Medial tibial stress syndrome can be diagnosed reliably using history and physical examination.

BACKGROUND: The majority of sporting injuries are clinically diagnosed using history and physical examination as the cornerstone. There are no studies supporting the reliability of making a clinical diagnosis of medial tibial stress syndrome (MTSS). AIM: Our aim was to assess if MTSS can be diagnosed reliably, using history and physical examination. We also investigated if clinicians were able to reliably identify concurrent lower leg injuries. METHODS: A clinical reliability study was performed at multiple sports medicine sites in The Netherlands. Athletes with non-traumatic lower leg pain were assessed for having MTSS by two clinicians, who were blinded to each others' diagnoses. We calculated the prevalence, percentage of agreement, observed percentage of positive agreement (Ppos), observed percentage of negative agreement (Pneg) and Kappa-statistic with 95%CI. RESULTS: Forty-nine athletes participated in this study, of whom 46 completed both assessments. The prevalence of MTSS was 74%. The percentage of agreement was 96%, with Ppos and Pneg of 97% and 92%, respectively. The inter-rater reliability was almost perfect; k=0.89 (95% CI 0.74 to 1.00), p<0.000001. Of the 34 athletes with MTSS, 11 (32%) had a concurrent lower leg injury, which was reliably noted by our clinicians, k=0.73, 95% CI 0.48 to 0.98, p<0.0001. CONCLUSION: Our findings show that MTSS can be reliably diagnosed clinically using history and physical examination, in clinical practice and research settings. We also found that concurrent lower leg injuries are common in athletes with MTSS.

A prospective study on MRI findings and prognostic factors in athletes with MTSS.

In medial tibial stress syndrome (MTSS) bone marrow and periosteal edema of the tibia on the magnetic resonance imaging (MRI) is frequently reported. The relationship between these MRI findings and recovery has not been previously studied. This prospective study describes MRI findings of 52 athletes with MTSS. Baseline characteristics were recorded and recovery was related to these parameters and MRI findings to examine for prognostic factors. Results showed that 43.5% of the symptomatic legs showed bone marrow or periosteal edema. Absence of periosteal and bone marrow edema on MRI was associated with longer recovery (P = 0.033 and P = 0.013). A clinical scoring system for sports activity (SARS score) was significantly higher in the presence of bone marrow edema (P = 0.027). When clinical scoring systems (SARS score and the Lower Extremity Functional Scale) were combined in a model, time to recovery could be predicted substantially (explaining 54% of variance, P = 0.006). In conclusion, in athletes with MTSS, bone marrow or periosteal edema is seen on MRI in 43,5% of the symptomatic legs. Furthermore, periosteal and bone marrow edema on MRI and clinical scoring systems are prognostic factors. Future studies should focus on MRI findings in symptomatic MTSS and compare these with a matched control group.

Predicting return to play after hamstring injuries.

BACKGROUND: Previous studies on the prognostic value of clinical and MRI parameters for the time to return to play (TTRTP) in acute hamstring injuries showed only limited to moderate evidence for the various investigated parameters. Some studies had multiple methodological limitations, including retrospective designs and the use of univariate analysis only. The aim of this study was to assess the prognostic value of clinical and MRI parameters for TTRTP using multivariate analysis. METHODS: 28 clinical and MRI parameters were prospectively investigated for an association with TTRTP in 80 non-professional athletes with MRI positive hamstring injuries undergoing a standardised rehabilitation programme. The association between possible prognostic parameters and TTRTP was assessed with a multivariate linear regression model. Parameters that had a p value <0.2 on univariate testing were included in this model. RESULTS: 74 athletes were available for analysis. A total of nine variables met the criteria for the multivariate analysis: intensity of sports, level of sports, self-predicted TTRTP by the athlete, length of discomfort on palpation, deficit in passive straight leg raise, pain score on isometric knee flexion, isometric knee flexion strength deficit and distance of the proximal pole of the MRI hyperintensity to the tuber ischiadicum. Of these, only self-predicted TTRTP by the athlete and a passive straight leg raise deficit remained significantly associated with TTRTP after stepwise logistic regression. CONCLUSIONS: The clinical parameters self-predicted TTRTP and passive straight leg raise deficit are independently associated with the TTRTP. MRI parameters in grade 1 and 2 hamstring injuries, as described in the literature, are not associated with TTRTP. For clinical practice, prognosis of the TTRTP in these injuries should better be based on clinical parameters.

