Incidence and management of pleural effusions after diaphragm peritonectomy or resection for advanced mullerian cancer

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1 Gynecologic Oncology 103 (2006) Incidence and management of pleural effusions after diaphragm peritonectomy or resection for advanced mullerian cancer Eric L. Eisenhauer a, Michael I. D'Angelica b, Nadeem R. Abu-Rustum a, Yukio Sonoda a, William R. Jarnagin b, Richard R. Barakat a, Dennis S. Chi a, a Gynecology Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, MRI-1026, New York, NY 10021, USA b Hepatobiliary Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA Received 2 March 2006 Available online 3 July 2006 Abstract Objectives. Diaphragm peritonectomy or resection is an effective way to cytoreduce diaphragm disease but frequently results in sympathetic pleural effusions. Our objective was to determine the incidence and management of effusions that developed after diaphragm surgery in patients with advanced mullerian cancer. Methods. We reviewed the records of all patients with stage IIIC IV epithelial ovarian, fallopian tube, or peritoneal cancer who had diaphragm peritonectomy or resection as part of optimal primary cytoreduction at our institution from All patients had preoperative and serial postoperative chest X-rays to detect and follow pleural effusions. Factors evaluated included the presence and size of preoperative and postoperative effusions, their laterality, and subsequent need for thoracentesis and/or chest tube placement for symptomatic effusions. Results. Of the 215 patients who had primary cytoreduction during the study period, 59 (27%) underwent diaphragm peritonectomy or resection. In addition to standard cytoreduction, 31 (53%) of these 59 patients had diaphragm surgery alone, while 28 (47%) had diaphragm surgery in combination with other upper abdominal resections. Laterality of diaphragm surgery was as follows: right only, 43 (73%); left only, 2 (3%); and bilateral, 14 (24%). Intraoperative chest tubes were placed in 7 (12%) patients. In the remaining 12 patients with preoperative effusions, postoperative effusions on the same side as the diaphragm surgery increased in 6 patients (50%), and 3 patients (25%) required postoperative thoracentesis or chest tube. In the remaining 40 patients without preoperative effusions, ipsilateral effusions developed in 24 patients (60%), and 5 patients (13%) required postoperative chest tubes. The overall rate of new or increased ipsilateral effusions was 58%; the overall rate of postoperative thoracentesis or chest tube placement was 15%. In 75% of the patients, thoracentesis or chest tubes were placed within 5 days of surgery (median, 3 days; range, 2 24). Conclusions. More than half of patients developed ipsilateral pleural effusions after diaphragm peritonectomy for cytoreduction. Most were managed conservatively without requiring a chest tube or thoracentesis. The incidence of symptomatic effusions was not high enough to recommend routine chest tube placement at the time of diaphragm peritonectomy or resection Elsevier Inc. All rights reserved. Keywords: Ovarian cancer; Cytoreduction; Diaphragm surgery; leural effusion Introduction Cytoreductive surgery is the mainstay of initial therapy for epithelial ovarian cancer, and the extent of this cytoreduction is resented at the Thirty-Seventh Annual Meeting of the Society of Gynecologic Oncologists; alm Springs, CA; March 22 26, Corresponding author. Fax: address: gynbreast@mskcc.org (D.S. Chi). the most consistently reported prognostic factor for subsequent patient survival [1,2]. In addition to patients with bulky pelvic or omental disease, this improved survival has also been seen in patients with biologically aggressive tumors [3]. Extensive procedures have been increasingly reported as a means by which to extend the benefits of surgical cytoreduction to patients who present with large-volume disease in the upper abdomen [4]. At initial surgical exploration, large-volume diaphragmatic disease may be the largest metastatic site, and has been /$ - see front matter 2006 Elsevier Inc. All rights reserved. doi: /j.ygyno

