Sudden onset of severe pain in the flank is most often due to the passage of a stone formed in the kidney, down through the ureter. The pain is characteristically of very sudden onset, is colicky in nature (waves of increasing severity are followed by a reduction in severity, but it seldom goes away completely), and it radiates to the groin as the stone passes into the lower ureter. The pain may change in location, from the flank to the groin, but the location of the pain does not provide a good indication of the position of the stone, except in those cases where the patient has pain or discomfort in the penis and a strong desire to void, which suggest that the stone may have moved into the intramural part of the ureter. The patient cannot get comfortable, and may roll around in agony. Indeed, the majority of women we have seen with radiologically confirmed ureteric stones and who have also had children, describe the pain of a ureteric stone as being worse than the pain of labour.

The problem with these classic symptoms of ureteric colic is that approximately 50% of patients with the symptoms we have just described do not have a stone con.rmed on subsequent imaging studies, nor do they physically ever pass a stone (Smith et al. 1996, Thomson et al. 2001). They have some other cause for their pain. The list of differential diagnoses is very long. A sample of those that we have personally seen include leaking abdominal aortic aneurysms, pneumonia, myocardial infarction, ovarian pathology (e.g., twisted ovarian cyst), acute appendicitis, testicular torsion, in.ammatory bowel disease (Crohn’s, ulcerative colitis), diverticulitis, ectopic pregnancy, burst peptic ulcer, bowel obstruction, and malaria (presenting as bilateral loin pain and dark haematuria—black water fever)!

The point, then, in making a diagnosis is to exclude other causes of flank pain, many of which are serious and may be lifethreatening (leaking aortic aneurysm, gastrointestinal causes, medical causes), from those cases where the pain is due to a ureteric stone, which is very rarely life-threatening. Age of the patient can help in determining whether a diagnosis of a ureteric stone is more or less likely. Ureteric colic tends to be a disease of men (and to a lesser extent women) between the ages of roughly 20 and 60. It does affect younger and older patients, but the range of differential diagnoses at the extremes of age, and in women, is greater. Thus, a 25-year-old man who presents with sudden onset of severe, colicky flank pain probably has a ureteric stone, but an 80-year-old woman probably has something else going on.

Examination and Simple Tests

The pain from a ureteric stone is colicky in nature. It makes the patient want to move around, in an attempt to .nd a comfortable position. The patient may be doubled-up with pain. On the other hand, patients with conditions causing peritonitis, such as appendicitis or a ruptured ectopic pregnancy, want to lie very still. Any movement is very painful and in particular they do not like palpation of their abdomen. Thus, when you approach patients, just spend a few seconds looking at them. If they are lying very still, you may be dealing with a non-stone cause of flank pain.

Pregnancy Test

All premenopausal women with acute flank pain should undergo a pregnancy test. If this is positive, they are referred to a gynaecologist. If it is negative, they should undergo imaging to determine whether or not they have a ureteric stone. It goes without saying that any premenopausal woman who is going to undergo imaging using ionising radiation, should have a pregnancy test done .rst.

Dipstick or Microscopic Haematuria

While many patients with ureteric stones have dipstick or microscopic haematuria (and more rarely macroscopic haematuria), 10% to 30% of such patients have no blood in their urine (Kobayashi et al. 2003, Luchs et al. 2002). There is evidence that if a stone has been present in the ureter for 3 to 4 days, there is a greater likelihood that haematuria will not be detectable. The sensitivity of dipstick haematuria for detecting ureteric stones presenting acutely is in the order of 95% on the .rst day of pain, 85% on the second day of pain, and 65% on the third and fourth days (Kobayashi et al. 2003). Dipstick testing is slightly more sensitive than urine microscopy for detecting stones (80% versus 70%), and both ways of detecting haematuria have roughly the same speci.city for diagnosing ureteric stones (about 60%). The slightly greater sensitivity of dipstick testing over microscopy reflects the fact that seeing red blood cells depends on how good the technician is at looking for them, and that they lyse, and therefore disappear, if the urine specimen is not examined under the microscope within a few hours. Thus, if you see a patient with a history suggestive of ureteric colic, and their pain started 3 to 4 days ago, they may well have no blood detectable in their urine even though they do have a stone.

The relatively poor speci.city of dipstick or microscopic haematuria for detecting ureteric stones re.ects the multiple other pathologies that can mimic the pain of a ureteric calculus combined with the fact that blood is detectable in a proportion of patients without demonstrable urinary tract pathology; in fact, no abnormality is found in approximately 70% of patients with microscopic haematuria, despite full investigation with cystoscopy, renal ultrasound, and intravenous urography (IVU) (Khadra 2000). Thus, blood in the urine may be a completely coincidental .nding in a patient who presents with flank pain due to a non-stone cause.

