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Congenital megalourethra

Ramnik Patel, Abraham Cherian, Francisca Yankovic, Naima Smeulders, Divyesh Desai, Peter Cuckow
Department of Paediatric Urology,
University College London Hospital NHS Foundation Trust and
Great Ormond Street Children’s Hospital, London, UK

 

Abstract

A case is reported of congenital megalourethra in a 3-year-old boy who presented with ballooning of the distal portion of ventral aspect of his urethra during micturition followed by postmicturition dribbling. Micturating cystourethrogram confirmed the diagnosis and he underwent examination under anaesthesia, cystourethroscopy, Nesbitt’s reduction urethroplasty, spongioplasty and meatoplasty uneventfully with excellent anatomical, functional and cosmetic results. Congenital megalourethra may be missed unless actively sought (our case had even had a previous orchidopexy for undescended testis without any suspicion about his penis). The localised scaphoid variety has a better prognosis compared to the diffuse fusiform variety. Associated minor structural anomalies may also need attended to while the urethra is being reconstructed.

Key words: congenital scaphoid megalourethra, reduction urethroplasty, spongioplasty, meatoplasty, frenuloplasty

 

Correspondence

Mr Peter Cuckow MD, FRCS, FRCS (Paed Surgery)
Consultant Paediatric Urologist, UCLH and GOSH, London
Department of Paediatric Urology
University College London Hospitals and
Great Ormond Street Children’s Hospital NHS Foundation Trust
London, United Kingdom
Phone: 00447956896641
Fax: 00441162586089
E mail: This email address is being protected from spambots. You need JavaScript enabled to view it. , This email address is being protected from spambots. You need JavaScript enabled to view it.

 

Introduction

Congenital megalourethra is a rare urogenital malformation characterized by dilation and elongation of the penile urethra associated with absence or hypoplasia of the corpora spongiosum and cavernosa [1, 2]. It has been reported in monochorionic twins and may be associated with other congenital malformations [3-4]. To date, only a few prenatally and postnatally diagnosed cases have been reported. We report an interesting case that was being seen for other reasons in both the community and in hospital and yet eluded recognition for 3 years.

Case report

A 3-year-old boy was referred to us with selective bulging on the distal part of the ventral aspect of his penis during micturition, with deviation of the urinary stream, for the past 4 months. His paediatrician suspected a possible urethral diverticulum and referred him to us for further assessment.

His mother had a background of previous intrauterine death and maternal gestational diabetes. He was born at 36 weeks’ gestation by spontaneous vaginal delivery and was small for age. Both his testes were undescended at birth; the left testis spontaneously descended, but he required right orchidopexy at the age of 1 year. He also had gastro-oesophageal reflux and constipation, both treated medically.

On initial examination, his penis appeared normal. The foreskin was retractable. During micturition, a distal urethral bulge was quite evident,more prominent on the left side of the penile shaft, and deviation of the urinary stream was observed towards the right side. A differential diagnosis of anterior urethral valves, urethral diverticulum, and the localized scaphoid variety of megalourethra was considered.

His urine, haematological and biochemical investigations including renal, liver and bone profiles were normal. Renal ultrasound was normal. Micturating cystourethroscopy (MCUG) showed scaphoid distension of the distal urethra (confirming the diagnosis of scaphoid megalourethra, the eccentric pattern of the contrast differentiating it from the very much more common physiological “ballooning” of the foreskin); the posterior urethra was somewhat “baggy”, but there were no posterior urethral valves; his bladder appeared normal, with no vesico-ureteral reflux (Fig.1). Uroflowmetry studies were inconclusive, due to only small volumes being voided.

Figure 1. MCUG- Scaphoid Megalourethra

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Examination under anaesthesia revealed a straight penis with a short foreskin. The external urethral meatus appeared slightly narrow, so was dilated. Cystourethroscopy using a 9.5 French gauge 0-degree telescope demonstrated scaphoid distension of the distal urethra and it was brilliantly transilluminant in the bright cystoscopic light (Fig. 2). The posterior urethra and bladder appeared normal.

