Follow-up of Ureteral Stones <9 mm: Clinical Implications of Persistent Symptoms

Aim

To study patients presenting to the emergency department with acute renal colic to determine whether resolution of hydronephrosis and pain accurately predicts stone passage on follow-up CT.

Materials and methods

This is a secondary analysis of a multicenter prospective randomized clinical trial of patients diagnosed by computed tomography (CT) with a symptomatic ureteral stone <9 mm in diameter.

Participants were followed after randomization to assess analgesic use and to assess stone clearance and hydronephrosis on a repeat CT scan obtained at 29-36 days.

Results

Four hundred and three patients were randomized in the original study and patients were included in this analysis if they did not undergo stone removal surgery and had a CT scan and analgesic information at follow-up (N = 220).

Hydronephrosis was detected in 181 (82%) on initial CT. At follow-up CT, 43 (20%) participants had a persistent ureteral stone. Of these patients, 36 (84%) had no pain, 26 (60%) had no hydronephrosis, and 23 (53%) had no pain or hydronephrosis.

Resolution of hydronephrosis was associated with stone passage (RR 4.6, 95% CI 1.9, 11.0), whereas resolution of pain was not (RR 1.1, 95% CI 0. 9, 1,4).

Conclusion

In patients with urinary stones, stone passage is associated with resolution of hydronephrosis but not with resolution of pain.
In patients with persistent ureteral stones, neither pain nor hydronephrosis are always present.
These findings have important implications in the imaging follow-up of patients with urinary stones.

Comments

Follow-up of ureteral stones smaller than 9 mm

At 1 month, 20% of patients had persistent ureteral stones; About half of them had neither hydronephrosis nor pain.

In a recent study of patients presenting with painful ureteral stones, cessation of pain over the following weeks did not necessarily mean that the stone had disappeared (NEJM JW Gen Med June 1, 2018 and J Urol 2018;199:1011).

Now, in another study, researchers examined this problem in 220 patients with acute ureteral colic (stone diameter, <9 mm) who did not undergo urologic intervention to remove the stone.

The stones were documented by computed tomography (CT); Hydronephrosis was present in 81% of cases.

At follow-up CT approximately 1 month later, 80% of patients had passed stones and 20% had persistent stones. Among the 43 patients with persistent stones, 36 had no pain, 26 had no hydronephrosis, and 23 had neither hydronephrosis nor pain.

Even among patients with stones smaller than 5 mm, stones persisted in 11%, and half of those patients had no hydronephrosis or pain.

This study provides additional evidence that resolution of pain does not rule out the persistence of a ureteral stone.

Furthermore, it shows that hydronephrosis is not always present with persistent stones; This latter finding suggests that follow-up imaging with renal ultrasound (which is sensitive for detecting hydronephrosis but not for visualizing ureteral stones) would miss some persistent ureteral stones.

For patients who become asymptomatic but do not recover a stone, we currently have no consensus on the optimal imaging strategy; however, all of these patients clearly require follow-up.

Follow-up of Ureteral Stones <9 mm: Clinical Implications of Persistent Symptoms

Resolution of pain does not reliably indicate the absence of a ureteral stone <9 mm, underscoring the importance of follow-up imaging studies to confirm stone clearance and prevent potential complications associated with residual stones.