Peroxisome proliferator-activated receptor gamma ligands inhibit estrogen biosynthesis in human breast adipose tissue: possible implications for breast cancer therapy.

Estrogen biosynthesis is catalyzed by aromatase cytochrome P-450 (the product of the CYP19 gene). Adipose tissue is the major site of estrogen biosynthesis in postmenopausal women, with the local production of estrogen in breast adipose tissue implicated in the development of breast cancer. In human adipose tissue, aromatase is primarily expressed in the mesenchymal stromal cells and is a marker of the undifferentiated preadipocyte phenotype. Aromatase expression in adipose tissue is regulated via the distal promoter I.4, under the control of glucocorticoids and class I cytokines such as oncostatin M, interleukin 6, and interleukin 11, as well as tumor necrosis factor alpha. These cytokines, which are expressed in adipose, also inhibit adipocyte differentiation. Therefore, we hypothesized that factors which stimulate adipocyte differentiation should inhibit aromatase expression. These factors include synthetic peroxisome proliferator-activated receptor gamma (PPARgamma) ligands such as thiazolidinediones, e.g., troglitazone and rosiglitazone (BRL49653) and the endogenous PPARgamma ligand 15-deoxy-delta12,14-prostaglandin J2. We have demonstrated by measurement of aromatase activity and by reverse transcription-PCR/Southern blotting that these PPARgamma ligands inhibit aromatase expression in cultured breast adipose stromal cells stimulated with oncostatin M or tumor necrosis factor alpha plus dexamethasone in a concentration-dependent manner, whereas a metabolite of troglitazone that does not activate PPARgamma has no effect. We have also shown that troglitazone inhibits luciferase activity of reporter constructs containing various lengths of the upstream region of promoter I.4 transfected into mouse 3T3-L1 preadipocyte mesenchymal cells, whereas the troglitazone metabolite does not. Because local estrogen production in breast fat is implicated in breast cancer development in postmenopausal women, the actions of PPARgamma ligands suggest that they may have potential therapeutic benefit in the treatment and management of breast cancer.

Pregnancy, breast feeding, and oral contraceptives and the risk of epithelial ovarian cancer.

To quantify the effects of cumulative months of pregnancy, breast feeding, and oral contraceptive use on the risk of developing epithelial ovarian cancer, the authors used data collected for the Cancer and Steroid Hormone Study--a multicenter, population-based, case-control study. Detailed reproductive histories were obtained from 436 women aged 20-54 with epithelial ovarian cancer newly diagnosed between December 1980 and December 1982, and from 3833 women aged 20-54 selected at random from the same geographic areas. Estimated relative risks of epithelial ovarian cancer were 0.6 (95% confidence interval (CI) 0.5-0.8) for women who had ever been pregnant, 0.6 (95% CI 0.5-0.8) for women who had ever breast fed, and 0.5 (95% CI 0.5-0.7) for women who had ever used oral contraceptives. Logistic regression analysis revealed a strong trend in decreasing risk of epithelial ovarian cancer with increasing cumulative months of pregnancy; this effect was less pronounced in women aged 50-54 than in younger women. In contrast, a marked reduction in risk was associated with ever having breast fed or used oral contraceptives, while the decrease in risk from additional months of either of these exposures was less than that for pregnancy.

The independent associations of parity, age at first full term pregnancy, and duration of breastfeeding with the risk of breast cancer. Cancer and Steroid Hormone Study Group.

Although the important influence of a woman's reproductive history on her risk of breast cancer is widely recognized, it is not clear whether this is wholly accounted for by the age at her first full-term pregnancy, or whether there are additional, independent influences of breastfeeding or number of children. To examine the respective contributions to the risk of breast cancer of these reproductive factors, we used logistic regression methods to analyze data from a multicenter case-control study, the Cancer and Steroid Hormone Study. Included in the analysis were 4599 women, 20-55 years of age, identified as having an initial diagnosis of breast cancer by one of eight collaborating population-based cancer registries. The 4536 controls were women of similar ages selected by random dialing of households with telephones in the same eight areas. As expected, age at first full-term pregnancy exerted a strong influence on the risk of breast cancer. However, after it and other potentially confounding factors had been controlled for, parity and duration of breastfeeding also had a strong influence on the risk of breast cancer. Compared with women of parity one, women of parity seven or greater had an adjusted relative risk of breast cancer of 0.59 (95% CL, 0.44-0.79). Compared with parous women who never breastfed, women who had breastfed for 25 months or more had an adjusted relative risk of 0.67 (0.52-0.85). These results do not support the supposed preeminent importance of age at first full-term pregnancy among the reproductive determinants of breast carcinogenesis. Resolution of this issue may have important implications for elucidating hormonal influences on breast cancer and for projecting future trends in the disease.

