Importance of urinary flow studies after hypospadias repair: A systematic review
Ricardo González M.D., Kinderchirurgie, Kinderkrankenhaus auf der Bult, Janusz-Korczak-Allee 12, 30173 Hannover, Germany. Email: email@example.com
A systematic review was performed of publications relating to the results of urinary flow studies after hypospadias repair dating back to 1978, when what appears to be the first publication on this topic was found. The literature search was performed using the key words “hypospadias” combined with “urinary flow”, “urine flow”, “uroflow”, “uroflowmetry”, and “long-term”. We also reviewed the abstracts and full-length articles cited in the reference list of selected articles. Criteria for inclusion in the present systematic review included descriptions of patient selection, surgical technique, the severity of disease (proximal vs distal), and the method used to determine uroflow, as well as a definition of urethral obstruction. In all, 339 article titles were found. Of these, 25 abstracts appeared relevant and the full text of these articles were reviewed, with 22 of the papers included in this review. Sixteen reports had appeared in the literature since 2001, compared with six between 1978 and 2000, suggesting an increasing interest in this topic. On the basis of the results of the present systematic review, we recommend that asymptomatic children operated on for hypospadias in infancy should have one flow study after toilet training, with that study repeated if the results are abnormal. It appears that early abnormal flows improve spontaneously, so that children operated on after toilet training who are asymptomatic should undergo their first uroflow measurement 1 year after surgery. Children with obstructed flow parameters or borderline flows should be followed until adulthood, until long-term follow up studies clarify the significance of abnormal flow parameters. Given the present findings, we anticipate that in the next two decades urologists will need to treat a number of men with strictures resulting from hypospadias repairs performed in childhood.
Hypospadias is a common anomaly of the male genitals that varies considerably in severity. Severe cases, with marked ventral curvature of the penis and a meatus in the proximal part of the penile shaft or more proximally, require repair to allow penetration of the penis into the vagina and ejaculation within it. Nevertheless, most cases are mild and surgical correction is undertaken mostly for cosmetic reasons at the request of the parents or on the advice of the pediatrician or surgeon.
The goals of surgical repair are to create a cosmetically acceptable appearance, a straight penile shaft during erection and a urethra that opens distally at the glans or the corona. No less important, the urethra, if reconstructed, should have an adequate caliber and grow with the child. Urinary flow studies provide an objective measurement of urethral function.
Evaluation of long-term results of hypospadias repairs is important because the operation is usually performed in infancy or childhood in the hope of providing satisfactory results in adult life. Several instruments have been devised to attempt to objectively evaluate the results of hypospadias repair,1,2 but most reports address urethral function on the basis of the presence of voiding symptoms. Although in acquired strictures symptoms correlate well with flow patterns,3 a patient may not recognize voiding abnormalities resulting from a stricture caused by an operation performed before toilet training. In these cases, a urinary flow study may better reflect urethral function.
In the present article we report the results of a systematic review of publications addressing the value of urinary flow studies in the evaluation of the results of hypospadias operations.
A systematic review was performed of publications relating to the results of urinary flow studies after hypospadias repair dating back to 1978,4 when what appears to be the first publication on this topic was found. PubMed was searched using the key words “hypospadias” combined with “urinary flow”, “urine flow”, “uroflow”, “uroflowmetry”, and “long-term”. In addition, abstracts and full-length articles cited in the reference list of selected articles were reviewed.
The criteria for inclusion in the present systematic review included descriptions of patient selection, exclusion criteria, surgical technique, the severity of disease (proximal vs distal), and the method used to determine uroflow, as well as a definition of urethral obstruction. In the present study, we considered obstruction on uroflowmetry to be the presence of a plateau pattern and maximum flow (Qmax) below the 5th percentile on a standard nomogram or two standard deviations (SD) below the mean normal for age.
The literature search yielded 339 article titles with some repetitions. From these, 25 abstracts appeared relevant and the full text articles of these papers were reviewed. Of these, 22 were included in the present review. Twenty articles were in English, one was in Italian, and one was in French. Sixteen reports had been published since 2001, compared with six between 1978 and 2000, suggesting an increasing interest in this topic.
Two studies compared different techniques in a non-randomized fashion.5,6 One article compared two different techniques to construct protecting flaps with the same urethroplasty technique in a randomized fashion in adults.7 Of interest, four papers reported preoperative uroflow measurements.8–11 Most studies involved toilet-trained children and uroflowmetry was performed with a rotating disc instrument, but two studies used Doppler ultrasound and included children before toilet training.8,9 Articles that used Qmax compared it to a control population or, more frequently, to normal values reported in well-established nomograms.
