Towards the biomechanical modelling of the behaviour of ex-vivo porcine perineal tissues.

The perineum is a layered soft tissue structure with mechanical properties that maintain the integrity of the pelvic floor. During childbirth, the perineum undergoes significant deformation that often results in tears of various degrees of severity. To better understand the mechanisms underlying perineal tears, it is crucial to consider the mechanical properties of the different tissues that make up the perineum. Unfortunately, there is a lack of data on the mechanical properties of the perineum in the literature. The objective of this study is to partly fill these gaps. Hence sow perineums were dissected and the five perineal tissues involved in tears were characterized by uniaxial tension tests: Skin, Vagina, External Anal Sphincter, Internal Anal Sphincter and Anal Mucosa. From our knowledge, this study is the first to investigate all these tissues and to design a testing protocol to characterize their material properties. Six material models were used to fit the experimental data and the correlation between experimental and predicted data was evaluated for comparison. As a result, even if the tissues are of different nature, the best correlation was obtained with the Yeoh and Martins material models for all tissues. Moreover, these preliminary results show the difference in stiffness between the tissues which indicates that they might have different roles in the structure. These obtained results will serve as a basis to design an improved experimental protocol for a more robust structural model of the porcine perineum that can be used for the human perineum to predict perineal tears.

Pelvic floor muscle length changes with breathing in males: A preliminary report.

The study aimed to identify whether pelvic floor muscles modulate length with breathing, and if any length changes induced by breathing relate to abdominal cavity displacement and intra-abdominal pressure. To investigate these relationships, displacement of pelvic landmarks that related to pelvic floor muscle length using transperineal ultrasound imaging, breath volume, intra-abdominal pressure, abdominal and ribcage displacement, and abdominal and anal sphincter muscle electromyography were measured during quiet breathing and breathing with increased dead-space in ten healthy men. Pelvic floor muscle landmark displacement modulated with ribcage motion during breathing. This relationship was stronger for: i) motion of the urethrovesical junction (puborectalis muscle length change) than the mid-urethra landmark (striated urethral sphincter muscle length change), and ii) dead-space breathing in standing than dead-space breathing in supine or quiet breathing in standing. In most (but not all) participants, the urethrovesical junction descended during inspiration and elevated during expiration. Striated urethral sphincter length changes during the respiratory cycle was independent of intra-abdominal pressure. In summary, breathing involves pelvic floor muscle length changes and is consistent with the role of these muscles during respiration to aid maintenance of continence, lung ventilation and/or provision of support to the abdominal cavity. Clinicians who train pelvic floor muscles need to be aware that length change of pelvic floor muscles is expected with breathing.

What improvements in levator ani motor function lead to improvement in stress urinary incontinence signs and symptoms in females?

INTRODUCTION AND HYPOTHESIS: The objectives were to determine whether levator ani muscle (LAM) motor function is associated with female stress urinary incontinence (SUI) severity, and whether changes in LAM motor function induced through pelvic floor muscle training (PFMT) are associated with improvements in SUI signs and symptoms. METHODS: Pelvic morphology and LAM function were evaluated using ultrasound imaging and manual palpation using the elements of the PERFECT Scheme (Power, Endurance, Repetitions, Fast contractions, Elevation, Co-contraction and Timing) before and after women with SUI underwent a 12-week PFMT intervention. SUI severity was determined subjectively (ICIQ-FLUTS-UI) and objectively (30-min pad test [30MPT]). RESULTS: At baseline (n = 97), less leakage on the 30MPT was weakly associated with higher bladder neck position (ρs = -0.209,p = 0.044), yet with lower LAM function based on the PERFECT Scheme (overall score: ρs = 0.206, p = 0.043; repeated maximum voluntary contractions (MVCs): ρs = 0.203, p = 0.046; power/motor control: ρs = 0.214, p = 0.035). Lower symptom severity (ICIQ-FLUTS-UI) was associated with observed perineal lift during coughing (U = 34.000; p = 0.042). All measures of SUI severity and LAM function were significantly improved after PFMT intervention. Greater improvements in bladder neck elevation during MVC (ρs = -0.261, p = 0.027) and greater reductions in levator plate length during MVC (ρs = 0.292, p = 0.016) were weakly associated with greater reductions in leakage (30MPT), the latter also being associated with more improvement symptoms (ICIQ-FLUTS-UI; ρs = 0.238, p = 0.041). Greater improvement in the ability to repeat MVCs (ρs = 0.303, p = 0.009) was weakly associated with smaller improvements in symptoms (ICIQ-FLUTS-UI). CONCLUSION: Improvements in bladder neck support and elevation show weak associations with improvement in SUI signs and symptoms. LAM function as measured by the PERFECT Scheme is not associated with SUI severity in women, and improvements in LAM function when measured by the PERFECT Scheme are not associated with improvements in SUI signs and symptoms.