Agreement between women's histories of oral contraceptive use and physician records.

The histories of oral contraceptive (OC) use provided by women participating in a study of hepatocellular adenoma (HCA) were compared with records obtained from their physicians. In the HCA study two memory aids were used to assist women in their recall: a calendar of significant events during a woman's lifetime to which she might relate her use of OCs and a book of colour photographs of the 90 OC preparations available up to the time of the study. Using the number of months of a woman's history which could be checked against physician records (mean for all women of 33 months) as the denominator, the highest proportion of concordance was for month-specific duration of OC use (90%) with lower agreement for duration and brand (62%) and duration, brand, and dose (54%). Agreement was better for cases than for controls.

PIP: The adequacy of women's verbal accounts in determining oral contraceptive (OC) exposure was assessed by comparing the respondents' histories with prescribers' records. The study participants were selected from 299 women who had participated in a case-control study of hepatocellular adenoma. 2 memory aids were utilized during the interview: a calendar of significant life events to which a woman might relate her OC use and a color photograph book of 90 OC preparations available up to the time of the study. 61 cases and 69 controls were actually included in the study. Agreement for month-specific duration was 90%; for duration and brand, 62%; and for duration, brand and dose, 54%. Each of these categories was significantly different from the others and agreement was significantly higher for cases than for controls. The results compare favorably to 2 other studies, even with the increased complexity of this study, i.e., longer interval between OC use and interviews and a much greater number of brands and doses to choose from. The memory aids proved useful in recall performance.

The intrauterine device and pelvic inflammatory disease revisited: new results from the Women's Health Study.

To examine whether the risk of pelvic inflammatory disease associated with intrauterine device (IUD) use varies with a woman's sexual behavior, we analyzed data from the Women's Health Study, a hospital-based, case-control study carried out in the United States from 1976-1978. The cases were 657 women hospitalized with pelvic inflammatory disease; controls were 2566 women hospitalized with nongynecologic conditions. After controlling for confounding factors, we found no consistent differences in the risk of pelvic inflammatory disease associated with IUD use among women in different categories of gonorrhea history, frequency of intercourse, or number of recent sexual partners. However, among women with only one sexual partner, married and cohabiting women had little appreciable increased pelvic inflammatory disease risk associated with IUD use compared with those using no contraception, whereas previously and never-married women using IUDs had relative risk estimates of 1.8 and 2.6, respectively. These results suggest that women at low risk of acquiring sexually transmitted infections have little increase in the risk of pelvic inflammatory disease from use of an IUD.

Measures of sexual behavior and the risk of pelvic inflammatory disease.

A women's sexual behavior affects her risk of acquiring pelvic inflammatory disease, but the risks have not been well characterized. To study the association between pelvic inflammatory disease and sexual behavior, we analyzed data from a multicenter, case-control study involving 712 women hospitalized with an initial episode of pelvic inflammatory disease and 2719 hospitalized control women without a history of pelvic inflammatory disease. Study participants provided information on their frequency of intercourse, number of recent sexual partners, and previous history of gonorrhea. Logistic regression methods were used to adjust for confounding factors. Women who reported having four or more sexual partners were over three times more likely to be hospitalized for pelvic inflammatory disease (relative risk 3.4; 95% confidence interval 2.2-5.3) than were women who reported only one recent sexual partner. To a lesser extent, frequent sexual intercourse and history of gonorrhea also increased a woman's risk of pelvic inflammatory disease. Frequent intercourse was a strong risk factor for pelvic inflammatory disease among a subgroup of women who were at low risk for acquiring a sexually transmitted disease: Married women with one recent sexual partner with intercourse six or more times per week had a risk of pelvic inflammatory disease of 3.2 (1.4-7.2) compared with similar women having intercourse less than once per week. Frequent intercourse, which does not by itself increase the risk of acquiring a sexually transmitted disease, may increase a woman's risk of pelvic inflammatory disease.

Risk of ectopic pregnancy following tubal sterilization.

