Transvaginal sonography (TVS) of the fetal urinary tract

Examination of the fetal urinary tract is an integral part of routine sonographic examination in the second trimester of pregnancy. Malformations of the urinary tract are being detected at an ever-increasing rate, mostly because they are associated with two easily visualized sonographic markers: the cystic accumulation of fluid and a change of the amniotic fluid volume. Detailed evaluation of the fetal urinary tract and identification of anomalies were considered to be difficult before the 18th week from the last menstrual period (LMP) before the use of transvaginal sonography (TVS). Transvaginal sonography (TVS), owing to its proximity to the maternal pelvic organs at early gestation, enables earlier determination of both normal and abnormal findings in the fetal urinary system such as: renal agenesis, polycystic and multicystic kidneys, hydronephrosis, and bladder extrophy. The TVS enables earlier and more accurate diagnosis and identification of fetal urinary tract anomalies as compared with abdominal ultrasound.     

Fetal syphilis: correlation of sonographic findings and rabbit infectivity testing of amniotic fluid

Fetal syphilis is the presumed diagnosis when the sonographic findings of fetal hydrops are found in the presence of maternal syphilis. In the absence of fetal hydrops, the diagnosis of fetal infection is difficult. We hypothesized that intra-amniotic infection would be accompanied by anatomic placental and fetal abnormalities that could be detected by ultrasonography. Rabbit infectivity testing (RIT), intratesticular inoculation of rabbits with amniotic fluid, can be used to confirm intra-amniotic infection with Treponema pallidum. Twenty-one gravidas with untreated early (primary, secondary, and early latent) syphilis underwent sonography and amniocentesis for RIT at 24 weeks of gestation or later. Antenatal sonographic findings were compared to their amniotic fluid RIT results. Hepatomegaly was significantly (P < 0.01) associated with amniotic fluid infection detected by RIT. Antenatal detection of hepatomegaly, which is probably the initial sonographic manifestation of hydrops fetalis, may ultimately identify the fetus affected with congenital syphilis.     

Oligohydramnios associated with bilateral multicystic dysplastic kidneys: prenatal diagnosis at 15 weeks' gestation

Lethal fetal renal malformations are invariably associated with oligohydramnios in late antennatal ultrasound examinations. Controversy exists concerning the contribution of fetal urine production to amniotic fluid volume prior to 20 weeks' gestation. We report a pregnancy complicated by maternal gold usage and fetal bilateral multicystic dysplastic kidney disease in which oligohydramnios was detected at 12 weeks' gestation. To our knowledge, no previous cases of lethal fetal renal anomalies have been made in the first trimester. The early diagnosis of fetal renal anomalies, fetal renal contribution to amniotic fluid production, and possible teratogenicity of gold therapy is discussed.     

产前超声对于胎儿子宫的评估

目的利用超声测量不同孕周胎儿子宫的前后径及横径,建立胎儿期子宫前后径及横径与孕周的关系。方法收集285例19~37孕周的女性胎儿,横切面超声扫查,于胎儿低位盆腔内、膀胱与直肠之间测量其子宫前后径及横径,三次测量取平均值,利用SPSS 22.0软件进行统计分析。结果胎儿子宫前后径及横径均随孕周增加而增长,呈线性相关(R^2=0.919,P<0.001;R^2=0.920,P<0.001),经线性回归分析建立胎儿子宫前后径及横径与孕周的线性回归方程:子宫前后径(mm)=0.45×孕周-4.9,子宫横径(mm)=0.51×孕周-3.8;同时提供了各孕周胎儿子宫前后径及横径的均数、标准差及95%可信区间。结论女性胎儿子宫在孕19周后产前超声扫查可显示,其前后径及横径与孕周呈线性正相关。     

The effects of maternal and fetal parameters on the quality of nuchal translucency measurement.

OBJECTIVE: To evaluate the influence of maternal and fetal parameters on the quality of fetal nuchal translucency measurement. DESIGN: This was a prospective study in 227 consecutive pregnant women undergoing nuchal translucency screening by transabdominal sonography. The same well-qualified sonographer performed all the scans and in each case the best-quality image was selected and scored according to an image scoring system (total maximum score, 9). The quality of the image was examined in relation to maternal age, weight, abdominal wall thickness, amniotic sac diameter, posterior uterine wall depth (distance between abdominal wall surface and posterior uterine wall surface), placental location, fetal crown-rump length and nuchal translucency thickness. Correlation coefficients were calculated and stepwise linear regression was used to adjust for confounders and to define the predictors for image score. RESULTS: The only two parameters that provided a significant independent contribution to the prediction of the image score were posterior uterine wall depth and fetal crown-rump length. Intravariable analysis of these two parameters demonstrated that the cut-off associated with a significant change in the image quality was 80 mm for posterior uterine wall depth (score difference, 1.06; P < 0.001) and 70 mm for crown-rump length (score difference, 0.77; P = 0.001). In the group of women with two values above these cut-off points, an average score decrease of 1.90 (P < 0.001) was observed. CONCLUSIONS: The quality of fetal nuchal translucency measurement is poorer when the fetal crown-rump length is > 70 mm and the posterior uterine wall depth is > 80 mm.     

