Influence of compression of the inferior vena cava in the late second trimester on uterine and umbilical artery blood flow

Gastric emptying in pregnancy and its clinical implications: a narrative review

Delayed gastric emptying increases the risk of pulmonary aspiration during anaesthesia for Caesarean delivery. Our aim in conducting this narrative review was to consider the effect of pregnancy on gastric emptying. The indices of gastric emptying after liquids, solids, or both and when fasted in the various trimesters of pregnancy, at the time of Caesarean delivery, in labour, and the postpartum period were assessed. We considered 32 observational studies, one nonrandomised controlled study, and 22 randomised controlled trials. The evidence indicates that, compared with the nonpregnant state, gastric emptying is decreased in the first but not the second and third trimesters. Before elective Caesarean delivery, carbohydrate drink or tea with milk leads to no difference in gastric cross-sectional area at 2 h relative to fasting or water. Following a standard fast for elective Caesarean delivery, patients may still have high-risk gastric contents. Compared with the nonpregnant state and third trimester, gastric emptying is delayed in labour, although the choice of analgesia has modifying effects. Systemic opioids delay gastric emptying. Epidural analgesia increases gastric emptying, but not back to baseline. Intrathecal analgesia delays gastric emptying relative to epidural analgesia. Women in labour who have eaten solids in the last 8 h still have high-risk gastric contents present in the stomach. The evidence with respect to the postpartum period is conflicting. In conclusion, inconsistencies in the literature reflect the unpredictability of gastric emptying in pregnancy and underline the potential value of gastric ultrasound in women who are pregnant.

Impact of maternal posture on fetal physiology in human pregnancy: a narrative review

In numerous medical conditions, including pregnancy, gravity and posture interact to impact physiology and pathophysiology. Recent investigations, for example, pertaining to maternal sleeping posture during the third trimester and possible impact on fetal growth and stillbirth risk highlight the importance and potential clinical implications of the subject. In this review, we provide an extensive discussion of the impact of maternal posture on fetal physiology from conception to the postpartum period in human pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 242 studies from 1991 through 2021, inclusive, that met our inclusion criteria. Herein, we provide a synthesis of the resulting literature. In the first section of the review, we group the results by the impact of maternal posture at rest on the cervix, uterus, placenta, umbilical cord, amniotic fluid, and fetus. In the second section of the review, we address the impact on fetal-related outcomes of maternal posture during various maternal activities (e.g., sleep, work, exercise), medical procedures (e.g., fertility, imaging, surgery), and labor and birth. We present the published literature, highlight gaps and discrepancies, and suggest future research opportunities and clinical practice changes. In sum, we anticipate that this review will shed light on the impact of maternal posture on fetal physiology in a manner that lends utility to researchers and clinicians who are working to improve maternal, fetal, and child health.

Maternal positional therapy for fetal growth and customised birth weight centile benefit in a Bayesian reanalysis of a double-blind, sham-controlled, randomised clinical trial

OBJECTIVES

To update the Ghana PrenaBelt Trial's (GPT) primary outcome data with the latest fetal growth standard and reanalyse it. To estimate the posterior probability, under various clinically relevant prior probabilities, of maternal nightly positional therapy (PT) throughout the third-trimester having a beneficial effect on customised birth weight centile (CBWC) using Bayesian analyses.

DESIGN

A reanalysis of a double-blind, sham-controlled, randomised clinical trial.

SETTING

A single, tertiary-level centre in Accra, Ghana.

PARTICIPANTS

Two-hundred participants entered, 181 completed and 167 were included in the final analysis. Participants were Ghanaian, healthy, aged 18-35 years, with low-risk, singleton pregnancies in their third-trimester, with Body Mass Index<35 kg/m2 at the first antenatal appointment for the index pregnancy and without known fetal abnormalities, pregnancy complications or medical conditions complicating sleep.

INTERVENTIONS

Participants were randomised to receive treatment with either a PT or sham-PT device.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the CBWC using the latest Perinatal Institute, Gestation-Related Optimal Weight calculator. Using Bayesian methods, posterior probabilities of achieving a greater than 0%, 5% and 10% benefit in CBWC with PT were estimated. There was no secondary outcome.

