Cervical dilation
From Wikipedia, the free encyclopedia
Cervical dilation 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 by medical means.
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[edit] Labor
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:[1]
- 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.)
[edit] 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 mucous 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.
Bloody show is another indication that the cervix is dilating. Bloody show usually comes along with the mucus plug, and may continue throughout labor, making the mucus tinged pink, red or brown. Fresh, red blood is usually not associated with dilation, but rather serious complications such as placental abruption, or 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.
[edit] Induced dilation
Prostaglandins contribute to cervical ripening and dilation. The body produces these naturally. Sometimes prostaglandins in synthesized forms are applied directly to the cervix to induce labor.[2] In women who have had a previous cesarean sections, the American College of Obstetricians and Gynecologists recommends that misoprostol not be used for this purpose.[3] 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.[4]
Cervical dilation may be induced mechanically by placing devices inside the cervix that will expand while in place. A balloon catheter may be used. Other products include laminaria (made of dried seaweed) or synthetic hygroscopic products, which expand when placed in a moist environment.[2]
[edit] References
- ^ Rodriguez, Lisa; Marjorie Greenfield (14 August 2004). Examination during Labor. DrSpock.com. Retrieved on 2008-05-04.
- ^ a b Rai, Jodie; James R. Schreiber (5 December 2007). "Cervical Ripening". eMedicine.com. WebMD.
- ^ "ACOG Committee Opinion No. 342: induction of labor for vaginal birth after cesarean delivery" (August 2006). Obstet Gynecol 108 (2): 465–8. PMID 16880321.
- ^ Tenore JL (May 2003). "Methods for cervical ripening and induction of labor". Am Fam Physician 67 (10): 2123–8. PMID 12776961.
[edit] External links
- Animation of cervical dilation during childbirth from the University of Pennsylvania Medical Animation Library
