Gestational length assignment based on last menstrual period, first trimester crown-rump length, ovulation, and implantation timing

PURPOSE

Understanding the natural length of human pregnancy is central to clinical care. However, variability in the reference methods to assign gestational age (GA) confound our understanding of pregnancy length. Assignation from ultrasound measurement of fetal crown-rump length (CRL) has superseded that based on last menstrual period (LMP). Our aim was to estimate gestational length based on LMP, ultrasound CRL, and implantation that were known, compared to pregnancy duration assigned by day of ovulation.

METHODS

Prospective study in 143 women trying to conceive. In 71 ongoing pregnancies, gestational length was estimated from LMP, CRL at 10-14 weeks, ovulation, and implantation day. For each method of GA assignment, the distribution in observed gestational length was derived and both agreement and correlation between the methods determined.

RESULTS

Median ovulation and implantation days were 16 and 27, respectively. The gestational length based on LMP, CRL, implantation, and ovulation was similar: 279, 278, 276.5 and 276.5 days, respectively. The distributions for observed gestational length were widest where GA was assigned from CRL and LMP and narrowest when assigned from implantation and ovulation day. The strongest correlation for gestational length assessment was between ovulation and implantation (r = 0.98) and weakest between CRL and LMP (r = 0.88).

CONCLUSIONS

The most accurate method of predicting gestational length is ovulation day, and this agrees closely with implantation day. Prediction of gestational length from CRL and known LMP are both inferior to ovulation and implantation day. This information could have important implications on the routine assignment of gestational age.

Early onset fetal growth restriction

Fetal growth restriction remains a challenging entity with significant variations in clinical practice around the world. The different etiopathogenesis of early and late fetal growth restriction with their distinct progression of fetal severity and outcomes, compounded by doctors and patient anxiety adds to the quandary involving its management. This review summarises the literature around diagnosing and monitoring early onset fetal growth restriction (early onset FGR) with special emphasis on optimal timing of delivery as guided by recent research advances.

A protein-truncating R179X variant in RNF186 confers protection against ulcerative colitis

Protein-truncating variants protective against human disease provide in vivo validation of therapeutic targets. Here we used targeted sequencing to conduct a search for protein-truncating variants conferring protection against inflammatory bowel disease exploiting knowledge of common variants associated with the same disease. Through replication genotyping and imputation we found that a predicted protein-truncating variant (rs36095412, p.R179X, genotyped in 11,148 ulcerative colitis patients and 295,446 controls, MAF=up to 0.78%) in RNF186, a single-exon ring finger E3 ligase with strong colonic expression, protects against ulcerative colitis (overall P=6.89 × 10(-7), odds ratio=0.30). We further demonstrate that the truncated protein exhibits reduced expression and altered subcellular localization, suggesting the protective mechanism may reside in the loss of an interaction or function via mislocalization and/or loss of an essential transmembrane domain.

Impact of cerebral redistribution on neurodevelopmental outcome in small-for-gestational-age or growth-restricted babies: a systematic review

OBJECTIVES

To review systematically the evidence on impact of cerebral redistribution, as assessed by fetal middle cerebral artery (MCA) Doppler, on neurological outcomes in small-for-gestational-age (SGA) or growth-restricted fetuses.

METHODS

For this systematic review, MEDLINE was searched for all controlled studies reporting neurological outcomes in SGA or growth-restricted babies with cerebral redistribution based on MCA Doppler indices, from inception to September 2013. We used relative risk or odds ratios, with 95% CI, to identify the association of cerebral redistribution with neurological outcomes.

RESULTS

The search yielded 1180 possible citations, of which nine studies were included in the review, with a total of 1198 fetuses. Definitions of SGA and cerebral redistribution were variable, as was study quality. Data could not be synthesized in meta-analyses because of heterogeneity in outcome reporting. Cerebral redistribution was not associated with increased risk of intraventricular hemorrhage in neonates (five studies; n = 806). When present in preterm fetuses, cerebral redistribution was associated with normal Neonatal Behavioral Assessment Scale (NBAS) scores at 40 weeks (one study; n = 62) but abnormal psychomotor development at 1 year of age on the Bayley scale (one study; n = 172). When present in term SGA fetuses, cerebral redistribution was associated with increased risk of motor and state organizational problems on NBAS (two studies; n = 158), and lower mean percentile scores in communication and problem solving at 2 years of age on the Ages and Stages Questionnaire (one study; n = 125).

CONCLUSIONS

SGA fetuses with cerebral redistribution may be at higher risk of neurodevelopmental problems. More data are needed from adequately controlled studies with long-term follow-up before conclusions can be drawn. If these findings are true, there is a need to re-evaluate timing of delivery in the management of SGA fetuses, particularly when cerebral redistribution is found at term gestation.

Survey of current practice in clinical transvaginal ultrasound scanning in the UK

During transvaginal ultrasound scanning, the fetus and other sensitive tissues are placed close to the transducer. Heating of these tissues occurs by direct conduction from the transducer and by absorption of ultrasound in the tissue. The extent of any heating will depend on the equipment and settings used, the duration of the scan, imaging modes and other aspects of scanning practice. To ensure that scans are performed with minimum risk, staff should have an appropriate knowledge of safety and follow guidelines issued by professional bodies. An online survey aiming to document current practice in transvaginal ultrasound in the UK was created and distributed to individuals performing this type of scanning. The survey posed questions about the respondents, the departments where scans were performed, the equipment used, knowledge of ultrasound safety, scanning practice and the frequency, duration and mode of transvaginal ultrasound scans for gynaecology, obstetrics and fertility applications. In all, 294 responses were obtained, mostly from sonographers (94%). From the analysis of the responses, it was clear that there was a good understanding of the general meaning of thermal and mechanical index and high awareness of guidelines issued by professional bodies. However, 40% of respondents stated that they rarely or never monitor Thermal or Mechanical indices during scanning. Scanning practice was consistent in terms of the duration of scans, scan protocols followed and use of imaging modes. The results highlight the importance of continued ultrasound safety training and promotion of safety guidelines to users.