Phase Ib Safety, Two-Dose Study of MultiGeneAngio in Patients with Chronic Critical Limb Ischemia.

Critical limb ischemia (CLI) is the most severe presentation of peripheral arterial disease. We developed cell-based therapy entailing intra-arterial injection of autologous venous endothelial cells (ECs) modified to express angiopoietin 1, combined with autologous venous smooth muscle cells (SMCs) modified to express vascular endothelial growth factor. This combination promoted arteriogenesis in animal models and was safe in patients with limiting claudication. In an open-label, phase Ib study, we assessed the safety and efficacy of this therapy in CLI patients who failed or were unsuitable for surgery or intravascular intervention. Of 23 patients enrolled, 18 with rest pain or non-healing ulcers (Rutherford categories 4 and 5) were treated according to protocol, and 5 with significant tissue loss (Rutherford 6) were treated under compassionate treatment. Patients were assigned randomly to receive 1 × 107 or 5 × 107 (EC-to-SMC ratio, 1:1) of the cell combination. One-year amputation-free survival rate was 72% (13/18) for Rutherford 4 and 5 patients; all 5 patients with Rutherford 6 underwent amputation. Of the 12 with unhealing ulcers at dosing, 6 had complete healing and 2 others had >66% reduction in ulcer size. Outcomes did not differ between the dose groups. No severe adverse events were observed related to the therapy.

Implementation of an institutional protocol to improve inferior vena cava utilization and outcomes.

To evaluate the impact of an institutional protocol on patterns of use and outcomes of inferior vena cava filters (IVCF). Following a multidisciplinary effort, an institutional protocol involving dedicated follow-up of patients receiving IVCF and a physician education program regarding IVCF utilization, was established. We prospectively collected data of patients who received IVCF during 2015-2016, following protocol implementation (POST group). For comparison, we reviewed records of patients who received IVCF during 2009-2014, before implementation of the institutional protocol (PRE group). In the PRE and POST groups, 76 and 38 IVCF per year were inserted respectively, with an overall decrease of 50%. IVCF were more likely to be placed for therapeutic rather than prophylactic indications in the POST compared to the PRE group (P = 0.003). Follow-up rates at our coagulation clinic were significantly higher in the POST than the PRE group (100 vs. 22.9%, P < 0.0001), as were rates of attempted retrieval: 60.5% (23/38) vs. 16.7% (76/455), P < 0.0001. Failed retrieval occurred at similar rates: 15.8% (12/76) vs. 18.2% (4/22), P = 0.75. There was a trend towards a lower thrombotic complication rate in the POST than the PRE group: 2.6 vs. 11.2%, P = 0.16. Implementation of an institutional protocol significantly decreased the use of IVCF and increased the retrieval rate. Such intervention could potentially lead to lower rates of IVCF-related complications in the future.

Patterns of use and outcome of inferior vena cava filters in a tertiary care setting.

BACKGROUND: Inferior vena cava (IVC) filter placement is increasing although the evidence to justify their use is limited. Many filters are left in place indefinitely, thereby exposing patients to long-term complications. OBJECTIVES: To review indications, complications, and follow-up data of patients undergoing IVC filter placement at our center. METHODS: A retrospective review of consecutive admitted patients who underwent IVC filter insertion in a large university hospital with a level I trauma center. Thrombosis specialists retrospectively assessed the appropriateness of indication for IVC filter placement as well as referral for retrieval. RESULTS: Overall, 405 filters were inserted between 2009 and 2013. All filters were retrievable. IVC filter was placed as a primary prevention in 42% of patients. Fifty-two patients (12.8%) experienced at least one filter-related complication. The most common complication was deep vein thrombosis occurring in 6.9% of cases. Almost a third of all complications occurred in filters originally placed for prophylactic indications. Only 13.6% of filters were successfully removed. Nevertheless, according to our reviewers, an attempt for filter retrieval should have been made in 57% of all cases and in 86% of trauma patients. A significantly higher retrieval rate was found in patients followed at our thrombosis clinic (P < 0.01). During follow-up, 95 patients (23.4%) died, most of them with active cancer. CONCLUSIONS: IVC filters are placed in many cases for prophylactic indications. Their low retrieval rates together with relatively high risk of long-term complications, questions their extensive utilization. Prospective trials addressing the safety and efficacy of IVC filters are still warranted.

Pharmacomechanical catheter-directed thrombolysis for pregnancy-related iliofemoral deep vein thrombosis.