Cooling during exercise in temperate conditions: impact on performance and thermoregulation.

Exercise-induced increase in core body temperature may lead to the development of hyperthermia (>40.0°C) and/or decreased performance levels. This study examined the effects of wearing a cooling vest during a 5-km time trial on thermoregulatory responses and performance. 10 male masters athletes (42±10 years) performed a 5-km time trial on a motorized treadmill in a climate chamber (25°C, 55% relative humidity) with and without a cooling vest. Split times, heart rate, core-, skin- and cooling vest temperature were measured every 500 m. Subjects also rated thermal comfort and level of perceived exertion. The cooling vest significantly decreased heart rate (p<0.05), decreased skin temperature (p<0.001) and improved thermal comfort (p<0.005) during the time trial. Time to finish the 5-km time trial and pacing strategy did not differ between the control (1 246±96 s) and cooling vest condition (1 254±98 s, p=0.85). Additionally, thermoregulatory responses, maximum core body temperature and level of perceived exertion were not different across conditions (p=0.85, p=0.49, p=0.11, respectively). In conclusion, we demonstrated that wearing a cooling vest during exercise improves thermal comfort but does not enhance performance or decrease core body temperature in male masters athletes under temperate ambient conditions.

Risk factors and prognostic indicators for medial tibial stress syndrome.

The objective of the study was to examine the risk factors and prognostic indicators for medial tibial stress syndrome (MTSS). In total, 35 subjects were included in the study. For the risk factor analysis, the following parameters were investigated: hip internal and external ranges of motion, knee flexion and extension, dorsal and plantar ankle flexion, hallux flexion and extension, subtalar eversion and inversion, maximal calf girth, lean calf girth, standing foot angle and navicular drop test. After multivariate regression decreased hip internal range of motion, increased ankle plantar flexion and positive navicular drop were associated with MTSS. A higher body mass index was associated with a longer duration to full recovery. For other prognostic indicators, no relationship was found.

Shockwave treatment for medial tibial stress syndrome in athletes; a prospective controlled study.

Objective The purpose of this study was to describe the results of two treatment regimens for medial tibial stress syndrome (MTSS); a graded running programme and the same running programme with additional shockwave therapy (extracorporeal shockwave therapy; ESWT). Design A prospective observational controlled trial. Setting Two different sports medicine departments. Participants 42 athletes with MTSS were included. Intervention Patients from one hospital were treated with a graded running programme, while patients from the other hospital were treated with the same graded running programme and focused ESWT (five sessions in 9 weeks). Main Outcome Measures Time to full recovery (the endpoint was being able to run 18 min consecutively without pain at a fixed intensity). Results The time to full recovery was significantly faster in the ESWT group compared with the patients who only performed a graded running programme, respectively 59.7±25.8 and 91.6±43.0 days (p=0.008). Conclusions This prospective observational study showed that MTSS patients may benefit from ESWT in addition to a graded running programme. ESWT as an additional treatment warrants further investigation in a prospective controlled trial with the addition of randomisation and double blinding.

The value of MRI STIR signal intensity on return to play prognosis and reinjury risk estimation in athletes with acute hamstring injuries.

