Efficacy of birth ball exercises on labour pain management.

OBJECTIVES: To evaluate the efficacy of a birth ball exercise programme conducted by physiotherapists on pain relief, psychological care, and facilitation of the labour process at a labour ward in a regional hospital. DESIGN: Case series with before-after comparisons. SETTING: Kwong Wah Hospital, Hong Kong. PARTICIPANTS: Chinese women admitted to the labour ward for spontaneous vaginal delivery between April and August 2012 were recruited. Physiotherapists taught birth ball exercises in groups or individually for 30 minutes. Labour pain intensity, back pain intensity, frequency of labour pain, stress and anxiety levels, and subjective pressure level over the lower abdomen were captured before and after birth ball exercises. Most of the parameters were measured using self-reported visual analogue scales. After the exercise session, physiotherapists measured the women's satisfaction level. Midwives recorded pethidine usage. RESULTS: A total of 203 pregnant women participated in this programme; 181 were in the latent phase group, whereas 22 were categorised into the no-labour-pain group. In both groups, there were statistically and clinically significant differences in back pain level, stress and anxiety levels, as well as pressure level over the lower abdomen before and after the exercise (P<0.05). In the latent phase group, significant decreases in labour pain and frequency of labour pain were demonstrated. Mean satisfaction scores were high, with visual analogue scale scores higher than 8.2 in both groups. Pethidine usage showed a further decreasing trend (6.4%) compared with the past 2 years. CONCLUSION: Birth ball exercise could be an alternative means of relieving back pain and labour pain in the labour ward, and could decrease pethidine consumption in labouring women.

Antenatally diagnosed cloacal exstrophy variant with intravesical phallus in a twin pregnancy.

We report a rare case of covered cloacal exstrophy variant with a hemiphallus trapped within partially closed bladder halves. The persistence of the cloacal membrane until at least 18 weeks' gestation, confirmed by antenatal ultrasound scanning, is discordant with existing theories of embryogenesis of cloacal exstrophy. The clinical presentation highlights the need for careful assessment, before and during surgery, to obtain a complete understanding of the anatomic defect before gender assignment and appropriate reconstructive efforts. A multispecialty approach and antenatal counseling are important, especially when only one fetus of twins has major birth defects.

Laparoscopic extravesicular ureteral reimplantation for vesicoureteral reflux: recent technical advances.

Ureteral reimplantation is an effective treatment for primary vesicoureteral reflux. Recent efforts have been directed toward reducing the perioperative morbidity of open reimplantation. We have refined the technique of laparoscopic extravesical ureteral reimplantation with emphasis on minimal tissue dissection, achieving reliable detrusor closure, and downsizing ports and instruments. With our current technique, excellent results comparable to those of established open procedures are achieved, while postoperative discomfort and the recovery period are significantly reduced. The laparoscopic technique of ureteral reimplantation is described, with emphasis on key technical modifications crucial to the ease of performance and a successful outcome.

Effects of temperature on tissue thermal injury and wound strength after photothermal wound closure.

BACKGROUND AND OBJECTIVES: Our goal was to determine the effect of temperature on the induction of tissue damage after laser-welded wound closure with and without albumin solder. STUDY DESIGN/MATERIALS AND METHODS: Multiple full-thickness skin incisions were made in a porcine model. Incisions were repaired by using a 1.32-microm laser at temperatures of 65 degrees C, 75 degrees C, 85 degrees C, or 95 degrees C with and without a 50% human albumin solder. The rate of apoptosis (programmed cell death) was quantified by counting the proportion of cells that stained positively for nuclear DNA fragmentation (nick end labeling). The distance that necrosis extended from the wound edge was also measured. The strength of the weld was measured with a tensiometer. RESULTS: For laser-welded repairs with solder, the amount of apoptosis at 65 degrees C and 75 degrees C was comparable to that of controls but became significantly elevated at 85 degrees C and 95 degrees C. The extent of necrosis was similar to that of controls at low temperature but also increased at 95 degrees C. Incisions repaired without solder showed increased necrosis compared with those repaired with solder at temperatures of 65 degrees C, 75 degrees C, and 95 degrees C at 0-0.5 mm from the incision. Wounds repaired at 85 degrees C and 95 degrees C showed more apoptosis in the absence of solder. The increased cell death at higher temperatures correlated with significantly decreased wound strengths at 3 days after repair in the solder group. A lower rate of cell death was observed in the solder group, which correlated with superior wound strength when compared with repairs without solder at days 0 (65-95 degrees C) and 3 (95 degrees C). CONCLUSION: Both apoptotic and necrotic cell death were used as quantitative measures of tissue injury and were accurate predictors of short-term wound strength. The addition of albumin solder decreased overall tissue injury. These results suggest that temperatures of 65-75 degrees C with solder provide the optimal conditions for maximizing acute wound strength and minimizing tissue injury.

