bone collagen breakdown is increased in thyrotoxicosis, and in postmenopausal women taking sufficient T4 to suppress serum TSH. Similarly treated premenopausal women appear to be at lower risk.

BackgroundContrast-induced nephropathy is a common complication of contrast administration in patients with chronic kidney disease and diabetes. Its pathophysiology is not well understood; similarly the role of intravenous or oral acetylcysteine is unclear. Randomized controlled trials to date have been conducted without detailed knowledge of the effect of acetylcysteine on renal function. We are conducting a detailed mechanistic study of acetylcysteine on normal and impaired kidneys, both with and without contrast. This information would guide the choice of dose, route, and appropriate outcome measure for future clinical trials in patients with chronic kidney disease.Methods/DesignWe designed a 4-part study. We have set up randomised controlled cross-over studies to assess the effect of intravenous (50 mg/kg/hr for 2 hrs before contrast exposure, then 20 mg/kg/hr for 5 hrs) or oral acetylcysteine (1200 mg twice daily for 2 days, starting the day before contrast exposure) on renal function in normal and diseased kidneys, and normal kidneys exposed to contrast. We have also set up a parallel-group randomized controlled trial to assess the effect of intravenous or oral acetylcysteine on patients with chronic kidney disease stage III undergoing elective coronary angiography. The primary outcome is change in renal blood flow; secondary outcomes include change in glomerular filtration rate, tubular function, urinary proteins, and oxidative balance.DiscussionContrast-induced nephropathy represents a significant source of hospital morbidity and mortality. Over the last ten years, acetylcysteine has been administered prior to contrast to reduce the risk of contrast-induced nephropathy. Randomized controlled trials, however, have not reliably demonstrated renoprotection; a recent large randomized controlled trial assessing a dose of oral acetylcysteine selected without mechanistic insight did not reduce the incidence of contrast-induced nephropathy. Our study should reveal the mechanism of effect of acetylcysteine on renal function and identify an appropriate route for future dose response studies and in time randomized controlled trials.Trial registrationClinical Trials.gov: NCT00558142; EudraCT: 2006-003509-18.

Key content Transperineal ultrasound allows reproducible imaging of pelvic floor conditions that aids in the thorough assessment required to diagnose and treat urogynaecological conditions. Views that can be obtained include two‐dimensional (2D) sagittal views of the bladder neck, urethra and pelvic floor; 2D coronal views of the anal canal; and three‐dimensional (3D) or four‐dimensional (4D) views of the genital hiatus and anal canal. This allows assessment of the post‐void residual volumes, detrusor wall thickness and dynamic assessment of the urethral morphology. Ultrasonographic assessment enables accurate information about maternal birth trauma to be ascertained, including levator ani muscle avulsion and obstetric anal sphincter injury. Transperineal ultrasound can be used to identify and assess previously implanted vaginal mesh and midurethral slings. Learning objectives To understand the role of ultrasound in clinical urogynaecology practice, including the assessment of slings and meshes. To know the ultrasound probes, techniques and views used to image the pelvic floor and anal sphincters by transperineal ultrasound. To describe assessment of the lower urinary tract, pelvic organ prolapse and obstetric anal sphincter injury using ultrasound. Ethical issues Thorough assessment of the pelvic floor is mandatory against the background of technological advances in the investigation of pelvic floor dysfunction. As a common and major complication of childbirth, maternal birth trauma must be assessed fully to support primary and secondary prevention. Thorough assessment must underlie the use of mesh implants, and dealing with sling and mesh complications is enhanced by imaging.

Background. Vaginal pessaries are known to be an effective treatment modality for pelvic organ prolapse (POP). Pessaries form an important part of the physician's armamentarium in the treatment of POP, but currently many of the factors affecting their successful use are poorly understood. Objectives. To determine the association between pessary retention (PR) at 1 year, and functional pelvic floor morphology, i.e. levator hiatal distance and area, and levator avulsion. Methods. This retrospective study reviewed the records of 73 patients with symptomatic POP at a tertiary urogynaecological centre. This multi-ethnic cohort had previously been studied for pelvic-floor morphology, had had 4D transperineal pelvic-floor ultrasound, and had opted for a vaginal pessary as a treatment option. Results. Our population had a mean age of 59.4 (range 32-91) years, and mean body mass index of 29.4 (range 20-42) kg/m 2 , with a mean assessment of stage 3 in the Pelvic Organ Prolapse Quantifications System (POP-Q). The level of prolapse was found to be related to PR (p=0.077). We further explored this concept using symmetric measures of association (γ=-0.353), indicating that PR decreases with increasing prolapse severity. PR was also found to be inversely associated with prior pelvic reconstructive surgery (n=63; p=0.055; γ=-0.417). There was a strong correlation that failed, however, to achieve significance by a small margin (p=0.052) between hiatal distance on contraction and PR. Conclusion. This study found an inverse relationship between PR and hiatal distance on contraction, prior pelvic surgery and the severity of prolapse. This was a pilot study with a limited number of participants, and the authors plan a prospective study to further clarify the association between long-term PR and functional pelvic floor morphology.