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PubMed2000

In vivo and in vitro stability of modified poly(urethaneurea) blood sacs.

In the present study, we investigate the in vivo and in vitro stability of modified poly(urethaneurea) (BioSpan MS/0.4) blood sacs. Blood sacs were utilized primarily in left ventricular assist devices that were implanted in calves for times ranging from 5 to 160 days. Cyclic testing in vitro was also conducted on similar sacs. Various analytical methods were employed to characterize the sacs after in vivo or in vitro service and corresponding retained "control" sacs. These methods included ATR-FTIR spectroscopy, scanning electron microscopy and gel permeation chromatography. In general, the characteristics of implanted and in vitro cycled sacs were similar to their control sacs. Thermal and microtensile properties were unchanged after testing. The same was true for the ATR-FTIR spectra, indicating relative chemical stability for the time frames explored here. The only significant changes occurred in molecular weight and gross surface morphology. A modest increase in weight average molecular weight was observed for most implanted blood sacs, indicating some type of chain extension or branching reaction in vivo. Although the surface morphologies of implanted blood sacs were often similar to their control sacs, we sometimes observed limited pitting on the nonblood contacting surfaces in regions of the sac that experience maximum bending during service.

Animals↗

PubMed2003

Distribution of sac pressure in an experimental aneurysm model after endovascular repair: the effect of endoleak types I and II.

PURPOSE: To study in an experimental aneurysm model the differential distribution of strain/pressure (S/P) on the aneurysm wall before and after endograft exclusion and in the presence of individual type I and type II endoleaks. METHODS: Two tapered elliptical Gore-Tex patches were sutured to an anterior and posterior longitudinal arteriotomy of an 8-mm Gore-Tex tube graft, thus creating a fusiform aneurysm. Two S/P transducers were placed at the proximal sac adjacent to the proximal neck, 2 at the site of the widest sac diameter, and 2 at the sac adjacent to the distal neck. The aneurysm, which was connected to a pulsatile pump system, was excluded using a 10-mm endograft. Type I and type II endoleaks were created and tested individually. S/P measurements were obtained at systemic systolic pressures (BP) of 80, 110, and 150 mmHg. Thrombosis of the sac contents was induced by injection of thrombin and calcium in the sac. Angiography was used to verify presence or absence of flow in the sac. RESULTS: Aneurysm exclusion resulted in significant S/P reductions at all 3 BP levels versus prior to exclusion (p<0.05). Thrombus in the sac did not alter S/P in the excluded sac (p>0.05 for all 3 BP levels). In the presence of a proximal type I endoleak, S/P distribution was not uniform, and S/P at the proximal neck was close to S/P prior to exclusion (p>0.05 no graft versus type I endoleak for all 3 BP levels). This was also true in the presence of thrombus. With a type II endoleak, S/P was more evenly distributed and was not significantly elevated compared to the pressure without an endoleak (p>0.05, graft versus type II endoleak for all 3 BP levels). Thrombus had no effect on intrasac S/P with a type II endoleak. Intrasac S/P was significantly higher in the presence of a type I endoleak compared to a type II endoleak when BP=150 mmHg (p=0.008). CONCLUSIONS: Endovascular exclusion of an aneurysm results in uniform S/P reduction in the aneurysm sac. Type I endoleak, but not type II endoleak, results in significantly higher S/P in an area of the sac adjacent to the proximal neck. Thrombus does not result in significantly different S/P distribution in the aneurysm sac.

Angioplasty↗

PubMed2001

Yolk-sac hematopoiesis: the first blood cells of mouse and man.