Temperature

Perhaps the most important aspect of examination in patients with a ureteric stone confirmed on imaging is to measure their temperature. If patients have a stone, and they have a fever of, say, 39°C, they may well have infection proximal to the obstructing stone. A fever in the presence of an obstructing stone is an indication for urine and blood culture, intravenous fluids and antibiotics, and nephrostomy drainage if the fever does not resolve within a matter of hours of commencement of antibiotics.

Investigation of Suspected Ureteric Colic

The intravenous urogram (IVU) was for many years the mainstay of diagnostic imaging in patients with flank pain The last few years have seen a move toward computed tomography (CT) urography (CTU) CTU has the following advantages over IVU:

1. It has greater speci.city (95%) and sensitivity (97%) for diagnosing ureteric stones than has IVU (Smith et al. 1996). CTU can identify other, non-stone causes of flank pain such as leaking aortic aneurysms

2. There is no need for contrast administration with CTU. This avoids the chance of a contrast reaction. The risk of fatal anaphylaxis following the administration of low-osmolality contrast media for IVU is on the order of 1 in 100,000 (Caro et al. 1991).

3. CTU is faster, taking just a few minutes to image the kidneys and ureters. An IVU, particularly where delayed .lms are required to identify a stone causing high-grade obstruction, may take hours to identify the precise location of the obstructing stone

4. In some hospitals, where high volumes of CT scans are done, the cost of CTU is equivalent to that of IVU (Thomson et al. 2001).

If you only have access to IVU, remember that it is contraindicated in patients with a history of previous contrast reactions, and should be avoided in those with hay fever or a strong history of allergies or asthma who have not been pretreated with highdose steroids 24 hour before the IVU. Patients taking metformin for diabetes should stop this for 48 hours prior to an IVU. Clearly, being able to perform an alternative test in such patients, such as CTU, is very useful.

In hospitals where 24-hour access to CTU is not possible, patients with suspected ureteric colic may be admitted for pain relief, and undergo a CTU the following morning. It is our policy, when CT urography is not immediately available (between the hours of midnight and 8 a.m.), to perform an abdominal ultrasound in all patients over the age of 50 years who present with flank pain suggestive of a possible stone. This is done to exclude serious pathology such as a leaking abdominal aortic aneurysm and to demonstrate any other gross abnormalities due to non– stone-associated flank pain.

Plain abdominal x-ray and renal ultrasound are not suffi- ciently sensitive or speci.c for their routine use for diagnosing stones.

Magnetic Resonance Urography

This is a very accurate way of determining whether or not a stone is present in the ureter (Louca et al. 1999; O’Malley 1997). However, at the present time, cost and resticted availability limit its usefulness as a routine diagnostic method of imaging in cases of acute flank pain. This may change as MR scanners become more widely available.

Acute Management of Ureteric Stones

The management of any acutely presenting ureteric stone starts with pain relief. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as diclofenac (Voltarol) given by intramuscular or intravenous injection, by mouth, or per rectum can, in many cases, provide rapid and effective pain control (Laerum et al. 1996). In other cases opiate analgesics such as pethidine or morphine are required, in addition to NSAIDs.

There is no need to encourage the patient to drink copious amounts of fluids or to give them large volumes of .uids intravenously, in the hope that this will ‘.ush’ the stone out. Renal blood .ow and urine output from the affected kidney will tend to fall during an episode of acute partial obstruction due to a stone, and any excess .uid that is excreted will tend to cause a greater degree of hydronephrosis in the affected kidney, which will make ureteric peristalsis even less ef.cient than it already is. Remember, peristalsis, the forward propulsion of a bolus of urine down the ureter, can occur only if the walls of the ureter above the bolus of urine can coapt, i.e., close .rmly together. If they cannot, as occurs in a ureter distended with urine, the bolus of urine cannot move distally. This is why insertion of a percutaneous nephrostomy tube can restore ef.cient peristalsis. By draining the hydronephrosis and hydroureter, it allows the ureteric wall to coapt and thus encourages a return to normal peristaltic function.

In many instances, small ureteric stones pass spontaneously given a period of ‘watchful waiting’ with analgesic supplements for exacerbations of pain. Accurate determination of stone size (on plain abdominal x-ray if the stone is so visible or by CTU) can help predict the chances that the stone will pass out of the ureter and into the bladder; 95% of stones measuring 5mm or less pass spontaneously (Segura et al. 1997). However, it never ceases to amaze us that stones much larger than 5mm do, from time to time, drop harmlessly out of the ureter, and that others that are only 4 mm in diameter stubbornly remain in the ureter. Whether patients opt for watchful waiting or active intervention will, to a certain extent, depend on other factors, such as their job. Young, active patients may be very keen to opt for surgical treatment because they need to get back to work or their child-care duties, whereas some patients will be happy to sit things out. Discuss the options with patients so they are able to make a rational decision.

