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Fetal and Congenital Megacystis
Definition:
Congenital megacystis is an enlarged bladder with massive vesicoureteral reflux of various etiology. In the first trimester, fetal megacystis is most commonly defined as a longitudinal bladder dimension of over 7 mm. Later in pregnancy, megacystis refers to a sagittal bladder diameter (in mm) greater than gestational age (in weeks) + 12 (Taghavi et al., 2017).Epidemiology:
The prevalence of megacystis is around 1:1500 in the first trimenon.
Etiology:
Many syndromes and diseases lead to megacystis:
- With lower urinary tract obstruction (LUTO): urethral valves (60%), stenosis or atresia.
- Vesicoureteral reflux: voiding leads to reflux into the ureters, ureteral distension and gradual increase in bladder capacity. Since not every patient with vesicoureteral reflux develops megacystis, co-factors play a role in bladder distension; see the following diseases.
- Congenital megacystis with the microcolon-intestinal hypoperistalsis-syndrome (MMIHS) (Berdon syndrome). MMIHS is a form of familial visceral myopathy, other manifestations (often with megacystis) are megaduodenum or megacystis-megaureter-syndrome.
- Syndromes: prune-belly-syndrome, Trisomia (13, 18 or 21), caudal regression syndrome.
Prognose:
Oligohydramnios, lung hypoplasia, and intestinal obstruction confer a poor prognosis.
Treatment:
See treatment of vesicourethral reflux and posterior urethral valves.
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References
Mandell, J.; Lebowitz, R. L.; Peters, C. A.; Estroff, J. A.; Retik, A. B. & Benacerraf, B. R.
Prenatal diagnosis of the megacystis-megaureter association.
J Urol, 1992, 148, 1487-1489
Puri, P. & Shinkai, M.
Megacystis microcolon intestinal hypoperistalsis syndrome.
Semin Pediatr Surg, 2005, 14, 58-63
K. Taghavi, C. Sharpe, and M. D. Stringer, “Fetal megacystis: A systematic review.,” J. Pediatr Urol, vol. 13, no. 1, pp. 7–15, 2017.
Deutsche Version: Megazystis