Cutaneous inputs from perineal region facilitate spinal locomotor activity and modulate cutaneous reflexes from the foot in spinal cats.

It is well known that mechanically stimulating the perineal region potently facilitates hindlimb locomotion and weight support in mammals with a spinal transection (spinal mammals). However, how perineal stimulation mediates this excitatory effect is poorly understood. We evaluated the effect of mechanically stimulating (vibration or pinch) the perineal region on ipsilateral (9-14 ms onset) and contralateral (14-18 ms onset) short-latency cutaneous reflex responses evoked by electrically stimulating the superficial peroneal or distal tibial nerve in seven adult spinal cats where hindlimb movement was restrained. Cutaneous reflexes were evoked before, during, and after mechanical stimulation of the perineal region. We found that vibration or pinch of the perineal region effectively triggered rhythmic activity, ipsilateral and contralateral to nerve stimulation. When electrically stimulating nerves, adding perineal stimulation modulated rhythmic activity by decreasing cycle and burst durations and by increasing the amplitude of flexors and extensors. Perineal stimulation also disrupted the timing of the ipsilateral rhythm, which had been entrained by nerve stimulation. Mechanically stimulating the perineal region decreased ipsilateral and contralateral short-latency reflex responses evoked by cutaneous inputs, a phenomenon we observed in muscles crossing different joints and located in different limbs. The results suggest that the excitatory effect of perineal stimulation on locomotion and weight support is mediated by increasing the excitability of central pattern-generating circuitry and not by increasing excitatory inputs from cutaneous afferents of the foot. Our results are consistent with a state-dependent modulation of reflexes by spinal interneuronal circuits.

The Spinal Control of Backward Locomotion.

Animal locomotion requires changing direction, from forward to backward. Here, we tested the hypothesis that sensorimotor circuits within the spinal cord generate backward locomotion and adjust it to task demands. We collected kinematic and electromyography (EMG) data during forward and backward locomotion at different treadmill speeds before and after complete spinal transection in six adult cats (three males and three females). After spinal transection, five/six cats performed backward locomotion, which required tonic somatosensory input in the form of perineal stimulation. One spinal cat performed forward locomotion but not backward locomotion while two others stepped backward but not forward. Spatiotemporal adjustments to increasing speed were similar in intact and spinal cats during backward locomotion and strategies were similar to forward locomotion, with shorter cycle and stance durations and longer stride lengths. Patterns of muscle activations, including muscle synergies, were similar for forward and backward locomotion in spinal cats. Indeed, we identified five muscle synergies that were similar during forward and backward locomotion. Lastly, spinal cats also stepped backward on a split-belt treadmill, with the left and right hindlimbs stepping at different speeds. Therefore, our results show that spinal sensorimotor circuits generate backward locomotion but require additional excitability compared with forward locomotion. Similar strategies for speed modulation and similar patterns of muscle activations and muscle synergies during forward and backward locomotion are consistent with a shared spinal locomotor network, with sensory feedback from the limbs controlling the direction.SIGNIFICANCE STATEMENT Animal locomotion requires changing direction, including forward, sideways and backward. This paper shows that the center controlling locomotion within the spinal cord can produce a backward pattern when instructed by sensory signals from the limbs. However, the spinal locomotor network requires greater excitability to produce backward locomotion compared with forward locomotion. The paper also shows that the spinal network controlling locomotion in the forward direction also controls locomotion in the backward direction.

Metrics of perineal support (MOPS) study.

