Laparoscopic adhesiolysis: consensus conference guidelines.

AIM: Laparoscopic adhesiolysis has been demonstrated to be technically feasible in small bowel obstruction and carries advantages in terms of post-surgical course. The increasing dissemination of laparoscopic surgery in the emergency setting and the lack of concrete evidence in the literature have called for a consensus conference to draw recommendations for clinical practice. METHODS: A literature search was used to outline the evidence, and a consensus conference was held between experts in the field. A survey of international experts added expertise to the debate. A public jury of surgeons discussed and validated the statements, and the entire process was reviewed by three external experts. RESULTS: Recommendations concern the diagnostic evaluation, the timing of the operation, the selection of patients, the induction of the pneumoperitoneum, the removal of the cause of obstructions, the criteria for conversion, the use of adhesion-preventing agents, the need for high-technology dissection instruments and behaviour in the case of misdiagnosed hernia or the need for bowel resection. CONCLUSION: Evidence of this kind of surgery is scanty because of the absence of randomized controlled trials. Nevertheless laparoscopic skills in emergency are widespread. The recommendations given with the consensus process might be a useful tool in the hands of surgeons.

Reversine increases multipotent human mesenchymal cells differentiation potential.

Among different human stem cell sources, adult mesenchymal stem cells from bone marrow (BMSCs), and more recently from adipose tissues (ASCs), have shown their capability to differentiate into a variety of different cell types, including osteoblasts, adipocytes, and muscle cells. However, mesenchymal stem cell differentiation toward certain cell types (including skeletal and cardiac muscle), while shown to be achievable, still suffers of low yields and needs to be greatly improved before any therapeutic application could be foreseen. A possible way of achieving this goal is by using a chemical-pharmacological approach to increase stem cell plasticity. Along this line, we envisioned the possibility of pre-treating BMSCs and ASCs with reversine, a synthetic purine that has been shown to induce adult cells de-differentiation. In the current study we tested reversine effects on both BMSCs and ASCs to increase their differentiation toward osteoblasts, smooth and skeletal muscle cells. Reversine pre-treatment, at very low concentration (50 nM), caused a marked increase in the differentiation yields of both BMSCs and ASCs.

CD16-mediated p21ras activation is associated with Shc and p36 tyrosine phosphorylation and their binding with Grb2 in human natural killer cells.

The Src homology (SH) 2/SH3 domain-containing protein Grb2 and the oncoprotein Shc have been implicated in a highly conserved mechanism that regulates p21ras activation. We investigated the involvement of these adaptor proteins in the signaling pathway induced by CD16 or interleukin (IL) 2R triggering in human natural killer (NK) cells. Both p46 and p52 forms of Shc were rapidly and transiently tyrosine phosphorylated upon CD16 or IL-2 stimulation with different kinetics. Shc immunoprecipitates from lysates of CD16- or IL-2-stimulated NK cells contained Grb2 and an unidentified 145-kD tyrosine phosphoprotein. Grb2 immunoprecipitates from anti-CD16-stimulated NK cells contained not only Shc, but also a 36-kD tyrosine phosphoprotein (p36). The interaction between Grb2 and Shc or p36 occurred via the Grb2SH2 domain as indicated by in vitro binding assays using a bacteriologically synthesized glutathione S-transferase-Grb2SH2 fusion protein. We also present evidence that p21ras is activated by CD16 and IL-2R cross-linking. Accumulation of guanosine triphosphate-bound Ras was detected within 1 minute and occurred with kinetics similar to inductive protein tyrosine phosphorylation and Grb2 association of Shc and p36 adaptor proteins.

Triggering through CD16 or phorbol esters enhances adhesion of NK cells to laminin via very late antigen 6.

Very late antigens VLA-1, VLA-2, VLA-3, and VLA-6, belonging to the beta 1 subfamily of integrins, have been identified as receptors for different binding domains of laminin (LM). We have detected VLA-6, but not VLA-1 and VLA-2 on a subset (50-70%) of fresh peripheral blood CD3-, CD16+, CD56+ human natural killer (NK) cells by immunofluorimetric and biochemical analysis. Binding assays performed on LM-coated plates showed that 10-15% of NK cells spontaneously adhere to LM, and this adhesion is mediated by VLA-6. Activation of NK cells through CD16 triggering or by phorbol ester results in a rapid increase of adhesion to LM, which is still mediated by VLA-6. The enhanced adhesiveness is not associated with changes in beta 1 LM receptor expression, while it correlates with changes in the phosphorylation status of alpha 6 subunit. The expression of VLA-6 on NK cells and the modulation of its avidity by activating stimuli may be relevant for NK cell migration and tissue location during inflammation or immune response.