To determine the impact of tubal sterilization on the overall incidence of ectopic pregnancy, the authors compared reported incidence rates of ectopic pregnancy after tubal sterilization with the rates associated with other contraceptive methods or no contraception. For each contraceptive method they then calculated the cumulative lifetime risk of ectopic pregnancy from the age at which a final contraceptive choice was made. Tubal sterilization was found to be associated with a lower cumulative lifetime risk of ectopic pregnancy than no contraception or use of an intrauterine contraceptive device. Tubal sterilization carries a somewhat higher risk of ectopic pregnancy than do barrier methods of contraception. Oral contraceptives are associated with a much lower ectopic pregnancy for most than any other contraceptive method or no contraception. Overall, however, the risk of an ectopic pregnancy for most women undergoing tubal sterilization in the United States is estimated to be lower than if they had not been sterilized and had continued their previous contraceptive practices.

Risk of wound and pelvic infection after laparoscopic tubal sterilization: instrument disinfection versus sterilization.

To determine if disinfection, rather than sterilization, of laparoscopic equipment leads to an increase in the risk of postlaparoscopy infection, the authors analyzed data from a multicenter prospective study conducted by the Centers for Disease Control on the safety of sterilizing operations. From September 1978 through July 1981, 3903 women underwent laparoscopic tubal sterilization procedures in which the equipment was sterilized with ethylene oxide (58%) or disinfected with glutaraldehyde (42%). The overall risk of wound infection in each group was 1.5 per 100 women. The relative risk of wound infection for disinfection versus sterilization of the equipment was 0.5 when adjusted for differences in the two groups. The corresponding relative risk of pelvic infection was 1.2. These results suggest that laparoscopy equipment disinfected with glutaraldehyde is not associated with an increased risk of wound or pelvic infection compared with equipment sterilized with ethylene oxide.

Type of intrauterine device and the risk of pelvic inflammatory disease.

To study the association of pelvic inflammatory disease and various types of intrauterine devices (IUDs), data from the Women's Health Study were analyzed. The analysis included data from interviews of 622 women hospitalized with an initial episode of pelvic inflammatory disease and 2369 hospitalized control subjects reporting no history of pelvic inflammatory disease. Compared to the risk in women using no contraception, the relative risk of pelvic inflammatory disease in women currently using the Dalkon Shield was 8.3 (95% confidence limits 4.7 to 14.5). This represented a fivefold increase in risk compared to women currently using other types of IUDs. In this study, only 10% of women wearing an IUD were using the Dalkon Shield, yet they accounted for almost 20% of the excess risk of pelvic inflammatory disease occurring among all the IUD users. Most of the increased risk of pelvic inflammatory disease for women currently using other IUDs (excluding the Dalkon Shield) occurred in the first four months after insertion. These associations were not explained by differences between cases and controls in demographic variables, level of sexual activity, or medical history. The authors recommend that women still using a Dalkon Shield have it removed.

Complications of interval laparoscopic tubal sterilization.

In 1978, the Centers for Disease Control initiated a multicenter prospective study to assess the safety of the various female sterilizing operations and the ways in which they could be made safer. During the first 31 months, 3500 women who underwent interval laparoscopic tubal sterilization by electrocoagulation or Silastic banding without other concurrent operations were enrolled in the study. When a standard definition of complications was used, the overall rate of an intraoperative or postoperative complication was 1.7 per 100 women. Several patients factors increased the risk of complications twofold or more: diabetes mellitus, previous abdominal or pelvic surgery, lung disease, a history of pelvic inflammatory disease, and obesity. There was a fivefold difference in complication rates between procedures performed under general anesthesia and those done under local anesthesia.

Risk factors for complications of interval tubal sterilization by laparotomy.

The complication rate among 282 women undergoing interval tubal sterilization by laparotomy was studied as part of the prospective multicenter Collaborative Review of Sterilization. Using a standard definition of major complications, the overall complication rate was 5.7 per 100 procedures. Women experiencing complications had a significantly lengthened postoperative recovery period before the resumption of normal activities. Important risk factors for complications included diabetes, cigarette smoking, previous abdominal or pelvic surgery, and a history of pelvic inflammatory disease. Women with an initial abdominal incision of 7 cm or longer had three times the complication rate of women with shorter incisions. These results provide objective evidence that, for tubal sterilizations, minilaparotomy (laparotomy with a small abdominal incision) is associated with lower morbidity than is conventional laparotomy.

Menstrual changes after tubal sterilization.

