Cervical dilation

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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.

Contents

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:

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.

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.

Induced dilation in childbirth

Prostaglandins (P2 and PGE2) contribute to cervical ripening and dilation. The body produces these hormones naturally. Sometimes prostaglandins in synthesized forms are applied directly to the cervix to induce labor. [1] In women who have had a previous caesarean section, the American College of Obstetricians and Gynecologists issued a bulletin that misoprostol never be used for this purpose. ACOG's findings conclude that the collagen softening properties of misoprostol could be absorbed through the cervix and vaginal vault up into the low transverse scar of a typical caesarean section, and significantly increase the risk of uterine rupture. [2] [ 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 nipple stimulation, which produces oxytocin, a hormone which is necessary for uterine contractions. Nipple stimulation can be performed manually, by use of a breast pump, or by suckling. Henci Goer, in her comprehensive book, The Thinking Woman's Guide to a Better Birth, details how this practice was researched in two separate studies of 100 and 200 women in the mid nineteen-eighties. Women were assigned randomly to two groups. In one group, nipples were stimulated for one-hour sessions, three times per day. In the other group, women were to avoid any form of nipple stimulation or sexual intercourse. The researchers concluded in both studies that nipple stimulation could indeed ripen the cervix and in some cases induce 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 balloon catheter may be used. Other products include osmotic dilators, such as laminaria stick (made of dried seaweed) or synthetic hygroscopic materials, which expand when placed in a moist environment. [1]

Results from 2021 systematic reviews of the literature found no differences in caesarean delivery, neonatal, nor maternal outcomes between inpatient or outpatient cervical ripening. [5] [6]

In abortion care

In treatment of spontaneous or 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]

Related Research Articles

<span class="mw-page-title-main">Cervix</span> Lower part of the uterus in the female reproductive system

The cervix or cervix uteri is a dynamic fibromuscular sexual organ of the female reproductive system that connects the vagina with the uterine cavity. The human female cervix has been documented anatomically since at least the time of Hippocrates, over 2,000 years ago. The cervix is approximately 4 cm long with a diameter of approximately 3 cm and tends to be described as a cylindrical shape, although the front and back walls of the cervix are contiguous. The size of the cervix changes throughout a woman's life cycle. For example, during the fertile years of a woman's reproductive cycle, females tend to have a larger cervix vis á vis postmenopausal females; likewise, females who have produced offspring have a larger sized cervix than females who have not produced offspring.

Dilationand curettage (D&C) refers to the dilation of the cervix and surgical removal of sections and/or layers of the lining of the uterus and or contents of the uterus such as an unwanted fetus, remains of a non-viable fetus, retained placenta after birth or abortion as well as any abnormal tissue which may be in the uterus causing abnormal cycles by scraping and scooping (curettage). It is a gynecologic procedure used for treatment and removal as well as diagnostic and therapeutic purposes, and is the most commonly used method for first trimester abortion or miscarriage.

<span class="mw-page-title-main">Misoprostol</span> Medication to induce abortion and treat ulcers

Misoprostol is a synthetic prostaglandin medication used to prevent and treat stomach and duodenal ulcers, induce labor, cause an abortion, and treat postpartum bleeding due to poor contraction of the uterus. It is taken by mouth when used to prevent gastric ulcers in people taking nonsteroidal anti-inflammatory drugs (NSAID). For abortions it is used by itself or in conjunction with mifepristone or methotrexate. By itself, effectiveness for abortion is between 66% and 90%. For labor induction or abortion, it is taken by mouth, dissolved in the mouth, or placed in the vagina. For postpartum bleeding it may also be used rectally.

Uterine contractions are muscle contractions of the uterine smooth muscle that can occur at various intensities in both the non-pregnant and pregnant uterine state. The non-pregnant uterus undergoes small, spontaneous contractions in addition to stronger, coordinated contractions during the menstrual cycle and orgasm. Throughout gestation, the uterus enters a state of uterine quiescence due to various neural and hormonal changes. During this state, the uterus undergoes little to no contractions, though spontaneous contractions still occur for the uterine myocyte cells to experience hypertrophy. The pregnant uterus only contracts strongly during orgasms, labour, and in the postpartum stage to return to its natural size.

