Lami Yeo

Preterm premature rupture of membranes, intrauterine infection, and oligohydramnios: risk factors for placental abruption.

OBJECTIVE: To examine whether preterm premature rupture of membranes (PROM), intrauterine infection, and oligohydramnios are risk factors for placental abruption. METHODS: Data for this retrospective cohort study were derived from the 1988 National Maternal and Infant Health Survey (N = 11,777). Association between abruption and these clinical risk factors was expressed as relative risk (RR) and 95% confidence interval (CI), with multivariate adjustment for potential confounders. RESULTS: The overall incidence of abruption was 0.87%. The risk of abruption was 3.58-fold higher (95% CI 1.74–7.39) among women with preterm PROM (2.29%) compared with women with intact membranes (0.86%). The rates of abruption among women with and without intrauterine infection were 4.81% and 0.83%, respectively (RR 9.71, 95% CI 3.23–29.17). However, oligohydramnios was not associated with abruption (1.46% compared with 0.87%; RR 2.09, 95% CI 0.92–5.31). Compared with women with intact membranes, the RR for abruption among preterm PROM and whose membranes were ruptured for 24–47 hours and 48 hours or more before delivery, respectively, were 2.37 (95% CI 0.99–9.09), and 9.87 (95% CI 3.57–27.82). When preterm PROM was accompanied by intrauterine infections, the RR for abruption was 9.03 (95% CI 2.80–29.15) compared with women with intact membranes and no infections. Similarly, preterm PROM accompanied by oligohydramnios conferred over a 7.17-fold risk (95% CI 1.35–38.10) for abruption compared with women with neither of these 2 conditions. CONCLUSION: Women presenting with preterm PROM are at increased risk of developing abruption, with the risk being higher either in the presence of intrauterine infections or oligohydramnios. Physicians managing patients with preterm PROM should be aware that these patients are at increased risk of developing abruption after 24 hours following preterm PROM. LEVEL OF EVIDENCE: II-2

Absent nasal bone in the prenatal detection of fetuses with trisomy 21 in a high-risk population.

OBJECTIVE To estimate the usefulness of absent nasal bone by ultrasound in the prenatal detection of second-trimester fetuses with trisomy 21. METHODS This was a matched case–control study of sonograms from January 1, 1997 to April 30, 2002. Genetic sonograms and facial profile pictures of all fetuses that were subsequently proven to have trisomy 21 were reviewed (study group). A control group was identified during the same study period by using a 4-to-1 ratio matching for gestational age at the time of the ultrasound examination. The sensitivity and specificity of absent fetal nasal bone for trisomy 21 were determined, and overlap with other ultrasound aneuploidy markers was assessed. RESULTS Forty fetuses were identified with trisomy 21; in 29 (72.5%) a facial profile had been obtained. Of the 160 controls, 102 (64%) had facial profiles documented. Of the 29 fetuses with trisomy 21 with facial profile available, 12 had absent nasal bone (sensitivity 41%). None of the 102 control fetuses with facial profiles available had absent nasal bone (specificity 100%). The sensitivity of genetic ultrasound was increased from 83% (24 of 29) to 90% (26 of 29) by adding absent nasal bone to the other ultrasound aneuploidy markers. CONCLUSION In the second trimester of pregnancy, absent nasal bone has a sensitivity of 41% and a specificity of 100% in detecting fetal trisomy 21. Absent fetal nasal bone may be added to the list of ultrasound aneuploidy markers evaluated during a genetic sonogram.

