Changes in Distensibility Index During an Incremental POEM Myotomy.

BACKGROUND: A longer myotomy for the treatment of achalasia is associated with worse gastroesophageal reflux disease despite palliating dysphagia. Recently, clinical outcomes have been correlated to the distensibility of the distal esophagus, which is measured intra-operatively using an endoscopic functional luminal image probe (EndoFLIP). We aimed to determine the minimum per oral endoscopic myotomy (POEM) length to allow for adequate distensibility index (DI). METHODS: A 6-cm myotomy conducted in 2-cm increments during POEM was performed for patients with achalasia I and II from 2017 to 2019. The EndoFLIP was used to measure the DI intra-operatively: (1) prior to intervention, (2) following creation of the submucosal tunnel, (3) following transection of the high-pressure zone (HPZ), (4) following the distal extension, and (5) following the proximal esophageal extension. RESULTS: A total of 16 patients underwent POEM. Ages ranged from 21 to 78 years, 10 were male, and 13 had type II achalasia. The median DI was 2.7 (1.4-3.6) mm2/mmHg prior to intervention; 2.4 (1.4-3.3) mm2/mmHg following the submucosal tunnel; 3.2 (1.6-4.4) mm2/mmHg following transection of the HPZ; 3.8 (2.6-4.5) mm2/mmHg following the gastric extension; and 4.5 (3.3-7.1) mm2/mmHg following the proximal extension. Our target range DI was achieved for 50% of patients after transection of the HPZ. CONCLUSIONS: Distensibility changed with each myotomy increment and fell within the target range for most patients following a 2-4-cm myotomy. This suggests that a shorter myotomy may be appropriate for select patients, and the use of the EndoFLIP intra-operatively may allow for a tailored myotomy length.

Semiautomated Glasgow-Blatchford Bleeding Score helps direct bed placement for patients with upper gastrointestinal bleeding.

OBJECTIVE: The Glasgow-Blatchford Bleeding Score (GBS) was designed to identify patients with upper gastrointestinal bleeding (UGIB) who do not require hospitalisation. It may also help stratify patients unlikely to benefit from intensive care. DESIGN: We reviewed patients assigned a GBS in the emergency room (ER) via a semiautomated calculator. Patients with a score ≤7 (low risk) were directed to an unmonitored bed (UMB), while those with a score of ≥8 (high risk) were considered for MB placement. Conformity with guidelines and subsequent transfers to MB were reviewed, along with transfusion requirement, rebleeding, length of stay, need for intervention and death. RESULTS: Over 34 months, 1037 patients received a GBS in the ER. 745 had an UGIB. 235 (32%) of these patients had a GBS ≤7. 29 (12%) low-risk patients were admitted to MBs. Four low-risk patients admitted to UMB required transfer to MB within the first 48 hours. Low-risk patients admitted to UMBs were no more likely to die, rebleed, need transfusion or require more endoscopic, radiographic or surgical procedures than those admitted to MBs. No low-risk patient died from GIB. Patients with GBS ≥8 were more likely to rebleed, require transfusion and interventions to control bleeding but not to die. CONCLUSION: A semiautomated GBS calculator can be incorporated into an ER workflow. Patients with a GBS ≤7 are unlikely to need MB care for UGIB. Further studies are warranted to determine an ideal scoring system for MB admission.

Impact of prior interventions on outcomes during per oral endoscopic myotomy.

