Postoperative Dumping Syndrome, Health-Related Quality of Life, Anxiety, Depression, and Eating Disturbances: Results of a Longitudinal Obesity Surgery Study.

INTRODUCTION: Given the lack of research on the relationship of post-surgery dumping syndrome and eating disturbances, the purpose of the present longitudinal study was to investigate whether dumping after obesity surgery is associated with pre-/postoperative eating disorder symptoms or addiction-like eating beyond the type of surgery, gender, health-realted quality of life (HRQoL) and anxiety/depressive symptoms. METHODS: The study included 220 patients (76% women) before (t0) and 6 months after (t1) obesity surgery (sleeve gastrectomy [n = 152], Roux-en-Y gastric bypass [n = 53], omega loop gastric bypass [n = 15]). The Sigstad Dumping Score was used to assess post-surgery dumping syndrome. Participants further answered the Eating Disorder Examination Questionnaire (EDE-Q), Yale Food Addiction Scale 2.0 (YFAS 2.0), Short-Form Health Survey (SF-12), and Hospital Anxiety and Depression Scale (HADS) at t0 and t1. RESULTS: The point prevalence of symptoms suggestive of post-surgery dumping syndrome was 33%. Regression analyses indicate an association of dumping with surgical procedure (bypass), female gender, reduced HRQoL, more anxiety/depressive symptoms, and potentially with binge eating but not with eating disorder symptoms in general or with addiction-like eating. CONCLUSION: The current study failed to show a close relationship between the presence of self-reported dumping syndrome and eating disorder symptoms or addiction-like eating following obesity surgery. Further studies with longer follow-up periods should make use of clinical interviews to assess psychosocial variables and of objective measures to diagnose dumping in addition to standardized self-ratings.

No addiction transfer from preoperative food addiction to other addictive behaviors during the first year after bariatric surgery.

OBJECTIVE: The aim of the present study was to investigate whether the remission of preoperative food addiction is associated with increases or new onset of other addictions within the first year following bariatric surgery. METHODS: One hundred and twenty-five bariatric surgery patients were assessed before surgery (t1) and at 6 months (t2) and 1 year (t3) follow-ups. The assessments included the Yale Food Addiction Scale 2.0 (YFAS 2.0) and standardized questionnaires to measure symptoms of problematic alcohol use, gambling disorder, internet-use disorder, buying-shopping disorder, hypersexual disorder and exercise dependence. RESULTS: Forty-nine (39.2%) patients were assigned to the food addiction (FA+ ) and 76 patients (60.8%) to the non-food addiction group (FA- ) based on their preoperative YFAS scores. Overall, BMI and symptoms of food addiction decreased significantly from baseline to follow-ups. Preoperative food addiction status was not associated with postoperative increases or new onset of other addictions. Elevated symptoms of buying-shopping disorder, internet-use and hypersexual behaviour at baseline in the FA+ -group decreased over time and were comparable to the FA- -group at follow-ups. CONCLUSION: The 'addiction transfer' or 'cross addiction' hypothesis was not supportive for alcohol addiction, gambling addiction or other behaviours that may be addictive. Further studies are needed that investigate larger samples and longer observation periods, as well as other substance-use disorders.

Food addiction and other addictive behaviours in bariatric surgery candidates.

OBJECTIVE: The present study investigated the association between food addiction (FA) and other addictive behaviours in 216 bariatric surgery candidates (91.7% class 3 obesity; 80.1% women; age Mdn = 44.00 years, range 18-73). METHOD: Assessment included the Yale Food Addiction Scale 2.0 (YFAS 2.0) and standardized self-report questionnaires to measure symptoms of disorders related to substance use (alcohol and nicotine) and behavioural addictions (gambling, Internet-use, buying, hypersexual disorders, and exercise dependence). RESULTS: Bivariate correlations indicated a moderate relationship of YFAS 2.0 FA symptoms with buying disorder symptoms and a weak association with Internet-use disorder symptoms. Fifty-nine patients (27.3%) met the YFAS 2.0 threshold for FA, 1.9% for alcohol use disorder, 6.0% for nicotine use disorder, 17.3% for buying disorder, 2.3% for Internet-use disorder, and 1.4% for hypersexual disorder. None of the patients scored above the respective questionnaire thresholds for gambling disorder or exercise dependence. Patients with versus without YFAS 2.0 FA diagnosis did not differ with regard to prevalence estimates of addictive behaviours. CONCLUSIONS: Clinical implications and potential limitations of the findings are discussed. Future studies should address the potential risk of postoperative addiction transfer using long-term follow-ups and controlled study designs.

