Correspondence *Urology Sydney, Level 1 St George Private Hospital, 1 South Street, Kogarah, Sydney, NSW 2217, Australia

Email sphipps27@aol.com

The case

A 33-year-old woman presented to the renal outpatient clinic with a headache. She had given birth 3 months previously at 42 weeks' gestation by emergency caesarean section, after a labor complicated by uterine rupture. Her pregnancy had not been complicated by any form of hypertension. She was multiparous and had delivered twice previously by emergency caesarean section. She gave no other history of abdominal surgery or of abdominal pain. Examination was unremarkable, but she was found to be markedly hypertensive at 180/120 mmHg. She was afebrile and full blood count, urinalysis and serum creatinine level were normal.

Renal ultrasonography demonstrated severe left hydronephrosis and hydroureter to the level of the distal ureter. The cortical thickness of the left kidney was preserved.

She was admitted to hospital for immediate medical management of her hypertension and for placement of a left percutaneous nephrostomy under local anesthetic. A nephrostogram showed a dilated ureter down to an area of complete obstruction distally (Figure 1). The kidney produced normal volumes of urine via the nephrostomy.

Figure 1 Nephrostogram of the distal left ureter showing the region of obstruction (posteroanterior film).

 

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The patient's blood pressure returned to normal after treatment with nifedipine and prazosin. All antihypertensives were discontinued 1 week after nephrostomy placement and she remained normotensive thereafter, highlighting the effect on her blood pressure of relieving the obstruction.

Subsequent retrograde ureterography and rigid ureteroscopy demonstrated that the level of obstruction was 3 cm proximal to the vesicoureteric junction (Figure 2). The appearances were consistent with iatrogenic injury to the distal ureter. It was not possible to place a guidewire retrogradely past the level of obstruction.

Figure 2 Distal left ureter observed on retrograde contrast fluoroscopy.

No contrast agent passes proximal to the region of obstruction.

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The patient was readmitted for combined antegrade and retrograde management of the ureteric stricture. Simultaneous antegrade and retrograde urography confirmed that the stricture was short. A guidewire would not pass the stricture antegradely. Under fluoroscopic imaging, a cobra catheter (Cook Urological Inc., Bloomington, IN) was manipulated to the proximal side of the stricture. A 7 Fr rigid ureteroscope was simultaneously passed to visualize the distal side of the stricture. When the cobra catheter could be seen tenting the stricture from above, a stiff guidewire was passed through the stricture against the tip of the catheter. A soft-tipped guidewire then passed easily to the kidney. With the guidewire in place and with a 300 m fiber, a holmium yttrium-aluminum-garnet (Ho:YAG) laser at 1.0 J power and 15 Hz was used to incise the stricture anteromedially, such that the ureteroscope passed easily (Figure 3). A 7–14 Fr endopyelotomy stent was then placed, with the larger segment across the stricture site (Figure 4). The nephrostomy was removed the following day.

Figure 3 Fluoroscopic image showing the passage of the ureteroscope proximal to the stricture.

 

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Figure 4 Fluoroscopic image showing the endopyelotomy stent in position.

 

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The patient returned for removal of the endopyelotomy stent and placement of a standard 'double J' ureteric stent 1 month later. A retrograde study showed a normal ureter. The stent was removed 2 months later. Rigid ureteroscopy at this time showed a patent ureter (Figure 5), and a further retrograde study was normal. The patient remains normotensive.

Figure 5 Ureteroscopic images of the site of the treated stricture following stent removal.