BACKGROUND: Per oral endoscopic myotomy (POEM) is performed by accessing the submucosal space of the esophagus. This space may be impacted by prior interventions such as submucosal injections, dilations or previous myotomies. These interventions could make POEM more difficult and may deter surgeons during their initial experience. We sought to determine the impact of prior interventions on our early experience. METHODS: Prospective, single-center study of consecutive patients undergoing POEM. Patients were grouped according to their anticipated complexity: Group A: no prior interventions (N = 19); Group B: prior interventions such as submucosal injections and/or dilations (N = 11) and  Group C: sigmoidal esophagus, prior esophageal surgery, balloon dilation >30 mm (N = 8). We compared operative times, inadvertent mucosotomy rates, complications and short-term outcomes between groups. RESULTS: A total of 38 patients underwent POEM for achalasia subtypes: I (N = 9), II (N = 19) and III (N = 7). Three had other dysmotility disorders. Patients between the groups were similar. Operative times were similar between Group A and Group B but significantly longer for Group C (133 vs. 132 vs. 210 min, p = 0.001). Mucosotomy rates were highest in Group A (6/19) with 1 each in Group B/C (p = 0.46). One patient in Group A required an esophageal stent. Eckardt scores improved in all groups (6-1; 8-2; 6-0.5, p = 0.73), and postoperative GERD-HRQL scores were similar. One patient underwent laparoscopic myotomy for persistent symptoms with no improvement, and one patient underwent esophagectomy for a sigmoid esophagus and persistent symptoms despite adequate myotomy. CONCLUSION: A prior intervention does not seem to impact short-term clinical outcomes with POEM. Patients who had submucosal injections or small caliber dilations are similar to patients with no prior inventions; however, patients with a sigmoid-shaped esophagus and/or a prior myotomy require nearly double the operative time. Endoscopists undertaking POEM should consider these during their learning curve.

A Matched Comparison of Per Oral Endoscopic Myotomy to Laparoscopic Heller Myotomy in the Treatment of Achalasia.

BACKGROUND: Per oral endoscopic myotomy (POEM) is increasingly utilized to treat patients with achalasia. Early results have demonstrated significant improvement of symptoms, but there are concerns about postoperative reflux. With only limited comparative data available, we sought to compare POEM to laparoscopic Heller myotomy (LHM) with partial fundoplication. METHODS: This is a retrospective review of 42 POEM and 84 LHM patients undergoing primary myotomy for achalasia. Patients were matched by achalasia type, by Eckardt and dysphagia scores, and by quality of life (QOL) metrics. Analysis at 6-12-month follow-up evaluated these metrics, PPI use, pH, manometric, and endoscopic data. RESULTS: We matched 25 patients with achalasia types I (6), II (13), and III (6). Follow-up was longer for LHM at 158.1 (36.5-272.9) weeks versus 36.2 (22.2-41.2) weeks (p = 0.001). Eckardt scores, QOL metrics, and dysphagia significantly improved in both groups. DeMeester scores and total percent time less than 4 were abnormal in both groups and comparable (p = 0.925 and p = 0.838). Esophagitis was seen in 53.4 % (POEM) and 31.6 % (LHM) (Yates' p = 0.91), and PPI use was equivalent at 36 %. CONCLUSION: Early clinical outcomes are excellent with POEM and comparable to the standard of care LHM. Long-term follow-up is required as concerns for reflux persist.

International multicenter experience with an over-the-scope clipping device for endoscopic management of GI defects (with video).

BACKGROUND: The over-the-scope clip (OTSC) provides more durable and full-thickness closure as compared with standard clips. Only case reports and small case series have reported on outcomes of OTSC closure of GI defects. OBJECTIVE: To describe a large, multicenter experience with OTSCs for the management of GI defects. Secondary goals were to determine success rate by type of defect and type of therapy and to determine predictors of treatment outcomes. DESIGN: Multicenter, retrospective study. SETTING: Multiple, international, academic centers. PATIENTS: Consecutive patients who underwent attempted OTSC placement for GI defects, either as a primary or as a rescue therapy. INTERVENTIONS: OTSC placement to attempt closure of GI defects. MAIN OUTCOME MEASUREMENTS: Long-term success of the procedure. RESULTS: A total of 188 patients (108 fistulae, 48 perforations, 32 leaks) were included. Long-term success was achieved in 60.2% of patients during a median follow-up of 146 days. Rate of successful closure of perforations (90%) and leaks (73.3%) was significantly higher than that of fistulae (42.9%) (P < .05). Long-term success was significantly higher when OTSCs were applied as primary therapy (primary 69.1% vs rescue 46.9%; P = .004). On multivariate analysis, patients who had OTSC placement for perforations and leaks had significantly higher long-term success compared with those who had fistulae (OR 51.4 and 8.36, respectively). LIMITATIONS: Retrospective design and multiple operators with variable expertise with the OTSC device. CONCLUSION: OTSC is safe and effective therapy for closure of GI defects. Clinical success is best achieved in patients undergoing closure of perforations or leaks when OTSC is used for primary or rescue therapy. Type of defect is the best predictor of successful long-term closure.

Outcomes in patients who have failed endoscopic therapy for dysplastic Barrett's metaplasia or early esophageal cancer.