OBJECTIVES: Previous studies have shown low to moderate evidence for a variety of magnetic resonance imaging (MRI) features as prognostic factors in athletes with hamstring injuries. Short-tau inversion recovery (STIR) signal intensity has not yet been investigated for assessing the prognosis of acute muscle injuries. Our aim was to explore the relationship between MRI STIR signal intensity and time to return to play (RTP) and to investigate the association between MRI STIR and reinjury risk in athletes with acute hamstring injuries. STUDY DESIGN: Case-control study. METHODS: We used MRI STIR to measure intramuscular signal intensity in patients with clinically diagnosed hamstring injuries at two time points: at injury and RTP. At injury, we calculated the association of MRI STIR signal intensity with the time to RTP and reinjury risk. At RTP, the association of MRI STIR signal intensity and reinjury risk and the change in MRI STIR signal intensity over time on reinjury risk was evaluated. RESULTS: 51 patients were included. We found increased MRI STIR signal intensity: (1) at time of injury not to be associated with time to RTP, (2) at time of injury to be associated with a slightly lower risk for reinjury: odds 0.986 (0.975-0.998, p=0.02) and (3) at RTP not to be associated with reinjury risk. (4) We found no association between the change in MRI STIR signal intensity over time and reinjury risk. CONCLUSION: Increased MRI STIR signal intensity at injury has no value in time to RTP prognosis, but is associated with a reduced reinjury risk.

Autologous growth factor injections in chronic tendinopathy: a systematic review.

Chronic degenerative tendinopathies are frequent and difficult to treat. Tendon healing and regeneration may be improved by injecting autologous growth factors obtained from the patient's blood. Autologous growth factors can be injected with autologous whole blood or platelet-rich plasma (PRP). Electronic databases were searched for prospective clinical trials on treatment with autologous growth factors of patients with chronic tendinopathy. Chronic tendinopathy in this study included wrist extensors, flexors, plantar fasciopathy and patellar tendinopathy. Studies examining the treatment of other tendinopathies were not identified. The Physiotherapy Evidence Database score was used to examine the methodological quality of the assessment, and a qualitative analysis was performed with the levels of evidence. There are many proposed treatment options for chronic tendinopathy. Treatments in the form of injections with autologous whole blood or PRP are increasingly used in clinical practice. There are high expectations of these regenerative injections, and there is a clear need for effective conservative therapies. All studies showed that injections of autologous growth factors (whole blood and PRP) in patients with chronic tendinopathy had a significant impact on improving pain and/or function over time. However, only three studies using autologous whole blood had a high methodological quality assessment, and none of them showed any benefit of an autologous growth factor injection when compared with a control group. At present, there is strong evidence that the use of injections with autologous whole blood should not be recommended. There were no high-quality studies found on PRP treatment. There is limited evidence to support the use of injections with PRP in the management of chronic tendinopathy. There is growing interest in the working mechanisms of autologous growth factors. The amount and mixture of growth factors produced using different cell separating systems are largely unknown and it is also uncertain whether platelet activation prior to injection is necessary. These variables should be taken into account when starting clinical studies. A good experimental model for studying tendinopathy would be helpful for basic research. Future clinical studies using a proper control group, randomization, blinding and validated disease-specific outcome measures for pain and function are needed.

The additional value of a pneumatic leg brace in the treatment of recruits with medial tibial stress syndrome; a randomized study.

