregnancy termination or may change obstetric management in
the third trimester. Ultrasound criteria necessary for the diagnosis are: (i) bilateral multicystic kidneys, (ii) loss of renal architecture, (iii) non-visualization of the fetal bladder, (iv) absence of amniotic fluid, and (v) urinary dilatation. Thirty-six of the 46 cases of fetal urinary pathology had postnatal confirmation of the diagnosis. No false positive diagnosis was observed. All 19 fetuses with obstructive uropathy were observed for more than 3 weeks. Postnatal function was normal in 12 (63%) fetuses with obstructive detection of fetal urinary pathology. Key
words:
Prenatal
diagnosis;
Renal agenesis;
uropathy.
Multicystic
1. Introduction Targeted fetal ultrasonography to detect fetal anomalies is traditionally performed in the middle of the second trimester [I]. The urinary tract is an ideal candidate for early prenatal diagnosis by ultrasound. With the increasing use of ultrasonography in pregnancy, fetal anomahes are detected at earlier in gestation. Kidneys can be detected from the 12th week of pregnancy and after the 18th week it is possible to detect anatomical malformations [2]. A reliable prenatal diagnosis is extremely impor-
* Corresponding author. ParaskeviiAthens Greece.
29 Aheon str., CR-153 43 Ag.
It is concluded
kidney;
that ultrasound
Hydronephrosis;
is a valuable
Megaureter;
Ectopic
tool in the
kidney
tant since it may offer options for pregnancy termination or may change obstetric management in the third trimester. In an effort to test the hypothesis that a reliable prenatal diagnosis can be made by ultrasound, this report reviews our experience during a 7-year period in the diagnosis of fetal urinary pathology. 2. Material and methods From January 1985 to June 20, 1992, 46 fetuses were diagnosed as having urinary pathology out of 8025 ultrasound scans performed in the obstetric population (0.57%). Thirty-six of the 46 fetuses with urinary pathology had postnatal contirmation of the diagnosis. Sonographic examinations were performed with
002%2243193/$06.00 0 1993 Elsevier Science Ireland Ltd. All rights reserved SSDI 0028-2243(93)01697-R
A. Korantzis er al. /Eur. J. Obsret. Gynecol. Reprod. Biol. 52 (1993) 169-174
170
linear array real-time equipment with a 3.5MHz transducer (Toshiba 77B and 100A). Our prenatal diagnosis was based on the ultrasound findings of (i) bilateral multicystic abdominal masses, (ii) loss of normal renal architecture, (iii) failure to visualize the fetal bladder, (iv) absence of amniotic fluid, (v) urinary dilatation, and (vi) failure to identify fetal kidneys. Between 12and 17-weeks gestational age, transversal sections were performed and after 17- weeks gestational age three kinds of sections [3] (transversal, paraspinal longitudinal and prespinal frontal) were performed. Fig. 2. Longitudinal paraspinal scan through fetal abdomen. The right megaureter is seen at the bottom of the figure (arrow). Note the decreased amniotic fluid. RK, right kidney.
3. Results The following results were obtained:
(9 (ii) (iii) (iv)
;:I, (vii) (viii)
bilateral renal agenesis in 4 fetuses; monolateral multicystic kidney disease (Potter IIA) in 9 fetuses; bilateral multicystic kidney disease (Potter II*) in 6 fetuses; monolateral hydronephrosis in 8 fetuses (Fig. 1); megaureter in 2 fetuses (Fig. 2); urethral obstruction in 4 fetuses (Fig. 3); bilateral hydronephrosis in 5 fetuses; ectopic wrinkled kidney in 3 fetuses;
Fig. 1. Typical
image of hydronephrosis (left). RK, right kidney; SP, spine; LK, left kidney.
(ix) presence of a great cyst in the kidney in 3 fetuses (Fig.4); and (x) infantile bilateral polycystic kidneys in 2 fetuses (Fig. 5). The sonographic diagnosis of bilateral renal agenesis was based on non-visualization of the bladder, in the severe oligohydramnios and in the absence of kidneys. Oligohydramnios was present in all cases of bilateral renal agenesis. In 2 fetuses the absence of
Fig. 3. Longitudinal and transverse scan demonstrating nose (N), mouth (M), umbilical cord (UC) and dilated bladder (crosses) due to urethral atresia in a fetus of I4 weeks.
