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629 The effect of maternal position on cervical length and dynamic shortening during pregnancy
SMFM Abstracts S251
Volume 185, Number 6 A l n J Obstet Gynecol 629
THE EFFECT OF MATERNAL POSITION ON CERVICAL LENGTH AND DYNAMIC S H O R T E N I N G D U R I N G PREGNANCY KIRK RAMIN~, AMY MEATH, MD 1, ROBERT ROSENQUIST 1, TAMMY FREIMUND 1, PATRICK RAMSEV2; 1Mayo Clinic, Obstetrics a n d Gynecology, Rochester, MN; 2University of Alabama at Birmingham, Obstetrics a n d Gynecology, Birmingham, AL OBJECTIVE: To characterize the efI;ect of maternal position on cervical length a n d dynamic shortening changes during pregnancy. STUDY DESIGN: Thirty-two heahhy gravidas (12 singleton, 13 twin, a n d 7 triplet pregnancies) between 16 a n d 18 weeks gestation were prospectively enrolled in this longitudinal investigation of cervical length. Serial cervical ultrasound assessments were made weekly nsing a standardized transperineal sonographic technique u n d e r 3 study conditions: 1) supine, 2) supine with Valsalva maneuver, 3) standing. Cervical length, internal os dimneter, a n d presence of cervical funneling were assessed u n d e r each study condition. RESULTS: In the 32 women participating in this investigation, a total of 1286 cervical s o n o g r a p h i c m e a s u r e m e n t s were made. Overall, c h a n g i n g maternal position from supine to a standing position resulted in a slight nonsignificant change (-0.1 + 0.4 into; 95% C1-0.7 to d.8) in cervical length ( P = .85). In contrast, m e a s u r e m e n t of cervical length d u i i n g Valsalva maneuver resulted in a significant reduction in cervical length when c o m p a r e d to the cervical length measured in a supine (-1.0 ± 0.3 ram; 95% C1-0.4 to -1.6) (P = .0009) a n d standing position (-0.9 ± 0.4; 95% C1-0.2 to -1.6) (P = .009). The observed dynamic s h o r t e n i n g c h a n g e s were similar across gestation, irrespective of singleton, twin or triplet gestation. Neither standing n o r Valsalva m a n e u v e r has a significant effect on internal os diameter or the presence of funneling. CONCLUSION: Cervical length m e a s u r e m e n t s m a d e in a s t a n d i n g position are comparable to those measured while supine. In contrast, cervical lengths measured during a Valsalva maneuver are significantly shorter than those m a d e in either the supine or standing position. F u r t h e r research is needed to further characterize these dynamic shortening changes as potential markers for impaired cervical competency in women at risk for spontaneous preterm delivery.
631
ULTRASOUND ASSESSMENT OF AMNIOTIC FLUID VOLUME FOR THE DIAGNOSIS OF OLIGOHYDRAMNIOS GAYLE OLSON l, EVERETT MAGANN e, RADEK BUKOWSKI 3, J O H N MORRISON ~, JAMES MARTIN JR 4, GEORGE SAADES; lUniversity of Texas Medical Branch, Obstetric a n d Gynecology, Galveston, TX; 3University of Mississippi Medical Center, Obstetrics a n d Gynecology,Jackson, MS; ~University of Texas Medical Branch, Obstetrics a n d Gynecology, Galveston, TX: 4University of Mississippi Medical Center, G r a d u a t e Medical Education, Jackson, MS: 5University of Texas Medical Branch at Galveston, Obstetrics and Gynecology, Galveston, TX OBJECTIVE: Color Doppler (CD) is often used to exclude the umbilical c o r d d u r i n g m e a s u r e m e n t of the anmiotie fluid index (AFI) a n d deepest vertical pocket (DVP). O u r objective was to c o m p a r e different nmthods of ultrasound evaluation of amniotic fluid in predicting oligohydrmnnios. STUDY DESIGN: AF1 and DVP were evaluated in 76 gravidas (gestational age 37.1 -+ 2.4 weeks) using both CD a n d GS techniques. Thereafter, AFV was estimated by the dye-dilution technique after removal of an aliquot for fetal lung maturity