Development and Evaluation of the Quality of Life for Obesity Surgery (QOLOS) Questionnaire.

BACKGROUND AND AIM: Even though health-related quality of life (HRQOL) is considered an important component of bariatric surgery outcome, there is a lack of HRQOL measures relevant for preoperative and postoperative patients. The objective of the current study was to develop a new instrument assessing HRQOL prior to and following bariatric surgery, entitled Quality of Life for Obesity Surgery (QOLOS) Questionnaire. METHODS: Topics for the QOLOS were initially generated via open-ended interviews and focus groups with 19 postoperative bariatric surgery patients. Qualitative analysis resulted in 250 items, which were rated by patients (n = 101) and experts (n = 69) in terms of their importance. A total of 120 items were retained for further evaluation and administered to 220 preoperative patients and 219 postoperative patients. They also completed a battery of other assessments to analyze issues of construct validity. RESULTS: Analyses resulted in a 36-item section 1 QOLOS form targeting both preoperative and postoperative aspects across seven domains (eating disturbances, physical functioning, body satisfaction, family support, social discrimination, positive activities, partnership) and a 20-item section 2 QOLOS form focusing on postoperative concerns only (domains: excess skin, eating adjustment, dumping, satisfaction with surgery). Subscales of both sections showed acceptable to excellent internal consistency (Cronbach's α 0.72 to 0.95) and good convergent and discriminant validity. CONCLUSION: The QOLOS represents a reliable and valid instrument to assess HRQOL in preoperative and postoperative patients. Future studies should test the questionnaire in larger samples consisting of patients undergoing different types of surgery.

Quantity-guided drain management reduces seroma formation and wound infections after radical lymph node dissection: results of a comparative observational study of 374 melanoma patients.

BACKGROUND: Lymphatic fistulas are common complications after lymph node dissections in melanoma patients. We investigated whether drain management could improve the patient's outcome. METHODS: Patients who underwent axillary or inguinal lymph node dissection (RALND or RILND) for malignant melanoma were recorded in a prospective database. Two different methods of drain management were compared. Either the drain was removed no later than the eighth postoperative day (period I, 2003-2007) or it was left in place until fluid flow was below 50 ml in 24 h for two consecutive days (period II, 2008-2011). The main outcome criterion was the incidence of seroma punctures after drain removal. RESULTS: 374 patients were analysed. The incidence of seroma punctures significantly decreased in period II. The number of patients with elevated lymphatic secretions rose by 41.3% (RALND) and 38.1% (RILND). With the exception of lymphatic fistulas, we observed significantly more local complications with need for treatment in period I (n = 104, 52%) than in period II (n = 31, 18%). In period II, the hospital stays after both procedures were significantly reduced. CONCLUSIONS: We conclude that quantity-guided drain management leads to a prolonged interval of drainage but is associated with a lower incidence of seroma formation and shorter hospital stay.

Health-Related Quality of Life, Anxiety, and Depression in Bariatric Surgery Candidates Compared to Patients from a Psychosomatic Inpatient Hospital.

BACKGROUND AND AIM: Past research indicated high psychiatric comorbidity and poor health-related quality of life (HRQOL) in patients seeking surgical treatment for obesity. This study investigated if preoperative bariatric surgery patients perceive equally poor HRQOL and increased levels of anxiety and depression as mentally ill patients. METHODS: The study included four groups: 192 bariatric surgery candidates (PRE, 71% women, BMI 48.35 ± 8.98 kg/m2), 96 psychotherapy inpatients with mental disorders (PSY, 77% women, BMI 27.12 ± 9.17 kg/m2), 103 postoperative bariatric surgery patients (POST, 78% women, BMI 30.38 ± 2.88 kg/m2), and a convenience sample of 96 non-clinical volunteers with pre-obesity or obesity grade 1 (CG, 52% women, BMI 29.22 ± 2.64 kg/m2). HRQOL was measured using the 12-item short form health survey (SF-12), and psychopathology was assessed with the hospital anxiety and depression scale (HADS). RESULTS: The PRE group exhibited the lowest physical HRQOL, and the PSY group the lowest mental HRQOL. The highest mental/physical HRQOL was reported by the POST group and the CG, without significant differences between these two groups. While the PSY group scored higher on HADS-anxiety scale than the PRE group, neither group differed with regards to symptoms of depression. The lowest levels of HADS-depression were found in the POST group and the CG. CONCLUSIONS: The present findings suggest that bariatric surgery candidates may suffer from equally high levels of depression as psychotherapy inpatients, but they perceive better mental well-being. Routine mental health evaluation should incorporate assessments for both psychopathology and HRQOL. TRIAL REGISTRATION: DRKS00009901.