Somatostatin-14 modulates acid-dependent inhibition of meal-stimulated gastrin via muscarinic pathways in dogs.

Intraluminal antral acidification inhibits gastrin and stimulates somatostatin-14 (S-14) release, but a functional relationship in the postprandial state has not been established. To examine whether meal-stimulated S-14 mediates inhibition of gastrin release by gastric acid, the effects of omeprazole on circulating levels of S-14 separated from S-28 by gel permeation chromatography, and gastrin were measured without and with atropine in dogs. Compared to controls, pretreatment with omeprazole decreased postprandial plasma levels of S-14 and S-28 (both P<0.01) and increased gastrin (P<0.001). Atropine selectively converted the S-14 response after omeprazole to a peak sixfold increase 40 min after meal ingestion (P<0.001), which was also significantly above S-14 values after atropine alone and controls, but reduced plasma levels of S-28 and gastrin to baseline. Infusions of the somatostatin analogue, cyclo-[7-aminoheptanoyl-Phe-D-Trp-Lys-Thr(BZL)] increased postprandial gastrin twofold above controls (P<0.05), and when administered after omeprazole reversed the inhibition of gastrin by atropine, without altering S-14 levels. In contrast, infusions of S-14, which simulated S-14 levels after omeprazole-atropine, and of [D-Trp8]-S-14, which abolished meal-stimulated S-14 responses, did not alter postprandial elevations of plasma gastrin. This study suggests that in conscious dogs muscarinic inhibitory pathways selectively regulate S-14 secretion, are amplified at neutral gastric pH and reciprocally link S-14 to gastrin secretion in the gastric phase of meal ingestion. Postprandial regulation of gastrin release by S-14 includes neurocrine interactions with muscarinic receptor activation; endocrine or paracrine regulation seem less likely.

Ureteral opening pressure: a novel parameter for the evaluation of pediatric hydronephrosis.

PURPOSE: The antegrade nephrostogram is an important tool in the evaluation of the upper urinary tract. However, the information currently provided by a nephrostogram is largely limited to anatomical details. To establish a meaningful pressure-flow parameter that may be incorporated into a routine nephrostogram, we evaluated the ureteral opening pressure (defined as the pressure at which contrast material is first seen beyond the suspected site of obstruction) and correlated these findings with the results of pressure-flow studies performed with an external infusion and/or furosemide induced diuresis. MATERIALS AND METHODS: A total of 52 renal units were studied under a prospective pressure-flow study protocol. All patients had grade 3 or 4 hydronephrosis (Society of Fetal Urology classification) and patient age range was 0.2 to 12 years (median 1.1). The suspected sites of obstruction were the ureteropelvic and ureterovesical junctions in 42 and 10 renal units, respectively. With the patient under general anesthesia 22 gauge percutaneous nephrostomy needles were inserted. Pressure-flow studies with an external infusion and/or furosemide induced diuresis were then performed. As the renal pelvic pressure progressively increased during the course of the pressure-flow studies, the renal pelvic pressure at which contrast material was first seen to appear distal to the suspected site of obstruction was recorded as the ureteral opening pressure. Ureteral opening pressures were compared to the results of the pressure-flow studies. RESULTS: With a positive test defined as renal pelvic pressure greater than 14 cm. water, positive ureteral opening pressures were associated with positive pressure-flow study results in 100% of the cases, regardless of which form of pressure-flow study was used or where the suspected site of obstruction was located. In contrast, negative ureteral opening pressures had specificities and negative predictive values of only 19 to 57%, depending on the form of the pressure-flow study and the suspected site of obstruction. CONCLUSIONS: An elevated ureteral opening pressure was 100% predictive of obstruction and may obviate the need for more elaborate pressure-flow analyses. However, if the ureteral pelvic pressure remained low, the possibility of a potentially significant obstruction could not be definitively eliminated and further evaluation was required.

Glucagon-like peptide-1-(7-36) amide and peptide YY mediate intraduodenal fat-induced inhibition of acid secretion in dogs.

