B超检查胎儿肾脏回声增强的临床意义

目的探讨B超检查胎儿肾脏回声增强的临床意义。方法选择31例产前B超发现胎儿肾脏回声增强的患者,征求本人意见,对选择引产放弃胎儿者（12例）行引产后患儿尸体解剖;对选择继续妊娠者（19例）定期随访。分娩时取胎儿脐带血进行胎儿染色体分析。结果（1）31例中6例胎儿同时合并其他脏器异常,3例胎儿合并染色体异常,2例患者具有家族史。（2）12例选择终止妊娠者中,10例伴羊水过少;B超检查胎儿肾脏回声增强的原因分别为婴儿型多囊肾10例、成人型多囊肾1例和多囊性肾发育不良1例。（3）19例选择继续妊娠者中,2例羊水过少患儿于新生儿期死亡,病理解剖结果为婴儿型多囊肾;3例患儿分别在出生后1岁内死亡,病理诊断分别为婴儿型多囊肾或多囊性肾发育不良;1例患儿在出生后26个月出现高血压症状,肾功能异常,诊断为婴儿型多囊肾;4例患儿出生后B超检查肾脏回声转为正常;9例肾脏B超表现与产前检查相同,但目前没有任何临床症状。结论（1）胎儿期肾脏B超回声增强的原因多为婴儿型多囊肾、肾发育不良和非特异性肾病,也有部分为正常肾脏变异。（2）羊水量是判断胎儿预后的关键指标之一,当胎儿期肾脏回声增强伴羊水过少时提示胎儿预后不良。（3）当发现肾脏B超回声增强时,应仔细询问家族史,并对胎儿父母肾脏及胎儿其他部位进行详细检查,必要时建议进行胎儿染色体核型分析。     

A tale of two prior probabilities--avoiding the false positive antenatal diagnosis of autosomal recessive polycystic kidney disease.

We describe a case in which the typical ultrasound diagnosis of infantile polycystic kidney in a woman with no family history of renal disease was not confirmed by histology following termination of the pregnancy. This is contrasted with the situation in another couple who were known carriers of autosomal recessive polycystic kidney disease and where the prenatal ultrasound diagnosis was confirmed histologically. When prior genetic risk is low, the possibility of a normal or less severe outcome must be discussed with parents when fetal ultrasound shows large, echogenic kidneys but normal amniotic fluid volume.     

Fetal serum ss2-microglobulin and cystatin C in the prediction of post-natal renal function in bilateral hypoplasia and hyperechogenic enlarged kidneys

OBJECTIVES: To evaluate fetal serum ss2-microglobulin and cystatin C in the prediction of post-natal renal function in bilateral hypoplasia and hyperechogenic enlarged kidneys. Predicting post-natal renal function is crucial to the prenatal evaluation of fetal nephropathies. Prenatal ultrasound can identify terminal renal failure, but is not sensitive enough to identify infants whose post-natal renal function will be impaired. Fetal serum ss2-microglobulin and cystatin C are potential predictors of post-natal renal function. METHODS: Fifty-four prenatally diagnosed cases of bilateral nephropathy were retrospectively reviewed. Final diagnosis was established using histological or post-natal findings: renal hypoplasia (n = 7), cystic dysplasia (n = 9), autosomal dominant polycystic kidney disease (ADPKD; n = 8) or autosomal recessive polycystic kidney disease (ARPKD; n = 22) and transient sonographic abnormalities (n = 8). Fetal serum ss2-microglobulin and cystatin C were assayed respectively in 54 and 38 cases. The prognostic value of these markers was assessed in terms of the post-natal outcome. RESULTS: In bilateral kidney hypoplasia and cystic dysplasia, ss2-microglobulin and cystatin C were significantly (p < 0.0001 and p < 0.02 respectively) higher than in the normal control group. In hyperechogenic fetal kidneys (ARPKD, ADPKD and transient sonographic abnormalities), these markers were not different from controls. However, whereas normal values cannot exclude renal failure, abnormal values predict post-natal renal failure. CONCLUSIONS: In bilateral renal hypoplasia and dysplasia, fetal serum ss2-microglobulin and cystatin C are good markers for post-natal renal function. However, in bilateral renal hyperechogenic enlargement, abnormal values are associated with poor post-natal renal function, but normal values cannot preclude renal failure.     