A. Korantzis et al. /Eur. J. Obstet. Gynecol. Reprod. Biol. 52 (1993)
169-174
Fig. 4. Longitudinal (left) and transverse (right) scan revealing significant cyst (arrows) on the right kidney at 36 weeks. RK. right kidney; LK, left kidney.
Fig. 6. Transverse scan (right) of fetal abdomen of enlarged left multicystic kidney and in the left side of the figure is shown the Doppler examination of the left renal artery with PI = 1.67 (decreased resistance). PI, pulsatility index.
kidneys was promptly diagnosed. In the remaining 2 fetuses enlargement of the adrenal glands made the diagnosis of the absence of kidneys doubtful. On repeated ultrasounds, failure to identify consistent imaging of the renal architecture made the bilateral renal agenesis evident. In all cases, repeated ultrasounds (after 30 min) failed to visualize the fetal bladder. In all cases the diagnosis was made prior to 25 weeks of gestation. Three women were submitted to elective termination of pregnancy. One woman delivered at 40 weeks and at autopsy the adrenal glands were found to be enlarged weighing 16.5 g (left) and 10.2 g (right) (normal
Fig. 5. Transverse scan by crosses correspond hyperechogenicity and at
of fetal abdomen. The kidneys indicated to infantile polycystic kidneys. Note the the sponge morphology of the kidneys 20 weeks. SP. spine.
171
combined fetal adrenal weight at 40 weeks’ gestation is 8.5 g) [4]. Also included in our series are 15 fetuses with multicystic kidney disease Potter IIA, of which 9 were monolateral. The diagnosis of monolateral multicystic kidney disease was based on the morphology of the affected kidney. In all 9 cases the kidney was enlarged and occupied the greater part of the abdomen. The affected kidney presented lo- 15 cysts of variable size, clearly distinguishable, which did not communicate with the renal pelvis. In 5 out of 9 cases the diagnosis was made from the first ultrasound (2 were presented in the 17th week of pregnancy and the remaining 3 in the 20th week of pregnancy). In all 5 cases the other kidney was completely normal. In the remaining 4 cases the first ultrasound was performed between the 16th and 18th week of pregnancy. In 3 cases the affected kidney did not present the above mentioned morphology of polycystic kidney; however, hydronephrosis was present and we advised ultrasound follow-up every week. On the 25th week of pregnancy the typical morphology of polycystic kidney had developed. It is interesting to note that the Doppler examination of the left renal artery at 25 and 33 weeks of gestation presented decreased resistance (Fig. 6). The otner kidney was completely normal. The last fetus, with monolateral multicystic kidney, presented with the left multicystic kidney and the right kidney with
172
A. Korantzis et al. /Eur.
hydronephrosis, a diagnosis which led to the conclusion that the management of this pregnancy would be troublesome. Pathologic confirmation was not available in these cases, since operations were not performed to remove the affected kidney. The diagnosis of bilateral multicystic kidney disease was made in all 6 fetuses before the 24th week of gestation and was based on the morphology of the kidneys, severe oligohydramnios, and on the non-visualization of the fetal bladder. With one exception, all patients elected to terminate the pregnancy. Autopsy information was available in four of the six cases and in all four the prenatal diagnosis had been confirmed. Associated congenital anomalies were not noted by ultrasound in these patients. In the one patient who decided to deliver, we performed a Doppler examination in both renal arteries at 33 weeks of gestation. Both renal arteries presented decreased resistance. The oligohydramnios and non-visualization of the fetal bladder were also present in 2 fetuses with bilateral infantile polycystic kidneys. The kidneys were enlarged solid masses, and presented micropolycystic (without interfaces among the cystic masses) homogeneous, hyperechogenic morphology. The enlargement of the kidneys was observed in the second trimester without any other sign. We advised sonographic follow-up, and at the 24th week of gestation severe oligohydramnios and failure to visualize the fetal bladder had developed. The three fetuses with ectopic wrinkled kidneys were female and the ectopic kidney was present in observe other the pelvis. We did not sonographically detectable abnormalities. The last population of our series included 19 fetuses with dilatation of urinary tract (monolateral hydronephrosis in 8, bilateral hydronephrosis in 5, urethral obstruction in 4 and megaureter in 2). In two cases with monolateral hydronephrosis the renal pelvis was enlarged (indicating subpelvic obstruction). In the remaining 8 cases the homolateral ureter was also enlarged (indicating that the obstruction was present in the ureter). In this population it is interesting to mention two fetuses with idiopathic megaureter without en-
