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CLINICAL IMAGES Table of Contents  
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Funneling of internal os – Criteria for sonographic assessment of cervical incompetence

 Department of Radiology, St. John's Hospital, Bengaluru, Karnataka, India

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Date of Submission12-Mar-2022
Date of Decision04-Jun-2022
Date of Acceptance06-Jun-2022
Date of Web Publication11-Jul-2022

How to cite this URL:
Reddy R. Funneling of internal os – Criteria for sonographic assessment of cervical incompetence. Apollo Med [Epub ahead of print] [cited 2022 Sep 27]. Available from: https://apollomedicine.org/preprintarticle.asp?id=350186

  Description Top

An 18-year-old primigravida from a rural background presented to the hospital at 18 weeks of gestation with complaints of leaking per vaginum. This is the first antenatal scan for which the patient presented. She gave no history of previous spontaneous or therapeutic abortion. Further, there was no significant past surgical history. Longitudinal ultrasonography revealed funneling of the internal cervical os with open external os and bulging of fetal membranes into the cervical canal [Figure 1]. The length of the cervix is noted to be 2.5 cm. There was evidence of a single live fetus corresponding to 17 weeks 5 days. A diagnosis of cervical incompetence with funneling of internal os was made based on ultrasound features at 18 weeks gestation. The patient was referred to the department of obstetrics for further management where she underwent cervical encirclage for the management of cervical incompetence and to prevent preterm delivery. The patient was discharged home with the recommendation of timely obstetric visits during the current pregnancy.
Figure 1: Longitudinal grey scale ultrasound image demonstrating funneling of the internal cervical os (arrows) with bulging of fetal membranes into the cervical canal leading to progressive cervical dilatation with opening of external os at 18 weeks of gestation

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  Discussion Top

Open internal cervical os with protrusion of fetal amniotic membranes greater than 5 mm into the cervical canal, leading to progressive cervical dilatation is termed as “funneling of internal os.” Funneling commonly develops between 18 and 22 weeks and the significance of U-shaped or V-shaped funneling on ultrasound before 20 weeks of gestation helps predict the risk of preterm delivery in such patients.[1] Nevertheless, the entity needs to be confirmed on transvaginal ultrasound (TVS) and encirclage can be avoided when TVS is normal.[2] Funneling of the cervix is a dynamic process demonstrating slow progression from the internal os caudally to the external os and can be normal after 32 weeks of gestation.[3] Cervical encirclage is beneficial in pregnant women with short cervix length below 25 mm and/or with a previous history of spontaneous preterm delivery.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


I wish to thank Mrs. Mani Sabbavarapu for her assistance in proofreading and native English editing of the manuscript.

Conflicts of interest

There are no conflicts of interest.



  References Top

Andrews WW, Copper R, Hauth JC, Goldenberg RL, Neely C, Dubard M. Second-trimester cervical ultrasound: Associations with increased risk for recurrent early spontaneous delivery. Obstet Gynecol 2000;95:222-6.  Back to cited text no. 1
To MS, Skentou C, Liao AW, Cacho A, Nicolaides KH. Cervical length and funneling at 23 weeks of gestation in the prediction of spontaneous early preterm delivery. Ultrasound Obstet Gynecol 2001;18:200-3.  Back to cited text no. 2
Berghella V, Kuhlman K, Weiner S, Texeira L, Wapner RJ. Cervical funneling: Sonographic criteria predictive of preterm delivery. Ultrasound Obstet Gynecol 1997;10:161-6.  Back to cited text no. 3

Correspondence Address:
Ravikanth Reddy,
Department of Radiology, St. John's Hospital, Bengaluru - 560 034, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/am.am_41_22


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