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2004-02-12-10 Megalourethra with horseshoe kidney © Sosa

Megalourethra with horseshoe kidney

Alberto Sosa Olavarria, MD, M.O. Sosa Palavicini, MD

Perinatology Unit, Carabobo University, Valencia - Venezuela, Maternidad Privada Las Acacias. Valencia Venezuela

Megalourethra, a rare congenital disorder involving the penile urethra, is subdivided into two types, fusiform and scaphoid. We present a case of congenital megalourethra scaphoid type, the corpus spongiosum was absent with normal corpora cavernosa, without obstructive distal urethra, diagnosed prenatally at 21 weeks of gestation. Ultrasound features was an enlarged and deformed penis with urethra dilatation, megacyst, mild hydronephrosis, single umbilical artery and horseshoe kidney were also found. The anomaly of the penile urethra is discussed, and 41 cases from the English and Spanish literature are reviewed.

Case report
A 30-year-old G1 was transferred to the authors after a routine sonogram during early gestation revealed a fetal cystic mass in the abdomen. Subsequent ultrasound revealed fetal megalourethra, megacystis, horseshoe kidney with echogenic renal parenchyma, mild hydronephrosis, single umbilical artery and normal amniotic fluid volume and a fetus consistent with 21 weeks (figures 1-8). Chromosome analysis revealed a normal male karyotype.

These images show the striking cystic structure in the penile urethra and slight distension of the bladder. These 2 findings are characteristic of megalourethra.

...and these of course represented a horseshoe kidney !


Schematic representation of the features



  Megalourethra (longitudinal view) and cavernous corpora (arrow) in axial plane.

Nesbit (22, 23) was the first described in 1954 as “a congenital dilatation of penile urethra without distal obstruction”. This rare abnormality is characterized by severe dilatation of the penile urethra caused by an absence of corpus spongiosum (scaphoid type) or with deficiency of both corpus spongiosum and cavernous corpora (fusiform type).   

                                                                   Fusiform type associates a prune-belly syndrome.

 This condition is usually associated with many congenital malformations especially abdominal wall, genitourinary, gastrointestinal and vertebral (1-37). The distinction between scaphoid and fusiform megalourethra seems arbitrary, and the disorder is better viewed as a spectrum rather than as 2 distinct entities (1).
An association between urethral atresia and the prune belly syndrome (PBS) has been recognized (2, 28) but in this case an obstructive phenomenon early in gestation leading to irreversible damage to the genitourinary tract and abdominal wall. In other hand (18) justify categorization of megalourethra how the minor forms of prune belly syndrome.
Rare. Fewer than 90 cases of megalourethra had been reported in the literature.

1. Failure of urethral recanalization as a cause of megalourethra (Stephens-Fortune)
2. Temporary obstruction during early development may be a etiologic factor in fusiform type
3. Failure of development of erectile tissue may be a etiologic factor in scaphoid type
4. Abnormal mesodermal development: developmental arrest of the mesenchymal elements of the penis would lead to severe laxity and defective development of the erectile tissue
The pathogenesis of the prune belly syndrome (PBS) remains controversial (2, 28) but two theories predominate. The first theory supports an obstructive phenomenon early in gestation leading to irreversible damage to the genitourinary tract and abdominal wall. The second theory suggests mesodermal injury between the 6th and 10th weeks of gestation as the primary abnormality (34).

Associated anomalies:
Megalourethra often had been associated with other severe anomalies (1-37): Prune-belly syndrome (PBS) in 27%, genitourinary, and intestinal (70%), others systems (30%): Cloacae, vertebral, anal, cardiac, tracheal, esophageal, renal, limb malformations (VACTERL and VATER association), duplication of urethra, renal dysplasia , megacyst, polycystic kidney, brachydactiylia, unilateral renal hypoplasia, colonic malrotation, hydronephrosis, hydroureteronephrosis, duplication of the ureter, cryptorchydism and vesicocutaneous fistula . The urethral stenosis can be observed in Williams-Beuren Syndrome, Fraser synd., and Melnick-Needles syndrome.