J. Obslel. Gynecol. Reprod. Biol. 52 (1993) 169-174
largement of the renal pelvis. In the five cases of bilateral hydronephrosis, enlarged fetal bladder indicating urethral obstruction was not observed. Fetal bladder outlet obstruction with enlarged fetal bladder, thick bladder wall, bilateral ureter enlargement and bilateral enlargement of the renal pelvis was present in three male fetuses (posterior urethral valves) and in one female fetus (urethral atresia). In the present series we did not report the cases with functional hydronephrosis (steady or regressive dilatation of urinary system). Fifteen cases with obstructive uropathy were diagnosed by ultrasound early in the second trimester. No associated anomalies, detected by ultrasound, were observed. The renal parenchymal structure also presented dilatation of the calices and narrowing of cortical thickness, and the amniotic fluid was reduced in one case of obstructive uropathy. The postnatal outcome shows that surgical treatment was necessary in 7 cases and postnatal renal function was normal in 12 fetuses with obstructive uropathy. 4. Discussion In all cases of our series the sonographic diagnosis was relatively difficult and demanded repeated ultrasounds. As with any form of prenatal diagnosis, the importance of accuracy in diagnosis cannot be overstated. In bilateral renal agenesis, such as bilateral multicystic kidney disease, a reliable prenatal diagnosis is extremely important. False positive diagnosis could result in elective terminations of pregnancy or in suboptimal management of viable unaffected infants [5]. False negative diagnosis could result in an unnecessary cesarean section, not infrequently performed because of intraparturn fetal distress or malpresentation of infants with bilateral renal agenesis [6]. When the diagnosis of bilateral multicystic kidney disease is entertained, one must also consider infantile polycystic kidney disease. Both bilateral multicystic kidney disease and infantile polycystic kidney disease are associated with loss of normal renal architecture, absence of amniotic fluid and absence of fetal bladder on ul-
A.
Koran(zis
et
a[. /Eur.
J.
Obsret. Gynecol. Reprod.
Bid 52 (19931169-174
trasound examination [7]. The kidneys in infantile polycystic kidney disease are enlarged solid masses and present a micropolycystic (without interfaces among the cystic masses), homogeneous and hyperechogenic morphology. It should be noted, however, that in the early stages of infantile polycystic kidney disease the kidney size may be normal and amniotic fluid may be present [8]. The kidneys in multicystic kidney disease are enlarged (Potter II,) and present numerous (10-15) cysts of variable size with interfaces among the cystic masses, which do not communicate with the renal pelvis. Bilateral renal agenesis seems to be transmitted in a polygenic pattern with a suggested recurrence rate of 2-5O/u [5]. This recurrence rate is higher (12.5%) if there are more congenital anomalies in other organs [9]. Enlargement of the adrenal glands as a potential source of confusion has been previously recognized in both fetuses and neonates [9, lo]. Potter [ 1l] has suggested that the adrenal glands in bilateral renal agenesis adopt an oval disk shape, presumably because of the absence of a compressive effect by the normal kidney. This shape can grossly simulate the morphology of a normal fetal kidney. The most helpful criteria in distinguishing between the two organs include consistent imaging of the renal pelvis and clear identification of the renal capsule [5]. The proposed diagnostic criteria for bilateral renal agenesis include non-visualization of fetal bladder, severe oligohydramnios and absence of the kidneys. It seems that repeated and consistent nonvisualization of the fetal bladder is a reliable sign of in utero failure to produce urine (in the absence of urinary obstruction). A fetal bladder is easy to identify and should be demonstrated in every sonographic examination after 16 weeks of gestation [5]. Its absence should prompt further investigation of the kidneys. Absent kidneys suggest bilateral renal agenesis; hyperechogenic enlarged kidneys would suggest infantile polycystic kidney disease; and enlarged kidneys with numerous echo-free areas (cysts) suggest multicystic kidney disease.
