Volume Manipulation Research Articles

An innovative patternable microelectrode bonding technology for high-performance and cost-effective sealing in microfluidic chips

Microfluidic chips pose as an interdisciplinary frontier as they integrate various fields, while typically serving as a novel technological platform for precise manipulation of minute liquid volumes and biological analysis. However, the chase for enhanced bonding quality in order to fabricate these chips correctly, has led to the use of increasingly complex technology, limiting the marketability of microfluidic products. In this work, a novel microelectrode bonding technology is proposed, which addresses the demands for reliable, low-cost, and high-throughput bonding. The proposed process utilizes the Joule heating effect of microelectrodes at low voltages, in order to rapidly generate sufficient heat and allow for the successful bonding of the chip. The material used for the microelectrodes is nickel, and the method chosen for their fabrication is small-batch electrodeposition. The microelectrodes and microchannels morphology are characterized by Extended Depth of Field Microscopy, while the quality of heating produced is assessed by a high-speed infrared camera. The finalized bonding strength is characterized by measuring the microchannel burst pressure, using an apparatus comprising of a syringe pump, a precision pressure gauge, and a connecting tubing. The results prove that this is a rapid polymer bonding method, which uses less than 3 Volts. Additionally, the results underscore the process’s effectiveness, yielding chips with burst strengths over 2.9 MPa, while microchannel deformations are kept under 10 %. Finally, the advantages of the technology are discussed and its limitations are eliminated by further conceptualization. The proposed method uses no chemicals or contaminants, nor complex equipment, rendering it simple, green, and sustainable. This paves the way for the development of new efficient and greener paradigms, aiming towards leading engineering and manufacturing to a sustainable future.

Amino acid assisted-construction of 2D-hierarchical MFI zeolites for adsorption of rhodamine B

Hierarchical and two-dimensional (2D) zeolites have drawn much attention in catalysis and separation process due to their fast mass transfer. However, the facile manipulation in controllable mesopore volumes and morphologies for hierarchical nanozeolites is full of challenges. Herein, a facile strategy is presented for the synthesis of single-crystalline 2D hierarchical MFI zeolite nanosheets (HNSs) with tunable mesopore volumes through the amino acid-assisted crystallization of nucleated amorphous silicon precursors (NASPs). The tailored synthesis of HNSs with controllable aspect ratios ((Lc + La)/Lb), b-axis thicknesses (a few tens of nanometers) and mesopore volumes is achieved by adjusting the preparation of the NASPs and the amount of amino acid in the synthesis mixture. The HNSs exhibit large BET surface area (>400 m2 g-1), high micropore volume (0.16–0.18 cm3 g−1) as well as rich mesopore volume (>0.10 cm3 g−1), indicating the high crystallinity of the hierarchical zeolite nanosheets. Specially, the higher adsorption capability and faster adsorption rate for the dye (Rhodamine B) adsorption demonstrate the excellent performance of the hierarchical zeolite nanosheets, which exhibits the maximum adsorption capacity of 115.7 mg g−1. The controllable manipulation of mesoporous volumes and morphologies in MFI zeolites represents a significant contribution to the field of zeolite microstructure engineering.

How do rest-pause and sarcoplasma stimulating training models affect metabolic and psychoaffective responses in bodybuilding athletes compared to traditional training?

