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Significance of fetal renal pelvis dilatation detected by sonography
260
SPO Abstracts
January 1995 Am J Obstet Gynecol
19 FIR~]L' 21LII4E~LT,R DOWN 8Tl~RQIm BCIUWMING: FRill • .A
,,,--t.",
J. , . . , . . n ' ,
,.
Buchanan , Laboratories, Znc, Huntington Station, NY, 2George W a s h i n g t o n University Medical Center, Washington, DO, ~GeneCare Medical Genetics Center, Chapel Hill, NC. OIkJ~L~EI~: To determine the feasibility of a first trimester Down Syndrome (DS) screening protocol including free Beta (FB) and pregnancyassociated plasma protein A (PAPP-A}. 8'J~DY Dlmleli: First trimester m a t e r n a l blood samples from 22 DS and 483 control cases were assayed for FB and PAPP-A. False positive and detection rates were determined based on DS risks calculated from the levels of the biochemical markers and maternal age. Since Ii of the 22 Dow~ syndrome cases were from older pregnancies (>=35 years old), rates were recalculated using the USA age distribution of live births to get a more representative estimate of false positives a n d d e t e c t i o n efficiency. I~dBOLTS: The m e d i a n P A P P - A and FB level in DS cases wan 0.385 and 2.09 MoM, respectively. At a 5.0% false positive rate 15 (68.2%) DS canes were detected. Using the age distribution of live births, 63% of cases could be expected to be detected at a 5.0% false positive rate. CONCLUSION: First trimester FB/PAPP-A screening for DS can achieve detection rates an high as those associated with AFP/hCG or AFP/hCG/uE3 screening in the second trimester. Prospective studies are needed to further assess first trimester screening.
20 COMPARISON OF MULTIPLE MARKER SCREENING WITH ELECTIVE AMNIOCENTESIS FOR DETECTION OF ANEUPLOIDY IN WOMEN > 35. K. Wenstrom, R. Desai x, J. Owen, M. DuBard x, L. Boots x. The University of Alabama at Birmingham. OBJECTIVE: To compare the multiple marker screening test (MMST) with elective amniocenteeis for the detection of fetal Down Syndrome (DS)and other aneuploidies in women age 35 and older. STUDY DESIGN: Our data base included test results from a total of 1,609 women age -> 35 with singleton pregnancies. Fourteen cases of DS and 12 other aneuploidies were diagnosed in 1582 women; 27 retrospective DS cases were also included. All women had both the MMST, (Maternal serum alphafetoprotein, human chorionic gonadotrophin, unconjugated estriol, and maternal age) and a genetic amniocentesis. A D S risk >_ 1:190 was considered screen positive. In addition, an algorithm to detect Trisomy 18 was employed. A positive trisomy 18 screen was defined as MSAFP < 0.75 MOM, hCG < 0.55 MOM and estriol < 0.6 MOM. RESULTS: The MMST screen positive rate was 27.8% (447/1609). Thirty-two of the 41 DS cases had positive screens, for a detection rate of 78%. Two of the 3 cases of Trisomy 18 (66%) were identified by a positive Tdsomy 18 screen. However, the MMST detection rate for all aneuptoidies was only 68% (36/53). The 17 missed aneuploidies were trisomy 21 (n = 9), sex chromosome abnormalities (n = 4), trisomy 13 (n = 2), trisomy 22 (n = 1), and trisomy 18 (n = 1). One aneuploidy was detected for every 13 amniocenteses performed after MMST screening. After subtracting the 27 retrospective DS cases, one aneuploidy was detected for every 61 amnios performed for maternal age in the original 1582 women. CONCLUSIONS: The MMST fails to detect approximately 32% of all fetal aneuploidies in women >_ age 35. The aneuploidies missed by the MMST include diagnoses for which survival with handicap might be anticipated. The current practice of offering elective amniocentesis to these women should be continued.
