Does size matter? A test of size-specific mortality in Atlantic salmon Salmo salar smolts tagged with acoustic transmitters.

Mortality rates of wild Atlantic salmon Salmo salar smolts implanted with acoustic transmitters were assessed to determine if mortality was size dependent. The routinely accepted, but widely debated, '2% transmitter mass: body mass' rule in biotelemetry was tested by extending the transmitter burden up to 12·7% of body mass in small [mean fork length (LF ) 138·3 mm, range 115-168 mm] downstream migrating S. salar smolts. Over the short timescale of emigration (range 11·9-44·5 days) through the lower river and estuary, mortality was not related to S. salar size, nor was a relationship found between mortality probability and transmitter mass: body mass or transmitter length: LF ratios. This study provides further evidence that smolt migration studies can deviate from the '2% rule' of thumb, to more appropriate study-specific measures, which enables the use of fishes representative of the body size in natural populations without undue effects.

Freshwater and coastal migration patterns in the silver-stage eel Anguilla anguilla.

The unimpeded downstream movement patterns and migration success of small female and male Anguilla anguilla through a catchment in north-west Europe were studied using an acoustic hydrophone array along the River Finn and into the Foyle Estuary in Ireland. Twenty silver-stage A. anguilla (total length, LT , range: 332-520 mm) were trapped 152 km upstream from a coastal marine sea-lough outlet and internally tagged with acoustic transmitters of which 19 initiated downstream migration. Migration speed was highly influenced by river flow within the freshwater (FW) compartment. Anguilla anguilla activity patterns were correlated with environmental influences; light, tidal direction and lunar phase all influenced the initiation of migration of tagged individuals. Migration speed varied significantly between upstream and lower river compartments. Individuals migrated at a slower speed in transitional water and sea-lough compartments compared with the FW compartment. While 88·5% survival was recorded during migration through the upper 121 km of the river and estuary, only 26% of A. anguilla which initiated downstream migration were detected at the outermost end of the acoustic array. Telemetry equipment functioned efficiently, including in the sea-lough, so this suggests high levels of mortality during sea-lough migration, or less likely, long-term sea-lough residence by silver A. anguilla emigrants. This has important implications for eel management plans.

Oxytocin is unequally distributed in a bag of normal saline--true or false?

Oxytocin infusion used in labour can sometimes be left hung on the stand for many hours. There has been no study to determine if oxytocin is equally distributed throughout the infusion bag and if the distribution stays the same with time. We postulated that there may be settling of the molecules such that oxytocin concentrates at the bottom of the infusion bag. Eight infusion bags were prepared by mixing 10 IU of oxytocin in 1 litre of normal saline. The infusion bags were hung on infusion stands for 8 hours after which 10 samples of 100 mls of the solution from each bag were taken in different containers and the concentration of oxytocin calculated using oxytocin specific Enzyme Immunoassay (EIA) in the different samples. No statistically significant correlation between the oxytocin concentration and the sample number was observed (p-value = 0.738). There was no obvious relationship between oxytocin concentration and the sample number in each bag. There was no evidence to suggest that a linear oxytocin concentration gradient develops in a bag of normal saline over an 8-hour period. In fact the distribution appears to be random and unequal.

Highly elevated atmospheric levels of volatile organic compounds in the Uintah Basin, Utah.

Oil and natural gas production in the Western United States has grown rapidly in recent years, and with this industrial expansion, growing environmental concerns have arisen regarding impacts on water supplies and air quality. Recent studies have revealed highly enhanced atmospheric levels of volatile organic compounds (VOCs) from primary emissions in regions of heavy oil and gas development and associated rapid photochemical production of ozone during winter. Here, we present surface and vertical profile observations of VOC from the Uintah Basin Winter Ozone Studies conducted in January-February of 2012 and 2013. These measurements identify highly elevated levels of atmospheric alkane hydrocarbons with enhanced rates of C2-C5 nonmethane hydrocarbon (NMHC) mean mole fractions during temperature inversion events in 2013 at 200-300 times above the regional and seasonal background. Elevated atmospheric NMHC mole fractions coincided with build-up of ambient 1-h ozone to levels exceeding 150 ppbv (parts per billion by volume). The total annual mass flux of C2-C7 VOC was estimated at 194 ± 56 × 10(6) kg yr(-1), equivalent to the annual VOC emissions of a fleet of ∼100 million automobiles. Total annual fugitive emission of the aromatic compounds benzene and toluene, considered air toxics, were estimated at 1.6 ± 0.4 × 10(6) and 2.0 ± 0.5 × 10(6) kg yr(-1), respectively. These observations reveal a strong causal link between oil and gas emissions, accumulation of air toxics, and significant production of ozone in the atmospheric surface layer.