PURPOSE: Pharmacomechanical catheter-directed thrombolysis (PCDT) is relatively contraindicated during pregnancy and postpartum. The purpose of this study was to evaluate outcomes of PCDT in this population. MATERIALS AND METHODS: Data for 11 consecutive patients (aged 21-35 y) undergoing PCDT at a tertiary center for symptomatic pregnancy-related iliofemoral deep vein thrombosis (DVT) were retrospectively reviewed. Details regarding patient presentation, location and extent of thrombus, the PCDT procedure, outcomes, frequency of postthrombotic syndrome (PTS), and subsequent pregnancies were recorded. Two patients who presented in the first trimester terminated their pregnancies after PCDT, 2 patients who presented in the third trimester delayed PCDT until after delivery, and 7 patients who presented with postpartum DVT underwent immediate PCDT. RESULTS: Thrombus extended into the inferior vena cava in 5 patients (45%) and into popliteal/tibial veins in 7 (64%). Four patients (36%) had synchronous pulmonary embolism and three had May-Thurner compression. Median interval from diagnosis to PCDT was 5 days (range, 2-68 d); median duration of urokinase infusion was 27 hours (range, 16-72 h). Greater than 90% clot lysis was achieved in 9 of 11 patients (82%). Metal stents were placed in 8 of 11 patients (73%). A self-limiting popliteal hematoma developed in 1 patient, and 2 had early recurrent thrombosis requiring repeat PCDT. At median 20-month follow-up, nonocclusive thrombus was seen in 5 patients. No patient developed PTS. Three patients, all with stents, had uneventful pregnancies after PCDT. CONCLUSIONS: Pharmacomechanical catheter-directed thrombolysis achieved encouraging initial outcomes in this series. Validation in prospective trials with larger enrollment and longer follow-up is needed.

Inferior vena cava (IVC) filters in children: A 10-year single center experience.

BACKGROUND: Venous thromboembolism (VTE) is an increasingly recognized problem among children and adolescents. Although inferior vena cava (IVC) filter placement for pulmonary embolism prevention is well reported in adults, data regarding safety and efficacy in the pediatric age group are lacking. PROCEDURE: At a large university hospital with a level I trauma center, medical records of children and adolescents who underwent IVC filter insertion were reviewed. Appropriateness of referral for retrieval was assessed in each case. RESULTS: Fifty-nine children and adolescents (mean age 16 years) successfully underwent IVC filter insertion. All filters placed were retrievable. In 47 patients (79.7%), prophylactic filters were placed in the absence of acute VTE in the setting of trauma. In eight patients (13.5%), filters were placed due to contraindication to anticoagulation therapy with concomitant lower extremity deep vein thrombosis or pulmonary embolism. Filters were successfully retrieved in only 12 patients (20.3%), although an attempt at removal was appropriate and feasible in over 90% of cases. Mean duration of follow-up was 2.1 (range 0.4-7.3) years. A significantly higher retrieval rate was found in patients followed at our thrombosis clinic (P < 0.01). Ten patients (17%) experienced at least one filter-related complication. CONCLUSIONS: Although in most cases, IVC filters were placed for prophylactic indications, the evidence to support their role in this setting is limited. Their low retrieval rate and high filter-related complication rate question their extensive utilization in children. Dedicated follow-up is necessary to detect complications and to ensure that an attempt at retrieval is made when feasible.

Endovascular infection following inferior vena cava (IVC) filter insertion.

Inferior vena cava filter (IVC) placement is increasing significantly. However, due to low retrieval rates, many filters are left in place indefinitely thereby exposing patients to long-term filter-related complications. This study reports a series of three patients with IVC filter infection. Cases were identified during retrospective review of medical records of all patients undergoing an IVC filter insertion at a single tertiary care university hospital between 2009 and 2013. Clinical presentation, radiological features and management are discussed. Two patients presented within days of filter placement, while the other one presented 1 year later. In two patients, fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) was found to be a sensitive method to diagnose IVC filter infection. Endovascular infection of IVC filter is a rare event. In patients with IVC filter in place and fever of unknown origin or persistent bacteremia, this complication should be suspected. FDG PET/CT has a diagnostic value in this challenging diagnosis.

Trans-arterial chemo-embolization is safe and effective for elderly advanced hepatocellular carcinoma patients: results from an international database.