Postoperative surgical complications after radical axillary lymph node dissection in melanoma disease result in increased pain.

Postoperative pain is one of the major problems caused by the operative trauma. We recorded the postoperative pain of patients who underwent a radical axillary lymph node dissection (RALND) to evaluate the quality of our standardized perioperative pain management program and the influence of surgical complications. Between August 2003 and December 2007, we registered the postoperative level of pain of 111 patients who underwent a therapeutic RALND, using a visual analog scale (VAS). Patients received standardized perioperative pain therapy according to level I of the World Health Organization (WHO) ladder of pain. We registered a VAS score of 10 in patients at rest during the first 3 postoperative days, but after mobilization of the arm, patients had significantly more pain (P < 0.0001). Patients with a postoperative surgical complication needed significantly more central analgesia to reach the same level of pain (P = 0.04) as patients without complication. Level I of the WHO ladder of pain is not enough for patients after an RALND. Patients with a postoperative complication do have increased pain, and use of only peripheral analgesia is insufficient.

The German registry for natural orifice translumenal endoscopic surgery: report of the first 551 patients.

OBJECTIVE: To analyze patient outcome in the first 14 months of the German natural orifice translumenal endoscopic surgery (NOTES) registry (GNR). SUMMARY BACKGROUND DATA: NOTES is a new surgical concept, which permits scarless intra-abdominal operations through natural orifices, such as the mouth, vagina, rectum, or urethra. The GNR was established as a nationwide outcome database to allow the monitoring and safe introduction of this technique in Germany. METHODS: The GNR was designed as a voluntary database with online access. All surgeons in Germany who performed NOTES procedures were requested to participate in the registry. The GNR recorded demographical and therapy data as well as data on the postoperative course. RESULTS: A total of 572 target organs were operated in 551 patients. Cholecystectomies accounted for 85.3% of all NOTES procedures. All procedures were performed in female patients using transvaginal hybrid technique. Complications occurred in 3.1% of all patients, conversions to laparoscopy or open surgery in 4.9%. In cholecystectomies, institutional case volume, obesity, and age had substantial effect on conversion rate, operation length, and length of hospital stay, but no effect on complications. CONCLUSIONS: Despite the fact that NOTES has just recently been introduced, the technique has already gained considerable clinical application. Transvaginal hybrid NOTES cholecystectomy is a practicable and safe alternative to laparoscopic resection even in obese or older patients.

Preemptive analgesia reduces pain after radical axillary lymph node dissection.

BACKGROUND: Analyzing prospective data of our melanoma patients, we registered a suboptimal pain score under mobilization after radical axillary lymph node dissection (RALND). We performed a randomized, double blinded clinical trial to investigate the effects of a preemptive Parecoxib analgesic during the perioperative course. MATERIALS AND METHODS: Between October 2006 and December 2007, 32 patients with stage III/IV melanoma underwent therapeutic RALND and were randomized into two groups. Patients received intravenously 40 mg Parecoxib or 0.9% normal saline solution 2 h before RALND. The postoperative treatment and analgetic regime was defined in the study protocol. Main outcome criterion was the pain under mobilization at the first postoperative morning registered via a visual analogue score. Minor criteria were the postoperative complications, fatigue, amount of analgesics, and the day of discharge. RESULTS: Patients receiving a preemptive analgesic had a better outcome after RALND. The pain after mobilization was significantly decreased at the first postoperative morning (P = 0.04). Patients had less fatigue as well (P = 0.05) and the amount of pain medication in the treatment group was reduced (P = 0.04). CONCLUSIONS: Preemptive application of Parecoxib enhances outcome after RALND. A preemptive analgesic with Parecoxib in the perioperative management after RALND of melanoma patients can be recommended.

