Cervical dilation

Source: Wikipedia, the free encyclopedia.

Cervical dilation (or cervical dilatation) is the opening of the cervix, the entrance to the uterus, during childbirth, miscarriage, induced abortion, or gynecological surgery. Cervical dilation may occur naturally, or may be induced surgically or medically.

In childbirth

In the later stages of pregnancy, the cervix may already have opened up to 1–3 cm (or more in rarer circumstances), but during labor, repeated uterine contractions lead to further widening of the cervix to about 6 centimeters. From that point, pressure from the presenting part (head in vertex births or bottom in breech births), along with uterine contractions, will dilate the cervix to 10 centimeters, which is "complete." Cervical dilation is accompanied by effacement, the thinning of the cervix.

General guidelines for cervical dilation:

  • Latent phase: 0–3 centimeters
  • Active Labor: 4–7 centimeters
  • Transition: 8–10 centimeters
  • Complete: 10 centimeters. Delivery of the infant takes place shortly after this stage is reached (although the mother does not always push right away.)

Symptoms

During pregnancy, the os (opening) of the cervix is blocked by a thick plug of mucus to prevent bacteria from entering the uterus. During dilation, this plug is loosened. It may come out as one piece, or as thick mucus discharge from the vagina. When this occurs, it is an indication that the cervix is beginning to dilate, although not all women will notice this mucus plug being released.

placenta previa
. Red blood in small quantities often also follows an exam.

The pain experienced during dilation is similar to that of menstruation (although markedly more intense), as period pains are thought to be due to the passing of endometrium through the cervix. Most of the pain during labor is caused by the uterus contracting to dilate the cervix.

Induced dilation in childbirth

obsolete source] Prostaglandins are also present in human semen, and sexual intercourse is commonly recommended for promoting the onset of labor, although the limited data available makes the effectiveness of this method uncertain.[3]

Other means of natural cervical ripening include

uterine contractions. Goer further notes that in the smaller study, an external fetal monitor was used, and no uterine hyperstimulation was noted.[4][unreliable source
]

Cervical dilation may be induced mechanically by placing devices inside the cervix that will expand while in place. A

hygroscopic materials, which expand when placed in a moist environment.[1]

Results from 2021 systematic reviews of the literature found no differences in

cervical ripening.[5][6]

In abortion care

In treatment of

induced abortion, preparation (softening and dilating) of the cervix allows the cannulae vacuum aspiration to pass more easily into the uterus, which may make the procedure shorter in duration, more comfortable for the patient, and easier to perform.[7][8] Preparation may also reduce the rare complications of uterine perforation and cervical injury.[7][9] Options for cervical preparation prior to the abortion procedure include osmotic dilators and pharmacologic agents. Osmotic dilators produce wide cervical dilation in a predictable fashion and are generally used in more advanced pregnancies.[7][9] Pharmacologic agents, such as misoprostol and mifepristone, soften the cervix and facilitate cervical dilation, and may be used alone in early pregnancy, or in combination with osmotic dilators prior to dilation and evacuation.[7][9]

In hysteroscopy

In hysteroscopy, the diameter of the hysteroscope is generally too large to conveniently pass the cervix directly, thereby necessitating cervical dilation to be performed prior to insertion. Cervical dilation can be performed by temporarily stretching the cervix with a series of (cervical) dilators of increasing diameter.[10] Misoprostol prior to hysteroscopy for cervical dilation appears to facilitate an easier and uncomplicated procedure only in premenopausal women.[11]

References

  1. ^ a b Rai, Jodie; James R. Schreiber (5 December 2007). "Cervical Ripening". EMedicine.com. WebMD. Retrieved 2008-05-04.
  2. PMID 16880321. [dead link
    ]
  3. PMID 12776961. Archived from the original
    on 2008-05-16. Retrieved 2008-05-04.
  4. ISBN 0-399-52517-3
  5. PMID 33752219
    .
  6. PMID 33818996
    .
  7. ^
    PMID 20166091
    .
  8. ^ "Overview | Abortion care | Guidance | NICE". www.nice.org.uk. 25 September 2019. Retrieved 2020-07-21.
  9. ^
    PMID 20687085
    .
  10. ^ Laparoscopy and Hysteroscopy. A Guide for Patients, Revised 2012. From the American Society for Reproductive Medicine, Patient Education Committee
  11. PMID 22544173
    .
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