Pelvic floor changes in the first term pregnancy and postpartum period.

OBJECTIVE: To follow a prospective cohort of women during their first term pregnancy to elucidate the nature and timing of changes to the pelvic floor during pregnancy and after vaginal delivery. METHODS: Enrolled subjects were evaluated at four time points with dynamic MRI, POP-Q examinations, and validated symptom questionnaires. The four assessments occurred during the first trimester (ePG), late third trimester (lPG), within a week after vaginal delivery (ePP), and three months postpartum (lPP). Two-dimensional T1-weighted MRI measurements included bladder descent and area of the levator hiatus at rest and during Valsalva maneuvers. Sample size of ten subjects was calculated for a power of 0.8 to detect a 20% change in bladder position with p < 0.05. Comparative statistical tests were used for parametric and non-parametric data, respectively. RESULTS: Twelve subjects completed the study. At lPP, the bladder descent was increased (p = 0.03) at rest and with Valsalva compared to ePG. Levator hiatus area did not differ (p = 0.63) between time points at rest or with Valsalva. Median POP stage increased (p = 0.001) to 1.5 at lPP. Mean genital hiatus increased (p = 0.0003) at each time point. Higher scores were recorded on the UDI-6 (p < 0.001) and the PFDI-20 (p = 0.003) questionnaires at lPG and ePP, but returned to ePG levels by lPP. CONCLUSION: Anatomic changes measured by dynamic MRI and POP-Q examinations demonstrate significant descent at 3 months postpartum. However, these anatomic changes did not significantly correlate with changes in symptoms.

Randomized trial of cesarean vs vaginal delivery for effects on the pelvic floor in squirrel monkeys.

BACKGROUND: Vaginal delivery is a risk factor in pelvic floor disorders. We previously described changes in the pelvic floor associated with pregnancy and parturition in the squirrel monkey, a species with a humanlike pattern of spontaneous age- and parity-associated pelvic organ prolapse. OBJECTIVE: The potential to prevent or diminish these changes with scheduled cesarean delivery (CD) has not been evaluated. In a randomized, controlled trial, we compared female squirrel monkeys undergoing spontaneous vaginal delivery with those undergoing scheduled primary CD for pelvic floor muscle volumes, muscle contrast changes, and dynamic effects on bladder neck position. STUDY DESIGN: Levator ani, obturator internus, and coccygeus (COC) muscle volumes and contrast uptake were assessed by magnetic resonance imaging in 20 nulliparous females examined prior to pregnancy, a few days after delivery, and 3 months postpartum. The position of bladder neck relative to bony reference line also was assessed with abdominal pressure using dynamic magnetic resonance imaging. RESULTS: Baseline measurements of 10 females randomly assigned to scheduled primary CD were not different from those of 10 females assigned to spontaneous vaginal delivery. Levator ani and obturator internus muscle volumes did not differ between groups, while volumes were reduced (P < .05) in the observation immediately after pregnancy. The COC muscles increased (P < .05) immediately after delivery for females in the spontaneous vaginal delivery group, but not for females in the scheduled CD group. Position of the bladder neck descended (P < .05) by 3 months postpartum in both groups. CONCLUSION: Scheduled CD diminishes changes in COC muscle volume and contrast reported to be associated with spontaneous vaginal delivery in squirrel monkeys. However, pelvic support of the bladder was not protected by this intervention suggesting that effects of pregnancy and delivery are not uniformly prevented by this procedure.

Lack of association between pelvic outlet diameter and pelvic organ prolapse in squirrel monkeys.

INTRODUCTION AND HYPOTHESIS: The aim was to test the hypothesis that the pelvic outlet diameter (POD) is associated with pelvic organ prolapse (POP) in squirrel monkeys. METHODS: Magnetic resonance images (MRI) were obtained from 55 females with and without POP. Commercial software was used by two observers to measure the POD. POD, age, parity, and weight for the two groups were compared using Student's t test. Associations of age, parity, and body weight with POD were evaluated with linear regression analysis. Multiple regression analysis examined the relationships of age, parity, and POD with POP. Receiver operating curve methods were used to set thresholds. RESULTS: Observers concurred on measurements (Cronbach's alpha = 0.96 with lower 95% confidence limit of 0.94). POD was not related to parity (p = 0.10) or weight (p = 0.053), but was inversely related to age (p = 0.011). Animals with POP did not differ from those without POP with regard to age (p = 0.10), weight (p = 0.17), or POD (p = 0.99). The groups differed with regard to parity (p = 0.007) and multiple regression methods demonstrated that only parity had a significant relationship with POP (p = 0.002). Parity greater than 2 had 64% specificity and 89% sensitivity for POP. CONCLUSIONS: POD size does not contribute to POP in squirrel monkeys. This study confirms that among variables of age, body weight, POD, and parity, only parity appears as a risk factor for POP in squirrel monkeys.