173
Oligohydramnios, presented in 17 cases of our series, is thought to result from lack of production of fetal urine, an important component of amniotic fluid [5]. It is interesting to note that oligohydramnios was usually found later than the other signs of fetal uropathy (around the 20th week). This could be explained by the fact that prior to 20 weeks gestation the contribution of fetal urine to amniotic fluid is small [12] and therefore it is possible that oligohydramnios is not invariably present in fetal uropathy in the early mid-trimester. Hydronephrosis, due to obstruction, can usually be clearly differentiated from multicystic kidney disease [ 131. Particular attention, however, must be paid to the renal architecture and identification of the renal pelvis. We found the following criteria useful for the diagnosis of obstructive uropathy and the determination of the site of obstruction: (i) renal pelvis enlarged (subpelvic obstruction), (ii) enlarged renal pelvis and ureter (ureteral obstruction), (iii) enlarged fetal bladder with thick bladder wall, bilateral ureter enlargement and bilateral enlargement of renal pelvis (fetal bladder outlet obstruction), and (iv) dilatation of calices and narrowing of cortical thickness. In conclusion, an accurate prenatal diagnosis of fetal uropathy can be made with high-resolution ultrasonographic equipment and transvaginal ultrasonography. It is important for the obstetrician to be aware of the appearance of the anomalies to allow optimal management for the patients (pregnant women, fetuses and neonates). 5. References Stiller R. Early ultrasonic appearance of fetal bladder outlet obstruction. Am J Obstet Gynecol 1989; 160: 584-585. Hobbins JC, Grannum P, Berkowitz R et al. Ultrasounds in the diagnosis of congenital anomalies. Am _I Obstet Gynecol 1979; 134: 331-345. dell’Agnola CA, Ferrazzi E. Cargiulo M. Cabibbe G, Brinbati B. Nicolini U. Difficulties in ‘real time’ ultrasound diagnosis of fetal urological anomalies. Z Kinderchir 1982; 37: 34. Gruenwald P, Minh H. Evaluation of body and organ weights in perinatal pathology. I. Normal standards derived from autopsies. Am J Clin Pathol 1960; 34: 247. Romero R. Cullen M, &annum P et al. Antenatal diaynosis of renal anomalies with ultrasound. 111. Bilateral renal agenesis. Am J Obsret Gynecol 1985: 151: 38-43.
174 6
7
8
9
A. Korantzis et al. /Eur.
Ratten GJ, Beischer NA, Fortune DW. Obstetric complications when the fetus has Potter’s syndrome I. Clinical considerations. Am J Obstet Gynecol 1973; 115:890. D’Alton M, Romero R, &annum P, DePalma L, Jeanty P, Hobbins J. Antenatal diagnosis of renal anomalies with ultrasound. IV. Bilateral multicystic kidney disease. Am J Obstet Gynecol 1986; 154: 532-537. Romero R, Cullen M, Jeanty P et al. The diagnosis of congenital renal anomalies with ultrasound. IV. Infantile polycystic kidney disease. Am J Obstet Gynecol 1984; 150: 259. Dubbins PA, Kutz AB, Wapner RJ, Goldberg BB. Renal agenesis: spectrum of in utero findings. JCU 198I, 9: 189.
J. Obstet. Gyneeol. Reprod. Biol. 52 (1993)
169-174
IO Silverman PM, Carrolli BA, Moskowitz PS. Adrenal sonography in renal agenesis and dysplasia. AJR 1980; 134: 600. I I Potter EL. Extrinsic abnormalities of kidneys in normal and abnormal development of the kidney. Chicago: Year Book Medical Publishers, 1972: 83. I2 Saunders P, Rhodes P. The origin and circulation of the amniotic fluid. In: Fairweather DVI, Eskes TKAB, eds. Amniotic fluid, research and clinical application. Amsterdam: Excerpta Medica, 1975: I. I3 Stuck KJ, Koff SA, Silver TM. Ultrasonic features of multicystic dysplastic kidney: expanded diagnostic criteria. Radiology 1982; 143: 217.
Prenatal diagnosis of fetal urinary pathology with ultrasound Asterios
Korantzis, ‘Euromedica’
Emmanuel
Dlagnostir
Center.
Cardamaki?, 2-4 Me.rogion
Constantin
Ave.. GR-I I5 27 Athens.
