Cervical cap
Encyclopedia
The cervical cap is a form of barrier contraception
. A cervical cap fits over the cervix
and blocks sperm
from entering the uterus
through the external orifice of the uterus
, called the os.
The Lea's Shield was a cervical barrier device which was discontinued as of 2008. Some sources use cervical cap to refer to the FemCap and Lea's Shield. Other sources include FemCap in the term cervical cap, but classified the Lea's Shield as a distinct device.
Cervical caps or conception caps have also been designed as a form of assisted reproductive technology
, used to help people experiencing infertility.
is thousands of years old. Various cultures have used cervix-shaped devices such as oiled paper
cones or lemon
halves. Others made sticky mixtures that included honey
or cedar rosin
, to be applied to the os. The modern idea of a cervical cap as a fitted device that seals itself against the vagina
l walls is of more recent origin; it emerged within the past century.
molds of the cervix for some of his patients. These caps were probably short-lived, as uncured rubber degrades fairly quickly. An important precursor to the invention of more lasting caps was the rubber vulcanization
process, patented by Charles Goodyear
in 1844. An occlusive pessary
marketed in the United States as the "womb veil
" seems to have been an early form of diaphragm
or cervical cap.
Over the next several decades, the cervical cap became the most widely used barrier contraceptive method in Western Europe
and Britain. Although the diaphragm was always more popular in the United States than the cervical cap, the cap was also common.
.
Use of all barrier methods, but especially cervical barriers, dropped dramatically after the 1960s introduction of the combined oral contraceptive pill and the intrauterine device. In 1976, the U.S. government enacted the Medical Device Amendment. This law required all manufacturers of medical device
s to provide the United States Food and Drug Administration (FDA) with data on the safety and efficacy of those devices. Lamberts (Dalston) Ltd., the only manufacturer at that time, failed to provide this information, and the FDA banned the use of cervical caps in the United States.
In the late 1970s, the FDA reclassified the cervical cap as an investigational device, and it regained limited availability. Within a few years, the FDA withdrew investigational status from the Vimule cap, following a study that associated its use with vaginal lacerations. In 1988, the Prentif cap gained FDA approval. The feminist movement
played a large role in re-introducing the cervical cap to the United States. One paper called its involvement at all steps of the FDA approval process "unprecedented."
The cavity rim caps are Prentif, made of latex, and the disposable cap Oves, made of silicone. There are four sizes of Prentif: 22, 25, 28, and 31 mm. There are three sizes of Oves: 26, 28, and 30 mm. Unique among cervical caps, it adheres to the cervix by surface tension
, rather than by suction.
The other devices are the latex Dumas and Vimule, and the silicone FemCap, Lea's Shield, and Shanghai Lily. There are five sizes of Dumas: 50, 55, 60, 65, and 75 mm. There are three sizes of Vimule: 42, 48, and 52 mm. There are three sizes of FemCap: 22, 26, and 30 mm. There are four sizes of Shanghai Lily: 54, 58, 62, and 66 mm. Lea's Shield is manufactured in a single size. Unlike the other caps, Lea's Shield has a one-way air valve that helps it seal to the vaginal walls. The valve also allows the passage of cervical mucus. FemCap does not have such a valve and as such can be used to collect cervical mucus to support the billings method. Both Lea's Shield and FemCap have loops to assist in removal.
Shanghai Lily is only available in China
. As of 2008, many of the other devices are no longer being manufactured: Prentif, Vimule, and Dumas have been discontinued. Oves is only being sold as a conception cap, not as a birth control device. As of February 2009, FemCap was the only brand of cervical cap available in the United States. FemCap is also available in the UK via the NHS on prescription and is often distributed free from Family Planning Clinics depending on the health authority.
Lea's Shield is only available as the German brand LEA contraceptivum.
Individuals who wish to use a cervical cap are screened by a health care provider
to determine if a cervical cap, or one brand of cap, is appropriate for them. If a cap is determined to be appropriate, the provider will determine the proper size. The user must be refitted after any duration of pregnancy, whether the pregnancy is aborted
, miscarried
, or carried to term through vaginal childbirth
or caesarean section
.
Several factors may make a cap inappropriate for a particular woman. Women who have given birth may have scar tissue or irregularly shaped cervix
es that interfere with the cap forming a good seal. For some women, available sizes of cervical caps do not provide a correct fit. Also, cavity rim caps are not recommended for women with an anteflexed uterus.