RESULTS

The median (IQR) CBWC was 42% (15-71) and 28% (9-52) in the PT and sham-PT groups, respectively (difference 8.4%; 95% CI -0.30 to 18.2; p=0.06). For achieving a >0%, >5% and >10% gain in CBWC with PT, the posterior probabilities were highly probable, probable and unlikely, respectively, given a range of prior probabilities reflecting varying degrees of pre-existing enthusiasm and scepticism.

CONCLUSIONS

Maternal nightly PT throughout the third-trimester did not have a statistically significant effect on CBWC on a frequentist analysis using the latest fetal growth standard. However, from a Bayesian analysis, clinicians can infer that PT is likely to benefit fetal growth but with a modest effect size.

TRIAL REGISTRATION NUMBER

NCT02379728.

Effects of Right Lateral Position on Changes of Fetal Hemodynamics in Late Pregnancy

OBJECTIVE

We aim to evaluate the effect of right lateral position on fetal hemodynamics (including umbilical artery [UA] and middle cerebral artery (MCA) blood flow-velocity waveform).

METHODS

In total, 150 low-risk singleton full-term pregnant women were included in the study from November 2021 to January 2022. Doppler flow velocity waveforms of the fetal UA and MCA tested by ultrasound were collected in gestation of 37-40 weeks. Computational analysis was performed using the one-way ANOVA test.

RESULTS

Compared with the maternal left lateral position, there was a significant increase in Doppler indices of UA-RI (P = .033), UA-S/D (P = .019) and MCA-PSV (P = .021) and a significant decrease in MCA-RI (P = .030) in the supine position group. There was no statistical significance in all Doppler indices between the left and right lateral position (P > .05). Among the Doppler indices of three different maternal positions, there was no significance in both UA-PI and MCA-PI (P > .05).

CONCLUSION

There were no significant differences on changes of the fetal hemodynamics between left and right lateral positions. Pregnant women could adopt to lie in the left or right lateral position alternately to relieve the discomfort in late pregnancy.

Vision-based detection and quantification of maternal sleeping position in the third trimester of pregnancy in the home setting-Building the dataset and model

In 2021, the National Guideline Alliance for the Royal College of Obstetricians and Gynaecologists reviewed the body of evidence, including two meta-analyses, implicating supine sleeping position as a risk factor for growth restriction and stillbirth. While they concluded that pregnant people should be advised to avoid going to sleep on their back after 28 weeks' gestation, their main critique of the evidence was that, to date, all studies were retrospective and sleeping position was not objectively measured. As such, the Alliance noted that it would not be possible to prospectively study the associations between sleeping position and adverse pregnancy outcomes. Our aim was to demonstrate the feasibility of building a vision-based model for automated and accurate detection and quantification of sleeping position throughout the third trimester-a model with the eventual goal to be developed further and used by researchers as a tool to enable them to either confirm or disprove the aforementioned associations. We completed a Canada-wide, cross-sectional study in 24 participants in the third trimester. Infrared videos of eleven simulated sleeping positions unique to pregnancy and a sitting position both with and without bed sheets covering the body were prospectively collected. We extracted 152,618 images from 48 videos, semi-randomly down-sampled and annotated 5,970 of them, and fed them into a deep learning algorithm, which trained and validated six models via six-fold cross-validation. The performance of the models was evaluated using an unseen testing set. The models detected the twelve positions, with and without bed sheets covering the body, achieving an average precision of 0.72 and 0.83, respectively, and an average recall ("sensitivity") of 0.67 and 0.76, respectively. For the supine class with and without bed sheets covering the body, the models achieved an average precision of 0.61 and 0.75, respectively, and an average recall of 0.74 and 0.81, respectively.

Contrast-Enhanced Ultrasound for Assessing Abdominal Conditions in Pregnancy

Background and objectives: Native ultrasound is the most common imaging modality in obstetrics. The use of contrast-enhanced ultrasound (CEUS) during pregnancy has not been officially approved by leading societies for obstetrics and ultrasound. The present study aims to monitor the safety and diagnostic performance of CEUS for assessing abdominal issues in five pregnant women. Materials and Methods: Five pregnant patients who underwent a total of 11 CEUS examinations between June 2020 and October 2020 were included (mean age: 34 years; mean time of pregnancy: 21 weeks). All CEUS scans were interpreted by one experienced consultant radiologist (EFSUMB Level 3). Results: Upon contrast application, no maternal nor fetal adverse effects were observed. Moreover, no fetal contrast enhancement was observed in any patient. CEUS helped to diagnose renal angiomyolipoma, pyelonephritis, necrotic uterine fibroid, gallbladder polyp, and superior mesenteric vein thrombosis. Conclusions: In our study, off-label use of CEUS showed an excellent safety profile allowing the avoidance of ionizing radiation exposure as well as contrast agents in case of CT or use of gadolinium-based contrast agents in case of MRI. CEUS is a promising diagnostic instrument for facilitating clinical decision-making and improving the management of pregnant women.

