Evaluation of tissue depth, captive bolt penetration force and energy, and potential for bolt-thalamus contact in cadaver heads from physically castrated market barrows and immunocastrated boars.

The main objective of this study was to describe tissue thicknesses of cadaver heads from physically castrated market barrows (PC MARKET BARROWS) and immunocastrated boars (IC BOARS) at the frontal penetrating captive bolt (PCB) placement. Other objectives were to describe differences in bolt force and energy requirements to penetrate and describe potential for bolt-thalamus contact. Forty-four heads were obtained from PC MARKET BARROWS (n = 22) and IC BOARS (n = 22) of similar age and size that were rendered insensible with CO2. Mean HCW was 117.32 ±â€…3.52 kg. Snout to poll distance (cm) and maximum deflection distance (cm) were collected in duplicate. Heads were split at midline with a bandsaw and soft tissue and cranial thicknesses were measured with a digital caliper. Images of each cut surface were collected to evaluate the potential for thalamic damage. Tissue samples were retained from each half of each head and a universal tester was used to determine maximum force and energy of bolt penetration. There was no evidence to support a significant difference (P > 0.05) in tissue thicknesses between PC MARKET BARROWS and IC BOARS. Maximum deflection distance (maximum distance from a straight edge that was placed from the tip of the snout to the poll of the head) was not different (P = 0.10) between PC MARKET BARROWS (3.31 ±â€…0.10 cm) and IC BOARS (3.08 ±â€…0.10 cm). There was no evidence to support a difference (P = 0.77) in maximum force between PC MARKET BARROWS (7130.32 ±â€…483.23 N) and IC BOARS (6974.60 ±â€…463.70 N). There was also no evidence to support a difference (P = 0.62) in maximum energy between PC MARKET BARROWS (33.37 ±â€…2.77 J) and IC BOARS (32.04 ±â€…2.50 J). For PC MARKET BARROWS, there was a difference (P = 0.05) between the number of heads where the thalamus was located within the theoretical plane of bolt travel for market placement (21/21) versus mature placement (16/21). For IC BOARS, the number of heads where the thalamus was located within the plane of theoretical bolt path was not different between the two PCB placements (19/21 each). Overall, the data suggest that tissue profiles of PC MARKET BARROWS and IC BOARS do not differ at the frontal PCB placement site and the mechanical tools that are effective for PC MARKET BARROWS should also be effective for IC BOARS.

Fibroids and Fertility: A Comparison of Myomectomy and Uterine Artery Embolization on Fertility and Reproductive Outcomes.

Importance: Leiomyomata, or fibroids, are a common gynecological problem affecting many women of reproductive age. Historically, myomectomy is offered to women with symptomatic fibroids who desire to preserve fertility. More recently, uterine artery embolization (UAE) has been explored as another fertility-sparing option. Objective: This review aims to provide an in-depth summary of the effects on fertility and reproductive outcomes following myomectomy and UAE for the treatment of symptomatic fibroids. Evidence Acquisition: Articles were obtained from PubMed using search terms myomectomy, uterine artery embolization, and fertility, as well as American Society of Reproductive Medicine practice committee reports. References from identified sources were searched to allow for thorough review. Results: While myomectomy and UAE are both fertility-sparing options for women with fibroids, reproductive outcomes following myomectomy are superior to UAE with higher rates of clinical pregnancy and live births and lower rates of spontaneous abortion, abnormal placentation, preterm labor, and malpresentation. Conclusions: Myomectomy should be offered to women with symptomatic submucosal or cavity-distorting fibroids who have a strong desire for a future pregnancy. For women who are not appropriate surgical candidates, UAE can be offered, although detrimental effects on future fertility should be disclosed. Relevance: A thorough understanding of the efficacy of both myomectomy and UAE, as well as their impact on future fertility, allows for improved counseling when deciding the optimal intervention for women with fibroids who desire future fertility.

Quantification of cooling effects on basic tissue measurements and exposed cross-sectional brain area of cadaver heads from market pigs.