Strength training (ST) is a strategy to enhance quality of life through increased strength, muscle hypertrophy, and functional capacity. Training systems are associated with manipulation of volume and intensity, generating different stimuli, such as Rest-Pause (RP) and Sarcoplasmic Stimulating Training (SST). These systems induce greater mechanical and physiological stress, leading to increased strength and muscle hypertrophy. However, the metabolic and psycho-affective effects of advanced systems in experienced practitioners remain inconclusive. The purpose of the study is to analyze the acute effects of RP, SST, and Traditional (TMS) systems on metabolic and psycho-affective responses in adult men. This experimental crossover study assessed 15 subjects (30.38 ± 2.06 years; 88.40 ± 6.50 kg; 1.74 ± 0.07 cm) experienced in ST, evaluated under TMS, RP, and SST during flat bench press and leg press 45° exercises. Body composition, muscular strength via 1-RM testing, lactate concentration (LAC), and psycho-affective measures (Rating of Perceived Exertion-RPE; Visual Analog Scale-VAS; Feeling Scale-FS) were determined. Statistical analysis was performed using the Minitab software, with p ≤ 0.05, IC-95%). The finals results showed SST exhibited a 38.10% lower LAC concentration post-training session compared to TMS, while RP showed 37.20% lower LAC concentration than TMS post-session. Average RPE values for RP and SST were higher (8.50 ± 1.10 and 8.60 ± 0.90, respectively) than TMS (6.00 ± 1.10). VAS displayed higher average values for RP and SST (8.00 ± 2.00 and 8.00 ± 1.00, respectively) compared to TMS (5.00 ± 1.00), with affective ratings indicating positive values for TMS and values between 0 and -5 for RP (40%) and SST (60%) post-training sessions, suggesting that RP and SST induced less affective response than TMS. The results lead to the conclusion that manipulation of training volume and intensity led to higher RPE and pain (VAS). The data suggest that inappropriate prescription of these systems could lead to greater displeasure, leading us to hypothesize that a higher likelihood of discontinuation from strength training programs would occur, suggesting that greater repetition volumes (RP and SST) should be targeted at individuals with a higher training level.

Digital Microfluidics for Sample Preparation in Low-Input Proteomics.

Low-input proteomics, also referred to as micro- or nanoproteomics, has become increasingly popular as it allows one to elucidate molecular processes in rare biological materials. A major prerequisite for the analytics of minute protein amounts, e.g., derived from low cell numbers, down to single cells, is the availability of efficient sample preparation methods. Digital microfluidics (DMF), a technology allowing the handling and manipulation of low liquid volumes, has recently been shown to be a powerful and versatile tool to address the challenges in low-input proteomics. Here, an overview is provided on recent advances in proteomics sample preparation using DMF. In particular, the capability of DMF to isolate proteomes from cells and small model organisms, and to perform all necessary chemical sample preparation steps, such as protein denaturation and proteolytic digestion on-chip, are highlighted. Additionally, major prerequisites to making these steps compatible with follow-up analytical methods such as liquid chromatography-mass spectrometry will be discussed.

Multicolor-Assay-on-a-Chip Processed by Robotic Operation (MACpro) with Improved Diagnostic Accuracy for Field-Deployable Detection.

The ability to deploy decentralized laboratories with autonomous and reliable disease diagnosis holds the potential to deliver accessible healthcare services for public safety. While microfluidic technologies provide precise manipulation of small fluid volumes with improved assay performance, their limited automation and versatility confine them to laboratories. Herein, we report the utility of multicolor assay-on-a-chip processed by robotic operation (MACpro), to address this unmet need. The MACpro platform comprises a robot-microfluidic interface and an eye-in-hand module that provides flexible yet stable actions to execute tasks in a programmable manner, such as the precise manipulation of the microfluidic chip along with different paths. Notably, MACpro shows improved detection performance by integrating the microbead-based antibody immobilization with enhanced target recognition and multicolor sensing via Cu2+-catalyzed plasmonic etching of gold nanorods for rapid and sensitive analyte quantification. Using interferon-gamma as an example, we demonstrate that MACpro completes a sample-to-answer immunoassay within 30 min and achieves a 10-fold broader dynamic range and a 10-fold lower detection limit compared to standard enzyme-linked immunosorbent assays (0.66 vs 5.2 pg/mL). MACpro extends the applications beyond traditional laboratories and presents an automated solution to expand diagnostic capacity in diverse settings.

Shape-memory microfluidic chips for fluid and droplet manipulation.

