Introduction

Cervical caps have been used as birth control for centuries; Asian and Middle Eastern women fashioned caps from herbal and food products thousands of years ago. The contemporary cap was developed in the 1870s, concurrently with the diaphragm, and has been in use in Europe for over 100 years.

In the United States, the cervical cap was first used about 50 years ago. Because contraceptive leaders like Margaret Sanger preferred the diaphragm to the cap, and doctor insertion of the cap was standard, the cap's slide to obscurity was hastened. With introduction of the IUD and oral contraceptives in the 1960s, the cap and other barrier methods fell from popularity. The cervical cap was reintroduced into the United States in the late 1970s, as a result of consumer enthusiasm about its convenience compared to other barrier methods, and its safety as a nonsystematic contraceptive.

After a lengthy investigation of its safety and efficacy, the Prentif ^TM Cavity-Rim cervical cap received approval from the Food and Drug Administration (FDA) for contraceptive use on May 23, 1988.

Definition

The Prentif ^TM Cavity Rim cervical cap is a helmet-shaped, rubber device which, when used with spermicide, acts as a physical and chemical barrier to sperm. The groove on the inside of the cap creates a seal which helps keep the cap in place. The cap is available in 4 sizes (22mm., 25mm., 28mm., and 31mm.); cap length ranges from 3.1 to 3.8 cm.

Effectiveness

A randomized, comparitive study of the cervical cap and diaphragm sponsored by the National Institutes of Health demonstrated a one year pregnancy rate for the cap of 17.4 per 100 users (1). The diaphragm pregnancy rate, 16.7 per 100 users, was similar to that of cap users. Data from other cap studies (2-15) demonstrate pregnancy risks at one year between 8.1% and 19.1%. The largest of these clinical trials, carried out in Los Angeles between 1981 and 1988, found an overall pregnancy risk of 11.3% at 12 months (2). Risks of 8.3% and 3.8% for user and method failures, respectively, were also reported in this study.

Benefits of Cap Use

A major benefit of cap use centers around its convenience compared to other barrier methods. The cap can be left in place for 48 hours and spermicide need not be replaced during this period. As a result, sexual intercourse is less messy and more spontaneous.

It is likely that cap use confers similar noncontraceptive benefits as does diaphragm use; that is, protection against some sexually transmitted diseases including pelvic inflammatory disease (PID).

Risks of Cap Use

There are several potential side effects associated with cap use:

• Conversion from normal to abnormal cervical cytology;
• Urinary tract infections;
• Cervical or vaginal lesions associated with prolonged cap use;
• Allergy to latex rubber or spermicide;
• Toxic Shock Syndrome; and
• Pregnancy

Conversion from Normal to Abnormal Cervical Cytology

In the NIH study (1), 4% of women who had entered the study with a negative Pap smear converted to Class III in the first 3 months of cap use. This rate was twice that of diaphragm users. Review of the Pap slides, along with colposcopy and biopsy results, led to the theory that the cervical epithelium may be more responsive to human papilloma virus in cap users. At present, this is only one of many possible explanations for these changes. Consequently, the FDA mandates a Pap smear prior to cap fitting; initial cap use should be discontinued if the result is other than Class I. The Pap smear should be repeated at 3 months and annually thereafter.

Urinary Tract Infections (UTI)

When comparing diaphragm and cap users, Berstein (1) did not find a difference in UTI prevalence between the two groups. However, for some women in whom diaphragm use causes or exacerbates UTIs, the cap may be a visible alternative.

Cervical/Vaginal Lesions

Bernstein (1) detected abrasions and lacerations associated with the Vimule cap. Not currently approved for use in the United States. The Vimule is a cervical cap with a more sharply edged rim than the Prentif ^TM cervical cap. The Prentif ^TM cap does not usually cause cervical lacerations.

Allergy to Rubber or Spermicide

If a woman is allergic to a particular spermicide, switching to a different, unperfumed brand may help. Some women may choose to use the cap without spermicide; studies suggest that this will reduce the cap's contraceptive effectiveness. If a woman has an allergy to latex rubber, the cap should not be used.

Toxic Shock Syndrome (TSS)

Although non-menstrual TSS has occurred in women using diaphragms or contraceptive sponges, there have been no documented cases of TSS related to cap use. While the risk is only theoretical, there are steps that can be taken to reduce the likelihood of developing TSS. For example, women should be strongly discouraged from wearing the cap longer than 48 hours, using the cap during menses, and using the cap with a personal history of TSS. In addition, women should be warned of the signs of TSS: fever, diarrhea, vomiting, muscle aches and a sunburn-like rash. If these signs occur, the cap should be removed immediately and the clinician notified promptly.

Pregnancy

Use of the cap may result in pregnancy.

Contraindications to Cap Use

Medical Contraindications

• History of Toxic Shock Syndrome;
• Allergy to rubber (latex) or spermicide., and
• Suspected or known cervical or uterine malignancy.

Anatomical/User Contraindications

• Unusually long or short cervix. A long cervix may interfere with an adequate seal of the rim at the fornices, thereby inhibiting contraceptive effectiveness. A short cervix may not provide enough surface for the cap to grip; consequently, dislodgement is more likely to occur.
• Severe cervical laceration or vaginal septum. In these cases, appropriate fit is unlikely to be achieved.
• Irregularly shaped cervix or cervical lesions. While DES exposure is not a contraindication to cap use, there are instances where the asymmetrical cockscomb cervix will interfere with fit. Also, nabothian cysts may be a contraindication to cap fitting if they are large and/or located in such a way as to prohibit fit.
• Inability of woman/partner to insert or remove cap. Most problems related to correct insertion are due to), 1) poor conceptualization on the woman's part of where her cervix is and how the cap covers it, 2) simple inability to reach the cervix, or 3) an aversion to touching her genitals. Often, these problems can be overcome with extra instruction and support.
• Inability to understand/carry out instructions for use.
• Poor cap fit. The clinician should learn to assess correct placement and fit of the cap.

The following are conditions that, until resolved, preclude cap use:

• Acute cervicitis, vaginitis, or pelvic infection,
• Abnormal Pap smear or undiagnosed vaginal/cervical lesions;
• Cervical biopsy or cryosurgery within the past 12 weeks-a negative Pap smear must precede use;
• Full-term delivery within the past six weeks; and
• Discomfort with touching genitals.

Summary

The cap, when used correctly and consistently, can be a highly effective method of contraception. It is an attractive option for women wishing or needing to avoid the systemic effects of some family planning methods. Although the cap shares some of the drawbacks common to all barrier contraceptives, it is comparatively more convenient, more aesthetically pleasing, less expensive to use and allows for greater sexual spontaneity. Attesting to the effectiveness and appeal of cervical caps, researchers are currently working on new cervical cap designs.

The cervical cap increases the range of contraceptive options for all women by providing a safe, effective, and convenient form of contraception.

Provided by NIH.