Indications for Intervention to Relieve Obstruction and/or Remove the Stone

1. Pain that fails to respond to analgesics, or that initially does so but then recurs and cannot be controlled with additional pain relief, is an indication for drainage of the kidney (by JJ stent insertion or percutaneous nephrostomy) or emergency de.nitive treatment of the stone.

2. Where there is an associated fever, one should have a low threshold for draining the kidney, and this is usually done by percutaneous nephrostomy.

3. Where renal function is impaired because of the stone (solitary kidney obstructed by a stone, bilateral ureteric stones, or preexisting renal impairment that gets worse as a consequence of a ureteric stone), the threshold for intervention is lower.

4. Obstruction unrelieved for >4 weeks can result in longterm loss of renal function. In a study of 239 patients presenting with unilateral ureteric stones, after 2 weeks the stones were still present in 143 patients (Holm-Nielsen et al. 1981). Of these 143 patients, 50% had renal obstruction de.ned by isotope renography; 11 of 31 patients (35%) with obstruction for >4 weeks developed varying degrees of irreversible renal damage. The problem with current imaging for stones, which nowadays is essentially CTU, is the absence of any information on the presence of renal obstruction (most urologists do not routinely obtain isotope renograms in patients with ureteric colic). However, what we do know from the Holm-Nielsen study is that only 50% of patients with ureteric stones that are still present at 2 weeks, have renographic evidence of obstruction. It seems reasonable to limit the period of watchful waiting for spontaneous stone passage to approximately 4 weeks and to intervene to remove the stone or drain the kidney (by, for example, JJ stent placement) if it has not passed at this time.

5. Personal or occupational reasons. As stated above, some patients will not be able to wait for spontaneous stone passage and therefore may accept the risks associated with active intervention. The classic example would be the airline pilot who is unable to .y until he is stone free.

Emergency Temporising and Definitive Treatment of the Stone

Where the pain of a ureteric stone fails to respond to analgesics or where renal function is impaired because of the stone, then temporary relief of the obstruction can be obtained by insertion of a JJ stent or percutaneous nephrostomy tube. This has the advantage of not taking much time to perform. However, the disadvantage is that the stone is still present. While the stone may pass down and out of the ureter with a stent in situ, in many instances the stone simply sits where it is and subsequent definitive treatment is still required. Furthermore, though a JJ stent can relieve the pain due to the stone, it can cause bothersome irritative bladder symptoms (pain in the bladder, frequency, and urgency). Having said this, a JJ stent will usually result in passive dilatation of the ureter so that subsequent stone treatment in the form of ureteroscopy is technically easier and therefore more likely to be successful. Similarly, by allowing passive dilatation of the ureter, fragments of stone produced by extracorporeal shock-wave lithotripsy (ESWL) may be more easily able to pass out of the ureter.

General options for de.nitive treatment of a ureteric stone are ESWL and ureteroscopic stone removal. ESWL is suitable for stones in the upper and lower ureter. Ureteroscopy can be used to treat stones at any level in the ureter, although access and fragmentation of stones in the lower ureter is generally easier

Whether you decide to carry out definitive stone treatment, and what type of treatment you offer, will depend on local facilities and expertise. Many hospitals do not have daily access to ESWL. In others, surgeons with experience of ureteroscopic stone fragmentation are not always available.

Emergency Treatment of an Obstructed, Infected Kidney

The rationale for performing percutaneous nephrostomy rather than JJ stent insertion for an infected, obstructed kidney is to reduce the likelihood of septicaemia occurring as a consequence of showering bacteria into the circulation. It is thought that this is more likely to occur with JJ stent insertion than with percutaneous nephrostomy insertion.

Other Non-Stone Causes of Acute Flank Pain

These include pelviureteric junction obstruction (PUJO), which is called ureteropelvic junction obstruction (UPJO) in North America, and infective causes such as acute pyelonephritis, emphysematous pyelonephritis, and xanthogranulomatous pyelonephritis.

Pelviureteric Junction Obstruction

This is a functional impairment of transport of urine from the renal pelvis into the ureter. It may be acquired or congenital. The majority of cases are probably congenital in origin, but do not always present in childhood. Indeed, many present in young adults. The precise cause of the aperistaltic segment of ureter that leads to congenital cases of this condition is not known. Acquired causes of PUJO include stones (the investigation and management of which is discussed above), urothelial tumours (transitional cell carcinoma), and inflammatory and postoperative strictures.

Not infrequently PUJO may present acutely with flank pain, which may be severe enough to mimic an ureteric stone. When imaging (nowadays usually a CT scan) demonstrates hydronephrosis, with a normal-calibre ureter below the pelviureteric junction (PUJ) and no stone (or tumour) is seen, the diagnosis of PUJO becomes likely, and a renogram (e.g., MAG3 scan) should be done to conform the diagnosis.