 

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Discussion of diagnosis

We report the case of a 33-year-old woman with iatrogenic ureteric injury presenting with severe hypertension causing headache. Iatrogenic ureteric injury remains relatively uncommon, and is said to affect between 0.5% and 1% of all abdominal and pelvic surgery;¹ 50% of such injuries occur during the course of gynecologic surgery. The risk of maternal morbidity, including ureteric injury, increases with multiple repeat caesarean delivery.² The majority of iatrogenic ureteric injuries are recognized and repaired during the course of surgery. Of those that are not, most present early in the postoperative period with loin pain, fever or both. The mode of presentation observed in this patient is unusual. Although iatrogenic ureteric injury has been documented as presenting with hypertension,³ such a case presenting with headache has not. Also, hypertension is not usually severe enough to cause headache or to necessitate hospital admission and immediate treatment.⁴

The association between hypertension and ureteric obstruction has been studied in detail; however, the mechanisms of hypertension as a result of bilateral ureteric obstruction (BUO) or unilateral ureteric obstruction (UUO) are thought to be very different. Hypertension is said to be associated with about 80% of BUO cases, with only 20% of cases of acute UUO and with a significantly lower number of cases of chronic UUO.⁵

The mechanism of hypertension in BUO is volume-mediated, with the majority of patients with BUO presenting in a state of fluid overload. The mechanism of hypertension in UUO is less clear, but seems to result from the release of a number of vasoconstrictor substances from the obstructed kidney, leading to an increase in vascular resistance across the affected renal unit. In the later stages of obstruction, vasoconstriction occurs in both pre-glomerular and post-glomerular arterioles. The renin–angiotensin system is thought to be activated, with elevated levels of plasma renin demonstrated in cases of UUO.⁶ Renin secretion seems to be enhanced in the affected kidney,⁷ and there might be a compensatory fall in renin production in the contralateral kidney. Also, increased secretion of angiotensin II by the affected kidney has been shown in UUO.⁸ Eicosanoids (prostaglandins and thromboxane) might also have a role in the development of hypertension in UUO. Eicosanoids exist as both vasodilators and vasoconstrictors, and both forms have been studied in detail and implicated in the development of hypertension in this setting.⁹

Following relief of the obstruction in this case, it is interesting that no diuresis was observed in the hydronephrotic kidney. Indeed, normal volumes of urine were produced after nephrostomy placement. The explanation for this is presumably that the patient was not fluid or solute overloaded, and the affected kidney was functioning normally with preserved urinary concentrating ability. Isotope renography was not performed because the cortical thickness of the kidney was normal on ultrasonography at presentation. Normal function of the kidney following prolonged and complete ureteric obstruction is well recognized,¹⁰ but why in some cases function is preserved, whereas in others renal function deteriorates, is not clear. Presumably this preservation of function depends upon intrinsic 'renal reserve' capacity, which is difficult to measure. It is possible that in this case the obstruction developed gradually, though within 3 months of delivery. The mechanism of iatrogenic ureteric injury can be complete or partial transaction, crush, ligation or ischemia. A stricture secondary to ischemic ureter injury might develop slowly, which might explain the lack of loin pain and delayed presentation in this case.

Treatment and management

Distal ureteric strictures have traditionally been managed with open surgery, most commonly with ureteroneocystotomy with or without psoas hitch or Boari flap, unless stricture length allows excision and ureteroureterostomy. The use of endourological approaches to treating distal ureteric strictures has become increasingly common over the last 10 years. A number of different modalities have been used to incise ureteric strictures. Whereas a cold knife or balloon dilatation cannot offer hemostasis, and electrocautery techniques might involve the risk of damage to surrounding tissue, the Ho:YAG laser has been found to be an excellent instrument for endoureterotomy, as the penetration depth of the energy is small, precise cutting is possible, and scarring is minimal.

There is a number of reported series of Ho:YAG incision of various types of ureteric stricture.¹¹ A few reports describe the use of the combined antegrade and retrograde approach to completely obliterating ureteric strictures of differing etiologies and at different sites. Of these, however, only one small series describes the use of the Ho:YAG laser.¹² Stricture length is an important determinant of outcome. Whatever the site of the stricture or the treatment modality used, the majority of authors report better results when treating shorter lesions (up to 2 cm).¹³

Conclusions

Iatrogenic ureteric injury presenting with headache has not been previously reported. This interesting case illustrates that UUO can present with severe hypertension that is curable with relief of the obstruction. It also demonstrates that short, completely obliterating, distal ureteric strictures can be effectively managed by entirely endourological means.

References

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Subject areas under which this article appears: Female urology