Megaureter

Classification according to ICD-10
Q62.1	Congenital ureteral stenosis
Q62.2	Congenital megaureter
N13.5	Ureteral stenosis
N28.8	Megaureter
ICD-10 online (WHO version 2019)

( Normal ureters are shown in this picture ) Ureters that are congenitally enlarged are known as megaureters.

A megaureter ( Syn. Megaloureter) , from ancient Greek μέγας megas , German 'large' and from Latin ureter , ancient Greek Ουρητήρας ouretéras , German 'ureter' , is an abnormally enlarged ureter with compensatory wall hypertrophy.

It can occur on one or both sides. The megaureter impresses with its massive expansion and mostly increased winding (as a sign of an increase in length).

Occurrence

Primary obstructive megaureters are more common on the left side, in males 4 times more often, in about 20% on both sides. The megaureter is the most common cause of upper urinary tract obstruction after ureteral obstruction . In. 26–40% have additional anomalies in the urinary tract.

Classification

Depending on the cause, a distinction is made between:

• Primary megaureter , a congenital malformation with the replacement of the smooth ureteral muscles by connective tissue, which leads to neuromuscular dyskinesia and thus to a large extent to a disruption of the physiological peristalsis .
• Secondary megaureter
  • Acquired prenatally due to other congenital diseases such as urethral valve , prune belly syndrome or neurogenic bladder often with (urorenal) kidney dysplasia
  • Ureter enlargement acquired after birth (syn. ureter dilatation), known as hydroureter . The cause of this is an accumulation of urine z. B. due to stone, stricture , inflammation , bladder wall hypertrophy, tumors or VUR ( upper urinary tract obstruction )

Different types of megaureter

A distinction can be made between the following types:

• Obstructive megaureter : enlargement of the ureter through a narrowing at its mouth in the urinary bladder. Synonyms are: ureteral stenosis (UMS); Distal ureteral stenosis; prevesical ureteral stenosis; terminal ureteral stenosis; deep ureteral stenosis; Ureteral stenosis This obstruction can damage the kidneys over time. Sometimes this obstruction heals on its own, but precise follow-up observations and examinations are imperative.
  • Primarily obstructive mostly due to a distal, adynamic ureter segment, rarely due to a real stenosis or ureter valve, often with spontaneous remission in up to (85%)
  • Secondary in the case of functional flow obstruction with increased bladder pressure (urethral valves, neurogenic bladder)
• Refluxive megaureter :
  • Primarily refluxive The reason for this type of megaureter is the VUR with backflow of urine from the bladder into the kidneys. This megaureter is also often associated with megazystis-megaureter syndrome , a condition in which the bladder does not empty completely and the ureter is enlarged because urine "shuttles" between the bladder and kidneys (vesicoureterorenal reflux)
  • Secondary refluxing in the case of obstruction of the drainage with increased bladder pressure (urethral valves, neurogenic bladder), if the bladder pressure can no longer be compensated by the closure mechanism at the ostium
• Obstructive, refluxive megaureter : This is an obstructed ureter that is affected by VUR.
• Non-obstructive, non-refluxing megaureters : These are megaureters that are not caused by obstruction or reflux of urine.
  • Primarily not obstructive, not refluxive, “idiopathic”, as a diagnosis of exclusion . Most of these megaureters heal over time.
  • Secondary non-obstructive, non-refluxive in diabetes insipidus with excessively high flow rates or in atony of the ureter as a result of a ( gram-negative ) urinary tract infection

A megaureter can cause urinary congestion and vesicorenal reflux (VUR) as well as (urorenal) renal dysplasia .

classification

The following Pfister and Hendren classification is used for the extent of the expansion of the upper urinary tract:

• Type I only dilated distal ureter
• Type II also enlarged renal pelvis
• Type III additionally enlarged calyxes, ureter clearly tortuous.

diagnosis

Today, most megaureters are already diagnosed during prenatal diagnosis .

The prenatal ultrasound then shows a urinary tract disorder in the fetus. Since the Megaureter can cause urinary tract infections or an obstruction of the kidneys, which over time leads to kidney damage, precise diagnostics and close monitoring are necessary.

