Gas-forming Infection Research Articles

Subcutaneous Emphysema in the Lower Extremities—Always an Emergency? Complications From Minimally Invasive Surgery—A Case Report

BackgroundLower-extremity subcutaneous emphysema is an unusual presentation in the emergency department, and it is often associated with gas-forming bacterial infections that confer significant morbidity and mortality. Because the presence of subcutaneous emphysema in an extremity can be alarming, physicians often pursue aggressive diagnostic and therapeutic strategies to identify and treat the underlying cause. In some cases, however, subcutaneous emphysema does not represent a life-threatening medical condition. The source of the subcutaneous air may not always be immediately recognized and can lead to either over- or under-utilization of resources to direct patient care. Case ReportWe describe a case of bilateral lower-extremity subcutaneous emphysema after recent robotic surgery. Why Should an Emergency Physician Be Aware of This?As the role of minimally invasive surgery and the push for shorter hospitalizations continue to rise, we are likely to see an increase in patients with complications from such procedures in the emergency department setting. Familiarity with the potential complications of these procedures is essential to differentiating between life-threatening and non−life-threatening conditions.

Factitious subcutaneous emphysema in young woman

A 33-year-old woman presented to the emergency department be-cause of “pain and swelling in upper extremity” with no history of trauma and fever. She was a known case of diabetes mellitus for 12 years who was under insulin therapy. She had separated from her husband and was living alone. On physical examination, she was afebrile with no abnormality in general examination but had multiple local erythema on her left upper extremity skin with tenderness and crepitation. There were small red macules and papules over sites of erythema which were crusted in some areas. Her left hand x-ray (Figure 1) was significant for subcutaneous emphysema. All labora -tory studies were within normal limits. On further questioning, she had multiple admissions during the previous year with the same complaint and all the diagnostic workups were inconsequential. Since the patient was right-handed and all the presentations were on the left arm, and there were no signs of gas-forming infections or visceral perforations, the skin lesions were attributed to air injec -tion sites and the diagnosis of factitious subcutaneous emphysema was made.Isolated subcutaneous emphysema of an extremity is a rare fin-ding

Diagnosis of Gas Gangrene: Does a Discrepancy Exist between the Published Data and Practice

The Infectious Disease Society of America has defined gas gangrene as an infection caused by Clostridium species. However, in many clinical settings, soft tissue infections that produce subcutaneous gas have been diagnosed as gas gangrene without identification of the presence of Clostridium species. Instead, the diagnosis was based on clinical and radiographic findings. A chart review was performed of 25 consecutive patients treated at the Atlantic Health System for infections of the lower extremity that were diagnosed as gas gangrene. Wound cultures from the 25 patients grew 31 different species of bacteria. The most prevalent organism was Staphylococcus aureus, which accounted for 17 of 31 (54.84%) different organisms identified and 19.77% of 86 separate aerobic or anaerobic cultures. The most prevalent genus was Streptococcus, which accounted for 20 (64.52%) of the organisms identified and 23.26% of the cultures. The most prevalent anaerobic genus was Peptostreptococcus, which accounted for 8 (25.81%) of the organisms identified and 9.3% of the cultures. None of the cultures grew Clostridium species. These findings showed that gas-forming soft tissue infections of the lower extremity, commonly diagnosed as gas gangrene, are rarely caused by Clostridium species.

Medical therapy alone can be sufficient for bilateral emphysematous pyelonephritis: report of a new case and review of previous experiences

Bilateral emphysematous pyelonephritis (EPN) is an extremely uncommon, life-threatening gas-forming infection of renal parenchyma and its surrounding areas. Surgical treatment, including percutaneous catheter drainage and nephrectomy, has been advocated as the treatment of choice in most of the patients. However, nephrectomy is itself a hazardous intervention in an unstable septic patient. Whenever bilateral disease is present, the need for long-term renal replacement therapy is unavoidable. We present the clinical course of a lady who presented with bilateral EPN and was successfully managed by medical therapy alone. We also reviewed almost all published cases of bilateral EPN that had been managed medically.