Effects of cyclooxygenase inhibition on anastomotic healing following large bowel resection in a rabbit model--a randomized, blinded, placebo-controlled trial.

PURPOSE: We performed an experimental study in a rabbit model to investigate the effects of a selective Cox-2 inhibitor (Valdecoxib) on anastomotic healing following large bowel resection after 1 week. MATERIALS AND METHODS: Eighty New Zealand white rabbits were randomized into four groups and underwent a colon resection with end-to-end anastomosis. Group 1 (n = 20) was treated with Valdecoxib, group 2 with Metamizole (Novalgin), group 3 with Resveratrol (specific Cox-1 inhibitor), or a placebo vehicle with similar volume (group 4). Anastomotic healing was tested at the seventh postoperative day by measurement of the bursting pressure in vitro. Immunohistochemical staining of the anastomotic site was performed with polyclonal antibodies (CD31). RESULTS: There were no significant differences in anastomotic dehiscence, bursting pressure, or vessel density between the treatment and control groups. CONCLUSION: The application of Valdecoxib does not influence anastomotic healing or new vessel formation in the anastomotic region following large bowel resection.

Intraoperative application of fibrin sealant does not reduce the duration of closed suction drainage following radical axillary lymph node dissection in melanoma patients: a prospective randomized trial in 58 patients.

BACKGROUND: Patients suffering from malignant melanoma often require radical lymph node dissection of the axillary nodal basin. The effects of intraoperative application of fibrin sealant following radical axillary lymph node dissection (RALND) on the incidence of postoperative lymphatic secretion are discussed. To study the effect of intraoperatively applied fibrin sealant following RALND a randomized patient-blinded trial was carried out. METHODS: Fifty-eight patients with axillary lymph node metastases of malignant melanoma underwent therapeutic RALND and were randomized into two groups: 29 patients received 2 cc of fibrin glue intraoperatively and 29 patients were only irrigated with 0.9% saline. The amount of drainage was recorded every 24 h. The main outcome criterion was the duration of drain placement in the wound. Minor criteria were the total amount of fluid and the length of hospital stay. Statistical analysis was performed using Spearman's log-rank correlation and paired t-test. RESULTS: There was no significant difference between the nonfibrin group 5 days (range = 3.6-5.7 days) and the fibrin group 5 days (range = 4.1-8.5 days) (p = 0.701). The total amount of fluid for the nonfibrin group (410 cc, range = 362-727 cc) and that for the fibrin group (503 cc, range = 369-1098 cc) (p = 0.605) and the length of postoperative hospital stay of 6 days (range = 5.4-7) vs. 7 days (range = 5.9-10.7), respectively, were not different between both groups (p = 0.387). CONCLUSION: Considering our study results, we cannot recommend the use of 2 cc of fibrin glue intraoperatively in the prevention of lymphatic secretion in patients undergoing RALND for metastatic melanoma.

The ubiquitin- and proteasome-dependent degradation of COX-2 is regulated by the COP9 signalosome and differentially influenced by coxibs.

The cyclooxygenase-2 (COX-2) enzyme is induced upon inflammation and in neoplastic tissues. It produces prostaglandins that stimulate tumor angiogenesis and tumor growth. Therefore, destruction and/or specific inhibition of COX-2 should be an important aspect of future tumor therapy. Recently, clinical application of specific COX-2 inhibitors called coxibs became doubtfully because they produce serious renal and cardiovascular complications under long term application. The exact underlying mechanisms are poorly understood and the different effects of diverse coxibs are not explained. It has been demonstrated before that COX-2 is degraded by the ubiquitin (Ub) proteasome system (UPS). However, how ubiquitination is accomplished and regulated was unclear. An important regulator of the UPS is the COP9 signalosome (CSN), which controls the stability of many proteins. Here we show that the proteasome-dependent degradation of COX-2 in HeLa cell lysate and in HeLa cells was stimulated by curcumin, an inhibitor of CSN-associated kinases. These data suggest a function of the CSN in the degradation of COX-2. In addition, proteolysis of COX-2 was significantly accelerated by parecoxib, but not by celecoxib or rofecoxib. By density gradient centrifugation and immunoprecipitation we demonstrate that COX-2 physically interacts with the CSN. Moreover, COX-2 is associated with large complexes consisting of the CSN, cullin-RING Ub ligases and the 26S proteasome. Pulldown experiments with Flag-COX-2 revealed cullin 1 and cullin 4 as components of the large super-complexes. Cullin 1 and 4 are scaffolding proteins of Ub ligases that presumably ubiquitinate COX-2. Treatment of HeLa cells with parecoxib results in an accelerated degradation of endogenous COX-2 accompanied by an increase of COX-2-Ub conjugates. In HeLa cells parecoxib is converted to the selective COX-2 inhibitor valdecoxib. Addition of valdecoxib also stimulates COX-2 degradation in HeLa cells. We therefore conclude that valdecoxib specifically interacts with COX-2 and induces a conformation accessible for ubiquitination and degradation.