Oxytocin secretory response to breast stimulation in pregnant women

Infantile polycystic kidney disease in an autosomal recessive disorder which in its severe form is characterized by bilateral renal enlargement and renal failure. The present study was undertaken to assess the diagnostic accuracy of antenatal sonography in a population at risk. Nineteen patients with fetuses at risk for infantile polycystic kidney disease were referred for ultrasound examination to the Perinatal Unit at Yale-New Haven Hospital. Ten infants had infantile polycystic kidney disease (53%). A positive antenatal sonographic diagnosis was made by the presence of oligohydramnios, an absent urinary bladder, bilateral renal enlargement as measured by the kidney circumference-to-abdominal circumference ratio, and the typical hyperechogenic appearance of the kidneys in the disease. A correct antenatal diagnosis was made in nine of the 10 affected infants. There were no false positive diagnoses. A false negative diagnosis occurred in an infant with a less severe form of the disease. Ultrasound is a valuable tool in the antenatal diagnosis of infantile polycystic kidney disease.     

Prenatal diagnosis of autosomal recessive polycystic kidney disease by ultrasonography and magnetic resonance imaging.

Autosomal recessive polycystic kidney disease is a relatively rare congenital disease affecting the kidneys and liver. We noticed the kidney abnormality at 22 weeks gestation and observed the patient till the delivery at 36 weeks of gestation. The ultrasonographic features consisted of bilaterally enlarged hyperechogenic kidneys, oligohydramnios, lack of distention and difficulty in identifying the fetal urinary bladder. The serial sonographic features of the kidneys changed as pregnancy progressed. The kidney cysts gradually changed in size, shape and renal texture, but the umbilical velocimetry and the kidney circumference/abdominal circumference ratio did not change. Magnetic resonance imaging also showed similar characteristic features as observed by ultrasonography.     

Third trimester ultrasonic presentation of infantile polycystic kidney disease

Infantile polycystic kidney disease (Potter's Type 1) is an autosomal recessive disorder that affects the kidneys and liver. Use of ultrasound to make the diagnosis prenatally is well documented and, in fact, it is advocated as a screening device for second-trimester identification of potentially affected fetuses. The sonographic appearance is characterized by enlarged hyperechoic kidneys, enlarging fetal abdominal circumference, and oligohydramnios. It is suggested that a ratio of the kidney circumference to the abdominal circumference (KC/AC) be used as method of quantifying renal size and as a potential indicator of early kidney enlargement associated with infantile polycystic kidney disease (IPKD). We report a case of serial ultrasound examination of a pregnancy at risk for IPKD where the in utero diagnosis was not established until the third trimester.     

Sonographic findings of fetuses with an empty renal fossa and normal amniotic fluid volume

OBJECTIVE: To review the antenatal sonographic findings and postnatal follow-up of fetuses with empty renal fossa (ERF) and normal amniotic fluid volume. METHODS: Sonographic examinations of 13,705 fetuses were retrospectively analyzed and all fetuses with at least one ERF and normal antenatal amniotic fluid volume were included in this study. RESULTS: Forty cases with antenatal ERF were diagnosed. Prenatal diagnosis consisted of pelvic kidney (n = 24), unilateral renal agenesis (n = 13), horseshoe kidney (n = 2) and crossed fused renal ectopia (n = 1). The prevalence of ERF in the low-risk population approximated 3.2 per thousand. There was no serious renal complication during a mean follow-up period of 30 months except one case of crossed fused renal ectopia requiring hemodialysis. CONCLUSION: The underlying cause of ERF in the majority of cases with normal amniotic fluid volume is renal ectopia. Prenatal ultrasonography seems to be highly reliable in diagnosing these anomalies. Prognosis is favorable in the absence of additional extraurinary malformations.     