Tissue-Conserving, yet Radical Surgery for Extensive Gas-Forming Soft Tissue Infections Arising from Perirectal Abscess: Report of a Case

Perirectal abscess is encountered commonly in surgical practice, and simple incision and drainage usually is sufficient. However, life-threatening sepsis may occur. In such instances, the high morbidity and mortality rates from the severe systemic inflammatory response syndrome (SIRS) associated with rapidly evolving necrotizing and gas-forming soft tissue infections are of major concern. Case report and review of pertinent literature. A rare case of extensive necrotizing fasciitis of the torso arising from a perirectal abscess, in which the principles of radical surgical debridement were adhered to while minimizing disfigurement, is reported in a 19-year-old female. In some cases, despite the life-threatening nature of necrotizing fasciitis, it is possible to minimize tissue loss without compromising patient survival. Planning of the patient's site rehabilitation for maximum cosmetic outcome commences at the time of surgical debridement and is especially important for the young patient.

Acute post-surgical bilateral orbital gas-producing infection — a case report and literature review

The presence of visible gas on radiography, computed tomography (CT), or magnetic resonance imaging (MRI) is associated with various pathological conditions, ranging from severe infections caused by gas-producing organisms to cutaneous and subcutaneous tissue disruption that allows an interface with the air [1]. A high index of suspicion surrounds the finding of gas because of the virulence of conditions such as gas gangrene and necrotizing fasciitis [1–12]. Gas dissecting into the orbital soft tissues as a result of bacterial activity is a rapidly progressive, extremely serious, life-threatening ophthalmological emergency [1–12]. Gas gangrene (myonecrosis) and necrotizing fasciitis can cause necrosis of tissues and systemic shock with multiorgan failure, sometimes within a matter of hours [1–3, 13]. It is well known that the usual causative organisms in gas-producing infection from a contaminated wound are clostridial species: Clostridium perfringens accounts for the majority of cases (over 80 %), while most other cases are caused by other Clostridium species [1–3]. Clostridial infection is always associated with necrosis, and very often associated with poor functional and anatomical outcome [1–4]. However, a variety of other non-clostridial organisms, both aerobes and anaerobes, may also produce infections in which gas is demonstrable: Escherichia coli, Proteus species, Pseudomonas aeruginosa, Bacteroides, Klebsiela pneumoniae, Prevotella species, Staphylococcus aureus, Peptostreptococcus species, Fusobacterium species, and Streptococcus pyogenes are only the species reported most often in the literature [2]. Non-clostridial infections may take various forms, which lead to difficulties in making accurate and prompt diagnoses and are also related to the confusion between gas gangrene and various (bacterial and nonbacterial) lesions that simulate gas gangrene. Aside from the fact that non-clostridial organisms usually involve subcutaneous tissues, they may also involve muscle and simulate clostridial myonecrosis [2, 3]. However, non-clostridial gas infections accompanied by gangrene are not very common, even in immunosuppressed individuals [2, 3]. Since the initial report by Chiari (1893), which concerned a non-clostridial gas-forming infection due to a colon bacillus in the gangrenous lower limb of a diabetic patient [4], fewer than 40 cases of non-clostridial gas-forming infections have been described. Only four such cases have been described in the orbit [5–7, 12], and these are quite different from the present case. With regard to the pathogenesis of gas bubbles of clostridial or non-clostridial etiology, they are liberated by the bacterial fermentation of glucose [4]. In addition, impaired microcirculation may also contribute to gas formation [3, 4]. It is also necessary to mention the benign, non-infectious presence of gas in the orbit, which is known as orbital emphysema. Orbital emphysema is a well-known entity that can arise from nose-blowing, tumor presentation, or after fractures of the orbital floor, and may be self-induced in psychiatric patients [15]. There are no research contracts or any kind of financial support (grants) for this study. No authors have any conflicts of interest.