OBJECTIVE: To review the process of blood-cell formation in the murine and human yolk sac. DATA SOURCES: Most articles were selected from the PubMed database. DATA SYNTHESIS: The yolk sac is the first site of blood-cell production during murine and human ontogeny. Primitive erythroid cells originate in the yolk sac and complete their maturation, including enucleation, in the bloodstream. Though species differences exist, the pattern of hematopoietic progenitor cell emergence in the yolk sac is similar in mouse and man. In both species, there is a stage of development where both primitive red blood cells and definitive erythroid progenitors are produced in the yolk sac. An "embryonic" hematopoietic stem cell that engrafts in myeloablated newborn but not adult mice can be detected in the murine yolk sac and embryo. Stem-cell activity in the human yolk sac has not been reported. CONCLUSIONS: The yolk sac is the sole site of embryonic erythropoiesis. However, definitive erythroid, myeloid, and multipotential progenitors also originate in the yolk sac. The relationship between these progenitors and the "embryonic" hematopoietic stem cell has not been elucidated. Yolk sac-derived progenitor cells may seed the developing liver via the circulation and serve as the immediate source of the mature blood cells that are required to meet the metabolic needs of the rapidly growing fetus.

Animals↗

PubMed2002

Embryonic macrophages of early rat yolk sac: Immunohistochemistry and ultrastructure with reference to endodermal cell layer.

Macrophages are multifunctional cells that participate in numerous biological processes; they actively phagocytose foreign particles and cell debris. Embryonic tissue macrophages are present at early stages of mammalian development; their ontogeny and function is still under investigation. Our study used immunohistochemistry and electron microscopy to investigate early rat yolk sac macrophages using mouse antirat macrophage monoclonal antibodies (mAb) Mar 1 and Mar 3 produced by our laboratory. Mar 3 mAb revealed the first emergence of immature macrophages in the rat yolk sac at fetal day nine coinciding with the beginning of yolk sac haemopoiesis that consisted mainly of erythropoiesis, while Mar 1 mAb detected specifically rat yolk sac macrophages at about the 13th to 14th day of gestation. Immunoreactivity against Mar mAbs was mainly located in the yolk sac endodermal cell layer, which may signify endodermal origin of the yolk sac macrophages. Ultrastructurally mature yolk sac macrophages contained numerous endocytic vesicles or vacuoles, well-developed Golgi saccules and many electron dense granules in their cytoplasm and a number of microvillous projections from the cell surface. After establishment of the circulation between yolk sac and embryo, Mar 3 positive cells were also demonstrated inside fetal undifferentiated mesenchymal tissue at fetal day 12. The study demonstrated the first emergence of immature yolk sac macrophages being among the earliest haemopoietic cells formed in mammalian development. Thus, Mar mAbs managed to detect macrophage differentiation antigens through their development early in the rat yolk sac.

Animals↗

PubMed1997

In vivo repopulating hematopoietic stem cells are present in the murine yolk sac at day 9.0 postcoitus.

The murine yolk sac, being the first site of embryonic blood cell production, has long been theorized to contain the migrating hematopoietic stem cells (HSC) that seed the liver and initiate hematopoiesis on day 10.0 postcoitus (pc). However, it remains controversial whether yolk sac cells isolated before day 11.0 pc possess any long-term repopulating HSC activity upon transplantation into adult recipient mice. We hypothesized that failure to demonstrate engraftment of day <11.0 yolk sac cells in adult hosts may result from an inability of yolk sac cells to home to the active adult hematopoietic sites (spleen and bone marrow). In the present studies, we transplanted yolk sac cells into conditioned newborn mice in whom the liver, as well as the spleen and bone marrow, concomitantly function as a site of blood cell formation. We report that yolk sac cells isolated from day 9.0 pc embryos provide long-term multilineage reconstitution for at least 11 months in primary conditioned newborn mice and for at least 6 months in secondary recipients. Donor yolk sac HSC progeny repopulated mature peripheral blood, thymus, spleen, and bone marrow lymphoid, myeloid, and erythroid compartments. Thus, day 9.0 pc yolk sac HSC can contribute to definitive multilineage hematopoiesis in transplanted recipients. Determination of HSC activity in the day 9.0 pc murine yolk sac suggests that yolk sac HSC are available to seed the liver on day 10.0 pc when definitive hematopoiesis is initiated.

Animals↗

PubMed2002

Hearing preservation surgery for small endolymphatic sac tumors in patients with von Hippel-Lindau syndrome.

