Functional maturity of the coagulation system in children: an evaluation using thrombelastography.

Background: Minimally invasive surgery has emerged as a major developmental trend in open-heart surgery worldwide over the past two decades. In Viet Nam, minimally invasive open-heart surgery in pediatric patients has been developing since 2014 and is currently performed at several major cardiovascular centers. This study reports the early outcomes of minimally invasive open-heart surgery in children at Cho Ray Hospital. Objective: To evaluate the early outcomes of minimally invasive cardiac surgery in pediatric patients at Cho Ray Hospital. Methods: A retrospective descriptive study was conducted by reviewing medical records of pediatric patients with congenital or acquired heart diseases who underwent surgery at the Pediatric Cardiac Surgical Intensive Care Unit, Cho Ray Hospital, from January 2020 to December 2025. Surgical approaches did not involve full median sternotomy and were performed with cardiopulmonary bypass support. Patients with isolated patent ductus arteriosus or isolated coarctation of the aorta were excluded. Results: A total of 40 pediatric patients underwent minimally invasive open-heart surgery, including 24 females (60%). The mean age at operation was 6.8 years (range: 3 months to 15 years), with a mean body weight of 25.5 kg (range: 4.7–65 kg). Preoperative diagnoses were ventricular septal defect in 23 patients (57.5%), atrial septal defect in 13 patients (32.5%), mitral regurgitation in 2 patients (5%), cor triatriatum in 1 patient (2.5%), and left atrial myxoma in 1 patient (2.5%). Minimally invasive surgical approaches included lower partial sternotomy in 11 patients (27.5%), right submammary thoracotomy in 18 patients (45%), and right vertical axillary thoracotomy in 11 patients (27.5%). The mean postoperative length of hospital stay was 19.8 days (range: 6–39 days). Early postoperative outcomes were favorable, with no in-hospital mortality, no reoperations, and no atrioventricular block requiring permanent pacemaker implantation (0%). Postoperative complications were infrequent, consisting of pneumothorax in 2.5% of patients and surgical site infection in 2.5%. Conclusion: In this study, the complication rate was very low, and no mortality was observed. Cardiac lesions were completely repaired, with no significant residual defects detected on postoperative echocardiography. Minimally invasive open-heart surgery in pediatric patients at Cho Ray Hospital demonstrated good and safe short-term outcomes. Minimally invasive open-heart surgery in pediatric patients performed at Cho Ray Hospital is safe and associated with favorable short-term outcomes.

Purpose: To review the current literature on the combined use of cataract surgery (or lensectomy) and vitrectomy in pediatric patients, with a focus on clinical indications, surgical techniques, outcomes, and complications across various pediatric ocular pathologies. Methods: A narrative review of published studies addressing the use of combined lensectomy and vitrectomy (LV) in pediatric patients was conducted. Conditions discussed include congenital cataracts, ectopia lentis, retinopathy of prematurity (ROP), retinal detachment (RD), and persistent fetal vasculature (PFV). Key surgical considerations, visual and anatomical outcomes, and postoperative complications were examined. Results: The literature search yielded a total of 160 articles, of which 43 met the inclusion criteria and were included in this review. Although lens-sparing vitrectomy (LSV) is preferred in many pediatric cases to preserve accommodation and reduce complications, combined LV is often necessary in advanced or complex diseases. Studies have shown that combined LV can achieve favorable anatomical outcomes, but functional visual recovery remains variable and is affected by factors such as patient age, baseline ocular anatomy, and disease severity. Postoperative complications such as glaucoma, visual axis opacification (VAO), and intraocular lens (IOL) dislocation are more frequent with combined procedures and require long-term follow-up and rehabilitation. Conclusions: Combined cataract surgery (or lensectomy) and vitrectomy may represent a valuable strategy in the management of complex pediatric ocular conditions, particularly when individualized to the clinical context. Tailored surgical approaches are essential to optimize anatomic and functional outcomes. Further prospective studies and harmonized multicenter registries are needed to develop evidence-based principles that can guide individualized surgical decision-making in this unique patient population.