Integrin-mediated ras-extracellular regulated kinase (ERK) signaling regulates interferon gamma production in human natural killer cells.

Recent evidence indicates that integrin engagement results in the activation of biochemical signaling events important for regulating different cell functions, such as migration, adhesion, proliferation, differentiation, apoptosis, and specific gene expression. Here, we report that beta1 integrin ligation on human natural killer (NK) cells results in the activation of Ras/mitogen-activated protein kinase pathways. Formation of Shc-growth factor receptor-bound protein 2 (Grb2) and Shc-proline-rich tyrosine kinase 2-Grb2 complexes are the receptor-proximal events accompanying the beta1 integrin-mediated Ras activation. In addition, we demonstrate that ligation of beta1 integrins results in the stimulation of interferon gamma (IFN-gamma) production, which is under the control of extracellular signal-regulated kinase 2 activation. Overall, our data indicate that beta1 integrins, by delivering signals capable of triggering IFN-gamma production, may function as NK-activating receptors.

Increased adipogenic conversion of muscle satellite cells in obese Zucker rats.

AIMS/HYPOTHESIS: Visceral and intermuscular adipose tissue (IMAT) depots account for most obesity-related metabolic and cardiovascular complications. Muscle satellite cells (SCs) are mesenchymal stem cells giving rise to myotubes and also to adipocytes, suggesting their possible contribution to IMAT origin and expansion. We investigated the myogenic differentiation of SCs and the adipogenic potential of both preadipocytes and SCs from genetically obese Zucker rats (fa/fa), focusing on the role of Wnt signaling in these differentiation processes. METHODS: SCs were isolated by single-fiber technique from flexor digitorum brevis muscle and preadipocytes were extracted from subcutaneous adipose tissue (AT). Morphological features and gene expression profile were evaluated during in vitro myogenesis and adipogenesis. Wingless-type MMTV integration site family member 10b (Wnt10b) expression was quantified by quantitative PCR in skeletal muscle and AT. RESULTS: We did not observe any difference in the proliferation rate and in the myogenic differentiation of SCs from obese and lean rats. However, a decreased insulin-induced glucose uptake was present in myotubes originating from fa/fa rats. Under adipogenic conditions, preadipocytes and SCs of obese animals displayed an enhanced adipogenesis. Wnt10b expression was reduced in obese rats in both muscle and AT. CONCLUSIONS/INTERPRETATION: Our data suggest that the increase in different fat depots including IMAT and the reduced muscle insulin sensitivity, the major phenotypical alteration of obese Zucker rats, could be ascribed to an intrinsic defect, either genetically determined or acquired, still present in both muscle and fat precursors. The involvement of Wnt10b as a regulator of both adipogenesis and muscle-to-fat conversion is suggested.

Gestational diabetes and fetal growth acceleration: induction of labour versus expectant management.

AIM: The aim of the study was to compare elective induction of labour at 38 weeks versus expectant management in A1 and A2 gestational diabetes (GDM) pregnancies with fetal growth acceleration. Primary outcome of the study was C-section (CS) rate, while secondary outcomes were macrosomia incidence and adverse perinatal outcomes. METHODS: A retrospective cohort study was carried out. Data were collected between 1996 and 2006 and evaluated through patients' records analysis. Differences between the two study groups were investigated using non-parametric tests for continuous variables and χ2 test for categorical ones. RESULTS: There was no significant difference between induction and expectant management in terms of caesarean section rate. A trend favoring women in the induction group in terms of incidence of macrosomia and neonatal outcomes was identified, but results were not statistically significant. CONCLUSION: Labour induction at 38 weeks in GDM patients with fetal growth acceleration does not seem to determine an increased incidence of C-section in comparison to expectant management, particularly in case of maternal obesity.

[Ethical approach to the issue of confinement of the elderly in the context of the COVID-19 pandemic: Prevention of frailty versus risk of vulnerability]. / Une approche éthique de la question du confinement des personnes âgées en contexte de pandémie COVID-19 : la prévention des fragilités face au risque de vulnérabilité.

