Surgical treatment of retrorectal tumors: a plea for a laparoscopic approach.

INTRODUCTION: Retrorectal tumors (RRTs) are rare and often surgically excised due to the risk of malignant degeneration and compressive or obstructive symptoms. The approach for excision has traditionally been based on tumor location and performed using either a transabdominal or perineal approach depending on the position of the tumor. The advent of minimally invasive surgery, however, has challenged this paradigm. Here, we determined the applicability and potential advantages of a laparoscopic transabdominal approach in a series of 23 patients with RRTs. MATERIAL AND METHODS: We included 23 patients presenting with RRTs treated at the Surgical Gastrointestinal Unit at Hospital de Sant Pau that were registered prospectively since 1998. The preoperative evaluation consisted of colonoscopy, CT scan and/or MRI, mechanical bowel lavage, and antibiotic therapy. Signed consent was obtained from all patients for a laparoscopic transabdominal approach unless the tumor was easily accessible via a perineal approach. In case of recurrence, a transanal endoscopic microsurgery (TEM) approach was considered. Surgical details, immediate morbidity, and short- and long-term outcomes were recorded. RESULTS: Of the 23 RRT cases evaluated, 16 patients underwent a laparoscopic transabdominal approach and 6 underwent a perineal approach. No patients required conversion to open surgery. In the laparoscopic transabdominal group, the mean operating time was 158 min, the average postoperative hospital stay was 5 days, and postoperative morbidity was 18%. Three patients had recurrent RRTs, two of the three underwent surgical reintervention. The third patient was radiologically stable and close follow-up was decided. CONCLUSION: Our results show that laparoscopic transabdominal excision of RRT is a safe and effective technique, offering the potential advantages of less invasive access and reduced morbidity. This approach challenges the traditional paradigm of excision of these infrequent tumors based solely on tumor location and offers a viable alternative for the treatment of these infrequent tumors.

Bowel Perforation after Extracorporeal Wave Lithotripsy: A Review of the Literature.

INTRODUCTION: Extracorporeal wave lithotripsy (ESWL) is considered a first-line treatment for renal and ureteral stones up to 10-20 mm in diameter. Complications are uncommon, with a reported rate of 0-6% in the literature. Bowel perforation has only been described in a few case reports but requires rapid diagnosis and treatment. METHODS: A review of the literature from PubMed/Medline, Embase, Cochrane, and Web of Science databases was performed including studies reporting bowel perforation secondary to ESWL between January 1990 and June 2022. RESULTS: We found 16 case reports of intestinal perforation in the literature. Although some patients had previously undergone abdominal surgery or had inflammatory intestinal disease, others were without comorbidities that could lead to complications. Abdominal pain was the main symptom and imaging was required to confirm the diagnosis, which usually necessitated a surgical intervention. As regards the ESWL technique, it appears that the combination of a high energy level and the prone position constitutes a risk factor for these rare complications. At the authors' centre, only one case has been reported among 24,000 ESWL procedures over 20 years: A 59-year-old female who underwent ESWL for a distal right ureteral stone presented acute abdominal pain and free intraperitoneal pelvic fluid on ultrasound. A CT scan revealed a small bowel perforation requiring open laparotomy with primary closure. CONCLUSIONS: In conclusion, although bowel perforation after ESWL is rare, progressive abdominal pain with tenderness at physical examination requires proper imaging evaluation to exclude bowel perforation and prompt intervention if required.

Impact of biliary drainage prior to pancreatectomy.

BACKGROUND: There is still a lack of clarity about the benefits of preoperative biliary drainage (PBD), which was introduced to improve the perioperative outcome in patients with obstructive jaundice caused by a periampullary tumour. The aim of this study was to determine whether operative and postoperative complications increase in patients undergoing PBD during pancreatoduodenectomy (PD). MATERIAL AND METHODS: Retrospective examination was made of patients who underwent PBD for a periampullary tumour in our hospital between 2006 and 2014. From these, the patients were identified who had PBD with endoscopic retrograde cholangiopancreatography and these patients were further separated into two groups, as one group of patients with plastic stents and the other group of patients with metallic stents. Patients with pancreas head cancer were also separated into two groups as those who were and were not applied with PBD. The preoperative, intraoperative and postoperative characteristics of the patients were evaluated. RESULTS: A total of 123 patients were retrospectively reviewed. Biliary stent placement with PBD was applied to 48 patients, of whom 31 had metallic stents and 17 had plastic stents. In general, there was no difference between the PBD and the non-PBD groups in respect of the preoperative, operative and postoperative results. When patients with tumour of the pancreas head only were examined, the rate of wound infection was higher in the PBD group and there was no difference in the other parameters. Moreover, there was no difference between the patients with metallic stents and those with plastic stents in respect of outcomes. CONCLUSIONS: With the exception of wound site infection, although no difference was observed between the PBD and the non-PBD groups based on intraoperative and postoperative complications, because of the distinctive inherent complications of PBD it is essential to manage such patients properly and to carefully select the patients for the PBD procedure.