Preoperative Fasting in Children

Laparoendoscopic single-site surgery (LESS) in pediatric patients has emerged as a viable alternative to standard laparoscopy. The aim of our investigation was to assess different surgical approaches for LESS, stratifying by weight. From March 2010 to April 2012 LESS was performed in 42 children. Children weighing below 10 kg underwent LESS through an umbilical incision using two 3-mm trocars and one 5-mm trocar. Patients above 10 kg were operated on using a metal multiuse single-site single port (X-Cone; Karl Storz Endoskope, Tuttlingen, Germany). Conventional straight laparoscopic instruments were used in all cases. Mean age at operation was 100 months (range, 0.25-207 months), and mean weight was 27 kg (range, 3.1-82 kg). Median operating time was 74 minutes (range, 36-300 minutes). Eighteen children underwent LESS using two 3-mm trocars and one 5-mm trocar; 1 case required two 5-mm trocars and one 10-mm trocar. Twenty-three patients were operated on with the multiuse device. All operations were carried out safely in a standard laparoscopic transperitoneal technique with full achievement of the surgical target. In none of the patients was an intraoperative complication noticed. Postoperatively two complications were noted, which resolved spontaneously. LESS for pediatric patients can be done safely and efficiently with even less trauma than in conventional laparoscopy irrespective of age and weight. However, different surgical approaches have to be considered as disposable single-site ports are not available for infants and small children. To decrease operative expenses, conventional multiuse trocars and a multiuse single-site port were used with conventional laparoscopic instruments.

Turbinate surgery in pediatric patients: A worldwide survey

The authors sought to validate magnetoencephalography spike sources (MEGSSs) in neuronavigation during epilepsy surgery in pediatric patients. The distributions of MEGSSs in 16 children were defined and classified as clusters (Class I), greater than or equal to 20 MEGSSs with 1 cm or less between MEGSSs; small clusters (Class II), 6 to 19 with 1 cm or less between; and scatters (Class III), less than 6 or greater than 1 cm between spike sources. Using neuronavigation, the MEGSSs were correlated to epileptic zones from intra- and extraoperative electrocorticography (ECoG), surgical procedures, disease entities, and seizure outcomes. Thirteen patients underwent MEGSSs: nine had clusters; two had small clusters, one with and one without clusters; and three had scatters alone. All 13 had scatters. Clusters localized within and extended from areas of cortical dysplasia and at margins of tumors or cystic lesions. All clusters were colocalized to ECoG-defined epileptic zones. Four of 10 patients with clusters and/or small clusters underwent complete excisions, and six underwent partial excision with or without multiple subpial transections. In the three patients with scatters alone, ECoG revealed epileptic zones buried within MEGSS areas; these regions of scatters were completely excised and treated with multiple subpial transections. Coexisting scatters were left untreated in nine of 10 patients. Postoperatively, nine of 13 patients were seizure free; the four patients with residual seizures had clusters in unresected eloquent cortex. Three patients in whom no MEGSSs were demonstrated underwent lesionectomies and were seizure free. Magnetoencephalography spike source clusters indicate an epileptic zone requiring complete excision. Coexisting scatters remote from clusters are nonepileptogenic and do not require excision. Scatters alone, however, should be examined by ECoG; an epileptic zone may exist within these distributions.

Read the full review for this Faculty Opinions recommended article: Six percent hydroxyethyl starch 130/0.4 (Voluven®) versus 5% human serum albumin for volume replacement therapy during elective open-heart surgery in pediatric patients.