BACKGROUND: Manual perineal protection (MPP) is an intrapartum intervention suggested to protect perineal integrity during childbirth. Proper execution of MPP is complex and evaluation of its true contribution is difficult in the clinical setting because of the large number of obstetric variables, some of which are hardly quantifiable. In this study we aimed to gather initial data on the forces executed by the accoucheur's thumb, index and middle fingers during MPP at the time of fetal head expulsion, quantify the duration of the intervention and investigate the timely interaction of the different components of MPP. METHODS: Two bespoke right-handed measurement gloves (MG), with built in sensors, were designed and produced. The MG allowed the electronic real-time measurement of applied forces during MPP and transferred this data wirelessly to an integrated computer system. Sterile gloves were worn over the MG when used at the time of birth. The study was undertaken between January and December 2019. Singleton, term pregnant women having their first vaginal birth who provided a valid written consent were enrolled into this prospective pilot study. All deliveries were undertaken by one of two obstetricians experienced in MPP. RESULTS: Twenty women were enrolled. The mean duration of execution of MPP during the last contraction was 13.6 s. In 20% it lasted < 5 s. The overall mean values of the average and maximum forces of the thumb, index and middle fingers were 26.7 N; 25.5 N; 20.2 N and 34.3 N; 32.6 N; and 27.6 N respectively. The onset of fingers and thumb activity was simultaneous in 13 cases (65%), while in seven (35%) deliveries the middle finger's force activity was initiated later. CONCLUSIONS: MPP during fetal head expulsion happens over a short period of time. In the majority of cases the thumb and fingers actions started simultaneously. There were differences in the duration of application and the forces executed by the fingers and thumb between the two practitioners, however this was only significant for thumb measurements. The results obtained will aid in improving further MPP modeling studies to optimize the technique.

Lumbosacral ventral root avulsion alters reflex activation of bladder, urethra, and perineal muscles during micturition in female rabbits.

AIM: To determine the effect of the lumbosacral ventral root avulsion (VRA) on the reflex activation of bladder, urethra, and activation of perineal muscles during micturition in female rabbits. METHODS: We allocated 14 virgin female rabbits to evaluate, first, the gross anatomy of lumbosacral spinal cord root (n = 5) and, second, to determine the effect of VRA on perineal muscles during micturition (n = 9). We recorded cystometrograms, urethral pressure, and electromyograms of the bulbospongiosus (Bsm) and ischiocavernosus (Ism) muscles before and after the L6-S2 VRA. Standard variables were measured from each recording and analyzed to identify significant differences (P < .05). RESULTS: We found that the L6-S2 VRA affected directly the bladder and urethral function and reduced the duration and the frequency of the bursting of Ism and Bsm muscles during voiding. The Ism and Bsm showed a phasic activation, of different frequencies, during the voiding phase and the L6-S2 VRA inhibited the co-contraction of the Ism and Bsm-bladder-urethra. CONCLUSIONS: The Ism and Bsm are activated at different frequencies to trigger the voiding phase. The L6-S2 VRA affected the activity pattern of both perineal muscles. These modifications affected the bladder and urethra function. It is possible that the restoration of the activation frequency of perineal muscles contributed for an efficient bladder contraction.

Pulsed Radiofrequency of the Sacral Roots Improves the Success Rate of Superior Hypogastric Plexus Neurolysis in Controlling Pelvic and Perineal Cancer Pain.

