Ultraschall Med 2020; 41(04): 397-403
DOI: 10.1055/a-0865-1711
Original Article
© Georg Thieme Verlag KG Stuttgart · New York

Evaluation of Cervical Elastography Strain Pattern to Predict Preterm Birth

Evaluation von Kompressionsmustern in der Zervix-Elastografie zur Vorhersage einer Frühgeburt
Anna Gesthuysen
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Kerstin Hammer
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Mareike Möllers
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Janina Braun
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Kathrin Oelmeier de Murcia
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Maria Karina Falkenberg
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Helen Ann Köster
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Ute Möllmann
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Arrigo Fruscalzo
2   Department of Obstetrics and Gynecology, St. Franziskus-Hospital Ahlen, Germany
,
Eike Bormann
3   Institute of Biostatistics and Clinical Research, University-Hospital Münster, Germany
,
Walter Klockenbusch
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
,
Ralf Schmitz
1   Department of Obstetrics and Gynecology, University-Hospital Münster, Germany
› Author Affiliations
Further Information

Publication History

11 May 2018

20 February 2019

Publication Date:
25 March 2019 (online)

Abstract

Purpose To evaluate cervical elastography strain pattern as a predictive marker for spontaneous preterm delivery (SPTD).

Materials and Methods In this case-control study cervical length (CL) and elastographic data (strain ratio, elastography index, strain pattern score) were acquired from 335 pregnant women (20th – 34th week of gestation) by transvaginal ultrasound. Data of 50 preterm deliveries were compared with 285 normal controls. Strain ratio and elastography index were calculated by placing two regions of interest (ROIs) in parallel on the anterior cervical lip. The strain ratio was determined by dividing the higher strain value by the lower one. The elastography index was defined as the maximum of the strain ratio curve. Elastographic images were assigned a new established strain pattern (SP) score between 0 and 2 according to the distribution of strain induced by compression.

Results Elastography index, SP score and CL differed between preterm and normal pregnancies (1.61 vs. 1.27, p < 0.001; SP score value of “2”: n = 31 (62 %) vs. n = 36 (12.6 %), p < 0.001; CL 30.7 vs. 41.0 mm, p < 0.001; respectively). The elastography index and SP score were associated with a higher predictive potential than CL measurement alone (AUC 0.8059 (area under the curve); AUC 0.7716; AUC 0.7631; respectively). A combination of all parameters proved more predictive than any single parameter (AUC 0.8987; respectively).

Conclusion Higher elastography index and SP scores were correlated with an elevated risk of SPTD and are superior to CL measurement as a predictive marker. A combination of these parameters could be used as a “Cervical Index” for the prediction of SPTD.

Zusammenfassung

Ziel Evaluation von Kompressionsmustern (Strain-pattern, SP) mittels Zervix-Elastografie als prognostischer Marker für eine Frühgeburt.

Material und Methoden In dieser Fall-Kontroll-Studie wurden die Zervix-Länge und Elastografie-Daten (Kompressionsverhältnis (Strain-Ratio), Elastografie-Index und SP-Score) von 335 schwangeren Frauen (20. bis 34. Schwangerschaftswoche) mithilfe von transvaginalem Ultraschall erhoben. Die Werte von 50 Frühgeburten wurden mit den Werten von 285 Normalgeburten als Kontrollgruppe verglichen. Die Strain-Ratio und der Elastografie-Index wurden kalkuliert, indem 2 „regions of interest“ (ROIs) parallel auf der vorderen Zervix-Lippe platziert wurden. Die Strain-Ratio wurde bestimmt, indem der höhere Strain-Wert durch den niedrigeren dividiert wurde. Als Elastografie-Index wurde das Maximum der SP-Kurve definiert. Den Elastografie-Bildern wurde je nach Kompressionsmuster ein neuer spezifischer SP-Score zwischen 0 und 2 zugeordnet.

Ergebnisse Die Gruppe der Frühgeburten und der Normalgeburten zeigten unterschiedliche Werte für den Elastografie-Index, den SP-Score und für die Zervix-Länge (1,61 vs. 1,27, p < 0,001; SP-Score von „2“: n = 31 (62 %) vs. n = 36 (12,6 %), p < 0,001; Zervix-Länge von 30,7 vs. 41,0 mm, p < 0,001). Der Elastografie-Index und der SP-Score waren mit einer besseren Vorhersagekraft als die Zervix-Längenbestimmung allein assoziiert (AUC 0,8059 (Area under the curve); AUC 0,7716; AUC 0,7631). Die Kombination aller Parameter erwies sich als prognostisch besser als jeder einzelne Parameter für sich genommen (AUC 0,8987).

Schlussfolgerungen Ein höherer Elastografie-Index und SP-Score korrelierten mit einem erhöhten Frühgeburtsrisiko und sind der Zervix-Längenmessung als prädiktiver Marker überlegen. Eine Kombination der Parameter könnte in Form eines „Zervix-Index“ für die Vorhersage einer Frühgeburt Anwendung finden.

 
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