Apostolidis Grec~
(Accepted 14 September 1993)
Abstract Forty-six cases of fetal urinary malformations diagnosed by ultrasound are described. A reliable prenatal diagnosis is extremely important since it may offer options for pregnancy termination or may change obstetric management in
the third trimester. Ultrasound criteria necessary for the diagnosis are: (i) bilateral multicystic kidneys, (ii) loss of renal architecture, (iii) non-visualization of the fetal bladder, (iv) absence of amniotic fluid, and (v) urinary dilatation. Thirty-six of the 46 cases of fetal urinary pathology had postnatal confirmation of the diagnosis. No false positive diagnosis was observed. All 19 fetuses with obstructive uropathy were observed for more than 3 weeks. Postnatal function was normal in 12 (63%) fetuses with obstructive detection of fetal urinary pathology. Key
words:
Prenatal
diagnosis;
Renal agenesis;
uropathy.
Multicystic
1. Introduction Targeted fetal ultrasonography to detect fetal anomalies is traditionally performed in the middle of the second trimester [I]. The urinary tract is an ideal candidate for early prenatal diagnosis by ultrasound. With the increasing use of ultrasonography in pregnancy, fetal anomahes are detected at earlier in gestation. Kidneys can be detected from the 12th week of pregnancy and after the 18th week it is possible to detect anatomical malformations [2]. A reliable prenatal diagnosis is extremely impor-
* Corresponding author. ParaskeviiAthens Greece.
29 Aheon str., CR-153 43 Ag.
It is concluded
kidney;
that ultrasound
Hydronephrosis;
is a valuable
Megaureter;
Ectopic
tool in the
kidney
tant since it may offer options for pregnancy termination or may change obstetric management in the third trimester. In an effort to test the hypothesis that a reliable prenatal diagnosis can be made by ultrasound, this report reviews our experience during a 7-year period in the diagnosis of fetal urinary pathology. 2. Material and methods From January 1985 to June 20, 1992, 46 fetuses were diagnosed as having urinary pathology out of 8025 ultrasound scans performed in the obstetric population (0.57%). Thirty-six of the 46 fetuses with urinary pathology had postnatal contirmation of the diagnosis. Sonographic examinations were performed with
002%2243193/$06.00 0 1993 Elsevier Science Ireland Ltd. All rights reserved SSDI 0028-2243(93)01697-R
A. Korantzis er al. /Eur. J. Obsret. Gynecol. Reprod. Biol. 52 (1993) 169-174
170
linear array real-time equipment with a 3.5MHz transducer (Toshiba 77B and 100A). Our prenatal diagnosis was based on the ultrasound findings of (i) bilateral multicystic abdominal masses, (ii) loss of normal renal architecture, (iii) failure to visualize the fetal bladder, (iv) absence of amniotic fluid, (v) urinary dilatation, and (vi) failure to identify fetal kidneys. Between 12and 17-weeks gestational age, transversal sections were performed and after 17- weeks gestational age three kinds of sections [3] (transversal, paraspinal longitudinal and prespinal frontal) were performed. Fig. 2. Longitudinal paraspinal scan through fetal abdomen. The right megaureter is seen at the bottom of the figure (arrow). Note the decreased amniotic fluid. RK, right kidney.
3. Results The following results were obtained:
(9 (ii) (iii) (iv)
;:I, (vii) (viii)
bilateral renal agenesis in 4 fetuses; monolateral multicystic kidney disease (Potter IIA) in 9 fetuses; bilateral multicystic kidney disease (Potter II*) in 6 fetuses; monolateral hydronephrosis in 8 fetuses (Fig. 1); megaureter in 2 fetuses (Fig. 2); urethral obstruction in 4 fetuses (Fig. 3); bilateral hydronephrosis in 5 fetuses; ectopic wrinkled kidney in 3 fetuses;
Fig. 1. Typical
image of hydronephrosis (left). RK, right kidney; SP, spine; LK, left kidney.