Sleep in the Supine Position during Pregnancy Is Associated with Fetal Cerebral Redistribution

The supine sleep position in late pregnancy is a major risk factor for stillbirth, with a population attributable risk of 5.8% and one in four pregnant women reportedly sleeping in a supine position. Although the mechanisms linking the supine sleep position and late stillbirth remain unclear, there is evidence that it exacerbates pre-existing maternal sleep disordered breathing, which is another known risk factor for adverse perinatal outcomes. Given that maternal sleep position is a potentially modifiable risk factor, the aim of this study was to characterize and correlate uteroplacental and fetal hemodynamics, including cardiac function, in a cohort of women with apparently uncomplicated pregnancies with their nocturnal sleep position. This was a prospective observational cohort study at an Australian tertiary obstetric hospital. Women were asked to complete a series of questions related to their sleep position in late pregnancy after 35 weeks of completed gestation. They also underwent an ultrasound assessment where Doppler indices of various fetoplacental vessels and fetal cardiac function were measured. Regional cerebral perfusion was also assessed. Pregnancy outcome data was extracted from the electronic hospital database for analysis. A total of 274 women were included in the final analysis. Of these, 78.1% (214/274) reported no supine sleep, and 21.9% (60/274) reported going to sleep in a supine position. The middle cerebral artery, anterior cerebral artery, and vertebral artery pulsatility indices were all significantly lower in the supine sleep cohort, as was the cerebroplacental ratio. There were no significant differences in the mode or indication for delivery or in serious neonatal outcomes, including 5-min Apgar score < 7, acidosis, and neonatal intensive care unit admission between cohorts. Women in the supine cohort were more likely to have an infant with a BW > 90th centile (p = 0.04). This data demonstrates fetal brain sparing in association with the maternal supine sleep position in a low-risk population. This data contributes to the growing body of literature attempting to elucidate the etiological pathways responsible for the association of late stillbirth with the maternal supine sleep position.

Unilateral nonhaemorrhagic adrenal infarction as a cause of abdominal pain during pregnancy

Adrenal infarction is usually associated with bilateral adrenal hemorrhage in the setting of antiphospholipid syndrome or hemodynamic variation. Few cases of unilateral nonhemorrhagic adrenal infarction (NHAI) have been described in the literature. Here, we report a case occurring during pregnancy. A 30-year-old woman presented at 32 weeks of gestation with sudden-onset right abdominal pain and contractions. Unilateral adrenal infarction was diagnosed following computed tomography (CT). It showed an enlarged right adrenal, without hyperenhancement. Because of persisting contractions, despite medical care, she delivered a healthy, albeit premature, girl. Abdominal pain decreased right after delivery. Three month later, CT imaging showed atrophy of the right adrenal and a normal left adrenal. The patient's adrenal hormonal function was normal. Accurate diagnosis of NHAI remains difficult as its clinical presentation is not specific. It can only be performed with adrenal imaging. Magnetic resonance imaging shows diffuse enlargement of one or both adrenals and an edema on T2-weighted images. Anticoagulation therapy may be discussed. Patients should be evaluated between 3 and 6 months after the event to assess adrenal size and function. In summary, NHAI during pregnancy is probably underdiagnosed and obstetricians should be aware of this or diagnostic difficulty.

Prospective Evaluation of Maternal Sleep Position Through 30 Weeks of Gestation and Adverse Pregnancy Outcomes

OBJECTIVE

To examine the relationship between prospectively assessed maternal sleep position and subsequent adverse pregnancy outcomes.