The objective of this project was to determine the impact of cooling on the soft tissue thickness, cranial thickness, and cross-sectional brain area of cadaver heads from market pigs. Documenting the effect of cooling on tissue dimensions of swine heads is valuable and important for future investigations of physical stunning and euthanasia methods that use cadaver heads. Scalded and dehaired cadaver heads with intact jowls were sourced from market pigs stunned with CO2 gas. After transport to the data collection location, a penetrating captive bolt (PCB) shot (Jarvis Model PAS-Type P 0.25R Caliber Captive Bolt Pistol with Medium Rod Assembly and Blue Powder Cartridges) was applied in the frontal position. Following PCB application, each head (n = 36) underwent an UNCHILLED treatment followed by CHILLED treatment. The UNCHILLED treatment involved images collected immediately after splitting each head along the bolt path, and the CHILLED treatment involved images of the same heads after storage in a walk-in cooler for 24 h at 2 to 4°C. All measurements for each treatment were collected from images of the heads on the plane of the bolt path immediately prior to and immediately after the refrigeration treatment. Measurements were performed by two observers. Across all measurements, mean interobserver coefficient of variation was 11.3 ± 0.6%. The soft tissue caudal to the bolt path was different (P = 0.0120) between treatments (CHILLED: 6.4 ± 0.2 mm; UNCHILLED: 7.2 ± 0.2 mm). The soft tissue thickness rostral to the bolt path was different (P = 0.0378) between treatments (CHILLED: 5.5 ± 0.2 mm; UNCHILLED: 6.1 ± 0.2 mm). Cranial thickness caudal to the bolt path was not different (P = 0.8659; CHILLED: 18.1 ± 0.6 mm; UNCHILLED: 18.3 ± 0.6 mm), nor was there a significant difference (P = 0.2593) in cranial thickness rostral to the bolt path between treatments (CHILLED: 16.2 ± 0.6 mm; UNCHILLED: 15.2 ± 0.6 mm). Cross-sectional brain area did not differ (P = 0.0737; CHILLED: 3633.4 ± 44.1 mm; UNCHILLED: 3519.9 ± 44.1 mm). A correction factor of 1.12 was determined from this study for cases where estimation of UNCHILLED soft tissue thickness from CHILLED soft tissue thickness is necessary.

A Retrospective observational cohort study of the effect of antenatal influenza vaccination on birth outcomes in Cape Town, South Africa, 2015-2016.

BACKGROUND: There are conflicting data concerning the impact of antenatal influenza vaccination on birth outcomes including low birthweight (LBW), preterm birth, small for gestational age (SGA), and stillbirth. METHODS: We conducted a retrospective observational cohort study of infants born to women residing in Mitchells Plain, Cape Town. Infants were born at 4 health facilities during May 28 - December 31, 2015 and April 15 - December 31, 2016. We performed crude and multivariable logistic regression, propensity score (PS) matching logistic regression, and inverse probability of treatment weighted (IPTW) regression to assess vaccine effectiveness (VE) against LBW, preterm birth, SGA, and stillbirth adjusting for measured confounders. RESULTS: Maternal vaccination status, antenatal history, and ≥1 birth outcome(s) were available for 4084/5333 (76.6%) pregnancies, 2109 (51.6%) vaccinated, and 1975 (48.4%) unvaccinated. The proportion LBW was lower in vaccinated (6.9%) vs. unvaccinated (12.5%) in multivariable [VE 0.27 (95% CI 0.07-0.42)], PS [VE 0.30 (95% CI 0.09-0.51)], and IPTW [VE 0.24 (95% CI 0.04-0.45)]. Preterm birth was less frequent in vaccinated (8.6%) than unvaccinated (16.4%) in multivariable [VE 0.26 (0.09-0.40)], PS [VE 0.25 (95% CI 0.09-0.41)], and IPTW [VE 0.34 (95% CI 0.18-0.51)]. The proportion SGA was lower in vaccinated (6.0%) than unvaccinated (8.8%) but not in adjusted models. There were few stillbirths in our study population, 30/4084 (0.7%). CONCLUSIONS: Using multiple analytic approaches, we found that influenza vaccination was associated with lower prevalence of LBW (24-30%) and preterm birth (25-34%) in Cape Town during 2015-2016.