Prenatal diagnosis:
Cystic dilatation and enlargement of the penis, in the fusiform type we can not observed both corpus spongiosum and cavernous corpora. In the scaphoid type we can observed the glands penis and the cavernous corpora is displaced by a megalourethra. In the Dillon (5) case, a cystic area was seen arising from the perineum.
Significant concomitant upper urinary tract abnormalities may be present in any patient with megalourethra, a fact that should lead to the routine investigation of the upper urinary tract in all patients with this developmental anomaly (1)

During pregnancy:
Termination of pregnancy can be offered before viability. Without other malformations and normal chromosomal study, sonographic monitoring of amniotic fluid index, urinary bladder volume, and fetal urine biochemistry and fetal serum beta 2-microglobulin (7) can be used to rule out severe renal impairment. Early decompression of severe bladder obstruction by vesico-amniotic shunt may prevent or attenuate these complications and improving the prognosis. Fetuses that develop mild urinary tract distension have better prognosis. Mild hydronephrosis and megalourethra may be the only manifestations in these cases. 
Neonatal period:
 Imperforated anus can be corrected on the first day. Vesicostomy can be considered early in life. A neonatal penile urethrostomy can be performed. Treatment of megalourethra follows the principles of surgery for hypospadias, with urethroplasty (Nesbit, Johansson, Heaton and others techniques). The surgical treatment of fusiform type of megalourethra involves the placement of penile prosthesis, in the adult period.

The prognosis depends on the degree of renal function compromise and severity of associated anomalies. Often, patients with fusiform megalourethras have associated lethal congenital malformations, and unfortunately fusiform megalourethra is usually an autopsy finding since this condition often is associated with stillbirths. Associated anomalies determine the prognosis of patients with scaphoid type, ultimately depend on renal damage.
Penis prosthesis can be considered in fusiform type during adult period.


1. Appel RA, Kaplan GW, Brock WA, Streit D. Megalourethra. J Urol. 1986 Apr;135(4):747-51.

2. Aqua K, McKurdy Ch, Reed K, Seeds JW. Prune-belly syndrome. 1994-02-03-21

3.  Ardiet E, Houfflin-Debarge V, Besson R, Subtil D, Puech F. Prenatal diagnosis of congenital megalourethra  associated with VACTERL sequence in twin pregnancy favorable postnatal outcome. Ultrasound Obstet Gynecol. 2003 Jun;21(6):619-20.

4. Cetinkursun S, Ozturk H, Sakarya MT, Surer L. Congenital megalourethra. Indian J Pediatr. 1996 Jul-Aug;63(4):566-8.

5. Dillon E, Rose PG, Scott JE. Case report: the antenatal ultrasound diagnosis of megalourethra. Clin Radiol. 1994 May;49(5):354-5.

6. Espinoza-Valverde F, Barrios-Rodriguez F, Hernandez-Bustillos, Rama E, López Huerta. Megalourethra escafoide congénita: reporte de un caso y revisión de la literatura. Rev Mex de Urología. 1999 Marzo-abril; 59 (2):81-83

7. Freedman AL, Bukowski TP, Smith CA, Evans MI, Berry SM, Gonzalez R, Johnson MP. The use of urinary B2 microglobulin to predict renal dysplasia in fetal obstructive uropathy. Fetal Diagnosis and Therapy 12 (1):1-6, 1997

8. Fernbach SK Urethral abnormalities in male neonates with VATER association. AJR Am J Roentgenol 1991 Jan;156(1):137-40

9. Fisk NM, Dhillon HK, Ellis CE, Nicolini U, Tannirandorn Y, Rodeck CH. Antenatal diagnosis of megalourethra in a fetus with the prune belly syndrome. J Clin Ultrasound. 1990 Feb;18(2):124-8.

10.  Fisk NM, Dhillon HK, Ellis CE, Nicolini U, Tannirandorn Y, Rodeck CH.  Antenatal diagnosis of megalourethra in a fetus with the prune belly syndrome. J Clin Ultrasound. 1990 Feb;18(2):124-8.

11. García de León JM, Chávez EG. Megauretra congénita Bol.Col.Mexicano de Urol. 2003 Enero-Marzo; 18 (1): 24-27

12.  Gokalp A, Gultekin EY. Megalourethra associated with prune-belly syndrome. Turk J Pediatr. 1993 Apr-Jun;35(2):

13. Katz G,Landau EH, Pode D. Congenital urethral stricture. Harefuah 1994;127(9):298-300.

14.  Krapp M, Geipel A, Germer U, Krokowski M, Gembruch U. First-trimester sonographic diagnosis of distal urethral atresia with megalourethra in VACTERL association. Prenat Diagn. 2002 May;22(5):422-4.