Results according to technique
Tubularized incised urethral plate
Eleven articles addressed the incidence of postoperative obstruction as defined by either a plateau curve or Qmax below the 5th percentile. Most of these series excluded patients with symptomatic obstructions requiring treatment. When serial flows were performed, only the latest was taken into consideration. Of 378 patients reported, 93 (24.6%) met the uroflow criteria of obstruction5–8,10,12–17 (Table 1).
Table 1. Incidence of obstructive uroflows after tubularized incised urethral plate repair†
|Scarpa et al.5||19||8||42||Plateau pattern or under 10th percentile (Togurinomogram)||Distal|
|Braga et al.6||24||16||66.7||Under 25th percentile (Togurinomogram) and plateau pattern||Penoscrotal|
|Burgu et al.7||42||3||7||Qmax and pattern||Distal or mid-penile|
|Wolffenbeuttel et al.8||39||6||15||Not given||Not stated|
|Tuygun et al.10||63||10||16||Qmax <2SD on nomogram (Gaum) and plateau pattern||Distal|
|Hammouda et al.12||45||14||31.1||Qmax <2SD on nomogram||Distal shaft or more distal|
|Andersson et al.13||26||12||46||Qmax below 5th percentile (Miskolc nomogram)||Not stated|
|Holmdahl et al.14||29||11||38||Not given||Not stated|
|Kaya et al.15||28||2||7||Not given||Not stated|
|Marte et al.16||21||3||14||Not given||Not stated|
|Saggiomo et al.17||42||8||19||Not given||Not stated|
|Total||378||93||24.6|| || |
In situ tubularizartion without incision of the plate (Duplay, King, or Thiersch-Duplay)
In one series of 71 patients operated on using the Duplay technique (tubularization of the plate without dorsal incision), 20% had obstructed uroflows as defined by a Qmax under the 5th percentile.18
Meatal-based flap (Mathieu)
Three papers addressed flow evaluated after a modified Mathieu operation. Of 85 patients available for analysis, 15 (17.6%) had flow patterns or values compatible with obstruction.5,19,20
Meatal advancement and glanuloplasty and urethral advancement (Beck)
One publication each addressed flow values after meatal advancement and glanuloplasty (MAGPI) and urethral advancement (Beck's technique). Five percent of patients operated on using the MAGPI technique21 and 2% of those undergoing urethral advancement developed meatal stenosis.22
There are isolated publications addressing the functional results of other types of hypospadias correction. For example, Reid et al.23 performed postoperative flow studies at a mean of 6 years after two-stage reconstruction using the Bretteville technique and found that 20% of patients had Qmax below the 5th percentile. Anwar et al. evaluated patients repaired with the Koyanagi technique of parameatal flaps and found obstructive flow patterns in three of 21 children who had no fistulas.24 Urethroplasties using preputial island flaps as tubes or onlays were investigated by Jayanthi et al.,25 who found that of 80 patients selected on the basis of an absence of a fistula or persistent stricture, 31% had Qmax less than 2SD below the normal. Al Sayyad et al. evaluated patients with failed primary repairs that were reoperated using a variety of techniques and found no obstructive flows in 16 of 28 patients who had no complications.26
Two articles compared the results of uroflows following two different techniques of urethroplasty and one compared flows before and after repair.
Scarpa et al.5 compared flows in 19 patients with coronal of more distal hypospadias repaired with meatal based flaps and 22 with the tubularized incised urethral plate (TUIP) technique. Patients in both groups were of comparable age and were followed for a mean of 20 months. Obstructive flows were observed in 14% of patients undergoing Mathieu repairs and in 42% of those undergoing TUIP (P = 0.07). In the group undergoing Mathieu repair, all flows normalized with dilatation, but in three patients subjected to TUIP the flow remained obstructed. Braga et al.6 studied 75 patients with penoscrotal hypospadias operated on using either the TUIP or onlay preputial flap techniques at a mean age of 17 months. At a mean age of 5 years, seven of 21 (33.3%) patients who had onlay repairs had obstructed plateau flow patterns compared with 16 of 24 (66.7%) who had the TUIP operation. Wolffenbeuttel et al.8 studied 42 children with a mean age of 16 months before and 3 (n = 28) and 9 months (n = 11) after TUIP. The control group consisted of of 51 boys aged 0–3 years old (mean age 11 months). Uroflow was measured by ultrasound and revealed a plateau pattern in 6% of children before the operation and in 41% during the long-term follow-up.