Autosomal recessive polycystic kidney disease. Problems of prenatal diagnosis

Autosomal recessive polycystic kidney disease (ARPKD) is characterized by different proportions of cystic dilated collecting ducts invariably associated with congenital hepatic fibrosis. Because of the nearly regular arrangement of nephrons and collecting ducts, disturbances have been postulated to act rather late on embryological grounds. Prenatal diagnoses seem to confirm this observation, as can be demonstrated in our cases and those reported in the literature. Increased echogenicity and renal enlargement are the main ultrasonographic signs of ARPKD; oligohydramnios is characteristic but not always present. Repeated sonographic measurements of the kidney length seem to be the most useful parameter. As differential diagnoses, autosomal dominant polycystic kidney disease as well as Meckel syndrome have to be taken into consideration. The prognosis of cases with oligohydramnios is usually poor. In genetic counselling, the possibility of prenatal diagnosis in the second trimester of pregnancy should be given with caution.     

Unexpected ultrasonographic prenatal diagnosis of autosomal dominant polycystic kidney disease

The prenatal diagnosis of autosomal dominant polycystic kidney disease (ADPKD) is now being reported with increasing frequency. We report three cases and review 12 cases of ADPKD diagnosed in the fetus by ultrasonographic findings. Increased echogenicity and renal enlargement are the main ultrasonographic signs of ADPKD. Renal cysts are uncommon. Diagnosis is easy in a family with a positive ADPKD history. Conversely, there may be no apparent family history, as in our three cases and three cases from the literature. We consider the problems of unexpected diagnosis, family investigation, and the prognosis of ADPKD in children with prenatally diagnosable forms.     

Clues and pitfalls in the early prenatal diagnosis of 'late onset' infantile polycystic kidney.

Infantile polycystic kidney disease (IPKD) is an autosomal recessive inherited disorder, IPKD has been previously diagnosed by us as early as the 14th week of gestation. 'Late onset' (third trimester) IPKD has been previously described by several authors. We present here a case of intrauterine detection of 'late onset' IPKD, suggesting that elongated hyperechogenic kidneys (with normal transverse and anteroposterior diameters) should be considered as an early sign of 'late onset' presenting IPKD.     

Antenatal diagnosis of renal anomalies with ultrasound. IV. Bilateral multicystic kidney disease

Bilateral multicystic kidney disease is a congenital disorder that is fatal in the newborn period. A series of nine cases of bilateral multicystic kidney disease diagnosed prenatally by ultrasound is presented. Ultrasound criteria necessary for the diagnosis are bilateral multicystic kidneys, loss of renal architecture, nonvisualization of the fetal bladder, and absence of amniotic fluid. Seven of the nine cases had autopsy confirmation of the diagnosis. Three cases had other associated congenital anomalies. Precise prenatal diagnosis may allow patients the option of elective abortion or may prevent unnecessary obstetric intervention. We propose that a reliable diagnosis can be made with prenatal ultrasound.     

Fetal kidney volume and urine production in cases of fetal growth retardation

The amount of amniotic fluid has a close correlation to the function of the fetal renal system. In many cases of fetal growth retardation oligohydramnios is obvious. The aim of this study is the investigation of the hourly fetal urine production rate (HFUPR) and the growth of fetal kidneys during pregnancy in cases of fetal growth retardation and to evaluate the renal participation in the origin of oligohydramnios in cases of growth retardation. In 52 healthy pregnancies and 27 cases with known fetal growth retardation, the volume of the fetal kidneys was measured sonographically and the hourly rate of fetal urine production was determined. Two third of the patients with fetal growth retardation had obvious oligohydramnios. In cases of fetal growth retardation the volume of the fetal kidneys was significantly smaller when compared to the control group, and the volume of fetal urine production was significantly lower. The reduced perfusion of the fetal kidneys in those cases with fetal growth retardation may be the reason for the reduction of the HFUPR. Due to the fact that HFUPR is a dynamical parameter and in close relationship to the perfusion of the fetal kidneys, the identification and measurement of this parameter may help to detect subacute and imminent fetal distress in cases of sonographically proven fetal growth retardation.     