OBJECTIVE: To determine the incidence of bilateral endolymphatic sac tumors in von Hippel-Lindau syndrome and to describe the technique and results of hearing preservation surgery for small endolymphatic sac tumors in a series of patients with von Hippel-Lindau syndrome. STUDY DESIGN: Analysis of the literature to determine the incidence of bilateral endolymphatic sac tumors and a retrospective case review of hearing preservation surgery for removal of small endolymphatic sac tumors in four patients with von Hippel-Lindau syndrome. SETTING: Tertiary care academic medical centers. PATIENTS: Four patients with von Hippel-Lindau syndrome (three with bilateral endolymphatic sac tumors) and progressive sensorineural hearing loss in which preoperative imaging studies revealed in situ or small endolymphatic sac tumors without ipsilateral labyrinthine destruction. INTERVENTION: All four patients had complete surgical excisions of the endolymphatic sac tumor via one of three surgical approaches with the goal of hearing preservation. One patient had bilateral surgery. MAIN OUTCOME MEASURES: Audiometric and radiographic. RESULTS: Nearly one-third (30.2%) of patients with von Hippel-Lindau syndrome and endolymphatic sac tumors have bilateral disease. All four patients (five ears) maintained serviceable hearing postoperatively after surgical excision of the endolymphatic sac tumor via a variety of approach options. CONCLUSION: The discovery of a small or in situ endolymphatic sac tumor affords the patient the option of surgical removal with hearing preservation. This is critical in the patient with von Hippel-Lindau syndrome who is at risk for bilateral disease and complete bilateral anacusis if tumor growth progresses.

Adult↗

PubMed1995

The endolymphatic sac: microsurgical topographic anatomy.

The endolymphatic sac is part of the membranous labyrinth; it plays an important role in the hearing mechanism. Injury to the endolymphatic sac may, over time, severely compromise hearing. The endolymphatic sac is located in a duplication of the dura of the posterior aspect of the petrous pyramid and is, therefore, in the surgical field of many neurosurgical operations performed on the posterolateral cranial base. The endolymphatic sac was exposed bilaterally in 10 anatomic specimens; the distance from the center of the sac to the posterior lip of the internal auditory meatus and to the XIth nerve in the jugular foramen was measured with a caliper. Also measured was the distance between the center of the sac and the closest point on the petrous ridge and the distance between that point and the petro-sigmoid intersection. The petro-sigmoid intersection was defined as the point at which the medial aspect of the sigmoid sinus intersects the lateral aspect of the petrous ridge. The dimensions of the sac were also recorded. On the average, the sac was found to be 15.7 mm posterosuperior (superolateral) to the XIth nerve in the jugular foramen (range, 11.0-18.5 mm) and 13.3 mm posterior (lateral) to the internal auditory meatus (range, 10.0-18.0 mm). The center of the sac was 24.1 mm (mean value) (range, 20.0-28.0 mm) in front of the petro-sigmoid intersection at a point 11.5 mm (mean value) (range, 8-17 mm) below the petrous ridge. The mean width and height of the sac were 3.83 (range, 2-6 mm) and 3.80 mm (range, 2.5-8 mm), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Anatomy, Artistic↗

PubMed1991

In vitro development of murine T cells from prethymic and preliver embryonic yolk sac hematopoietic stem cells.

Mature T cells are derived from prethymic stem cells, which arise at one or more extrathymic sites and enter and differentiate in the thymus. The nature of these prethymic stem cells is a critical factor for the formation of the T-cell repertoire. Although the bone marrow of adult mice can provide such stem cells, their origin during murine embryogenesis is still undetermined. Among potential sites for these progenitor cells are the fetal liver and the embryonic yolk sac. Our studies focus on the yolk sac, both because the yolk sac appears earlier than any other proposed site, and because the mammalian yolk sac is the first site of hematopoiesis. Although it has been shown that the yolk sac in midgestation contains stem cells that can enter the thymic rudiment and differentiate toward T-cell lineage, our aim was to analyze the developmental potential of cells in the yolk sac from earlier stages, prior to the formation of the liver and any other internal organ. We show here that the yolk sac from 8- and 9-day embryos (2-9 and 13-19 somites, respectively) can reconstitute alymphoid congenic fetal thymuses and acquire mature T-cell-specific characteristics. Specifically, thymocytes derived from the early embryonic yolk sac can progress to the expression of mature T lymphocyte markers including CD3/T-cell receptor (TCR), CD4 and CD8. In contrast, we have been unable to document the presence of stem cells within the embryo itself at these early stages. These results support the hypothesis that the stem cells capable of populating the thymic rudiment originate in the yolk sac, and that their presence as early as at the 2- to 9-somite stage may indicate that prethymic stem cells found elsewhere in the embryo at later times may have been derived by migration from this extra-embryonic site. Our experimental design does not exclude the possibility of multiple origins of prethymic stem cells of which the yolk sac may provide the first wave of stem cells in addition to other later waves of cells.