COVID-19 pandemic particularly affects older people and exposes them to a higher risk of mortality. Containment, social distancing and isolation measures have been implemented to limit viral transmission. While there is a clear rationale for reducing the contagiousness of the infection through this means, the adverse consequences of this social isolation, especially for this heterogeneous, aged and frail people, are difficult to apprehend. In particular, the disruption of the usual support and care ecosystems at home or in institutions may paradoxically increase the frailty of these people and lead to adverse events we wanted to avoid. On the other hand, the risk of a decrease in the older person's empowerment regarding his or her own health and social life decisions requires particular vigilance to prevent the risk of societal ageism. Regarding this population in particular, a possible conflict of values between individual and collective protection on one hand and respect for autonomy and independence on the other hand could exist. This article proposes an ethical reflection on the issue of containment of frail ageing people, based on medical ethics principles, in order to open up positive approaches of vulnerability that guarantee respect for the dignity of the person and equity in care access.

Analysis of resorbable mesh implants in short-term human muscular fascia cultures: a pilot study.

PURPOSE: Alteration in fascial tissue collagen composition represents a key factor in hernia etiology and recurrence. Both resorbable and non-resorbable meshes for hernia repair are currently used in the surgical setting. However, no study has investigated so far the role of different implant materials on collagen deposition and tissue remodeling in human fascia. The aim of the present study was to develop a novel ex vivo model of human soft tissue repair mesh implant, and to test its suitability to investigate the effects of different materials on tissue remodeling and collagen composition. METHODS: Resorbable poly-4-hydroxybutyrate and non-resorbable polypropylene mesh implants were embedded in human abdominal fascia samples, mimicking common surgical procedures. Calcein-AM/Propidium Iodide vital staining was used to assess tissue vitality. Tissue morphology was evaluated using Mallory trichrome and hematoxylin and eosin staining. Collagen type I and III expression was determined through immunostaining semi-quantification by color deconvolution. All analyses were performed after 54 days of culture. RESULTS: The established ex vivo model showed good viability at 54 days of culture, confirming both culture method feasibility and implants biocompatibility. Both mesh implants induced a disorganization of collagen fibers pattern. A statistically significantly higher collagen I/III ratio was detected in fascial tissue samples cultured with resorbable implants compared to either non-resorbable implants or meshes-free controls. CONCLUSION: We developed a novel ex vivo model and provided evidence that resorbable polyhydroxybutyrate meshes display better biomechanical properties suitable for proper restoration in surgical hernia repair.

Mid-transverse colon cancer and extended versus transverse colectomy: Results of the Italian society of surgical oncology colorectal cancer network (SICO CCN) multicenter collaborative study.

INTRODUCTION: Transverse colon cancer (TCC) is poorly studied, and TCC cases are often excluded from large prospective randomized trials because of their complexity and their potentially high complication rate. The best surgical approach for TCC has yet to be established. The aim of this large retrospective multicenter Italian series is to investigate the advantages and disadvantages of both hemicolectomy and transverse colectomy in order to identify the best surgical approach. MATERIALS AND METHODS: This was a retrospective cohort study of patients with mid-transverse colon cancer treated with a segmental colon resection or an extended hemicolectomy (right or left) between 2006 and 2016 in 28 high-volume (more than 70 procedures/year) Italian referral centers for colorectal surgery. RESULTS: The study included 1529 patients, 388 of whom underwent a segmental resection while 1141 underwent an extended resection. A higher number of complications has been reported in the segmental group than in the extended group (30.1% versus 23.6%; p 0.010). In 42 cases the main complication was the anastomotic leak (4.4% versus 2.2%; p 0.020). Recovery outcomes also showed statistical differences: time to first flatus (p 0.014), time to first mobilization (p 0.040), and overall hospital stay (p < 0.001) were significantly shorter in the extended group. Even if overall survival were similar between the groups (95.1% versus 97%; p 0.384), 3-year disease-free survival worsened after segmental resection (78.1% versus 86.2%; p 0.001). CONCLUSIONS: According to our results, an extended right colon resection for TCC seems to be surgically safer and more oncologically valid.

[Diagnostic, therapeutic and healthcare management protocols in thyroid surgery. 2nd Consensus Conference (U.E.C. CLUB)]. / Protocolli Gestionali Diagnostico-Terapeutico-Assistenziali in Chirurgia Tiroidea. 2 feminine Consensus Conference.

