The ureter serves as a connecting muscular tube between the renal pelvis and the urinary bladder to transport urine. Abdominal or flank pain, urinary retention, and fever are signs that the ureter is not functioning properly.
What is the ureter?
Schematic diagram showing the anatomy and structure of the urinary bladder. Click to enlarge. The ureter, or ureter, is a paired muscular-tubular hollow organ that is approximately 25 to 30 cm long and about 4 to 7 mm in diameter, connecting the respective renal pelvis (pelvis renalis) to the urinary bladder. Radiologically, the hollow organ can be divided into an upper section extending from the renal pelvis to the upper edge of the sacrum (Os sacrum), a middle section extending to the lower end of the Os sacrum, and a lower section of the ureter, which subsequently merges into the urinary bladder. In its course through the abdomen and pelvic cavity, the ureter passes through three physiologic strictures, in the area of which renal or ureteral stones or inflammation predominantly manifest.
Anatomy and structure
The ureter runs behind the abdomen along the internal muscles of the back into the pelvic cavity, where it opens from behind into the urinary bladder. In cross-section, the ureter has the characteristic structure of a membranous muscular tube. The innermost layer is the so-called tunica mucosa (also mucosa or mucosal layer), the middle layer is the tunica muscularis, a muscular layer of smooth muscle, while the outermost layer, the tunica adventitia, as a connective tissue anchoring layer, links the ureter with the surrounding structures. The ureter has physiological constrictions in three areas. These are located in the funnel-shaped transition from the pelvis renalis into the ureter, at the crossing of the ureter with the iliac or pelvic artery (Arteria iliaca communis) and in the uretero-vesical transition (Ostium ureteris), where the ureter opens obliquely into the urinary bladder. As a result, it can be compressed and closed by the muscles of the urinary bladder, preventing urine from flowing back into the ureter.
Functions and tasks
The main function of the ureter is to transport urine or urine from the paired renal pelvises to the urinary bladder. In this process, the smooth muscles of the tunica muscularis can contract successively during transport (peristalsis), thus ensuring that the urinary fluid is also transported against the gradient toward the urinary bladder by the resulting peristaltic wave, similar to an assembly line. This peristaltic wave is generated once to four times a minute by the muscles of the ureter and also serves to constantly self-clean the lumen in the hollow organ. In addition, the ureter still extends for a short section between the muscular layers of the urinary bladder, as it does not have a closure mechanism itself. During bladder emptying, the muscle layers of the urinary bladder contract and at the same time automatically close the entrance to the ureter, so that urine cannot flow back (reflux) and cause bladder and renal pelvic inflammation. In addition, cramp- or contraction-like muscle contractions (colic) attempt to remove debris (e.g., kidney stones) stuck at the constrictions from the ureter.
Diseases
The ureter often has malformations that lead to impaired urine transport or reflux. These, in turn, can cause hydroureter (ureteral dilation), recurrent infections such as acute or chronic pyelonephritis (inflammation of the renal pelvis) , kidney or urinary stone formation, and renal insufficiency. If there is a permanent reflux of urine from the urinary bladder into the ureter, repeated inflammations of the ureter as well as of the renal pelvis and the urinary bladder may manifest. Chronic inflammation may also cause formation of grayish-white plaques in the ureteral wall (malacoplakia) or ureteritis cystica (inflammation with vesicular mucosal flare-ups). Bacterially induced urinary tract inflammation (including coliform bacteria) can also cause malakoplakia. The most common disorders are ureteral outlet stenosis, ureterocele (spherical ureteral dilation), ureteral ectopy, a disturbed vesicoureteral junction as well as ureter duplex and ureter fissus.Megaureters (congenital ureteral dilatation), retroiliac or retrocaval ureters, ureteral diverticula (protrusions), ureteral stenoses (ureteral strictures), ureteral valves (ureters with mucosal folds) or an extrarenal calyx system, on the other hand, are rare malformations of the ureter. In extremely few cases, the cells of the layers lining the ureter may degenerate and lead to manifestation of benign or malignant ureteral tumors. Equally rare are traumatic ureteral injuries caused by penetrating abdominal injuries (gunshot, stab wounds). Iatrogenically caused injuries as well as deposits may cause ureteral stricture. Retroperitoneal fibrosis is etiologically unexplained, resulting in proliferation of connective tissue and impairment of the ureter.
Typical and common diseases
- Urinary retention
- Frequent urination
- Low urination
- Ureteral stone
- Urethritis (inflammation of the urethra)
- Incontinence (urinary incontinence)