Animals↗

PubMed1987

Distinguishing normal from abnormal gestational sac growth in early pregnancy.

In order to evaluate normal and abnormal gestational sac development, serial sonograms were performed in 83 women whose initial sonogram demonstrated a gestational sac lacking a detectable embryo. Of 53 normal gestations, the mean sac growth was 1.13 mm/day (range, 0.71-1.75). In comparison, of 30 abnormal gestations, 24 demonstrated sac growth, and of these, the mean growth was 0.70 mm/day (range, 0.14-1.71). Based on these observations, we suggest that gestational sac growth of less than or equal to 0.6 mm/day is evidence for abnormal development. Analysis of the initial and follow-up scans for the 53 normal gestations showed that a living embryo was always detected when the mean gestational sac was greater than 25 mm in average diameter, and a yolk sac was always seen when the mean sac diameter was greater than 20 mm. In comparison, of 30 abnormal gestations, six were greater than 25 mm without a detectable embryo, and four were greater than 20 mm without a yolk sac. Recommendations for the optimal time of a follow-up sonogram are presented based on the initial sac size.

Embryo Loss↗

PubMed1988

Value of the yolk sac in evaluating early pregnancies.

To determine the potential value in identifying a yolk sac in women with suspected ectopic pregnancies, 211 consecutive women who were referred to pelvic sonography with this clinical indication were prospectively studied. Of the 211 patients examined, 104 proved to have a normal intrauterine pregnancy (IUP), 59 had an abnormal (nonviable) IUP, and 48 had a surgically-proven ectopic pregnancy. Considering only intrauterine "sacs" that lacked a visible embryo, a yolk sack was identified in 16 of 26 (62%) normal IUPs, and 3 of 19 (16%) abnormal IUPs, but was not seen in any of six pseudo-gestational sacs in women with ectopic pregnancies. In comparison, a double decidual sac (DDS) finding was thought to be present in 24 of 26 (92%) normal gestational sacs, 12 of 19 (63%) abnormal gestational sacs, and 2 of 6 (33%) pseudogestational sacs. We conclude that in women in whom a living embryo is not identified, demonstration of a yolk sac is reliable evidence for early IUP, and virtually excludes the possibility of an ectopic gestation. Although a yolk sac is less frequently observed than a DDS finding, it is also more specific evidence for an IUP. Careful attention to the yolk sac should permit earlier, more reliable diagnoses of IUP than previously possible.

Female↗

PubMed1999

An anatomical study of the respiratory air sacs in ostriches.

An accurate description of the number, location and relative position of the air sacs and their diverticula in the ostrich is essential for a better understanding of the pathogenesis of air sacculitis in this bird. The air sacs were studied in ten ostriches of varying ages by latex or silicone casting of the respiratory tract and dissection. Results revealed that the air sacs of the ostrich conform to the general pattern in birds. Cervical, lateral and medial clavicular, cranial and caudal thoracic, and abdominal air sacs are present. The left and right medial clavicular air sacs fuse with each other ventrally to the trachea to form a single, median compartment. A unique, large gastric diverticulum which covers the caudal aspects of the proventriculus and gizzard originates from the median compartment of the clavicular air sac. The lateral clavicular air sacs and their diverticula are similar to those of other bird species, with the exception that humeral diverticula are absent. Both abdominal air sacs are relatively small, with the left sac being the larger. Perirenal and femoral diverticula, similar to those found in other bird species, are present. However, the entire femur is aerated by the femoral diverticulum which also forms a large, subcutaneous division caudally and caudo-laterally to the femur. The presence of this subcutaneous part has practical implications for injury and intramuscular injections. The number and location of ostia connecting the air sacs to the bronchial tree are generally similar to those reported in other bird species.