studies. The relationship with a n d prediction of a measured AFV < 500ml a n d < 400rot was evaluated for AFI < 5cm by CD or GS, DVP < 2cm by CD or GS, a n d AFI <5%ile compared to n o m o g r a m s based on measurements o b t a i n e d using CD (Zlamik et al) or GS (Moore et al) measurements. Statistical analysis was p e r f o r m e d using Mann2Whitney test, Chi-squared test, a n d ROC curve (significance: P< .05). RESULTS: There were no differences in the AFI or DVP values measured with either CD or GS between those with a n d without oligohydramnios by either cutoff. Similarly, there was no difference in the proportion of abnormal AFI or DVP values measured with either CD or GS between those with a n d without oligohydramnios by eitller cutoff. None of the ultrasound estimates were significantly predictive of oligohydramnios by either cutoff. The sensitivity for CD-AFI <5%ile using CD-based n o m o g r a m was 29% c o m p a r e d with 23% for GS-AFI <5%ile using GS-based n o m o g r a m , a n d b o t h were significantly lower than the 56% sensitivity for CD-AFI <5%ile using GS-based nomograms. No differences in specificities were n o t e d (82% vs 91% vs 73%). CONCLUSION: Regardless of CD or GS use, all ultrasound methods of amniotic fluid assessment are p o o r predictors of oligohydranmios. The highest sensitivity was obtained w h e n AFI was m e a s u r e d with CD a n d c o m p a r e d to n o m o g r a m derived using GS.
630
COMPARISON OF TWO METHODS FOR CERVICAL LENGTH MEASUREMENT GAYLE OLSON l, J O H N BARTON 2, GEORGE SAADE l, GARY HANKINS 3, GARLAND ANDERSON4; ]University of Texas Medical B r a n c h at Galveston, Obstetrics a n d Gynecology, Galveston, TX; eCentral Baptist Hospital, Lexington, KY: ~University of Texas Medical Branch at Galveston, Obstretics & Gynecology, Galveston, TX: 4University of Texas Medical Branch at Galveston, Maternal Medicine, Galveston, TX OBJECTIVE: Cervical length can be measured using ultrasound either along a straight line from internal to external os, or following the curvature of the cervical canal. O u r objective was to deternfine if these 2 methods are equivalent. STUDY DESIGN: 100 gravidas with an indication for transvaginal ultrasound also h a d the cervical length measured on the same still image by two methods: 1) straight line from internal to external os, 2) a line following the curvature of the cex':ical canal. In all cases, the U-ansducer was first inserted to visualize the entire cervical canal alter which it was withdrawn until the image blurred then gently reapplied. Kohnogorov-Smirnov, Wilcoxon Signed Rank, Pearson correlation, Multiple linear regression analysis a n d McNemar's tests were used for analysis (significance: P < .01). Data presented as median [interquartile range] or number. RESULTS: Median gestational age was 20 [18-25] weeks. Cervical length was significantly shorter using a straight line versus following the curvature of the.cervical canal (3.75 [3.134.30] vs 3.95 [3.294.69] cm; P < .001). Cetwical length measurements < 2.5cm were more frequently n o t e d with the straight line vs cmazature of the cervical canal method (10/100 vs 5/100; P < .001). The dit~erences in measureinents between the 2 metlmds did not correlate with gestational age ( P - .09). Multivariate analysis confirmed that the effect of the m e t h o d on cervical length m e a s u r e m e n t r e m a i n e d significant after controlling for gestational age (P< .05). CONCLUSION: M e a s u r e m e n t of the cervix a l o n g the course of the endocervical canal overestimates its length a n d may underestimate tlae risk for p r e t e r m delivelT when based on studies using the single straight line measurement. Nomograms a n d risk assessments should be developed for each method.