Intraduodenal fat inhibits gastric acid secretion via the release of one or more hormonal enterogastrones thought to arise from ileocolonic mucosa. This study determined whether glucagon-like peptide-1 (GLP-1)-(7-36) amide and peptide YY (PYY), colocalized in L cells found in the ileum, mediate intraduodenal fat-induced inhibition of stimulated gastric acid, and evaluated the influence of cholecystokinin-A (CCK-A) receptor activation. Gastric acid secretion in response to duodenal perfusions of 8% peptone was measured in conscious dogs with gastric and duodenal cannulas. Intraduodenal administration of a 10% fat emulsion suppressed gastric acid secretion by 72 +/- 4% (P < 0.001) and increased plasma levels of GLP-1 and PYY by 44 +/- 5 and 46 +/- 4 fmol/ml, respectively (both P < 0.01). Pretreatment with the CCK-A receptor antagonist MK-329 completely reversed the inhibition of gastric acid by fat, suppressed rises of plasma GLP-1 (maximum change, 23 +/- 4 fmol/ml), and reduced plasma PYY responses to baseline. Intravenous infusions of 50 pmol/kg x h GLP-1 or PYY, which reproduced plasma elevations after intraduodenal fat, inhibited gastric acid secretion by 66 +/- 5% and 51 +/- 6%, respectively (both P < 0.01); coinfusions of GLP-1 and PYY abolished gastric acid secretion (P < 0.001) without influencing plasma gastrin or somatostatin. Pretreatment with 1500 pmol/kg x h of the GLP-1 antagonist exendin-(9-39) amide did not alter the magnitude of inhibition of gastric acid caused by exogenous GLP-1. These results indicate that GLP-1 and PYY released by intraduodenal fat, in part through CCK-dependent pathways, are major enterogastrones in dogs. This inhibitory action occurs independent of circulating concentrations of somatostatin and gastrin and appears to involve a GLP-1 receptor distinct from that mediating incretin effects.

Constant elevation in renal pelvic pressure induces an increase in urinary N-acetyl-beta-D-glucosaminidase in a nonobstructive porcine model.

PURPOSE: To clarify the physiological significance of renal pelvic pressure elevations encountered in the evaluation of hydronephrotic kidney we examined the effects of different levels of renal pelvic pressure on the induction of renal injury. MATERIALS AND METHODS: A nonobstructive porcine model was created in which the urine drained against a constant predetermined pressure gradient. Renal pelvic pressure of 10, 20 and 40 cm. was created in 2, 2 and 4 animals, respectively. During 18 to 23 hours serial urinary N-acetyl-beta-D-glucosaminidase levels were determined as an indicator of renal tubular injury. Tissue specimens were examined histologically and renal arterial blood flow was monitored. RESULTS: Urinary N-acetyl-beta-D-glucosaminidase levels in the kidneys subjected to 10 cm. water remained essentially unchanged. However, at 20 and 40 cm. water statistically significant increases were observed. Similarly, renal arterial blood flow was unchanged at 10 cm. water but it became significantly lower than in controls at 20 and 40 cm. water. Histological evaluation revealed mild to moderate tubular dilatation in the kidneys subjected to 20 and 40 cm. water. CONCLUSIONS: Excessively high collecting system pressure induced renal cellular injury, as reflected by an increase in urinary N-acetyl-beta-D-glucosaminidase levels. While renal pelvic pressure up to 10 cm. water appeared to be innocuous, renal cellular injury was evident within as little as 1 hour at renal pelvic pressures 20 cm. water or greater. The degree of N-acetyl-beta-D-glucosaminidase in the urine also correlated with a decrease in renal arterial blood flow.

Characterization of somatostatin receptor subtypes mediating inhibition of nutrient-stimulated gastric acid and gastrin in dogs.