METHODS

This was a secondary analysis of a prospective observational multicenter cohort study of nulliparous women with singleton gestations who were enrolled between October 2010 and May 2014. Participants had three study visits that were not part of clinical care. They prospectively completed in-depth sleep questionnaires between 6 0/7 and 13 6/7 weeks of gestation and 22 0/7 and 29 6/7 weeks of gestation, the first and third study visits. A subset of women also underwent level 3 home sleep tests using the Embletta Gold device. The primary outcome was a composite of adverse pregnancy outcomes such as stillbirth, a small-for-gestational-age newborn, and gestational hypertensive disorders.

RESULTS

A total of 8,706 (of 10,038) women had data from at least one sleep questionnaire and for pregnancy outcomes, and they comprised the population for this analysis. The primary outcome occurred in 1,903 pregnancies (22%). There was no association between reported non-left lateral or supine sleep during the last week of the first visit (adjusted odds ratio [aOR] 1.00 [95% CI 0.89-1.14]) or third visit (aOR 0.99 [95% CI 0.89-1.11] and the composite or any individual outcome, except for an apparent protective effect for stillbirth at the third visit (aOR 0.27 (95% CI 0.09-0.75). Women with objectively measured supine sleep position for at least 50% of the time were no more likely than those in the supine position 50% or less of the time to have the composite adverse outcome.

CONCLUSIONS

Going to sleep in the supine or right lateral position, as self-reported before the development of pregnancy outcome and objectively assessed through 30 weeks of gestation, was not associated with an increased risk of stillbirth, a small-for-gestational-age newborn, or gestational hypertensive disorders.

Effect of Right-Lateral Versus Left-Lateral Tilt Position on Compression of the Inferior Vena Cava in Pregnant Women Determined by Magnetic Resonance Imaging

BACKGROUND

Despite the existing dogma that women undergoing cesarean delivery under spinal anesthesia should be positioned with a 15° left-lateral tilt, the patients were actually positioned in a right-lateral tilt position in several of the original studies. The superiority of right versus left positioning for optimal inferior vena cava volume is unknown. We used magnetic resonance imaging to compare the effects of right-lateral and left-lateral tilt positions on abdominal aortic and inferior vena cava volumes in pregnant women.

METHODS

Thirteen women with singleton pregnancies and gestational age 31-39 weeks underwent magnetic resonance imaging while in the supine position, and in the left-lateral (15° and 30°) and right-lateral tilt (15° and 30°) positions, which were maintained by placing a 1.5-m-long piece of polyethylene foam under either side of the body. Abdominal aorta and inferior vena cava volume were measured between the L1-L2 disk and L3-L4 disk levels using magnetic resonance images.

RESULTS

Aortic volume did not differ significantly among any of the positions examined. Mean inferior vena cava volume was significantly greater in the 30° left-lateral tilt position than in the 15° right-lateral tilt (10.7 ± 7.5 vs 5.9 ± 5.1 mL; mean difference, 4.8; 95% CI, 1.2-8.5; P = .002) and 30° right-lateral tilt (10.7 ± 7.5 vs 5.9 ± 2.5 mL; mean difference, 4.8; 95% CI, 1.2-8.4; P = .002) positions. Mean inferior vena cava volume in the 15° left-lateral tilt position did not differ significantly from that in the 15° right-lateral tilt (mean difference, 0.4; 95% CI, -3.2 to 4.0; P = 1.000) or 30° right-lateral tilt (mean difference, 0.4; 95% CI, -3.3 to 4.0; P = 1.000) positions. Mean inferior vena cava volume in the supine position only differed significantly from that in the 30° left-lateral tilt position (5.2 ± 3.8 vs 10.7 ± 7.5 mL; mean difference, 5.5; 95% CI, 1.8-9.1; P < .001). The greatest inferior vena cava volume was observed in the 30° left-lateral tilt position in 9 of 13 subjects (70%), and in the 30° right-lateral tilt in 3 subjects (23%).

CONCLUSIONS

The 30° left-lateral tilt position most consistently reduced inferior vena cava compression by the gravid uterus compared with the supine position. Mean inferior vena cava volume in pregnant women was not increased at either angle of the right-lateral tilt position compared with the 30° left-lateral tilt position. However, in a subset of patients, the 30° right-lateral tilt position achieved the optimal inferior vena cava volume. Further investigation to understand this variability is warranted.