BACKGROUND: Superior hypogastric plexus neurolytic (SHP-N) block is the mainstay management for pelvic cancer pain of visceral origin when oral opioids fail due to inefficacy or intolerance to side effects. Unfortunately, SHP-N has the potential to control pelvic pain in 62%-72% of patients at best, because chronic pelvic pain may assume additional characteristics other than visceral. OBJECTIVE: Combining SHP-N with pulsed radiofrequency (PRF) of the sacral roots might block most of the pain characteristics emanating from the pelvic structures and improve the success rate of SHP-N in controlling pelvic and perineal cancer pain. STUDY DESIGN: This study was a prospective randomized controlled clinical trial. SETTINGS: The research took place in the interventional pain unit of a tertiary center in the university hospital. METHODS: Fifty-eight patients complaining of cancer-related chronic pelvic and perineal pain were randomized to either the PRF + SHP group (n = 29), which received SHP-N combined with PRF of the sacral roots S2-4, or the SHP group (n = 29), which received SHP-N alone. The outcome variables were the percentage of patients who showed a > 50% reduction in their Visual Analog Scale (VAS) pain score, the VAS pain score, and global perceived effect evaluated during a 3-month follow-up period. RESULTS: The percentage of patients who showed a > 50% reduction in their VAS pain score was significantly higher in the SHP + PRF group compared to the SHP group when assessed at one month (92.9% [n = 26] vs 57.7% [n = 15]; P = .003) and 3 months (85.7% [n = 24) vs 53.8% [n = 14]; P = .01) post procedure, respectively. However, no significant difference was observed between the 2 groups at the 6-month evaluation (SHP + PRF [57.1% (n = 16)] vs SHP [50% (n = 13)]; P = .59). There was a statistically significant reduction of VAS in the SHP + PRF group in comparison to the SHP group at one month (2.8 ± 0.9 vs 3.5 ± 1.2 [mean difference, -0.7 (95% confidence interval [CI], -1.29 to -0.1), P = .01]), 2 months (2.8 ± 0.9 vs 3.5 ± 1.2 [mean difference, -0.64 (95% CI, -1.23 to -0.05), P = .03]), and 3 months (2.7 ± 1 vs 3.4 ± 1.2 [mean difference, -0.67 (95% CI, -1.29 to -0.05)], P = .03]) post procedure, respectively; however, the 2 groups did not significantly differ at 2 weeks, 4, 5, and 6 months post procedure. Regarding postprocedural analgesic consumption, there were trends towards reduced opioid consumption at all postprocedural measured time points in the SHP+PRF group compared to the SHP group; these differences reached statistical significance at 2 months (median, 30 [interquartile range (IQR), 0.00-30] vs median, 45 [IQR, 30-90]; P = .046) and 3 months (median, 0.00 [IQR, 0.00-30] vs median, 30 [IQR, 0.00-67.5]; P = .016) post procedure, respectively. LIMITATIONS: The study follow-up period is limited to 6 months only. CONCLUSIONS: SHP-N combined with PRF of the sacral roots (S2, 3, 4) provided a better analgesic effect than SHP-N alone for patients with chronic pelvic and perineal pain related to pelvic cancer. TRIAL REGISTRY: ClinicalTrials.gov. NCT03228316. KEY WORDS: Pelvic pain, pulsed radiofrequency, sacral roots, superior hypogastric plexus.

Adaptation of tape removal test for measurement of sensitivity in perineal area of rat.

Regeneration after spinal cord injury is a goal of many studies. Although the most obvious target is to recover motor function, restoration of sensation can also improve the quality of life after spinal cord injury. For many patients, recovery of sensation in the perineal and genital area is a high priority. Currently there is no experimental test in rodents for measuring changes in sensation in the perineal and genital area after spinal cord injury. The aim of our study was to develop a behavioural test for measuring the sensitivity of the perineal and genital area in rats. We have modified the tape removal test used routinely to test sensorimotor deficits after stroke and spinal cord injury to test the perineal area with several variations. A small piece of tape (approximately 1 cm2) was attached to the perineal area. Time to first contact and to the removal of the tape was measured. Each rat was trained for 5 consecutive days and then tested weekly. We compared different rat strains (Wistar, Sprague-Dawley, Long-Evans and Lewis), both genders, shaving and non-shaving and different types of tape. We found that the test was suitable for all tested strains, however, Lewis rats achieved the lowest contact times, but this difference was significant only for the first few days of learning the task. There were no significant differences between gender and different types of tape or shaving. After training the animals underwent dorsal column lesion at T10 and were tested at day 3, 8, 14 and 21. The test detected a sensory deficit, the average time across all animals to sense the stimulus increased from 1'32 up to 3'20. There was a strong relationship between lesion size and tape detection time, and only lesions that extended laterally to the dorsal root entry zone produced significant sensory deficits. Other standard behavioural tests (BBB, von Frey, ladder and Plantar test) were performed in the same animals. There was a correlation between lesion size and deficit for the ladder and BBB tests, but not for the von Frey and Plantar tests. We conclude that the tape removal test is suitable for testing perineal sensation in rats, can be used in different strains and is appropriate for monitoring changes in sensation after spinal cord injury.

The histological microstructure and in vitro mechanical properties of pregnant and postmenopausal ewe perineal body.