AIM: To review and to update the management protocols in thyroid surgery proposed two years ago by 1st Consensus Conference called on the topic by the Italian Association of Endocrine Surgery Units (UEC Club). METHOD: The 2nd Consensus Conference took place November 30, 2008 in Pisa within the framework of the 7th National Congress of the UEC Club. A selected board of endocrinologists and endocrine surgeons (chairmans: Paolo Miccoli and Aldo Pinchera; speaker: Lodovico Rosato) examined the individual chapters and submitted the consensus text for the approval of several experts. This plain and concise text provides the rationale of the thyroid patient management and wants to be the most complete possible tool for the physicians and other professionals in the field. CONCLUSIONS: The diagnostic, therapeutic and healthcare management protocols in thyroid surgery approved by the 2nd Consensus Conference are officially those proposed by the Italian Association of Endocrine Surgery Units (UEC Club) and are subject to review by two years.

Synchrotron Radiation Applied to Real-Time Studies of the Kinetics of Growth of Aluminum Nitride Thin Multilayers.

This article reports the design, construction, and first use of an experimental device consisting of a specially designed vacuum chamber equipped with a reactive sputtering magnetron (RSM) to be used for controlled deposition of thin films on a Si(100) flat substrate. The setup was designed to allow for in situ and real-time recordings of X-ray diffraction patterns during the growth of the deposited films and was installed in the X-ray diffraction and spectroscopy beamline emerging from a superconducting wiggler source at the Brazilian Synchrotron Light Laboratory. The first use of the RSM setup was an in situ and real-time X-ray diffraction study of processes of growth of multilayered aluminum nitride thin films, whereas the operation parameters of the reactor were sequentially changed. This sequential process led to the development of multilayered films. Alternate variations in chamber pressure and magnetron power density allowed us to obtain thin films composed of several micrometer thick layers, with alternate amorphous and (10·0), (00·2), or (10·1) textured polycrystalline structures.

The proton pump interactor (Ppi) gene family of Arabidopsis thaliana: expression pattern of Ppi1 and characterisation of knockout mutants for Ppi1 and 2.

Plant plasma membrane H+-ATPases (PM H+-ATPase) are essential for establishing a proton electrochemical gradient across the cell plasma membrane. Their regulation is poorly understood, except for the role of 14-3-3 proteins, which relieve autoinhibition from the C-terminal domain. A novel protein interacting with this domain was recently identified in Arabidopsis and named PPI1 (Proton Pump Interactor 1). PPI1 stimulates PM H+-ATPase activity in vitro. Here, we analyse the expression pattern of Ppi1 using beta-glucuronidase as a reporter. Expression is strong in root and shoot vascular systems, particularly in meristematic and sink tissues, as well as in pollen, stigmas and siliques, but not in developing embryos. Removal of the first intron decreased GUS expression 45-fold. We also analysed the transcription of Ppi2, another gene in the family, and demonstrated that Ppi2 is expressed in seedlings, cultured cells and flowers. We reassessed Ppi2 gene structure based on RT-PCR amplifications, cDNA data and similarity to other Ppi genes. Insertional mutants for both Ppi1 and Ppi2 were isolated. Two different mutants of Ppi1 showed aberrant mRNAs and lacked any detectable protein and are therefore true knockouts. Interestingly, one mutation inhibited the splicing of one intron at a considerable distance (>700 bp) from the T-DNA insertion site, but not the splicing of a proximal intron (29 bp) or of any other intron. At the plant level, neither of the single mutants nor the double ppi1ppi2 mutant showed an altered phenotype in standard growth conditions under acid load or salt stress.

A finite element analysis of diaphragmatic hernia repair on an animal model.

The diaphragm is a mammalian skeletal muscle that plays a fundamental role in the process of respiration. Alteration of its mechanical properties due to a diaphragmatic hernia contributes towards compromising its respiratory functions, leading to the need for surgical intervention to restore the physiological conditions by means of implants. This study aims to assess via numerical modeling biomechanical differences between a diaphragm in healthy conditions and a herniated diaphragm surgically repaired with a polymeric implant, in a mouse model. Finite Element models of healthy and repaired diaphragms are developed from diagnostic images and anatomical samples. The mechanical response of the diaphragmatic tendon is described by assuming an isotropic hyperelastic model. A similar constitutive model is used to define the mechanical behavior of the polymeric implant, while the muscular tissue is modeled by means of a three-element Hill's model, specifically adapted to mouse muscle fibers. The Finite Element Analysis is addressed to simulate diaphragmatic contraction in the eupnea condition, allowing the evaluation of diaphragm deformation in healthy and herniated-repaired conditions. The polymeric implant reduces diaphragm excursion compared to healthy conditions. This explains the possible alteration in the mechanical functionality of the repaired diaphragm. Looking to the surgical treatment of diaphragmatic hernia in human neonatal subjects, this study suggests the implementation of alternative approaches based on the use of biological implants.

