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Dive into the research topics where Carolien A. M. Koks is active.

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Featured researches published by Carolien A. M. Koks.


European Journal of Obstetrics & Gynecology and Reproductive Biology | 1998

A randomized comparison of nifedipine and ritodrine for suppression of preterm labor

Carolien A. M. Koks; Hans A.M. Brölmann; Martin J.K de Kleine; Petra A. P. Manger

OBJECTIVES To compare the efficacy and safety of nifedipine and ritodrine in preventing preterm labor, and to evaluate maternal side effects and neonatal outcome. STUDY DESIGN Non-blind, randomized controlled trial RESULTS A randomized trial of 102 pregnant women with gestational ages under 34 weeks, including 24 with twin pregnancies and 45 on betasympathicomimetic drugs, who had regular uterine contractions with either observed cervical changes or preterm rupture of membranes. After stratification women were randomly assigned to receive either ritodrine intravenously or nifedipine orally. Fifty-five women were randomized to the nifedipine group and 47 to the ritodrine group. As expected, both groups were comparable in terms of several entry variables, including mean gestational age, ruptured membranes, treatment with tocolytic drugs, cervical examination, contraction frequency, age, and twin gestation. Delivery of women in the nifedipine group was delayed for 48 h, 7 days, and until 34 weeks gestation in 33 (60%), 26 (47%) and 21(38%) cases, respectively, compared with 31 (66%), 21(45%) and 11(23%) women in the ritodrine group (no significant difference). Maternal side effects were significantly less common in the nifedipine group than in the ritodrine group, however after 7 days of therapy there was no difference between the two groups. Neonatal outcome was similar in the two groups, with four neonatal deaths in the nifedipine and five in the ritodrine group. CONCLUSIONS Nifedipine seems to be as effective as ritodrine in the treatment of preterm labor and is associated with less frequent side effects.


The New England Journal of Medicine | 2015

A Randomized Trial of Progesterone in Women with Recurrent Miscarriages

Arri Coomarasamy; Helen Williams; Ewa Truchanowicz; Paul Seed; Rachel Small; Siobhan Quenby; Pratima Gupta; Feroza Dawood; Yvonne E Koot; Ruth Bender Atik; Kitty W. M. Bloemenkamp; Rebecca Brady; Annette Briley; Rebecca Cavallaro; Ying Cheong; Justin Chu; Abey Eapen; Ayman Ewies; Annemieke Hoek; Eugenie M. Kaaijk; Carolien A. M. Koks; Tin-Chiu Li; Marjory MacLean; Ben Willem J. Mol; Judith Moore; Jackie Ross; Lisa Sharpe; Jane Stewart; Nirmala Vaithilingam; Roy G. Farquharson

BACKGROUND Progesterone is essential for the maintenance of pregnancy. However, whether progesterone supplementation in the first trimester of pregnancy would increase the rate of live births among women with a history of unexplained recurrent miscarriages is uncertain. METHODS We conducted a multicenter, double-blind, placebo-controlled, randomized trial to investigate whether treatment with progesterone would increase the rates of live births and newborn survival among women with unexplained recurrent miscarriage. We randomly assigned women with recurrent miscarriages to receive twice-daily vaginal suppositories containing either 400 mg of micronized progesterone or matched placebo from a time soon after a positive urinary pregnancy test (and no later than 6 weeks of gestation) through 12 weeks of gestation. The primary outcome was live birth after 24 weeks of gestation. RESULTS A total of 1568 women were assessed for eligibility, and 836 of these women who conceived naturally within 1 year and remained willing to participate in the trial were randomly assigned to receive either progesterone (404 women) or placebo (432 women). The follow-up rate for the primary outcome was 98.8% (826 of 836 women). In an intention-to-treat analysis, the rate of live births was 65.8% (262 of 398 women) in the progesterone group and 63.3% (271 of 428 women) in the placebo group (relative rate, 1.04; 95% confidence interval [CI], 0.94 to 1.15; rate difference, 2.5 percentage points; 95% CI, -4.0 to 9.0). There were no significant between-group differences in the rate of adverse events. CONCLUSIONS Progesterone therapy in the first trimester of pregnancy did not result in a significantly higher rate of live births among women with a history of unexplained recurrent miscarriages. (Funded by the United Kingdom National Institute of Health Research; PROMISE Current Controlled Trials number, ISRCTN92644181.).