Five somatostatin receptor subtypes (SSTR) have been cloned and characterized in various tissues, including the gastrointestinal tract. This study examined which receptor subtypes mediate the inhibitory actions of somatostatin on gastric acid secretion and gastrin release in conscious dogs. Peptide agonists with relatively high specificity for SSTR1-5 (somatostatin-14), SSTR2 (MK-678), SSTR3 (L-362823), and SSTR5 (L-362855) were infused i.v. after nutrient-stimulated gastric acid secretion and gastrin release with intraduodenal perfusions of 8% peptone and after secretagogue-stimulated acid secretion with gastrin (75 pmol kg-1 h-1) or histamine (20 micrograms kg-1 h-1). At 1000 pmol kg-1 h-1, the SSTR2 agonist inhibited peptone-stimulated acid output to baseline (P < 0.001), whereas the SSTR3 agonist decreased acid output by 58 +/- 6% (P < 0.01): the SSTR5 agonist was without effect. The SSTR2 agonist at 100 pmol kg-1 h-1 also abolished the rise of plasma gastrin. At 50 pmol kg-1 h-1 i.v. infusions of S-14, to simulate circulating S-14 rises after nutrients, decreased peptone-stimulated acid secretion by 58 +/- 8% (P < 0.01), whereas the SSTR2 agonist inhibited gastric acid by 96 +/- 2% (P < 0.001); the SSTR3 agonist was without effect. S-14 or the agonists at 50 pmol kg-1 h-1 did not alter elevations of plasma gastrin. S-14 and the SSTR2 agonist at 50 pmol kg-1 h-1 decreased gastrin-stimulated acid secretion by 42 +/- 8% (P < 0.01) and 78 +/- 4% (P < 0.001), respectively but the SSTR3 and SSTR5 agonists were without effect. In contrast, histamine-stimulated acid secretion was not altered by 1000 pmol kg-1 h-1 S-14 or the agonists. These results in conscious dogs suggest that the inhibitory actions of circulating S-14 on nutrient and gastrin-stimulated acid secretion include activation of the SSTR-2 subtype. Regulation of gastrin release by S-14 may also occur via SSTR-2, but not through an endocrine mechanism. Factors in addition to gastrin and histamine modulate intestinal protein-stimulated acid secretion yet include peripheral S-14 inhibition via SSTR2 activation.

Biocompatibility of silver-coated peritoneal dialysis catheter in a porcine model.

OBJECTIVE: Previous studies have shown that silver formulations coated onto implantable materials retard bacterial colonization and reduce the incidence of catheter-related infections. The objective of this study was to assess the histologic effects of sputter-coated silver/ silicone implants on host tissue. DESIGN: Sputter silver-coated silicone peritoneal dialysis catheter segments with and without Dacron cuffs were implanted in the subcutaneous fat and muscle in 4 pigs. Noncoated implants served as controls. The specimens were retrieved at 1, 2, 3, 4, 7, 8, 9, 10, 12, and 27 weeks. EXPERIMENTAL ANIMALS: Four 6-week-old male Yorkshire-Landrace pigs (5-6 kg) were used. MAIN OUTCOME MEASURES: Histologic parameters evaluated included the degree of inflammation, the number of giant cells, the extent of silver particulate inclusions, and the thickness of the capsules. All specimens were evaluated by a single blinded pathologist. Microbiologic analyses were also performed. RESULTS: The silver-coated catheters were associated with less inflammation than were the noncoated catheters, both in fat and muscle (p = 0.04). The number of giant cells was also lower around the silver-coated than the non-coated catheters, which were implanted in subcutaneous fat (p < 0.05). Particulate inclusions compatible with silver or silver oxide were observed only in tissue around silver-coated implants (p < 0.0001). The thickness of the capsules and the extent of the inflammatory zones were not significantly different. There was no evidence of infection-related changes. CONCLUSIONS: These data suggest that the sputter silver coating does not act as a significant tissue irritant.

Pressure decay half-life: a method for characterizing upper urinary tract urine transport.

PURPOSE: We examined the pressure dynamics of hydronephrotic kidneys after elevated renal pelvic pressure developed. MATERIALS AND METHODS: A total of 40 patients (44 renal units) 0.2 to 12 years old was evaluated. Transiently elevated renal pelvic pressure was induced with a percutaneous nephrostomy infusion. After renal pelvic pressure increased the infusion was stopped and the subsequent decrease in pressure with time was plotted as a pressure decay curve. The rapidity of the decrease in renal pelvic pressure was then quantitated as a half-life for each pressure decay curve. Pressure decay half-lives were compared to corresponding pressure flow study results and diuretic nuclear renography half-lives. RESULTS: Renal units without elevated renal pelvic pressure during infusion at a high physiological flow rate were associated with relatively rapid pressure decay, whereas those with elevated renal pelvic pressure during infusion were associated with much slower pressure decay (p < 0.0001). Diuretic nuclear renography half-lives had no correlation with collecting system pressure dynamics. CONCLUSIONS: Pressure decay half-life provides an objective quantitative measure of the relative tendency for elevated renal pelvic pressure to persist. When used in conjunction with other diagnostic modalities, it may be a useful parameter for a comprehensive assessment of the risk of pressure induced injury in hydronephrotic kidneys.