Synthesis and chemical characterization of several perfluorinated sialic acid glycals and evaluation of their in vitro antiviral activity against Newcastle disease virus.

Newcastle Disease Virus (NDV), belonging to the Paramyxoviridae family, causes a serious infectious disease in birds, resulting in severe losses in the poultry industry every year. Haemagglutinin neuraminidase glycoprotein (HN) has been recognized as a key protein in the viral infection mechanism, and its inhibition represents an attractive target for the development of new drugs based on sialic acid glycals, with the 2-deoxy-2,3-didehydro-d-N-acetylneuraminic acid (Neu5Ac2en) as their backbone. Herein we report the synthesis of several Neu5Ac2en glycals and of their perfluorinated C-5 modified derivatives, including their respective stereoisomers at C-4, together with evaluation of their in vitro antiviral activity. While all synthesized compounds were found to be active HN inhibitors in the micromolar range, we found that their potency was influenced by the chain-length of the C-5 perfluorinated acetamido functionality. Thus, the binding modes of the inhibitors were also investigated by performing a docking study. Moreover, the perfluorinated glycals were found to be more active than the corresponding normal C-5 acylic derivatives. Finally, cell-cell fusion assays on NDV infected cells revealed that the addition of a newly synthesized C-4α heptafluorobutyryl derivative almost completely inhibited NDV-induced syncytium formation.

Diffusion MRI for rectal cancer staging: ADC measurements before and after ultrasonographic gel lumen distension.

OBJECTIVES: To compare Apparent Diffusion Coefficient (ADC) measurements in rectal neoplastic lesions before and after lumen distension obtained with sonography transmission gel. METHODS: From January 2014 to July 2016, 25 patients (average age 63.7, range 41-85, 18 males) were studied for pre-treatment rectal cancer staging using a 1.5T MRI. Diffusion MRI was obtained using echo-planar imaging with b=800 value; all patients were studied acquiring diffusion sequences with and without rectal lumen distension obtained using sonography transmission gel. In both diffusion sequences, two blinded readers calculated border ADC values and small ADC values, drawing regions of interest respectively along tumour borders and far from tumour borders. Mean ADC values among readers - for each type of ADC measurement - were compared using Wilcoxon matched pairs signed rank test. Correlation was assessed using Pearson analysis. RESULTS: Border ADC mean value for diffusion MR sequences without endorectal contrast was 1.122mm2/sec, with 95% Confidence Interval (CI)=1.02-1.22; using gel lumen distension, higher border ADC mean value of 1.269mm2/s (95% CI=1.16-1.38) was obtained. Wilcoxon matched pairs signed rank test revealed statistical difference (p<0.01); a strong Pearson correlation was reported, with r value of 0.69. Small-ADC mean value was 1.038mm2/s (95% CI=0.91-1.16) for diffusion sequences acquired without endorectal distension and 1.127mm2/s (95% CI=0.98-1.27) for diffusion sequences obtained after endorectal gel lumen distension. Wilcoxon analysis did not show statistical difference (p=0.13). A very strong positive correlation was observed, with r value of 0.81. CONCLUSIONS: ADC measurements are slightly higher using endorectal sonographic transmission gel; ROI should be traced far from tumour borders, to minimize gel filled-pixel along the interface between lumen and lesion. Further studies are needed to investigate better reliability of ADC in rectal cancer MRI using sonographic gel intraluminal distension.

First steps to define murine amniotic fluid stem cell microenvironment.

Stem cell niche refers to the microenvironment where stem cells reside in living organisms. Several elements define the niche and regulate stem cell characteristics, such as stromal support cells, gap junctions, soluble factors, extracellular matrix proteins, blood vessels and neural inputs. In the last years, different studies demonstrated the presence of cKit+ cells in human and murine amniotic fluid, which have been defined as amniotic fluid stem (AFS) cells. Firstly, we characterized the murine cKit+ cells present both in the amniotic fluid and in the amnion. Secondly, to analyze the AFS cell microenvironment, we injected murine YFP+ embryonic stem cells (ESC) into the amniotic fluid of E13.5 wild type embryos. Four days after transplantation we found that YFP+ sorted cells maintained the expression of pluripotency markers and that ESC adherent to the amnion were more similar to original ESC in respect to those isolated from the amniotic fluid. Moreover, cytokines evaluation and oxygen concentration analysis revealed in this microenvironment the presence of factors that are considered key regulators in stem cell niches. This is the first indication that AFS cells reside in a microenvironment that possess specific characteristics able to maintain stemness of resident and exogenous stem cells.