The Lancet | 2014

Salpingotomy versus salpingectomy in women with tubal pregnancy (ESEP study): an open-label, multicentre, randomised controlled trial.

Femke Mol; Norah M. van Mello; Annika Strandell; Karin Strandell; D. Jurkovic; Jackie Ross; Kurt T. Barnhart; T.M. Yalcinkaya; Harold R. Verhoeve; Giuseppe C.M. Graziosi; Carolien A. M. Koks; Ingmar Klinte; Lars Hogström; Ineke C. A. H. Janssen; Harry Kragt; Annemieke Hoek; Trudy C.M. Trimbos-Kemper; Frank J. Broekmans; Wim N.P. Willemsen; Willem M. Ankum; Ben W. J. Mol; Madelon van Wely; Fulco van der Veen; Petra J. Hajenius

BACKGROUND Tubal ectopic pregnancy can be surgically treated by salpingectomy, in which the affected Fallopian tube is removed, or salpingotomy, in which the tube is preserved. Despite potentially increased risks of persistent trophoblast and repeat ectopic pregnancy, salpingotomy is often preferred over salpingectomy because the preservation of both tubes is assumed to offer favourable fertility prospects, although little evidence exists to support this assumption. We aimed to assess whether salpingotomy would improve rates of ongoing pregnancy by natural conception compared with salpingectomy. METHODS In this open-label, multicentre, international, randomised controlled trial, women aged 18 years and older with a laparoscopically confirmed tubal pregnancy and a healthy contralateral tube were randomly assigned via a central internet-based randomisation program to receive salpingotomy or salpingectomy. The primary outcome was ongoing pregnancy by natural conception. Differences in cumulative ongoing pregnancy rates were expressed as a fecundity rate ratio with 95% CI, calculated by Cox proportional-hazards analysis with a time horizon of 36 months. Secondary outcomes were persistent trophoblast and repeat ectopic pregnancy (expressed as relative risks [RRs] with 95% CIs) and ongoing pregnancy after ovulation induction, intrauterine insemination, or IVF. The researchers who collected data for fertility outcomes were masked to the assigned intervention, but patients and the investigators who analysed the data were not. All endpoints were analysed by intention to treat. We also did a (non-prespecified) meta-analysis that included the findings from the present trial. This trial is registered, number ISRCTN37002267. FINDINGS 446 women were randomly assigned between Sept 24, 2004, and Nov 29, 2011, with 215 allocated to salpingotomy and 231 to salpingectomy. Follow-up was discontinued on Feb 1, 2013. The cumulative ongoing pregnancy rate was 60·7% after salpingotomy and 56·2% after salpingectomy (fecundity rate ratio 1·06, 95% CI 0·81-1·38; log-rank p=0·678). Persistent trophoblast occurred more frequently in the salpingotomy group than in the salpingectomy group (14 [7%] vs 1 [<1%]; RR 15·0, 2·0-113·4). Repeat ectopic pregnancy occurred in 18 women (8%) in the salpingotomy group and 12 (5%) women in the salpingectomy group (RR 1·6, 0·8-3·3). The number of ongoing pregnancies after ovulation induction, intrauterine insemination, or IVF did not differ significantly between the groups. 43 (20%) women in the salpingotomy group were converted to salpingectomy during the initial surgery because of persistent tubal bleeding. Our meta-analysis, which included our own results and those of one other study, substantiated the results of the trial. INTERPRETATION In women with a tubal pregnancy and a healthy contralateral tube, salpingotomy does not significantly improve fertility prospects compared with salpingectomy. FUNDING Netherlands Organisation for Health Research and Development (ZonMW), Region Västra Götaland Health & Medical Care Committee.