21 NORMAL NUCHAL THICKNESS IN THE MIDTRIMESTER INDICATES REDUCED RISK OF DOWN SYNDROME IN PREGNANCIES WITH ABNORMAL TRIPLE SCREEN. R. Bahado-Sin~h. I. Goldstein X, B. Uerpalrojkit x, J. A. Copel, M. Mahoneyx, A. Banmgarten x. Yale University School of Medicine, New Haven, CT. OBJECTIVE: Biochemical screening for Down syndrome (DS) has a poor positive predictive value. After a normal ultrasound, many patients with abnormal biochemical screen decline amniocentesis. They assume that negative ultrasound findings reduce overall risk. To test this hypothesis, we studied the effect of normal nuchal thickness (NT) on risk among patients with abnormal biochemical screening for DS. STUDY DESIGN: NT was measured prospectively in 465 mid trimester pregnancies (15-21 weeks), undergoing amniocentesis for abnormal ( > 1/270) risk of DS based on triple screen. NT'e_6nun was considered abnormal. The incidence of DS in the normal NT group was compared to the abnormal NT group. Chi-square analysis and Fisher's exact test were employed. RESULTS: The overall prevalence of DS was 6/465. A normal NT had high specificity (99%). With a normal nuchal thickness the risk of DS was 1/152 compared to 1/2.7 with abnormal NT (p=0.0007). With an abnormal nuchal thickness the risk ratio of having DS is 28.05 (95% CI 9.008, 86.6, p=0.0004). CONCLUSION: Nuchal thickness measurement is the single most sensitive biometric parameter for DS screening in a low risk population. Among patients with an abnormal triple screen, normal NT represented a 50 fold reduction in risk compared to cases with increased NT. This information can be used to further refine risk estimates of DS based on biochemical screening.
SIGNIFICANCE OF FETAL RENAL PELVIS DILATATION DETECTED 22 BY SONOGRAPHY. H. How, F. Tsung," K. Berg-Pass, x L. Goldsmith," J. Spinna'to'~ Dept.of Ob/Gyn, Univ.of Louisville, Louisville, KY. OBJECTIVE: To re-evaluate the existing threshold criteria (Corteville) for the diagnosis and follow-up, both prenatally and postnatally, of congenital hydronephrosis (CH) and to determine the degree of fetal renal pelvis dilatation that best predicts ,~ostnatal renal compromise. TUDY DESIGN: Within a 26-month period, using the criteria for CH as defined by Corteville et al, 112 fetuses (98 prospectively and 14 retrospectively identified) with renal pelvis anteroposterior diameters (APD) of > 4 mm prior to 33 weeks gestation and >7mm after 33 weeks gestation were studied. These fetuses were followed by serial prenatal sonography and then postnatally at 48 hours to 2 weeks and > 3 months of life. Intravenous pyelography, renal scintigrap~'y, and voiding cystourethrography were performed when necessary. Statistical analysis was carried out using the Chi-squared test, Fisher's exact test, cross tabs and receiver operating characteristic (ROC) curve. RESULTS: The incidence of CH in our study was 1.4% (98/7304). There was a predominance of affected males 77.7% (n =87) vs. 22.3% females (n=25); RR of 1.55 (CI 1.25- 1.92). Using a ROC curve, we found that a renal pelvis APD of :>9 mm detected at any time during gestation had a better positive predictive value for an abnormal postnatal scan than Corteville's criteria (35% vs. 18%). The sensitivity, specificity, and negative predictive value using renal pelvis APD of :>9 mm for detection of postnatal hydronephrosis was 85%, 66%, and 95% respectively. Using Corteville's criteria 82% (92/112) fetuses identified as abnormal had no significant neonatal genito-urinary tract pathology. None of the fetuses required early delivery as a result of deteriorating nito-urinary tract findings. NCLUSIONS: Our data suggest that most fetuses with sonographically detected renal pelvis APD of < 9 mm at any time during gestation did not have significant postnatal sequelae, and thus, do not require expensive serial antenatal sonographic surveillance. For fetuses with renal pelvis APD of >- 9 ram. a follow-up prenatal ultrasound at mid-third trimester appears to be adequate surveillance. All fetuses meeting Corteville's criteria should have a follow-up postnatal renal ultrasound within 1-3 months of age.
