MR Pelvimetry for Breech Presentation at Term– Interobserver Reliability, Incidental Findings and Reference Values

Abstract

Purpose Antepartal MR pelvimetry is used to assess the viability of vaginal breech delivery. We evaluated the reliability of MR pelvimetric measurements as well as incidental findings noted by different clinicians and assessed potential reference values.

Methods In this monocentric study, the radiologic database was searched for obstetric MR pelvimetries with singleton breech pregnancies between 1999 and 2016. 99 consecutive MR pelvimetries were included. A structured, independent review was performed by six observers with three clinical experience levels (attending, fellow, junior resident from the departments of radiology and obstetrics). Image analysis entailed the quantitative assessment of conjugata vera (CV) and diameter transversalis (DT), image quality and incidental findings. Obstetric data was retrieved from the obstetric database for reference value assessment.

Results Interobserver agreement was strong throughout (mean intraclass correlation coefficient range: 0.889 – 0.968). The individual measuring biases ranged between 0 – 2 mm, and the average limits of agreement were ± 3 mm. Regarding the mode of delivery, the recommended cesarean section (rCS) group showed significantly smaller CV measurements (CV: 11.37 ± 0.73, p-value < 0.0001) than any other delivery group. No statistical difference in CV between the vaginal delivery and unplanned cesarean section groups was found (p-value 0.902). DT measurements only showed a significant difference between rCS and elective cesarean section (p-value 0.039). 134 incidental findings were noted.

Conclusion Strong interobserver agreement irrespective of the reader’s experience level supports MR pelvimetry as a reliable method for identifying women with fetopelvic disproportion in breech presentation. For a comprehensive appraisal of incidental findings, radiologic expertise is vital.

Key points: 

• MR pelvimetry is a reliable method irrespective of the reader’s experience level.

• Conjugata vera measurements aid in the prepartal viability assessment of vaginal breech delivery.

• Incidental findings are relatively common.

Citation Format

• von Bismarck A, Ertl-Wagner B, Stöcklein S et al. MR Pelvimetry for Breech Presentation at Term– Interobserver Reliability, Incidental Findings and Reference Values. Fortschr Röntgenstr 2019; 191: 424 – 432

Zusammenfassung

Hintergrund Antepartale MR-Pelvimetrie wird genutzt, um die Durchführbarkeit von vaginalen Beckenendlagengeburten einzuschätzen. Evaluiert wurden die Reliabilität von MR-pelvimetrischen Messungen sowie Nebenbefunde durch verschiedene Kliniker; zudem wurden potenzielle Referenzwerte erwogen.

Methode In dieser monozentrischen Studie wurde die radiologische Datenbank nach MR-Pelvimetrien von Schwangeren mit Fetus in Beckenendlage zwischen 1999 und 2016 durchsucht. 99 konsekutive Pelvimetrien wurden inkludiert. Eine strukturierte, unabhängige Auswertung erfolgte durch sechs Untersucher mit drei klinischen Erfahrungsstufen (Oberarzt, Facharzt, Assistenzarzt aus je der radiologischen sowie geburtshilflichen Abteilung). Die Sequenzen wurden bezüglich der quantitativen Erfassung von Conjugata vera (CV) und Diameter transversalis (DT), Bildqualität und Nebenbefunde analysiert. Für die Untersuchung der Referenzwerte wurden geburtshilfliche Daten aus der passenden Datenbank erhoben.

Ergebnisse Die Interobserver-Übereinstimmung war durchgehend stark (Reichweite der durchschnittlichen Intraklassen-Korrelationskoeffizienten: 0,889 – 0,968). Individuelle Messfehler rangierten zwischen 0 und 2 mm, durchschnittliche Übereinstimmungsgrenzen waren ± 3 mm. In Bezug auf den Geburtsmodus wies die Gruppe „Kaiserschnitt empfohlen” (rCS) signifikant kleinere CV-Messungen auf (CV: 11,37 ± 0,73, p-Wert < 0,0001) als alle anderen Gruppen. Es wurde kein statistischer Unterschied in CV zwischen den Gruppen „vaginale Geburt” und „ungeplanter Kaiserschnitt” gefunden (p-Wert 0,902). Die DT-Messungen zeigten nur einen signifikanten Unterschied zwischen rCS und „elektiver Kaiserschnitt” (p-Wert 0,039). 134 Nebenbefunde wurden erfasst.

Schlussfolgerung Eine starke Interobserver-Übereinstimmung unabhängig von der Erfahrungsstufe des Auswerters bestätigt die MR-Pelvimetrie als eine verlässliche Methode, um ein fetopelvines Missverhältnis bei Schwangeren mit Fetus in Beckenendlage zu identifizieren. Für eine vollständige Erfassung der Nebenbefunde ist eine radiologische Expertise unabdingbar.

Kernaussagen: 

• MR-Pelvimetrie ist eine verlässliche Methode unabhängig von der Erfahrungsstufe des Auswerters.

• Conjugata-vera-Messungen helfen in präpartaler Einschätzung zur Durchführbarkeit einer vaginalen Beckenendlagengeburt.

• Zufallsbefunde kommen relativ häufig vor.

Key words

MR pelvimetry - breech - obstetric - interobserver - reference value

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