Prone Versus Supine Position in Abdominoperineal Resection: Outcomes in the Laparoscopic Era.

Background: It is unclear whether the supine or prone approach for abdominoperineal resection (APR) influences outcomes. Methods: In a retrospective study of patients with rectal cancer who underwent curative laparoscopic APR from 2005 to 2018, we compared perioperative data, postoperative outcomes, oncological outcomes, and survival between the two approaches. Results: We recruited 123 patients (58 for the supine group and 65 for the prone group), with a median age of 72 (41-93) years. Mean follow-up was 67.4-45.7 months (28-169) in the supine group and 47.8-30.9 months (13-158) in the prone group (P = .026). Duration of surgery was longer in the prone group at 237 ± 52.3 minutes versus 210 ± 56.6 minutes in the supine group (P = .007). The incidence of tumor perforation during surgery was 9% in the supine group versus 3% in the prone group (P = .208). The incidence of perineal wound infection did not differ significantly between groups (supine 22% versus prone 20%, P = .93). The mesorectum was incomplete in 25% cases in the supine group and 14% cases in the prone group (P = .175). Circumferential resection margin positivity was 21% in the supine group and 14% in the prone group (P = .374). Local and distant recurrence was higher in patients with adenocarcinoma in the supine group at 10% and 31% versus 4% and 17% in the prone group (P = .177). Overall survival was higher in the prone group: 4% of patients died due to disease progression compared with 24% in the supine group (P = .034). Conclusions: Our results suggest that morbidity is similar with both laparoscopic techniques, but long-term outcomes seem better with the prone approach.

Presentación y seguimiento de poliposis adenomatosa familiar (PAF): diferencias entre las mutaciones APC y MUTYH / Presentation and Follow-up of Familial Adenomatous Polyposis: Differences Between APC and MUTYH Mutations

ANTECEDENTES: La poliposis adenomatosa familiar (PAF) es una patología hereditaria, caracterizada por la existencia de pólipos y cáncer en el colon. La PAF puede ser consencuencia de dos trastornos genéticos: El gen adenomatous polyposis coli (APC) o el gen mutación Y homólogo (MUTYH). Las diferencias clínicas y fenotipicas entre las dos alteraciones geneticas no estan claramente establecidas. MATERIALES Y MÉTODOS: Se realizó un análisis restrospectivo de las manifestaciones clínicas, criterios quirúrgicos, características histológicas, tipo de mutación y resultados a largo plazo de pacientes diagnósticados mediante análisis genéticos de poliposis adenomatosa familiar entre 1984 y 2018. RESULTADOS: De un total de 71 pacientes incluidos en el estudio, en 14 de ellos se identificó mutación del gen MUTYH y en 57, mutación del gen APC. A 60 pacientes se les realizó tratamiento quirúrgico, a la mitad de ellos se les practicó proctocolectomía y a la otra mitad, colectomía total. En pacientes con la mutación APC, el 63% presentó adenomas duodenales; el 61%, pólipos gástricos y el 54% tumor desmoide. De los pacientes con la mutación del gen MUTYH, el 21% presentó adenomas duodenales y al 21% se le diagnosticó pólipos gástricos. En el 21% de los pacientes con mutación del gen APC, el número de pólipos fue inferior a 100 y en el 64% de los pacientes que presentaron mutación del gen MUTYH se observaron más de 100 pólipos en el colon. No existió diferencias estadísticamente significativas entre lo grupos respecto a la proporción de pacientes con más de 100 pólipos. CONCLUSIÓN: Es importante valorar la afectación colónica y la extracolónica en pacientes con mutaciones genéticas asociadas a la PAF