Emphysematous cyst infection in autosomal dominant polycystic kidney disease

A 51-year-old man was admitted to our hospital with flank pain and fever. Peritoneal dialysis had been started for endstage renal failure secondary to autosomal dominant polycystic kidney disease (ADPKD) at the age of 45 years, and he was switched to hemodialysis because of ultrafiltration failure after 4 years. Two years later, he suffered from right flank pain and fever (38.5 C). Magnetic resonance imaging revealed marked enlargement of both kidneys with multilocular complicated cysts bilaterally (Fig. 1). Although blood culture did not identify a pathogenic organism, his fever subsided after 3 months of antibiotic therapy. Transcatheter arterial embolisation (TAE) was performed to reduce kidney volume bilaterally according to the previously reported method [1]. Severe bilateral flank pain and fever occurred from 12 h after TAE, but subsided by the fourth day. At 7 days after TAE, right flank pain and high fever recurred. Computed tomography disclosed multiple lesions (arrows) with airfluid levels throughout the right kidney (Fig. 2). Fluid aspirated from these cysts grew Escherichia coli that was resistant to multiple antibiotics except meropenem. However, his fever persisted despite treatment with meropenem. The white blood cell (WBC) count rose to 29,900/lL and C-reactive protein was 24.8 mg/dL. His albumin was 1.4 mg/dL, total cholesterol was 96 mg/dL, and he was not diabetic. Finally, right nephrectomy was performed. After surgery, his fever subsided, WBC declined to 6,700/lL, and CRP decreased to 1.1 mg/dL. Emphysematous infection of renal cysts in ADPKD is a potentially lethal condition that requires nephrectomy, like emphysematous pyelonephritis. This was the first case among a total of 812 patients receiving renal TAE from 1996. When gas-forming infection occurs in the collecting system as well as the renal parenchyma, emphysematous pyelonephritis is diagnosed, which is a life-threatening disorder. Sooraj et al. used the term emphysematous polycystic renal infection (EPRI) for emphysematous infection in ADPKD patients. It is also common in diabetics and post-transplant patients [2]. Escherichia coli and Clostridium perfringens have been reported to be the causative organisms. Hyperglycemia or an impaired host response to sepsis are considered to result in EPRI [2, 3]. The present patient was not diabetic, but had malnutrition with hypoalbuminemia and hypocholesteremia. His immunocompromized status due to malnutrition may have contributed to the occurrence of this condition. M. Yamanouchi (&) Y. Ubara K. Takaichi Nephrology Center, Toranomon Hospital, 2-2-2 Toranomon, Minato-ku, Tokyo 105-8470, Japan e-mail: masayuki.y@coast.ocn.ne.jp

Emphysematous Cystitis: Report of an Atypical Case

We report the atypical case of a nondiabetic 66-year old male with severe abdominal pain and vomiting who was found to have emphysematous cystitis. Of all gas-forming infections of the urinary tract emphysematous cystitis is the most common and the least severe. The major risk factors are diabetes mellitus and urinary tract obstruction. Most frequent causative pathogens are Escherichia coli and Klebsiella pneumoniae. The clinical presentation is nonspecific and ranges from asymptomatic urinary tract infection to urosepsis and septic shock. The diagnosis is made by abdominal imaging. Treatment consists of broad-spectrum antibiotics, bladder drainage, and management of the risk factors. Surgery is reserved for severe cases. Overall mortality rate of emphysematous cystitis is 7%. Immediate diagnosis and treatment is necessary because of the rapid progression to bladder necrosis, emphysematous pyelonephritis, urosepsis, and possibly fatal evolution.

Non‐surgical management of post‐cesarean uterine infection with marked myometrial gas formation

Gas in an infected organ generally indicates a severe infection, often requiring surgery; however, data are lacking as to post-cesarean gas-forming uterine infection. A 27-year-old Japanese primigravida underwent a difficult cesarean section, after which a high fever continued. Computed tomography (CT) revealed marked gas in the uterine anterior myometrium. Diagnosing this condition as post-cesarean uterine scar infection, we recommended surgical intervention, that is, hysterectomy or at least drainage; however, the patient refused it. Considering the patient's desire and lack of organ-failure signs, we employed intensive antibiotic treatment for 6 weeks. Serial CT indicated a gradual decrement in the gas amount and she recovered completely after 8 weeks. This case suggests that surgical procedure may not always be necessary for post-cesarean gas-forming uterine infection and CT may be useful to detect/follow this condition.

