ANSWER 72
The pain’s acute onset, colicky nature and radiation are typical of ureteric colic, the like-
liest cause of which is a stone. Renal stones can cause infection, or chronic infection can
cause scarring which provides a nidus for stone formation.
The high fever and leucocytosis indicate that she has another episode of acute pyelonephritis.
The patient is in renal failure; at this stage it is not clear whether this is all acute, with previ-
ous normal renal function, or whether there is underlying chronic renal failure with an acute
exacerbation. Both kidneys are affected, as renal function remains normal if one kidney is
healthy. Until proved otherwise it must be assumed that any element of acute renal failure is
due to obstruction by a stone; her illness is too short for significant prerenal failure due to
fluid loss or septicaemia. Acute pyelonephritis per secan cause acute renal failure but this is
very uncommon.
She has hypertension. Her blood pressure is raised, but pain and anxiety could easily account
for that. However, there is grade I retinopathy.
The overall interpretation at this point is that she is a medical emergency with acute
pyelonephritis in an obstructed urinary tract.
The most important investigation now is an ultrasound of the urinary tract. This shows
stones in both kidneys; the left kidney is reduced in size to 10 cm, with a scar at its upper
pole, and is not obstructed; the right kidney is larger at 11 cm but is obstructed as shown
by a dilated renal pelvis and ureter; its true size would be less than 11 cm.
The immediate management is an intravenous antibiotic to treat Gram-negative bacteria,
E. colibeing the commonest cause of urinary tract infections, after urine and blood samples
are taken for culture. Intravenous fluids should be given (she has vomited) according to fluid
balance, carefully observing urine output.
The obstruction must be relieved without delay; the method of choice is percutaneous
nephrostomy and drainage. In this procedure a catheter is inserted under imaging guidance
through the right loin into the obstructed renal pelvis. Not only will this relieve the obstruc-
tion but it allows the later injection of X-ray contrast to define the exact site of obstruction
(percutaneous nephrostogram). This was done 48 h later and showed hold-up of the contrast
at the vesico-ureteric junction, a typical place for a stone to lodge. The patient passed the
stone shortly afterwards, as often happens if it is small enough; otherwise it would have to
be removed surgically. Her fever, pain and leucocytosis rapidly resolved. Her renal function
improved but stabilized at a creatinine of 180&mol/L, i.e. she has chronic renal failure.
Blood biochemistry revealed no underlying abnormality to cause the stones: calcium,
phosphate, alkaline phosphatase and uric acid were normal. The probable cause of her
renal disease is reflux nephropathy because of her sex, history of recurrent infections and
the scar on the left kidney. There is a familial tendency for this disease, and her mother
may have had it. The patient’s children should be screened for it in infancy.
Long-term management comprises prophylactic antibiotics, immediate treatment of acute
urinary infections, control of hypertension and regular measurement of renal function.
These should be supervised from a fixed base, despite the patient’s peripatetic existence.
- An obstructed and infected urinary system is an emergency requiring immediate treatment.
- Prophylactic treatment of recurrent urinary tract infections should be considered in
every case, although not necessarily indicated in every one.