Stages of Passing a Kidney Stone: Complete Timeline from Kidney to Toilet
- The 5 stages of stone passage (anatomical journey)
- Stage 1: Stone detachment in the kidney
- Stage 2: Ureteropelvic junction obstruction
- Stage 3: Mid‑ureteral travel
- Stage 4: Ureterovesical junction (the final pinch)
- Stage 5: Bladder and expulsion
- Typical timeline by stone size
- Interactive FAQ – 9 common questions
The 5 stages of stone passage (anatomical journey)
A kidney stone does not simply fall out. It travels through a narrow, muscular tube called the ureter (about 25‑30 cm long, 2‑4 mm wide). The journey has five distinct anatomical stages, each with characteristic symptoms and durations. Understanding these stages helps you know where the stone is and whether you need medical intervention.
For stones <5mm, the entire journey typically takes 2‑4 weeks. For 5‑6mm stones, 4‑6 weeks. Stones >6mm often get stuck permanently and require surgery.
Stage 1: Stone detachment in the kidney
What happens: A stone that was sitting harmlessly in a kidney calyx (a cup‑like drainage area) breaks loose and falls into the renal pelvis, the funnel‑shaped collecting area before the ureter.
Symptoms: Often none initially. Some patients feel a dull ache in the flank or notice blood in urine (microscopic or visible). This stage may last days or weeks – the stone can sit in the renal pelvis without causing obstruction.
What to do: Increase water intake. No emergency. If you have an asymptomatic stone in the kidney, you may never know when it detaches.
Stage 2: Ureteropelvic junction (UPJ) obstruction
What happens: The stone enters the ureter at its narrowest point (2‑3 mm). This is where most patients experience their first severe pain – renal colic.
Symptoms: Sudden, severe flank pain that comes in waves (20‑60 minutes). Pain may radiate to the lower abdomen or groin. Nausea, vomiting, and sweating are common. Urine may be pink or bloody.
Duration: Hours to days. If the stone passes this narrow point, pain may subside temporarily. If stuck for >48 hours with hydronephrosis, intervention is needed.
Stage 3: Mid‑ureteral travel
What happens: Once past the UPJ, the stone travels down the mid‑ureter, which is slightly wider (3‑4 mm). The stone may move in fits and starts, causing intermittent pain.
Symptoms: Colicky pain that comes and goes. Pain may shift from flank to lower abdomen or groin as the stone descends. Some patients have pain only when the stone moves; they may feel fine between episodes.
Duration: Days to 2 weeks. Stones often pause at the pelvic brim, where the ureter crosses the iliac vessels.
What to do: Continue high fluid intake (3 litres/day). Tamsulosin (if prescribed) relaxes the ureter and speeds passage. Strain all urine to catch the stone.
Stage 4: Ureterovesical junction (UVJ) – the final pinch
What happens: The stone reaches the narrowest point again (2‑3 mm) where the ureter enters the bladder. This is the most common site for stones to get stuck. Once past the UVJ, the stone falls into the bladder.
Symptoms: Intense suprapubic (lower abdominal) pain, severe urgency to urinate, pain at the tip of the penis or labia. Patients often feel like they need to void constantly but only produce small amounts. This can be mistaken for a urinary tract infection.
Duration: Hours to several days. Once the stone passes into the bladder, pain stops abruptly.
Stage 5: Bladder and expulsion
What happens: The stone floats in the bladder. The urethra is much wider (8‑9 mm), so stones up to 8‑10 mm can pass easily once in the bladder. You may not even feel it exit.
Symptoms: No pain. Some patients feel a momentary pinch at the urethral opening. You may hear a “plink” sound in the toilet or see a small stone.
Duration: Minutes to a few days. The stone usually passes with the first strong stream after entering the bladder.
What to do: Strain urine until you confirm passage. Save the stone for analysis – this is critical for prevention.
Typical timeline by stone size
Based on 2025 data from 5,000+ patients:
| Stone size | Typical total passage time | Most likely to get stuck at |
|---|---|---|
| 1‑3 mm | 1‑7 days | Usually passes without noticeable pain |
| 4‑5 mm | 7‑21 days | UPJ or UVJ; may cause several colic episodes |
| 6‑7 mm | 21‑42 days (if at all) | UVJ – only 30‑40% pass spontaneously |
| 8‑10 mm | Unlikely to pass | Usually gets stuck at UPJ or UVJ; needs surgery |
Interactive FAQ – Stages of passing a kidney stone
Pain location gives clues: flank pain suggests UPJ or upper ureter. Lower abdominal/groin pain suggests mid‑ureter or UVJ. Sudden relief suggests bladder entry. CT scan is the only definitive way.
The ureter contracts in peristaltic waves to push urine. When a stone blocks the ureter, each contraction causes a pressure spike – hence waves of pain lasting 20‑60 minutes. Between waves, the ureter relaxes and pain subsides.
Yes. If a stone does not pass within 6‑8 weeks, it is considered chronically impacted. It will not pass spontaneously and may become embedded in the ureteral wall. Surgical removal is required.
If you have manageable pain and no fever or hydronephrosis, you can wait 2‑4 weeks for stones <6mm. If pain is severe or stone does not move on repeat imaging after 2 weeks, proceed to URS.
Yes. High urine flow increases hydrostatic pressure above the stone, helping push it down. Drink 3 litres daily. Do not restrict fluids even if you have pain.
Not directly. You feel pain from ureteral spasm and obstruction, not the stone itself. When the stone moves past a narrow point, pain may change location or intensity.
It can cause hydronephrosis (kidney swelling) and eventually kidney damage. Even without severe pain, a stone at UVJ for >6 weeks should be removed.
Yes. Hematuria (visible or microscopic) is common as the stone irritates the ureteral lining. However, heavy bleeding with clots is not normal – seek care.
Usually within 24 hours. Some stones may take 2‑3 days. You can help by drinking extra water and urinating with a strong stream.
Disclaimer: The stages described are typical but individual experiences vary. If your pain becomes unbearable, you develop fever, or cannot urinate, go to Vivekananda Hospital emergency immediately.