Ultrasonically determined menstrual age as an indicator of fetal lung maturity

The usefulness of ultrasonically determined menstrual age as a predictor of fetal lung maturity has been evaluated in patients without fetal or maternal disease undergoing repeat cesarean section. The menstrual age of each fetus was determined at 18–32 wk using biparietal diameter (BPD) measurements and previously established BPD growth curves. Lung maturity prior to delivery was assessed by measuring the lecithin/sphingomyelin (L/S) in amniotic fluid. The menstrual age at the time of the amniocentesis was derived by extrapolation from the results of the first scan. When the Sabbagha Composite BPD growth curve was used for menstrual age determinations, the L/S was <2.0 in all cases before 34 wk, both <2.0 and ≥2.0 between 34 and 38 wk, and ≥2.0 in all but one case after 38 wk. This one case represents 1.2% of fetuses studied. These results suggest that in the absence of fetal and maternal disease, a menstrual age of 38 wk or older, based on an early BPD measurement and use of the Sabbagha Composite BPD growth curve, is indicative of lung maturity in most cases.     

Severity of polyhydramnios does not affect the prevalence of large-for-gestational-age newborn infants.

The purpose of this study was to evaluate the relationship between the severity of polyhydramnios with or without maternal diabetes and the prevalence of large-for-gestational-age newborn infants. A case control design was used. The study group consisted of 275 singleton pregnancies with an amniotic fluid index > or = 25.0 cm. An equal number of controls was matched for maternal age, gravidity, parity, and gestational age. Polyhydramnios was categorized into three groups by severity: mild (amniotic fluid index 25 to 30 cm.); moderate (amniotic fluid index, 30.1 to 35.0 cm); and severe (amniotic fluid index > or = 35.1 cm). Among our study group, 72.7%, 19.7%, and 7.6% of cases had mild, moderate, and severe polyhydramnios, respectively. Patients with polyhydramnios had a significantly higher prevalence of large-for-gestational-age neonates (27%) than did controls (10%) (P < 0.001). No correlation was seen between the severity of polyhydramnios and neonatal delivery weight. The prevalence of gestational and class > or = B diabetes mellitus was significantly higher among patients with polyhydramnios (17.7%) than among controls (7%) (P < 0.003). Once polyhydramnios was diagnosed sonographically, however, maternal diabetic status did not affect the prevalence of large-for-gestational-age newborn infants. We conclude that the prevalence of large-for-gestational-age neonates is 2.7 times greater when polyhydramnios is present than when the amniotic fluid volume is normal. Neither the severity of polyhydramnios nor the presence of maternal diabetes mellitus strengthens the relationship between polyhydramnios and large-for-gestational-age newborn infants.     

Exhaled nitric oxide concentration and amniotic fluid nitrite concentration during pregnancy

Abstract. We have assessed fetal and maternal nitric oxide (NO) production in pregnancy. Exhaled NO and amniotic fluid nitrite concentrations were measured by chemiluminescence between 10 and 42 weeks of pregnancy. Exhaled NO concentrations did not alter significantly during gestation. In contrast, there was a significant change in mean amniotic fluid nitrite concentration in late pregnancy ( P < 0.001). The finding of decreased amniotic nitrite concentrations after 37 weeks of gestation support the hypothesis that reduced NO production may contribute to increased uterine activity in late pregnancy.     

Urinary excretion of meperidine by the fetal lamb.