Background: In pediatric and adolescent patients with medial meniscal ramp lesions (MMRLs) undergoing anterior cruciate ligament reconstruction (ACLR), the presence of concomitant lateral meniscal tears (LMTs) are not well-characterized. Purpose: To describe the characteristics and surgical management of concomitant LMTs in pediatric and adolescent patients undergoing MMRL repair during primary ACLR. Study Design: Case series; Level of evidence, 4. Methods: Patients <18 years old who underwent an MMRL repair during primary ACLR at 5 institutions from 2013 to 2025 were included. All MMRLs were diagnosed arthroscopically and defined as a partial or complete peripheral vertical/longitudinal tear of the posterior horn of the medial meniscus at or ≤3 mm from the meniscocapsular junction. The presence, location, and surgical management of arthroscopically identified concomitant LMTs were gathered from the operative reports. Lateral meniscus root tears (LMRTs) were categorized using the LaPrade classification. Patients with and without concomitant LMT at the time of MMRL repair during primary ACLR were compared. Results: In total, 189 pediatric and adolescent patients underwent an MMRL repair during primary ACLR at a mean age of 16.1 ± 1.4 years (range, 12.0-17.9 years). Concomitant LMTs were arthroscopically diagnosed in 122 (65%) patients, of which 38 (31%) were missed on the initial preoperative magnetic resonance imaging (MRI) report. Surgically, the majority of concomitant LMTs (67%) were treated with repair while 27% were treated with partial meniscectomy or observation (6%). LMTs were most frequently localized to the posterior horn (61%) or posterior root (27%). The most common LMT morphology was vertical/longitudinal (41%), followed by LMRTs (25%), complex nonroot tears (15%), radial tears (12%), and bucket-handle tears (4%). Of the 31 LMRTs identified, type 4 complex oblique root tears were most prevalent (65%), followed by type 2 complete radial root tears (26%), type 1 partial stable root tears (6%), and a type 5 bony root avulsion (3%). Significant risk factors associated with the presence of a concomitant LMT included male sex (odds ratio [OR], 1.9; 95% CI, 1.0-3.7; P = .044) and obesity (OR, 2.5; 95% CI, 1.0-6.1; P = .046). Conclusion: In this multicenter study, 65% of pediatric and adolescent patients undergoing MMRL repair during primary ACLR had a concomitant LMT and the majority were localized to the posterior horn and posterior root. As 31% of concomitant LMTs were missed on preoperative MRI, the posterior aspect of the lateral meniscus should be carefully evaluated at the time of surgery in pediatric patients with MMRLs. Nearly half of the concomitant LMTs identified in this cohort were LMRTs, complex tears, complete radial tears, or bucket-handle tears. Overall, surgeons should anticipate performing an additional lateral meniscal repair in nearly half of pediatric patients undergoing an MMRL repair during primary ACLR.

Although the negative effects of diabetes mellitus (DM) on operative outcomes in orthopaedic surgery is a well-studied topic in adults, little is known about the impact of this disease in children undergoing orthopaedic procedures. This study aims to describe the postoperative complications in pediatric orthopaedic surgery patients with DM. Pediatric patients with insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) were retrospectively identified while selecting for elective orthopaedic surgery cases from the American College of Surgeons National Surgical Quality Improvement Program Pediatric (ACS-NSQIP-Pediatric) database from 2012 to 2015. Univariate and multivariate analyses were performed to describe and assess outcomes when compared with nondiabetic patients undergoing similar procedures. Of the 17,647 patients identified, 105 (0.60%) had DM. Of those 105 patients, 68 had IDDM and 37 had NIDDM. The median age of DM patients was 13.8 years (11.9 to 15.5 y) and 37.1% of all DM patients were male. Comparing DM to non-DM patients, no significant differences were noted in the overall complications (1.4% vs. 1.9%, P>0.05) or reoperation rates (1.2% vs. 1.9%, P>0.05); however, DM patients did have a higher occurrence of unplanned readmissions (4.8% vs. 1.7%; P=0.037). Diabetic patients were statistically more likely to have an unplanned readmission with 30 days (adjusted odds ratio=3.34; 95% confidence interval=1.21-9.24, P=0.021). when comparing IDDM to NIDDM, there was no significant difference in outcomes. Comparing NIDDM to non-DM patients, there was an increased incidence of nerve injury (5.6% vs. 0.18%; P=0.023), readmission rate (11.1% vs. 1.8%; P=0.043), and reoperation rate (11.1% vs. 1%; P=0.013) in nonspinal procedures and an increased incidence of pulmonary embolism (10% vs. 0%; P=0.002) in spinal arthrodesis procedures. NIDDM predicted longer hospital stays (adjusted odds ratio=1.49; 95% confidence interval=1.04, 2.14; P=0.028) compared with nondiabetic patients in extremity deformity procedures. The 30-day complication, reoperation, and readmission rates for NIDDM patients were higher than that of non-DM patients. Furthermore, NIDDM is a predictor of longer hospital stays while DM is a predictor of unplanned readmissions. No statistical differences were noted when comparing outcomes of NIDDM to IDDM patients. Level III.