BACKGROUND: Familial adenomatous polyposis is described as one of the common two types of genetic disorders: APC and MUTYH gene associated polyposis syndrome and the clinical differences between the two can sometimes be unclear. MATERIALS AND METHODS: A retrospective analysis and comparison was made of clinical, surgical, and histological criteria, mutation types and the long-term results of patients who underwent genetic analysis which resulted in the diagnosis of Familial Adenomatous Polyposis between 1984 and 2018. RESULTS: Of the total 71 patients included in the study, 14 were identified with the MUTYH gene, and 57 with the APC mutation. In patients with the APC mutation, 63% had duodenal adenoma, 61% gastric polyp and 54% had desmoid tumor. Of the patients with the MUTYH mutation, 21% had duodenal adenoma and 21% were diagnosed with gastric polyps. In 21% of the patients with APC mutation, the polyp count was <100, and 64% of those with the MUTYH mutation had >100 polyps in the colon No statistical difference was determined between the groups in respect of the proportion of patients with >100 polyps. CONCLUSION: The pre-operative genetic testing of patients with polyposis coli will be useful in determining the future clinical outcome and helpful in guiding an informed decision as to whether to apply surgical treatment. It is useful to determine the colonic and extra-colonic involvement of genetic mutation diseases in patients with Familial adenomatous polyposis

Presentation and Follow-up of Familial Adenomatous Polyposis: Differences Between APC and MUTYH Mutations. / Presentación y seguimiento de poliposis adenomatosa familiar (PAF): diferencias entre las mutaciones APC y MUTYH.

BACKGROUND: Familial adenomatous polyposis is described as one of the common two types of genetic disorders: APC and MUTYH gene associated polyposis syndrome and the clinical differences between the two can sometimes be unclear. MATERIALS AND METHODS: A retrospective analysis and comparison was made of clinical, surgical, and histological criteria, mutation types and the long-term results of patients who underwent genetic analysis which resulted in the diagnosis of Familial Adenomatous Polyposis between 1984 and 2018. RESULTS: Of the total 71 patients included in the study, 14 were identified with the MUTYH gene, and 57 with the APC mutation. In patients with the APC mutation, 63% had duodenal adenoma, 61% gastric polyp and 54% had desmoid tumor. Of the patients with the MUTYH mutation, 21% had duodenal adenoma and 21% were diagnosed with gastric polyps. In 21% of the patients with APC mutation, the polyp count was <100, and 64% of those with the MUTYH mutation had >100 polyps in the colon No statistical difference was determined between the groups in respect of the proportion of patients with >100 polyps. CONCLUSION: The pre-operative genetic testing of patients with polyposis coli will be useful in determining the future clinical outcome and helpful in guiding an informed decision as to whether to apply surgical treatment. It is useful to determine the colonic and extra-colonic involvement of genetic mutation diseases in patients with Familial adenomatous polyposis.

Colorectal Cancer Prognosis: The Impact of Signet Ring Cell.

BACKGROUND: The prognosis for patients with colorectal cancer shows variation. The characteristics of colorectal cancer patients with signet-ring cell carcinoma (SRCC) are still not clear. MATERIALS AND METHODS: A retrospective comparison was made of the data of signet-ring cell colorectal carcinoma patients operated on between 2009 and 2018 in respect of clinicopathological and operative results, morbidity, mortality, and long-term survival. RESULTS: The study included a total of 34 patients comprising 26 (76%) males and 8 (24%) females with a mean age of 58 ± 11.7 years. Incidence of SRCC was determined as 1.8%. Lymphovascular invasion was determined in 22 (64%) patients. Tumors were determined as stage T2 in 8 (32%) patients, stage T3 in 9 (36%), and stage T4 in 8 (32%). According to the TNM classification, 5 (14.7%) patients were diagnosed with stage 1, 7 (20.6%) with stage 2, 15 (44.1%) with stage 3, and 7 (20.6%) with stage 4. The mean follow-up period was 40.6 ± 30.4 months, and mean disease-free follow-up was determined as 33.1 ± 36.1 months. Fifteen (44.1%) patients died because of the disease. CONCLUSION: Although SRCC is a poor prognostic factor, it should be kept in mind when determining adjuvant therapies and prognosis of patients determined with advanced-stage SRCC.