Improvement of diaphragmatic performance through orthotopic application of decellularized extracellular matrix patch.

Muscle tissue engineering can provide support to large congenital skeletal muscle defects using scaffolds able to allow cell migration, proliferation and differentiation. Acellular extracellular matrix (ECM) scaffold can generate a positive inflammatory response through the activation of anti-inflammatory T-cell populations and M2 polarized macrophages that together lead to a local pro-regenerative environment. This immunoregulatory effect is maintained when acellular matrices are transplanted in a xenogeneic setting, but it remains unclear whether it can be therapeutic in a model of muscle diseases. We demonstrated here for the first time that orthotopic transplantation of a decellularized diaphragmatic muscle from wild animals promoted tissue functional recovery in an established atrophic mouse model. In particular, ECM supported a local immunoresponse activating a pro-regenerative environment and stimulating host muscle progenitor cell activation and migration. These results indicate that acellular scaffolds may represent a suitable regenerative medicine option for improving performance of diseased muscles.

Distinct thymocyte subsets express the vanilloid receptor VR1 that mediates capsaicin-induced apoptotic cell death.

Herein, we provide the first evidence on the capsaicin (CPS) receptor vanilloid receptor type-1 (VR1) by rat thymocytes, and its involvement in CPS-induced apoptosis. VR1 mRNA was identified by quantitative RT-PCR in CD5(+) thymocytes. By immunofluorescence and flow cytometry, we found that a substantial portion of CD5+ thymocytes, namely CD4+ and double negative (DN) cell subsets, express VR1 that was present on plasma membrane on discrete spots. By Western blot, VR1 protein was identified as a single band of 95 kDa. We also described that CPS could trigger two distinct pathways of thymocyte death, namely apoptosis and necrosis depending on the dose of CPS exposure. CPS-induced apoptosis involved intracellular free calcium (Ca2+) influx, phosphatidylserine exposure, mitochondrial permeability transmembrane pore (PTP) opening and mitochondrial transmembrane potential (Delta Psi m) dissipation leading to cytochrome c release, activation of caspase-9 and -3 and oligonucleosomal DNA fragmentation. VR1 was functionally implicated in these events as they were completely abrogated by the VR1 antagonist, capsazepine (CPZ). Finally, we demonstrated that VR1 expression on distinct thymocytes was associated with the selective ability of CPS to trigger DNA fragmentation in VR1+ CD4+ and DN thymocytes. Overall, our results suggest that the expression of VR1 on thymocytes may function as a sensor of harmful stimuli present in the thymic environment.

Video laparoscopic surgery: is out-of-hospital thromboprophylaxis necessary?

Despite widespread use of laparoscopic procedures, no adequate data are available to support specific recommendations for venous thromboprophylaxis in patients undergoing laparoscopic surgery. This prospective, randomized trial is the first to be designed to evaluate a regimen of out-of-hospital thromboprophylaxis after laparoscopic surgery. Consecutive patients admitted for laparoscopic surgery were considered for the study. The thromboprophylaxis regimen used for each patient was based on a risk score. Possible thromboprophylactic measures included elastic stockings and pre- and postoperative Dalteparin or early ambulation. At discharge, patients were randomly allocated either to continue Dalteparin for 1 week, or to receive no further prophylaxis. Patients judged to be at low risk were not randomized. Compression ultrasound of the leg veins was performed in all patients 4 weeks after hospital discharge. Fifty-three patients, all with acute appendicitis, were judged to be at low risk of deep vein thrombosis and were not included in the randomized study. The remaining 209 patients fell into two groups: 104 patients received postdischarge Dalteparin and 105 patients did not. The incidence of deep vein thrombosis was 0% (0 of 104) vs. 0.95% (one of 105), respectively (P = 1.00). The risk of postdischarge venous thromboembolism is low in patients undergoing laparoscopic surgery who receive in-hospital thromboprophylaxis. Given this low risk, a clinical trial powered to determine if extending prophylaxis in such patients reduces the risk of clinically apparent deep vein thrombosis would be unfeasibly large.