OBJECTIVE: The mechanical properties and microstructure of the perineal body are important for the improvement of numerical models of pelvic organs. We determined the mechanical parameters and volume fractions of the ewe perineal body as an animal model. METHODS: The 39 specimens of 13 pregnant swifter ewes delivering by cesarean section (aged 2 years, weight 61.2 ±â€Š6.2 kg (mean ±â€Šstandard deviation) and 24 specimens of 8 postmenopausal swifter ewes 150 days after surgical ovariectomy (aged 7 years, 58.6 ±â€Š4.6 kg)) were loaded uniaxially to determine Young's moduli of elasticity in the small (E0) and large (E1) deformation regions, and ultimate stresses and strains. The 63 adjacent tissue samples were processed histologically to assess volume fractions of smooth and skeletal muscle, adipose cells, elastin, and type I collagen using a stereological point testing grid. We compared the structural and mechanical differences along the ewe perineal body, and between pregnant and postmenopausal groups. RESULTS: The pregnant/postmenopausal perineal body was composed of smooth muscle (12/14%; median), skeletal muscle (12/16%), collagen (10/23%), elastin (8/7%), and adipose cells (6/6%). The E0 was 37/11 kPa (median), E1 was 0.97/1.04 MPa, ultimate stress was 0.55/0.59 MPa, and ultimate strain was 0.90/0.87 for pregnant/postmenopausal perineal body. The perineal body showed a structural and mechanical stability across the sites. The pregnant ewes had a higher amount of skeletal muscle, higher E0, and a less amount of collagen when compared with postmenopausal ewes. CONCLUSIONS: The data can be used as input for models simulating vaginal delivery, pelvic floor prolapsed, or dysfunction.

The histological microstructure and in vitro mechanical properties of the human female postmenopausal perineal body.

OBJECTIVE: The perineal body connects muscles from the pelvic floor and is critical for support of the lower part of the vagina and proper function of the anal canal. We determined mechanical parameters and volume fractions of main components of the human female postmenopausal perineal body. METHODS: The specimens were taken from 15 fresh female cadavers (age 74 ±â€Š10, mean ±â€Šstandard deviation). Seventy-five specimens from five regions of the perineal body were processed histologically to assess volume fractions of tissue components using stereological point testing grid. Fifteen specimens taken from the midline region were loaded uniaxially with 6 mm/min velocity until tissue rupture to determine Young's modulus of elasticity, ultimate stresses, and strains. RESULTS: The perineal body was composed of collagen (29%), adipose cells (27%), elastin (7%), smooth muscle (11%), and skeletal muscle (3%). The residual tissue (19%) constituted mostly peripheral nerves, lumina of blood vessels, fibroblasts, and fibrocytes. Young's modulus of elasticity at midline region was 18 kPa (median) at small and 232 kPa at large deformations, respectively. The ultimate stress was 172 kPa and the ultimate strain was 1.4. CONCLUSIONS: We determined the structural and mechanical parameters of the perineal body. The resultant data could be used as input for models simulating pelvic floor prolapse or dysfunction.

Effects of perineal preparation techniques on tissue extensibility and muscle strength: a pilot study.

INTRODUCTION AND HYPOTHESIS: Perineal preparation techniques for childbirth have been used with the aim of reducing perineal tears during the expulsive phase of labor. However, no studies were found to investigate the effects of instrument-assisted stretching versus perineal massage on pelvic floor muscle (PFM) variables. Therefore, the aim of this study was to evaluate the effect of instrument-assisted stretching versus perineal massage on the extensibility and strength of the PFMs. METHODS: Primiparous women were randomized to the instrument-assisted stretching (IStr) group (n = 13) and perineal massage (PnM) group (n = 14). The groups participated in eight sessions, twice weekly, beginning at the 34th gestational week. The IStr group underwent the intervention for 15 min using EPI-NO®. The PnM group underwent a perineal massage protocol for 10 min. Each woman was evaluated by a blinded physiotherapist before, after four and after eight sessions for primary (PFM extensibility using the EPI-NO® circumference) and secondary (PFM strength using a manometer) outcomes. Covariate analysis (ANCOVA) was used to compare the groups using the baseline values as a covariate. RESULTS: Both groups showed an increase in PFM extensibility compared with the evaluations before and after four and eight sessions (PnM group from 17.6 ± 1.8 to 20.2 ± 1.9 cm; IStr group from 19.9 ± 1.6 to 22.9 ± 1.6 cm;p < 0.001). There was no difference between groups. Regarding muscle strength, no statistical differences were observed between evaluations or between groups. CONCLUSIONS: Instrument-assisted stretching and perineal massage increase extensibility and do not alter the strength of PFMs in pregnant women.