The New England Journal of Medicine | 2016

Randomized Trial of a Lifestyle Program in Obese Infertile Women

Meike Mutsaerts; Anne M. van Oers; Henk Groen; Jan M. Burggraaff; Walter K. H. Kuchenbecker; Denise A. M. Perquin; Carolien A. M. Koks; Ron van Golde; Eugenie M. Kaaijk; Jaap M. Schierbeek; G.J.E. Oosterhuis; Frank J. Broekmans; Wanda J. E. Bemelmans; Cornelis B. Lambalk; M.F.G. Verberg; Fulco van der Veen; Nicole F. Klijn; Patricia E.A.M. Mercelina; Yvonne M. van Kasteren; Annemiek W. Nap; Egbert A. Brinkhuis; Niels E. A. Vogel; Robert J. A. B. Mulder; Ed T. C. M. Gondrie; Jan Bruin; J. Marko Sikkema; Mathieu H.G. de Greef; Nancy C. W. ter Bogt; Jolande A. Land; Ben Willem J. Mol

BACKGROUND Small lifestyle-intervention studies suggest that modest weight loss increases the chance of conception and may improve perinatal outcomes, but large randomized, controlled trials are lacking. METHODS We randomly assigned infertile women with a body-mass index (the weight in kilograms divided by the square of the height in meters) of 29 or higher to a 6-month lifestyle intervention preceding treatment for infertility or to prompt treatment for infertility. The primary outcome was the vaginal birth of a healthy singleton at term within 24 months after randomization. RESULTS We assigned women who did not conceive naturally to one of two treatment strategies: 290 women were assigned to a 6-month lifestyle-intervention program preceding 18 months of infertility treatment (intervention group) and 287 were assigned to prompt infertility treatment for 24 months (control group). A total of 3 women withdrew consent, so 289 women in the intervention group and 285 women in the control group were included in the analysis. The discontinuation rate in the intervention group was 21.8%. In intention-to-treat analyses, the mean weight loss was 4.4 kg in the intervention group and 1.1 kg in the control group (P<0.001). The primary outcome occurred in 27.1% of the women in the intervention group and 35.2% of those in the control group (rate ratio in the intervention group, 0.77; 95% confidence interval, 0.60 to 0.99). CONCLUSIONS In obese infertile women, a lifestyle intervention preceding infertility treatment, as compared with prompt infertility treatment, did not result in higher rates of a vaginal birth of a healthy singleton at term within 24 months after randomization. (Funded by the Netherlands Organization for Health Research and Development; Netherlands Trial Register number, NTR1530.).


Fertility and Sterility | 1999

Adhesion of human endometrial fragments to peritoneum in vitro

Patrick G. Groothuis; Carolien A. M. Koks; Anton F.P.M. de Goeij; Gerard A.J. Dunselman; Jan Willem Arends; Johannes L.H. Evers

OBJECTIVE To evaluate the adhesion of endometrial fragments obtained during the proliferative phase of the menstrual cycle to fresh human peritoneum obtained during abdominal surgery. DESIGN A prospective, descriptive, morphologic and cell biologic study. SETTING Tertiary care university medical center. PATIENT(S) Six female volunteers. INTERVENTION(S) After endometrial biopsies performed during diagnostic laparoscopy, endometrial fragments were generated by enzymatic digestion and mechanical separation. Peritoneum was obtained during abdominal operations for benign indications. MAIN OUTCOME MEASURE(S) Adhesion of endometrial fragments was studied by histologic examination and scanning and transmission electron microscopy. RESULT(S) After incubation, the mesothelium was intact in some areas, whereas in other areas mesothelial cells were damaged or absent. Adhesion of endometrial fragments was observed only at locations where the basement membrane was exposed. In areas largely denuded of mesothelial cells, endometrial fragments spread over the basement membrane to form monolayers. CONCLUSION(S) Human peritoneum is suitable for studying the adhesion of endometrial fragments. Intact mesothelium prevents the adhesion of endometrial fragments, suggesting that trauma to the mesothelial lining is a prerequisite for endometrial cell adhesion.