Air Sacs↗

PubMed1994

Murine yolk sac endoderm- and mesoderm-derived cell lines support in vitro growth and differentiation of hematopoietic cells.

The mechanisms involved in the induction of yolk sac mesoderm into blood islands and the role of visceral endoderm and mesoderm cells in regulating the restricted differentiation and proliferation of hematopoietic cells in the yolk sac remain largely unexplored. To better define the role of murine yolk sac microenvironment cells in supporting hematopoiesis, we established cell lines from day-9.5 gestation murine yolk sac visceral endoderm and mesoderm layers using a recombinant retrovirus vector containing Simian virus 40 large T-antigen cDNA. Obtained immortalized cell lines expressed morphologic and biosynthetic features characteristic of endoderm and mesoderm cells from freshly isolated yolk sacs. Similar to the differentiation of blood island hematopoietic cells in situ, differentiation of hematopoietic progenitor cells in vitro into neutrophils was restricted and macrophage production increased when bone marrow (BM) progenitor cells were cultured in direct contact with immortalized yolk sac cell lines as compared with culture on adult BM stromal cell lines. Yolk sac-derived cell lines also significantly stimulated the proliferation of hematopoietic progenitor cells compared with the adult BM stromal cell lines. Thus, yolk sac endoderm- and mesoderm-derived cells, expressing many features of normal yolk sac cells, alter the growth and differentiation of hematopoietic progenitor cells. These cells will prove useful in examining the cellular interactions between yolk sac endoderm and mesoderm involved in early hematopoietic stem cell proliferation and differentiation.

Animals↗

PubMed1997

Erythropoietin-receptor expression and function during the initiation of murine yolk sac erythropoiesis.

Although erythropoietin is necessary for definitive (fetal liver and bone marrow) erythropoiesis, the role of erythropoietin signaling in primitive (yolk sac) hematopoiesis has not been well defined. In situ hybridization studies have revealed that erythropoietin-receptor (EPOR) mRNA accumulation begins in mesoderm cell masses of the developing yolk sac of the neural plate stage embryo (E7.5) before the development of morphologically recognizable erythroblasts. EPOR mRNA is also present in yolk sac blood islands at early somite stages (E8.5). These findings suggest that EPOR functions during early stages of yolk sac erythropoiesis. We have used a serum-free murine yolk sac explant system (Palis et al., Blood 86:156, 1995) to investigate the initial differentiation of primitive erythroblasts from extraembryonic mesoderm cells. Exogenous erythropoietin increased both erythroblast numbers and betaH1-globin accumulation in yolk sac explants, suggesting that primary yolk sac erythroblasts are directly responsive to erythropoietin. An antisense oligodeoxynucleotide (ODN) experimental approach was used to examine the functional role of erythropoietin signaling during the initiation of yolk sac hematopoiesis in yolk sac explants. Antisense EPOR ODN produced a >50% reduction (p < 0.005) in the number of differentiating primitive erythroblasts, >95% reduction in betaH1-globin accumulation (p < 0.001), and a >50% reduction (p < 0.01) in the number of CFU-E and BFU-E compared with missense EPOR ODN-treated and untreated control explants. Antisense EPOR ODN also blocked the increase in primitive erythroblast number induced by exogenous erythropoietin. We conclude that erythropoietin/EPOR signaling is functionally active during the initial proliferation and differentiation of primary yolk sac erythroblasts. These results also suggest that other growth factor signaling cascades are active during the onset of mammalian erythropoiesis.

Animals↗

PubMed2003

A constricting ring structure within the wall of the inguinal hernia sac in infants and children and its role in the occurrence of incarceration.