(ix) presence of a great cyst in the kidney in 3 fetuses (Fig.4); and (x) infantile bilateral polycystic kidneys in 2 fetuses (Fig. 5). The sonographic diagnosis of bilateral renal agenesis was based on non-visualization of the bladder, in the severe oligohydramnios and in the absence of kidneys. Oligohydramnios was present in all cases of bilateral renal agenesis. In 2 fetuses the absence of
Fig. 3. Longitudinal and transverse scan demonstrating nose (N), mouth (M), umbilical cord (UC) and dilated bladder (crosses) due to urethral atresia in a fetus of I4 weeks.
A. Korantzis et al. /Eur. J. Obstet. Gynecol. Reprod. Biol. 52 (1993)
169-174
Fig. 4. Longitudinal (left) and transverse (right) scan revealing significant cyst (arrows) on the right kidney at 36 weeks. RK. right kidney; LK, left kidney.
Fig. 6. Transverse scan (right) of fetal abdomen of enlarged left multicystic kidney and in the left side of the figure is shown the Doppler examination of the left renal artery with PI = 1.67 (decreased resistance). PI, pulsatility index.
kidneys was promptly diagnosed. In the remaining 2 fetuses enlargement of the adrenal glands made the diagnosis of the absence of kidneys doubtful. On repeated ultrasounds, failure to identify consistent imaging of the renal architecture made the bilateral renal agenesis evident. In all cases, repeated ultrasounds (after 30 min) failed to visualize the fetal bladder. In all cases the diagnosis was made prior to 25 weeks of gestation. Three women were submitted to elective termination of pregnancy. One woman delivered at 40 weeks and at autopsy the adrenal glands were found to be enlarged weighing 16.5 g (left) and 10.2 g (right) (normal
Fig. 5. Transverse scan by crosses correspond hyperechogenicity and at
of fetal abdomen. The kidneys indicated to infantile polycystic kidneys. Note the the sponge morphology of the kidneys 20 weeks. SP. spine.
171
combined fetal adrenal weight at 40 weeks’ gestation is 8.5 g) [4]. Also included in our series are 15 fetuses with multicystic kidney disease Potter IIA, of which 9 were monolateral. The diagnosis of monolateral multicystic kidney disease was based on the morphology of the affected kidney. In all 9 cases the kidney was enlarged and occupied the greater part of the abdomen. The affected kidney presented lo- 15 cysts of variable size, clearly distinguishable, which did not communicate with the renal pelvis. In 5 out of 9 cases the diagnosis was made from the first ultrasound (2 were presented in the 17th week of pregnancy and the remaining 3 in the 20th week of pregnancy). In all 5 cases the other kidney was completely normal. In the remaining 4 cases the first ultrasound was performed between the 16th and 18th week of pregnancy. In 3 cases the affected kidney did not present the above mentioned morphology of polycystic kidney; however, hydronephrosis was present and we advised ultrasound follow-up every week. On the 25th week of pregnancy the typical morphology of polycystic kidney had developed. It is interesting to note that the Doppler examination of the left renal artery at 25 and 33 weeks of gestation presented decreased resistance (Fig. 6). The otner kidney was completely normal. The last fetus, with monolateral multicystic kidney, presented with the left multicystic kidney and the right kidney with