Prenatal diagnosis of the hemodynamics of fetal renal disease by color Doppler ultrasound

OBJECTIVE: Hemodynamic analysis of the fetal renal artery elucidated the function of the renal glomerulus and renal tubule in normal growth fetus and was weighed against fetal renal disease. DESIGN: The subjects were fetuses from pregnant women who gave informed consent. There were 6 cases of polycystic kidney, 4 cases of hydronephrosis and 33 cases of fetuses presenting with normal growth. A longitudinal study was performed for normal growth fetuses. Using maximum systolic velocity (V(max)), pulsatility index (PI) and resistance index (RI), the blood flow was measured initially at 20-24 weeks of pregnancy and every 4 weeks thereafter. The measurement was performed 5 times in total. Also, for fetal renal disease, the measurement was performed using the same indexes. RESULTS: In 2 cases of polycystic kidney, which led to death due to postpartum afunctional kidney, V(max) indicated the lower level of less than mean -1.5 SD. In 1 case of single hydronephrosis, the single afunctional kidney was observed postpartum due to blood flow disruption. In 7 cases of normal renal function after birth, it indicated the lower level in some gestational ages but was generally in the normal range. CONCLUSIONS: Using indexes to evaluate the glomerulus and renal tubule of fetal renal disease, mean -1.5 SD of V(max) can be considered to be the lower limit in the normal range and expected to be an important factor for the final outcome.     

Hemodynamics of the renal artery and descending aorta in fetuses with renal disease using color Doppler ultrasound--longitudinal comparison to normal fetuses

OBJECTIVE: To examine the hemodynamic values of the renal artery (RA) and descending aorta (DA) in normal fetuses, and to compare these values to those of fetuses with renal disease, thus evaluating the usefulness of hemodynamic analysis for the diagnosis of fetal renal disease. MATERIALS AND METHODS: We examined 46 normal fetuses and 15 fetuses with renal disease (six cases of polycystic kidney (PCK) and nine cases of hydronephrosis). We measured the maximum systolic velocity (Vmax ) of the RA and DA using color Doppler. Measurements were made five times, from the 20th to the 40th week, in both the control and the renal disease group. RESULTS: In the fetuses with PCK (Potter's syndrome) that died postpartum from non-functional kidneys, the Vmax of the RA and DA in the 35th week were 13 cm/s and 25.4 cm/s, respectively. In the fetus with PCK (Trisomy 9) that died due to non-functional kidneys in the 34th week, the values were 13.3 cm/s and 29.6 cm/s, respectively. These values were well below those of the normal group: more than 1.5 SD below the mean. In two fetuses from the nine with hydronephrosis that had a unilateral non-functional kidney, the RA did not clearly show identifiable blood flow. CONCLUSIONS: The V max of the RA and DA in fetuses with renal disease correlates with fetal kidney function, particularly the RA Vmax.Vmax of 1.5 SD below the mean should be the lower normal limit.     

Fetal blood volume, urine flow, swallowing, and amniotic fluid volume responses to long-term intravascular infusions of saline

The purpose of this study was to determine the effects of a long-term infusion into the fetal circulation on fetal and amniotic fluid dynamics. In 10 chronically catheterized fetal sheep averaging 130 +/- 1 (SE) days' gestation, a balanced, isotonic electrolyte solution (Isolyte S) was infused continuously for 5 days into a fetal vein at a rate of 0, 1, 2, 4, and 0 L/day, respectively. During the infusion, fetal blood volume increased by a maximum of 6.4 +/- 2.0% (p less than 0.001), and the daily swallowing of amniotic fluid doubled (p less than 0.001). Fetal urine flow increased (p less than 0.0001) above preinfusion rates by a volume equal to the infusion rate plus the increase in swallowing, whereas renal excretion of sodium and chloride increased by the amount infused. The increase in the plasma concentration of atrial natriuretic factor (p less than 0.0001) and the decrease in arginine vasopressin (p less than 0.05) were not linearly related to urine flow changes. Amniotic fluid volume increased (p less than 0.0001) by 20% of the infused volume. All values returned to normal on day 5 except amniotic fluid volume, which remained elevated. Estimated allantoic fluid volume at the end of day 5 was 800 ml above normal. Thus it appears that on a long-term basis, the ovine fetus eliminates infused water and electrolytes through its kidneys rather than across the placenta. Although all of the infused volume left the fetus through its kidneys, only 30% of the infused volume remained in the amniotic and allantoic fluid compartments, suggesting transfer to the mother by unknown mechanisms.     