OBJECTIVE: Hepatocellular carcinoma (HCC) incidence among elderly patients is increasing. Trans-arterial chemo-embolization (TACE) prolongs survival in selected HCC patients. The safety and efficacy of TACE in elderly patients has not been extensively studied. The objective of this study was to assess the safety and efficacy of TACE in elderly patients (older than 75) with HCC. DESIGN: Combined HCC registries (Spain, Italy, China and Israel) and cohort design analysis of patients who underwent TACE for HCC. RESULTS: Five hundred and forty-eight patients diagnosed and treated between 1988 and 2010 were included in the analysis (China 197, Italy 155, Israel 102 and Spain 94,). There were 120 patients (22%) older than 75 years and 47 patients (8.6%) older than 80. Median (95% CI) survival estimates were 23 (17-28), 21 (17-26) and 19 (15-23) months (P=0.14) among patients aged younger than 65, 65-75 and older than 75 respectively. An age above 75 years at diagnosis was not associated with worse prognosis, hazard ratio of 1.05 (95% CI 0.75-1.5), controlling for disease stage, sex, diagnosis year, HBV status and stratifying per database. No differences in complication rates were found between the age groups. CONCLUSIONS: TACE is safe for patients older than 75 years. Results were similar over different eras and geographical locations. Though selection bias is inherent, the results suggest overall adequate selection of patients, given the similar outcomes among the different age groups.

Image-guided sharp recanalization of a benign J pouch anastomotic occlusion facilitates surgical repair.

A 27-year-old man with a 9-year history of ulcerative colitis who had undergone total proctocolectomy with construction of a continent pouch in 2008 presented 1 year later with occlusion of the ileal pouch-anal anastomosis precluding ileostomy closure. An attempt at surgical reconstruction at an outside hospital failed, and the patient was informed that he would have a permanent stoma. A further attempt at blind surgical recanalization of the occlusion risked sphincter damage and was deferred. In 2010, reconstruction was performed using a hybrid approach combining image-guided sharp recanalization of the occluded anastomosis with positioning of a large-diameter Foley balloon catheter across the recanalized segment, followed by immediate surgical revision of the J pouch. Ileostomy closure was performed 1 month later. Continence was preserved. Surgical repair preceded by sharp recanalization with positioning of a balloon catheter across the occluding membrane may safely regain durable patency in a chronically occluded ileal pouch-anal anastomosis.

Patient radiation exposure during percutaneous endovascular revascularization of the lower extremity.

BACKGROUND: Percutaneous endovascular revascularization is emerging as the first line treatment for peripheral artery disease for both intermittent claudication and chronic critical limb ischemia. Radiation doses for these interventions have not been well documented. METHODS: A single center retrospective study of therapeutic endovascular lower extremity interventions performed between September 2006 and December 2011 was undertaken. Collected data included patient demographics, procedure indication, procedural access, anatomic location of occlusive disease (pelvis, thigh, below-knee, or multilevel), and radiation exposure parameters including dose area product (DAP) and fluoroscopy time. RESULTS: Data was available for 382 procedures performed in 313 patients. Eighteen procedures bilateral procedures were excluded. Access site and complete anatomic data were available for 346 procedures. DAP was significantly higher for procedures performed in the pelvis compared with thigh procedures (179.6 vs 63.2 Gy*cm(2); P < .0001) and below-knee procedures (179.6 vs 28.9 Gy*cm(2); P < .0001), despite shorter fluoroscopy times (11.8 vs 16.4 minutes; P < .0001 and 11.1 vs 31.06 minutes; P < .0001, respectively). Procedure access-site affected radiation dose as well; contralateral up-and-over access resulted in a higher DAP than antegrade access (112.2 vs 42.6 Gy*cm(2); P < .0001). In a multivariable analysis, anatomic location of the procedure showed the strongest association with radiation dose (P < .0001). CONCLUSIONS: Percutaneous endovascular revascularization for lower extremity peripheral artery disease involves a substantial radiation dose, comparable, on average, to a computed tomography scan of the abdomen and pelvis. Procedures performed in the pelvis for intermittent claudication involve more radiation than thigh or below-knee procedures for chronic critical limb ischemia. Radiation dose should be considered when planning these procedures.

Endovascular management of blunt renal artery trauma.