2 872 E.L. Eisenhauer et al. / Gynecologic Oncology 103 (2006) identified as one of the most common factors precluding optimal cytoreduction [5,6]. In a series of 163 patients with stage III or IVovarian cancer, diaphragm peritonectomy (D) or diaphragm resection (DR) was required in 40.5% of the patients in order to render 98% of the patients with residual disease less than 1 cm [3]. revious reports have described the technique and safety of both stripping away the involved peritoneum and resecting implants that invade into or through the muscle of the diaphragm [7,8]. Since 2000, we have increasingly applied these techniques in our comprehensive approach to primary surgical cytoreduction, with a low rate of complications and an attendant increase in our rate of optimal cytoreduction [9]. revious series have reported the morbidity associated with diaphragm surgery with varying degrees of detail, and the overall number of reported major complications is low [7,8,10 13]. We have found that patients undergoing diaphragm surgery often develop postoperative pleural effusions, but infrequently require pleural drainage by thoracentesis or chest tube. This study was conducted to more clearly define the incidence of postoperative pleural effusions, the incidence of subsequent pleural drainage, and the patient, tumor, or surgical factors associated with these events. Methods After obtaining Institutional Review Board approval, the prospectively maintained Virginia K. ierce Gynecology Service Database was used to identify all patients who underwent primary cytoreductive surgery for ovarian, fallopian tube, or primary peritoneal cancer at our institution between January 1, 2000 and December 31, Exclusion criteria included non-epithelial histology, prior surgical exploration at another institution, neoadjuvant chemotherapy, and stage IABIIIB cancers. The records of all patients with stage IIIC and IV epithelial ovarian cancers undergoing primary surgical exploration were then reviewed to identify those patients who had D and/or DR as part of their surgical procedure. atients undergoing ablative procedures, such as Cavitron ultrasonic aspiration (CUSA) or argon beam coagulation (ABC), for diaphragmatic disease were not included. All patients with medical comorbidities had preoperative medical clearance, and no patients who underwent these procedures had severe cardiopulmonary disease. Individual records for all patients were reviewed, and the following preoperative information was collected: age at surgery, date of surgery, primary site of disease, American Society of Anesthesiologists (ASA) class, and presence and side of preoperative pleural effusion. reoperative lab s recorded included serum levels of CA-125, hemoglobin, platelets, albumin, total protein, prothrombin time, and aspartate aminotransferase (AST). Intraoperative information collected included presence and volume of ascites, surgical procedures performed, diameter of largest residual tumor nodule, duration of surgery, estimated blood loss (EBL), and number of units of blood transfused intraoperatively. Details of the diaphragm surgery recorded were side of stripping or resection, extent of resection, whether full liver mobilization was performed, and whether diaphragm perforation occurred intraoperatively. athologic information collected included histologic type, tumor grade, and dimensions of the diaphragm specimen removed. ostoperative information recorded included presence and side of pleural effusions, date of diagnosis of effusions, need for drainage by thoracentesis or chest tube, timing of drainage, if necessary, and length of hospital stay. All patients were staged according to the International Federation of Gynecology and Obstetrics (FIGO) system. Optimal cytoreduction was defined as no residual tumor nodule measuring greater