The renal excretion of meperidine by the fetus was determined in five chronic, unanesthesized fetal lamb preparations. Chronic indwelling catheters were implanted in the maternal aorta and vena cava, the fetal aorta, amniotic sac and allantoic sac. Via laparotomy, two catheters were implanted in the fetal bladder; the urachus and urethra were ligated. After intravenous administration of 2.5 mg/kg to the mother, meperidine rapidly appears in fetal urine. Approximately 0.02 to 0.05% of the maternal dose was excreted into fetal urine as unchanged meperidine in 300 min. The elimination half-life of meperidine in the fetus is 32.6 +/- 3.7 min when calculated from the urinary excretion rates, and 28.6 +/- 3.9 min when estimated from the plasma decay curve. The renal clearance of meperidine by the fetus ranged from 2.8 to 16.7 ml/min. Although the urachus and urethra were ligated, meperidine is found in samples of amniotic and allantoic fluid, indicating that the drug can diffuse across the placental membranes from the mother into these fluids. We have demonstrated that renal elimination of meperidine is a route of drug elimination by the fetus. These data support a pharmacokinetic model that describes the disposition of meperidine in the maternal-fetal unit by use of a two-compartment open model with elimination from both maternal and fetal compartments.     

Enlarged fetal bladder: Differential diagnosis and outcomes

The sonographic finding of an enlarged fetal bladder may simply be a transitory normal variant, but it may also be secondary to reflux or to obstructive, neurogenic, or myopathic causes. In this report, we describe the cases of 3 fetuses with an enlarged bladder, each of which had a different cause. The first fetus had posterior urethral valve obstruction, the second, a ruptured neurogenic bladder, and the third, megacystic-microcolon-intestinal hypoperistalsis syndrome. When sonographic examination reveals an enlarged fetal bladder, the ureter, kidneys, genitalia, and spine should be evaluated carefully. Although sonography is good at identifying urinary tract abnormalities, it often cannot provide the specific diagnosis or cause. We recommend frequent sonographic monitoring to evaluate such fetuses for persistence of or changes in bladder enlargement and for changes in the volume of amniotic fluid because these signs may be indicators of abnormalities of renal function and risk factors for a poor prognosis. Analysis of fetal electrolyte levels can also aid in determining the prognosis and whether the condition is amenable to therapeutic intervention.     

Sonographic findings in a fetus with megacystis-microcolon–intestinal hypoperistalsis syndrome

We describe the perinatal findings in a female fetus with megacystis-microcolon–intestinal hypoperistalsis syndrome (MMIHS). Prenatal sonography performed during 18–21 weeks' gestation showed a normal amount of amniotic fluid, but the fetus was seen to have a persistently distended stomach, a hugely distended bladder, and bilateral dilated renal calyces. Genetic analysis of amniotic fluid revealed a 46,XX karyotype. The pregnancy was terminated at 22 weeks' gestation. At necropsy, the fetus was found to have prune-belly syndrome, gastric dilatation, pronounced megacystis, bilateral hydronephrosis and megaureters, short bowel, microileum, microcolon, and malrotation of the intestines. This fetus showed the typical clinical and sonographic features of MMIHS, as well as the rare antenatal finding of persistent gastric distention. © 1998 John Wiley & Sons, Inc. J Clin Ultrasound 26:217–220, 1998.     

Cervical length as a prognostic factor for preterm delivery in twin-to-twin transfusion syndrome treated by fetoscopic laser coagulation of chorionic plate anastomoses.

OBJECTIVE: To evaluate the risk of spontaneous preterm delivery in relation to cervical length in severe cases of twin-to-twin transfusion syndrome (TTTS) diagnosed before 26 weeks of gestation and treated by laser coagulation of the intertwin placental anastomoses. METHODS: This was an observational study of cases of severe TTTS diagnosed before 26 weeks of gestation and treated by fetoscopic laser coagulation between January 2002 and December 2003 in three centers. Laser was the first-line treatment in all cases. Elective preterm deliveries before 34 weeks' for maternal or fetal indications, including intrauterine death of both fetuses, were excluded. Transvaginal sonographic measurement of cervical length prior to laser treatment and other risk factors of preterm delivery were evaluated by univariate and logistic regression analysis. RESULTS: Among the 137 women included, the mean cervical length was 32 and 38 mm in women delivering before and at or after 34 weeks, respectively (P < 0.001). For a cervical length of < 30 mm, the risk of delivery before 34 weeks was 74%. Severity of the disease, deepest vertical pool of amniotic fluid and amniotic fluid volume drained after the procedure were not associated with preterm delivery. Logistic regression analysis identified three independent factors to predict preterm delivery: short cervical length (increased risk), parity (increased risk) and intrauterine death of one twin (decreased risk). CONCLUSION: In TTTS treated by laser, without indications for elective preterm birth, cervical length before treatment is significantly associated with gestational age at delivery, and this is independent of parity, intrauterine death of one fetus and other risk factors.     

