the isolated finding of a retroperitoneal mass ( rm ) often represents a diagnostic challenge . even when possible , an image - guided biopsy frequently provides an inadequate specimen for diagnostic purposes . open retroperitoneal exploration is often the only option capable of obtaining sufficient tissue for diagnosis ; however , this necessitates a major operation . with increasing experience in laparoscopic retroperitoneal surgery , the use of laparoscopy for exploration of an indeterminate retroperitoneal mass may provide a minimally invasive alternative to open exploration . herein , we report our experience with four laparoscopic explorations for rm and compare our results with four contemporary open explorations for rm . from july 1995 to january 1998 , four consecutive patients , aged 50 to 62 years old , with computed tomo - graphic findings of a retroperitoneal mass underwent laparoscopic exploration by one surgeon ( rvc ) . preoperative evaluation included computed tomography of the abdomen and chest radiography . in each case , the only finding was a retroperitoneal mass ( figure 1 ) . in the laparoscopic group , all patients had either preoperative biopsy of the mass or a biopsy of an enlarged peripheral lymph node . a , b. preoperative ct of patient # 3 showing a 4 cm left retroperitoneal mass located posterior to the renal hilum and lateral to the aorta ; renal vessels are displaced anterior . for laparoscopic exploration , all patients underwent placement of a ureteral stent and foley catheter . a pneumoperitoneum was created with a veress needle inserted 3 cm above and medial to the anterior superior iliac spine ; a 12 mm port was placed . additional 12 mm ports were placed in the mid - clavicular line subcostally and just above and lateral to the umbilicus . another 5 mm port was placed in the posterior axillary line subcostally for placement of a 5 mm retractor . the colonic mesentery was further separated from gerota 's fascia ; the mass was identified and either an incisional or excisional biopsy was done . in patients undergoing open exploration , blood loss was assessed by the anesthetist 's estimation and by comparing preoperative and postoperative hematocrit . also , we recorded the complications , time to ambulation , time for resumption of a regular diet , analgesic use , the hospital stay and the hospital charges . a definitive diagnosis was obtained for all patients after the exploration either by incisional or excisional biopsy ( figure 1 , 2 ) . the age , sex , past medical history and preoperative investigation results are summarized in table 1 . preoperative biopsy was performed in six patients ; only two findings correlated with the final pathologic report . of note , the tumors were smaller in the laparoscopic group ( 3 of 4 < 5 cm ) while two of the four lesions in the open group were 10 cm ( table 1 ) . a , b. four - months post - laparoscopic excisional biopsy in patient # 3 showing area of resected mass , no recurrences , surgical clips lateral to aorta . postoperative complications were observed in one of the laparoscopic explorations and in three of the open explorations . the only complication in the laparoscopic group was a major complication : proximal , small bowel obstruction due to incarceration of bowel into a 12 mm port site . this occurred despite closing the fascia of the 12 mm incisions with a single 1 - 0 absorbable suture . the patient underwent laparoscopic reduction and repair of the hernia on postoperative day 4 . in the open group , there was one major complication ( urine extravasation ) , as well as two minor complications ( a urinary tract infection and a subcutaneous hematoma ) . the blood loss ( 90 vs 440 ml ) , hematocrit drop ( 5.1 vs 7.8 % ) , time to resumption of regular diet ( 3 vs 5 days ) , amount of morphine sulfate equivalents required ( 128 mg vs 161 mg ) , time to ambulation ( 2.3 vs 6 days ) and hospital stay ( 4.8 vs 6 days ) were each less in the laparoscopy patients ( table 3 ) . the operation time was longer for the laparoscopic procedure ( 7.8 vs 4.3 hours ) ; the laparoscopic time included the time to place the ureteral stent and to reposition the patient . due to the prolonged operation time , the laparoscopic procedure was about $ 5000 more costly than the open approach ( table 3 ) . total operation time included the time for preliminary procedure , eg , cystoscopy , ureteral stent placement and patient repositioning . one patient had controlled epidural anesthesia and was thus excluded from the open data group . the laparoscopic data include one patient with postoperative incarcerated incisional hernia with laparoscopic reduction and repair of hernia with a hospital stay of 10 days . retroperitoneal tumors may either arise from solid organs ( eg , kidney , pancreas and adrenal ) or from non - specific tissues that traverse the retroperitoneal space ( eg , lymphatic tissue , muscle , nerve , fat and connective tissue ) . these lesions may be benign , malignant or inflammatory in nature ( table 4 ) . computed tomography ( ct ) and magnetic resonance imaging ( mri ) can provide information on the location , anatomy and extent of the mass , but are otherwise largely nondiagnostic . indeed , in all instances , the determination of appropriate therapy depends upon obtaining an adequate tissue sample for histologic diagnosis . in this respect , image - guided percutaneous biopsy can be used , but it suffers from a low diagnostic yield due to the small amount of tissue obtained and because an inflammatory infiltrate may have an appearance similar to a malignancy . indeed , preoperative image - guided biopsies were either incorrect or inadequate in four of our six cases . accordingly , surgical exploration with adequate tissue sampling is frequently necessary to establish a definitive diagnosis . for some malignant and benign tumors of the retroperitoneum , an excisional biopsy may be both diagnostic and curative . laparoscopic exploration potentially can provide a minimally invasive means to obtain adequate tissue for histologic diagnosis without the need for a major midline abdominal or flank incision . all of our patients who underwent laparoscopic exploration tolerated the procedure well and were able to ambulate and resume a full diet within five days . the postoperative pain was minimal , and the hospital stay was brief ( average 4.8 days ) . in the laparoscopic cases , two patients had an excisional biopsy , and two patients had an incisional biopsy . in all four cases , a definitive diagnosis was made , and no further surgical intervention was necessary . in comparison with open exploration , the laparoscopic approach was equally as effective , yielding a definitive diagnosis in all four cases . however , due to longer operative time , the laparoscopic procedure was more costly and , hence , less efficient than the open approach . with regard to morbidity , patient recovery and hospital stay , in summary , we believe that laparoscopic exploration for a retroperitoneal mass of undetermined origin is a viable alternative to open exploration . the laparoscopic approach is as effective , albeit less efficient , than an open procedure ; however , the laparoscopic approach provided benefits with regard to patient morbidity and convalescence . as urologic surgeons become more experienced with laparoscopic techniques and with the advent of more efficient nondisposable instrumentation , we anticipate that the operative time and cost for more complex laparoscopic procedures , such as retroperitoneal exploration , will decrease . nonetheless , our initial experience with laparoscopic retroperitoneal exploration is favorable , and we are now offering this approach as first - line therapy in these patients .
background and objectives : the isolated finding of a retroperitoneal mass ( rm ) often represents a diagnostic challenge . 
 image - guided biopsy is frequently inadequate for diagnosis . with increasing experience , the use of laparoscopy for 
 exploration of an indeterminate rm may provide a minimally invasive alternative to open exploration . herein , we present a retrospective review of our initial four laparoscopic explorations , comparing our experience to four contemporary open explorations for an rm.patients and methods : from july 1995 to january 1998 , four patients , aged 50 to 62 years old , with an rm of undetermined etiology underwent laparoscopic exploration . 
 another four patients underwent open exploration at the same hospital . 
 the medical records of these patients were reviewed.results:the tumors were smaller in the laparoscopic group , averaging 3.7 cm ( range 2 - 6 cm ) vs 6.5 cm ( range 1 - 10 cm ) in the open group . 
 a definitive diagnosis was obtained for all eight patients . 
 postoperative complications were observed in one of the laparoscopic explorations , and in three of the open explorations ; there was no operative mortality . 
 the blood loss ( 90 vs 440 ml ) , fall in hematocrit ( 5.1 vs 7.8% ) , time to resumption of a regular diet ( 3 vs 5 days ) , amount of morphine sulfate equivalents required for analgesia ( 128 mg vs 161 mg ) , time to ambulation ( 2.3 vs 6 days ) and hospital stay ( 4.8 vs 6 days ) were all less among the laparoscopy patients . 
 however , the operative time was longer for the laparoscopic procedure ; this time included stent placement and patient repositioning in addition to the time for laparoscopic excision of the mass ( 7.8 vs 4.3 hours).conclusion : laparoscopic exploration appears to be a viable alternative to open exploration in patients presenting with a retroperitoneal mass . 
 it is as effective as an open procedure and provides benefits with regard to patient morbidity and convalescence . 
 however , operative time for this laparoscopic procedure is lengthy .