Fluid manipulation is an important foundation of microfluidic technology. Various methods and devices have been developed for fluid control, such as electrowetting-on-dielectric-based digital microfluidic platforms, microfluidic pumps, and pneumatic valves. These devices enable precise manipulation of small volumes of fluids. However, their complexity and high cost limit the commercialization and widespread adoption of microfluidic technology. Shape memory polymers as smart materials can adjust their shape in response to external stimuli. By integrating shape memory polymers into microfluidic chips, new possibilities for expanding the application areas of microfluidic technology emerge. These shape memory polymers can serve as actuators or regulators to drive or control fluid flow in microfluidic systems, offering innovative approaches for fluid manipulation. Due to their unique properties, shape memory polymers provide a new solution for the construction of intelligent and automated microfluidic systems. Shape memory microfluidic chips are expected to be one of the future directions in the development of microfluidic technology. This article offers a summary of recent research achievements in the field of shape memory microfluidic chips for fluid and droplet manipulation and provides insights into the future development direction of shape memory microfluidic devices.

Droplet pair breakup in microfluidic expansion channel

Previous studies on droplet splitting mainly focus on monodisperse droplets, and the understanding of the breakup of polydisperse droplet systems is still lacking. In this work, we experimentally study the breakup of droplet pairs in the expansion region of microfluidic channel. The results show that with the increase in the size ratio of the droplets in the droplet pair, the breakup mode of droplet pairs changes from rear droplet breakup to front droplet breakup, and then to front droplet alternate breakup. The expansion angle can affect the critical size ratio of the splitting mode transition, but it cannot change the transition trend. The expansion angle plays a major role in the splitting time and distance of the droplet pair. When the expansion angle is increased, the splitting time of the droplet pair is reduced and the splitting distance is shorter. Our study extends the understanding of the breakup of non-monodisperse droplet systems and provides a feasible approach for the selective and controllable splitting of droplets, which is important for laboratory-on-a-chip droplet volume manipulation and has potential applications.

Higher resistance training volume offsets muscle hypertrophy nonresponsiveness in older individuals.

The magnitude of muscle hypertrophy in response to resistance training (RT) is highly variable between individuals (response heterogeneity). Manipulations in RT variables may modulate RT-related response heterogeneity; yet, this remains to be determined. Using a within-subject unilateral design, we aimed to investigate the effects of RT volume manipulation on whole muscle hypertrophy [quadriceps muscle cross-sectional area (qCSA)] among nonresponders and responders to a low RT dose (single-set). We also investigated the effects of RT volume manipulation on muscle strength in these responsiveness groups. Eighty-five older individuals [41M/44F, age = 68 ± 4 yr; body mass index (BMI) = 26.4 ± 3.7 kg/m2] had one leg randomly allocated to a single (1)-set and the contralateral leg allocated to four sets of unilateral knee-extension RT at 8-15 repetition maximum (RM) for 10-wk 2 days/wk. Pre- and postintervention, participants underwent magnetic resonance imaging (MRI) and unilateral knee-extension 1-RM strength testing. MRI typical error (2× TE = 3.27%) was used to classify individuals according to responsiveness patterns. n = 51 were classified as nonresponders (≤2× TE) and n = 34 as responders (>2× TE) based on pre- to postintervention change qCSA following the single-set RT protocol. Nonresponders to single-set training showed a dose response, with significant time × set interactions for qCSA and 1-RM strength, indicating greater gains in response to the higher volume prescription (time × set: P < 0.05 for both outcomes). Responders improved qCSA (time: P < 0.001), with a tendency toward higher benefit from the four sets RT protocol (time × set: P = 0.08); on the other hand, 1-RM increased similarly irrespectively of RT volume prescription (time × set: P > 0.05). Our findings support the use of higher RT volume to mitigate nonresponsiveness among older adults.NEW & NOTEWORTHY Using a within-subject unilateral design, we demonstrated that increasing resistance training (RT) volume may be a simple, effective strategy to improve muscle hypertrophy and strength gains among older adults who do not respond to low-volume RT. In addition, it could most likely be used to further improve hypertrophic outcomes in responders.