Caudal regression versus sirenomelia: sonographic clues

Seven cases with the pathologic/autopsy diagnosis of caudal regression or sirenomelia in which antenatal sonography had been performed were reviewed. The three patients with caudal regression had similar findings on antenatal sonogram, including normal or increased amniotic fluid, mild dilation or normal urinary systems, nonfused extremities, and sacral agenesis. In the four patients with sirenomelia, common sonographic findings included marked oligohydramnios, suspected renal agenesis, and sacral agenesis. A history of maternal diabetes was elicited in all patients with caudal regression and in none of the patients with sirenomelia. Findings confirm recent articles in pediatric pathology suggesting that caudal regression is a separate entity, distinct from sirenomelia.     

彩色多普勒超声诊断肾盂癌

目的　分析肾盂癌的超声诊断特点以提高其诊断准确率。方法　应用彩色多普勒超声诊断肾盂癌患者 2 2例 ,分析其声像图特征。结果　大部分肾盂癌患者有肾脏肿大 ,肾盂积水 ,肾盂包块典型声像图表现。结论　在肾盂积水条件下 ,超声诊断小肾盂肿瘤 (d <2cm)更准确。     

Non protein bound iron concentrations in amniotic fluid

OBJECTIVES: To investigate whether amniotic fluid concentrations of non protein bound iron (NPBI) vary with growth in healthy fetuses and also offer a reference curve in the second trimester of pregnancy. DESIGN AND METHODS: Amniotic fluid concentrations of NPBI were measured by HPLC in 118 women with physiological singleton pregnancies, who underwent amniocentesis for fetal karyotype between weeks 15 and 18 of gestation. RESULTS: NPBI increased progressively from weeks 14--15 to weeks 15--16, peaking at 17--18 weeks of gestation. NPBI values regressed positively with gestational age (GA). Multiple linear regression analysis between NPBI, as dependent variable, and various fetal parameters, as independent variables, showed a statistically significant regression coefficient with GA, bi-parietal diameter and transverse cerebellar diameter. CONCLUSIONS: The present data constitutes the first quantification of NPBI concentrations in amniotic fluid under physiological conditions. Correlations with GA and ultrasound fetal biometry suggest that NPBI may play a role in fetal growth.     

Correlation between fetal gastric size and amniotic fluid volume

PURPOSE: Since abnormal conditions of the fetal digestive tract may alter both amniotic fluid volume and fetal gastric volume, we sought to determine whether amniotic fluid volume is correlated with fetal gastric volume in normal pregnancy. METHODS: A total of 280 fetal gastric size measurements were made prospectively from routine sonographic examinations of women with normal singleton pregnancies between 16 and 42 weeks of gestation. The fetal stomach was defined as the largest area including the pyloric site on transverse or oblique real-time sonographic scans. Gastric volume was calculated according to the formula for a prolate ellipsoid. The amniotic fluid index (AFI) was used for the evaluation of amniotic fluid volume. RESULTS: Both fetal gastric volume and AFI were significantly correlated with gestational age (R2= 0.422 and R2= 0.128, respectively). Only a weak correlation was found between gastric volume and AFI (R2= 0.036, p <0.001). On multivariate linear regression analysis adjusting for gestational age and fetal biometric measurements, gastric volume was not an independent and significant predictor of AFI. CONCLUSIONS: Although sonographically determined fetal gastric volume measurements appear to be useful in the assessment of fetal digestive tract anomalies, fetal gastric volume has no clinically significant effect on the amniotic fluid volume in normal pregnancy.     

Prostate-specific antigen in amniotic fluid of normal and abnormal pregnancies

Objective: To examine if prostate-specific antigen (PSA) is present in amniotic fluid or maternal serum during pregnancy and if its presence is associated with fetal abnormalities.

Methods: Samples tested included amniotic fluids from 853 pregnant women for whom amniocentesis was performed; 312 nonpregnant women who donated blood; 259 pregnant women who donated blood at various gestational ages. Amniotic fluid or serum PSA was measured with an ultrasensitive time-resolved immunofluorometric procedure. 372 pregnancies were studied for the presence of genotypic or phenotypic fetal abnormalities.

Results: PSA was present in most amniotic fluids; the median PSA concentration increased from gestational week 11 to 22 and stabilized thereafter until delivery. The most prominent PSA concentration change occurred during gestational weeks 13–14. Pregnant women had significantly higher serum PSA concentrations than nonpregnant women; the pattern of serum fSA concentration change during pregnancy was similar to that of amniotic fluid; however, serum PSA concentrations were lower by a factor of 20–40. No association existed between amniotic fluid F'SA and maternal age, gender of fetus, or length of abstinence of mother from sexual intercourse. After gestational week 15, fetuses with trisomy 21 or 18, anencephaly, or renal disorders were associated with low amniotic fluid PSA levels.