Labor induction is the process or treatment that stimulates childbirth and delivery. Inducing (starting) labor can be accomplished with pharmaceutical or non-pharmaceutical methods. In Western countries, it is estimated that one-quarter of pregnant women have their labor medically induced with drug treatment. Inductions are most often performed either with prostaglandin drug treatment alone, or with a combination of prostaglandin and intravenous oxytocin treatment.

Rupture of membranes (ROM) or amniorrhexis is a term used during pregnancy to describe a rupture of the amniotic sac. Normally, it occurs spontaneously at full term either during or at the beginning of labor. Rupture of the membranes is known colloquially as "breaking (one's) water," especially when induced rather than spontaneous, or as one's "water breaking". A premature rupture of membranes (PROM) is a rupture of the amnion that occurs at full term and prior to the onset of labor. In cases of PROM, options include expectant management without intervention, or interventions such as oxytocin or other methods of labor induction, and both are usually accompanied by close monitoring of maternal and fetal health. Preterm premature rupture of membranes (PPROM) is when water breaks both before the onset of labor and before the pregnancy's 37 week gestation. In the United States, more than 120,000 pregnancies per year are affected by a premature rupture of membranes, which is the cause of about one third of preterm deliveries.

<span class="mw-page-title-main">Asherman's syndrome</span> Medical condition

Asherman's syndrome (AS) is an acquired uterine condition that occurs when scar tissue (adhesions) forms inside the uterus and/or the cervix. It is characterized by variable scarring inside the uterine cavity, where in many cases the front and back walls of the uterus stick to one another. AS can be the cause of menstrual disturbances, infertility, and placental abnormalities. Although the first case of intrauterine adhesion was published in 1894 by Heinrich Fritsch, it was only after 54 years that a full description of Asherman syndrome was carried out by Joseph Asherman. A number of other terms have been used to describe the condition and related conditions including: uterine/cervical atresia, traumatic uterine atrophy, sclerotic endometrium, and endometrial sclerosis.

Bloody show or show is the passage of a small amount of blood or blood-tinged mucus through the vagina near the end of pregnancy. It is caused by thinning and dilation of the cervix, leading to detachment of the cervical mucus plug that seals the cervix during pregnancy and tearing of small cervical blood vessels, and is one of the signs that labor may be imminent. The bloody show may be expelled from the vagina in pieces or altogether and often appears as a jelly-like piece of mucus stained with blood. Although the bloody show may be alarming at first, it is not a concern of patient health after 37 weeks gestation.

<span class="mw-page-title-main">Vacuum aspiration</span> Gynaecological procedure

Vacuum or suction aspiration is a procedure that uses a vacuum source to remove an embryo or fetus through the cervix. The procedure is performed to induce abortion, as a treatment for incomplete spontaneous abortion or retained fetal and placental tissue, or to obtain a sample of uterine lining. It is generally safe, and serious complications rarely occur.

Dilation and evacuation (D&E) or dilatation and evacuation is the dilation of the cervix and surgical evacuation of the uterus after the first trimester of pregnancy. It is a method of abortion as well as a common procedure used after miscarriage to remove all pregnancy tissue.

<span class="mw-page-title-main">Cervical effacement</span> Thinning and shortening of the cervix

Cervical effacement or cervical ripening refers to the thinning and shortening of the cervix. This process occurs during labor to prepare the cervix for dilation to allow the fetus to pass through the vagina. While this is a normal, physiological process that occurs at the later end of pregnancy, it can also be induced through medications and procedures.