than 1 cm in largest dimension at the completion of surgery. D was defined as peritonectomy performed by dissection of the overlying peritoneum from the underlying diaphragm muscle. DR was defined as a full-thickness resection of diaphragm muscle and overlying peritoneum. Limited vs. extensive D was defined by whether the specimen removed was less than or greater than the median surface area for the cohort. All DRs were considered extensive. atients categorized as having liver mobilization had full dissection of the coronary and triangular ligaments on the appropriate side, as well as the falciform ligament. atients who had dissection of the falciform ligament alone were not included as having had liver mobilization. All patients were followed with serial chest radiography postoperatively. All radiographs were read by an attending radiologist and the presence of pleural effusions identified from the final report. leural effusions were defined as the radiographic presence of fluid extending into at least the lower third of the lung field. In this study, blunting of the costophrenic angle alone was not included as diagnostic of an effusion. s were defined as effusions on the same side as the diaphragm surgery. In patients with bilateral diaphragm peritonectomy or resection, a pleural effusion on either side was included as an ipsilateral effusion. In patients with preoperative effusions not drained intraoperatively, an increase in the size of the effusion was included as a positive finding. atients were evaluated as to whether or not they developed an ipsilateral postoperative effusion, and statistical tests were performed as appropriate for the data distribution. Categorical variables were evaluated by χ 2 analysis or Fisher's exact test as appropriate for category size. Continuous variables were evaluated by Student's t test or Wilcoxon Mann Whitney test for normal and non-normal distributed data, respectively. Logistic regression was performed to determine factors independently associated with developing a postoperative pleural effusion. s with < 0.10 in the univariate analysis were included in the multivariate model. Because the odds ratio produced by logistic regression will overestimate risk when the outcome is common (58% in our cohort) [14], relative risk estimation was performed by oisson regression with robust error variance [15]. Acceptability of the multivariate model was determined by the Hosmer Lemeshow goodness-of-fit test. All statistical tests were two-sided and differences were considered statistically significant at < Data analysis was performed with Stata statistical software (version 8.2, StataCorp L, College Station, TX). Results During the study period, 215 patients underwent primary cytoreductive surgery for stage IIIC or IV at our institution. Of these 215 patients, 59 (27%) had D/DR as part of their surgical procedure. All 59 patients were optimally cytoreduced at the completion of surgery. The median age of the cohort was 66 years (range, 41 81). Most patients had ovarian cancer (88%), stage IIIC disease (75%), serous histology (90%), and ascites present at surgery (93%). leural effusions were present in 16 patients (27%) preoperatively right-sided, 7; left-sided, 6; and bilateral, 3. Chest tubes were placed intraoperatively in 7 patients (12%). Because intraoperative chest tube placement obscured the ability to determine whether a postoperative effusion developed, these patients were excluded from subsequent analysis, and are described later. In the remaining 52 patients, ipsilateral postoperative pleural effusions developed in 30 (58%). Subsequent comparison was performed between patients who did or did not develop an ipsilateral postoperative effusion. There were no significant differences between the two groups in age at surgery, primary disease site, tumor stage, tumor grade, histologic type, ASA class, and presence of a preoperative effusion (Table 1). When preoperative laboratory s were examined as continuous variables, patients who developed ipsilateral effusions had a lower mean serum albumin ( = 0.05) and total protein ( = 0.03; Table 2). When these same laboratory s were examined as categorical