Obtaining a fitting appointment may be difficult for some women. A 1997 survey in the United States found that most family medicine residents had no experience with prescription methods of birth control other than oral contraceptives. In some countries, some devices (such as the Lea's Shield) are available without a prescription
.
into the vaginal canal. The cap is inserted prior to sexual intercourse
; some sources state that insertion prior to sexual arousal
decreases the risk of incorrect placement. Most sources recommend the use of spermicide
with the cap, but some sources say spermicide use is optional.
The cap remains in the vagina for a minimum of 6 or 8 hours after the last intravaginal ejaculation
. It is recommended the cap be removed within 72 hours (within 48 hours recommended in the U.S.) Other than the disposable Oves cap, after use cervical caps are washed and stored for reuse. Silicone devices may be boiled to sterilize them. Reusable caps may last for one or two years.
, can be assessed two ways: method effectiveness and actual effectiveness. The method effectiveness is the proportion of couples correctly and consistently using the method who do not become pregnant. Actual effectiveness is the proportion of couples who intended that method as their sole form of birth control and do not become pregnant; it includes couples who sometimes use the method incorrectly, or sometimes not at all. Rates are generally presented for the first year of use. Most commonly the Pearl Index
is used to calculate effectiveness rates, but some studies use decrement table
s.
Contraceptive Technology reports that the method failure rate of the Prentif cervical cap with spermicide is 9% per year for nulliparous
women (women who have never given birth), and 26% per year for parous women. The actual pregnancy rates among Prentif users vary depending on the population being studied, with yearly rates of 11% to 32% being reported.
Little data is available on the effectiveness of the Oves cap and Femcap. The Oves manufacturer cites one small study of 17 users. The Femcap website does not cite any data on the current version of the Femcap; but lists data for an older version which is no longer approved by the FDA.
The only effectiveness trial of Lea's Shield was too small to determine method effectiveness. The actual pregnancy rate was 15% per year. Of the women in the trial, 85% were parous
(had given birth). The study authors estimate that for nulliparous women (those who have never given birth) the pregnancy rate in typical use may be lower, around 5% per year.
and discomfort among female users and their male sex partners, and that the modifications decreased acceptability of the device compared with the earlier version. The study of the Oves cap reported that few women indicated that they would use the cap in the future.
A pilot study conducted in Britain prior to the Lea's Shield's approval concluded that the Lea's Shield "may be acceptable to a highly select minority of women".
As of 2002, the cervical cap was one of the least common methods of contraception
in the United States. A 2002 study indicated that of sexually active American women, 0.6% are currently using either the cervical cap, contraceptive sponge
, or female condom
as their primary method of contraception, and fewer than 1% have ever used a cervical cap.
Barrier contraception
Barrier contraception methods prevent pregnancy by physically preventing sperm from entering the uterus.-History:The earliest recorded barrier methods are those of stem pessaries, found in Egypt. The diaphragm and reusable condoms became common after the invention of rubber vulcanization in the...
. A cervical cap fits over the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
and blocks sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
from entering the uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
through the external orifice of the uterus
External orifice of the uterus
The external orifice of the uterus is a small, depressed, somewhat circular aperture on the rounded extremity of the vaginal portion of the cervix. Through this aperture, the cervical cavity communicates with that of the vagina.The external orifice is bounded by two lips, an anterior and a posterior...
, called the os.
Terminology
The term cervical cap has been used to refer to a number of barrier contraceptives, including the Prentif, Dumas, Vimule, and Oves devices. In the United States, Prentif was the only brand available for several decades (Prentif was withdrawn from the U.S. market in 2005). During this time, it was common to use the term cervical cap to refer exclusively to the Prentif brand.The Lea's Shield was a cervical barrier device which was discontinued as of 2008. Some sources use cervical cap to refer to the FemCap and Lea's Shield. Other sources include FemCap in the term cervical cap, but classified the Lea's Shield as a distinct device.
Cervical caps or conception caps have also been designed as a form of assisted reproductive technology
Assisted reproductive technology
Assisted reproductive technology is a general term referring to methods used to achieve pregnancy by artificial or partially artificial means. It is reproductive technology used primarily in infertility treatments. Some forms of ART are also used in fertile couples for genetic reasons...
, used to help people experiencing infertility.