BACKGROUND: Renal artery injuries are rarely encountered in victims of blunt trauma. However, the rate of early diagnosis of such injuries is increasing due to increased awareness and the liberal use of contrast-enhanced CT. Sporadic case reports have shown the feasibility of endovascular management of blunt renal artery injury. However, no prospective trials or long-term follow-up studies have been reported. OBJECTIVES: To present our experience with endovascular management of blunt renal artery injury, and review the literature. METHODS: We conducted a retrospective study of 18 months at a level 1 trauma center. Search of our electronic database and trauma registry identified three patients with renal artery injury from blunt trauma who were successfully treated endovascularly. Data recorded included the mechanism of injury, time from injury and admission to revascularization, type of endovascular therapy, clinical and imaging outcome, and complications. RESULTS: Mean time from injury to endovascular revascularization was 193 minutes and mean time from admission to revascularization 154 minutes. Stent-assisted angioplasty was used in two cases, while angioplasty alone was performed in a 4 year old boy. A good immediate angiographic result was achieved in all patients. At a mean follow-up of 13 months the treated renal artery was patent in all patients on duplex ultrasound. The mean percentage renal perfusion of the treated kidney at last follow-up was 36% on DTPA renal scan. No early or late complications were encountered. CONCLUSIONS: Endovascular management for blunt renal artery dissection is safe and feasible if an early diagnosis is made. This approach may be expected to replace surgical revascularization in most cases.

Engineering In Situ Weldable Vascular Devices.

(1) Background: The minimally invasive implantation of medical devices is largely limited by their insertion profile, and, therefore, minimizing them constitutes a leading trend in the field. (2) Methods: This study introduces the in situ welding strategy, whereby the components of the stent grafts used to treat abdominal aortic aneurysms were decoupled, deployed sequentially, and welded together at the aneurysmal site, greatly reducing their insertion profile. Polyurethane elastomers were used to produce the graft and to coat the metallic struts of the stent to render it in vivo weldable. Results: The composition of the polyurethanes was fine-tuned, so to minimize the insertion profiles and optimize the welding properties and the clinical performance of the devices assembled. The stent and graft were deployed successively in pigs via a small 8F introducer, in situ welded, and the patency of the bi-component device was confirmed over a three-month post-implantation period. The strength of the stent/graft welded connection was fully retained, with no de-welding observed. Conclusions: The in situ welding strategy resulted in implantations that were easier to perform and markedly less injurious to tissues and organs, largely expanding the applicability of these ultra-minimally invasive procedures to especially frail segments of the population.

The Overlap of Diabetes and Osteoarthritis in American Populations.

Diabetes mellitus, a condition in which the body's ability to produce insulin is impaired, and osteoarthritis (OA), a painful degeneration of joint cartilage, are both serious conditions that affect millions of people in the United States (U.S.). Osteoarthritis is a chronic degenerative condition of the joint cartilage, affecting mainly the older population. The purpose of this paper is to find a connection, if any, between diabetes and osteoarthritis and if either condition can predispose an individual to the other. Not only can this review help to explain the co-existence of these two diseases, but it can also be used to look into a cure for patients in the future. After preliminary searches were done on PubMed, results were narrowed using specific keywords and similar risk factors among the two diseases. It was found that these two conditions are actually interrelated due to oxidative stress and pro-inflammatory cytokines. Seeing the high risk of developing one of these conditions and that obesity, one of the biggest risk factors for both diabetes and osteoarthritis, is at an all-time high in this country, a possible connection between the two of these diseases is very prevalent to look into. This information can be used to help correlate not only a better-targeted treatment but also lead to future research into why obesity is one of the biggest risk factors for both conditions.

Drug-Eluting Porous Embolic Microspheres for Trans-Arterial Delivery of Dual Synergistic Anticancer Therapy for the Treatment of Liver Cancer.

Blockage of blood supply while administering chemotherapy to tumors, using trans-arterial chemoembolization (TACE), is the most common treatment for intermediate and advanced-stage unresectable Hepatocellular carcinoma (HCC). However, HCC is characterized by a poor prognosis and high recurrence rates (≈30%), partly due to a hypoxic pro-angiogenic and pro-cancerous microenvironment. This study investigates how modifying tissue stress while improving drug exposure in target organs may maximize the therapeutic outcomes. Porous degradable polymeric microspheres (MS) are designed to obtain a gradual occlusion of the hepatic artery that nourishes the liver, while enabling efficient drug perfusion to the tumor site. The fabricated porous MS are introduced intrahepatically and designed to release a combination therapy of Doxorubicin (DOX) and Tirapazamine (TPZ), which is a hypoxia-activated prodrug. Liver cancer cell lines that are treated with the combination therapy under hypoxia reveal a synergic anti-proliferation effect. An orthotopic liver cancer model, based on N1-S1 hepatoma in rats, is used for the efficacy, biodistribution, and safety studies. Porous DOX-TPZ MS are very effective in suppressing tumor growth in rats, and induction tissue necrosis is associated with high intratumor drug concentrations. Porous particles without drugs show some advantages over nonporous particles, suggesting that morphology may affect the treatment outcomes.