Cervical weakness, also called cervical incompetence or cervical insufficiency, is a medical condition of pregnancy in which the cervix begins to dilate (widen) and efface (thin) before the pregnancy has reached term. Definitions of cervical weakness vary, but one that is frequently used is the inability of the uterine cervix to retain a pregnancy in the absence of the signs and symptoms of clinical contractions, or labor, or both in the second trimester. Cervical weakness may cause miscarriage or preterm birth during the second and third trimesters. It has been estimated that cervical insufficiency complicates about 1% of pregnancies, and that it is a cause in about 8% of women with second trimester recurrent miscarriages.

Prostaglandin E<sub>2</sub> Chemical compound

Prostaglandin E2 (PGE2), also known as dinoprostone, is a naturally occurring prostaglandin with oxytocic properties that is used as a medication. Dinoprostone is used in labor induction, bleeding after delivery, termination of pregnancy, and in newborn babies to keep the ductus arteriosus open. In babies it is used in those with congenital heart defects until surgery can be carried out. It is also used to manage gestational trophoblastic disease. It may be used within the vagina or by injection into a vein.

<span class="mw-page-title-main">Uterine atony</span> Loss of tone in the uterine musculature

Uterine atony is the failure of the uterus to contract adequately following delivery. Contraction of the uterine muscles during labor compresses the blood vessels and slows flow, which helps prevent hemorrhage and facilitates coagulation. Therefore, a lack of uterine muscle contraction can lead to an acute hemorrhage, as the vasculature is not being sufficiently compressed. Uterine atony is the most common cause of postpartum hemorrhage, which is an emergency and potential cause of fatality. Across the globe, postpartum hemorrhage is among the top five causes of maternal death. Recognition of the warning signs of uterine atony in the setting of extensive postpartum bleeding should initiate interventions aimed at regaining stable uterine contraction.

<span class="mw-page-title-main">Osmotic dilator</span> Medical device to dilate the uterine cervix

Osmotic dilators, also known as hygroscopic dilators, are medical implements used to dilate the uterine cervix by swelling as they absorb fluid from surrounding tissue. They may be composed of natural or synthetic materials. A laminaria stick or tent is a thin rod made of the stems of dried Laminaria, a genus of kelp. Laminaria sticks can be generated from Laminaria japonica and Laminaria digitata. Synthetic osmotic dilators are commonly referred to by their brand names, such as Dilapan. Dilapan-S are composed of polyacrylonitrile, a plastic polymer. The hygroscopic nature of the polymer causes the dilator to absorb fluid and expand.

A cervical mucus plug (operculum) is a plug that fills and seals the cervical canal during pregnancy. It is formed by a small amount of cervical mucus that condenses to form a cervical mucus plug during pregnancy.

A uterotonic, also known as an oxytocic or ecbolic, is a type of medication used to induce contraction or greater tonicity of the uterus. Uterotonics are used both to induce labor and to reduce postpartum hemorrhage.

Uterine Tachysystole is a condition of excessively frequent uterine contractions during pregnancy. It is most often seen in induced or augmented labor, though it can also occur during spontaneous labor, and this may result in fetal hypoxia and acidosis. This may have serious effects on both the mother and the fetus including hemorrhaging and death. There are still major gaps in understanding treatment as well as clinical outcomes of this condition. Uterine tachysystole is defined as more than 5 contractions in 10 minutes, averaged over a 30-minute period.

<span class="mw-page-title-main">Hysterosalpingography</span> X-ray examination of the uterus and fallopian tubes

Hysterosalpingography (HSG), also known as uterosalpingography, is a radiologic procedure to investigate the shape of the uterine cavity and the shape and patency of the fallopian tubes. It is a special x-ray procedure using dye to look at the womb (uterus) and fallopian tubes. In this procedure, a radio-opaque material is injected into the cervical canal, and radiographs are taken. A normal result shows the filling of the uterine cavity and the bilateral filling of the fallopian tube with the injection material. To demonstrate tubal patency, spillage of the material into the peritoneal cavity needs to be observed. Hysterosalpingography has vital role in treatment of infertility, especially in the case of fallopian tube blockage.