BMC Women's Health | 2010

The LIFESTYLE study: costs and effects of a structured lifestyle program in overweight and obese subfertile women to reduce the need for fertility treatment and improve reproductive outcome. A randomised controlled trial

Meike Mutsaerts; Henk Groen; Nancy C. W. ter Bogt; Johanna H. T. Bolster; Jolande A. Land; Wanda J. E. Bemelmans; Walter K. H. Kuchenbecker; Peter G.A. Hompes; Nick S. Macklon; Ronald P. Stolk; Fulco van der Veen; J. W. M. Maas; Nicole F. Klijn; Eugenie M. Kaaijk; G.J.E. Oosterhuis; Peter X. J. M. Bouckaert; Jaap M. Schierbeek; Yvonne M. van Kasteren; Annemiek W. Nap; Frank J. Broekmans; Egbert A. Brinkhuis; Carolien A. M. Koks; Jan M. Burggraaff; Adrienne S. Blankhart; Denise A. M. Perquin; Marie H. Gerards; Robert J. A. B. Mulder; Ed T. C. M. Gondrie; Ben W. J. Mol; Annemieke Hoek

BackgroundIn the Netherlands, 30% of subfertile women are overweight or obese, and at present there is no agreement on fertility care for them. Data from observational and small intervention studies suggest that reduction of weight will increase the chances of conception, decrease pregnancy complications and improve perinatal outcome, but this has not been confirmed in randomised controlled trials. This study will assess the cost and effects of a six-months structured lifestyle program aiming at weight reduction followed by conventional fertility care (intervention group) as compared to conventional fertility care only (control group) in overweight and obese subfertile women. We hypothesize that the intervention will decrease the need for fertility treatment, diminish overweight-related pregnancy complications, and will improve perinatal outcome.Methods/DesignMulticenter randomised controlled trial in subfertile women (age 18-39 year) with a body mass index between 29 and 40 kg/m2. Exclusion criteria are azoospermia, use of donor semen, severe endometriosis, premature ovarian failure, endocrinopathies or pre-existent hypertensive disorders.In the intervention group the aim is a weight loss of at least 5% to10% in a six-month period, to be achieved by the combination of a diet, increase of physical activity and behavioural modification. After six months, in case no conception has been achieved, these patients will start fertility treatment according to the Dutch fertility guidelines. In the control group treatment will be started according to Dutch fertility guidelines, independently of the patients weight.Outcome measures and analysisThe primary outcome measure is a healthy singleton born after at least 37 weeks of gestation after vaginal delivery. Secondary outcome parameters including pregnancy outcome and complications, percentage of women needing fertility treatment, clinical and ongoing pregnancy rates, body weight, quality of life and costs.Data will be analysed according to the intention to treat principle, and cost-effectiveness analysis will be performed to compare the costs and health effects in the intervention and control group.DiscussionThe trial will provide evidence for costs and effects of a lifestyle intervention aiming at weight reduction in overweight and obese subfertile women and will offer guidance to clinicians for the treatment of these patients.Trial registrationDutch Trial Register NTR1530