An Individual Participant Data Meta-analysis of Maternal Going-to-Sleep Position, Interactions with Fetal Vulnerability, and the Risk of Late Stillbirth

BACKGROUND

Maternal supine going-to-sleep position has been associated with increased risk of late stillbirth (≥ 28 weeks), but it is unknown if the risk differs between right and left side, and if some pregnancies are more vulnerable.

METHODS

Systematic searches were undertaken for an individual-level participant data (IPD) meta-analysis of case-control studies, prospective cohort studies and randomised trials undertaken up until 26 Jan, 2018, that reported data on maternal going-to-sleep position and stillbirth. Participant inclusion criteria included gestation ≥ 28 weeks', non-anomalous, singleton pregnancies. The primary outcome was stillbirth. A one-stage approach stratified by study and site was used for the meta-analysis. The interaction between supine going-to-sleep position and fetal vulnerability was assessed by bi-variable regression. The multivariable model was adjusted for a priori confounders. Registration number: PROSPERO, CRD42017047703.

FINDINGS

Six case-control studies were identified, with data obtained from five (cases, n = 851; controls, n = 2257). No data was provided by a sixth study (cases, n = 100; controls, n = 200). Supine going-to-sleep position was associated with increased odds of late stillbirth (adjusted odds ratio [aOR] 2.63, 95% CI 1.72-4.04, p < 0.0001) compared with left side. Right side had similar odds to left (aOR 1.04, 95% CI 0.83-1.31, p = 0.75). There were no significant interactions between supine going-to-sleep position and assessed indicators of fetal vulnerability, including small-for-gestational-age infants (p = 0.32), maternal obesity (p = 0.08), and smoking (p = 0.86). The population attributable risk for supine going-to-sleep position was 5.8% (3.2-9.2).

INTERPRETATION

This IPD meta-analysis confirms that supine going-to-sleep position is independently associated with late stillbirth. Going-to-sleep on left or right side appears equally safe. No significant interactions with our assessed indicators of fetal vulnerability were identified, therefore, supine going-to-sleep position can be considered a contributing factor for late stillbirth in all pregnancies. This finding could reduce late stillbirth by 5.8% if every pregnant woman ≥ 28 weeks' gestation settled to sleep on her side.

Trapped vessel of abdominal pain with hepatomegaly: A case report

Abdominal pain with elevated transaminases from inferior vena cava (IVC) obstruction is a relatively common reason for referral and further workup by a hepatologist. The differential for the cause of IVC obstruction is extensive, and the most common etiologies include clotting disorders or recent trauma. In some situations the common etiologies have been ruled out, and the underlying process for the patient’s symptoms is still not explained. We present one unique case of abdominal pain and hepatomegaly secondary to IVC constriction from extrinsic compression of the diaphragm. Based on this patient’s presentation, we urge that physicians be cognizant of the IVC diameter and consider extrinsic compression as a contributor to the patient’s symptoms. If IVC compression from the diaphragm is confirmed, early referral to vascular surgery is strongly advised for further surgical intervention.

Agreement between preload reserve measured by impedance cardiography and echocardiography during pregnancy

Purpose

Accurate assessment of cardiac function is important during pregnancy. Echocardiography and impedance cardiography (ICG) are commonly used noninvasive methods to measure stroke volume (SV) and cardiac output (CO). The difference in stroke volume (ΔSV) or cardiac output (ΔCO) measured at baseline and after passive leg raising (PLR) is a measure of preload reserve that predicts volume responsiveness. However, the agreement between these two methods in measuring preload reserve during pregnancy is unclear. The aim of our study was to investigate the correlation and the agreement between Doppler echocardiography and ICG in assessing preload reserve in pregnant women.

Methods

In this prospective observational cross-sectional study, preload reserve was assessed by measuring the SV and CO during baseline and 90 s after PLR simultaneously by Doppler echocardiography and ICG in healthy pregnant women during the second and third trimesters. Bland–Altman analysis was used to determine the agreement between the two methods. Bias was calculated as the mean difference between two methods and precision as 1.96 SD of the difference.

Results

A total of 53 pregnant women were included. We found a statistically significant correlation between ΔSV (R = 0.56, p < 0.0001) and ΔCO (R = 0.39, p = 0.004) measured by ICG and Doppler echocardiography. The mean bias for ΔSV was 2.52 ml, with a precision of 18.19 ml. The mean bias for ΔCO was 0.21 l/min, with a precision of 1.51 l/min.

