Detection Rate and Clinical Relevance of Ink Tattooing during Balloon-Assisted Enteroscopy

Background and Aims. Balloon-assisted enteroscopy (BAE) is a well-established tool in the diagnosis and therapy of small bowel diseases. Ink tattooing of the small bowel is used to mark pathologic lesions or the depth of small bowel insertion. The purpose of this study was to determine the safety, the detection rate, and the clinical relevance of ink tattooing during BAE. Methods. We performed a retrospective analysis of all 81 patients who received an ink tattooing during BAE between 2010 and 2015. Results. In all patients, ink tattooing was performed with no complications. 26 patients received a capsule endoscopy after BAE. The tattoo could be detected via capsule endoscopy in 19 of these 26 patients. The tattoo of the previous BAE could be detected via opposite BAE in 2 of 11 patients. In 9 patients, ink tattooing influenced the choice of approach for reenteroscopy. In 7 patients, the tattoo was used for intraoperative localization and in 3 patients for intraoperative localization as well as for reenteroscopy. The intraoperative detection rate of the tattoo was 100%. Conclusion. Ink tattooing of the small intestine is a safe endoscopic procedure to mark the depth of scope insertion or a pathologic lesion during balloon-assisted enteroscopy

Inclusion-based effective medium models for the permeability of a 3D fractured rock mass

Effective permeability is an essential parameter for describing fluid flow through fractured rock masses. This study investigates the ability of classical inclusion-based effective medium models (following the work of Sævik et al. in Transp Porous Media 100(1):115–142, 2013. doi:10.1007/s11242-013-0208-0) to predict this permeability, which depends on several geometric properties of the fractures/networks. This is achieved by comparison of various effective medium models, such as the symmetric and asymmetric self-consistent schemes, the differential scheme, and Maxwell’s method, with the results of explicit numerical simulations of mono- and poly-disperse isotropic fracture networks embedded in a permeable rock matrix. Comparisons are also made with the Hashin–Shtrikman bounds, Snow’s model, and Mourzenko’s heuristic model (Mourzenko et al. in Phys Rev E 84:036–307, 2011. doi:10.1103/PhysRevE.84.036307). This problem is characterised by two small parameters, the aspect ratio of the spheroidal fractures, α, and the ratio between matrix and fracture permeability, κ. Two different regimes can be identified, corresponding to α/κ1. The lower the value of α/κ, the more significant is flow through the matrix. Due to differing flow patterns, the dependence of effective permeability on fracture density differs in the two regimes. When α/κ≫1, a distinct percolation threshold is observed, whereas for α/κ≪1, the matrix is sufficiently transmissive that such a transition is not observed. The self-consistent effective medium methods show good accuracy for both mono- and polydisperse isotropic fracture networks. Mourzenko’s equation is very accurate, particularly for monodisperse networks. Finally, it is shown that Snow’s model essentially coincides with the Hashin–Shtrikman upper bound.ISSN:0169-3913ISSN:1573-163