632
CERVICAL DYNAMICISM: COMPARISON OF REAL-TIME CERVICAL S H O R T E N I N G W I T H UTERINE ACTIVITY SHERI JENKINS 1, JAMES KURTZMAN 2, WENDY' BREWSTER3; 1University of Calitorrlia, Irvine, O b / G y n , Irvine, CA; eUniversity of CaliIornia, Irx4ne, Ob/G~aa, Laguna Hills, CA; 3University of California, Irvine, O b / G y n , Orange, CA OBJECTIVE: To c o m p a r e real-time cervical s h o r t e n i n g d u r i n g transvaginal u l t r a s o u n d (US) will, u t e l i n e activity in p r e t e r m patients with a n d without symptoms of preterm labor (PTL). STUDY DESIGN: Transvaginal US was p e r f o r m e d on 147 patients from 24 to 34 weeks' estimated gestational age (EGA), including 84 patients with PTL symptoms a n d 63 asymptonlatic patients. Cervical lengths were measured in each patient at l-minute intervals over a 10-minute observation period. Patients were continuously monitored tot uterine contractions or irritability (frequent, low-grade contractions) d u r i n g the US exam. "Cervical dynamicism" was defined as real-time cervical length changes of > 6ram as per previous data from this laboratoly. The incidence of cervical dynamicism was c o m p a r e d with the presence or absence of uterine activity. Cervical length during contractions was also c o m p a r e d with the mean initial length a n d mean nadir length. RESULTS: The mean EGA of the symptomatic group at examination was slightly greater than the asymptomatic g r o u p (28.9 vs. 27.7 weeks' gestation, P = .02). Celwical dynamicism was f o u n d to be associated with uterine contractions (OR 5.6, 95%CI 2.6-12), but not irritability (OR 1.2, 95%CI 0.6-2.6). The mean cervical length during contractions was shorter than the initial cervical length (2.91 vs. 3.26, P < .001). T h o u g h the m i n i n m m cervical length d u r i n g contractions was not as short as the nadir length, it was closer than any other parameter studied (2.80 vs. 2.65cm, P < .001). CONCLUSION: Preterm patients exhibiting cervical dynamicism by US have more uterine contractions than patients without these cervical findings. Although the nadir cervical length did not always occur during a contraction, the cervix often s h o r t e n e d f r o m its initial length when contractions were present. As such, a single cervical length m e a s u r e m e n t in a patient with intermittent contractions may fail to d e m o n s t r a t e cervical s h o r t e n i n g that might occur with continued observation.
Volume 185, Number 6 A l n J Obstet Gynecol 629
THE EFFECT OF MATERNAL POSITION ON CERVICAL LENGTH AND DYNAMIC S H O R T E N I N G D U R I N G PREGNANCY KIRK RAMIN~, AMY MEATH, MD 1, ROBERT ROSENQUIST 1, TAMMY FREIMUND 1, PATRICK RAMSEV2; 1Mayo Clinic, Obstetrics a n d Gynecology, Rochester, MN; 2University of Alabama at Birmingham, Obstetrics a n d Gynecology, Birmingham, AL OBJECTIVE: To characterize the efI;ect of maternal position on cervical length a n d dynamic shortening changes during pregnancy. STUDY DESIGN: Thirty-two heahhy gravidas (12 singleton, 13 twin, a n d 7 triplet pregnancies) between 16 a n d 18 weeks gestation were prospectively enrolled in this longitudinal investigation of cervical length. Serial cervical ultrasound assessments were made weekly nsing a standardized transperineal sonographic technique u n d e r 3 study conditions: 1) supine, 2) supine with Valsalva maneuver, 3) standing. Cervical length, internal os dimneter, a n d presence of cervical funneling were assessed u n d e r each study condition. RESULTS: In the 32 women participating in this investigation, a total of 1286 cervical s o n o g r a p h i c m e a s u r e m e n t s were made. Overall, c h a n g i n g maternal position from supine to a standing position resulted in a slight nonsignificant change (-0.1 + 0.4 into; 95% C1-0.7 to d.8) in cervical length ( P = .85). In contrast, m e a s u r e m e n t of cervical length d u i i n g Valsalva maneuver resulted in a significant reduction in cervical length when c o m p a r e d to the cervical length measured in a supine (-1.0 ± 0.3 ram; 95% C1-0.4 to -1.6) (P = .0009) a n d standing position (-0.9 ± 0.4; 95% C1-0.2 to -1.6) (P = .009). The observed dynamic s h o r t e n i n g c h a n g e s were similar across gestation, irrespective of singleton, twin or triplet gestation. Neither standing n o r Valsalva m a n e u v e r has a significant effect on internal os diameter or the presence of funneling. CONCLUSION: Cervical length m e a s u r e m e n t s m a d e in a s t a n d i n g position are comparable to those measured while supine. In contrast, cervical lengths measured during a Valsalva maneuver are significantly shorter than those m a d e in either the supine or standing position. F u r t h e r research is needed to further characterize these dynamic shortening changes as potential markers for impaired cervical competency in women at risk for spontaneous preterm delivery.