The study aims to demonstrate the presence of a fibrous or fibromuscular ring structure within the wall of the sacs of inguinal hernia in children and its importance in the development of incarceration as a direct cause of this complication. A case series study of 784 children with unilateral inguinal hernias operated on over a period of 9 years (1992-2000) in two teaching hospitals (Mosul, Iraq). All underwent herniotomy. The sacs were examined for the presence of a ring structure, and the excised sacs containing the rings were studied histopathologically. The presence of the hernia sac ring (HSR) and its significance in the causation of incarceration was studied. Out of 784 cases, 660 were elective and 124 incarcerated hernias. In 56 sacs the hernia sac ring (HSR) was present - 36 rings in the elective and 20 rings in the sacs of incarcerated hernias. The histopathology of the hernia sac ring was fibrous or fibromuscular tissue. This ring has its significance in the development of incarceration. Hernias with the HSR are three times more liable to incarceration than those without the ring. Incarcerations of inguinal hernia in children are usually caused by the inguinal rings. Another cause for incarceration being studied is a fibrous or fibromuscular ring structure identified within the wall of the hernial sac, causing the incarceration in 5.6% of elective (nonincarcerated) hernias and 16% of incarcerated hernia patients. Patients with these hernia sac rings are three times more liable to incarceration than others.

Child↗

PubMed1980

Incomplete gas mixing in air sacs of the duck.

During normal breathing, the CO2 concentration in caudal air sacs of birds is higher, and the O2 concentration lower, than expected on the basis of the known air flow pattern. We have experimentally tested two hypotheses which could explain this finding: (1) Preferential shunting of re-inspired dead space gas into caudal air sacs; (2) Incomplete mixing of inspired and residential air sac gas. - Different portions of the inspired air in anesthetized ducks were labeled by injecting a small bolus of argon (Ar) into the trachea. The resulting Ar concentration was recorded continuously in the caudal thoracic air sac at the ostium and in deeper regions.-The amount of Ar entering the sac was found to be independent of the volume inspired prior to injection of the label, and hypothesis (1) thus dismissed. However, during inspiration and subsequent expiration the Ar bolus was found to be neither perfectly mixed within the inspired gas nor with the air sac residential gas. More than 10 sec of breath-hold were necessary for air sac gas to approach an equilibrium value. Gas layering (stratification) in caudal air sacs gas is proposed to cause the high CO2 and low O2 levels during steady state breathing, as air sac residential gas equilibrates with a layer of dead space gas that enters the air sac on each breath and contains a higher CO2 and lower O2 concentration than the mixed inspirate.

Animals↗

PubMed2004

Aneurysmal hypertension and its relationship to sac thrombus: a semi-qualitative analysis by experimental fluid mechanics.

OBJECTIVES: To ascertain the effect of aneurysm thrombus and luminal diameter on arterial blood pressure within the abdominal aortic aneurysm lumen and at the sac wall. METHODS: A life-like abdominal aortic aneurysm was incorporated in a pulsatile flow unit, using systemic blood pressure settings of 140/100 mmHg and 130/90 mmHg (denoted the high and low settings, respectively). Aneurysm sac pressure was measured in the absence of thrombus within the sac. This was repeated after a thrombus analogue (gelatine) was introduced into the aneurysm model in an asymmetric fashion. Luminal and sac wall pressures were compared to the systemic pressure, and to each other, in both blood pressure settings. Statistical analysis was performed using ANOVA in Minitab 13. RESULTS: In the empty sac, the luminal and sac wall pressures were identical to the systemic pressures at the high and low settings. After introduction of thrombus, pressure was transmitted in a monophasic pulsatile fashion, measuring 166/142/151 mmHg (SP/DP/MP) at the sac wall, while the corresponding intraluminal pressure was 164/136/145 mmHg (p<0.001, high setting). By contrast, in the low setting, these readings were 157/133/141 (sac wall) and 160/128/138 mmHg (lumen; p<0.001). The sac wall pressures were significantly higher than the luminal pressures for both high and low settings (p<0.001). CONCLUSIONS: Thrombus has a significant effect on the intraaneurysmal lumen itself and causes localised hypertension with high intraluminal pressures. The differences between the sac wall/luminal pressures may affect regional aneurysm wall biomechanics, but needs further study.