[Evidence of sensory bladder inhibitor reflex]. / Démonstration neurophysiologique d'un réflexe périnéo-vésico-sensitif inhibiteur.

INTRODUCTION: Need to void level depends on two parameters, bladder volume and attentional process. If it is well known that the maximum voluntary contraction of the perineal muscles may transiently inhibit the micturition reflex itself, no work demonstrates the effect of this contraction on the intensity of the need itself. METHODS: An experimental, prospective, open, monocentric study was conducted between March and April 2017. In total, 15 subjects with no neurological history or neuro-perineal disorders consulting for functional constipation were included. Need to void level was evaluated by means of an electronic urgentometer. A control contraction of the dominant hand muscles was compared to a voluntary contraction of the external anal sphincter during a strong desire to void (B3). These contractions were recorded by means of surface electromyography. The main evaluation criterion was the comparison between the difference in visual analogic scale of the desire to void before (VAS-base) and after control voluntary contraction (VAS-hand) versus the same index (BAS-base then VAS-anal) after contraction of the external anal sphincter during a new B3. The comparison of maximum bladder capacities (MBC) measured after each record was the secondary endpoint. Wilcoxon signed rank test was used for statistical analysis. RESULTS: Voiding desire VAS decreased significantly (-13.14±12 vs -1.5±6; P=0.03) and MBC increased significantly (502.43±96.71mL vs 435.78±125.54mL; P=0.02) after anal compared to control contraction. CONCLUSION: This study suggests the existence of sensitive pathways inhibition by perineal contraction through a sensitive perineo-vesical inhibitory reflex. LEVEL OF EVIDENCE: 3.

An experiential model of education introduced to improve the confidence of student midwives in undertaking second stage management of the perineum (SSMP).

BACKGROUND AND OBJECTIVE: the limited availability of high quality evidence related to second stage management of the perineum (SSMP) combined with a perceived shift in UK practice towards a 'hands off' the perineum/fetal head approach are likely to have impacted significantly on student midwives' understanding of SSMP. This paper presents a classroom based educational session using low fidelity simulation, which was designed in response to student feedback and aimed to improve confidence in this skill. DESIGN: reflective teaching practice, based on evaluation of SSMP teaching. SETTING: an undergraduate midwifery programme based at an inner city university in London UK. PARTICIPANTS: student midwives. FINDINGS: the education session based on Kolb's experiential approach to learning appeared to address gaps in the previous teaching which was identified by students. The Classroom setting offered students a supportive setting in which to experiment with different SSMP approaches with a view to personalising care and without compromising safety. CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: although further longitudnal research is needed, the experiential model appears to offer a low resource approach to teaching SSMP and has potential application in other countries.

Multiparity modifies contractile properties of pelvic muscles affecting the genesis of vaginal pressure in rabbits.

AIMS: To characterize the contractile properties of the bulbospongiosus (Bsm), isquiocavernosus (Ism), and pubococcygeus muscles (Pcm), and their involvement in the genesis of vaginal pressure in nulliparous and multiparous rabbits. METHODS: Age-matched nulliparous and multiparous rabbits were used to record the isometric contractile responses of each muscle as well as the intravaginal pressure evoked by single square electrical pulses and stimulation trains of ascending frequency. To establish significant differences between groups, two-tail unpaired Student t tests were carried out. The linear correlation between intravaginal pressure and muscle contractile force was analyzed with Pearson correlation tests. For all cases, a P ≤ 0.05 was set as statistically significant. RESULTS: Multiparity decreased the contractile force of Bsm and Ism generated by high-frequency stimulation trains. The normalized force of the Pcm increased when evoked at 1, 4, and 10 Hz while this decreased at higher frequencies (20, 50, and 100 Hz). The contraction of both Bsm and Ism raised particularly the pressure on the perineal vagina while that of the Pcm increased the pressure in the pelvic vagina. Such a functional segregation is still present in multiparous rabbits albeit it was modified. CONCLUSIONS: Multiparity induces changes in the contractile responses of Bsm, Ism, and Pcm, which alterates the vaginal pressure.

Fetal head position and perineal distension associated with the use of the BD Odon Device™ in operative vaginal birth: a simulation study.

