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BULGING OF MEMBRANES
IN CERVICAL INCOMPETENCE |
In the initial stages there may be a small amount of fluid in the cervix.
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Transvaginal scan of cervix at 18
weeks of gestation |
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Transvaginal scan at 25 weeks |
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Protrusion of the membranes through the internal cervical os is the classical appearance of cervical incompetence. Sonography can detect early membrane herniation with an intact external cervical os before changes can be detected either digitally or by speculum examination (1,2).
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Cervical incompetence – the effect of
suprapubic pressure |
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Hourglass membranes |
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Although bulging of the membranes into the cervical canal ("hourglass
membranes") is almost pathognomonic, beware of the phenomenon of pseudodilatation.
REFERENCES |
- Varma TR, Patel RH, Pillai U. Ultrasonic assessment of cervix in at risk patients. Acta Obstet Gynecol Scand 1986;65:147-152.
- Acker DB, Spitzberg EH, Benacerraf BR. Ultrasonographic diagnosis of incompetent cervix: a case report. J Reprod Med 1988;33(12):966-968.