Conclusion

There was a good agreement and a statistically significant correlation between ICG and Doppler echocardiography for measuring preload reserve.

Differential Diagnosis of an Inferior Vena Cava Thrombosis/Hepatic Cyst Using an Abdominal Sonogram, Echocardiogram, Venography, and Computed Tomography Angiogram

The role of cardiac sonographers, as health care professionals, comprises facilitating a cardiologist’s diagnosis of valvular lesions, coronary artery disease, and congenital defects and assessing right-side pulmonary complications and so on. Occasionally, communication of differential diagnoses across several modalities, specialties, and healthcare providers is compulsory, in order to accurately confirm or deny an appropriate diagnosis for patients with unique presentations. This case study highlights the vital role of abdominal sonography, echocardiography, venography, and computed tomography in the diagnosis of a hepatic cyst. In addition, it demonstrates the appropriate measures that cardiac sonographers can take to fully investigate these lesions, especially when they are presumed to be a thrombosed inferior vena cava.

Transient fetal blood redistribution associated with maternal supine position

OBJECTIVE

To investigate whether fetal blood circulation is influenced by the maternal supine position.

METHODS

The inclusion criteria were good health, a singleton pregnancy, maternal age between 18 and 40 years, gestational age between 36 and 40 weeks, and an agreement to participate in the study. Each participant (n=20) was initially asked to adopt the left lateral position for 5 min, while fetal Doppler measurements were taken of the fetal middle cerebral artery (MCA), umbilical artery (UA), and umbilical vein (UV). Subsequently, they were asked to change to the supine position for Doppler measurements at 5 and at 10 min.

RESULTS

When a woman remained in the supine position for 5 min, there was a significant reduction in fetal MCA-pulsatility index (PI) (median 1.70 vs. 1.42, P=0.003). This reduction did not persist after 10 min (median 1.70 vs. 1.65 P=1.0). There was no significant difference between the left lateral and the supine position at 5 and at 10 min in terms of UA-PI (0.853 vs. 0.870 vs. 0.858, P=0.850), UV flow (217 vs. 242 vs. 236 mL/min, P=0.263), and normalized UV flow (72.2 vs. 80.8 vs. 78.8 mL/min/kg, P=0.271).

CONCLUSIONS

Changing maternal position from the left lateral to the supine position caused a reduction in resistance in fetal MCA and no changes in UA or UV indices. However, despite the changes in cerebral circulation which occurred at 5 min by shifting position, they did not remain for 10 min. The changes may be related to reduction in maternal oxygen saturation as there was no decrease in UV blood flow.

Vena cava compression syndrome in patients with obesity presenting with edema and thrombosis

OBJECTIVE

Obesity is a risk factor for cardiovascular disease and venous thrombosis. Previous studies have shown that in late pregnancy a compression of the inferior vena cava (VCI) leads to a hypotensive syndrome. The objective of this study was to explore the correlation between obesity and an elevated pressure in the VCI simulating obesity-induced vena cava compression syndrome.

METHODS

A left and right heart catheterization was performed in 29 patients. After right atrial pressure measurement, the catheter was pulled back through the VCI, and the pressure gradient between the thoracic and abdominal vena cava was measured. We determined the correlation between the BMI and the pressure gradient.

RESULTS

In 29 patients, a high BMI was associated with an increased pressure gradient between the thoracic and abdominal vena cava (r = 0.66). This correlation was particularly close in patients with a BMI >30 kg/m(2) (P = 0.0008). Two patients had complications such as recurrent thrombosis, with one of them having the highest pressure gradient of 16 mm Hg.

CONCLUSIONS

Because mechanical obstruction of the VCI leads to an increased risk for venous thrombosis in patients with obesity, this finding needs to be considered in the decision-making for interventional treatments like bariatric surgery.

