[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) › Renal pelvis [Urinary system](https://durgical.com/en/anatomy/system/urinary-system/) · [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) # Renal pelvis The renal pelvis is the funnel inside each kidney that collects urine and passes it to the ureter; kidney stones often lodge where it narrows. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=abdomen&select=renal_pelvis&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The funnel inside each kidney that collects urine from the calyces and narrows into the ureter. ## What it does Collects urine. Most stones form here or in the calyces. ## Key points - Pelviureteric junction: the first of three narrowings of the ureter where stones lodge; the others are the crossing of the iliac vessels at the pelvic brim and the vesicoureteric junction (the narrowest) - Most posterior hilar structure, so it can be reached from behind without crossing the main vessels - A lower-pole artery crossing in front of the pelviureteric junction is a classic cause of obstruction in older children and adults ## Key facts **Where** Funnel in renal sinus at the hilum, most posterior of hilar structures (vein, artery, pelvis front to back) **Function** Collects urine and funnels it into the ureter by peristalsis **Drains** Minor calyces (about 7–14) into 2–3 major calyces **Into** Ureter at pelviureteric junction, a narrowing where stones lodge ## Relations **In front** Renal vein and the anterior division of the [renal artery](https://durgical.com/en/anatomy/renal-artery/) with its segmental branches **Behind** Posterior segmental artery, which crosses behind the [pelvis](https://durgical.com/en/anatomy/region/pelvis/) to the back of the [kidney](https://durgical.com/en/anatomy/kidney/) (the exception to VAP); then [psoas major](https://durgical.com/en/anatomy/psoas-major/) **Below** Narrows at the pelviureteric junction into the [ureter](https://durgical.com/en/anatomy/ureter/), which runs down on psoas major ## How to find it The hilum, where the pelvis leaves the kidney, lies near the transpyloric plane from the front and at the level of the first lumbar spinous process from behind, a few centimetres from the midline. As the most posterior hilar structure it is approached from behind in pyeloplasty and percutaneous nephrolithotomy, usually through a posterior calyx. ## On imaging On ultrasound a dilated, fluid-filled pelvis with dilated calyces means hydronephrosis; an extrarenal pelvis can look similar without calyceal dilatation. CT urography opacifies the pelvicalyceal system in the excretory phase and shows filling defects (stones, clots, urothelial tumours). Non-contrast CT is the usual test for stones. ## Common problems - Kidney stones; a blockage at its outlet (UPJ obstruction). ## How it is diagnosed Blood (creatinine) and urine tests; ultrasound; CT. ## Treatment - Control blood pressure and diabetes; treat infections; dialysis or a kidney transplant for kidney failure. ## Clinical notes - A stone stuck at the pelviureteric junction causes renal colic, loin pain spreading to the groin, from stretch of the pelvis and ureter - A staghorn calculus fills the pelvis and branches into the calyces; it is linked to infection - Urothelial (transitional cell) carcinoma can arise in the pelvis, with the same lining as the bladder - Pyeloplasty rebuilds an obstructed pelviureteric junction; when a vessel crosses it, the new junction is placed in front of the vessel ## Anatomical variants - Extrarenal pelvis, lying mostly outside the renal sinus - Bifid pelvis or full duplex system, from early splitting of the ureteric bud ## Development The tip of the ureteric bud widens into the pelvis, and its branches form the major and minor calyces and the collecting ducts. ## Memory aid Renal hilum from front to back: VAP – Vein, Artery, Pelvis. ## Related conditions - [Kidney stones (urolithiasis)](https://durgical.com/en/conditions/kidney-stones/) - [Acute pyelonephritis](https://durgical.com/en/conditions/acute-pyelonephritis/) - [Acute kidney injury](https://durgical.com/en/conditions/acute-kidney-injury/) - [Autosomal dominant polycystic kidney disease](https://durgical.com/en/conditions/autosomal-dominant-polycystic-kidney-disease/) - [Cystinuria](https://durgical.com/en/conditions/cystinuria/) - [Hydronephrosis and obstructive uropathy](https://durgical.com/en/conditions/hydronephrosis-and-obstructive-uropathy/) - [Renal papillary necrosis](https://durgical.com/en/conditions/renal-papillary-necrosis/) - [Medullary sponge kidney and medullary cystic disease](https://durgical.com/en/conditions/medullary-sponge-kidney-and-medullary-cystic-disease/) ## Test yourself Think of the answer, then tap the question to see it. ## Where does the renal pelvis lie among the hilar structures? It is the most posterior (vein, artery, pelvis from front to back), so it can be reached from behind without crossing the main vessels. ## What are the three narrowings of the ureter where stones lodge? The pelviureteric junction, the crossing of the iliac vessels at the pelvic brim, and the vesicoureteric junction, which is the narrowest. ## What is a classic cause of pelviureteric junction obstruction in older children and adults? A lower-pole artery crossing in front of the junction; at pyeloplasty the new junction is placed in front of the vessel. ## What is a staghorn calculus? A stone that fills the renal pelvis and branches into the calyces; it is linked to infection. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/renal-pelvis/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** pelvis renalis TA2 3384 **Official Spanish (DeCS)** Pelvis renal DeCS D007682 **English (TA2)** Renal pelvis **Also called** kidney pelvis · typus dendriticus · branching type ## Related - [Kidneys](https://durgical.com/en/anatomy/kidney/) - [Ureters](https://durgical.com/en/anatomy/ureter/) - [Right renal artery](https://durgical.com/en/anatomy/renal-artery-abdomen/) - [Left renal artery](https://durgical.com/en/anatomy/renal-artery/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=7857&filter=ths_termall&q=Pelvis%20Renal); [Anatomy, Abdomen and Pelvis: Kidneys](https://www.ncbi.nlm.nih.gov/books/NBK482385/); Anatomy of the Human Body (20th ed.): Surface Markings of the Abdomen (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain; [25.3 Gross Anatomy of the Kidney](https://openstax.org/books/anatomy-and-physiology-2e/pages/25-3-gross-anatomy-of-the-kidney) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/renal-pelvis/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/renal-pelvis/