Prenatal Detection of Fetal Trisomy 18 Through Abnormal Sonographic Features

Objective. To describe the prenatal detection of fetal trisomy 18 through abnormal sonographic features and to determine the sensitivity of sonographically detecting fetuses with trisomy 18. Methods. All genetic and cytogenetic records of fetuses with trisomy 18 were reviewed retrospectively (1992‐2002). From these, singleton fetuses who had prenatal sonography at our unit were identified. The maximal numbers of individual abnormalities from 1 sonographic examination (not limited to type of organ system) were recorded. Each abnormality was classified as major, minor, or “other,” and each organ system was classified as abnormal only once, regardless of the number of individual abnormalities identified in that system. The sensitivity of sonography in detecting abnormalities of trisomy 18 was determined. Results. Of 38 fetuses identified with trisomy 18, all had 4 or more prenatally detected sonographic abnormalities (sensitivity of sonographic detection of fetuses with trisomy 18, 100%). The median number of abnormalities per examination was 8 (range, 4‐19). Sonographically detected major abnormalities were cardiac (84%; n = 32), central nervous system (87%; n = 33), gastrointestinal (26%; n = 10), and genitourinary (16%; n = 6). Sonographically detected minor abnormalities were short ear length below the 10th percentile for gestational age (96%; n = 26/27), upper extremities and hands (95%; n = 36), lower extremities and feet (63%; n = 24), and face (53%; n = 20). Fifty percent (19 of 38) had choroid plexus cysts identified, but this was never an isolated finding. Conclusions. In experienced hands, the sensitivity of detecting fetal trisomy 18 on prenatal sonography is 100%, and all cases will have multiple anomalies visualized.

Value of a complete sonographic survey in detecting fetal abnormalities: correlation with perinatal autopsy.

Objective. To determine the sensitivity of using a complete anatomic sonographic survey in detecting fetal abnormalities via correlation with perinatal autopsy results. Methods. All perinatal autopsies (1994–2001) with positive findings for at least 1 fetal abnormality and performed by a single perinatal pathologist at our institution were retrospectively reviewed. From these cases, singleton fetuses who received prenatal sonography solely in our unit were identified. The sensitivity of sonography in detecting anomalous fetuses as well as fetal abnormalities and abnormalities by organ system was determined. Abnormalities were classified as major or minor. In addition, findings from sonography and autopsy were compared, and their correlation was assigned to 1 of 3 categories. Results. Of 88 fetuses identified, 85 had 1 or more abnormal structural sonographic findings (sensitivity for fetuses with anomalies, 97%). A total of 372 separate abnormalities were found on autopsy; of the 299 major and 73 minor abnormalities, prenatal sonography showed 224 (75%) and 13 (18%), respectively. There was either complete agreement or only minor differences between sonographic and autopsy findings in 57 (65%) of 88. The sensitivity of sonography in identifying abnormalities was greater than 70% in these systems: central nervous system, cardiac system, urinary system, extremities, genitalia, ribs, and hydrops. Conclusions. In experienced hands, sonography has 97% sensitivity in detecting anomalous fetuses when compared with perinatal autopsy results. Although the sensitivity of sonography in detecting major fetal abnormalities is 75%, the sensitivity for minor abnormalities is poor, even when using a complete anatomic sonographic survey. Although it has limitations, this type of survey is invaluable for both patients and physicians in diagnosing fetal abnormalities.

Prenatal Sonographic Findings Associated With Nonmosaic Trisomy 9 and Literature Review

T risomy 9 was first reported in 1973 through blood lymphocyte testing in a newborn male with multiple congenital anomalies. 1 Since that time, only approximately 30 cases of mosaic or nonmosaic trisomy 9 have been reported 2 ; therefore, this is a relatively rare chromosomal abnormality, constituting only 2.7% of all trisomic cases. 3 Nonmosaic or complete trisomy 9 is a lethal diagnosis, with most fetuses dying prenatally or during the early postnatal period. Those who survive usually have mosaic trisomy 9 and have severe motor and mental deficiencies. With mosaic trisomy 9, the prevalence and severity of malformations and mental deficiency correlate with the percentages of trisomic cells in different tissues. 4 4 Because most complete trisomy 9 cases end in spontaneous abortion in the first trimester, there is a paucity of reports regarding the prenatal sonographic findings of complete trisomy 9. To our knowledge, only 7 cases of nonmosaic trisomy 9 that were specifically detected on prenatal sonography have been reported in the literature: first trimester (n = 2), second trimester (n = 2), and third trimester (n = 3). 3,5-9 There are distinct features associated with complete trisomy 9. Clinical and sonographic findings that have been described include intrauterine growth restriction, central nervous system abnormalities, cranial and facial anomalies, skeletal defects, congenital heart defects, and urogenital abnormalities. 6.8 8 The purpose of this report is to describe the prenatal sonographic findings in a second-trimester fetus with trisomy 9 and also to review the sonographic findings of all published cases of nonmosaic trisomy 9 that were specifically detected on sonography.