A sequential treatment algorithm for infants with stage 4s neuroblastoma and massive hepatomegaly.

Infants with 4s neuroblastoma (NB) and massive hepatomegaly have a guarded prognosis and mortality approaches 30%. We report on eight patients with 4s NB and massive hepatomegaly treated with multiple modalities. One patient had spontaneous tumor regression. Three patients had progressive disease and responded to chemotherapy. Four patients progressed despite intravenous chemotherapy, of whom two died, and two were salvaged with hepatic intra-arterial chemoembolization. Treatment of infants with stage 4s NB with massive hepatomegaly should be individualized based on disease course. A sequential approach with observation, intravenous chemotherapy, and intra-arterial chemoembolization, may improve the outcome of these infants.

Between a rock and a hard place: clinical and imaging features of vascular compression syndromes.

Vascular compression syndromes are caused by the entrapment of vessels between rigid or semirigid surfaces in a confined anatomic space. Chronic entrapment may lead to arterial ischemia and embolism, venous stasis and thrombosis, and hematuria. These syndromes are usually seen in otherwise healthy young patients, among whom underdiagnosis is common. Most occurrences of vascular compression are associated with an underlying anatomic abnormality. In a small percentage of cases, other contributing factors, including repetitive microtrauma, may cause pathologic changes leading to the onset of pain and other symptoms of vascular and neural compression. Hence, the diagnosis must be based on both clinical and radiologic findings. Because some cases of vascular entrapment become symptomatic only when specific physical maneuvers are performed, dynamic diagnostic imaging methods are especially useful. Digital subtraction angiography has been the mainstay of imaging-based diagnosis for most vascular compression syndromes, but other methods (eg, color Doppler ultrasonography, computed tomographic angiography, and magnetic resonance angiography) are used with increasing frequency for initial diagnostic evaluation. Because vascular compression syndromes are caused by the external compression of vessels, endoluminal treatment alone is rarely adequate and surgical decompression is likely to be required for optimal and durable clinical benefit. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.321115011/-/DC1.

Radiologic imaging and intervention for gastrointestinal and hepatic complications of hematopoietic stem cell transplantation.

Hematopoietic stem cell transplantation (HSCT) is an increasingly available treatment option for patients with various oncologic, hematologic, and immunologic diseases. Although HSCT can be curative for some diseases, complications associated with this treatment limit its success and applicability. Gastrointestinal graft-versus-host disease (GVHD) and hepatic veno-occlusive disease are unique and deadly complications of HSCT. These diseases can mimic other HSCT complications, such as infection, hemorrhage, and hepatotoxicity with cholestasis, but GVHD and veno-occlusive disease require specific treatment. Early treatment improves the probability of treatment success. For these reasons, timely and accurate diagnosis is essential. Abdominal imaging and intervention play an important role in the early, minimally invasive diagnosis and treatment of GVHD and veno-occlusive disease. Imaging findings tend to be nonspecific, but common findings that may guide further management or establish a diagnosis in the clinical setting have been defined. In cases where the diagnosis is unclear and liver biopsy is required, image-guided transvenous liver biopsy may be a safer and more practical option than the transcutaneous approach. Image-guided interventions, including intraarterial steroid-injection therapy in severe, systemic steroid-refractory GVHD and transjugular intrahepatic portosystemic shunt placement in veno-occlusive disease with portal hypertension, have shown some promise in small, uncontrolled series. Larger, controlled studies are needed to define the role of these invasive procedures in this patient population.

Clinical applications of physical 3D models derived from MDCT data and created by rapid prototyping.

OBJECTIVE: In this article, we describe the production of physical models from CT data using rapid prototyping and present their clinical application. MDCT data acquisition of isotropic voxels and modern postprocessing techniques provide exquisite detail for clinicians and radiologists. CONCLUSION: In recent years, rapid prototyping technologies have provided new possibilities to visualize complex anatomic structures through the generation of physical models that can be used to assist with diagnosis, surgical planning, prosthesis design, and patient communication.