Microfluidics in smart food safety.

The evolution of food safety practices is crucial in addressing the challenges posed by a growing global population and increasingly complex food supply chains. Traditional methods are often labor-intensive, time-consuming, and susceptible to human error. This chapter explores the transformative potential of integrating microfluidics into smart food safety protocols. Microfluidics, involving the manipulation of small fluid volumes within microscale channels, offers a sophisticated platform for developing miniaturized devices capable of complex tasks. Combined with sensors, actuators, big data analytics, artificial intelligence, and the Internet of Things, smart microfluidic systems enable real-time data acquisition, analysis, and decision-making. These systems enhance control, automation, and adaptability, making them ideal for detecting contaminants, pathogens, and chemical residues in food products. The chapter covers the fundamentals of microfluidics, its integration with smart technologies, and its applications in food safety, addressing the challenges and future directions in this field.

Next generation microfluidics: fulfilling the promise of lab-on-a-chip technologies.

Microfluidic lab-on-a-chip technologies enable the analysis and manipulation of small fluid volumes and particles at small scales and the control of fluid flow and transport processes at the microscale, leading to the development of new methods to address a broad range of scientific and medical challenges. Microfluidic and lab-on-a-chip technologies have made a noteworthy impact in basic, preclinical, and clinical research, especially in hematology and vascular biology due to the inherent ability of microfluidics to mimic physiologic flow conditions in blood vessels and capillaries. With the potential to significantly impact translational research and clinical diagnostics, technical issues and incentive mismatches have stymied microfluidics from fulfilling this promise. We describe how accessibility, usability, and manufacturability of microfluidic technologies should be improved and how a shift in mindset and incentives within the field is also needed to address these issues. In this report, we discuss the state of the microfluidic field regarding current limitations and propose future directions and new approaches for the field to advance microfluidic technologies closer to translation and clinical use. While our report focuses on using blood as the prototypical biofluid sample, the proposed ideas and research directions can be extrapolated to other areas of hematology, oncology, biology, and medicine.

Highly complex liver resections: Exploring the boundaries of feasibility and safety.

In select clinical scenarios, advanced techniques for volume manipulation and vascular reconstruction are needed for complete hepatic tumor removal. These highly complex liver resections (HCLRs) entail a heightened risk of severe complications. Here, we describe the results of HCLR performed in a 3-year time period. We conducted a retrospective analysis encompassing patients who underwent hepatic resections between June 15, 2020, and June 15, 2023. HCLR was defined according to previously established criteria, and included associating liver partition and portal vein ligation for staged hepatectomy.The outcomes of HCLR were compared to all non-HCLR performed within the same time frame. Among 167 hepatic resections, 26 were considered HCLR, and all were major resections. Five utilized total vascular exclusion, with venovenous bypassin three, and hypothermic liver perfusion in three. Five resections included vascular reconstructions, and one included hypothermic circulatory arrest for extraction of a tumor extending to the right atrium. Of the non-HCLR, 38 (26.9%) were major, and 49 (34.7%) were performed laparoscopically. The rates of overall major postoperative complications were comparable between those who underwent HCLR versus non-HCLR. HCLR was associated with increased rates of biliary complications, readmissions, and reoperation. However, no postoperative 90-day mortality was documented within patients that underwent HCLR compared to two in the non-HCLR group. In expert hands, HCLR can be performed with acceptable complication profile, akin to that of major non-HCLR. Those with questionable resectability should be referred to tertiary hepato-pancreato-biliary centers.

Magnetic Microtweezers for High-Throughput Bioseparation in Sub-Nanoliter Droplets.