Second-trimester genetic sonography in patients with advanced maternal age and normal triple screen

OBJECTIVE To estimate the value of second‐trimester genetic sonography in detecting fetal Down syndrome in patients with advanced maternal age (at least 35 years) and normal triple screen. METHODS Since July 1999, a prospective collection and recording of all individual triple screen risks for fetal Down syndrome was initiated for all patients with advanced maternal age presenting in our ultrasound unit for second‐trimester genetic sonography. Genetic sonography evaluated the presence or absence of multiple aneuploidy markers. Outcome information included the results of genetic amniocentesis, if performed, and the results of pediatric assessment and follow‐up after birth. RESULTS By June 2001, 959 patients with advanced maternal age and normal triple screen were identified. Outcome information was obtained in 768 patients. The median risk for fetal Down syndrome based on maternal age was 1:213 (range 1:37–1:274). The median risk for fetal Down syndrome based on triple screen results was 1:1069 (range 1:275–1:40,000). A total of 673 patients had normal genetic sonography, and none (0%) had Down syndrome; 95 had one or more aneuploidy markers present, and four (4.2%) had fetuses with Down syndrome. The triple screen risks for these four fetuses ranged from 1:319 to 1:833. CONCLUSION This study suggests that patients with advanced maternal age and normal genetic sonography carried very little risk for Down syndrome. The use of genetic sonography may increase the detection rate of fetal Down syndrome in this group of pregnant women.

Prenatal Detection of Fetal Aneuploidy by Sonographic Ear Length

Objective. To determine the usefulness of a fetal ear length nomogram in the prenatal detection of fetal aneuploidy and to determine whether ear smallness in cases of aneuploidy is a primary or secondary event. Methods. Ear lengths of 447 singleton fetuses (October 1996 to October 1997) were prospectively evaluated between 14 and 41 weeks to establish a nomogram created by modeling the mean and SD separately. Records of aneuploid fetuses were retrospectively reviewed, and their ear lengths were plotted against the nomogram to determine detection rates, with ear length in or below the 10th and 50th percentiles for a given gestational age and biparietal diameter used as abnormal cutoffs. Results. The nomogram for fetal ear length measurements provided sufficient data to derive the 10th, 50th, and 90th percentiles on the basis of gestational age and biparietal diameter. The ear length of euploid fetuses was significantly correlated with gestational age (R2 = 0.96; P < .001) and biparietal diameter (R2 = 0.95; P < .001). From 96 aneuploid fetuses identified, 63 had ear lengths in or below the 10th percentile for gestational age (sensitivity, 66%). When using ear length against biparietal diameter, the sensitivities for all aneuploid fetuses for cutoffs at or below the 10th and 50th percentiles were 43% (40 of 93) and 83% (77 of 93), respectively. Conclusions. Most aneuploid fetuses have sonographically small ears (≤10th percentile for gestational age). This smallness is not entirely related to overall small fetal size, but in almost half the cases, the fetal ear length is disproportionately smaller than the biparietal diameter.

The clinical significance of absence of end-diastolic velocities of the umbilical artery detected in the severely preterm fetus

Objective: To determine whether there is a gestational age cutoff at the time of diagnosis of AEDV of the umbilical artery Doppler waveform that is associated with nearly zero perinatal survival. Methods: Over an 8-year period we identified and compared the outcomes of pregnancies in which AEDV of the umbilical artery Doppler waveform was detected between 19–24 and 25–28 weeks of gestation. All fetuses had normal structure and karyotypes. Small for gestational age (SGA) was defined as less than the 10th percentile for gestational age based on Brenner’s curve. Values are reported in median (range). Results: There were no survivors among the 27 cases identified at 19–24 weeks of gestation: 5 terminations for severe-SGA fetus (birth weight 336 [130–430] grams), 3 terminations for severe preeclampsia and SGA fetus, 12 fetal deaths, 7 neonatal deaths, and 10 cases (46%) of pregnancy-induced hypertension/preeclampsia (PIH/PE). All 8 cases detected at 25–28 weeks of gestation resulted in neonatal survival at discharge (P <0.0001), and there were 2 cases (25%) of PIH/PE (P = 0.54). Conclusion: In this study, AEDV of the umbilical artery Doppler waveform identified at less than 25 weeks of gestation is associated with a 100% perinatal mortality rate and a high rate of PIH/PE. This information should be incorporated into the counseling and management of women in this clinical setting.