OBJECTIVE: To investigate (1) the placement of the BD Odon Device on the model fetal head and (2) perineal distention during simulated operative vaginal births conducted with the BD Odon Device. DESIGN: Observational simulation study. SETTING: North Bristol NHS Trust, UK. POPULATION OR SAMPLE: Four hundred and forty simulated operative vaginal births. METHODS: Three bespoke fetal mannequins were developed to represent (1) bi-parietal diameter of the 50th centile at term, (2) bi-parietal diameter at the 5th centile at term, and (3) 50th centile head with 2 cm of caput. Siting of the BD Odon Device on model heads was determined before and after 400 simulated operative vaginal births. Variables were analysed to determine their effect on device siting and movement during birth. The fetal mannequins were placed inside a maternal mannequin and the BD Odon Device was placed around the fetal head as per the instructions for use. The location of the air cuff was determined before and after the head was delivered. Perineal distension was determined by recording maximum perineal distention during a simulated operative vaginal birth using the same procedure, as well as scenarios employing an inappropriately non-deflated air cuff (for the BD Odon Device), the Kiwi ventouse and non-rotational forceps. MAIN OUTCOME MEASURES: Site and displacement during birth of the BD Odon Device on a model head. Maximal perineal distension during birth. RESULTS: The BD Odon Device was reliably sited in a standard over the fetal head position (approximately 40 mm above the fetal chin) for all stations, head sizes and positions with no significant displacement. In occipito-posterior births, compared with occipito-anterior or transverse, the BD Odon Device routinely sited further down the fetal head (toward the chin). The BD Odon Device was not associated with more perineal distension compared with forceps or Kiwi ventouse (respectively 21, 26 and 21 mm at posterior fourchette). CONCLUSIONS: The BD Odon Device reliably sited over a safe area of the fetal head in 400 simulated births representative of clinical practice. The BD Odon Device generates similar levels of perineal distension compared with Kiwi ventouse when used correctly. TWEETABLE ABSTRACT: Location of the BD Odon Device on a fetal head in simulation.

Pelvic floor muscle strength in primigravidae and non-pregnant nulliparous women: a comparative study.

INTRODUCTION AND HYPOTHESIS: The objective was to evaluate the pelvic floor muscles (PFM) in primigravidae and compare them with those in nonpregnant nulliparous women. METHODS: The sample consisted of 141 women with a mean age of 22.8 years, divided into four groups: 36 nonpregnant nulliparous (C), 31 primigravidae in the first trimester (1T), 42 primigravida in the second trimester (2T), and 32 primigravidae in the third trimester (3T). The participants were examined by digital palpation for pelvic floor muscle contraction using the Modified Oxford Scale, by measuring maximal vaginal squeeze pressure with a vaginal perineometer, and by measuring PFM maximal strength using a vaginal dynamometer. The best value of three maximal strengths was considered for analysis, the Kruskal-Wallis and Mann-Whitney U tests were used and differences were considered significant at p ≤ 0.05. RESULTS: The mean values for group C were 3.2 (digital palpation), 45.6 cmH2O (perineometry), and 11.7 N (dynamometry); for group 1T the corresponding values were 2.5, 21.1 cmH2O, and 8.8 N; for group 2T: 2.8, 22.9 cmH2O, and 7.8 N; and for group 3T: 2.1, 17.3 cmH2O, and 6.8 N. Groups were compared in pairs for digital palpation, perineometry, and dynamometry. There were significant differences between group C and group 1T, and between group C and group 3T. There was a significant difference between group C and group 2T with regard to perineometry and dynamometry, but not digital palpation. Dynamometry demonstrated a difference between groups 1T and 3T, digital palpation between groups 2T and 3T. CONCLUSION: Pelvic floor muscles in primigravidae are not as strong as those in nonpregnant nulliparous women.

Fiber type composition of pubococcygeus and bulbospongiosus striated muscles is modified by multiparity in the rabbit.