Endoplasmic reticulum stress in the pathogenesis of early-onset pre-eclampsia

Recent data have provided molecular evidence of high levels of endoplasmic reticulum stress in non-laboured placentas from cases of early-onset pre-eclampsia. Endoplasmic reticulum stress is intricately linked to oxidative stress, and the two often share the same aetiology. In the case of pre-eclampsia this is likely to be placental malperfusion, secondary to deficient conversion of the spiral arteries. Endoplasmic reticulum stress activates a number of signalling pathways aimed at restoring homeostasis, but if these attempts fail then the apoptotic machinery may be activated. The potential consequences for placental development and function are numerous and diverse. Inhibition of protein synthesis results in lower levels of many kinases, growth factors and regulatory proteins involved in cell cycle control, and experiments in vitro reveal that endoplasmic reticulum stress slows cell proliferation. Chronic, low levels of stress during the second and third trimesters may therefore result in a growth restricted phenotype. Higher levels of endoplasmic reticulum stress lead to activation of pro-inflammatory pathways, a feature of pre-eclampsia that may contribute to maternal endothelial cell activation. These findings emphasise the complexity of cellular responses to stress, and the need to approach these in a holistic fashion when considering therapeutic interventions.

Typical sleep positions in pregnant women

OBJECTIVE

Maternal supine posture in late pregnancy and labor is known to compromise maternal hemodynamics and subsequently affect the fetus. Recently, maternal supine sleep position during late pregnancy has been postulated to play a role in stillbirth. However, no objective data exist regarding how often pregnant women sleep supine. This study was therefore conducted to determine the proportion of pregnant women who spend time asleep in the supine position.

METHODS

A secondary analysis of data from pregnant women who underwent home sleep studies.

RESULTS

Of 51 pregnant women, mean gestational age 28.3±6.9weeks, the vast majority of women (82.4%) spent some time sleeping in the supine position. The median proportion of overall time spent in the supine sleep position was 26.5% (90%CI 0.0-82.9%).

CONCLUSION

Our data suggest that if supine position plays a role in stillbirth, most women may benefit from education regarding sleep position.

PRACTICE IMPLICATIONS

Most pregnant women spend time asleep on their back. Given the known data on supine posture and maternal cardiovascular compromise together with emerging data on supine sleep position and stillbirth, it may be pertinent for healthcare providers to provide pregnant women with information about sleep position particularly during late pregnancy.

Resuscitation of the pregnant patient: What is the effect of patient positioning on inferior vena cava diameter?

STUDY OBJECTIVE

Patients in the third trimester of pregnancy presenting to the emergency department (ED) with hypotension are routinely placed in the left lateral tilt (LLT) position to relieve inferior vena cava (IVC) compression from the gravid uterus thereby increasing venous return. However, the relationship between patient position and proximal intrahepatic IVC filling has never assessed directly. This study set out to determine the effect of LLT position on intrahepatic IVC diameter in third trimester patients under real-time visualization with ultrasound.

METHODS

This prospective observational study on the labor and delivery floor of a large urban academic teaching hospital enrolled patients between 30 and 42 weeks estimated gestational age from August 2011 to March 2012. Patients were placed in three different positions: supine, LLT, and right lateral tilt (RLT). After the patient was in each position for at least 3 min, IVC ultrasound using the intercostal window was performed by one of three study sonologists. Maternal and fetal hemodynamics were also monitored and recorded in each position.

RESULTS

A total of 26 patients were enrolled with one excluded from data analysis due to inability to obtain IVC measurements. The median IVC maximum diameter was 1.26 cm (95% confidence interval [CI] 1.13-1.55) in LLT compared to 1.13 cm (95% CI 0.89-1.41) in supine, p=0.01. When comparing each individual patient's LLT to supine measurement, LLT lead to an increase in maximum IVC diameter in 76% (19/25) of patients with the average LLT measurement 29% (95% confidence interval 10-48%) larger. Six patients had the largest maximum IVC measurement in the supine position. No patients experienced any hemodynamic instability or distress during the study.

CONCLUSION

IVC ultrasound is feasible in late pregnancy and demonstrates an increase in diameter with LLT positioning. However, a quarter of patients had a decrease in IVC diameter with tilting and, instead, had the largest IVC diameter in the supine position suggesting that uterine compression of the IVC may not occur universally. IVC assessment at the bedside may be a useful adjunct in determining optimal positioning for resuscitation of third trimester patients.

Management of angiomyolipoma vena cava thrombus during pregnancy

BACKGROUND

Angiomyolipoma can worsen during pregnancy. Inferior vena cava thrombus of renal angiomyolipoma during pregnancy is rare, and threatens to cause massive emboli. We report a case of vena cava tumor thrombectomy during the second trimester of pregnancy with delayed renal tumorectomy.