3 E.L. Eisenhauer et al. / Gynecologic Oncology 103 (2006) Table 1 atient characteristics and tumor features Table 2 reoperative laboratory s Age (years) Median Range Site Ovary 20 (90%) 26 (87%) 0.82 Fallopian 1 (5%) 1 (3%) tube eritoneum 1 (5%) 3 (10%) Stage of disease IIIC 17 (77%) 24 (80%) 0.81 IV 5 (23%) 6 (20%) Tumor grade 1 2 (9%) 0 (0%) (18%) 2 (7%) 3 15 (68%) 27 (90%) None 1 (5%) 1 (3%) Histologic type Serous 22 (100%) 26 (87%) 0.13 Mixed 0 (0%) 4 (13%) ASA class I 3 (14%) 1 (3%) 0.26 II 10 (45%) 18 (60%) III 8 (36%) 7 (23%) reop pleural effusion Right 3 (14%) 1 (3%) 0.61 Left 2 (9%) 3 (10%) Bilateral 1 (5%) 2 (7%) Any 6 (27%) 6 (20%) 0.74 ASA, American Society of Anesthesiologists. CA-125 (U/mL) Median Range > (64%) 23 (77%) 0.31 latelets (K/mcL) Median (range) 376 ( ) 472 ( ) 0.27 >400 7 (32%) 19 (63%) 0.04 Hemoglobin (g/dl) Mean 12.3± ± < (23%) 7 (23%) 1.00 Albumin (g/dl) Mean 4.1± ± <4.0 6 (27%) 17 (57%) 0.04 Total protein (g/dl) Mean 7.0± ± <6.3 2 (9%) 8 (27%) 0.16 rothrombin time (s) Mean 13.4± ± > (18%) 3 (10%) 0.43 AST (U/L) Median (range) 24 (15 44) 26 (13 79) 0.19 >37 2 (9%) 5 (17%) 0.68 AST, aspartate aminotransferase. variables using our laboratory cutoff for abnormal s, patients who developed an ipsilateral effusion were more likely to have a preoperative platelet count >400 K/mcL ( = 0.04) and a serum albumin <4.0 g/dl ( = 0.04). Most patients had multiple cytoreductive procedures performed (Table 3). The two groups showed no statistically significant differences in any of the standard or extensive surgeries performed. atients had multiple extensive procedures performed at similar rates in the two groups. Differences were apparent in the details of the diaphragm surgery performed (Table 4). atients who developed ipsilateral effusions were more likely to have had liver mobilization performed (93% vs. 59%, = 0.005), and had a larger median specimen diameter (9 vs. 5 cm, = 0.03) and surface area (60 vs. 30 cm 2, = 0.04). The majority of patients had peritonectomy or resection of the right diaphragm (96%). Neither diaphragm resection nor diaphragm perforation was associated with a significantly increased rate of ipsilateral effusion. Intraoperative and postoperative variables were similar in the two patient groups (Table 5). Ascites was present in the majority of patients in both groups, with a similar large median volume (3000 vs ml). Duration of surgery, EBL, and quantity of blood transfused were similar. Complete cytoreduction was achieved in 12 patients (23%). Largest remaining tumor diameter was similar in the two groups. leural effusions were most commonly diagnosed on the second postoperative day. Of the patients who developed effusions, 27 (90%) had their effusion diagnosed in the first 6 postoperative days. An ipsilateral pleural effusion was not associated with an increased length of hospital stay. Several factors were significantly associated with a postoperative ipsilateral effusion by univariate analysis platelet count >400 K/mcL, albumin <4.0 g/dl, total protein <6.3 g/dl, Table 3 rocedures performed Standard procedures TAH±USO/BSO 22 (100%) 29 (97%) Omentectomy 21 (95%) 24 (80%) 0.22 elvic LND 9 (41%) 12 (40%) 1.00 ara-aortic LND 9 (41%) 12 (40%) 1.00 Large bowel resection 9 (41%) 16 (53%) 0.38 Small bowel resection 1 (5%) 2 (7%) 1.00 Extensive procedures D/DR 22 (100%) 30 (100%) D/DR only 12 (55%) 18 (60%) 0.69 Splenectomy 3 (14%) 7 (23%) 0.49 Distal pancreatectomy 2 (9%) 3 (10%) 1.00 Liver resection 4 (18%) 4 (13%) 0.71 orta hepatis resection 3 (14%) 6 (20%) 0.72 Cholecystectomy 3 (14%) 4 (13%) 1.00 VATS 0 (0%) 1 (3%) 1.00 TAH, total abdominal hysterectomy. USO/BSO, unilateral/bilateral salpingo-oophorectomy. LND, lymph node dissection. D/DR, diaphragm peritonectomy/diaphragm resection. VATS, video-assisted thoracoscopic surgery.