OBJECTIVE: To study the additional effect of a pneumatic leg brace with standard rehabilitation for the treatment of medial tibial stress syndrome (MTSS) in recruits. METHODS: In a single blinded randomized study, 15 recruits (age 17-22) followed a rehabilitation programme consisting of leg exercises and a graded running programme. Recruits performed daily exercises and ran three times a week. The running programme consisted of 6 consecutive phases. One group was, after randomization, additionally provided with a pneumatic leg brace. Follow-up was provided every other week. Days to completing the running programme was the primary outcome measure, the Sports Activity Rating Scale (SARS) score and satisfaction with the treatment were secondary outcome measures. RESULTS: In total 14 recruits completed the rehabilitation programme. No differences were found in the number of days until phase six of the running schedule was finished between the brace and the control group (Brace 58.8 +/- 27.7 (mean +/- SD) vs Non-Brace 57.9 +/- 26.2 (mean +/- SD, p = 0.57). Also no differences were found in the SARS scores between the groups. Overall satisfaction with the treatment was 6.4 +/- 1.1 (mean +/- SD) on a 1-10 scale for the brace group and 7.1 +/- 0.7 (mean +/- SD) for the control group (p = 0.06). Comfort of the brace was assessed as 4.8 +/- 1.3 (mean +/- SD) on a 1-10 scale. CONCLUSIONS: No additional large effect of the pneumatic leg brace could be found in recruits and wearing of the brace was not feasible, since the wearing comfort was low.

Platelet-Rich plasma Injection Management for Ankle osteoarthritis study (PRIMA): protocol of a Dutch multicentre, stratified, block-randomised, double-blind, placebo-controlled trial.

INTRODUCTION: Platelet-rich plasma (PRP) is a potentially efficacious treatment for ankle osteoarthritis (OA), but its use has not been examined in high-quality studies. Systematic reviews show that PRP injections significantly decrease pain and improve function in patients with knee OA. Ankle OA is more common than hip or knee OA in the young active population; with a prevalence of 3.4%.PRP injections in ankle OA are shown to be safe and improve quality of life over time, but no randomised controlled trial has been conducted. Our randomised controlled trial will evaluate the efficacy of PRP injections for symptom reduction and functional improvement, compared with placebo, in the treatment of ankle (talocrural) OA. METHODS AND ANALYSIS: We will conduct the Platelet-Rich plasma Injection Management for Ankle OA study: a multicentre, randomised, placebo-controlled trial. One hundred patients suffering from ankle OA will be randomised into two treatment groups: PRP injection or placebo (saline) injection. Both groups will receive two injections of PRP or placebo at an interval of 6 weeks. Primary outcome is the American Orthopaedic Foot and Ankle Society score at 26 weeks. Secondary outcomes determined at several follow-up moments up to 5 years, include Ankle Osteoarthritis Score, Foot and Ankle Outcome Score, pain subscale of (0-40), Visual Analogue Scale score (0-100), Ankle Activity Score (0-10), subjective patient satisfaction Short Form Health Survey-36, Global Attainment Scaling and the EuroQol-5 dimensions-3 levels utility score. A cost-effectiveness analysis will be performed at 1 year. ETHICS AND DISSEMINATION: The study is approved by the Medical Ethics Review Committee Amsterdam Medical Center, the Netherlands (ABR 2018-042, approved 23 July 2018) and registered in the Netherlands trial register (NTR7261). Results and new knowledge will be disseminated through the Dutch Arthritis Association (ReumaNederland), Dutch patient federation, conferences and published in a scientific peer-reviewed journal. TRIAL REGISTRATION NUMBER: NTR7261.

The extent and clinical significance of adenomyotic lesions in the uterine wall. A quantitative assessment.

This report presents an attempt to assess quantitatively the extent of adenomyotic lesions in hysterectomy specimens from women with symptoms suggesting adenomyosis (n = 14) and from women operated on for other reasons (n = 12). The specimens were cut into 5 mm-thick slices in which adenomyotic lesions were localized and counted microscopically. Nineteen uteri contained from 1 to 890 lesions. The distribution of lesions was mostly focal and patchy. More than half of the cases with adenomyotic lesions would have remained unrecognized if only the slice from the axial plane had been examined. Seventy-two per cent of the lesions were found in the posterior wall. Leiomyomas were found in 68% of the uteri with adenomyotic lesions. As adenomyotic lesions were observed with equal frequency in patients with and without pelvic pain, and as the degree of adenomyotic involvement did not correlate with complaints of pain, the significance of adenomyotic lesions as a cause of gynecological symptoms may be questioned.