Contradictory supranormal nuclear renographic differential renal function: fact or artifact?

We previously reported contradictory supranormal nuclear renographic differential renal function in cases of unilateral hydroureteronephrosis, in which the kidneys with hydroureteronephrosis paradoxically had a greater differential function than the contralateral normal mate, based on diethylenetriaminepentaacetic acid (DTPA) nuclear renography. To evaluate whether DTPA supranormal differential function represented true hyperfunction, patients with DTPA supranormal differential function were evaluated with dimercaptosuccinic acid (DMSA) nuclear renography and the results were compared. A total of 16 patients with unilateral hydronephrosis was identified to have DTPA differential function of 53% or more. They were younger than age 1 year and had never undergone any urological surgery. In all 16 patients the DMSA differential function (mean 51.1%, range 42 to 57%) was lower than their own corresponding DTPA differential function (mean 58.3%, range 53 to 66%, p < 0.0001). In addition, the DMSA differential function was not significantly different from the intuitively anticipated mean of 50% (p = 0.48). The DTPA supranormal differential function identified in our patients was not corroborated by the DMSA differential function. With recent evidence that DMSA differential function may be a better predictor of outcome following relief of unilateral ureteral obstruction consideration should be given to using DMSA as a potentially more relevant method for differential function measurement in the setting of unilateral hydronephrosis. Conversely, until the potential deficiencies of DTPA are fully understood caution should be exercised in the interpretation of DTPA differential function in the setting of hydronephrosis.

Evaluation of pediatric hydronephrosis using individualized pressure flow criteria.

In pursuit of a diagnostic modality better able to assess collecting system urine transport characteristics while operating within physiological ranges, a new set of guidelines for the pressure flow study was proposed. An infusion rate individualized for each patient was chosen based on a calculated estimate of the maximum physiological urine output, adjusted for patient size and age. The upper limit of normal renal pelvic pressure used was 14 cm. water. We evaluated 37 renal units with grade 3 or 4 hydronephrosis with the individualized pressure flow study. Patient age ranged from 0.2 to 12 years (median 1.1). Calculated individualized infusion rates ranged from 1.3 to 12.5 ml. per minute and resulting renal pelvic pressures ranged from 7 to greater than 40 cm. water. In each patient the corresponding renal pelvic pressure resulting from a fixed 10 ml. per minute infusion rate was uniformly equal to or higher than the corresponding individualized study pressures (p < 0.0001). Disagreement between the individualized and fixed rate pressure flow studies was highest in the younger patients. The correlation coefficient between diuretic nuclear renography half-times and individualized pressure flow results was 0.09, indicative of a random association between the 2 variables. By using individualized infusion rates based on the calculated estimate of the maximum physiological urine output, much of the falsely high pressures induced by nonphysiologically high fixed infusion rates in pediatric patients can be avoided.

Donor aortic cuff reduces the rate of anastomotic arterial stenosis in pediatric renal transplantation.

A total of 333 pediatric renal transplantations performed at our institution between January 1977 and July 1994 was retrospectively reviewed to provide guidelines for minimizing the incidence of transplant renal artery stenosis. The patients who had renal artery stenosis were 3 months to 17.5 years old (median age 9.3 years) at the time of transplantation and the condition was diagnosed 2.2 months to 2.5 years (median 4.2 months) after transplantation. Renal artery stenosis was diagnosed in 19 transplants (19 of 333, 5.7%) as a result of severe hypertension or renal function deterioration. Stenosis occurred at the anastomosis in 7 cases (37%) and distal to the anastomosis in 12 (63%). Transplantations performed with a donor aortic cuff resulted in a lower rate of renal artery stenosis at the anastomosis (0 of 193, 0%) compared to those performed without a cuff (7 of 140, 5.0%, p = 0.0021). The rate of renal artery stenosis distal to the anastomosis was not different regardless of whether a cuff was used (5 of 193 cases, 2.6%) or not (7 of 140, 5.0%, p = 0.37). End-to-end anastomoses to internal iliac arteries, which were always performed without cuffs, had a particularly high rate of renal artery stenosis (3 of 10, 30%) compared to end-to-side anastomoses performed without cuffs (4 of 130, 3.1%, p = 0.0080). Bench surgery or multiple renal arteries did not adversely influence the rate of renal artery stenosis. With prompt diagnosis and treatment the actuarial graft survival of the transplants with renal artery stenosis was similar to that of the transplants without renal artery stenosis (p > 0.05).