Aortic Aneurysm, Abdominal↗

PubMed2006

Sac behavior after aneurysm treatment with the Gore Excluder low-permeability aortic endoprosthesis: 12-month comparison to the original Excluder device.

BACKGROUND: The original Gore Excluder endoprosthesis (OGE) used both during and briefly after clinical trials was associated with less sac regression and more sac growth than some other devices, even without apparent endoleaks, presumably because of transmural movement of serous fluid across the expanded polytetrafluoroethylene material. In July 2004, the device was modified to decrease graft permeability. This study evaluated the efficacy of the new Excluder Low-Permeability Device (ELPD) at 1 year and compared it with the OGE and the Cook Zenith device (ZEN). METHODS: From Food and Drug Administration approval of the Excluder in November 2002 until June 2005, 283 patients underwent endovascular repair of abdominal aortic aneurysms with the Gore Excluder or the ZEN. Postoperative surveillance included computed tomographic scans at 1 and 12 months; 181 (64%) patients completed both scans. The 1-month computed tomographic scan served as a baseline, and the minor axis diameter, measured at the largest axial cut of the abdominal aortic aneurysm, was compared with the same measurement at 1 year. A sac size change of 5 mm or more was considered significant. Sixty patients treated with the OGE were compared with 72 patients treated with the ELPD. Forty-nine patients treated during the same time period with the ZEN, known for early sac shrinkage, were used as a reference. All measurements were performed by one observer from a digital workstation. Wilcoxon signed rank tests (pairwise) or Kruskal-Wallis tests (three groups) were used for intergroup comparison of continuous variables, whereas chi2 statistics or Fisher exact tests were used to compare categorical variables. RESULTS: Patient age and sex and mean maximum aneurysm diameter at baseline were similar among groups (P = .59, .27, and .46, respectively). Graft migration, stent fractures, acute surgical conversion, late abdominal aortic aneurysm rupture, or aneurysm-related deaths were not observed. Type II endoleak rates were similar between ELPD and ZEN (23.6% and 20.4%; P = .68). Although a higher rate of endoleaks was seen with OGE (36.7%), this was not significant when compared with the other two devices (P = .11). At 1 year, patients treated with ELPD had a sac regression rate that was significantly higher than that for patients treated with OGE (63.9% vs 25%; P < 0.001) and was similar to that for patients treated with ZEN (65.3%). Significant sac expansion was not observed with ELPD. CONCLUSIONS: At 1 year, similar to ZEN, significant aneurysm sac regression and minimal sac expansion were noted after endovascular repair of abdominal aortic aneurysms with ELPD. Low-porosity fabric used in the construction of endoprostheses seems to be an important factor in early aneurysm sac shrinkage. Long-term efficacy regarding the prevention of sac enlargement remains unclear, and further follow-up is suggested.

Aged↗

PubMed1998

The pathological evaluation of the pediatric inguinal hernia sac.

BACKGROUND: The College of American Pathologists has suggested that institutions should establish guidelines for the evaluation of the hernia sac. In addition, some states require the submission of this tissue for pathological evaluation. Yet, neither evidence-based guidelines nor published reviews for the evaluation of the pediatric hernia sac are available. Therefore, this retrospective study was conducted to document experience with the evaluation of the pediatric hernia sac. METHODS: All reports of the evaluation of hernia sacs submitted to the Department of Pathology during an 8-year period were reviewed. The case of any report that differed in any way from "consistent with hernia sac" was evaluated for the effect of the findings on the clinical course. RESULTS: A total of 7,924 hernia sacs were submitted on 6,034 patients. Microscopic evaluation was performed on 534. A total of 7,567 (95.4%) submitted specimens on 5,743 patients were "consistent with hernia sac" and demonstrated no other findings. Three hundred fifty-seven specimens contained findings in addition to hernia sac. In no patient did the results of the evaluation have an effect on the patient care. CONCLUSIONS: There is strong evidence that the routine pathological evaluation of pediatric hernia sacs offers little relevant clinical information. Mandatory tissue submission of hernia sacs should be reconsidered.

Child↗