Recurrent Factitious Subcutaneous Emphysema: Report of a Complex Case in a Young Woman and a Literature Review

Subcutaneous emphysema (SE) can be caused by antecedent trauma, surgery, rupture of visceral organs or serious infection from gas-forming microorganisms. Factitious SE is very rare; only about a dozen cases have been reported. Most patients had an underlying psychiatric condition or relevant history. The diagnosis and management of factitious SE are challenging. We report a new case of factitious SE with a very complex clinical course. A 29-year-old woman was seen at consultation for recurrent attacks of painful soft tissue swelling, affecting her chest wall, abdomen and neck over several months. Factitious disease was suspected because of the negative medical history of identifiable visceral perforations or gas-forming infections and the presence of multiple bizarre linear scars on the arm. This was supported by finding multiple recent puncture marks on the neck, chest and upper extremities on close inspection. The patient's history was remarkable for multiple stressful events in her life, frequent job changes, substance abuse and suicide attempts. Psychiatric evaluation revealed adjustment disorder with depression and anxiety, cluster B personality with bipolar II disorder and substance abuse. During the 1-year period, she had 20 visits to our ER for attacks of SE affecting various parts of her body. This case illustrates that self-infliction should be suspected in a patient presenting with medically unexplained recurrent SE and a hollow history, and one should search for puncture marks to support the diagnosis.

Giant emphysematous cystitis in a patient with diabetic uraemia.

A 51-year-old woman with a history of diabetic uraemia under chronic haemodialysis presented with progressive low abdominal pain and dysuria for more than 1 week. She also had a low-grade fever with hypotension, and rapidly progressed to septic shock. Physical examination showed marked tenderness in the suprapubic area. Laboratory examination revealed that the white blood cell (WBC) count was 23 000 per cubic millimetre with segmented neutrophils 88% and band cells 10%. The urinalysis examination showed pyuria with 40 white cells per high-power field. A plain abdominal radiograph showed severe distended urinary bladder with diffuse cystic collections of gas within the urinary bladder wall (Figure 1A, arrows), and an abdominal computed tomographic scan helped confirm the diagnosis of emphysematous cystitis by curvilinear pockets of gas within the urinary bladder wall (Figure 1B, arrow). A urine culture of Escherichia coli was isolated. The patient was treated with broad-spectrum antibiotics and bladder drainage. Despite intensive care, she died due to multiple organ failure 5 days later. Fig. 1 Plain abdominal radiograph showing severe distended urinary bladder with diffuse cystic collections of gas within the urinary bladder wall (A, arrows), and an abdominal computed tomographic scan helped confirm the diagnosis of emphysematous cystitis by ... Emphysematous cystitis is a rare disease characterized by gas-forming organism infection with gas collections inside the urinary bladder wall. The predisposing risk factors are diabetes mellitus (>50%), recurrent urinary tract infections, neurogenic bladder and immunocompromised state, and female sex [1]. The most common causative organisms are E.coli, but other organisms including Enterobacteraerogenes and other fungal species are also reported. Clinical presentations are usually non-specific including dysuria, increased urinary frequency, pyuria and haematuria. The radiological assessment by an abdominal computed tomographic scan can clearly demonstrate curvilinear pockets of gas within the urinary bladder wall with high sensitivity and specific diagnostic rate [2]. Early diagnosis with aggressive broad-spectrum antibiotic therapy can lead to have favourable prognosis, whereas delay in diagnosis and treatment may lead to developing an overwhelming septic shock with high mortality rate. Conflict of interest statement. None declared.

Gene–environment mismatch in decompression sickness and air embolism

Decompression sickness causes injury and death in SCUBA divers when air bubbles obstruct the flow of blood. Platelets aggregate in response to gas and promote inflammation. Inflammation in decompression sickness may have its origin in the innate immune system's response to pathogens. Bubbles are often found in tissues during gas-forming infections and in infection-prone states. In these diseases, intravascular gas offers a signal of infection to immune cells. Platelet activation by gas may often accompany a beneficial immune response to pathogens. Pathologic bubble-platelet interaction in decompression illness may be an example of gene-environment mismatch.

Clinical and Epidemiological Features of Clostridium perfringens Bacteremia: A Review of 18 Cases over 8 Year-Period in a Tertiary Care Center in Metropolitan Tokyo Area in Japan