Multiomics studies at single-cell level require small volume manipulation, high throughput analysis, and multiplexed detection, characteristics that droplet microfluidics can tackle. However, the initial step of molecule bioseparation remains challenging. Here, we describe a unique magnetic device to trap and extract magnetic particles in sub-nanoliter droplets, for compartmentalisation of detection steps. Relying on electrodeposition of NiFe structures and microfluidic manipulation, the extraction of 1μm diameter magnetic particles was achieved at high throughput (20 droplets per second) with an efficiency close to 100% in 450 pL droplets. The first demonstration of its adaptability to single-cell analysis is demonstrated with the extraction of mRNA. Using a purified nucleic acid solution, this unique magnetic configuration was able to reach a RNA extraction rate of 72%. This is the first demonstration of a physical separation in droplets at high throughput at single-cell scale.

HPB P19 Post-hepatectomy liver failure: A timeline centered review

Abstract Background Post-hepatectomy liver failure (PHLF) is a leading cause of postoperative mortality after liver surgery. Due to its significant impact, it is imperative to understand the risk stratification and preventative strategies for PHLF. Whilst the literature addressing PHLF appears ubiquitous, there is no specific structure that summarizes the evidence that can guide surgeons regarding the timeline of the preventive measures against PHLF. The objective of this review is to summarize the published measures and their sources of evidence, in a timeline centered way around the index (i.e., definitive) hepatectomy, thus, summarizing the practice in prediction, prevention, and treatment. Methods This review includes studies on both humans and animals, where they addressed PHLF. A literature search was conducted across the Cochrane Library, Embase, MEDLINE/PubMed, and Web of Knowledge electronic databases for English language studies published between July 1997 and June 2020. Studies presented in other languages were equally considered. The quality of included publications was assessed using Downs and Black’s checklist. The results were presented in qualitative summaries owing to the lack of studies qualifying for quantitative analysis. Results This systematic review with 245 studies, provides insight into the current prediction, prevention, diagnosis, and management options for PHLF. This review highlighted that liver volume manipulation is the most frequently studied preventive measure against PHLF in clinical practice, with modest improvement in the treatment strategies over the past decade. Conclusions Remnant liver volume manipulation is the most consistent preventive measure against PHLF.

Microneurocirugía intrauterina para la corrección de espina bífida congénita: primer caso exitoso reportado en Venezuela

Congenital spina bifida is a malformation of the central nervous system that occurs during embryological development. Its etiology is multifactorial and it is estimated that it affects 1:1500 pregnancies, in which motor and sensory deficits, secondary to spinal cord injury, hydrocephalus and Arnold-Chiari II malformation are the most significant findings. Prenatal surgical treatment has been described through the open approach, microneurosurgery, and fetoscopic resolution, with well-known advantages and disadvantages, but which invariably improve postnatal prognosis and the severity of neurological sequelae, as well as the need for ventriculoperitoneal shunt. We present the first case of open microneurosurgery for intrauterine repair of myelomeningocele performed in Venezuela, a novel technique characterized by a minimum uterine incision of 20-30 mm, reduced fetal manipulation and maintenance of a normal volume of amniotic fluid throughout the process, in a patient at 24 weeks of gestation.

Sub-5-Minute Ultrafast PCR using Digital Microfluidics

The development of a rapid and reliable polymerase chain reaction (PCR) method for point-of-care (POC) diagnosis is crucial for the timely identification of pathogens. Microfluidics, which involves the manipulation of small volumes of fluidic samples, has been shown to be an ideal approach for POC analysis. Among the various microfluidic platforms available, digital microfluidics (DMF) offers high degree of configurability in manipulating μL/nL-scale liquid and achieving automation. However, the successful implementation of ultrafast PCR on DMF platforms presents challenges due to inherent system instability. In this study, we developed a robust and ultrafast PCR in 3.7–5 min with a detection sensitivity comparable to conventional PCR. Specifically, the implementation of the pincer heating scheme homogenises the temperature within a drop. The utilization of a μm-scale porous hydrophobic membrane suppresses the formation of bubbles under high temperatures. The design of a groove around the high-temperature zone effectively mitigates the temperature interference. The integration of a soluble sensor into the droplets provides an accurate and instant in-drop temperature sensing. We envision that the fast, robust, sensitive, and automatic DMF system will empower the POC testing for infectious diseases.