The accuracy of the assessment of normal fetal intestinal echogenicity--electro-optical densitometry versus the ultrasonographer's eye.

Ten plates of normal fetal ultrasonography (at 16-20 weeks' gestation) showing fluid, liver, lung, bone and intestine were submitted to electro-optical transmission surface densitometry. A distinct echogenic gradient has been found and used as an 'internal standard' to evaluate intestinal echogenicity. Intestine had significantly different echogenic properties from bone, liver and fluid but similar to that of lung. Using this echogenicity scale for fetal bowel, observers were correct in 46%, overscored in 32.6% and underscored in 21.4%. These poor results may be due to the significant inconsistency in the interpretation of each plate compared to other plates (about 65%). Although the densitometry-derived grading scale seems valid at these gestational ages, interobserver variation is too large and precludes a simple ultrasonic diagnosis of the hyperechogenic fetal intestine. Densitometric evaluation may be indicated in suspected cases when fetal bowel seems to have increased echogenicity.     

Isolated fetal hyperechogenic bowel associated with intra-uterine parvovirus B19 infection

We report a case of fetal hyperechogenic bowel diagnosed at midgestation that was associated with fetal parvovirus B19 infection. Isolated hyperechogenic bowel was detected at 25 weeks. Cystic fibrosis, chromosomal abnormalities and cytomegalovirus infection were excluded, whereas polymerase chain reaction DNA for parvovirus B 19 was found positive on amniotic fluid. The hyperechogenic bowel decreased with complete resolution by 32 weeks of gestation. No other signs of fetal B19 infection were detected prenatally and the baby had normal postnatal outcome. This case provides additional arguments in favor of a possible intestinal tropism of parvovirus B19 during fetal life. Fetal B19 infection should be systematically incorporated in the prenatal evaluation of isolated fetal hyperechogenic bowel.     

Perinatal differential diagnosis of cystic kidney disease and urinary tract obstruction: anatomic pathologic, ultrasonographic and genetic findings

According to the classification of Osathanondh and Potter of cystic kidney diseases an antenatal differential diagnosis is presented, which is based on the anatomic pathologic, ultrasonographic and genetic findings. Since the ultrasound evaluation influences the obstetric and neonatal management, each second and third trimester sonography should consider the most common malformations in pediatric autopsies. The autosomal recessive polycystic kidney disease (ARPK), autosomal dominant polycystic kidney disease (ADPK), multicystic renal dysplasia, obstructive multicystic kidneys and cystic renal malformations found in other syndromes with genetic linkage are discussed in this review.     

Alpha-Fetoprotein and renal dysfunction of the fetus.

Alpha-fetoprotein (AFP) levels were measured in 25 pregnancies with renal dysfunction of the fetus. Oligohydramnios was found in 14 of 16 patients diagnosed by 20 weeks of gestation and in all of those diagnosed later. AFP levels in maternal serum were normal in 17 (68%), elevated in five (20%), and low in three patients (12%). AFP serum levels up to 24 weeks of gestation were significantly higher than after 24 weeks. AFP levels in amniotic fluid obtained from amniocentesis in six patients were normal or slightly elevated. We suggest that the concentration of AFP in amniotic fluid and maternal serum does not only depend on the physiologic proteinuria of the immature fetal kidneys but also on the permeability of the not yet keratinized fetal skin and the diluting volume of the amniotic fluid.