Clostridial sepsis has a very poor prognosis, owing to the life-threatening combination of shock and acute massive hemolysis. No papers have described the clinical features of clostridial sepsis cases in Japan. Therefore, we retrospectively examined the clinical features of patients with systemic inflammatory response syndrome (SIRS) from whose blood cultures Clostridium perfringens was isolated. Blood samples were obtained from SIRS patients and cultured between January 1, 2001 and June 30, 2009. The samples were retrospectively reviewed, and 18 samples were positive for C. perfringens. The medical records of these 18 patients were reviewed for age, gender, underlying disease, past illnesses, results of physical and laboratory testing, and radiographic data. All patients were diagnosed with SIRS. Fifteen patients (83.3%) were >65 years old -mean age, 75±2 years (range, 59-88 years). There were more men (13) than women (5). The blood cultures were obtained from patients in various wards: tertiary care center (8), emergency room (5), surgical ward (4), and medical ward (1). Hepatobiliary tract diseases such as gallbladder stones and hepatic carcinoma were the most frequent underlying diseases (8). Five patients died, resulting in an overall mortality rate at 30 days of 27%. In the non-survival group, patients presented with septic shock (4) and gas-forming infection (2), and with significantly lower fibrinogen levels than those in the survival group. Septic shock at initial presentation was significantly associated with 30-day mortality for C. perfringens infection. There were no specific characteristics among clinical features of C. perfringens infection accompanied with SIRS. This may indicate that, in emergency rooms, diagnosing and initiating appropriate treatment for C. perfringens infection may be considerably difficult. It is important to be especially vigilant in identifying patients with C. perfringens infection underlying SIRS, and accompanied by shock.

陰圧閉鎖療法が奏効した内頸静脈壊死および降下性縦隔炎を伴う深頸部膿瘍例

Serious complications may accompany deep-neck infection. A 42-year-old man having mediastinitis and a necrotizing internal jugular vein caused by a deep-neck gas-forming infection was treated with antibiotics, surgical debridement, and vacuum-assisted closure (VAC) therapy, followed by complete recovery. We found VAC is useful in successfully treating infected tissue.

Emphysematous cholecystitis

BACKGROUND: Emphysematous cholecystitis is life-threatening condition characterized by gas-forming infection of the gallbladder. It is mostly seems in old male patients with systemic, specially diabetes and vascular diseases. CASE REPORT: - A 30-year-old man without previous diseases was admitted because of right upper quadrant pain and nausea. On admission the patient was febrile (38.7o) with normal bilirubin levels. The white blood count was 26700/µl and reactive protein C was 470. Axial sections of single slice computed tomography imaging (section thickness 5 mm), revealed gallbladder wall enhancement after i.v. contrast, as well as dilatation of the gallbladder with intraluminal air. The patient underwent open cholecystectomy. The culture of the bile showed clostridium perfringes. The postoperative course of the patient was uneventful. CONCLUSION: This is a rare form of cholecystitis that carries a high mortality and usually present insidious clinical signs. CT is the most accurate imaging technique. Antibiotic therapy should begin quickly and include coverage of common pathogens, particularly Clostridia. Surgical intervention should take place as early as possible.

Emphysematous Cystitis

In Brief Objectives: Emphysematous cystitis is a rare, gas-forming infection of the urinary tract that classically occurs in older diabetic women. We described a combination of pregnancy and cesarean delivery, which predisposed our patient to glycosuria and inoculated coliform bacteria into the bladder causing emphysematous cystitis. Case: A 32-year-old African multigravida presented 17 days following an uncomplicated primary low transverse cesarean section with suprapubic crepitance. A computed tomography scan showed an enlarged bladder measuring 13.1 × 14.1 cm. The patient was diagnosed with emphysematous cystitis, then managed with intravenous antibiotics and transurethral drainage of air, purulent material, blood clots, and 1 L of urine. Discussion: Although there was no formal documentation of glycosuria in her medical records, we believe it is very likely this played a role in the pathogenesis of her emphysematous cystitis. It is possible that our patient experienced glycosuria by way of physiologic glycosuria of pregnancy, an undiagnosed serum glucose intolerance, or related to administration of dextrose-containing IV fluids during the cesarean. Conclusion: Emphysematous cystitis is a unique postcesarean complication, which may present in atypical populations postpartum. A case of a 32-year-old African multigravida presented 17 days following an uncomplicated primary low transverse cesarean section with suprapubic crepitance.