An analysis of genetic stock identification on a small geographical scale using microsatellite markers, and its application in the management of a mixed-stock fishery for Atlantic salmon Salmo salar in Ireland.

A genetic stock identification (GSI) study was undertaken in a fishery for Atlantic salmon Salmo salar to determine the effects of restrictive fishery management measures on the stock composition of the fishery, and if accurate and precise stock composition estimates could be achieved on the small geographical scale where this fishery operates, using a suite of only seven microsatellite loci. The stock composition of the Foyle fishery was shown to comprise almost exclusively of Foyle origin fish in the 3 years after restrictive measures were introduced in 2007, compared to 85% the year before. This showed that the restrictive measures resulted in the Foyle fishery being transformed from a mixed-stock fishery to an almost exclusively single-stock fishery, and showed how GSI studies can guide and evaluate management decisions to successfully manage these fisheries. Highly accurate and precise stock composition estimates were achieved in this study, using both cBAYES and ONCOR genetic software packages. This suggests accurate and precise stock composition is possible even on small geographical scales.

Diagnostic and therapeutic dilemma associated with atypical glandular cells on liquid-based cervical cytology.

BACKGROUND: In 2008, the management of women in Ireland with atypical glandular cells changed to immediate referral to colposcopy. The optimal management of these women is unclear. A balance between the detection of occult disease and overtreatment is required. METHODS: Our study aim was to document the experience of this policy at the National Maternity Hospital, Dublin. Information from the computerized data management system was analysed with the statistical package SPSS. RESULTS: In 2009, 156 women attended colposcopy following a single atypical glandular cell diagnosis on liquid-based cytology. The mean age was 41 years. Thirty (19.2%) women had abnormal vaginal bleeding, 31 (19.9%) were smokers and 34 (21.8%) had received previous treatment. The colposcopy was satisfactory in 125 (80.1%) and unsatisfactory in 31 (19.9%). Cervical histology was available for 146 (93.6%) women: 57 excisional procedures and 89 diagnostic biopsies. Abnormal histology was detected in 46 women (31.5%). Four women (2.7%) had invasive cancer, five (3.4%) had adenocarcinoma in situ, 21 (14.4%) had cervical intraepithelial neoplasia (CIN) grade 2 or 3 and 16 (11.0%) had CIN1. No abnormality was detected in 100 women (68.5%), including 35 (61.4%) of those who had undergone excisional procedures. The colposcopic impression in this group was unsatisfactory in 10 women (28.6%), glandular abnormalities in six (17.1%), high- and low-grade changes in 12 (34.2%) and six (17.1%) women, respectively, and normal in one (2.9%). The findings were essentially negative in the remaining 10 women: overall, 30 (19.2%) of the 156 women referred to colposcopy had at least CIN2. CONCLUSION: This study confirmed significant levels of high-grade disease in women referred to colposcopy with atypical glandular cells on cytology. Concerns about undetected endocervical disease resulted in high levels of negative excisional biopsies. Alternative strategies, including endometrial sampling, human papillomavirus testing and discussion at clinicopathological meeting, should be considered.

Antepartum fetal heart rate monitoring: value of sound stimulation.

The fetal heart rate (FHR) response to sound stimulation has been studied. The normal fetus exhibits an acceleration of at least 15 beats/min sustained for at least 2 minutes. This response was studied in 116 pregnancies in which the fetus was considered to be at high risk. The response was impaired in the 3 cases of perinatal death, in 14 of 19 cases of perinatal morbidity, and in 17 of 27 fetuses whose subsequent birth weight was below the fifth percentile. An impaired response was of greater predictive value than the nonreactive pattern of nonstressed FHR monitoring.