Re-endothelialization of punctured ePTFE graft: an in vitro study under pulsed perfusion conditions.

BACKGROUND: When used as arteriovenous (AV) shunts for haemodialysis, small diameter expanded polytetrafluoroethylene (ePTFE) grafts have a high failure rate in vivo. Attempts to improve graft patency are various, and focus on either improvement of implantation techniques or graft tissue engineering. The tissue engineering approach attempts to reproduce in grafts the properties of pristine vasculature. As shown in previous experiments, it is possible to grow on ePTFE grafts under shear stress in vitro an autologous endothelial cell layer, which will withstand physiological stress under in vivo conditions of blood flow. The aim of this study was to investigate in an in vitro model the regenerative potency of a tissue-engineered prosthetic vascular graft after repeated cannulation with a haemodialysis cannula. METHODS: Pig endothelial cells were harvested from an external jugular vein. Following processing of the endothelial cells, seven ePTFE grafts were coated with an inner cell layer and were kept under pulsed perfusion. Each graft was then cannulated three times with a standard shunt needle. The endothelium was then left to regenerate for a maximum of 48 h. The grafts were stained with haematoxylin/eosin before histological study. RESULTS: All grafts were endothelialized over the puncture sites within 48 h. Histological analysis revealed a confluent endothelial cell lining at each puncture site. Cell morphology and cell pattern over puncture sites were not different from randomly picked locations over the graft lumen. CONCLUSION: Our results underline the potential of endothelial tissue engineering in vascular shunt surgery. Vascular bio-hybrids that have the properties of pristine vascular endothelium may be a key step forward in maintaining angio-access in patients who require haemodialysis.

Intraperitoneal administration of the angiogenesis inhibitor thalidomide does not impair anastomotic healing following large bowel resection in a rabbit model.

The effects of thalidomide after intraperitoneal instillation on the healing of colonic anastomoses are not known. A series of 40 New Zealand White rabbits underwent an end-to-end colonic anastomosis. The animals were randomized into four groups. Groups 1 (n = 10) and 2 (n = 10) were treated with dissolved thalidomide 200 mg/kg intraperitoneally, whereas groups 3 (n = 10) and 4 (n = 10) were treated only with the dissolver. Animals were sacrificed at day 3 (groups 1, 3) and day 7 (groups 2, 4). Anastomotic healing was tested by measuring the bursting pressure in vitro. Immunohistochemical staining of the anastomotic site was performed with polyclonal antibodies against CD31 and Mib-1, to determine a possible antiangiogenic or antiproliferative effect. Statistical analysis was performed using Spearman's log rank correlation and paired t-test. On postoperative day 3 (p > 0.19) and postoperative day 7 (p > 0.73), there was no difference in bursting pressure in the treatment and the control groups. Angiogenesis scores were reduced at day 3 in the thalidomide group (p < 0.05), but did not differ between the groups at day 7. White blood cell counts were decreased in the treatment groups at day 3 (p < 0.01) and day 7, compared to control groups (p < 0.01). There was no difference in the expression of Mib-1 in either group at day 3 or day 7. The intraperitoneal administration of thalidomide does not interfere with the healing of colonic anastomosis. Although the angiogenesis score is diminished at day 3, this did not lead to a reduced bursting pressure at day 3 or day 7.

Surgical treatment of fractures of the distal clavicle with polydioxanone suture tension band wiring: an alternative osteosynthesis.