BACKGROUND: Endoscopic therapy (ablation ± mucosal resection) for esophageal high-grade dysplasia (HGD) or intramucosal carcinoma has demonstrated promising results. Little is known about patients who have persistent or progressive disease despite endotherapy. We compared patients who had successful eradication of their disease with those in whom endotherapy failed to try to identify factors predictive of failure and outcomes after salvage therapy. METHODS: We performed a single-institution retrospective review of patients treated with endotherapy from 2007 to 2012. RESULTS: Thirty-eight patients underwent endotherapy: 28 had successful eradication of their disease and endotherapy failed in 10 patients. Patients in whom endotherapy failed were more likely to have high-grade dysplasia (HGD) on initial endoscopy, nodules or ulcers, multifocal dysplasia, and persistent nondysplastic Barrett's metaplasia. Patients in whom endotherapy failed also underwent significantly more endotherapy sessions. Seven patients had persistent dysplasia or progression to cancer, and 3 patients had complete eradication of HGD but presented with intramucosal carcinoma an average of 15 months after eradication. The 10 patients in whom endotherapy failed underwent salvage therapy with esophagectomy (7 patients), definitive chemoradiotherapy (1 patient), and endotherapy (2 patients). Patients treated with esophagectomy were disease free at a mean of 25 months postoperatively. CONCLUSIONS: HGD on initial endoscopy, multifocal dysplasia, mucosal abnormalities, and failure to eradicate nondysplastic Barrett's metaplasia were associated with failure of endotherapy. Patients with these characteristics should be considered at higher risk for treatment failure, and earlier consideration should be given to esophagectomy if there is persistent, progressive, or recurrent neoplasia. Clinical outcomes are good, even after salvage therapy. Continued endoscopic surveillance is mandatory after successful endotherapy because of the risk of recurrent disease.

Spiral overtube-assisted colonoscopy after incomplete colonoscopy in the redundant colon.

BACKGROUND: A redundant colon can lead to incomplete colonoscopy. A variety of tools and techniques are available to complete colonoscopy but have limitations. OBJECTIVE: To determine the feasibility and safety of using a spiral overtube to complete a difficult colonoscopy. DESIGN: Retrospective review of a prospectively collected database. SETTING: Single tertiary institution. PATIENTS: Twenty-four patients with incomplete colonoscopy because of redundant colons underwent 26 procedures. The median age was 68 years, and 58% were men. INTERVENTIONS: All patients underwent colonoscopy performed with a 90-cm flexible threaded overtube and a variable-stiffness pediatric colonoscope. Four individuals (18%) required exchanging the colonoscope for an enteroscope. MAIN OUTCOME MEASUREMENTS: Successful cecal intubation, polyp identification and removal, time to reach the cecum, sedation needed, and complications. RESULTS: Cecal intubation was achieved in 22 patients (92%). Failures occurred in 2 patients with large hernias. The median time from insertion of the colonoscope to reaching the cecum was 14.5 minutes. All procedures were performed by using conscious sedation with midazolam (median dose 7 mg) and fentanyl (median dose 150 µg). Significant findings were encountered in 17 of 22 patients (77%) including 1 cancer and 2 advanced polyps. A median of 3 polyps was removed from each patient who had polyps. All noncancerous polyps were removed during the procedure. There were no complications. LIMITATIONS: Retrospective design, no control group, single center. CONCLUSION: Spiral overtube-assisted colonoscopy can enable cecal intubation in the majority of patients in whom standard colonoscopy fails because of a redundant colon.

The effect of periodic monitoring and feedback on screening colonoscopy withdrawal times, polyp detection rates, and patient satisfaction scores.