SPO Abstracts
January 1995 Am J Obstet Gynecol
19 FIR~]L' 21LII4E~LT,R DOWN 8Tl~RQIm BCIUWMING: FRill • .A
,,,--t.",
J. , . . , . . n ' ,
,.
Buchanan , Laboratories, Znc, Huntington Station, NY, 2George W a s h i n g t o n University Medical Center, Washington, DO, ~GeneCare Medical Genetics Center, Chapel Hill, NC. OIkJ~L~EI~: To determine the feasibility of a first trimester Down Syndrome (DS) screening protocol including free Beta (FB) and pregnancyassociated plasma protein A (PAPP-A}. 8'J~DY Dlmleli: First trimester m a t e r n a l blood samples from 22 DS and 483 control cases were assayed for FB and PAPP-A. False positive and detection rates were determined based on DS risks calculated from the levels of the biochemical markers and maternal age. Since Ii of the 22 Dow~ syndrome cases were from older pregnancies (>=35 years old), rates were recalculated using the USA age distribution of live births to get a more representative estimate of false positives a n d d e t e c t i o n efficiency. I~dBOLTS: The m e d i a n P A P P - A and FB level in DS cases wan 0.385 and 2.09 MoM, respectively. At a 5.0% false positive rate 15 (68.2%) DS canes were detected. Using the age distribution of live births, 63% of cases could be expected to be detected at a 5.0% false positive rate. CONCLUSION: First trimester FB/PAPP-A screening for DS can achieve detection rates an high as those associated with AFP/hCG or AFP/hCG/uE3 screening in the second trimester. Prospective studies are needed to further assess first trimester screening.
20 COMPARISON OF MULTIPLE MARKER SCREENING WITH ELECTIVE AMNIOCENTESIS FOR DETECTION OF ANEUPLOIDY IN WOMEN > 35. K. Wenstrom, R. Desai x, J. Owen, M. DuBard x, L. Boots x. The University of Alabama at Birmingham. OBJECTIVE: To compare the multiple marker screening test (MMST) with elective amniocenteeis for the detection of fetal Down Syndrome (DS)and other aneuploidies in women age 35 and older. STUDY DESIGN: Our data base included test results from a total of 1,609 women age -> 35 with singleton pregnancies. Fourteen cases of DS and 12 other aneuploidies were diagnosed in 1582 women; 27 retrospective DS cases were also included. All women had both the MMST, (Maternal serum alphafetoprotein, human chorionic gonadotrophin, unconjugated estriol, and maternal age) and a genetic amniocentesis. A D S risk >_ 1:190 was considered screen positive. In addition, an algorithm to detect Trisomy 18 was employed. A positive trisomy 18 screen was defined as MSAFP < 0.75 MOM, hCG < 0.55 MOM and estriol < 0.6 MOM. RESULTS: The MMST screen positive rate was 27.8% (447/1609). Thirty-two of the 41 DS cases had positive screens, for a detection rate of 78%. Two of the 3 cases of Trisomy 18 (66%) were identified by a positive Tdsomy 18 screen. However, the MMST detection rate for all aneuptoidies was only 68% (36/53). The 17 missed aneuploidies were trisomy 21 (n = 9), sex chromosome abnormalities (n = 4), trisomy 13 (n = 2), trisomy 22 (n = 1), and trisomy 18 (n = 1). One aneuploidy was detected for every 13 amniocenteses performed after MMST screening. After subtracting the 27 retrospective DS cases, one aneuploidy was detected for every 61 amnios performed for maternal age in the original 1582 women. CONCLUSIONS: The MMST fails to detect approximately 32% of all fetal aneuploidies in women >_ age 35. The aneuploidies missed by the MMST include diagnoses for which survival with handicap might be anticipated. The current practice of offering elective amniocentesis to these women should be continued.