Ancient
The idea of blocking the cervix to prevent pregnancyPregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
is thousands of years old. Various cultures have used cervix-shaped devices such as oiled paper
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
cones or lemon
Lemon
The lemon is both a small evergreen tree native to Asia, and the tree's ellipsoidal yellow fruit. The fruit is used for culinary and non-culinary purposes throughout the world – primarily for its juice, though the pulp and rind are also used, mainly in cooking and baking...
halves. Others made sticky mixtures that included honey
Honey
Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...
or cedar rosin
Rosin
.Rosin, also called colophony or Greek pitch , is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black...
, to be applied to the os. The modern idea of a cervical cap as a fitted device that seals itself against the vagina
Vagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
l walls is of more recent origin; it emerged within the past century.
19th century
In 1838, German gynecologist Friedrich Wilde created the first modern cervical cap by making custom-made rubberRubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
molds of the cervix for some of his patients. These caps were probably short-lived, as uncured rubber degrades fairly quickly. An important precursor to the invention of more lasting caps was the rubber vulcanization
Vulcanization
Vulcanization or vulcanisation is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent "curatives." These additives modify the polymer by forming crosslinks between individual polymer chains. Vulcanized material is...
process, patented by Charles Goodyear
Charles Goodyear
Charles Goodyear was an American inventor who developed a process to vulcanize rubber in 1839 -- a method that he perfected while living and working in Springfield, Massachusetts in 1844, and for which he received patent number 3633 from the United States Patent Office on June 15, 1844Although...
in 1844. An occlusive pessary
Pessary
A pessary is a small plastic or silicone medical device which is inserted into the vagina or rectum and held in place by the pelvic floor musculature. - Therapeutic pessaries :...
marketed in the United States as the "womb veil
Womb veil
The womb veil was a 19th-century American form of barrier contraception consisting of an occlusive pessary made of rubber. It was a forerunner to the modern diaphragm and cervical cap. The name was first used by Edward Bliss Foote in 1863 for the device he designed and marketed...
" seems to have been an early form of diaphragm
Diaphragm (contraceptive)
The diaphragm is a cervical barrier type of birth control. It is a soft latex or silicone dome with a spring molded into the rim. The spring creates a seal against the walls of the vagina.-Use:...
or cervical cap.
Over the next several decades, the cervical cap became the most widely used barrier contraceptive method in Western Europe
Western Europe
Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...
and Britain. Although the diaphragm was always more popular in the United States than the cervical cap, the cap was also common.
20th century
Many designs were developed in the later 19th and early 20th century. The Vimule cap became available as early as 1927. A book by Vimule and Co., published in 1898, advertises the Vimule Cap. The Prentif brand cap was introduced in the early 1930s. The Dumas cap was initially made of plastic, and was available by the 1940s. Lamberts (Dalston) Ltd. of the UK manufactured these three cap types. Other types of caps had stems to hold them in place in the cervix; some of the stems actually extended into the uterus. These stem pessaries became precursors to the modern intrauterine deviceIntrauterine device
A copper IUD is a type of intrauterine device. Most IUDs have a plastic T- or U-shaped frame which is wrapped in copper wire, with the exception of Gynefix, which is a plastic string with several copper beads, affixed to the fundus of the uterus...
.
Use of all barrier methods, but especially cervical barriers, dropped dramatically after the 1960s introduction of the combined oral contraceptive pill and the intrauterine device. In 1976, the U.S. government enacted the Medical Device Amendment. This law required all manufacturers of medical device
Medical device
A medical device is a product which is used for medical purposes in patients, in diagnosis, therapy or surgery . Whereas medicinal products achieve their principal action by pharmacological, metabolic or immunological means. Medical devices act by other means like physical, mechanical, thermal,...
s to provide the United States Food and Drug Administration (FDA) with data on the safety and efficacy of those devices. Lamberts (Dalston) Ltd., the only manufacturer at that time, failed to provide this information, and the FDA banned the use of cervical caps in the United States.
In the late 1970s, the FDA reclassified the cervical cap as an investigational device, and it regained limited availability. Within a few years, the FDA withdrew investigational status from the Vimule cap, following a study that associated its use with vaginal lacerations. In 1988, the Prentif cap gained FDA approval. The feminist movement
Feminist movement
The feminist movement refers to a series of campaigns for reforms on issues such as reproductive rights, domestic violence, maternity leave, equal pay, women's suffrage, sexual harassment and sexual violence...
played a large role in re-introducing the cervical cap to the United States. One paper called its involvement at all steps of the FDA approval process "unprecedented."