Uroflow in non-operated hypospadias
Four publications reported results of uroflow studies in patients with hypospadias before surgical correction. Tuygun et al.10 reported meatal stenosis with obstructed flow patterns in five of 63 children with a mean age of 7 years before they underwent correction. Using an ultrasound probe to measure flow, Olsen et al.9 studied 21 infants with hypospadias (mean age 14 months) and compared them with an age-matched control group. Plateau-shaped curves were seen in 31% of patients and in none of the children in the control group. In that report, meatal calibration was not correlated with obstructive flow patterns.
Wolffenbeuttel et al.8 also studied flows by ultrasound in 42 infants with hypospadias before repair and compared them with a control group. Although intermittent and staccato patterns were common, only 6% of patients and 3% of controls had a plateau pattern compatible with obstruction. Finally, Maylon et al.11 stated that “In the majority of the hypospadias population a truncated curve is seen”, with maximum flows around the 5th percentile of the normal population.
Most publications reported patients with flows that did not fulfill the criteria for obstruction and yet were not bell shaped or had Qmax between the 5th and 25th percentiles. Saggiomo et al., followed 10 children with borderline flows after hypospadias correction and reported that seven remained stable but three developed symptoms and a clearly obstructed pattern;17 Andersson et al. reported two such cases.13
The present review suggests an increasing interest in the evaluation of urethral function after hypospadias repair. Urinary flow measurements reflect both urethral and bladder functions. If we assume that most patients with hypospadias have normal bladder contractility, the results of urinary flow rates and the shape of the low curve reflect urethral function. It is well known that, in urethral strictures, Qmax is diminished and the flow pattern loses its normal bell shape and becomes flattened. The influence of the elasticity of the urethral wall (urethral compliance) on the urinary flow parameters is less clear. In an experimental model, the presence of a stiff segment at the distal end of a tube with a wall compliance similar to the urethra resulted in a decrease in the maximum flow rate;27 if these results can be extrapolated to an in vivo situation, it may be that a rigid neourethra may result in a diminished flow rate even if it has an adequate caliber.
In the present paper we defined obstructive flow as a flow pattern that was flat or a Qmax below the 5th percentile or less than 2SD below the normal mean using a control group (or, more frequently, a standard nomogram taking into account age or body size).
The question of whether abnormal uroflow is part of the malformation or a result of the operation performed to correct it is pertinent to the interpretation of postoperative flows. One article reported decreased Qmax and plateau curves in almost one-third of infants with hypospadias before repair.9 But in the study of Wolffenbeuttel et al., who also used ultrasound to measure flow, the percentage of infants with plateau patterns before repair was only 6%.8 Olsen et al.9 found no correlation between abnormal flows and urethral calibration, but Tuygun et al., studying an older group of boys, reported that 8% had an obstructed flow pattern before surgery and all had a meatal stenosis at the time of the operation.10 The fact that in many cases an obstructive flow pattern resolves with treatment of the stenosis suggests that it represents a real obstruction.5,19
The significance of a plateau flow pattern or a Qmax below the 5th percentile is not known because there are no reports of the long-term follow-up of asymptomatic patients with obstructive flows. Saggiomo et al. reported that three of 10 patients with Qmax between the 5th and 25th percentiles developed symptoms and required treatment,17 and Andersson et al. reported tow such cases.13 Most series reviewed excluded patients with symptomatic strictures or fistulas; therefore, the results of flow studies reported included only “successful operations” in asymptomatic children and so the incidence of postoperative urethral stenosis is likely higher than the percentage of patients with obstructive uroflows.
Overall, between 7% and 67% of patients operated on for hypospadias end up with an obstructive flow. The techniques of distal hypospadias repair that are less commonly associated with obstructive flow parameters are MAGPI and urethral advancement,21,22 but these findings are based on results from a single publication for each technique.
Of concern is that one of the most commonly used techniques, namely TUIP, results in obstructive flow in 24.6% of patients reported in 11 series. The second most commonly studied surgical technique, urethroplasty with a meatal based flap (three reports), resulted in obstruction in 18% of cases.
We identified only one report that analyzed flows after a staged repair, in which 20% of patients had flows below the 5th percentile.23 It is not known whether patients without symptoms and obstructed flow patterns should be investigated and treated. On the basis of the results of the present systematic review, we recommend that asymptomatic children operated on for hypospadias in infancy should have one flow study after toilet training and that this study should be repeated if the results are abnormal.
It appears that early abnormal flows improve spontaneously,13,14 so that children operated on after toilet training who are asymptomatic should have the first uroflow measurement 1 year after the surgery. Children with obstructed flow parameters or borderline flows should be followed until adulthood, until long-term follow up studies clarify the significance of abnormal flow parameters. Although considerable progress has been made in the repair of hypospadias,28 the present findings suggest that in the next two decades urologists will need to treat a number of men with strictures resulting from hypospadias repairs performed in childhood.
Conflict of interest