4 874 E.L. Eisenhauer et al. / Gynecologic Oncology 103 (2006) Table 4 Diaphragm surgery and whether full liver mobilization was performed (Table 6). reoperative pleural effusion, large-volume ascites, bilateral diaphragm surgery, diaphragm perforation, and additional upper abdominal procedures were not predictive. On multivariate analysis, only liver mobilization remained independently associated with developing a postoperative ipsilateral effusion (relative risk [RR], 3.76; 95% CI, ; = 0.04). A total of 15 patients had pleural drainage performed by either thoracentesis or chest tube. Seven patients had chest tubes Table 5 Intraoperative findings and postoperative course D/DR Right 18 (82%) 18 (60%) 0.34 Left 0 (0%) 2 (7%) Bilateral 4 (18%) 10 (33%) Extent of D/DR Limited 14 (64%) 12 (40%) 0.09 Extensive 8 (36%) 18 (60%) Specimen diameter (cm) Median Range Specimen surface area (cm 2 ) Median Range Liver mobilization 13 (59%) 28 (93%) DR 1 (5%) 3 (10%) 0.63 Diaphragm perforated 3 (14%) 8 (27%) 0.22 D/DR, diaphragm peritonectomy/diaphragm resection. Ascites present 20 (91%) 28 (93%) 1.00 Ascites volume (ml) Median Range ,000 Duration of surgery (min) Median Range Estimated blood loss (ml) Median Range Intraop RBC (units) Median Range Residual disease No visible 6 (27%) 6 (20%) 0.67 <0.5 cm 11 (50%) 14 (47%) cm 5 (23%) 10 (33%) Hospital stay (days) Median Range ostop day of diagnosis Median 2 Range 0 31 RBC, packed red blood cells. placed intraoperatively for the following reasons: diaphragm resection, 3, diaphragm perforation, 2, and video-assisted thoracoscopic surgery (VATS), 2. Approximately one third of patients undergoing DR (3/8, 38%) and one half of patients undergoing VATS (2/4, 50%) had chest tubes placed intraoperatively. The majority of recognized diaphragm perforations, either from diaphragm resection or perforation during dissection, were managed without chest tube placement. These patients had a catheter placed in the diaphragmatic defect that was closed with a pursestring suture under waterseal after the pleural air had been evacuated. All DRs in this series were closed primarily without mesh or graft. ostoperative pleural drainage was performed in 8 patients (15%). The laterality of thoracentesis or chest tube was as follows: right 5, left 2, and bilateral, 1. Symptomatic pleural effusion was the most common reason for drainage (7/8, 87%), with 1 additional patient requiring chest tube placement for pneumothorax. leural drainage was performed at a median of 3 days postoperatively (range 2 26 days), with 6 (75%) of the 8 patients requiring drainage within the first 5 postoperative days. There were no patients who developed respiratory distress requiring ventilatory support and no cases of resultant pneumonia. Chest tubes placed intraoperatively remained in place a median of 8 days (range, 3 12 days), while chest tubes placed postoperatively were kept in place a median of 5 days (range, 2 11 days). The duration of chest tube drainage was equivalent whether placed intraoperatively or postoperatively ( = 0.39). Similarly, patients with chest Table 6 Logistic regression model for risk of ipsilateral pleural effusion after diaphragm peritonectomy or resection Risk ratio 95% CI Univariate Multivariate atient characteristics Age 1.01/yr Stage, IV vs. IIIC ASA, 3 vs. 1 or reop pleural effusion Ascites > 2000 ml latelets > 400 K/mcL Hemoglobin < 11.5 g/dl Albumin < 4.0 g/dl Total protein < 6.3 g/dl Intraoperative procedures D/DR, bilateral vs. unilateral D/DR, extensive vs. limited Liver mobilization Diaphragm perforation D/DR+any other extensive Operative Factors Duration of surgery > 330 min EBL > 1000 ml ASA, American Society of Anesthesiologists. D/DR, diaphragm peritonectomy/diaphragm resection. EBL, estimated blood loss. Multivariate Hosmer Lemeshow goodness-of-fit χ 2 = 6.5, = 0.59.