BACKGROUND: Previous studies showed a correlation between mean withdrawal times during screening colonoscopy and polyp/neoplasia detection rates. OBJECTIVES: To assess the effect of a monitoring and feedback program on withdrawal times, polyp/neoplasia detection rates, and patient satisfaction. DESIGN: Comparison of retrospective and prospective data. SETTING: Teaching hospital. PATIENTS: Asymptomatic adults undergoing screening colonoscopy. INTERVENTIONS: Monitoring and feedback program. MAIN OUTCOME MEASUREMENTS: Withdrawal times, polyp and neoplasia detection rates, and patient satisfaction scores. METHODS: We retrospectively reviewed 850 screening colonoscopies, recording withdrawal times, polyp findings, and patient satisfaction scores. All procedures were performed by 10 experienced gastroenterologists who were then informed that periodic confidential monitoring and feedback of withdrawal times, polyp detection rates, and satisfaction scores would be started. We then prospectively collected data on another 541 screening colonoscopies. We compared pre- and postmonitoring outcome measures. RESULTS: Overall, after monitoring had begun, there was an increase in mean withdrawal times (from 6.57 to 8.07 minutes; P < .0001), and polyp detection rates (from 33.1% to 38.1%; P = .04, significance removed by Bonferroni correction). Nine of the 10 endoscopists increased their withdrawal times significantly. There was a small, nonsignificant increase in the neoplasia detection rate (from 19.6% to 22.7%; P = .17), but no significant change in mean satisfaction scores. Across endoscopists, there was a moderate correlation (r = 0.63; P = .04, significance removed by Bonferroni correction) between withdrawal times and polyp detection rates, but not between withdrawal times and satisfaction scores. LIMITATIONS: No randomization, possible response bias, confounding of intervention effects, and sample size limitations. CONCLUSIONS: Monitoring and feedback are associated with increases in mean withdrawal times and polyp detection rates, but not patient satisfaction scores. Neoplasia detection rates showed a statistically nonsignificant trend toward an increase.

Recent advances in the use of stents for esophageal disease.

The use of self-expanding metal esophageal stents has evolved dramatically over the last 20 years. Stents themselves have morphed from simple open-mesh wire devices to a variety of partially and fully covered metal and plastic protheses designed to resist in-growth and migration. Indications include grown considerably from simply palliating malignant dysphagia to the treatment of benign conditions such as refractory strictures, perforations, and fistulas, bridging tumors through neoadjuvant therapy and even serving as support for mucosal healing after ablative therapies. This article describes the current experience with esophageal stenting for malignant and benign conditions and examines new innovations in stent design and applications.

Treatment of Barrett's esophagus with early neoplasia: a comparison of endoscopic therapy and esophagectomy.

BACKGROUND: Endoscopic therapies for early neoplasia in Barrett's esophagus may be a viable alternative to esophagectomy. OBJECTIVE: Our purpose was to compare endoscopic therapy and esophagectomy. DESIGN: Retrospective review from a single institution. SETTING: A medium-sized tertiary referral center. PATIENTS AND INTERVENTIONS: All patients with Barrett's esophagus and dysplasia or intramucosal carcinoma treated by photodynamic therapy (PDT), EMR, or argon plasma coagulation (APC) or esophagectomy with curative intent from May 1998 until November 2005. MAIN OUTCOME MEASUREMENTS: Survival, progression to cancer, eradication of dysplasia and Barrett's esophagus, major and minor complications, and costs were compared. RESULTS: Sixty-two patients who underwent endoscopic therapy (2 APC alone, 18 EMR + APC, 20 PDT + APC, and 22 EMR + PDT + APC) and 32 patients who underwent esophagectomy met the inclusion criteria. The 30-day mortality rate included 1 patient in the endotherapy group (2%) and none in the surgical group (P = .49). No deaths from esophageal cancer occurred in either group. Cancer developed in 6% of endotherapy patients and in none in the surgical cohort (P < .05). Major and minor complications occurred in 8% and 31% of endotherapy patients, respectively, and 13% and 63% of surgery patients (P = .50, P < .001). Median cost to date was $40,079 for endotherapy and $66,060 for esophagectomy (P < .001). LIMITATIONS: Retrospective study, relatively short follow-up, small numbers. CONCLUSIONS: Both endotherapy and esophagectomy can effectively treat high-grade dysplasia and intramucosal carcinoma associated with Barrett's esophagus. Endotherapy is associated with a higher risk of tumor progression, although this is uncommon. Esophagectomy incurs higher initial costs and results in more frequent minor complications but is usually curative.

Patient satisfaction scores for endoscopic procedures: impact of a survey-collection method.