Types
Several brands of caps were manufactured during the late 20th and early 21st centuries. They can be divided into two types: cavity rim caps, and other caps. Cavity rim caps adhere to the cervix, while other caps adhere to the vaginal walls around the cervix.The cavity rim caps are Prentif, made of latex, and the disposable cap Oves, made of silicone. There are four sizes of Prentif: 22, 25, 28, and 31 mm. There are three sizes of Oves: 26, 28, and 30 mm. Unique among cervical caps, it adheres to the cervix by surface tension
Surface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
, rather than by suction.
The other devices are the latex Dumas and Vimule, and the silicone FemCap, Lea's Shield, and Shanghai Lily. There are five sizes of Dumas: 50, 55, 60, 65, and 75 mm. There are three sizes of Vimule: 42, 48, and 52 mm. There are three sizes of FemCap: 22, 26, and 30 mm. There are four sizes of Shanghai Lily: 54, 58, 62, and 66 mm. Lea's Shield is manufactured in a single size. Unlike the other caps, Lea's Shield has a one-way air valve that helps it seal to the vaginal walls. The valve also allows the passage of cervical mucus. FemCap does not have such a valve and as such can be used to collect cervical mucus to support the billings method. Both Lea's Shield and FemCap have loops to assist in removal.
Shanghai Lily is only available in China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. As of 2008, many of the other devices are no longer being manufactured: Prentif, Vimule, and Dumas have been discontinued. Oves is only being sold as a conception cap, not as a birth control device. As of February 2009, FemCap was the only brand of cervical cap available in the United States. FemCap is also available in the UK via the NHS on prescription and is often distributed free from Family Planning Clinics depending on the health authority.
Lea's Shield is only available as the German brand LEA contraceptivum.
Fitting
Health care provider
A health care provider is an individual or an institution that provides preventive, curative, promotional or rehabilitative health care services in a systematic way to individuals, families or communities....
to determine if a cervical cap, or one brand of cap, is appropriate for them. If a cap is determined to be appropriate, the provider will determine the proper size. The user must be refitted after any duration of pregnancy, whether the pregnancy is aborted
Abortion
Abortion is defined as the termination of pregnancy by the removal or expulsion from the uterus of a fetus or embryo prior to viability. An abortion can occur spontaneously, in which case it is usually called a miscarriage, or it can be purposely induced...
, miscarried
Miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...
, or carried to term through vaginal childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
or caesarean section
Caesarean section
A Caesarean section, is a surgical procedure in which one or more incisions are made through a mother's abdomen and uterus to deliver one or more babies, or, rarely, to remove a dead fetus...
.
Several factors may make a cap inappropriate for a particular woman. Women who have given birth may have scar tissue or irregularly shaped cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
es that interfere with the cap forming a good seal. For some women, available sizes of cervical caps do not provide a correct fit. Also, cavity rim caps are not recommended for women with an anteflexed uterus.
Obtaining a fitting appointment may be difficult for some women. A 1997 survey in the United States found that most family medicine residents had no experience with prescription methods of birth control other than oral contraceptives. In some countries, some devices (such as the Lea's Shield) are available without a prescription
Over-the-counter drug
Over-the-counter drugs are medicines that may be sold directly to a consumer without a prescription from a healthcare professional, as compared to prescription drugs, which may be sold only to consumers possessing a valid prescription...
.
Use
The first step in inserting or removing a cervical cap is handwashing, to avoid introducing harmful bacteriaBacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
into the vaginal canal. The cap is inserted prior to sexual intercourse
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...
; some sources state that insertion prior to sexual arousal
Sexual arousal
Sexual arousal, or sexual excitement, is the arousal of sexual desire, during or in anticipation of sexual activity. Things that precipitate human sexual arousal are called erotic stimuli, or colloquially known as turn-ons. There are many potential stimuli, both physical or mental, which can cause...
decreases the risk of incorrect placement. Most sources recommend the use of spermicide
Spermicide
Spermicide is a contraceptive substance that eradicates sperm, inserted vaginally prior to intercourse to prevent pregnancy. As a contraceptive, spermicide may be used alone. However, the pregnancy rate experienced by couples using only spermicide is higher than that of couples using other methods...
with the cap, but some sources say spermicide use is optional.