Gas-forming purulent pericardial effusion

A previously healthy 45-year-old woman presented with cardiac tamponade secondary to a gas-forming purulent pericardial effusion. Eight days previously, she presented to hospital with a pericardial effusion. A subxiphoid diagnostic pericardiocentesis yielded a clear strawcoloured fluid. Cultures grew group F streptococci and alpha-hemolytic streptococci, which are associated with normal oral flora. The patient’s condition worsened with increasing respiratory distress and hemodynamic instability. She was transferred to a cardiac centre, where she was diagnosed with cardiac tamponade. A chest x-ray revealed a tension pneumopericardium (Figure 1). A large air pocket (white arrows) and a clearly defined air-fluid level (black arrows) were seen on this image. Emergent diagnostic and therapeutic pericardiocentesis revealed 560 mL of purulent fluid growing prevotella, bacteroides, Streptococcus milleri and Streptococcus viridans. Both the bacteroides and anaerobic streptococci are causes of gas-forming infections. Figure 1 Bacterial pericardial effusions are primarily a complication of an infectious focus originating elsewhere in the body, arising by direct spread or hematogenous dissemination. A total of 26% to 47% of patients have an underlying systemic disease process such as rheumatoid arthritis or autoimmune pericarditis, creating a pericardial effusion that may become secondarily infected (1). In the present case, after extensive imaging and autoimmune investigations, no source of infection or concurrent disease was found. Bacterial purulent pericarditis is a rare diagnosis with a mortality rate of up to 100% if not diagnosed and treated emergently (2). Treatment with antibiotics and surgical drainage is integral to allow for a full recovery. The present patient responded promptly after appropriate antibiotics and surgical pericardial window, with dehiscence of adhesions. It can only be speculated how these specific bacteria invaded the pericardial space and it is postulated that equipment contamination or passage of the first pericardiocentesis needle through the bowel were potential sources.

A rare association of emphysematous pyelonephritis with unrecognized diabetes and polycystic kidney

Emphysematous pyelonephritis (EPN) is a rare, severe, gas-forming infection for which the treatment of choice is often an immediate nephrectomy, although many reports exist of conservative treatment of cases with antibiotic therapy and percutaneous drainage of abscesses. It usually occurs in diabetic patients and less frequently in subjects with an obstruction of the corresponding renoureteral unit; other predisposing factors are not common. We report here the case of a 51 year-old woman with a rare association of unrecognized diabetes and bilateral polycystic kidney disease who developed monolateral EPN. She had an emergency right nephrectomy and was admitted to Intensive Care Unit (ICU) for septic shock after surgery, requiring intensive resuscitation. The patient was managed with Coupled Plasma Filtration Adsorption (CPFA). Her clinical conditions rapidly improved and the hemofiltration was soon suspended. Urine and blood cultures were positive for the same Escherichia coli, which was susceptible to all tested antibiotics. The patient was transferred to the Nephrology Division and was discharged from the hospital without further dialysis after 34 days. This case report is somewhat unique because of the unusual association between undetected diabetes and polycystic kidney as predisposing factors of a severe infection of the urinary tract.

Gas-Forming Urinary Tract Infection

Emphysematous or gas-forming infections, a very small percentage of bacterial infections of the urinary tract, attract importance because of their life threatening potential. Herein, we report a 60-year-old Saudi female patient who was a known case of Diabetes mellitus for 15 years. She was admitted with left flank pain of 5 days duration, abdominal distension, nausea, vomiting and chills associated with increased frequency of urine, urgency, and dysuria. She had leukocytosis, high blood sugar, elevated urea and creatinine and pyuria. Urine culture grew Escherichia coli. Ultrasound and CT scan showed left pelvicalyceal dilatation and air in the left kidney and urinary bladder. She was treated with a prolonged parenteral antibiotic course, and insulin, with complete recovery.

Salmonella Emphysematous Pyelonephritis in a Nondiabetic and Non-Obstructive End-Stage Renal Disease Patient

Emphysematous pyelonephritis (EPN) is a rare, severe, and gas-forming infection of the kidney. EPN is common in patients with diabetes mellitus and/or urinary tract obstruction. EPN rarely occurs in patients with end-stage renal disease, and is rarely caused by non-typhoidal Salmonella. This is a case report of end-stage renal disease in a 28-year-old woman who refused regular hemodialysis. She presented with fever, abdominal pain and right flank pain. Unenhanced computed tomography showed air within the right kidney. Salmonella group D was isolated from the drainage. The patient was successfully treated with antibiotics and percutaneous catheter drainage. To our knowledge, this is the first case report in the literature of EPN caused by Salmonella in a patient with end-stage renal disease who did not have diabetes mellitus or urinary tract obstruction.