Persistent Funic Presentation Resulting From Marginal Cord Insertion into a Low-Lying Placenta

Cord prolapse is one of the most feared complications of pregnancy and is associated with high perinatal mortality and morbidity. While cord prolapse may be associated with malpresentation, unengagement of the presenting part, and prematurity, very often it occurs without warning. The advent of ultrasound has afforded the physician the ability to prenatally detect funic presentation, generally considered a precursor of cord prolapse1–4. This allows Cesarean delivery prior to the onset of labor, potentially avoiding cord prolapse, and therefore preventing the perinatal morbidity and mortality associated with this complication1,2. Recent studies, however, have suggested that funic presentation detected prenatally does not always result in cord prolapse in labor, since funic presentation not infrequently resolves spontaneously3,4. The challenge therefore is identifying which cases of prenatally diagnosed funic presentation are likely to persist until labor. We describe a case of funic presentation associated with a marginal cord insertion into the lower edge of a low-lying posterior placenta. A 33-year-old female in her fifth pregnancy had a sonogram at 20 weeks’ gestation that revealed a complete placenta previa. She had previously had four uncomplicated pregnancies that had delivered vaginally at term. Follow-up sonography at 27 weeks of gestation showed a posterior low-lying placenta, with its lower edge 1.5 cm from the internal os. Free loops of umbilical cord were noted overlying the cervix. The cord insertion was noted to be into the lower aspect of the placenta, but the insertion was not velamentous. The cervix measured 5 cm in length and was closed, without funneling or dynamic changes. Sonography was performed every 3 weeks to monitor the placenta. At each of the sonographic examinations the free loops of cord were consistently noted to overlie the cervix. At 34 + 4 weeks, sonography revealed the placenta to be posterior, with its lower edge 1.9 cm from the internal cervical os. Free loops of cord ran over the cervix, and the placental cord insertion was noted to be 2 cm from the lower placental edge (Figures 1 and 2). Fetal growth was appropriate for gestational age. Fetal heart tracing was reactive with accelerations. However, there were recurrent, shallow, variable, fetal heart rate decelerations. A Cesarean delivery was performed at 35 + 2 weeks. A live, male infant was delivered weighing 2400 g with Apgar scores of 8 and 9 at 1 and 5 min, respectively. The infant was admitted to the neonatal unit, had an uncomplicated hospital course and was discharged home on the seventh day of life. The marginal cord insertion was confirmed by placental examination after delivery. Figure 1 Sonogram demonstrating the free loops of cord in the lower uterine segment (small arrows). The large arrow points to the internal cervical os, and the arrowhead to the lower placental edge. cx, cervix; h, head; p, placenta.

The role of ultrasound in prenatal detection of chromosomal abnormalities

Fetal aneuploidy is the leading cause of pregnancy loss. At least 95% of chromosomally abnormal conceptions are lost before term. Over the years, it has become common to offer genetic amniocentesis or chorionic villus sampling to all women who have increased risk of fetal chromosomal abnormalities. However, due to its invasive nature and associated risks, the practice of offering routine invasive testing to all high-risk pregnant women has been challenged. Owing to evolving improvement in high-quality sonographic imaging, it has become apparent that many chromosomal abnormalities that are associated with fetal structural abnormalities or aneuploidy markers are capable of being detected by ultrasound. Since fetuses with trisomies 18 and 13 have many major structural abnormalities, ultrasound has a high sensitivity for detecting them. On the other hand, over the years, investigators have been looking for sonographic markers to increase the detection rate for Down syndrome on prenatal sonography. This has le...