Is Segmental Colon Resection an Alternative Treatment for Splenic Flexure Cancer?

Background: Optimal elective surgery for splenic flexure cancer is unclear. Three types of surgical treatment methods are commonly used, subtotal colectomy (STC), left hemicolectomy (LHC), and segmental colon resection (SCR), but consensus is lacking as to which is the optimal method. Materials and Methods: We retrospectively compared clinicopathological and operative results, morbidity, mortality, and long-term survival in patients with splenic flexure cancer who underwent surgery between 1998 and 2018. Results: The study included 124 patients in the study. Following retrospective evaluation of the database, patients were classified into one of three groups according to the surgical approach: (1) STC (n: 41), (2) LHC (n: 55), and (3) SCR (n: 28). No statistically significant differences were found between groups regarding operative results, hospital stay, pathological data, mortality, recurrence, or long-term survival outcomes. Conclusion: Our results suggest that surgical procedures such as STC and LHC have no statistically significant clinical benefits over less aggressive approaches such as SCR. We thus conclude that SCR seems both a safe and effective alternative for splenic flexure tumors.

What have we learned in minimally invasive colorectal surgery from NSQIP and NIS large databases? A systematic review.

BACKGROUND: "Big data" refers to large amount of dataset. Those large databases are useful in many areas, including healthcare. The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) and the National Inpatient Sample (NIS) are big databases that were developed in the USA in order to record surgical outcomes. The aim of the present systematic review is to evaluate the type and clinical impact of the information retrieved through NISQP and NIS big database articles focused on laparoscopic colorectal surgery. METHODS: A systematic review was conducted using The Meta-Analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. The research was carried out on PubMed database and revealed 350 published papers. Outcomes of articles in which laparoscopic colorectal surgery was the primary aim were analyzed. RESULTS: Fifty-five studies, published between 2007 and February 2017, were included. Articles included were categorized in groups according to the main topic as: outcomes related to surgical technique comparisons, morbidity and perioperatory results, specific disease-related outcomes, sociodemographic disparities, and academic training impact. CONCLUSIONS: NSQIP and NIS databases are just the tip of the iceberg for the potential application of Big Data technology and analysis in MIS. Information obtained through big data is useful and could be considered as external validation in those situations where a significant evidence-based medicine exists; also, those databases establish benchmarks to measure the quality of patient care. Data retrieved helps to inform decision-making and improve healthcare delivery.

Metástasis gastrointestinales de carcinoma pulmonar primario. Serie de casos y revisión sistemática de la literatura / Gastrointestinal metastasis from primary lung cancer. Case series and systematic literature review

El objetivo del presente estudio es describir las características clínicas y el manejo de los pacientes tratados en nuestra institución por metástasis GI de cáncer pulmonar primario; así como realizar una revisión sistemática de casos reportados en la literatura. Se realizó un análisis retrospectivo de una base de datos prospectiva y revisión sistemática de la literatura utilizando las normas MOOSE (Meta-analysis Of Observational Studies in Epidemiology). Se incluyeron 91 pacientes, 5 de la base de datos de nuestra institución y 86 de la base de datos PubMed usando las palabras claves «intestinal metastasis» y «lung cancer». La mediana de tiempo entre el diagnóstico de cáncer pulmonar y el diagnóstico de metástasis GI fue 2 meses, la mediana de supervivencia global fue 4 meses. Este grupo de pacientes presentan mal pronóstico. El tratamiento estándar no se encuentra bien establecido. Ninguno de los tratamientos descritos ha mostrado tener impacto significativo sobre la supervivencia

Aim of the present study is to report clinical characteristics and outcomes of patients treated in authors’ hospital for GI metastasis from primary lung cancer, and to report and analyse the same data concerning patients retrieved from a systematic literature review. We performed a retrospective analysis of prospectively collected data, and a systematic review using the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. Ninety-one patients were included, 5 patients from the authors’ hospital and 86 through PubMed database using the keywords "intestinal metastasis" AND "lung cancer". The median time between primary lung cancer diagnosis and GI metastasis diagnosis was 2 months and the median overall survival was 4 months. This group of patients present a poor prognosis and the gold standard treatment is not defined. None of the reported treatments had a significant impact on survival

Gastrointestinal metastasis from primary lung cancer. Case series and systematic literature review. / Metástasis gastrointestinales de carcinoma pulmonar primario. Serie de casos y revisión sistemática de la literatura.