Objectives: This study aimed to compare the postoperative risks and long-term effects between direct bypass surgery (DB) and indirect bypass (IB) surgery for pediatric patients with ischemic-type moyamoya disease (MMD).Method: Pediatric patients (under or equal to 18 years old) who were diagnosed as MMD and given surgical treatments at our center between 2009 and 2015 were retrospectively reviewed from a prospective database. Pediatric hemorrhagic-type MMD patients and those who did not undergo digital subtraction angiography (DSA) were excluded. Patients who underwent DB were matched with patients who underwent IB using 1:1 propensity score matching. Postoperative complications, recurrent ischemic stroke events and modified Rankin Scale (mRS) scores at the last follow-up were compared between the matched pairs.Results: A total of 223 pediatric patients were screened, and 138 patients (DB:34, IB:104) were considered for the propensity score match. Thirty four pairs were obtained. Nine patients had postoperative complications, including 6 (17.6%) in the DB group and 3 (8.8%) in the IB group (P = 0.476). The mean follow-up period was 71.9 ± 22.2 months for the DB group and 60.2 ± 24.3 months for the IB group (P = 0.041). Kaplan-Meier analysis showed a longer stroke-free time in the DB group than in the IB group (P = 0.025). At last follow-up, good neurological status (mRS ≤ 1) was achieved in 32 (94.1%) of the DB group and 34 (100.0%) of the IB group. MRS score at last follow-up were significantly lower than at time of admission (all pts: 1.09 ± 0.45 vs. 0.28 ± 0.51, P < 0.001; DB group: 1.12 ± 0.48 vs. 0.32 ± 0.59, P < 0.001; IB group: 1.06 ± 0.42 vs. 0.24 ± 0.43, P < 0.001).Conclusion: Both techniques were effective in improving the neurological status of pediatric ischemic-type MMD patients, and direct bypass surgery might be more superior in preventing recurrent ischemic strokes in the short-term.

Introduction: The objectives of this study were to assess the level of pre- and post-operative education received by paediatric surgery patients and their caregivers in Saudi Arabia and to examine the association between pre- and post-operative education and post-operative outcomes of paediatric surgery patients. Furthermore, our study aimed to explore the factors influencing the effectiveness of pre- and post-operative education in improving patient outcomes and to propose recommendations for optimising pre- and post-operative education programmes for paediatric surgery patients in Saudi Arabia. Methodology: To achieve the study objectives, a cross-sectional survey was conducted in multiple hospitals in Saudi Arabia on a convenience sample of paediatric surgery patients and their caregivers. The data were collected through structured interviews and questionnaires assessing the level of pre- and post-operative education, patient outcomes and satisfaction. Statistical analysis was conducted using SPSS 28.0. The relationships between variables were explored using linear regression, establishing associations between pre-operative education and post-operative outcomes. Multivariate linear regression examined factors influencing pre-operative education. Results: The study included 1170 participants from various demographic backgrounds in Saudi Arabia. The age distribution of participants was as follows: 18–24 years (18.7%), 25–34 years (8.4%), 35–44 years (29.0%), 45–64 years (36.4%), 65 years (3.7%) and under 18 years (0.9%). The gender distribution was nearly balanced with 45.8% of females and 51.4% of males. The majority of participants held a bachelor’s degree (55.1%). The majority (82.2%) of participants lived in urban areas. This study found a positive association between comprehensive pre- and post-operative education and improved patient outcomes, including reduced post-operative complications and higher satisfaction scores. Pre-operative education played a significant role in alleviating concerns or fears about the surgery (86.9%) and in helping participants understand their child’s recovery process (86.9%). Conclusion: The study findings highlight the effects of pre- and post-operative education outcomes on paediatric surgery patients in Saudi Arabia. The results demonstrated the significance of pre- and post-operative education in reducing parental anxiety and concerns about their child’s surgery, promoting recovery understanding and enhancing patient satisfaction. Improving the quality of care and education is recommended to decrease complication and enhance surgery outcomes.