631
ULTRASOUND ASSESSMENT OF AMNIOTIC FLUID VOLUME FOR THE DIAGNOSIS OF OLIGOHYDRAMNIOS GAYLE OLSON l, EVERETT MAGANN e, RADEK BUKOWSKI 3, J O H N MORRISON ~, JAMES MARTIN JR 4, GEORGE SAADES; lUniversity of Texas Medical Branch, Obstetric a n d Gynecology, Galveston, TX; 3University of Mississippi Medical Center, Obstetrics a n d Gynecology,Jackson, MS; ~University of Texas Medical Branch, Obstetrics a n d Gynecology, Galveston, TX: 4University of Mississippi Medical Center, G r a d u a t e Medical Education, Jackson, MS: 5University of Texas Medical Branch at Galveston, Obstetrics and Gynecology, Galveston, TX OBJECTIVE: Color Doppler (CD) is often used to exclude the umbilical c o r d d u r i n g m e a s u r e m e n t of the anmiotie fluid index (AFI) a n d deepest vertical pocket (DVP). O u r objective was to c o m p a r e different nmthods of ultrasound evaluation of amniotic fluid in predicting oligohydrmnnios. STUDY DESIGN: AF1 and DVP were evaluated in 76 gravidas (gestational age 37.1 -+ 2.4 weeks) using both CD a n d GS techniques. Thereafter, AFV was estimated by the dye-dilution technique after removal of an aliquot for fetal lung maturity studies. The relationship with a n d prediction of a measured AFV < 500ml a n d < 400rot was evaluated for AFI < 5cm by CD or GS, DVP < 2cm by CD or GS, a n d AFI <5%ile compared to n o m o g r a m s based on measurements o b t a i n e d using CD (Zlamik et al) or GS (Moore et al) measurements. Statistical analysis was p e r f o r m e d using Mann2Whitney test, Chi-squared test, a n d ROC curve (significance: P< .05). RESULTS: There were no differences in the AFI or DVP values measured with either CD or GS between those with a n d without oligohydramnios by either cutoff. Similarly, there was no difference in the proportion of abnormal AFI or DVP values measured with either CD or GS between those with a n d without oligohydramnios by eitller cutoff. None of the ultrasound estimates were significantly predictive of oligohydramnios by either cutoff. The sensitivity for CD-AFI <5%ile using CD-based n o m o g r a m was 29% c o m p a r e d with 23% for GS-AFI <5%ile using GS-based n o m o g r a m , a n d b o t h were significantly lower than the 56% sensitivity for CD-AFI <5%ile using GS-based nomograms. No differences in specificities were n o t e d (82% vs 91% vs 73%). CONCLUSION: Regardless of CD or GS use, all ultrasound methods of amniotic fluid assessment are p o o r predictors of oligohydranmios. The highest sensitivity was obtained w h e n AFI was m e a s u r e d with CD a n d c o m p a r e d to n o m o g r a m derived using GS.