Fertility and Sterility | 2008

Tubal perforation by Essure: three different clinical presentations

Josje Langenveld; Sebastiaan Veersema; Marlies Y. Bongers; Carolien A. M. Koks

OBJECTIVE To assess the convenience and safety of Essure sterilization in an outpatient setting and the use of ultrasound as diagnostic tool for verification of proper placement for the 3-month follow-up. DESIGN Prospective cohort study. SETTING Teaching hospital department of obstetrics and gynecology. PATIENT(S) Female patients with a request for permanent tubal sterilization. INTERVENTION(S) Essure sterilization. MAIN OUTCOME MEASURE(S) Bilateral tubal occlusion after Essure sterilization and complication rate. RESULT(S) A total of 149 patients were scheduled for Essure sterilization. Microinsert placement was attempted in 143 patients. Bilateral placement of the device was successful in 95% (95% confidence interval [CI] 92%-99%). Seven attempts were unsuccessful. The complication rate was 2% (n = 3), and all involved a perforation. These three cases are discussed in detail. Vaginal ultrasound was conclusive in 91.7% (95% CI 87%-96%); two perforations were not recognized on the ultrasound. CONCLUSION(S) Essure sterilization is a safe and reliable sterilization method in an outpatient setting. Perforation of the device is the most frequent complication. Vaginal ultrasound is reliable for verification after an uncomplicated procedure. When the procedure is difficult (e.g., higher resistance, more pain then average, more time or more than two devices needed), a hysterosalpingogram should be performed.


BMC Women's Health | 2012

The OPTIMIST study: optimisation of cost effectiveness through individualised FSH stimulation dosages for IVF treatment. A randomised controlled trial

Theodora C. van Tilborg; Marinus J.C. Eijkemans; Joop S.E. Laven; Carolien A. M. Koks; Jan Bruin; G.J. Scheffer; Ron van Golde; Kathrin Fleischer; Annemieke Hoek; Annemiek W. Nap; Walter K. H. Kuchenbecker; Petra A. P. Manger; Egbert A. Brinkhuis; Arne M. van Heusden; Alexander Sluijmer; Arie Verhoeff; Marcel van Hooff; Jaap Friederich; J.M.J. Smeenk; Janet Kwee; Harold R. Verhoeve; Cornelis B. Lambalk; Frans M. Helmerhorst; Fulco van der Veen; Ben Willem J. Mol; Helen L. Torrance; Frank J. Broekmans

BackgroundCosts of in vitro fertilisation (IVF) are high, which is partly due to the use of follicle stimulating hormone (FSH). FSH is usually administered in a standard dose. However, due to differences in ovarian reserve between women, ovarian response also differs with potential negative consequences on pregnancy rates. A Markov decision-analytic model showed that FSH dose individualisation according to ovarian reserve is likely to be cost-effective in women who are eligible for IVF. However, this has never been confirmed in a large randomised controlled trial (RCT). The aim of the present study is to assess whether an individualised FSH dose regime based on an ovarian reserve test (ORT) is more cost-effective than a standard dose regime.Methods/DesignMulticentre RCT in subfertile women indicated for a first IVF or intracytoplasmic sperm injection cycle, who are aged < 44 years, have a regular menstrual cycle and no major abnormalities at transvaginal sonography. Women with polycystic ovary syndrome, endocrine or metabolic abnormalities and women undergoing IVF with oocyte donation, will not be included. Ovarian reserve will be assessed by measuring the antral follicle count. Women with a predicted poor response or hyperresponse will be randomised for a standard versus an individualised FSH regime (150 IU/day, 225-450 IU/day and 100 IU/day, respectively). Participants will undergo a maximum of three stimulation cycles during maximally 18 months. The primary study outcome is the cumulative ongoing pregnancy rate resulting in live birth achieved within 18 months after randomisation. Secondary outcomes are parameters for ovarian response, multiple pregnancies, number of cycles needed per live birth, total IU of FSH per stimulation cycle, and costs. All data will be analysed according to the intention-to-treat principle. Cost-effectiveness analysis will be performed to assess whether the health and associated economic benefits of individualised treatment of subfertile women outweigh the additional costs of an ORT.DiscussionThe results of this study will be integrated into a decision model that compares cost-effectiveness of the three dose-adjustment strategies to a standard dose strategy. The study outcomes will provide scientific foundation for national and international guidelines.Trial registrationNTR2657


Gynecologic and Obstetric Investigation | 2000

Menstruum Induces Changes in Mesothelial Cell Morphology

Carolien A. M. Koks; Ayşe Y. Demir Weusten; Patrick G. Groothuis; Gerard A.J. Dunselman; Anton F.P.M. de Goeij; Johannes L.H. Evers