21 NORMAL NUCHAL THICKNESS IN THE MIDTRIMESTER INDICATES REDUCED RISK OF DOWN SYNDROME IN PREGNANCIES WITH ABNORMAL TRIPLE SCREEN. R. Bahado-Sin~h. I. Goldstein X, B. Uerpalrojkit x, J. A. Copel, M. Mahoneyx, A. Banmgarten x. Yale University School of Medicine, New Haven, CT. OBJECTIVE: Biochemical screening for Down syndrome (DS) has a poor positive predictive value. After a normal ultrasound, many patients with abnormal biochemical screen decline amniocentesis. They assume that negative ultrasound findings reduce overall risk. To test this hypothesis, we studied the effect of normal nuchal thickness (NT) on risk among patients with abnormal biochemical screening for DS. STUDY DESIGN: NT was measured prospectively in 465 mid trimester pregnancies (15-21 weeks), undergoing amniocentesis for abnormal ( > 1/270) risk of DS based on triple screen. NT'e_6nun was considered abnormal. The incidence of DS in the normal NT group was compared to the abnormal NT group. Chi-square analysis and Fisher's exact test were employed. RESULTS: The overall prevalence of DS was 6/465. A normal NT had high specificity (99%). With a normal nuchal thickness the risk of DS was 1/152 compared to 1/2.7 with abnormal NT (p=0.0007). With an abnormal nuchal thickness the risk ratio of having DS is 28.05 (95% CI 9.008, 86.6, p=0.0004). CONCLUSION: Nuchal thickness measurement is the single most sensitive biometric parameter for DS screening in a low risk population. Among patients with an abnormal triple screen, normal NT represented a 50 fold reduction in risk compared to cases with increased NT. This information can be used to further refine risk estimates of DS based on biochemical screening.
SIGNIFICANCE OF FETAL RENAL PELVIS DILATATION DETECTED 22 BY SONOGRAPHY. H. How, F. Tsung," K. Berg-Pass, x L. Goldsmith," J. Spinna'to'~ Dept.of Ob/Gyn, Univ.of Louisville, Louisville, KY. OBJECTIVE: To re-evaluate the existing threshold criteria (Corteville) for the diagnosis and follow-up, both prenatally and postnatally, of congenital hydronephrosis (CH) and to determine the degree of fetal renal pelvis dilatation that best predicts ,~ostnatal renal compromise. TUDY DESIGN: Within a 26-month period, using the criteria for CH as defined by Corteville et al, 112 fetuses (98 prospectively and 14 retrospectively identified) with renal pelvis anteroposterior diameters (APD) of > 4 mm prior to 33 weeks gestation and >7mm after 33 weeks gestation were studied. These fetuses were followed by serial prenatal sonography and then postnatally at 48 hours to 2 weeks and > 3 months of life. Intravenous pyelography, renal scintigrap~'y, and voiding cystourethrography were performed when necessary. Statistical analysis was carried out using the Chi-squared test, Fisher's exact test, cross tabs and receiver operating characteristic (ROC) curve. RESULTS: The incidence of CH in our study was 1.4% (98/7304). There was a predominance of affected males 77.7% (n =87) vs. 22.3% females (n=25); RR of 1.55 (CI 1.25- 1.92). Using a ROC curve, we found that a renal pelvis APD of :>9 mm detected at any time during gestation had a better positive predictive value for an abnormal postnatal scan than Corteville's criteria (35% vs. 18%). The sensitivity, specificity, and negative predictive value using renal pelvis APD of :>9 mm for detection of postnatal hydronephrosis was 85%, 66%, and 95% respectively. Using Corteville's criteria 82% (92/112) fetuses identified as abnormal had no significant neonatal genito-urinary tract pathology. None of the fetuses required early delivery as a result of deteriorating nito-urinary tract findings. NCLUSIONS: Our data suggest that most fetuses with sonographically detected renal pelvis APD of < 9 mm at any time during gestation did not have significant postnatal sequelae, and thus, do not require expensive serial antenatal sonographic surveillance. For fetuses with renal pelvis APD of >- 9 ram. a follow-up prenatal ultrasound at mid-third trimester appears to be adequate surveillance. All fetuses meeting Corteville's criteria should have a follow-up postnatal renal ultrasound within 1-3 months of age.