Hormonal management of menopausal symptoms in women with a history of gynecologic malignancy.

OBJECTIVE: The aim of the study was to review the role of hormone therapy in menopausal patients with breast cancer and gynecologic malignancies. METHODS: We searched MEDLINE (via PubMed) using a combination of keywords and database-specific subject headings for the following concepts: menopause, hormone therapy, and cancer. Editorials, letters, case reports, and comments were excluded, as were non-English articles. Additional references were identified by hand-searching bibliographies of included articles. The searches yielded a total of 1,484 citations. All citations were imported into EndNote X9, where they were screened by the authors. RESULTS: In breast cancer survivors, systemic hormone therapy is not recommended, whereas local low-dose estrogen therapy may be considered after discussion with the patient's oncologist. Among endometrial cancer survivors, hormone therapy is considered safe in low-risk cancers but should be avoided in high-risk subtypes. For survivors of epithelial ovarian cancer and cervical cancer, hormone therapy can be considered, but should be avoided in women with estrogen-sensitive histologic subtypes. CONCLUSIONS: The risks of hormone therapy should be assessed on an individual basis, with consideration of age, type of hormone therapy, dose, duration of use, regimen, route, and prior exposure. Systemic hormone therapy is not recommended in breast cancer survivors, whereas vaginal low-dose estrogen appears safe. Hormone therapy may be used by endometrial, cervical, and ovarian cancer survivors with low-risk, non-estrogen-receptor-positive subtypes. Video Summary: http://links.lww.com/MENO/A516.

Acupuncture in Obstetrics and Gynecology.

IMPORTANCE: Acupuncture is a key component of therapy in traditional Chinese medicine. Only in the last few decades has acupuncture become popular in the United States. The mechanism behind acupuncture's effects on the body and brain has not been completely elucidated, but there is evidence that acupuncture has effects on the endocrine, immune, and sympathetic and parasympathetic nervous systems. It may also act through electrical and mechanical signaling through the connective tissue and fascia. Despite this uncertainty, the positive effects of acupuncture have been well established. OBJECTIVE: In this review, we discuss the basic concepts of traditional Chinese medicine and acupuncture and examine the evidence regarding the use of acupuncture in obstetrics and gynecology. EVIDENCE ACQUISITION: We conducted a literature review of acupuncture in obstetrics and gynecology using PubMed. RESULTS: The available data demonstrate that acupuncture is beneficial in the treatment of labor pain, back pain in pregnancy, and dysmenorrhea. It is unclear if acupuncture is effective for hyperemesis, chemotherapy-induced nausea and vomiting, and menopausal hot flushes, or if moxibustion is effective in correcting breech presentation. There are limited but positive data regarding menopause-related sleep disturbances, depression in pregnancy, and overactive bladder. Acupuncture is not beneficial for improving outcomes in in vitro fertilization. CONCLUSIONS AND RELEVANCE: Acupuncture is an increasingly popular therapy with many potential applications in obstetrics and gynecology. A general understanding of the basic principles of acupuncture and the safety and efficacy of its practice is necessary for the general obstetrician and gynecologist to make informed recommendations to patients.

Pharmacologic Treatment of Diabetes in Pregnancy.

IMPORTANCE: Diabetes affects 6% to 9% of pregnancies, with gestational diabetes mellitus accounting for more than 90% of cases. Pregestational and gestational diabetes are associated with significant maternal and fetal risks; therefore, screening and treatment during pregnancy are recommended. Recommendations regarding the preferred treatment of diabetes in pregnancy have recently changed, with slight differences between American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) recommendations. OBJECTIVE: Our review discusses the diagnosis, management, and treatment of pregestational and gestational diabetes with the oral hypoglycemic agents metformin and glyburide as well as insulin. We also review the evidence for the safety and efficacy of these medications in pregnancy. EVIDENCE ACQUISITION: Articles were obtained from PubMed, the ACOG Practice Bulletin on Gestational Diabetes Mellitus, and the SMFM statement on the pharmacological treatment of gestational diabetes. RESULTS: Insulin does not cross the placenta and has an established safety profile in pregnancy and is therefore considered a first-line treatment for gestational diabetes. Metformin and glyburide have also been shown to be relatively safe in pregnancy but with more limited long-term data. Regarding maternal and fetal outcomes, metformin is superior to glyburide and similar to insulin. CONCLUSIONS AND RELEVANCE: Insulin is the preferred pharmacologic treatment according to ACOG. However, SMFM has stated that outcomes with metformin are similar, and it may also be considered as first-line therapy. Both agree that the available data show that metformin is safer and superior to glyburide, and glyburide is no longer recommended as a first-line therapy for the treatment of gestational diabetes.