The cap remains in the vagina for a minimum of 6 or 8 hours after the last intravaginal ejaculation
Ejaculation
Ejaculation is the ejecting of semen from the male reproductory tract, and is usually accompanied by orgasm. It is usually the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases ejaculation occurs because of prostatic disease...
. It is recommended the cap be removed within 72 hours (within 48 hours recommended in the U.S.) Other than the disposable Oves cap, after use cervical caps are washed and stored for reuse. Silicone devices may be boiled to sterilize them. Reusable caps may last for one or two years.
Effectiveness
The effectiveness of cervical caps, as of most forms of contraceptionBirth control
Birth control is an umbrella term for several techniques and methods used to prevent fertilization or to interrupt pregnancy at various stages. Birth control techniques and methods include contraception , contragestion and abortion...
, can be assessed two ways: method effectiveness and actual effectiveness. The method effectiveness is the proportion of couples correctly and consistently using the method who do not become pregnant. Actual effectiveness is the proportion of couples who intended that method as their sole form of birth control and do not become pregnant; it includes couples who sometimes use the method incorrectly, or sometimes not at all. Rates are generally presented for the first year of use. Most commonly the Pearl Index
Pearl Index
The Pearl Index, also called the Pearl rate, is the most common technique used in clinical trials for reporting the effectiveness of a birth control method.-Calculation and usage:...
is used to calculate effectiveness rates, but some studies use decrement table
Decrement table
Decrement tables, also called life table methods, are used to calculate the probability of certain events.-Birth control:Life table methods are often used to study birth control effectiveness...
s.
Contraceptive Technology reports that the method failure rate of the Prentif cervical cap with spermicide is 9% per year for nulliparous
Parity (medicine)
In biology, parity is a technical term that refers to the number of times a female has given birth to a fetus.It can lead to some ambiguity for events occurring between 20 and 24 weeks, and for multiple pregnancies.-Enumeration:...
women (women who have never given birth), and 26% per year for parous women. The actual pregnancy rates among Prentif users vary depending on the population being studied, with yearly rates of 11% to 32% being reported.
Little data is available on the effectiveness of the Oves cap and Femcap. The Oves manufacturer cites one small study of 17 users. The Femcap website does not cite any data on the current version of the Femcap; but lists data for an older version which is no longer approved by the FDA.
The only effectiveness trial of Lea's Shield was too small to determine method effectiveness. The actual pregnancy rate was 15% per year. Of the women in the trial, 85% were parous
Parity (medicine)
In biology, parity is a technical term that refers to the number of times a female has given birth to a fetus.It can lead to some ambiguity for events occurring between 20 and 24 weeks, and for multiple pregnancies.-Enumeration:...
(had given birth). The study authors estimate that for nulliparous women (those who have never given birth) the pregnancy rate in typical use may be lower, around 5% per year.
Acceptability
The Oves cap and the new version of the Femcap performed poorly in user acceptability studies. The study on the Femcap concluded that the modifications to the FemCap significantly increased painPain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
and discomfort among female users and their male sex partners, and that the modifications decreased acceptability of the device compared with the earlier version. The study of the Oves cap reported that few women indicated that they would use the cap in the future.
A pilot study conducted in Britain prior to the Lea's Shield's approval concluded that the Lea's Shield "may be acceptable to a highly select minority of women".
As of 2002, the cervical cap was one of the least common methods of contraception
Contraception
Contraception is the prevention of the fusion of gametes during or after sexual activity. The term contraception is a contraction of contra, which means against, and the word conception, meaning fertilization...
in the United States. A 2002 study indicated that of sexually active American women, 0.6% are currently using either the cervical cap, contraceptive sponge
Contraceptive sponge
The contraceptive sponge combines barrier and spermicidal methods to prevent conception. Three brands are marketed: Pharmatex, Protectaid and Today. Pharmatex is marketed in France and the province of Quebec; Protectaid in the rest of Canada and Europe; and Today in the United States.Sponges work...
, or female condom
Female condom
A female condom is a device that is used during sexual intercourse as a barrier contraceptive and to reduce the risk of sexually transmitted infections and unintended pregnancy...
as their primary method of contraception, and fewer than 1% have ever used a cervical cap.
External links
- Cervical Barrier Advancement Society
- Diaphragms and Caps (Yahoo Group)
- Femcap website
- Oves website