Conclusion: Our data suggest that PSA may play a role in fetal development, especially at gestational ages between 13–20 weeks. The diagnostic usefulness of PSA in identifying fetal abnormalities remains to be determined.     

Maternal Obesity Limits the Ultrasound Evaluation of Fetal Anatomy

Objective. The purpose of this study was to evaluate the effect of maternal habitus on adequate visualization of fetal anatomy during a standard second‐trimester ultrasound examination. Methods. This was a retrospective cohort study of singleton pregnancies at 18 to 24 weeks that underwent sonography over a 5‐year period. Pregnancies complicated by an indication for targeted sonography were excluded. Standard ultrasound examinations were performed according to American Institute of Ultrasound in Medicine criteria. Ten anatomic components were evaluated for adequacy of visualization: atria of the cerebral ventricles, posterior fossa, midline face, 4‐chamber view of the heart, spine, ventral wall, umbilical cord vessels, stomach, kidneys, and bladder. The body mass index (BMI) was based on the patient's weight at the first prenatal visit. Results. Of 10,112 women who underwent a standard ultrasound examination, 2% were underweight; 38% were of normal weight; 34% were overweight; and 26% were obese. Visualization of fetal anatomy decreased significantly with increasing maternal BMI for the complete survey as well as for each individual component with the exception of the fetal bladder (all P < .001). Among those with a normal or underweight BMI, an overweight BMI, and class 1, 2, and 3 obesity, all 10 anatomic components were adequately visualized at the initial examination in 72%, 68%, 57%, 41%, and 30% of cases, respectively (P < .001). Conclusions. Increasing maternal BMI limits visualization of fetal anatomy during a standard ultrasound examination at 18 to 24 weeks. In obese women, the fetal anatomy survey could be completed during the initial examination in only 50% of cases. Counseling may need to be modified to reflect the limitations of sonography in obese women.     

Early fetal echocardiography: heart biometry and visualization of cardiac structures between 10 and 15 weeks' gestation.

OBJECTIVE: The purpose of this prospective cross-sectional study was to compile normative data about biometry of the fetal heart and great vessels between 10 and 15 weeks in 123 normal singleton pregnancies. Additionally, we investigated the different methods and the optimal examination time of early fetal echocardiography. METHODS: The interrogated parameters included total heart diameter; heart area and circumference; right and left ventricular diameter; diameter, circumference, and area of the thorax; and diameter of the aorta and pulmonary trunk. Visualization of the 4-chamber view, 3-vessel view, origin and crossover of the great arteries, aortic arch, ductus arteriosus, superior and inferior venae cavae, and pulmonary veins was analyzed, and the success rates by transvaginal sonography (TVS) and transabdominal sonography (TAS) were calculated. RESULTS: Complete evaluation of the fetal heart was impossible at 10 weeks; the total success rate increased from 45% at 11 weeks to 90% between 12 and 14 weeks and 100% at 15 weeks. Between 10 and 13 weeks, TVS was superior to TAS. At 14 weeks, both methods were similar to each other, and at 15 weeks, TAS allowed adequate visualization of all structures. Linear regression analysis showed a significant correlation between the interrogated parameters and gestational age, crown-rump length, and biparietal diameter (P < .05). The ratio of right and left ventricular diameters and the ratio of pulmonary trunk and aortic diameters were constant. CONCLUSIONS: Early fetal heart evaluation by TVS or TAS or both is reasonable and feasible. Our normative data could be helpful for understanding the normal development of the fetal heart and great arteries and for detection of cardiac defects in early pregnancy.     

经会阴超声观察不同分娩方式对盆底结构的影响

目的经会阴超声观察不同分娩方式女性产后盆底结构,为研究盆底功能障碍性疾病提供影像学依据。方法初产妇69例,分为经阴道分娩组39例和剖宫产组30例,产后6~8周,经会阴超声分别在静息状态、瓦氏动作时测量盆膈裂孔面积、周长、前后径、左右径及膀胱颈移动度(BND)。结果经阴道分娩组静息状态下,盆膈裂孔面积、周长、前后径及左右径均大于剖宫产组(均P0.05);经阴道分娩组BND大于剖宫产组(P0.05);同组瓦氏动作时各参数大于静息状态(P0.01);两组瓦氏动作时各参数差异无统计学意义。结论经会阴超声观察产后盆底结构,为女性盆底功能障碍性疾病的早期防治提供辅助诊断依据。