Voiding efficiency after ureteral reimplantation: a comparison of extravesical and intravesical techniques.

The purpose of our study was to examine postoperative changes and recovery in voiding efficiency after intravesical and extravesical ureteral reimplantation. Retrospective review was performed of 188 cases. Inclusion criteria were the presence of primary vesicoureteral reflux and the absence of previous lower urinary tract surgery. Voiding efficiency after ureteral reimplantation was assessed based on post-void residual volume measurements. It was found that postoperative voiding efficiency of patients in the extravesical unilateral group was similar to that in the intravesical group, while the extravesical bilateral group had a statistically significantly higher proportion of patients with transient voiding inefficiency. A statistically higher proportion of those in the extravesical bilateral group also required some form of urinary catheter drainage for a longer period. However, on more prolonged followup all evaluable patients in the 3 groups fully regained voiding efficiency.

Histologic studies of intravesical oxybutynin in the rabbit.

Intravesically applied oxybutynin has been reported to have no significant systemic anticholinergic side effects, with excellent efficacy in the treatment of neurogenic bladder dysfunction. Currently, the morphologic effects of intravesical oxybutynin on the local bladder tissue are not well established. It is the purpose of this study to address this issue in an animal model. Thirty-nine New Zealand White female rabbits were catheterized daily and intravesical solutions instilled for as long as 30 days. In part A of the study, the overall histologic effects of intravesical oxybutynin were examined by comparing oxybutynin with saline administration. Part B of this study compared the relative effects of crushed oxybutynin tablets and pure oxybutynin powder. The bladder histology and urine microbiological studies were analyzed in a blinded fashion. We found that the crushed oxybutynin tablets and saline administered intravesically produced similarly mild inflammation in the bladders (p < 0.05). When we compared the crushed oxybutynin tablets and pure oxybutynin powder, however, the crushed tablet group was found to have a mild eosinophilic infiltrate seen in 5 of 9 animals, which was not observed in any of the animals in the other groups (p = 0.029). Qualitative and quantitative analyses of the microbiological findings were not different among the different groups (p > 0.05). Our findings support the clinical use of intravesical oxybutynin as being safe for local tissue. However, consideration should be given to the use of the pure powdered form of oxybutynin, since the crushed oxybutynin tablets may lead to allergic reactions.

Testicular seminoma presenting with features of androgen excess.

A 32-year-old white man presented with worsening acne and noticeable increase in muscle bulk. On examination, a firmer area with a granular consistency was noted in the right testis. A right radical orchiectomy was performed and the histologic findings were those of a typical seminoma associated with marked Leydig cell hyperplasia. A solitary right iliac lymph node metastasis, but not the primary seminoma, contained human chorionic gonadotrophin- (HCG) producing syncytiotrophoblast, which was regarded as the hormonal stimulus for Leydig cell hyperplasia and elevated serum testosterone. This seems to be the first report of testicular seminoma presenting with symptoms of androgen excess.

Intrarenal resistive index correlates with renal pelvis pressure.

Elevation in the intrarenal resistive index has been suggested by many to be a physiological parameter useful for detecting functionally significant hydronephrosis. It is currently unknown whether the intrarenal resistive index changes truly reflect the changes in collecting system pressure or whether they are simply a coincidental epiphenomenon. The purpose of this study is to establish the relationship between intrarenal resistive index and collecting system pressure. Between August 1992 and October 1993, 9 patients younger than 1 year underwent a percutaneous pressure-flow study as part of hydronephrosis evaluation. During the pressure-flow study intrarenal resistive index was measured serially with simultaneous renal pelvis pressure readings. In all patients the index increased as the renal pelvis pressure increased. Furthermore, using the experimentally derived proximal tubular pressure of 14 cm. water as the probable threshold for functionally normal collecting system pressure, it was found that all intrarenal indexes of 82% or less corresponded to renal pelvis pressures of less than 14 cm. water, while all of those greater than 82% corresponded to renal pelvis pressures greater than 14 cm. water. By combining several lines of evidence, it appears probable that as maximal diuresis induced by physiological and pharmacological means leads to acute transient elevation in renal pelvis pressure in a functionally obstructed collecting system, the intrarenal resistive index is capable of reflecting this dynamic elevation in renal pelvis pressure and potentially able to distinguish physiologically significant upper urinary tract obstruction from nonobstructive dilatation.