BACKGROUND: Many endoscopy units administer patient satisfaction surveys. We hypothesized that the survey collection method would affect satisfaction scores. OBJECTIVE: To compare satisfaction scores obtained by using on-site (OS) surveys versus mail-back (MB) surveys. DESIGN: Quasi-randomization based on alternating weeks. SETTING: Teaching hospital. PATIENTS: Patients undergoing elective routine outpatient colonoscopy or upper endoscopy. INTERVENTIONS: Every patient was given an 11-question survey that asked about the patient's satisfaction with the nurses and the physician, wait times, the bowel-preparation process, patient education, procedural comfort, and sedation. Survey collection methods alternated weekly between an OS versus an MB method. MAIN OUTCOME MEASUREMENTS: Satisfaction scores on a Likert scale ranged from 1 (worst) to 7 (best). RESULTS: A total of 1698 subjects were included. The response rate was higher for the OS group (95%) than the MB group (62%). OS scores were significantly higher than MB scores for 5 of 11 questions, which concerned nurse satisfaction, physician satisfaction, bowel-preparation comfort, postprocedure education, and overall satisfaction (Bonferroni adjusted P < .05 for all). Younger patients gave lower scores than older patients for all questions, whereas women gave significantly lower scores than men for bowel-preparation satisfaction. LIMITATIONS: Lack of true randomization and formal validation of the satisfaction survey. CONCLUSIONS: Survey collection methods may bias not only response rates but also satisfaction scores. OS survey collection methods tend to result in higher satisfaction scores than MB methods. This bias should be noted when comparing scores among studies that used different survey collection methods.

Acute symptomatic small bowel obstruction due to capsule impaction.

BACKGROUND: Capsule impaction is a well-recognized complication of capsule endoscopy, with an incidence rate of 0.75% to 21%, depending on indication. There have been only 2 reported cases of capsule impaction causing symptomatic obstruction. OBJECTIVE: We present 3 cases of capsule impaction causing acute symptomatic obstruction and/or perforation. DESIGN: Case series. SETTING: Teaching hospital. PATIENTS: A 71-year-old woman had iron deficiency anemia in the setting of negative upper endoscopy, colonoscopy, enteroclysis, and enteroscopy. She developed severe abdominal pain, vomiting, and leukocytosis 20 hours after capsule ingestion. Emergent surgery was performed to remove the capsule, which was impacted at a previously undiagnosed ileal Crohn's stricture leading to perforation. A 64-year-old woman with Gardner's syndrome and a history of colectomy and subsequent episodes of small bowel obstruction underwent capsule endoscopy to define the site of obstruction. She experienced severe abdominal pain 24 hours after capsule ingestion, and emergent enteroscopy was done to retrieve the capsule, which was impacted at a previously undiagnosed annular mass in the distal duodenum. An 85-year-old man with episodic small bowel obstruction due to radiation enteritis underwent capsule endoscopy to localize the site of obstruction in anticipation of surgery. He returned with severe abdominal pain and vomiting 3 days later. At surgery, the capsule was found to be impacted at an ileal radiation stricture. MAIN OUTCOME MEASUREMENTS: Acute symptomatic bowel obstruction. RESULTS: These cases show that bowel obstruction and even possibly perforation can occur as a result of capsule impaction. CONCLUSIONS: The possibility of acute symptomatic small bowel obstruction should be included in the informed consent for capsule endoscopy.

Blinded comparison of esophageal capsule endoscopy versus conventional endoscopy for a diagnosis of Barrett's esophagus in patients with chronic gastroesophageal reflux.

BACKGROUND: Esophageal capsule endoscopy (ECE) is an alternative to EGD for Barrett's esophagus screening. A multicenter study found ECE to be safe, well tolerated, and accurate; however, a post hoc adjudication process was used that may have biased results. OBJECTIVE: To assess the accuracy of ECE for the diagnosis of Barrett's esophagus. DESIGN: Prospective and blinded, with no adjudication. PATIENTS: Screening patients with chronic gastroesophageal reflux and surveillance patients with known Barrett's esophagus. INTERVENTIONS: ECE followed by EGD in each subject. MAIN OUTCOME MEASUREMENTS: Sensitivity, specificity, and positive and negative predictive values of ECE for Barrett's esophagus by using EGD results, with histologic confirmation as the criterion standard. RESULTS: Ninety-six subjects were enrolled, of whom 90 (94%) completed the study, including 66 screening and 24 surveillance patients. ECE was 67% sensitive and 84% specific for identifying Barrett's esophagus, diagnosing 14 of 21 cases of biopsy-confirmed Barrett's esophagus. Positive and negative predictive values were 22% and 98%, respectively (calculated for screening patients only). Sensitivity for short- and long-segment Barrett's esophagus was similar. CONCLUSIONS: Our blinded, unadjudicated study shows that ECE had only moderate sensitivity and specificity for identifying Barrett's esophagus. ECE in its present form is not suitable as a primary screening tool for Barrett's esophagus but may be used in patients unwilling to undergo EGD. Inadequate visualization of the gastroesophageal junction may be the cause of suboptimal ECE accuracy; this may be improved by advances in ingestion protocol and capsule calibration.