Computational and experimental investigations of a microfluidic mixer for efficient iodine extraction using carbon tetrachloride enhanced with gas bubbles

Numerous studies have been conducted on microfluidic mixers in various microanalysis systems, which elucidated the manipulation and control of small fluid volumes within microfluidic chips. These studies have demonstrated the ability to control fluids and samples precisely at the microscale. Microfluidic mixers provide high sensitivity for biochemical analysis due to their small volumes and high surface-to-volume ratios. A promising approach in drug delivery is the rapid microfluidic mixer-based extraction of elemental iodine at the micro level, demonstrating the versatility and the potential to enhance diagnostic imaging and accuracy in targeted drug delivery. Micro-mixing inside microfluidic chips plays a key role in biochemical analysis. The experimental study describes a microfluidic mixer for extraction of elemental iodine using carbon tetrachloride with a gas bubble mixing process. Gas bubbles are generated inside the microcavity to create turbulence and micro-vortices resulting in uniform mixing of samples. The bubble mixing of biochemical samples is analyzed at various pressure levels to validate the simulated results in computational fluid dynamics (CFD). The experimental setup includes a high-resolution camera and an air pump to observe the mixing process and volume at different pressure levels with time. The bubble formation is controlled by adjusting the inert gas flow inside the microfluidic chip. Microfluidic chip-based gas bubble mixing effects have been elaborated at various supplied pressures.

A Miniaturized Archimedean Screw Pump for High-Viscosity Fluid Pumping in Microfluidics.

Microfluidic devices have revolutionized the field of lab-on-a-chip by enabling precise manipulation of small fluid volumes for various biomedical applications. However, most existing microfluidic pumps struggle to handle high-viscosity fluids, limiting their applicability in certain areas that involve bioanalysis and on-chip sample processing. In this paper, the design and fabrication of a miniaturized Archimedean screw pump for pumping high-viscosity fluids within microfluidic channels are presented. The pump was 3D-printed and operated vertically, allowing for continuous and directional fluid pumping. The pump's capabilities were demonstrated by successfully pumping polyethylene glycol (PEG) solutions that are over 100 times more viscous than water using a basic mini-DC motor. Efficient fluid manipulation at low voltages was achieved by the pump, making it suitable for point-of-care and field applications. The flow rates of water were characterized, and the effect of different screw pitch lengths on the flow rate was investigated. Additionally, the pump's capacity for pumping high-viscosity fluids was demonstrated by testing it with PEG solutions of increasing viscosity. The microfluidic pump's simple fabrication and easy operation position it as a promising candidate for lab-on-a-chip applications involving high-viscosity fluids.

Broadband microwave antenna for uniform manipulation of millimeter-scale volumes of diamond quantum sensors

Quantum sensors based on nitrogen-vacancy (NV) centers in diamond are expected to demonstrate a wide variety of applications. For high-sensitivity quantum sensors with NV center ensembles, uniform manipulation of the electron spins of the NV centers in large volumes is required. In addition, a broad microwave frequency bandwidth for manipulating the NV centers' electron spin is necessary for vector magnetometry and measurement under a finite static magnetic field. Here, we demonstrate a broadband microwave antenna for uniform manipulation of millimeter-scale volumes of diamond quantum sensors. The simulation shows that the current is distributed at both edges of the loop coil of a single copper plate due to the skin effect. The loop coil acts like a Helmholtz coil, which realizes uniformity in the z-direction of the microwave magnetic field (B1). The plate structure has a higher mechanical stability, durability, and a larger heat capacity than the Helmholtz coil, due to its large volume. The antenna achieves a higher performance than previously reported antennae, with a maximal B1 of 4.5 G, a broad bandwidth of 287 ± 6 MHz, and a peak-to-peak variation of 9.2% over a 3.1 mm3 cylinder volume. These performances show that the presented antenna is suitable for manipulating solid-state spin ensembles for high-sensitivity quantum sensors.

Confined Nanopipet as a Versatile Tool for Precise Single Cell Manipulation.