172
A. Korantzis et al. /Eur.
hydronephrosis, a diagnosis which led to the conclusion that the management of this pregnancy would be troublesome. Pathologic confirmation was not available in these cases, since operations were not performed to remove the affected kidney. The diagnosis of bilateral multicystic kidney disease was made in all 6 fetuses before the 24th week of gestation and was based on the morphology of the kidneys, severe oligohydramnios, and on the non-visualization of the fetal bladder. With one exception, all patients elected to terminate the pregnancy. Autopsy information was available in four of the six cases and in all four the prenatal diagnosis had been confirmed. Associated congenital anomalies were not noted by ultrasound in these patients. In the one patient who decided to deliver, we performed a Doppler examination in both renal arteries at 33 weeks of gestation. Both renal arteries presented decreased resistance. The oligohydramnios and non-visualization of the fetal bladder were also present in 2 fetuses with bilateral infantile polycystic kidneys. The kidneys were enlarged solid masses, and presented micropolycystic (without interfaces among the cystic masses) homogeneous, hyperechogenic morphology. The enlargement of the kidneys was observed in the second trimester without any other sign. We advised sonographic follow-up, and at the 24th week of gestation severe oligohydramnios and failure to visualize the fetal bladder had developed. The three fetuses with ectopic wrinkled kidneys were female and the ectopic kidney was present in observe other the pelvis. We did not sonographically detectable abnormalities. The last population of our series included 19 fetuses with dilatation of urinary tract (monolateral hydronephrosis in 8, bilateral hydronephrosis in 5, urethral obstruction in 4 and megaureter in 2). In two cases with monolateral hydronephrosis the renal pelvis was enlarged (indicating subpelvic obstruction). In the remaining 8 cases the homolateral ureter was also enlarged (indicating that the obstruction was present in the ureter). In this population it is interesting to mention two fetuses with idiopathic megaureter without en-
J. Obslel. Gynecol. Reprod. Biol. 52 (1993) 169-174
largement of the renal pelvis. In the five cases of bilateral hydronephrosis, enlarged fetal bladder indicating urethral obstruction was not observed. Fetal bladder outlet obstruction with enlarged fetal bladder, thick bladder wall, bilateral ureter enlargement and bilateral enlargement of the renal pelvis was present in three male fetuses (posterior urethral valves) and in one female fetus (urethral atresia). In the present series we did not report the cases with functional hydronephrosis (steady or regressive dilatation of urinary system). Fifteen cases with obstructive uropathy were diagnosed by ultrasound early in the second trimester. No associated anomalies, detected by ultrasound, were observed. The renal parenchymal structure also presented dilatation of the calices and narrowing of cortical thickness, and the amniotic fluid was reduced in one case of obstructive uropathy. The postnatal outcome shows that surgical treatment was necessary in 7 cases and postnatal renal function was normal in 12 fetuses with obstructive uropathy. 4. Discussion In all cases of our series the sonographic diagnosis was relatively difficult and demanded repeated ultrasounds. As with any form of prenatal diagnosis, the importance of accuracy in diagnosis cannot be overstated. In bilateral renal agenesis, such as bilateral multicystic kidney disease, a reliable prenatal diagnosis is extremely important. False positive diagnosis could result in elective terminations of pregnancy or in suboptimal management of viable unaffected infants [5]. False negative diagnosis could result in an unnecessary cesarean section, not infrequently performed because of intraparturn fetal distress or malpresentation of infants with bilateral renal agenesis [6]. When the diagnosis of bilateral multicystic kidney disease is entertained, one must also consider infantile polycystic kidney disease. Both bilateral multicystic kidney disease and infantile polycystic kidney disease are associated with loss of normal renal architecture, absence of amniotic fluid and absence of fetal bladder on ul-
A.
Koran(zis
et
a[. /Eur.
J.
Obsret. Gynecol. Reprod.
Bid 52 (19931169-174
trasound examination [7]. The kidneys in infantile polycystic kidney disease are enlarged solid masses and present a micropolycystic (without interfaces among the cystic masses), homogeneous and hyperechogenic morphology. It should be noted, however, that in the early stages of infantile polycystic kidney disease the kidney size may be normal and amniotic fluid may be present [8]. The kidneys in multicystic kidney disease are enlarged (Potter II,) and present numerous (10-15) cysts of variable size with interfaces among the cystic masses, which do not communicate with the renal pelvis. Bilateral renal agenesis seems to be transmitted in a polygenic pattern with a suggested recurrence rate of 2-5O/u [5]. This recurrence rate is higher (12.5%) if there are more congenital anomalies in other organs [9]. Enlargement of the adrenal glands as a potential source of confusion has been previously recognized in both fetuses and neonates [9, lo]. Potter [ 1l] has suggested that the adrenal glands in bilateral renal agenesis adopt an oval disk shape, presumably because of the absence of a compressive effect by the normal kidney. This shape can grossly simulate the morphology of a normal fetal kidney. The most helpful criteria in distinguishing between the two organs include consistent imaging of the renal pelvis and clear identification of the renal capsule [5]. The proposed diagnostic criteria for bilateral renal agenesis include non-visualization of fetal bladder, severe oligohydramnios and absence of the kidneys. It seems that repeated and consistent nonvisualization of the fetal bladder is a reliable sign of in utero failure to produce urine (in the absence of urinary obstruction). A fetal bladder is easy to identify and should be demonstrated in every sonographic examination after 16 weeks of gestation [5]. Its absence should prompt further investigation of the kidneys. Absent kidneys suggest bilateral renal agenesis; hyperechogenic enlarged kidneys would suggest infantile polycystic kidney disease; and enlarged kidneys with numerous echo-free areas (cysts) suggest multicystic kidney disease.