Alterations in pelvic floor muscles and pelvic organ support by pregnancy and vaginal delivery in squirrel monkeys.

INTRODUCTION AND HYPOTHESIS: The objective of this study was to measure the effects of pregnancy and parturition on pelvic floor muscles and pelvic organ support. METHODS: Levator ani, obturator internus, and coccygeus (COC) muscle volumes and contrast uptake were assessed by MRI of seven females prior to pregnancy, 3 days, and 4 months postpartum. Bladder neck and cervix position were measured dynamically with abdominal squeezing. RESULTS: The sides of three paired muscles were similar (p > 0.66). COC volumes were greater (p < 0.004) after parturition than before pregnancy or after recovery. COC contrast uptake increased (p < 0.02) immediately after delivery. Bladder neck position both in the relaxed state and abdominal pressure descended (p < 0.04) after delivery and descended further (p < 0.001) after recovery. Cervical position in the relaxed state before delivery was higher (p < 0.001) than postpartum but was unchanged (p = 0.50) with abdominal pressure relative to delivery. CONCLUSION: In squirrel monkeys, coccygeus muscles demonstrate the greatest change related to parturition, and parturition-related bladder neck descent seems permanent.

MR angiography of the renal arteries: intraindividual comparison of double-dose contrast enhancement at 1.5 T with standard dose at 3 T.

OBJECTIVE: The purpose of this study was to compare prospectively and within subjects use of 0.1 mmol/kg of gadodiamide at 3 T with use of 0.2 mmol/kg of gadodiamide at 1.5 T for MR angiography of the renal arteries. SUBJECTS AND METHODS: Twenty-two patients (14 men, eight women; mean age, 66.5 years) underwent two MR angiographic examinations of the renal arteries separated by at least 24 hours on whole-body 1.5- and 3-T MRI systems with a phase-encoded 3D spoiled breath-hold pulse sequence. Two radiologists blinded to the dose of contrast material assessed all image data in consensus for renal arterial disease and for image quality on a five-point Likert-type scale. Quantitative evaluation (vessel signal-to-noise ratio and vessel-muscle contrast-to-noise ratio) was performed by a third radiologist. RESULTS: Five renal arterial stenoses were detected with both techniques. The difference in mean image quality for the two doses and field strengths was not statistically significant. Overall vessel length and intraparenchymal branches, however, were better visualized with the double dose at 1.5 T. Signal-to-noise and contrast-to-noise ratios were significantly higher (both, p < 0.05) with the double dose at 1.5 T (125.7 and 64.2, respectively) compared with the standard dose at 3 T (112.3 and 59.7). CONCLUSION: MR angiography can be performed with high diagnostic image quality at 3 T with 0.1 mmol/kg of gadodiamide. Signal-to-noise and contrast-to-noise ratios are higher with a double dose at 1.5 T.

Renal arteries: comparison of steady-state free precession MR angiography and contrast-enhanced MR angiography.

All participants provided informed consent to participate in this study, which was approved by the institutional review board. Breath-hold three-dimensional (3D) steady-state free precession (SSFP) magnetic resonance (MR) angiography was compared with 3D contrast material-enhanced MR angiography in patients suspected of having renal artery stenosis. Two radiologists assessed visualization of renal arteries and detection of vascular disease. With SSFP MR angiography, 39 of 41 renal arteries in 19 patients were correctly detected. Relevant stenoses were correctly identified with SSFP MR angiography in two patients. In two patients, SSFP MR angiographic data sets led to false-positive overgrading of vascular disease. Fast breath-hold 3D SSFP MR angiography appears to be feasible for MR angiography of renal arteries.