CASE

A 34-year-old woman with bilateral known angiomyolipomas presented asymptomatic at 30 weeks of gestation with an inferior vena cava thrombus at renal follow-up ultrasonography. Retro-hepatic thrombus had fatty signal on magnetic resonance imaging (MRI). The woman had renal vein and vena cava tumor initial thrombectomy, and had normal cesarean delivery at 39 weeks of gestation. The tumor was treated by postpartum right partial nephrectomy.

CONCLUSION

Successful angiomyolipoma isolated thrombectomy during pregnancy with delayed partial nephrectomy is possible. Angiomyolipoma needs follow-up during pregnancy with repeated renal ultrasonography.

Prediction of hypotension during spinal anesthesia for cesarean section and its relation to the effect of crystalloid or colloid preload

BACKGROUND

If parturients prone to develop caval compression in the supine position were identified before delivery, this might be a method of predicting hypotension during caesarean section under spinal anesthesia. Colloid preloading is superior to crystalloid in reducing the risk for spinal anesthetic-induced hypotension. It is postulated that parturients preoperatively susceptible to the supine position would benefit the most from colloid preloading.

METHODS

Fifty-five healthy parturients scheduled for elective cesarean section under spinal anesthesia were preoperatively investigated with a supine stress test with measurement of maternal heart rate, blood pressure, right uterine artery pulsatility index and symptoms in the left lateral and supine positions. They were then randomized to receive a colloid or crystalloid preload before anesthesia.

RESULTS

The stress test was positive, indicating a reduced tolerance to the supine position, in 36%. The sensitivity and specificity of the stress test for clinically significant hypotension (symptomatic hypotension) for patients randomized to the crystalloid group (n=25) were 69 and 92% respectively. Patients with a positive stress test receiving a crystalloid preload showed a higher frequency of hypotension compared to all other groups, 90% vs. 33%, (P=0.003) and also a greater need for ephedrine, mean dose (SD): 20.0 (9.7) vs. 8.4 (9.0) mg (P=0.002).

CONCLUSIONS

Pregnant women with a positive preoperative supine stress test constitute a subset at increased risk for clinically significant hypotension during cesarean delivery under spinal anesthesia. These women seem more likely to benefit from prophylactic colloid solution than women with a negative stress test.

Changes in the size of maternal inferior vena cava during pregnancy

AIMS

To investigate the changes in the size of maternal inferior vena cava (IVC) during normal pregnancy.

METHODS

The diameter and the area of IVC were measured in 32 non-pregnant and 214 pregnant women by ultrasonography. They were measured not only in the supine but also in the complete left lateral position when gestation was over 16 weeks.

RESULTS

IVC in the 4-7 weeks pregnant group was larger than that in the non-pregnant group, and it decreased as gestation progressed during an early stage of pregnancy. After 16 weeks gestation, it demonstrated no change, at least for depending on the periods when the mother was in the supine position. On the contrary, they increased with the gestational progress as for the maternal left lateral position.

CONCLUSIONS

The size of IVC at an early stage of pregnancy is enlarged, suggesting an underfilling state of arterial circulation. In the second and third trimesters, it is stationary when the mother is supine. In the left lateral position, it increases as the gestation progresses, reflecting blood volume expansion during pregnancy.

Inferior vena cava diameter and the risk of pregnancy-induced hypertension and fetal compromise

OBJECTIVE

Our objective was to investigate a possible clinical usefulness of the measurement of the inferior vena caval diameter (IVCD) during the late second trimester in predicting obstetrical complications.

METHODS

IVCD was measured in the supine and complete left lateral positions in 281 pregnant women at 24-27 weeks' gestation.

RESULTS

In 35 cases who showed the IVCD < or = 10 percentile in the complete left lateral position, there were six cases with pregnancy-induced hypertension and seven cases with a compromized fetus (with fetal distress and/or an Apgar score < 7 at 1 min), each incidence being significantly higher compared with cases with IVCD > 10 percentile.

CONCLUSION

The measurement of IVCD in the complete left lateral position may provide a valuable tool in predicting pregnancy outcome given its non-invasiveness and easiness.