630
COMPARISON OF TWO METHODS FOR CERVICAL LENGTH MEASUREMENT GAYLE OLSON l, J O H N BARTON 2, GEORGE SAADE l, GARY HANKINS 3, GARLAND ANDERSON4; ]University of Texas Medical B r a n c h at Galveston, Obstetrics a n d Gynecology, Galveston, TX; eCentral Baptist Hospital, Lexington, KY: ~University of Texas Medical Branch at Galveston, Obstretics & Gynecology, Galveston, TX: 4University of Texas Medical Branch at Galveston, Maternal Medicine, Galveston, TX OBJECTIVE: Cervical length can be measured using ultrasound either along a straight line from internal to external os, or following the curvature of the cervical canal. O u r objective was to deternfine if these 2 methods are equivalent. STUDY DESIGN: 100 gravidas with an indication for transvaginal ultrasound also h a d the cervical length measured on the same still image by two methods: 1) straight line from internal to external os, 2) a line following the curvature of the cex':ical canal. In all cases, the U-ansducer was first inserted to visualize the entire cervical canal alter which it was withdrawn until the image blurred then gently reapplied. Kohnogorov-Smirnov, Wilcoxon Signed Rank, Pearson correlation, Multiple linear regression analysis a n d McNemar's tests were used for analysis (significance: P < .01). Data presented as median [interquartile range] or number. RESULTS: Median gestational age was 20 [18-25] weeks. Cervical length was significantly shorter using a straight line versus following the curvature of the.cervical canal (3.75 [3.134.30] vs 3.95 [3.294.69] cm; P < .001). Cetwical length measurements < 2.5cm were more frequently n o t e d with the straight line vs cmazature of the cervical canal method (10/100 vs 5/100; P < .001). The dit~erences in measureinents between the 2 metlmds did not correlate with gestational age ( P - .09). Multivariate analysis confirmed that the effect of the m e t h o d on cervical length m e a s u r e m e n t r e m a i n e d significant after controlling for gestational age (P< .05). CONCLUSION: M e a s u r e m e n t of the cervix a l o n g the course of the endocervical canal overestimates its length a n d may underestimate tlae risk for p r e t e r m delivelT when based on studies using the single straight line measurement. Nomograms a n d risk assessments should be developed for each method.
632
CERVICAL DYNAMICISM: COMPARISON OF REAL-TIME CERVICAL S H O R T E N I N G W I T H UTERINE ACTIVITY SHERI JENKINS 1, JAMES KURTZMAN 2, WENDY' BREWSTER3; 1University of Calitorrlia, Irvine, O b / G y n , Irvine, CA; eUniversity of CaliIornia, Irx4ne, Ob/G~aa, Laguna Hills, CA; 3University of California, Irvine, O b / G y n , Orange, CA OBJECTIVE: To c o m p a r e real-time cervical s h o r t e n i n g d u r i n g transvaginal u l t r a s o u n d (US) will, u t e l i n e activity in p r e t e r m patients with a n d without symptoms of preterm labor (PTL). STUDY DESIGN: Transvaginal US was p e r f o r m e d on 147 patients from 24 to 34 weeks' estimated gestational age (EGA), including 84 patients with PTL symptoms a n d 63 asymptonlatic patients. Cervical lengths were measured in each patient at l-minute intervals over a 10-minute observation period. Patients were continuously monitored tot uterine contractions or irritability (frequent, low-grade contractions) d u r i n g the US exam. "Cervical dynamicism" was defined as real-time cervical length changes of > 6ram as per previous data from this laboratoly. The incidence of cervical dynamicism was c o m p a r e d with the presence or absence of uterine activity. Cervical length during contractions was also c o m p a r e d with the mean initial length a n d mean nadir length. RESULTS: The mean EGA of the symptomatic group at examination was slightly greater than the asymptomatic g r o u p (28.9 vs. 27.7 weeks' gestation, P = .02). Celwical dynamicism was f o u n d to be associated with uterine contractions (OR 5.6, 95%CI 2.6-12), but not irritability (OR 1.2, 95%CI 0.6-2.6). The mean cervical length during contractions was shorter than the initial cervical length (2.91 vs. 3.26, P < .001). T h o u g h the m i n i n m m cervical length d u r i n g contractions was not as short as the nadir length, it was closer than any other parameter studied (2.80 vs. 2.65cm, P < .001). CONCLUSION: Preterm patients exhibiting cervical dynamicism by US have more uterine contractions than patients without these cervical findings. Although the nadir cervical length did not always occur during a contraction, the cervix often s h o r t e n e d f r o m its initial length when contractions were present. As such, a single cervical length m e a s u r e m e n t in a patient with intermittent contractions may fail to d e m o n s t r a t e cervical s h o r t e n i n g that might occur with continued observation.