Risk stratification for colon neoplasia: screening strategies using colonoscopy and computerized tomographic colonography.

BACKGROUND & AIMS: We developed a risk index to identify low-risk patients who may be screened for colorectal cancer with computerized tomographic colonography (CTC) instead of colonoscopy. METHODS: Asymptomatic persons aged 50 years or older who had undergone screening colonoscopy were randomized retrospectively to derivation (n = 1512) and validation (n = 1493) subgroups. We developed a risk index (based on age, sex, and family history) from the derivation group. The expected results of 3 screening strategies--universal colonoscopy, universal CTC, and a stratified strategy of colonoscopy for high-risk and CTC for low-risk patients--were then compared. Outcomes for the 3 strategies were extrapolated from the known colonic findings in each patient, using sensitivity/specificity values for CTC from the medical literature. Results were validated in the validation subgroup. RESULTS: In the derivation subgroup, universal colonoscopy detected 94% of advanced neoplasia and universal CTC detected only 70% and resulted in the largest total number of procedures and number of patients undergoing both procedures. The stratified strategy detected 92% of advanced neoplasia, requiring colonoscopy in 68% and CTC in 36% of patients, with only 4% having to undergo both procedures. In the validation subgroup, universal colonoscopy detected 94% and universal CTC detected 71% of advanced neoplasia, whereas the stratified strategy detected 89%, requiring colonoscopy in 64% and CTC in 40%. Unlike universal CTC, the stratified strategy was independent of assumptions for CTC sensitivity, specificity, and threshold for colonoscopy. CONCLUSIONS: The stratified strategy based on our risk index may optimize the yield of colonoscopic resources and reduce the number of patients undergoing colonoscopy.

Screening colonoscopy in very elderly patients: prevalence of neoplasia and estimated impact on life expectancy.

CONTEXT: Current guidelines do not include an upper age cutoff for colorectal cancer screening with colonoscopy. Although the prevalence of colonic neoplasia increases with age, life expectancy decreases. Thus, the benefit of screening colonoscopy in very elderly patients may be limited. OBJECTIVE: To compare estimated life-years saved with screening colonoscopy in very elderly vs younger persons. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study conducted among 1244 asymptomatic individuals in 3 age groups (50-54 years [n = 1034], 75-79 years [n = 147], and > or =80 years [n = 63]) who underwent screening colonoscopy at a US teaching hospital and clinic. MAIN OUTCOME MEASURES: Prevalence of various types of colon neoplasia; estimated gain in life expectancy, calculated as life expectancy--(life expectancy during polyp lag time + life expectancy after colorectal cancer diagnosis); and comparison of mean gain in life expectancy across the 3 groups. Life expectancy and mortality data were derived from life tables, previous studies, and national databases. RESULTS: The prevalence of neoplasia was 13.8% in the 50- to 54-year-old group, 26.5% in the 75- to 79-year-old group, and 28.6% in the group aged 80 years or older. Despite higher prevalence of neoplasia in elderly patients, mean extension in life expectancy was much lower in the group aged 80 years or older than in the 50- to 54-year-old group (0.13 vs 0.85 years). In sensitivity analysis, with longer polyp lag times the mean extension in life expectancy decreased more in the elderly than in the younger patients; alternatively, if it was assumed that a smaller proportion of adenomas progress to colorectal cancer, the mean extension in life expectancy decreased less in the elderly than in the younger patients. CONCLUSIONS: Even though prevalence of neoplasia increases with age, screening colonoscopy in very elderly persons (aged > or =80 years) results in only 15% of the expected gain in life expectancy in younger patients. Screening colonoscopy in very elderly patients should be performed only after careful consideration of potential benefits, risks, and patient preferences.