Relationship of captive bolt stunning location with basic tissue measurements and exposed cross-sectional brain area in cadaver heads from market pigs.

The objective of this study was to contrast the soft tissue thickness, cranial thickness, total tissue thickness, cross-sectional brain area, and bolt-brain contact from the common frontal application of captive bolt euthanasia with the alternative location behind the ear in cadaver swine heads. Twenty-three cadaver heads from pigs that were approximately 136 kg and 6 mo of age were collected from a regional slaughter establishment following CO2 stunning and assigned to either the FRONTAL (n = 11) or the CAUDAL TO PINNA (n = 12) application of the captive bolt. The soft tissue thickness was different (P < 0.0001) between the 2 applications (FRONTAL: 8.3 ± 3.4 mm; CAUDAL TO PINNA: 56.5 ± 3.4 mm). The cranial thickness was different (P < 0.0001) between the applications (FRONTAL: 23.4 ± 2.9 mm; CAUDAL TO PINNA: 26.5 ± 2.9 mm). There was also a difference (P < 0.0001) in the total tissue thickness between the 2 applications (FRONTAL: 31.7 ± 3.8 mm; CAUDAL TO PINNA: 73.4 ± 3.8 mm). Cross-sectional area was calculated from images collected immediately after the heads were cut along the plane of bolt travel by bandsaw and was different (P = 0.0028) between the 2 applications (FRONTAL: 25.2 ± 1.3 cm2; CAUDAL TO PINNA: 18.9 ± 1.3 cm2). Bolt-brain contact was also assessed from the images, and a difference (P = 0.0360) between the 2 applications (FRONTAL: 100 ± 10.5%; CAUDAL TO PINNA: 66.7 ± 10.5%) was identified. The results of this study suggest that the FRONTAL application may provide a bolt path with less tissue to travel through when compared with the CAUDAL TO PINNA application for pigs of the approximate age and weight of those in this study. Ultimately, the FRONTAL location may present less risk for the captive bolt euthanasia of swine at market weight at this time. Additional refinement of the CAUDAL TO PINNA procedure and modification to the captive bolt device to penetrate to a suitable depth to ensure brain damage is recommended.

Freezing of all embryos in in vitro fertilization is beneficial in high responders, but not intermediate and low responders: an analysis of 82,935 cycles from the Society for Assisted Reproductive Technology registry.

OBJECTIVE: To assess in vitro fertilization (IVF) and pregnancy outcomes in patients having their first frozen embryo transfer (FET) after a freeze-all cycle versus similar patients having their first fresh embryo transfer (ET). DESIGN: Retrospective cohort study. SETTING: None. PATIENT(S): Registry data on 82,935 patient cycles from the Society for Assisted Reproductive Technology (SART). INTERVENTION(S): All first fresh autologous IVF cycles were analyzed and compared to first FET cycles after a freeze-all first IVF stimulation. The cycles were subdivided into cohorts based upon the number of oocytes retrieved (OR): 1-5 (low), 6-14 (intermediate), and 15+ (high responders). Univariate analyses were performed on cycle characteristics, and multivariable regression analyses were performed on outcome data. MAIN OUTCOME MEASURE(S): Clinical pregnancy rate (CPR) and live-birth rate (LBR). RESULTS: Of the 82,935 cycles analyzed, 69,102 patients had their first fresh transfer, and 13,833 had a first FET. High responders were found to have a higher CPR and LBR in the FET cycles compared with the fresh ET cycles (61.5 vs. 57.4%; 52.0 vs. 48.9%). In intermediate responders, both CPR and LBR were higher after fresh ET compared with FET (49.6% vs. 44.2%; 41.2 vs. 35.3%). Similarly, in low responders, CPR and LBR were higher after fresh compared with FET (33.2% vs. 15.9%; 25.9% vs. 11.5%). CONCLUSION(S): A freeze-all strategy is beneficial in high responders but not in intermediate or low responders, thus refuting the idea that freeze-all cycles are preferable for all patients.