The precise manipulation of single cells plays a fundamental role for single cell measurement, which is crucial for understanding the diverse cellular mechanisms. Unusual single cell behavior could thus be identified by integrating with advanced analytical methods such as single cell omics, unraveling the intrinsic cellular heterogeneity hidden in ensemble measurements. Herein, this technical note reports a nanopipet-based versatile method for manipulation of an ultrasmall volume of liquid, which further enables the precise manipulation of single cells. Femtoliter volumes of cytoplasm were extracted from single living cells and analyzed by time-of-flight secondary ion mass spectrometry. Moreover, several kinds of exogenous components were injected simultaneously into a cell, offering a delicate tool for multi-imaging in single living cells.

Reproducibility of assessment of full-dilatation Cesarean section scar in women undergoing second-trimester screening for preterm birth.

ABSTRACTObjectiveTo assess the reproducibility of a standardized method of measuring the Cesarean section (CS) scar, CS scar niche and their position relative to the internal os of the uterine cervix by transvaginal ultrasound in pregnant women with a previous full‐dilatation CS.MethodsThis was a prospective, single‐center reproducibility study on women with a singleton pregnancy and a previous full‐dilatation CS who underwent transvaginal ultrasound assessment of cervical length and CS scar characteristics at 14–24 weeks' gestation. The CS scar was identified as a hypoechogenic linear discontinuity of the myometrium at the anterior wall of the lower uterine segment or cervix. The CS scar niche was identified as an indentation at the site of the scar with a depth of at least 2 mm. The CS scar position was evaluated by measuring the distance to the internal cervical os. CS scar niche parameters, including its length, depth, width, and residual and adjacent myometrial thickness, were assessed in the sagittal and transverse planes. Qualitative reproducibility was assessed by agreement regarding visibility of the CS scar and niche. Quantitative reproducibility of CS scar measurements was assessed using three sets of images: (1) real‐time two‐dimensional (2D) images (real‐time acquisition and caliper placement on 2D images by two operators), (2) offline 2D still images (offline caliper placement by two operators on stored 2D images acquired by one operator) and (3) three‐dimensional (3D) volume images (volume manipulation and caliper placement on 2D images extracted by two operators). Agreement on CS scar visibility and the presence of a niche was analyzed using kappa coefficients. Intraobserver and interobserver reproducibility of quantitative measurements was assessed using Bland–Altman plots.ResultsTo achieve the desired statistical power, 72 women were recruited. The CS scar was visualized in > 80% of images. Interobserver agreement for scar visualization and presence of a niche in real‐time 2D images was excellent (kappa coefficients of 0.84 and 0.85, respectively). Overall, reproducibility was higher for real‐time 2D and offline 2D still images than for 3D volume images. The 95% limits of agreement (LOA) for intraobserver reproducibility were between ± 1.1 and ± 3.6 mm for all sets of images; the 95% LOA for interobserver reproducibility were between ± 2.0 and ± 6.3 mm. Measurement of the distance from the CS scar to the internal cervical os was the most reproducible 2D measurement (intraobserver and interobserver 95% LOA within ± 1.6 and ± 2.7 mm, respectively). Overall, niche measurements were the least reproducible measurements (intraobserver 95% LOA between ± 1.6 and ± 3.6 mm; interobserver 95% LOA between ± 3.1 and ± 6.3 mm). There was no consistent difference between measurements obtained by reacquisition of 2D images (planes obtained twice and caliper placed), caliper placement on 2D stored images or volume manipulation (planes obtained twice and caliper placed).ConclusionsThe CS scar position and scar niche in pregnant women with a previous full‐dilatation CS can be assessed in the second trimester of a subsequent pregnancy using either 2D or 3D volume ultrasound imaging with a high level of reproducibility. Overall, the most reproducible CS scar parameter is the distance from the CS scar to the internal cervical os. The method proposed in this study should enable clinicians to assess the CS scar reliably and may help predict pregnancy outcome. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.