Menometrorrhagia in the perimenopause is associated with increased serum estradiol.

OBJECTIVE: The purpose of this study was to evaluate the possible association between menometrorrhagia and the level of endogenous estrogen in perimenopausal women. METHODS: A prospective controlled study in which 28 perimenopausal women > 40 years presenting with menometrorrhagia were compared with 28 age-matched (+/- 2 years) women with normal cyclical menstrual periods concerning levels of estradiol and follicle-stimulating hormone (FSH). Neither of the two groups had received sexual hormone treatment at least in 2 weeks preceding the hormonal assessment. RESULTS: The serum level estradiol in the patients was significantly higher than in the controls (0.55 nmol/l versus 0.24 nmol/l), whereas FSH was not significantly different between the two groups (21.2 IU/l versus 11.8 IU/l). Twenty of the 28 patients had performed at histologic examination of the endometrium, and 10 of these (50%) had signs of endometrial hyperplasia. No relationship was found between the endometrial histology and the estradiol level. CONCLUSIONS: An association between a high endogenous estradiol level and menometrorrhagia in the perimenopause was demonstrated. This may have implications for the choice of treatment in this group of women. It is proposed that this type of bleeding disturbances should be controlled by progestins only, and not with combined estrogen-progestin treatment. Suppression of the associated hyperestrogenism could be achieved by use of oral contraceptives or GnRH agonists.

Knowledge, attitudes and management strategies in Scandinavia concerning hormone replacement therapy: a comparison between gynecologists in Denmark, Norway and Sweden.

OBJECTIVES: To describe and compare attitudes, knowledge and management strategies concerning the prescription of hormone replacement therapy (HRT) between gynecologists from three Scandinavian countries. DESIGN AND METHODS: In a cross-sectional study gynecologists in Denmark (n=386), Norway (n=475) and Sweden (n=1323) were invited by letter to complete and return an enclosed questionnaire. Then 1653 of the 2184 (76%) contacted gynecologists completed and returned the questionnaire. RESULTS: of the 1653 Scandinavian gynecologists, 42% offered HRT to all women provided there was no contraindication, while 58% recommended HRT to selected women after considering the advantages and disadvantages of HRT. In Norway and Sweden, the proportion of gynecologists routinely prescribing HRT for women without contraindications increased with age and in the oldest age group of gynecologists (>55 years) 49 and 56%, respectively, recommended HRT to all women. The gynecologists were unanimous in their choice of the type of HRT for perimenopausal women as 94% preferred cyclical or sequential combined (estrogen/progestogen) treatment or estrogen monotherapy (orally or transdermally) for hysterectomized women (95%). For postmenopausal women, 75% of the gynecologists offered continuous combined HRT while cyclical combined therapy was chosen by 15% of the gynecologists. No significant differences were found between physicians in the three countries regarding indications and contraindications to HRT. CONCLUSIONS: Scandinavian gynecologists are generally well informed concerning HRT and liberally recommend HRT for women without contraindications.

Is a long period without childbirth a risk factor for developing endometriosis?

Endometriosis was found in 42 (20%) of 206 symptom-free, parous Norwegian women with a mean age of 37 years at the time of sterilization. Case-control analysis between the 42 women with endometriosis and the 164 without endometriosis revealed an increased risk of endometriosis with increasing number of years since the last childbirth. After 10 years without a birth, the odds ratio for endometriosis was 4.5 compared with the first 5 years after the last delivery. An increased risk of endometriosis with increasing age of the women could not be detected. If these findings from women with voluntary infertility are transferred to women with endometriosis associated with involuntary infertility, endometriosis could be a consequence of a long period without childbirth. This might explain why endometriosis is often diagnosed in infertile women.

Endometriosis in women at interval sterilization.