173
Oligohydramnios, presented in 17 cases of our series, is thought to result from lack of production of fetal urine, an important component of amniotic fluid [5]. It is interesting to note that oligohydramnios was usually found later than the other signs of fetal uropathy (around the 20th week). This could be explained by the fact that prior to 20 weeks gestation the contribution of fetal urine to amniotic fluid is small [12] and therefore it is possible that oligohydramnios is not invariably present in fetal uropathy in the early mid-trimester. Hydronephrosis, due to obstruction, can usually be clearly differentiated from multicystic kidney disease [ 131. Particular attention, however, must be paid to the renal architecture and identification of the renal pelvis. We found the following criteria useful for the diagnosis of obstructive uropathy and the determination of the site of obstruction: (i) renal pelvis enlarged (subpelvic obstruction), (ii) enlarged renal pelvis and ureter (ureteral obstruction), (iii) enlarged fetal bladder with thick bladder wall, bilateral ureter enlargement and bilateral enlargement of renal pelvis (fetal bladder outlet obstruction), and (iv) dilatation of calices and narrowing of cortical thickness. In conclusion, an accurate prenatal diagnosis of fetal uropathy can be made with high-resolution ultrasonographic equipment and transvaginal ultrasonography. It is important for the obstetrician to be aware of the appearance of the anomalies to allow optimal management for the patients (pregnant women, fetuses and neonates). 5. References Stiller R. Early ultrasonic appearance of fetal bladder outlet obstruction. Am J Obstet Gynecol 1989; 160: 584-585. Hobbins JC, Grannum P, Berkowitz R et al. Ultrasounds in the diagnosis of congenital anomalies. Am _I Obstet Gynecol 1979; 134: 331-345. dell’Agnola CA, Ferrazzi E. Cargiulo M. Cabibbe G, Brinbati B. Nicolini U. Difficulties in ‘real time’ ultrasound diagnosis of fetal urological anomalies. Z Kinderchir 1982; 37: 34. Gruenwald P, Minh H. Evaluation of body and organ weights in perinatal pathology. I. Normal standards derived from autopsies. Am J Clin Pathol 1960; 34: 247. Romero R. Cullen M, &annum P et al. Antenatal diaynosis of renal anomalies with ultrasound. 111. Bilateral renal agenesis. Am J Obsret Gynecol 1985: 151: 38-43.
174 6
7
8
9
A. Korantzis et al. /Eur.
Ratten GJ, Beischer NA, Fortune DW. Obstetric complications when the fetus has Potter’s syndrome I. Clinical considerations. Am J Obstet Gynecol 1973; 115:890. D’Alton M, Romero R, &annum P, DePalma L, Jeanty P, Hobbins J. Antenatal diagnosis of renal anomalies with ultrasound. IV. Bilateral multicystic kidney disease. Am J Obstet Gynecol 1986; 154: 532-537. Romero R, Cullen M, Jeanty P et al. The diagnosis of congenital renal anomalies with ultrasound. IV. Infantile polycystic kidney disease. Am J Obstet Gynecol 1984; 150: 259. Dubbins PA, Kutz AB, Wapner RJ, Goldberg BB. Renal agenesis: spectrum of in utero findings. JCU 198I, 9: 189.
J. Obstet. Gyneeol. Reprod. Biol. 52 (1993)
169-174
IO Silverman PM, Carrolli BA, Moskowitz PS. Adrenal sonography in renal agenesis and dysplasia. AJR 1980; 134: 600. I I Potter EL. Extrinsic abnormalities of kidneys in normal and abnormal development of the kidney. Chicago: Year Book Medical Publishers, 1972: 83. I2 Saunders P, Rhodes P. The origin and circulation of the amniotic fluid. In: Fairweather DVI, Eskes TKAB, eds. Amniotic fluid, research and clinical application. Amsterdam: Excerpta Medica, 1975: I. I3 Stuck KJ, Koff SA, Silver TM. Ultrasonic features of multicystic dysplastic kidney: expanded diagnostic criteria. Radiology 1982; 143: 217.