A ureter more than 6 mm thick is considered pathological.

In addition, other imaging methods can be used, such as the excretory urogram , micturition cystourethrogram or micturition urosonogram with the question of a VUR, magnetic resonance tomography or kidney scintigraphy to determine the laterally separated kidney function.

therapy

If the examinations show an obstruction or impaired kidney function, surgical treatment is indicated. The typical operation to correct the megaureter is re-implantation of the ureters.

Usually, the operation is not performed before the child is one year old, unless the child is already showing signs of deterioration in kidney function or febrile urinary tract infections develop.

Children with a megaureter need antibiotic prophylaxis during the period of observation, i. H. up to the point in time at which the megaureter either heals itself or until the point in time at which the surgical treatment takes place. The operation consists of an enlarged groin incision over which a new ureter is implanted. This is either extravesical, i.e. H. without opening the urinary bladder, or transvesically, i.e. by opening the urinary bladder. If there is an obstruction, it is removed.

The ureter enlargement often persists after the operation, so it may be necessary to check the success of the operation. To do this, it may be necessary to perform another micturition cysturethrography or urosonography and kidney scintigraphy. A new obstruction can recur in about 5% of cases.

literature

• C. Taube, Inaugural dissertation 2017
• M.-K. Farrugia, R. Hitchcock, et al. a .: British Association of Pediatric Urologists consensus statement on the management of the primary obstructive megaureter. In: Journal of Pediatric Urology. 10, 2014, p. 26
• W. Schuster, D. Färber (editor): Children's radiology. Imaging diagnostics. , P. 696, 5.2.5, Springer 1996, ISBN 3-540-60224-0 .
• Marcel Bettex (ed.), Max Grob (introductory), D. Berger (editing), N. Genton, M. Stockmann: Pediatric Surgery. Diagnostics, indication, therapy, prognosis. 2nd, revised edition, pp. 8.91 and 8.126, Thieme, Stuttgart / New York 1982, ISBN 3-13-338102-4

Individual evidence

1. ↑ Willibald Pschyrembel : Clinical Dictionary , 266th, updated edition, de Gruyter, Berlin 2014, ISBN 978-3-11-033997-0 , keyword: “Megaureter”
2. ↑ ^{a b c} emedicine
3. ↑ JW Thüroff, H. Schulte-Wissermann (editor): Pediatric urology in clinic and practice. , 2nd edition, 2000, p. 213, Thieme, ISBN 3-13-674802-6
4. ^ W. Pschyrembel: Clinical dictionary. de Gruyter, Berlin 1977, ISBN 3-11-007018-9 .
5. ^ Roche Lexicon Medicine (online): Mega | ureter. (on-line)
6. ↑ Megaureter, congenital primary. In: Orphanet (Rare Disease Database).
7. ^ Roche Lexicon Medicine (online): Hydro | ureter. (on-line)
8. ↑ 5.3.2. European Association of Urology GUIDELINES ON PAEDIATRIC UROLOGY
9. ↑ A. Sigel: Urinary obstruction in childhood. In: A. Sigel, R.-H. Ringert (Ed.): Pediatric urology. 2nd edition, Springer, Berlin 2001, ISBN 3-662-08081-8 (print) / ISBN 978-3-662-08080-1 (e-book), p. 118.
10. ^ RC Pfister, WH Hendren: Primary megaureter in children and adults. Clinical and pathophysiologic features of 150 ureters. In: Urology. Volume 12, Number 2, August 1978, pp. 160-176, doi : 10.1016 / 0090-4295 (78) 90327-8 , PMID 695145 .
11. ^ EJ Kass: Megaureter. In: PP Kelalis, R. King, AB Belman (Eds.): Clinical Pediatric Urology. 1992, Saunders Philadelphia, pp. 781-821
12. ↑ Uptodate
13. ↑ D. Manski: www.urologielehrbuch.de http://www.urologielehrbuch.de/megaureter.html

Web links

• Radiopaedia

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