The authors used data from a multicenter prospective study of female sterilization surgery to study changes in menstrual function following tubal sterilization. Duration of menstrual bleeding, menstrual cycle length, cycle regularity, amount of menstrual bleeding, menstrual pain, and intermenstrual bleeding were examined. The authors followed 2456 women for two years after tubal sterilization surgery. Each woman served as her own control; her menstrual function at the two-year follow-up interview was compared with her menstrual function at the preoperative interview. Except for menstrual pain among women who underwent unipolar electrocoagulation procedures, there was no increase in the prevalence of adverse menstrual function after tubal sterilization. For all menstrual variables, 50% or more of women with adverse function preoperatively had an improvement by two years after tubal sterilization.

Vasectomies performed by private physicians, United States, 1980 to 1984.

Using data from the National Disease and Therapeutic Index, we estimated that between 1980 and 1984, 1.9 X 10(6) U.S. men had vasectomies. Men between the ages of 30 and 39 years, and white men, were more likely than others to undergo the procedure. Further national data on this popular procedure are needed.

Regret after decision to have a tubal sterilization.

To determine characteristics associated with regretting sterilization that can be determined preoperatively, we analyzed data from the Collaborative Review of Sterilization (CREST), a multicenter, prospective, observational study. Of 5022 women, 2.0% regretted having had a tubal sterilization at 1 year after the procedure and 2.7% did so after 2 years. Using a multivariate analysis to identify risk factors for regret, we found that almost all characteristics were more closely associated with regret at 1 year than at 2 years postoperatively. Of the characteristics we examined that could be objectively determined preoperatively, we considered only age less than 30 years and (for whites) a concurrent cesarean section to be risk factors for regret at 2 years after sterilization. However, in absolute terms, less than 10% of women with both those risk factors regretted having the procedure.

PIP: To determine characteristics associated with regretting sterilization that can be determined preoperatively, the authors analyzed data from the Collaborative Review of Sterilization (CREST), a multicenter, prospective, observational study. Of 5022 women, 2.0% regretted having had a tubal sterilization at 1 year after the procedure, and 2.7% did so after 2 years. Using a multivariate analysis to identify risk factors for regret, the authors found that almost all characteristics were more closely associated with regret at 1 year than at 2 years postoperatively. Of the characteristics examined that could be objectively determined preoperatively, only age less than 30 years and (for whites) a concurrent cesarean section were considered to be risk factors for regret at 2 years after sterilization. However, in absolute terms, less than 10% of women with both those risk factors regretted having the procedure.

Hysterectomy performed within 1 year after tubal sterilization.

In the United States, approximately 650,000 women of reproductive age undergo tubal sterilization each year and some of these women later have hysterectomies. Little is known about risk factors for having hysterectomy after tubal sterilization. For examination of this issue, we analyzed data from the Collaborative Review of Sterilization, an ongoing multicenter prospective study designed to assess the safety and efficacy of female sterilization operations. In 1979 and 1980, 4002 women 15 to 44 years of age had interval tubal sterilization; of these women, 64 had hysterectomies within 15 months, which yielded a cumulative incidence of 1.6%. Women with a history of menstrual complaints, leiomyomata, ovarian cysts, or endometriosis before their tubal sterilization had an increased risk of hysterectomy, compared with women without such a history. However, 98% of women with a history of these conditions did not have a hysterectomy within 15 months after tubal sterilization. Further follow-up of these women should help to better delineate their long-term risks.

Folate fortification: potential impact on folate intake in an older population.

OBJECTIVE: To examine the potential impact of different models of folate fortification of Australian foods on the folate intakes of older Australians. DESIGN: Dietary data were collected using a food frequency questionnaire from people attending a population-based health study. SETTING: Two postcode areas west of Sydney, Australia. SUBJECTS: A total of 2895 people aged over 49 y, obtained from a door knock census (79% of 3654 subjects examined). MAIN OUTCOME MEASURES: The folate intake in this population was estimated using four different models: (1) pre-fortification folate values; (2) current voluntary folate fortification in Australia; (3) universal fortification of all foods permitted to add folate, at 25% recommended dietary intake (RDI) per reference serve; and (4) universal fortification of all foods permitted to add folate, at 50% RDI per reference serve. The increased bioavailability of synthetic folic acid (SFA) was included in the analysis. RESULTS: At current voluntary folate fortification, approximately 65% of this population consume 320 microg dietary folate equivalents (DFE) or more per day from diet and supplements, and 0.4% (n=10) consume greater than the recommended upper safety level of 1000 microg from SFA. More than 95% of this older population would be expected to consume more than 320 microg DFE from diet and supplements with universal fortification at 50% of the RDI, and 0.5% (n=14) may consume greater than 1000 microg/day of SFA. CONCLUSIONS: There is unlikely to be a large increase in the proportion of older persons who are likely to consume more than the upper safety level of intake with universal folate fortification. As most of those who currently or are predicted to consume over 1000 microg SFA take supplements containing folic acid, it is highly recommended that vitamin B12 be included in any vitamin supplements containing folate. SPONSORSHIP: This study was supported by the Australian National Health and Medical Research Council (NHMRC).

