Cervical Incompetence
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DR. S. Kalaichandran, MBBS, MD, FRCSC,FSOGC (Canada), FRCOG

Lecturer University of Ottawa
Obstetrics and Gynaecology


Cervical incompetence is a major cause of fetal loss in second trimester miscarriages and preterm birth.

The incidence has increased with the increase in therapeutic abortion.


 One in 500 pregnancies is complicated by cervical incompetence.


 1. Trauma to the cervix from

 a) forceful, rapid and excessive dilatation during therapeutic abortion or as a    treatment for severe dysmenorrhoea.

 b) Delivery through an un-dilated cervix

 c) Precipitate delivery

 d) Deep cone biopsy.

2. Generalized collagen disorder with weak connective tissue.

3. Idiopathic or unknown cause.


1. Non pregnant

a) History-consider cervical incompetence during pre pregnancy counseling- previous second trimester miscarriages or preterm delivery with typically a history of pelvic pressure, watery discharge and delivery with no vaginal bleeding or pain at onset.

- consider past history of cervical trauma as described above in aetiology.

b) Easy and painless passage of Hegar 6 dilator through the internal os.

c) Funneling of cervix on a hysterogram.

2. During Pregnancy

a) History as described before

b) Ultrasound scan: Short cervix, dilated cervical canal with coning in a trans-abdominal or trans-labial sonogram.

B- Bladder,   V-Vagina,   R-Rectum,   C-Cervix

B- Bladder,   V-Fetal Head,   C-Cervix

c) Speculum or vaginal examination- cervical shortening (effacement) and dilatation of the internal os.


A patient who has had a previous second trimester loss or preterm delivery should be seen for pre-pregnancy counseling and assessment. A badly lacerated cervix can be repaired before the patient embarks on her pregnancy.

            Early ultrasound scan is necessary for dating. Subsequent scans and vaginal examination will indicate the need for a cervical suture.

            A Shirodkar suture using Merselene tape or a McDonald suture with #4 mersilk at the level of the internal os is the treatment available. This may be carried out under a spinal or a general anaesthetic.

Incompetent Cervix with
herniation of membranes
Shirodkar suture in place

Prophylactic, Therapeutic and Rescue Sutures

Prophylactic suture may be placed when there is a clear history supported by pre-pregnancy hysterogram or Hegar dilator test.  Success rate is very high in this group. However, some of the sutures may be unnecessary.

            Therapeutic sutures are placed when there is clinical or ultrasound evidence of cervical incompetence in the index pregnancy. Success rate is high and all sutures are indicated.

            Rescue sutures are those inserted as an emergency when the cervix is effaced and the internal os dilated, often with the membranes bulging into the vagina. (Hour glass appearance on sonogram). Success rate is low here with high complication rate (rupture of membrane, infection and bleeding)

            Patients with cervical suture are monitored more closely with frequent assessment of cervical length by USS and/or pelvic examination. Cervical suture is usually removed at about 37 weeks of gestation and a vaginal delivery is expected. Occasionally, a cervical suture induces fibrosis and the cervix fails to dilate in labour requiring a C. Section for delivery.



Copyright 1999 [Dr. Kalaichandran]. All rights reserved.
Revised: April 27, 2004 .