<span class="mw-page-title-main">Prolonged labor</span> Medical condition

Prolonged labor is the inability of a woman to proceed with childbirth upon going into labor. Prolonged labor typically lasts over 20 hours for first time mothers, and over 14 hours for women that have already had children. Failure to progress can take place during two different phases; the latent phase and active phase of labor. The latent phase of labor can be emotionally tiring and cause fatigue, but it typically does not result in further problems. The active phase of labor, on the other hand, if prolonged, can result in long term complications.

References

  1. 1 2 Rai, Jodie; James R. Schreiber (5 December 2007). "Cervical Ripening". EMedicine.com. WebMD. Retrieved 2008-05-04.
  2. ↑ American College of Obstetricians and Gynecologists Committee on Obstetric Practice (August 2006). "ACOG Committee Opinion No. 342: induction of labor for vaginal birth after cesarean delivery". Obstet Gynecol. 108 (2): 465–8. doi: 10.1097/00006250-200608000-00045 . PMID   16880321.
  3. ↑ Tenore JL (May 2003). "Methods for cervical ripening and induction of labor". Am Fam Physician. 67 (10): 2123–8. PMID   12776961. Archived from the original on 2008-05-16. Retrieved 2008-05-04.
  4. ↑ The Thinking Woman's Guide to a Better Birth by Henci Goer,1999, ISBN   0-399-52517-3
  5. ↑ McDonagh, Marian; Skelly, Andrea C.; Tilden, Ellen; Brodt, Erika D.; Dana, Tracy; Hart, Erica; Kantner, Shelby N.; Fu, Rongwei; Hermesch, Amy C. (2021). "Outpatient Cervical Ripening: A Systematic Review and Meta-analysis". Obstetrics & Gynecology. 137 (6): 1091–1101. doi:10.1097/AOG.0000000000004382. ISSN   0029-7844. PMC   8011513 . PMID   33752219.
  6. ↑ McDonagh, Marian; Skelly, Andrea C.; Hermesch, Amy; Tilden, Ellen; Brodt, Erika D.; Dana, Tracy; Ramirez, Shaun; Fu, Rochelle; Kantner, Shelby N. (2021). Cervical Ripening in the Outpatient Setting. AHRQ Comparative Effectiveness Reviews. Rockville (MD): Agency for Healthcare Research and Quality (US). PMID   33818996.
  7. 1 2 3 4 Kapp, Nathalie; Lohr, Patricia A; Ngo, Thoai D; Hayes, Jennifer L (2010-02-17). "Cervical preparation for first trimester surgical abortion". Cochrane Database of Systematic Reviews (2): CD007207. doi:10.1002/14651858.cd007207.pub2. ISSN   1465-1858. PMID   20166091.
  8. ↑ "Overview | Abortion care | Guidance | NICE". www.nice.org.uk. 25 September 2019. Retrieved 2020-07-21.
  9. 1 2 3 Newmann, Sara J; Dalve-Endres, Andrea; Diedrich, Justin T.; Steinauer, Jody E; Meckstroth, Karen; Drey, Eleanor A. (2010-08-04). "Cervical preparation for second trimester dilation and evacuation". Cochrane Database of Systematic Reviews (8): CD007310. doi:10.1002/14651858.cd007310.pub2. ISSN   1465-1858. PMID   20687085.
  10. ↑ Laparoscopy and Hysteroscopy. Archived 2020-07-26 at the Wayback Machine A Guide for Patients, Revised 2012. From the American Society for Reproductive Medicine, Patient Education Committee
  11. ↑ Polyzos, N. P.; Zavos, A.; Valachis, A.; Dragamestianos, C.; Blockeel, C.; Stoop, D.; Papanikolaou, E. G.; Tournaye, H.; Devroey, P.; Messinis, I. E. (2012). "Misoprostol prior to hysteroscopy in premenopausal and post-menopausal women. A systematic review and meta-analysis". Human Reproduction Update. 18 (4): 393–404. doi: 10.1093/humupd/dms014 . PMID   22544173.
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