Sterilization-associated deaths: a global survey.

Except for data from several geographically limited studies, little is known globally about the number and causes of death associated with surgical sterilization. To identify clinical characteristics and problems leading to deaths related to the procedures, the International Planned Parenthood Federation ( IPPF ) and the Centers for Disease Control (CDC) in the United States collaborated in a global mail survey of 4642 physicians. Usable responses were received from 1298 physicians (28%) in 80 countries. Fifty-five sterilization-associated deaths which occurred from January 1, 1980 to June 30, 1982 were reported. The most frequently reported causes of death were infection, anesthetic complications, and hemorrhage. There were some regional differences in the relative frequencies of these causes. Most cases did not involve surgical accident. The characteristics most frequently associated with the reported fatal procedures were: interval sterilizations, minilaparotomy incision, tubal ligation and general anesthesia. Most deaths were attributable to the surgical sterilization procedure.

PIP: To obtain information on the number and causes of deaths associated with surgical sterilization, the Centers for Disease Control (CDC) and the International Planned Parenthood Federation (IPPF) collaborated in a global mail survey of 4642 IPPF-affiliated physicians. Usable responses were received from 1298 physicians (28%) in 80 countries. A total of 55 deaths (54 associated with tubal sterilization and 1 with vasectomy) were reported for the period January 1, 1980-June 30, 1982. The largest number of fatalities occurred in Asia (33) and Latin America (15). The median age at death was 32 years. Characteristics most frequently associated with the reported fatal procedures were interval sterilization (25 cases), minilaparotomy incision (19), tubal ligation (34), and general anesthesia (28). 38 of the tubal sterilization-associated deaths and the 1 vasectomy-related death were directly attributable to the sterilization procedure. The most frequently reported causes of death were infection (20 cases), anesthetic complications (12), and hemorrhage (8). Surgical accidents were reported for 17 of the tubal sterilization-associated fatalities. Some regional variation was noted in the relative frequencies of these causes. These data are known to reflect a substantial underreporting of sterilization-related mortality. In addition, the nonavailability of denominator data precluded estimation of the risk of death associated with surgical approach, method of tubal occlusion, timing of the sterilization procedure in relation to last pregnancy, or anesthesia. However, it can be stated that many of the deaths reported in this series could have been prevented by more adequate staff training, use of sterile equipment, and improved follow-up procedures. It is recommended that data on sterilization-related fatalities be reported to a central location to facilitate their aggregation and analysis.

Contraceptive use before tubal sterilization.

A woman's decision to undergo tubal sterilization may be affected by her experience with temporary contraception. To examine this issue we analyzed data from the Collaborative Review of Sterilization, a multicenter, prospective study of the health effects of sterilization operations on women aged 15-44 years. Data on contraceptive use by a comparison group of nonsterilized women were drawn from a random, population-based sample of women aged 20-44 years who were controls in a large study of cancer and steroid hormone use. Sterilized women reported ever using a higher average number of contraceptive methods than did nonsterilized women. As compared with nonsterilized women, a higher percentage of sterilized women reported ever using contraceptives (99% versus 91%), especially two types, barrier and rhythm or withdrawal. Prior to selecting sterilization as a permanent contraceptive method, the sterilized women had more extensive experience with temporary contraceptives, particularly the less effective ones, than did the comparable nonsterilized women.