Fetal breathing in labor.

Fetal breathing during labor was investigated in a 3-part study of 42 normal singleton pregnancies. In the first part fetal breathing movements (FBM) were compared antenatally and during labor in 22 patients to determine whether FBM persisted during labor in fetuses in whom these movements had been demonstrated antenatally. In the second part a double-blind trial was conducted on the responsiveness of fetal breathing in labor to maternal glucose infusion in 12 patients. In the third part the influence of artificial rupture of the membranes (ARM) to induce labor was examined in 8 patients. Fetuses spent 36% of their time making breathing movements antenatally but this decreased to less than 1% during labor. Fetal trunk movements also decreased during labor but not significantly. Fetal breathing and trunk movements were not stimulated by maternal glucose infusion. Fetal breathing but not trunk movements were significantly inhibited by ARM prior to the onset of labor. Cessation of fetal breathing in labor is normal, but the cause of this change in behavior has not been positively identified.

Fetal breathing movements and the diagnosis of labor: a prospective analysis of 100 cases.

One hundred patients self-admitted to the hospital with a diagnosis of labor, were observed for up to 45 minutes with real-time ultrasonography to determine if the presence or absence of fetal breathing movements was helpful in separating false labor from true labor. Fetal breathing movements were not detected in 31 patients, and 30 of these delivered spontaneously within 48 hours; fetal breathing movements were present in 69 cases, and pregnancy continued for at least 48 hours in 56; of the remaining 13, labor occurred spontaneously within 48 hours in eight, whereas five had labor induced. Assessment of the cervix by Bishop score after ultrasound further improved diagnostic precision; none of 13 patients with a score greater than 9 exhibited fetal breathing movements, and all delivered within 48 hours. Gestational age did not influence outcome; 25 patients were preterm, and all 22 in whom fetal breathing movements were present continued for more than 48 hours. The results suggest that the absence of fetal breathing movements differentiates true labor from false labor.

Ultrasound placental grading and amniotic fluid quantitation in prolonged pregnancy.

Serial ultrasound examinations were performed every three to five days to monitor 200 singleton pregnancies with gestations of 42 weeks or longer. Scanning was used to measure the deepest amniotic fluid pool and to grade placental echogenic changes. Oligohydramnios, defined as an amniotic fluid pool less than 30 mm, was detected in 33 patients (17%) and was an indication for intervention. Grade III placenta was found in 53 patients (27%), and no grade could be assigned in 13 (7%). Intrauterine growth retardation and meconium-stained or absent amniotic fluid at amniotomy occurred significantly more often in association with oligohydramnios than with grade III placenta, which was found before spontaneous labor in only 24% of cases. Ultrasound placental grading appears to offer little useful additional information to amniotic fluid quantitation in satisfactory monitoring of prolonged pregnancies.

Prolonged labor in nulliparas: lessons from the active management of labor.

OBJECTIVE: To define factors causing prolonged labor in nulliparous women undergoing active management of labor. METHODS: We included all nulliparas delivered during 1990-1994 with spontaneous onset of labor lasting more than 12 hours, singleton gestation, cephalic presentation, and labor at greater than 37 weeks. Each patient was matched with the next nulliparous woman who delivered with a labor lasting less than 12 hours and who fulfilled the same inclusion criteria. Subjects were managed according to the previously described active management of labor protocol from The National Maternity Hospital, Dublin. RESULTS: In the 5-year period, 9018 nulliparas met inclusion criteria, with 147 (1.6%) having prolonged labor. Prolonged labor was due to inefficient uterine action in 65%, persistent occipitoposterior position in 24%, and cephalopelvic disproportion in 11% of cases. Univariate analysis showed statistically significant (P < .05) differences in maternal body mass index, cervical dilation on admission, oxytocin use, epidural use, placement of epidural at less than 2 cm of dilation, and birth weight between these study groups. On multivariate conditional logistic regression analysis, the following were significant independent predictors for having a prolonged labor (odds ratios with 95% confidence intervals presented): 3.1 (1.3-7.3) for cervical dilation less than 2 cm on admission, 42.7 (7.5-242.0) for early epidural placement, 5.1 (1.9-13.7) for epidural placement at greater than or equal to 2 cm, and 10.2 (3.6-29.4) for birth weight greater than 4000 g. CONCLUSION: Less-advanced cervical dilation on admission and epidural use, especially when placed early, are strongly associated with prolonged labor.