Transjugular kidney biopsy: enabling safe tissue diagnosis in high risk patients.

BACKGROUND: Transjugular kidney biopsy (TJKB) was first described in 1990. Indications for TJKB include uncorrectable bleeding disorders and conditions precluding the prone position. OBJECTIVES: To describe our initial experience with TJKB. METHODS: Between February 2008 and December 2009 all patients in whom percutaneous biopsy was contraindicated or unsuccessful underwent image-guided TJKB using a standard set with a 19 gauge core biopsy needle. Prospectively collected data included indication, number of needle passes, contrast dose, tissue yield, and complications. RESULTS: Twelve patients, age range 15-76 years (mean 55), underwent 14 TJKB procedures. Indications for the transjugular route included bleeding diathesis, dyspnea, ventral hernia, ascites, marked obesity, need for concomitant liver biopsy or concomitant insertion of tunneled dialysis catheter, discrepant kidney size, and failed percutaneous attempt. Thirteen biopsies were performed in 11 patients; in one patient TJKB was abandoned due to unfavorable renal vein anatomy. Four patients were premedicated with desmopressin and one with platelet transfusion due to prolonged bleeding time. Three to six passes (mean 3.8) were made per biopsy, with an overall yield of 9.6 +/- 8.2 glomeruli, providing a definite diagnosis in nine patients and a probable diagnosis in two. In two patients the first biopsy attempt yielded insufficient tissue, necessitating a repeat procedure. There were two minor bleeding episodes not requiring intervention. Serum creatinine was unchanged after the procedure and hemoglobin levels asymptomatically dropped by 0.3 +/- 1.0 g/dl within 48 hours, requiring no treatment. CONCLUSIONS: TJKB appears to safely allow adequate tissue diagnosis in patients at increased risk for complications from or contraindications to percutaneous renal biopsy.

Diagnostic and Management Difficulty of Bleeding Aorto-Duodenal Fistula Associated with Hodgkin's Lymphoma.

Primary aorto-enteric fistula (AEF) resulting from abdominal malignancy is a rare and often fatal complication. The few reports to date are mostly secondary to solid tumors. We present a case of a patient with refractory Hodgkin's lymphoma who developed life-threatening AEF. We describe the diagnostic and therapeutic efforts, requiring a multi-disciplinary team of interventional radiology, gastroenterology, and transfusion medicine, resulting in a favorable outcome. Importantly, we offer several insights regarding the identification and management of high-risk patients, with an emphasis on pre-treatment considerations and urgent diagnosis and intervention.

A novel technology for reversible fallopian tubal occlusion using a reverse thermo-responsive polymer-Preliminary results from a rabbit animal study.

OBJECTIVES: To determine if PF-88, a reverse thermo-responsive polymer designed to create a gel at body temperature and liquefy at a lower temperature (21°C) can reversibly occlude the fallopian tubes in rabbits. STUDY DESIGN: Mature female New Zealand White rabbits underwent laparotomy and placement of 22-gage catheter into the lumen of the distil uterine horns for evaluation of tubal patency by fluoroscopy using radio opaque contrast and treatment with PF-88. In the Acute Phase group (n = 5) after PF-88 treatment we immediately cooled the serosal surface of the tube with ice for 90 seconds to liquify the gel then reassessed patency. In the Survival Phase groups, animals recovered from the initial surgery and then underwent a second procedure for evaluation of tubal occlusion and reversibility at 4 (n = 3), 14 (n = 2), and 28 (n = 3) weeks after the initial procedure. We compared the histologic appearance of the treated fallopian tubes to untreated controls (n = 3). RESULTS: In the Acute Phase, we found all 10 fallopian tubes patent on initial evaluation, occluded following treatment with PF88, and patent following re-liquification by chilling. Animals in the Survival Group, all but one of the treated tubes appeared blocked at follow-up and patent following chilling. The treatment failure occurred in an animal in the 4-week group. Tubes treated with PF88 showed no histologic evidence of residual material or damage after removal of the polymer. CONCLUSION: The PF-88 reverse thermo-responsive polymer demonstrated the ability to reversibly block fallopian tubes for up to 28 weeks. IMPLICATIONS: The demonstration of reversible occlusion of the fallopian tube of rabbits using PF-88, a thermo-responsive reverse polymer, support additional studies to evaluate the potential of this polymer as a contraceptive in women.