Fracture of the distal clavicle type II (Neer) is an indication for surgical intervention. We report our experience in 12 patients with acute clavicular fractures and operative treatment with polydioxanone suture (PDS) tension band wiring. The patients were assessed 6 and 12 weeks postoperatively by radiological and clinical evaluation and with the Constant Murley score. All 12 patients had an excellent functional result 12 weeks postoperatively. The Constant Murley score was excellent in all patients. The PDS band can be considered as an alternative osteosynthesis. In the context of the current literature, the advantages and disadvantages of this new procedure are discussed.

Serum vascular endothelial growth factor levels correlate better with tumour stage in small cell lung cancer than albumin, neuron-specific enolase or lactate dehydrogenase.

OBJECTIVE: Vascular endothelial growth factor (VEGF) is an important cytokine in the process of angiogenesis. Elevated serum levels of the cytokine may determine cancer patients who will benefit from adjuvant anti-angiogenic therapy in the future. To correlate serum levels of VEGF with tumour stage and established prognostic markers in patients with small cell lung cancer (SCLC), a prospective study was performed on 70 patients. METHODOLOGY: From August 1999 to May 2000, 70 consecutive patients (51 male, 19 female) with histologically proven SCLC were enrolled into the study. Staging of the disease included clinical investigation, bronchoscopy, chest X-ray, thoracic computed tomography and ultrasound. The patients were grouped into five stages according to the Marburg classification (very limited disease (VLD), limited disease (LD), extensive disease I (EDI), extensive disease II (EDII) and extensive disease III (EDIII)). Prior to treatment, a 10 mL serum sample from each patient was examined by ELISA to quantify levels of VEGF and neuron-specific enolase (NSE). Lactate dehydrogenase (LDH) and albumin levels were determined by photomorphometric analysis. Statistical analysis was performed using the Waller-Duncan k ratio t-test and Pearson's correlation test. RESULTS: Serum VEGF levels correlated well with tumour stage (P < 0.0001). Albumin levels were not correlated with tumour stage, but levels of NSE and LDH increased with stage progression. When patients were divided into two groups (VLD and LD vs EDI-III), VEGF levels were significantly lower in the initial stages of the disease compared with extensive disease (P < 0.0001). Serum levels of VEGF correlated better with tumour stage than did concentrations of NSE, LDH or albumin. CONCLUSION: Serum VEGF levels may serve as an additional prognostic marker in the course of patients with SCLC. Further studies are needed to determine whether these patients may benefit from additional anti-angiogenic therapy in the future.

In vivo measurement of oxygen-derived free radicals during reperfusion injury.

By use of an optimized cytochrome c-based biosensor, superoxide radical production was measured continuously in vivo. The aim of this study was the online detection of superoxide concentration during reperfusion after a variable time of ischemia. Measurements were performed by placing the detecting sensor into gastrocnemius muscle tissue. Ischemia was induced by clamping the vena and arteria femoralis. Current response of the sensor was recorded continuously as an equivalent for superoxide concentration. Ischemia times varied from 5 to 120 minutes. The minimum ischemia time to record superoxide production was 10 minutes. By inducing longer periods of ischemia, an increase in superoxide concentration reached its highest levels at 2 hours. Furthermore, the total time of superoxide production after reperfusion depended on the total time of ischemia.

Thalidomide given intraperitoneally reduces the number of postoperative adhesions after large bowel resection in rabbits.

OBJECTIVE: To investigate the effect of thalidomide given intraperitoneally on the formation of adhesions after colonic resection in rabbits. DESIGN: Controlled, randomised prospective study. SETTING: University hospital, Germany. ANIMALS: 40 female New Zealand White rabbits. INTERVENTIONS: After an end-to-end colonic anastomosis the animals were given thalidomide 200 mg/kg in 1% carboxymethylcellulose intraperitoneally or carboxymethylcellulose alone (n = 20 in each group). OUTCOME MEASURES: The adhesion score according to Tyrell on day 3 (n = 20) and day 7 (n = 20) postoperatively, weight, behaviour, and white cell count (WCC). RESULTS: There was no difference in behaviour or weight. On the third postoperative day WCCs and on the seventh postoperative day WCCs and adhesion scores, were lower in the thalidomide group (p < 0.01). CONCLUSION: The number of postoperative adhesions was reduced in the group given thalidomide intraperitoneally. Our results suggest that thalidomide may be helpful in the prevention of postoperative adhesions.