5 E.L. Eisenhauer et al. / Gynecologic Oncology 103 (2006) tubes placed intraoperatively had a median length of hospital stay (LOS) of 11 days (range, 5 32 days) compared with a median LOS of 11 days (range, 6 44 days) for patients who required postoperative chest tube drainage ( = 0.87). There was no difference in LOS between those patients who required chest tube drainage and those who did not (median, 11 vs. 10 days; = 0.39). All variables previously examined were re-analyzed within the subgroup that had an ipsilateral effusion to compare those patients who did or did not require pleural drainage. No factors were found to be predictive of which patients who developed ipsilateral effusions subsequently required thoracentesis or chest tube. Only bilateral (vs. unilateral) D/DR approached statistical significance (RR, 3.3; 95% CI, ; = 0.06). All patients requiring pleural drainage had undergone full liver mobilization; Twenty (91%) of 22 patients who developed effusions but did not require postoperative drainage, had had liver mobilization. Discussion Surgical cytoreduction remains the most accepted initial treatment of advanced stage epithelial ovarian cancer, with the amount of residual tumor setting the stage for future prognosis and response to adjuvant therapy [1,2,16]. Large diaphragmatic metastases have been cited as a significant barrier to optimal cytoreduction by as many as 76% of the members of the Society of Gynecologic Oncologists surveyed [6]. Increasingly, published reports have shown the feasibility of resecting diaphragmatic disease, with a low risk of major complications [7 13]. We found it worthwhile to explore a commonly observed postoperative event in these patients-postoperative pleural effusions. As D and DR become more frequently employed, it is useful to better understand the incidence, risk factors, and potential mechanism for their occurrence. Recognized risk factors for postoperative complications, such as EBL and duration of surgery, did not predict the development of postoperative effusions in these patients. In order to determine the extent to which systemic factors played a role in the development of these effusions, we performed a thorough comparison of preoperative laboratory s. Although the proportion of patients with thrombocytosis, hypoalbuminemia, and hypoproteinemia differed between the two groups, these s were not predictive on multivariate analysis. Similarly, the extent of D/DR, bilateral diaphragm surgery, and additional upper abdominal procedures were not predictive of which patients subsequently developed effusions. The majority of published reports on diaphragm surgery focus on full thickness diaphragm resection. Although these studies differ in the detail with which complications are reported, the overall incidence of major complications reported has been low. Initial series were predominantly directed toward feasibility and technique, and reported a low incidence of complications related to hemorrhage or pneumothorax [7,10 12]. A larger series of 41 patients who had diaphragm resections performed primarily for recurrent disease was reported from the Mayo Clinic [8]. In the 31 patients who did not have intraoperative chest tube placement, 3 (10%) subsequently required chest tube placement and 5 (16%) required thoracentesis for symptomatic pleural effusions. The authors suggested the possibility that extensive procedures in the right upper quadrant contribute to the development of postoperative pleural effusions. Montz and colleagues described their technique and experience in 11 of 14 patients undergoing D for cytoreduction (7). Complications in this group included one postresection pneumothorax that resolved without drainage. Incidence of pleural effusions was not reported, but presumably there were no cases requiring pleural drainage. Kuhn and associates reported their complications in a series of patients with stage III or IV ovarian cancer undergoing extensive upper abdominal cytoreduction and/or bowel resection vs. standard cytoreduction [17]. In patients requiring more extensive surgery, 26 (63%) of 41 patients developed postoperative pleural effusions, compared to 19/66 (29%) who underwent standard surgery ( < 0.001). Within the subgroup undergoing more extensive procedures, there was a similar rate of pleural effusions whether patients had diaphragm peritonectomy alone (11/18, 61%) or other abdominal resections with or without D (15/23, 65%). Although the incidence of preoperative effusions, the extent of liver mobilization, and frequency that pleural drainage was required for these effusions was not reported, the overall incidence of ipsilateral pleural effusions in our series was comparable (30/52. 