Radiologic Aspects of the Diagnosis of Pulmonary Embolism in Pregnancy.

Pulmonary embolism in pregnancy is a leading cause of maternal mortality. The clinical presentation is often nonspecific, making imaging essential for accurate diagnosis. After reviewing the literature on the radiologic diagnosis of pulmonary embolism in pregnancy, we concluded that both computed tomography pulmonary angiography and lung perfusion scintigraphy are sensitive with high positive predictive values in the presence of high clinical suspicion, but lung perfusion scintigraphy is recommended given lower maternal breast exposure to ionizing radiation and lower fetal contrast exposure. However, if a chest x-ray is abnormal, computed tomography pulmonary angiography is preferred due to high nondiagnostic rates of lung perfusion scintigraphy.

Risk Factors for Birth Defects.

IMPORTANCE: Major congenital abnormalities, or birth defects, carry significant medical, surgical, cosmetic, or lifestyle consequences. Such abnormalities may be syndromic, involving multiple organ systems, or can be isolated. Overall, 2% to 4% of live births involve congenital abnormalities. Risk factors for birth defects are categorized as modifiable and nonmodifiable. Modifiable risk factors require thorough patient education/counseling. The strongest risk factors, such as age, family history, and a previously affected child, are usually nonmodifiable. OBJECTIVE: This review focuses on risk factors for birth defects including alcohol consumption, illicit drug use, smoking, obesity, pregestational diabetes, maternal phenylketonuria, multiple gestation, advanced maternal age, advanced paternal age, family history/consanguinity, folic acid deficiency, medication exposure, and radiation exposure. EVIDENCE ACQUISITION: Literature review via PubMed. RESULTS: There is a strong link between alcohol use, folic acid deficiency, obesity, uncontrolled maternal diabetes mellitus, uncontrolled maternal phenylketonuria, and monozygotic twins and an increased risk of congenital anomalies. Advanced maternal age confers an increased risk of aneuploidy, as well as nonchromosomal abnormalities. Some medications, including angiotensin converting enzyme inhibitors, retinoic acid, folic acid antagonists, and certain anticonvulsants, are associated with various birth defects. However, there are few proven links between illicit drug use, smoking, advanced paternal age, radiation exposure, and statins with specific birth defects. CONCLUSIONS AND RELEVANCE: Birth defects are associated with multiple modifiable and nonmodifiable risk factors. Obstetrics providers should work with patients to minimize their risk of birth defects if modifiable risk factors are present and to appropriately counsel patients when nonmodifiable risk factors are present.

Ultrasound Examination of the Fetal Heart.

Congenital heart disease (CHD) occurs in 4-13 per 1000 births in the United States. While many risk factors for CHD have been identified, more than 90% of cases occur in low-risk patients. Guidelines for fetal cardiac screening during the second trimester anatomy ultrasound have been developed by the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) in order to improve antenatal detection rates and to standardize the fetal cardiac screening examination. Patients found to be at increased risk of CHD because of risk factors or an abnormal screening examination should be referred for second trimester fetal echocardiography. Recently, 3D and 4D ultrasound techniques are being utilized to enhance detection rates and to better characterize cardiac lesions, and several first trimester ultrasound screening markers have been proposed to identify patients at increased risk of CHD. However, detection rates have not improved significantly due to limitations such as cost, access, and training that are associated with new technologies and screening methods. The most cost effective way to improve detection rates of CHD may be to standardize screening protocols across practices according to established guidelines and to have a low threshold for referral for fetal echocardiography.