The prevalence of endometriosis was investigated in 108 Norwegian women admitted for interval tubal sterilization. The mean age of the patients was 37 years. Endometriosis was detected in 19 (18%) of the women. About one-half of these had no symptoms from the disease. A positive correlation was found between a retroversion of the uterus and endometriosis. The women with endometriosis showed a longer period of uninterrupted menstrual cycles prior to the time of sterilization, when compared with the controls (89 unaffected women). Sisters and mothers of patients with endometriosis displayed a higher frequency of benign gynecological disorders than the corresponding relatives of the control group. The prevalence of endometriosis appeared to be independent of the following clinical parameters: onset of menarche, age at first pregnancy, number of pregnancies, previous use of hormonal contraceptives or IUD, and actual age at the time of sterilization.

Endometriosis in monozygotic twins.

OBJECTIVE: To study the reproductive and medical history of monozygotic twin sisters and mothers of patients with endometriosis. MATERIAL AND METHODS: Among 515 patients with endometriosis, eight had a monozygotic twin sister all of whom had had a gynecological laparoscopy or laparotomy. In addition, five of their mothers had had a laparotomy. Details about these 13 relatives were obtained either from medical records (ten cases) or by unmistakable reports from the proband (three cases). RESULT: Six of the monozygotic twin sisters (75%) also had symptomatic endometriosis compared with 3.8% among other types of sisters (p < 0.0005). Three of the mothers (38%) had either endometriosis or adenomyosis. CONCLUSION: This study gives support to the assumption that endometriosis has a genetic trait.

The familial risk of endometriosis.

OBJECTIVE: To study the occurrence of endometriosis or adenomyosis in mothers and sisters of patients with endometriosis. METHODS: A total of 563 patients with endometriosis were interviewed about endometriosis or adenomyosis in their mothers or sisters. Five hundred and twenty-eight patients (94%) gave information about their relatives. Six patients were adopted and had no knowledge about their relatives. Among 522 patients were seven pairs of sisters, of which only one was included, giving a total of 515 cases. The control group consisted of 149 women without endometriosis documented at a recently diagnostic laparoscopy performed in connection with sterilization. The controls were likewise interviewed about their relatives, and none refused to give information. If a gynecological operation in a relative was reported, medical records were obtained (68%) or a description of the medical history was given by the proband. RESULTS: Endometriosis or adenomyosis was disclosed in 3.9% of mothers of cases and in 0.7% of mothers of controls, in 4.8% of sisters of cases and in 0.6% of sisters of controls. The relative risk of endometriosis in a first-degree relative (expressed as odds ratio), was 7.2 (95% confidence interval 2.1, 24.3). Severe manifestations of endometriosis were found more often among patients with a positive family history than among those without (26% versus 12%, p < 0.01). CONCLUSION: The study demonstrates a seven fold increased risk of endometriosis in mothers and sisters of patients with endometriosis. It is assumed that daughters of patients with endometriosis have a similar risk of developing endometriosis.

Endometriosis in pregnant and non-pregnant women at tubal sterilization.

The prevalence of endometriosis was investigated in 208 women at the time of laparoscopic tubal sterilization. In 101 women who were in the first trimester of pregnancy, 16% endometriosis was found. In 107 non-pregnant women, 22% endometriosis was detected. Endometriosis in the pregnant women showed more superficial, non-pigmented, gland-like lesions than in the non-pregnant group. In 23% of the endometriotic lesions from pregnant women, no decidualization was found. No special risk factors for developing endometriosis were found.

