Christine Walters

Longitudinal Assessment of Endocervical Canal Length Between 15 and 24 Weeks’ Gestation in Women at Risk for Pregnancy Loss or Preterm Birth☆

Abstract Objective: To determine the weekly cervical shortening rates of the endocervical canal between 15 and 24 weeks’ gestation in women at risk for pregnancy loss or spontaneous preterm birth. Methods: We performed a retrospective cohort study of transvaginal sonographic measurements of the endocervical canal length done at least twice between 15 and 24 weeks’ gestation in women at risk for pregnancy loss and spontaneous preterm birth. The ultrasound diagnosis of cervical incompetence was defined as progressive shortening of the endocervical canal length to 2 cm or less either spontaneously or after application of transfundal pressure. Multivariable linear regression models were developed to determine the weekly crude rate of endocervical canal length shortening rates in cases of competent cervices and incompetent cervices, with incompetent cervices further stratified as those diagnosed at 15–19 weeks’ and 20–24 weeks’ gestation. Comparisons of the models for weekly rate of endocervical canal length shortening were performed. Results: The endocervical canal lengths were measured in 61 women (180 measurements) who did not develop ultrasound evidence of cervical incompetence and 28 women (103 measurements) who had ultrasound evidence of cervical incompetence. Between 15 and 24 weeks’ gestation, competent cervices had a nonsignificant rate of endocervical canal length shortening (−0.03 cm/week). During this period in gestation, incompetent cervices had significantly greater endocervical canal length shortening (−0.41 cm/week, P Conclusion: Weekly rates of endocervical canal length shortening were established, which may be useful for detecting and managing cervical incompetence in high-risk women examined with cervical sonography.

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 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.