In previous studies, we have shown that menstrual endometrium preferentially adheres to the subepithelial lining of the peritoneum. It remains to be elucidated, however, whether this damage is preexisting or inflicted by the menstrual tissue itself. We hypothesized that the menstrual tissue itself damages the peritoneum. To investigate this, the viability of menstrual endometrial tissue in peritoneal fluid (PF) was evaluated and the morphologic changes in the mesothelial cells were studied by in vitro cocultures of menstruum with mesothelial cell monolayers. Menstruum was collected with a menstrual cup. Endometrial tissue was isolated from the menstruum, resuspended in culture medium or in the cell-free fraction of PF and cultured for 24, 48 or 72 h. A 3(4,5-dimethylthia-zolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to obtain a relative measure of viable adhered endometrial cells. Mesothelial cells isolated from human omental tissue were cultured on Matrigel or uncoated plastic. At confluence, overnight cocultures were performed and scanning electron microscopy was used to evaluate the morphologic changes. The viability of endometrial fragments was 84% (n = 36, p < 0.05), 82% (n = 27, not significant) and 104% (n = 14, not significant) when cultured in the cell-free fraction of PF for 24, 48 and 72 h, respectively, when compared to medium with 10% fetal calf serum. Menstrual endometrial fragments or menstrual serum added to and cocultured with mesothelial cells induced severe morphologic alterations of the latter, including retraction, shrinking and gap formation. Similar morphologic changes were observed when mesothelial cells were cocultured with menstrual endometrial fragments in PF or in culture inserts. Incubation with conditioned medium from cultured menstrual endometrium induced similar but less pronounced changes in morphology. In conclusion, menstrual endometrial fragments remain viable in PF in vitro for at least 72 h. Antegradely shed menstruum induces changes in mesothelial cell morphology, including retraction and shrinking with exposure of the underlying surface. These findings suggest that menstruum is harmful to the peritoneal lining. Therefore, by local destruction of the mesothelial layer, menstrual endometrium is able to create sites for adhesion.


Fertility and Sterility | 1997

Evaluation of a menstrual cup to collect shed endometrium for in vitro studies

Carolien A. M. Koks; Gerard A.J. Dunselman; Anton F.P.M. de Goeij; Jan Willem Arends; Johannes L.H. Evers

OBJECTIVE To evaluate whether a menstrual cup is a suitable instrument to collect antegradely shed endometrium for in vitro studies. DESIGN A prospective, descriptive, cell biological and immunohistochemical study. SETTING Tertiary care university medical center. PATIENT(S) Nine female volunteers with regular cycles. INTERVENTION(S) Menstrual effluent was collected with a menstrual cup. Experience with the menstrual cup was described. Cytospin specimens, frozen sections, and cultures were prepared from the obtained menstrual tissue. MAIN OUTCOME MEASURE(S) The acceptability of the menstrual cup. The presence and viability of endometrial tissue was evaluated using immunohistochemical staining and culture outcome. RESULT(S) All women except one described the menstrual cup as acceptable. Menstrual effluent contained single cells, clumps of cells, and glandlike structures. After 5 days of culture, the endometrial tissue appeared to be viable. Immunohistochemistry showed positive staining for vimentin in most cytospin specimens, in all cryostat specimens, and in 10 of 17 cultures. Cytokeratin 18 stained most cytospin specimens, all cryostat specimens, and 10 of 17 cultures. Positive staining for BW495/36 was observed in most cytospin specimens, all cryostat specimens, and 11 of 17 cultures. CONCLUSION A menstrual cup in an acceptable instrument to collect antegradely shed menstrual tissue. Menstruum contains viable endometrial tissue that can be used for in vitro studies of endometrium and endometriosis.

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Annemieke Hoek

University Medical Center Groningen

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Walter K. H. Kuchenbecker

University Medical Center Groningen

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Jackie Ross

University of Cambridge

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Kathrin Fleischer

Radboud University Nijmegen

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