Surgical Management of Benign Adnexal Masses in the Pediatric/Adolescent Population: An 11-Year Review.

STUDY OBJECTIVE: The purpose of this study was to compare ovarian conservation rates and surgical approach in benign adnexal surgeries performed by surgeons vs gynecologists at a tertiary care institution. DESIGN: A retrospective cohort review. SETTING: Children's and adult tertiary care university-based hospital. PARTICIPANTS: Patients 21 years of age and younger who underwent surgery for an adnexal mass from January 2003 through December 2013. INTERVENTIONS: Patient age, demographic characteristics, menarchal status, clinical symptoms, radiologic imaging, timing of surgery, surgeon specialty, mode of surgery, rate of ovarian conservation, and pathology were recorded. Patients were excluded if they had a uterine anomaly or pathology-proven malignancy. MAIN OUTCOME MEASURES: The primary outcome was the rate of ovarian conservation relative to surgical specialty; secondary outcome was surgical approach relative to surgical specialty. RESULTS: Of 310 potential cases, 194 met inclusion criteria. Gynecologists were more likely than surgeons to conserve the ovary (80% vs 63%; odds ratio, 2.28; 95% confidence interval, 1.16-4.48). After adjusting for age, body mass index, mass size, and urgency of surgery, the difference was attenuated (adjusted odds ratio, 1.84; 95% confidence interval, 0.88-3.84). Surgeons and gynecologists performed minimally invasive surgery at similar rates (62% vs 50%; P = .11). A patient was more likely to receive surgery by a gynecologist if she was older (P < .001) and postmenarchal (P = .005). CONCLUSION: Results of our study suggest that gynecologists are more likely to perform ovarian-conserving surgery. However, our sample size precluded precise estimates in our multivariable model. Educational efforts among all pediatric and gynecologic surgeons should emphasize ovarian conservation and fertility preservation whenever possible.

Ciliated hepatic foregut cyst: a report of 6 cases and a review of the English literature.

BACKGROUND: Ciliated hepatic foregut cyst (CHFC) is a rare cystic lesion most commonly identified in segment 4 of the liver that arises from the embryonic foregut. The classic histologic pattern is comprised of 4 distinct layers (inner ciliated epithelial lining, smooth muscle, loose connective tissue, fibrous capsule). Although rare, cases of metaplastic and malignant epithelial lining have been described in CHFC. METHODS: We report 6 additional cases of CHFC, one of which had gastric metaplasia of the cyst lining, and review all reported cases of CHFC in the English literature. We describe the clinicopathologic analysis of 6 cases, with selective immunohistochemical analysis on 1 case with gastric metaplasia. RESULTS: Cases occurred in 4 women and 2 men (average age 55 years, range 42 to 67 years). Cysts ranged in size from 0.7 to 17 cm (average 7.2 cm) and were grossly tan-pink to white with blood-filled contents. The majority were located in segment 4 of the liver, however 2 were located in the porta hepatis. Tumor serologies (CA19-9 and/or CEA) were performed in 3 cases; 1 case demonstrated elevated CA19-9, and 2 cases had laboratory values within normal limits. All cases showed the classic histologic findings, however one case additionally had extensive gastric metaplasia. CONCLUSIONS: In conclusion, CHFC is a rare diagnostic entity that should be considered in the differential diagnosis for cystic hepatic lesions, particularly those located in segment 4 of the liver. Metaplasia and squamous carcinoma can occur, therefore complete surgical excision is the recommended treatment.

The impact of chorionicity on maternal pregnancy outcomes.