Aim of the present study is to report clinical characteristics and outcomes of patients treated in authors' hospital for GI metastasis from primary lung cancer, and to report and analyse the same data concerning patients retrieved from a systematic literature review. We performed a retrospective analysis of prospectively collected data, and a systematic review using the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. Ninety-one patients were included, 5 patients from the authors' hospital and 86 through PubMed database using the keywords "intestinal metastasis" AND "lung cancer". The median time between primary lung cancer diagnosis and GI metastasis diagnosis was 2 months and the median overall survival was 4 months. This group of patients present a poor prognosis and the gold standard treatment is not defined. None of the reported treatments had a significant impact on survival.

Endovascular Management of Ureteroarterial Fistula: Single Institution Experience and Systematic Literature Review.

BACKGROUND: Ureteroarterial fistula (UAF) represents an uncommon complication after urological surgery; however, this is a well-documented condition in patients with predisposing risk factors. The aim of the present study is to report and analyze the endovascular management of a series of patients with UAF, treated in authors' hospital, and to report and analyze the same data concerning patients retrieved from a systematic literature review. METHODS: Authors conducted a retrospective analysis of prospectively collected data and a systematic literature review. The research was carried out through PubMed database searching the following keywords: "uretero arterial fistula" and "uretero iliac fistula." It includes only articles reporting the endovascular management. RESULTS: Forty-six articles were included in the present study for a total of 94 patients. Risk factors were as follows: chronic indwelling ureteral stents, pelvic surgery, radiotherapy, iliac artery pseudo-aneurysm, and chemotherapy. All patients had gross hematuria at presentation. Stent graft placement was performed in 89 patients, embolization in 5 patients, and iliac internal artery embolization combined with stent graft placement was performed in 24 patients. Four postprocedural complications were observed (4.2%). During a median follow-up of 8 months, 10 complications related to UAF were observed (10.6%): rebleeding (7 cases) and stent thrombosis (3 cases). Two patients died for causes related to UAF (2.1%): rebleeding (1) and retroperitoneal abscess (1). CONCLUSION: Based on the present data, endovascular treatment is feasible and safe with low postprocedural complications and mortality rate. Considering the increase in surgery and radiotherapy performed, UAF should be always debated in patients with massive hematuria.

HPV-related squamous cell carcinoma in a neovagina after male-to-female gender confirmation surgery.

Vaginoplasty by penile and scrotal skin inversion is a well-established technique for male-to-female gender confirmation surgery. In this setting, chronic inflammation and lacerations associated with history of human papillomavirus (HPV) infection may induce a high risk of malignant degeneration in the long term. A 78-year-old transgender woman was admitted with genital discomfort and neovaginal discharge. The patient's history revealed male-to-female gender confirmation surgery with construction of a neovagina by penile and scrotal skin inversion at 33 years of age. Physical examination of the genitalia revealed presence of fecal material, suggestive of recto-neovaginal fistula. A biopsy specimen was positive for well-differentiated HPV-related squamous cell carcinoma. Magnetic resonance imaging (MRI) showed a bulky mass in the posterior wall of the neovagina that infiltrated the urethra, prostatic gland and the anterior rectal wall. Following a multidisciplinary evaluation, we performed a definitive sigmoid colostomy and administered chemotherapy. Long-term follow-up seems advisable in patients after vaginoplasty due to the possibility of delayed development of cancer. Following biopsy, we consider MRI as the modality of choice to identify possible infiltration of the adjacent structures. As data regarding these lesions are scarce and management is complex, a multidisciplinary approach is recommended.