15.  Kirchner SG, Burko H. Congenital megalourethra. Pediatr Radiol. 1975 Mar 20;3(2):89-92.

16.  Kroovand RL, Al-Ansari RM, Perlmutter AD. Urethral and genital malformations in prune belly syndrome. J Urol. 1982 Jan;127(1):94-6. 

17.  Lam YH, Tang MH. Sonographic diagnosis of congenital megalourethra at 13 weeks of gestation. Ultrasound Obstet Gynecol. 2000 Nov;16(6):585-6.

18.  Lockhart JL, Reeve HR, Krueger RP, Glenn JF, Henry HH 2nd. Megalourethra.
Urology. 1978 Jul;12(1):51-4.

19.  Mandell J, Bromley B, Peters CA, Benacerraf BR. Prenatal sonographic detection of genital malformations.J Urol. 1995 Jun;153(6):1994-6.

20. Mortensen PH, Johnson HW, Coleman GU, Lirenman DS, Taylor G, McLoughlin MG.
 Megalourethra. J Urol. 1985 Aug;134(2):358-61.

21.  Nakayama DK, Harrison MR, Chinn DH, de Lorimier AA. The pathogenesis of prune belly. Am J Dis Child. 1984 Sep;138(9):834-6.

22.  Nesbitt TE. Congenital megalo-urethra. Postgrad Semin Am Urol Assoc North Cent. 1954;2:117-9.
23.  Nesbitt TE. Congenital megalourethra. J Urol. 1955 May;73(5):839-42. [PubMed - OLDMEDLINE for Pre1966]

24.  Perrotin F, Ayeva-Derman M, Lardy H, Cloarec S, Lansac J, Body G. Prenatal diagnosis and postnatal outcome of congenital megalourethra. Report of two cases. Fetal Diagn Ther. 2001 Mar-Apr;16(2):123-8. 

25.  Reinberg Y, Chelimsky G, Gonzalez R. Urethral atresia and the prune belly syndrome. Report of 6 cases. Br J Urol. 1993 Jul;72(1):112-4.

26.  Savanelli A, Schiano A, Esposito C, Russo S, Dolezalova H. Congenital megalourethra associated with urethral duplication and imperforate anus. Pediatr Surg Int. 1998 Oct;13(8):607-9.

27.  Seki N, Senoh K, Kubo S, Tsunoda T. Congenital megalourethra: a case report.
Int J Urol. 1998 Mar;5(2):191-3.

28. Silva S, Jeanty P, Prune-belly syndrome. 1999-05-11-16

29.  Simma B, GaBner I, Brezinka C, Ellemunter H, Kreczy A. Complete prenatal urinary tract obstruction caused by congenital megalourethra. J Clin Ultrasound. 1992 Mar Apr;20(3):197-9.

30.  Sepulveda W, Berry SM, Romero R, King ME, Johnson MP, Cotton DB. Prenatal diagnosis of congenital megalourethra. J Ultrasound Med. 1993 Dec;12(12):761-6. PMID:

31.  Sharma AK, Shekhawat NS, Agarwal R, Upadhyay A, Mendoza WX, Harjai MM.
 Megalourethra: a report of four cases and review of the literature. Pediatr Surg Int. 1997 Jul;12(5-6):458-60

32.  Smith DP, Felker RE, Noe HN, Emerson DS, Mercer B.  Prenatal diagnosis of genital anomalies.Urology. 1996 Jan;47(1):114-7.

33. Velhote CE, Ferreira RS, Franco de Oliveira T, Köenig W, Crivelenti D. Megauretra congênita: a propósito de dois casos. J Bras Urol 1991; 17:271-273

34.  Volmar KE, Nguyen TC, Holcroft CJ, Blakemore KJ, Hutchins GM. Phimosis as a cause of the prune belly syndrome: comparison to a more common pattern of proximal penile urethra obstruction. Virchows Arch. 2003 Feb;442(2):169-72. Epub 2002 Nov 30.

35.  Wakhlu AK, Wakhlu A, Tandon RK, Kureel SN.  Congenital megalourethra. J Pediatr Surg. 1996 Mar;31(3):441-3.

36.  Wu MH, Wu RC, Kuo PL, Huang KE. Prenatal ultrasonographic diagnosis of congenital megalourethra. Prenat Diagn. 1995 Aug;15(8):765-8.

37. Wu MH, Wu RC, Kuo PL, Huang KE. Prenatal ultrasonographic diagnosis of congenital megalourethra.Prenat Diagn. 1995 Aug;15(8):765-8.


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