The influence of birth weight on labor in nulliparas.

The purpose of this study was to examine the hypothesis that dystocia in nulliparas is directly related to birth weight. The study was confined to the first 1000 nulliparas delivered in 1988 who went into labor after 37 weeks' gestation with a single live fetus and cephalic presentation. The management of labor was standardized. As birth weight increased, there was an increase in the mean duration of labor and of the second stage of labor, in the incidence of oxytocin augmentation, and in the incidence of both cesarean and forceps delivery for dystocia. The direct relationship between birth weight and the mean duration of labor was independent of gestation and oxytocin augmentation. These findings suggest that birth weight is an important factor in the development of dystocia in nulliparas.

An overview of hydramnios.

Hydramnios, defined as a volume of amniotic fluid in excess of 2,000 mL, is frequently diagnosed in contemporary obstetric practice by ultrasound. A pocket of amniotic fluid in excess of 8 cm X 1 cm is a satisfactory upper limit of normal volume using ultrasound. The etiology of hydramnios is not clear cut, but there is a significant 20% association with fetal anomaly. Maternal complications are rare, while fetal complications are usually related to an underlying anomaly or preterm birth. There is no specific treatment for hydramnios apart from drainage, which should be performed if maternal symptoms are sufficiently distressing. Perinatal outcome is generally determined by gestation at delivery or fetal anomaly.

Hyponatraemia and non-electrolyte solutions in labouring primigravida.

We performed a prospective randomised study on one hundred primigravid women who required oxytocin to augment labour, comparing dextrose infusion with normal saline. After delivery, the 45 patients whose oxytocin was infused in dextrose had significantly lower serum sodium levels in both mother and baby compared to the 48 patients who had their oxytocin administered in normal saline. This was particularly evident in those cases where epidural analgesia was employed.

Fetal acidosis in labour: a prospective study on the effect of parity.

The effect of parity on intrapartum fetal scalp pH was investigated in 6466 patients in labour with a live fetus who were delivered in 1987. 350 (5.4%) required fetal scalp blood sampling for pH (FBS), 236 primigravidae (10.4%) and 114 multigravidae (2.7%) (P less than 0.001). Fetal acidosis (pH less than 7.20) was detected in 35 patients, 27 primigravidae (11.4%) and 8 multigravidae (7.0%) (P less than 0.001). The incidence of intrapartum acidosis in the 2275 primigravidae and the 4191 multigravidae was 1.2 and 0.2% respectively (P less than 0.001). The two deaths from birth asphyxia and three cases of neonatal seizures occurred in primigravidae. In primigravidae requiring FBS, fetal acidosis was not associated with the use of oxytocin or with increased duration of labour. Neonatal seizures were more common overall in primigravidae than in multigravidae and more common in patients requiring FBS than in those not requiring FBS (P less than 0.05). The higher incidence of FBS, fetal scalp acidosis and neonatal seizures in primigravidae has important implications for intrapartum fetal monitoring.

DES clinic--the first six months.

In October 1990 a DES (Diethylstilbestrol) clinic was established at the National Maternity Hospital, Dublin. We describe the results of the first six months of the clinic. During this time, 172 inquiries were received; 95 women were seen at the clinic, 16 were deemed to be DES--exposed and eight were classified as possibly DES exposed. Classical cervicovaginal signs of DES exposure were noted in 15 women, a further eight women showed cervical epithelial abnormalities at colposcopy, the history of in utero DES exposure was confirmed in eight cases. No cases of cervical intraepithelial neoplasia or vaginal clear-cell adenocarcinoma were detected. Pregnancy related problems possibly attributable to DES exposure were documented in six women.