BackgroundAcute kidney injury (AKI) is a common postoperative complication in pediatric patients undergoing cardiac surgery and associated with poor outcomes. Dexmedetomidine has the pharmacological features of organ protection in cardiac surgery patients. The aim of this meta-analysis is to investigate the effect of dexmedetomidine infusion on the incidence of AKI after cardiac surgery in pediatric patients.MethodsThe databases of Pubmed, Embase, and Cochrane Library were searched until April 24, 2022 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RevMan 5.3 was used to perform statistical analyses.ResultsFive relevant trials with a total of 630 patients were included. The pooled result using fixed-effects model with OR demonstrated significant difference in the incidence of AKI between patients with dexmedetomidine and placebo (OR = 0.49, 95% CI: [0.33, 0.73], I2 = 0%, p for effect = 0.0004). Subgroup analyses were performed based on congenital heart disease (CHD) types and dexmedetomidine intervention time. Pooled results did not demonstrate considerable difference in the incidence of AKI in pediatric patients receiving intraoperative (OR = 0.53, 95% CI: [0.29, 0.99], I2 = 0%, p for effect = 0.05) or postoperative dexmedetomidine infusion (OR = 0.56, 95% CI: [0.31, 1.04], p for effect = 0.07), but a significant difference in patients receiving combination of intra- and postoperative dexmedetomidine infusion (OR = 0.27, 95% CI: [0.09, 0.77], p for effect = 0.01). Besides, there was no significant difference in duration of mechanical ventilation (SMD: –0.19, 95% CI: –0.46 to 0.08, p for effect = 0.16; SMD: –0.16, 95% CI: –0.37 to 0.06, p for effect = 0.15), length of ICU (SMD: 0.02, 95% CI: –0.41 to 0.44, p for effect = 0.93) and hospital stay (SMD: 0.2, 95% CI: –0.13 to 0.54, p for effect = 0.23), and in-hospital mortality (OR = 1.26, 95% CI: 0.33–4.84, p for effect = 0.73) after surgery according to the pooled results of the secondary outcomes.ConclusionCompared to placebo, dexmedetomidine could significantly reduce the postoperative incidence of AKI in pediatric patients undergoing cardiac surgery with cardiopulmonary bypass (CPB), but the considerable difference was reflected in the pediatric patients receiving combination of intra- and postoperative dexmedetomidine infusion. Besides, there was no significant difference in duration of mechanical ventilation, length of ICU and hospital stay, or in-hospital mortality after surgery.

Background &amp; objective: The use of muscle relaxants is a routine in most of the pediatric surgeries. At the end of the surgery, the residual effect of the muscle relaxants needs to be reversed. In most of the countries the reversal agents used are neostigmine plus atropine. In the previous few decades sugammadex has been introduced for this purpose. We reviewed the available research regarding efficacy and safety of sugammadex compared with neostigmine in reversing rocuronium-induced neuromuscular blockade (NMB) among pediatric patients. Methodology: Using specific keywords, we comprehensively went through the potential articles, comparing efficacy and safety of sugammadex with neostigmine in reversing rocuronium-induced neuromuscular blockade (NMB) among pediatric patients. We searched Europe PMC, Cochrane Library, Scopus, Medline, and ClinicalTrials.gov sources until September 22, 2022. Outcomes were expressed in risk ratio (RR) and mean difference (MD). Results: A total of 17 randomized controlled trials (RCTs) were included. Our pooled analysis revealed that the use of sugammadex as NMB agent in pediatric population was associated with faster time to reach train of four (TOF) &gt; 0.9 [MD -10.32 min (95% CI -12.42, -8.23), P &lt; 0.00001] and shorter time of extubation [MD -9.40 min (95% CI -11.84, -6.96), P &lt; 0.00001] compared with neostigmine + atropine. Regarding safety, incidence of post-operative nausea vomiting (PONV) [RR 0.44 (95% CI 0.25 – 0.78), P = 0.005] and tachycardia [RR 0.13 (95% CI 0.04 – 0.42), P = 0.0006] was significantly lower among children receiving sugammadex than those who received neostigmine + atropine. Incidence of other adverse events did not differ significantly between the two groups. Conclusions: Based upon the results of our research, we conclude that sugammadex possesses higher efficacy and better safety than neostigmine to reverse rocuronium-induced NMB among pediatric populations. Abbreviations: NMB: neuromuscular blockade, NMBA: neuromuscular blocking agents, PMC: PubMed Central, RCT: randomized controlled trial, TOF: train of four Keywords: Sugammadex; Neostigmine; Neuromuscular Blockade; Pediatric; Meta-Analysis Citation: Waren K, Fuadi I, Lestari AP. Sugammadex versus neostigmine for neuromuscular blockade reversal after surgery in pediatric patients: a systematic review and meta-analysis of randomized clinical trials. Anaesth. pain intensive care 2025;29(5):393-404. DOI: 10.35975/apic.v29i5.2869 Received: May 09, 2024; Revised: October 26, 2024; Accepted: January 01, 2025

