Computerized planimetry versus clinical assessment for the measurement of cervical ectopia.

OBJECTIVE: As part of a study to assess the role of cervical ectopia in the acquisition of cervical infections, we determined the reliability of cervical ectopia measurements made by computer planimetry and by clinical (visual) assessment. STUDY DESIGN: We conducted pelvic examinations of 1004 women seeking contraceptive services at two health centers in Baltimore. After application of acetic acid, clinicians estimated the relative area of ectopia by visual inspection and took cervical photographs. Two independent raters measured the absolute and relative areas of ectopia from the digitized images by means of an analytic software program. Agreement levels between raters, between multiple readings by the same rater, and between the two measurement methods were quantified by means of the intraclass correlation coefficient and weighted kappa. RESULTS: Intrarater agreement was excellent for computer planimetry measurements of the absolute (intraclass correlation coefficient, 0.97) and relative (intraclass correlation coefficient, 0.89) areas of ectopia. Interrater agreement was also high for computer planimetry measurements of the absolute (intraclass correlation coefficient, 0.83) and relative (intraclass correlation coefficient, 0.85) areas of ectopia. Agreement levels were moderate between clinician assessment and computer planimetry measurements of the relative area of ectopia (kappa = 0.48), but agreement was better when clinical assessment was limited to observations by a single, experienced clinician. CONCLUSION: Measurement of cervical ectopia by computer planimetry was highly reliable and appears appropriate for assessment of the role of ectopia in the acquisition of cervical infections. Clinical assessment of cervical ectopia may be used when computer planimetry is not available.

The mechanism of action of hormonal contraceptives and intrauterine contraceptive devices.

Modern hormonal contraceptives and intrauterine contraceptive devices have multiple biologic effects. Some of them may be the primary mechanism of contraceptive action, whereas others are secondary. For combined oral contraceptives and progestin-only methods, the main mechanisms are ovulation inhibition and changes in the cervical mucus that inhibit sperm penetration. The hormonal methods, particularly the low-dose progestin-only products and emergency contraceptive pills, have effects on the endometrium that, theoretically, could affect implantation. However, no scientific evidence indicates that prevention of implantation actually results from the use of these methods. Once pregnancy begins, none of these methods has an abortifacient action. The precise mechanism of intrauterine contraceptive devices is unclear. Current evidence indicates they exert their primary effect before fertilization, reducing the opportunity of sperm to fertilize an ovum.

PIP: The mechanism of action of contraceptive method is essential for the development of new methods. It also influences cultural and individual acceptability of a contraceptive method. Modern hormonal contraceptives and intrauterine contraceptive devices have multiple biologic effects. Some of them may be the primary mechanism of contraceptive action, whereas others are secondary. For the combined oral contraceptives and progestin-only methods, the main mechanism of action are the inhibition of follicular development, ovulation, and as consequence, corpus luteum formation. Further, it is also involved in the alteration of the cervical mucus that inhibit sperm penetration. For hormonal methods, particularly the low-dose progestin-only products and emergency contraceptive pills have effects on the endometrium that, theoretically, could affect implantation. However, no scientific evidence will indicate that prevention of implantation actually results from the use of these methods. Once implantation has taken place, none of these methods are effective and pregnancy proceeds normally. The precise mechanism of IUDs remains unclear because of difficulties in carrying out relevant investigations in humans and the limitations of extrapolating findings from animal studies. However, several studies evidenced that IUDs exert their primary effect before fertilization, by impeding the ascent of sperm to the fallopian tubes or by reducing the ability of sperm to fertilize an ovum.