AIMS: We analyzed the effect of multiparity on the fiber type composition of two skeletal muscles involved in the maintenance of the micturition process, the pelvic pubococcygeus (Pc) and perineal bulbospongiosus (Bs) muscles in nulliparous and multiparous rabbits (Oryctolagus cuniculus). METHODS: We used the basic ATPase and NADH-TR techniques to identify and characterize slow, intermediate, and fast fiber types and glycolitic and oxidative fibers in muscles, respectively. RESULTS: Pc muscles of multiparous rabbits present relatively high percentages of slow and intermediate fibers but a low percentage of fast fibers (P < 0.05) as compared to Pc muscles from nulliparous rabbits, while percentages of glycolytic and oxidative fibers were similar (P > 0.05). Bs muscles of multiparous rabbits had a higher proportion of intermediate and glycolytic fibers (P < 0.05) than muscles of nulliparous. Both, Pc and Bs muscles of nulliparous and multiparous rabbits contain slow fibers with similar large cross sectional area, but fast fibers in multiparous muscles showed small cross sectional area than in nulliparous. CONCLUSIONS: Multiparity modified the fiber type composition of Pc and Bs muscles in female rabbits. We propose that the contractile force and the physiological role of both muscles during micturition are affected because of the observed changes in the relative composition of muscle fiber types.

Application of shear-wave elastography to estimate the stiffness of the male striated urethral sphincter during voluntary contractions.

OBJECTIVES: To investigate whether increases in stiffness can be detected in the anatomical region associated with the striated urethral sphincter (SUS) during voluntary activation using shear-wave elastography (SWE); to identify the location and area of the stiffness increase relative to the point of greatest dorsal displacement of the mid urethra (i.e. SUS); and to determine the relationship between muscle stiffness and contraction intensity. SUBJECTS AND METHODS: In all, 10 healthy men participated. A linear ultrasound (US) transducer was placed mid-sagittal on the perineum adjacent to a pair of electromyography electrodes that recorded non-specific pelvic floor muscle activity. Stiffness in the area expected to contain the SUS was estimated via US SWE at rest and during voluntary pelvic floor muscles contractions to 5%, 10% and 15% maximum. Still image frames were exported for each repetition and analysed with software that detected increases in stiffness above 150% of the resting stiffness. RESULTS: Pelvic floor muscle contraction elicited an increase in stiffness above threshold within the region expected to contain the SUS for all participants and contraction intensities. The mean (SD) ventral-dorsal distance between the centre of the stiffness area and region of maximal motion of the mid-urethra (caused by SUS contraction) was 5.6 (1.8), 6.2 (0.8), and 5.8 (0.7) mm for 5%, 10% and 15% maximal voluntary contraction, respectively. Greater pelvic floor muscle contraction intensity resulted in a concomitant increase in stiffness, which differed between contraction intensities (5% vs 10%, P < 0.001; 5% vs 15%, P < 0.001; 10% vs 15%, P = 0.003). CONCLUSION: Voluntary contraction of the pelvic floor muscles in men is associated with an area of stiffness increase measured with SWE, which concurs with the expected location of the SUS. The increase in stiffness occurred in association with an increase in perineal surface electromyography activity, providing evidence that stiffness amplitude relates to general pelvic floor muscle contraction intensity. Future applications of SWE may include investigations of patient populations in which dysfunction of the SUS is thought to play an important role, or investigation of the effect of rehabilitation programmes that target this muscle.

Behavior of perineum during delivery before fetal head expulsion.

INTRODUCTION AND HYPOTHESIS: The aim of this study was to describe perineum deformation during the final part of delivery and suggest a modification of the episiotomy cut to increase accuracy for obtaining a suitable angle (45°) for surgical wound suture. METHODS: This prospective study enrolled 45 primiparous women. The perineum at rest was marked with five lines (0°, 30°, 45°, 60°, 90°), and each line was marked with two dots (point A-B: to 2-3 cm from initial point in fourchette, respectively). Two digital pictures were taken: one with the women at rest and the second during fetal head crowning; displacements were calculated for each point and angle. RESULTS: When the perineum is distending, the initial point of every line in the posterior fourchette moves laterally in introitus (only the 0° line remains at midline). The angle and the distance to points A and B of each line drawn do not change significantly from at rest to crowning. However, comparing original line configuration with an imaginary line from the fourchette to points A and B before expulsion, the angle and the distance is increased statistically significantly. CONCLUSIONS: Perineal distension at the moment of fetal head crowning causes a linear displacement of the perineum, which causes the difference in angle between the incision and episiotomy suture. Therefore, to obtain an episiotomy suture from fourchette with an angle of 45°, theoretically, we would have several angle incision options (between 45° and 60°), with a less acute angle when the introitus cut is closer to the fourchette (45° to 6 mm and ∼60° in the fourchette) and a sharper angle with a longer episiotomy.