OBJECTIVE: Women carrying twin pregnancies often receive similar counseling, regardless of chorionicity, with the notable exception of twin-twin transfusion syndrome (TTTS); however, little is known about whether the presence of 1 vs 2 placentas confers dissimilar maternal risks. We sought to determine differences in maternal and neonatal outcomes based on chorionicity. STUDY DESIGN: This was a retrospective cohort study of all twin pregnancies at our institution undergoing routine second-trimester ultrasound for anatomic survey from 1990 through 2010. Secondary outcomes included other adverse maternal and neonatal outcomes. Relative risks and adjusted odds ratios (aORs) were calculated. Cluster analysis was used to account for nonindependence of twin pairs. RESULTS: Of 2301 pregnancies, 1747 (75.9%) were dichorionic and 554 (24.1%) were monochorionic. Rates of preeclampsia, gestational diabetes, placental abruption, placenta previa, preterm labor, and preterm premature rupture of membranes (PPROM) were not significantly different in dichorionic vs monochorionic pregnancies. Early preterm delivery less than 34 weeks (aOR, 1.47; 95% confidence interval [CI], 1.17-1.86) and less than 28 weeks (aOR, 2.58; 95% CI, 1.58-4.20) were more likely in monochorionic twins, as was neonatal intensive care unit admission (aOR, 1.41; 95% CI, 1.12-1.78). Monochorionic twins delivered earlier at a mean gestational age of 34.2 weeks vs 35.0 weeks for dichorionic twins (P < .001). Hospital length of stay was significantly longer for monochorionic twins with a mean of 13.7 days vs 10.8 days for dichorionic twins (P = .01). CONCLUSION: There are no significant differences in maternal outcomes by chorionicity; however, monochorionicity is associated with increased fetal risks. This information may be helpful in guiding more targeted counseling to expectant parents of twins that, although the presence of an additional placenta does not confer additional maternal risks, monochorionic infants tend to deliver earlier and require longer hospital stays.

Challenging research: completing participatory social research with children and adolescents in a hospital setting.

OBJECTIVE: A discussion of the challenges to completing participatory social research with children and adolescents in a hospital setting. BACKGROUND: Beginning with the dominant medical culture of hospitals, coupled with a persistent skepticism of social and in particular, qualitative research and its contribution to knowledge in medical circles, restrictive contextual challenges also include attitudinal, methodological, and logistical considerations. Together, these challenges hamper good participatory research practice and the capacity to maintain quality data, as well as impede children's participation in research, which has the capacity to contribute to healthcare design, policy, and planning processes. METHODS: Two studies in pediatric settings in Australia, one of which was completed in 2008 and the other which was discontinued in 2011, provide the basis for this research discussion. The discussion addresses the issues that persist in inhibiting the completion of participatory social research and the resulting impacts on research, children's right to participate, and the volume of evidence that is ultimately available from children's perspectives to support and inform healthcare design, planning, and policy in pediatric settings. CONCLUSIONS: Recommendations for changes that could strengthen and improve this research experience include building awareness of the potential value of this research; increasing its influence; building the capacity and knowledge of gatekeepers, ethics committees, and researchers working in this context; and recognizing and valuing children's competence and participation. KEYWORDS: Evidence-based design, hospital, methodology, patients, pediatric.

Use of multiple-locus variable-number tandem repeat analysis to evaluate Escherichia coli O157 subtype distribution and transmission dynamics following natural exposure on a closed beef feedlot facility.

To better understand the epizootiology of Escherichia coli O157:H7 among cattle, all E. coli O157 isolates recovered on a research feedlot during a single feeding period were characterized by multiple-locus variable-number tandem repeat analysis (MLVA). Three distinct MLVA subtypes (A, B, C), accounting for 24%, 15%, and 64% of total isolates, respectively, were identified. Subtypes A and B were isolated at the initiation of sampling, but their prevalence waned and subtype C, first isolated on the third sampling date, became the predominant subtype on the feedlot. Supershedding events, however, occurred with equal frequency for all three MLVA-types. Using a multilevel logistic regression model, we investigated whether the odds of shedding subtype C relative to subtypes A or B were associated with time, diet, or the presence of a penmate shedding high numbers of subtype C. Only time and exposure to an animal shedding MLVA-type C at 10³ colony-forming units or greater in the pen at the time of sampling were significantly associated with increased shedding of subtype C. High-level shedding of those E. coli O157 subtypes better suited for survival in the environment and/or in the host appear to play a significant role in the development of predominant E. coli O157 subtypes. Supershedding events alone are neither required nor sufficient to drive the epidemiology of specific E. coli O157 subtypes. Additional factors are necessary to direct successful on-farm transmission of E. coli O157.