Diagnóstico y tratamiento de la enfermedad diverticular del colon derecho: revisión de conjunto / Diagnosis and management of right colonic diverticular disease: A review

El objetivo de esta revisión es definir las características clínico-patológicas y aclarar el tratamiento de la enfermedad diverticular del colon derecho. Es poco frecuente en Europa, Estados Unidos y Australia, y más común en Asia. Durante los últimos años, su incidencia ha aumentado en Occidente, con diferentes distribuciones entre poblaciones. Muchos estudios han mostrado que es difícil diferenciar antes de la cirugía los síntomas de presentación de esta enfermedad de los de la apendicitis, ya que los síntomas y signos son similares, por lo que no es infrecuente encontrarse con un diagnóstico incorrecto. Con estudios de diagnóstico por la imagen exactos es posible establecer un diagnóstico preoperatorio preciso a fin de evaluar una estrategia de tratamiento adecuada. Actualmente, el tratamiento de esta enfermedad no está bien definido, no se han propuesto recomendaciones claras y no se sabe si también se pueden aplicar las recomendaciones para la enfermedad diverticular del colon izquierdo. Varios autores han señalado que el tratamiento conservador es el mejor enfoque, incluso en caso de reincidencia, y que la cirugía solo estaría indicada en determinados casos

The aim of this narrative review is to define the clinical-pathological characteristics and to clarify the management of right colonic diverticular disease. It is rare in Europe, USA and Australia and more common in Asia. In the recent years its incidence has increased in the West, with various distributions among populations. Many studies have reported that it is difficult to differentiate the presenting symptoms of this disease from those of appendicitis before surgery, because the signs and symptoms are similar, so misdiagnosis is not infrequent. With accurate imaging studies it is possible to reach a precise preoperative diagnosis, in order to assess an accurate treatment strategy. Currently the management of this disease is not well defined, no clear guidelines have been proposed and it is not known whether the guidelines for left colonic diverticular disease can also be applied for it. Several authors have stated that conservative management is the best approach, even in case of recurrence, and surgery should be indicated in selected cases

Diagnosis and management of right colonic diverticular disease: A review. / Diagnóstico y tratamiento de la enfermedad diverticular del colon derecho: revisión de conjunto.

The aim of this narrative review is to define the clinical-pathological characteristics and to clarify the management of right colonic diverticular disease. It is rare in Europe, USA and Australia and more common in Asia. In the recent years its incidence has increased in the West, with various distributions among populations. Many studies have reported that it is difficult to differentiate the presenting symptoms of this disease from those of appendicitis before surgery, because the signs and symptoms are similar, so misdiagnosis is not infrequent. With accurate imaging studies it is possible to reach a precise preoperative diagnosis, in order to assess an accurate treatment strategy. Currently the management of this disease is not well defined, no clear guidelines have been proposed and it is not known whether the guidelines for left colonic diverticular disease can also be applied for it. Several authors have stated that conservative management is the best approach, even in case of recurrence, and surgery should be indicated in selected cases.

Laparoscopic sleeve gastrectomy in patients over 60 years: impact of age on weight loss and co-morbidity improvement.

BACKGROUND: Advanced age has traditionally been considered a relative contraindication to bariatric surgery due to increased perioperative risk and less weight loss. However, it is now being reconsidered in older patients after encouraging results in recent series and the increasing life expectancy. We compared operative and postoperative outcomes of laparoscopic sleeve gastrectomy in patients over 60 years with outcomes in younger patients. We also, analyzed the effect of bariatric surgery on improvement and resolution of co-morbidities in the older group. METHODS: From November 2008 to November 2013, 130 patients underwent laparoscopic sleeve gastrectomy. Of these, 28 patients (21.5%) were 60 years or older. Outcomes in terms of perioperative complications, short-term and medium-term weight loss, remission or improvement of co-morbidities and medication requirements were extracted from our prospective database. RESULTS: Short-term mortality was 0% and 30-day complication rate was similar in both groups (17.9% versus 17.6% according to Clavien-Dindo classification). At 12 months postsurgery, older patients had lost 49% percent of excess weight compared to 60% in the younger group (P = 0.012). At 2 years, the results were 45% versus 60%, respectively, with P = 0.015. At least 1 major co-morbidity improved in 65.2% of older patients. Before surgery, the older group took an average of 4.3 medications compared to 2.7 at 1 year after surgery (P<0.001). CONCLUSION: Laparoscopic sleeve gastrectomy is a safe and effective treatment for morbid obesity in people over 60 years, although younger patients show greater weight loss. Daily medication requirements and co-morbidities decrease significantly in older patients after this procedure.