What should you know about untreated kidney stones?

A kidney stone is a hard crystal that can move from the kidney into the ureter, the narrow tube leading to the bladder. Small stones may pass in urine, while a larger or awkwardly placed stone can obstruct flow. Flank pain, abdominal pain, painful urination or difficulty passing urine may occur, sometimes with nausea or blood in the urine. Ongoing blockage can impair kidney drainage. If infection is present behind an obstruction, the illness can become serious quickly. Dehydration may make urine more concentrated and can contribute to stone formation.

Arrange a GP consultation for persistent pain, urinary symptoms or a suspected stone. Assessment may include urine and blood tests and imaging such as an abdominal ultrasound; the choice depends on symptoms and clinical findings. Drink fluids normally unless a clinician has restricted your intake, and do not force large amounts while in severe pain or vomiting. Use only recommended pain relief, especially if you have kidney disease, stomach ulcers, are pregnant or take other medicines. A clinician may monitor passage, prescribe treatment or arrange a procedure.

Seek emergency care for fever or chills with flank pain, inability to pass urine, severe or worsening pain, repeated vomiting, fainting, confusion or feeling very unwell. These signs can indicate infection, significant obstruction or dehydration. Prompt assessment is also needed for a single kidney, pregnancy, known kidney disease or symptoms that do not settle. Do not wait for a stone to pass if urine flow has stopped or infection is suspected.

Ask: Where is the stone and is urine flow blocked? Do I need an abdominal ultrasound or another scan? Which pain medicines are suitable for me? What symptoms mean emergency care? How will we know the stone has passed? What can reduce my chance of another stone?