PIP: Between 1986-1989, physicians compared endometriosis in 101 pregnant patients (12 weeks) and 107 nonpregnant patients at the University Hospital in Trondheim, Norway both of whom had undergone laparoscopic tubal sterilizations (bipolar coagulation) to determine prevalence of endometriosis in women undergoing sterilization. They also wanted to assess possible predisposing risk factors to endometriosis. The pregnant women underwent dilation and curettage concurrently with sterilization. Even though a higher percentage of the nonpregnant women (22%) had endometriosis than the pregnant women (16%), the difference was not significant. 1 pregnant case even had severe endometriosis. Significant histological differences between pregnant and nonpregnant women existed, however. Clear or red gland like peritoneal nonfibrotic, nonpigmented endometriotic lesions and no pockets characterized the endometriosis in 44% of the pregnant women indicating an early stage of endometriosis while such features occurred in just 4% of nonpregnant women (p.01). Further no decidual reaction was evident in 23% of the endometriotic lesions of pregnant women. 75% of nonpregnant women had brown, blue, or black pigmented lesions indicating an advanced stage of endometriosis while only 31% of pregnant women did (p.02). Nonpregnant women also were more likely to have fibrosis, yet the difference was not statistically significant. Even though women with endometriosis tended to have a retroverted uterus (31% vs. 14%) and the intervals of uninterrupted menstrual cycles were longer than those without endometriosis (106 vs. 87.8 months), the differences were insignificant. In conclusion, endometriosis is relatively common in women undergoing sterilization and in women in early pregnancy. The doctors did not find risk factors for endometriosis.

Histologic confirmation of endometriosis in different peritoneal lesions.

The aim of this study was to compare the macroscopic evaluation of peritoneal abnormalities suspected of endometriosis with the histologic examination of the tissue. Peritoneal biopsies from 152 patients investigated for gynecological problems (94) or undergoing tubal sterilization (58) were taken from macroscopically abnormal peritoneum, and examined for the presence of endometriosis. Endometriosis was histologically confirmed by the presence of both endometrioid glands and stroma. Endometriosis was confirmed in 78 of the patients (51%). If the diagnostic criteria were extended also to include endometrioid stroma lacking glands, but containing iron pigment and/or hemorrhage, 82 patients (54%) were positive for endometriosis. Endometriosis was histologically confirmed in 76% of pigmented lesions, in 57% of clear or red papules, in 12% of peritoneal pockets, and in 16% when only fibrosis or scarring was observed. Half of the samples with confirmed endometriosis exhibited cyclic activity. The reproducibility of the histologic evaluation was satisfactory. A high rate of negative biopsies emphasizes the need of taking biopsies from peritoneal lesions suspected of endometriosis for confirmation of the diagnosis.

Epidemiology of endometriosis in a Norwegian county.

OBJECTIVE: To estimate the prevalence and incidence of endometriosis in Norwegian women aged 40 to 42, and to evaluate reproductive events and life-style as risk factors for endometriosis as well as to evaluate related health-problems. MATERIAL AND METHODS: The study was performed partly as a cross-sectional study to estimate occurrence of endometriosis, partly as a case-control study to look for factors associated with endometriosis. The study group consisted of all female inhabitants--born 1950 to 1952--living in the county of Sør-Trøndelag. In connection with a cardiovascular screening program information about reproductive events and gynecological problems including endometriosis and infertility was obtained. RESULTS: Totally 5139 women were asked to participate, and a questionnaire was completed by 4034 (78.5%). Endometriosis was reported by 2.0% of the women. Life-time risk for endometriosis was estimated to 2.2%. The annual incidence of new cases of endometriosis in this age group is less than 0.3%. There was a significant association between endometriosis and menarche before age 13, and frequent menstrual periods. Nulliparity was more common in women with endometriosis as were infertility problems and pelvic pain. No significant association was found between endometriosis and exercise, smoking, body mass index and education. There was a high risk for women with endometriosis having had cervical conization or gynecological laparotomies such as infertility surgery, operations on ovaries as well as hysterectomies. CONCLUSION: In Sør-Trøndelag county the prevalence of endometriosis is 2.0% and the annual incidence is less than 0.3% for women in their early forties. A woman's life-time risk for endometriosis might be 2.2%. Early menarche, frequent menstruations, pelvic pain, infertility and nulliparity are associated with endometriosis.