PIP: This study compared contraceptive use histories in women undergoing tubal sterlization to those obtained from women who had not sought sterilization. The 6080 tubal sterilization cases were drawn from the Collaborative Review of Sterilization (CREST) study; 412 nonsterilized controls were drawn from the control group of the Cancer and Steroid Hormone (CASH) study. 4 types of contraceptive methods were evaluated: oral contraceptives (OCs), IUDs, barrier methods (diaphragm, foam, or condom), and traditional methods (withdrawal and rhythm). Ever-use rates were standardized by age, race, years of education, and gravidity. Compared with nonsterilized women, a higher percentage of women undergoing tubal sterilization reported ever-use of IUDs (35.1% of sterilized women versus 24% of nonsterilized women), barrier methods (66/.1% versus 15.9%, respectively), and rhythm or withdrawl (29.4% versus 14.6%, respectively). Rates of OC use were similar (87.1% among sterilized women versus 84.3% among nonsterilized controls). Further analysis indicated that 1.4% undergoing tubal sterilization compared to 11.9% of the nonsterilized women had never used any contraceptive method. 39.6% of the women in the sterilization group but only 6.2% of the controls had used 3-4 different contraceptive methods. The former group of women were more likely to have higher gravidity and a history of abortion than those who had used fewer methods before their tubal sterilization. These findings suggest that experience with temporary contraceptives may affect the decision to undergo tubal sterilization.

Characteristics of vasectomies performed in selected outpatient facilities in the United States, 1980.

In 1981 the American Association of Gynecologic Laparoscopists and the Division of Reproductive Health, Centers for Disease Control, jointly conducted a study of vasectomies performed in outpatient facilities in 1980 in the United States. One hundred twenty-nine facilities that responded to either a mailed questionnaire or a telephone interview stated that vasectomies were performed there in 1980. The average cost was $273, with a range of $50-1,000. Facilities differed markedly in the use of anesthesia. Freestanding surgical centers reported the use of general anesthesia for 29% of the vasectomies. Other types of facilities were more likely to use local or regional anesthesia. Our data suggest areas for further research to improve the availability and safety of vasectomy.

PIP: In 1981 the American Association of Gynecologic Laparoscopists and the Centers for Disease Control conducted a survey of US clinics providing female and males sterilization procedures. This analysis provides new information on the numbers of vasectomies performed in 1980 in outpatient facilities, types of anesthesia used, cost, and lenght of postoperative stay. Results reveal that in 1980: 1) 10,394 vasectomies were performed in respondent facilities of all types; 70 freestanding surgical centers performed 4347 vasectomiew, and 32 family planning clinics performed 4163 vasectomies; 2) the average reported charge for a vasectomy in respondent facilities was $273, which included the physician's and anesthesia fees; 3) throughout the US, the average cost of a vasectomy was higher in freestanding surgical centers than in other facilities; 4) in all regions, 96% of the facilities other than freestanding surgical centers, reported only the use of local or regional anesthesia; 5) of the 11 facilities reporting that vasectomies cost more than $500, 82% reported that more than 75% of the vasectomies were done using general anesthesia; and 6) the mean postoperative stay for all reported vasectomies was 1.3 hours--facilities reporting higher percentages of general anesthesia use tended to have longer postoperative stays. This data address only 2% of the 520,000 vasectomies estimated to have been performed in the US in 1980. Although vasectomy is often considered a cheap, simple, safe, and effective outpatient procedure, in this study an unexpectedly high use of general anesthesia is found. In addition, vasectomy may be fairly expensive, sometimes costing as much of $1000, and the postoperative observation may not be as long as recommended.

Tubal sterilizations performed in freestanding, ambulatory-care surgical facilities in the United States in 1980.

In 1981 the American Association of Gynecologic Laparoscopists and the Division of Reproductive Health, Centers for Disease Control, jointly conducted a study of tubal sterilizations performed in 141 freestanding, ambulatory-care surgical facilities in 1980 in the United States. Information was collected through mailed questionnaires and telephone interviews. Of 330 potential responding facilities, 141 we identified as freestanding, ambulatory-care surgical facilities. About 16,500 tubal sterilizations were performed in these facilities in 1980. The mean number of tubal sterilizations per freestanding, ambulatory-care surgical facility was 212. Sixty-seven percent of tubal sterilizations were performed in the south and west. General anesthesia was the anesthetic method used in 97% of the procedures. Nearly 91% of tubal sterilizations were done via laparoscopy, with bipolar electrocoagulation the tubal-occlusion method used most frequently. After tubal sterilization the patients were observed for an average of 2.4 hours before discharge. The average cost of laparoscopic tubal sterilization was $801; for nonlaparoscopic tubal sterilization it was $850.