Due to the substantial improvement in survival among pediatric patients undergoing congenital heart surgery, reducing early and long-term morbidity is becoming the major focus of care. Blood transfusion is associated with worse postoperative outcomes after cardiac surgery. Acute normovolemic hemodilution (ANH) is a blood conservation strategy that aims to reduce allogenic blood transfusion during cardiac surgery. However, there are scant data regarding its efficacy for pediatric cardiac surgery patients. We designed a single-center, controlled, randomized, pilot trial in patients between 6 and 36 months old undergoing pediatric heart surgery. Patients were equally assigned to undergo ANH prior to initiation of cardiopulmonary bypass or to be managed per usual care. The primary end point was the amount of blood product transfused perioperatively. Secondary end points were markers of morbidity: postoperative bleeding, hematocrit, inotropic agents use, intensive care unit, and hospital stay. The analysis was by intention-to-treat. Estimates of differences between groups are presented with 95% CIs. Twelve pediatric heart surgery patients were randomized to each group, ANH and usual care. Baseline characteristics were similar between groups. Acute normovolemic hemodilution implementation did not result in a reduction in the administration of blood product transfused (difference between ANH and usual care among patients transfused = -1.4 mL [-29.4 to 26.6], P = .92). Secondary end points were not different between groups. In this small trial of pediatric cardiac surgery patients, ANH as a strategy to reduce blood component therapy was safe; however, the study failed to show a reduction in perioperative transfusion or other postoperative outcomes.

Background: Caudal block with the use of an adequate dose of bupivacaine, and combined with a general anesthesia (GA) provides intra-operative anesthesia and postoperative analgesia. No study has examined the use of 3 mg/Kg bupivacaine for intra-abdominal surgery in pediatric patients in clinical practice. Objective: Compare the effectiveness of three mg/Kg bupivacaine administered as 1.2 mL/Kg 0.25% bupivacaine and 1.5 mL/Kg 0.2% bupivacaine for caudal block in pediatric patients undergoing intra-abdominal surgery. Methods: In a randomized, double-blinded clinical trial, patients (age: 6 months -7 years) were randomly assigned into one of two groups (n= 40) to receive a caudal block with either 1.2 mL/Kg 0.25% bupivacaine (group A) or 1.5 mL/Kg 0.2% bupivacaine (group B), with morphine 50 μg/Kg. The effectiveness of intra-operative anesthesia, complications, and requirements for post-operative analgesia were evaluated. Results: Data were available for 74 pediatric patients. There were no significant differences between the two groups in baseline characteristics. Intra-operatively, the numbers of patients who required a rescue analgesic were comparable between the groups (67% in group A and 63% in group B). The numbers of patients who required a muscle relaxant were also comparable between groups (49% in group A and 57% in group B). The time from discontinuation of the volatile anesthetic to extubation was significantly shorter in group B (9.5±1.1 minutes) than group A (14.3±0.9 minutes), p &lt; 0.01. The time from initial caudal block to the first analgesic required in the recovery room was significantly longer in group B (202±45 minutes) than in group A (149±27 minutes). The time from the caudal block to the first analgesic required in the ward was significantly longer in group B (10.4±3.1 hours) than in group A (8.2±2.0 hours). Overall fentanyl requirements were comparable between groups, 52.5±2.0 μg in group A and 49.5±3.0 μg in group B. Conclusion: Caudal block by either 1.2 mL/Kg 0.25% bupivacaine plus morphine 50 μg/Kg or 1.5 mL/Kg 0.2% bupivacaine plus morphine 50 μg/Kg provided effectively equivalent intra-operative analgesia and surgical relaxation. However, a caudal block with 1.5 mL/Kg 0.2% bupivacaine plus morphine 50 μg/Kg provided superior prolonged analgesic advantages compared with 1.2 mL/Kg 0.25% bupivacaine plus morphine 50 μg/Kg in pediatric patients undergoing intra-abdominal surgery.