Figure 2. Clinical (A), voiding (B) and cystoscopic views- note the transillumination (C)

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He underwent circumferential incision, degloving of the skin from the shaft of the penis after leaving a size 10 urethral stent in situ (Fig. 3A). A spongiosal defect was seen distally splitting in a ‘V’ shape and the megalourethra bulged through the defect on inflating with fluid (Fig. 3B). The distal spongiosum was hypo plastic ventrally through which the localized scaphoid variety of megalourethra taking the urethral mucosa very close to the skin with absent spongiosum ventrally (Fig. 3C). The scaphoid redundant megalourethra was excised in an elliptical fashion and then the urethral mucosal layer was closed followed by spongiosum tissue which was split in a V shape was brought over as second vascular tissue followed by creation of the frenulum. He underwent uneventfully a Nesbit reduction urethroplasty after excision of an elliptical segmental of elongated and dilated urethra followed by spongioplasty, frenuloplasty and meatoplasty (Fig. 3D).

Figure 3. A to D: Operative pictures- A. circumferential degloving; B. Corporal defect (S and SS-spongiosum split) and protrusion of megalourethra (SCMU); C. excision of redundant megalourethra, with urethral stent in situ; Note urethral mucosa and split spongiosum on both sides D. Completed procedure and end result.

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His post-operative period was unremarkable and at 1-year follow-up, he is well and asymptomatic. He has had an excellent anatomical, functional and cosmetic result.

Discussion

It is possible to suspect congenital megalourethra antenatally by ultrasound anomaly scan at around 20 weeks’ gestation and fetoscopy later despite the fact that it is only clearly demonstrated while voiding [1, 4-6].

Megalourethra is a rare congenital disorder involving the anterior urethra. It is subdivided into two types: a fusiform generalized variety (severe) and a scaphoid localized, distal variety (mild) (Fig. 4).

Figure 4. Schematic illustration showing scaphoid and fusiform variety of congenital megalourethra (CMU)

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The distal scaphoid variety is usually isolated, or has only minor associated anomalies, and has a very good prognosis. The diffuse fusiform variety, on the other hand, is associated with many other congenital urogenital and systemic anomalies including urethral atresia or valves, urethral duplication, massive bilateral vesico-ureteral reflux, upper tract anomalies, undescended testis, abdominal musculature deficiency syndrome, VACTERL association, anorectal malformation, and hypoplastic left heart, and so one needs to look actively for these [7-9].

Association with maternal diabetes has been implicated and our case had maternal gestational diabetes [10].

The clinical presentation is with ballooning and deformity of the penile shaft during micturition, or relates to other associated anomalies and complications. Clinical observation of voiding is characteristic. Uroflowmetry studies may be needed in older patients to rule out associated urethral obstruction and anomalies. Retrograde urethrography, voiding cystourethrography and cystourethroscopy are diagnostic.

Megalourethra can be associated with serious consequences including intrauterine death or spontaneous abortion, pulmonary hypoplasia, renal insufficiency, voiding and erectile dysfunction, recurrent urinary tract infections, and urolithiasis, some of which may require attention first before surgical correction of the urethra [11]

Prenatal diagnosis and antenatal spontaneous resolution has been reported [12]. In most instances of postnatally diagnosed cases, surgical correction should be undertaken if possible as the untreated condition is associated with complications and morbidity of recurrent urinary tract infection, stone formation, obstructive uropathies, renal insufficiency, oligohydroamnios and pulmonary hypoplasia leading to fetal demise in diffuse variety and associated congenital anomalies in such cases may contribute to co-morbidities.

The surgical management includes Nesbit reduction urethroplasty with spongioplasty, frenuloplasty, and/or meatoplasty, as required, in a single stage in most scaphoid varieties. The excess urethral tissue of the megalourethra may be used to reconstruct any associated atretic or stenotic urethra. Alternatively, in severe forms, a graft may be taken from the inner foreskin, buccal mucosa or post-auricular skin in a twostage repair [8-9].

The prognosis is generally good, but in extreme cases it may lead to demise of the foetus prenatally or postnatally due to pulmonary hypoplasia and/or renal insufficiency [13].

Conclusion

Megalourethra, although congenital, may be missed in the prenatal and postnatal period. Diagnosis of these entities is elusive unless the doctor is looking for them, so health professionals should be aware of these uncommon congenital anomalies. The non-specific symptoms mentioned here can be a valuable clue for diagnosis. Watching the act of voiding in clinic or via parental photographs or video is invaluable. The anterior urethra should be carefully evaluated for such anomalies. MCUG or retrograde urethrography and trans-illumination at cystoscopy may prove helpful in doubtful cases. Surgical correction is advisable whenever possible to reduce morbidity.

Acknowledgement:

We are grateful to Mr David Marshall MD, FRCS Consultant Paediatric Urologist at Royal Belfast Hospital for Sick Children, Belfast, Northern Ireland for peer review with his advanced professional and linguistic editorial skills.

Conflict of Interest: None

 

 

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