58%). Similarly, we found no increased incidence of ipsilateral effusions when additional upper abdominal procedures were performed in conjunction with D/DR. Fluid that accumulates in the pleural space in patients with ascites generally results from a peritoneal-to-pleural transfer rather than as a primary thoracic process. In 1943, Meigs and colleagues described the transfer of India ink via the lymphatic system into the thoracic cavity in patients with ascites and hydrothorax associated with ovarian fibromas [18]. Subsequent evidence from the hepatic literature, both pathologic [19,20] and thoracoscopic [21], has shown that anatomic defects in the diaphragm are more likely the cause in patients with ascites from primary hepatic disease. Diaphragmatic defects in conjunction with ascites appear to cause fluid from the peritoneal cavity to be drawn up by negative intrathoracic pressure, forming pleural blebs that may break and cause direct communication with the pleural space. The occurrence of sympathetic effusions after liver mobilization appears to follow this process and may give some clues to its pathogenesis. Complete dissection of the hepatic ligaments and exposure of the diaphragmatic bare area is significantly associated with an increased rate of pleural effusions, while ameliorating the effect of negative thoracic pressure by mechanical ventilation for at least 18 h postoperatively is associated with a subsequently decreased effusion rate [22]. Fibrin deposits tend to close the surgical defect within the first few days after surgery, and fibrin sealant sprayed intraoperatively on the dissected areas was associated with a

6 876 E.L. Eisenhauer et al. / Gynecologic Oncology 103 (2006) decreased effusion rate [23]. Recently, a randomized trial using the ABC to seal the cut hepatic ligaments and bare area of the retroperitoneum in patients undergoing hepatectomy showed a similar decrease [24]. leural effusions were reduced from 28% (9/32) to 4% (1/28) in the group randomized to ABC of the ligaments and bare area; the number of patients requiring pleural drainage was decreased from 19% (6/32) to none (0/28) in the group in which the ABC was applied. While the rate of pleural effusions in patients undergoing hepatectomy with liver mobilization is generally reported in the 28 33% range [23,24], we observed an ipsilateral effusion rate of 58% after D/DR. This may result from the larger portion of diaphragm left uncovered by peritoneum after D/ DR than is seen when the liver is mobilized for hepatectomy. Unrecognized disruption of the diaphragmatic muscle or underlying pleura in the process of D/DR may contribute to small defects that later connect to the pleural space. Recognized perforations were closed under waterseal after evacuation of air from the pleural space, which may explain why recognized diaphragm perforation was not a significant risk factor for ipsilateral effusion in this series. In addition, large-volume ascites was seen in a larger proportion of our patients undergoing D/DR than is commonly reported in patients undergoing hepatectomy. Finally, release of VEGF or inflammatory mediators by resection of tumor or direct surgery on the diaphragm may contribute but have not been specifically described. In the subgroup of patients who developed ipsilateral effusions, none of the factors examined was predictive of which patients subsequently required pleural drainage. Only bilateral diaphragm surgery approached statistical significance; this may be due to the fact the chance of developing an ipsilateral effusion in these patients was doubled. The rate of postoperative drainage was 15% (8/52) for all patients undergoing D/DR and 20% (8/41) in patients who had liver mobilization. At our institution, we do not feel that this rate is high enough to justify prophylactic intraoperative chest tube placement in all patients undergoing diaphragm surgery. Given the rate of symptomatic effusions, we choose to follow these patients with close attention to symptoms and serial postoperative imaging. Rapid access to necessary therapeutic procedures, however, must be available to follow these patients in this manner. The decision to drain postoperative effusions, as well as the method of drainage, was made in all cases at the discretion of the attending surgeon. Generally, drainage was performed when patients with known large effusions showed signs of respiratory compromise. Using these guidelines, there were no patients that required reintubation or subsequent ICU admission for respiratory distress. Ipsilateral pleural effusion occurred in 58% of our patients undergoing D/DR and occurred more frequently in patients who required liver mobilization by dissecting the coronary and triangular hepatic ligaments. Laterality of diaphragm surgery did not appear predictive, but the majority of patients had surgery on the right hemidiaphragm. The likely mechanism for these effusions is trans-diaphragmatic transfer of fluid from the peritoneal to pleural space before the peritoneal defect has closed. Applying the ABC to the exposed diaphragm surface after D/DR may decrease the incidence of postoperative pleural effusions, but has not yet been investigated in patients with advanced ovarian cancer. References [1] Randall TC, Rubin SC. 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