Use of Doppler ultrasonography and rigid ureteroscopy for managing symptomatic ureteric stones during pregnancy

Authors


Abdelnaser Kh Elgamasy, 4 Mohamed Affifi St, Mashroe Naser, Kafr Elzayat, Egypt, 31611. e-mail: elgamasy4@yahoo.com

Abstract

Study Type – Therapy (case series)
Level of Evidence 4

OBJECTIVE

To evaluate the use of Doppler ultrasonography (DUS) and rigid ureteroscopy (RU) for managing symptomatic ureteric stones during pregnancy.

PATIENTS AND METHODS

The study comprised 15 pregnant women with persistent renal pain; all were assessed with conventional US followed by DUS in both kidneys.

RESULTS

The mean period of gestation at presentation was 25.5 weeks. Stones were found in the right side in 11 patients (73%), in the left in three (20%) while no stone was found in the remaining patient (7%). There was a significantly higher mean resistive index in all 15 obstructed kidneys than in the contralateral normal kidneys. RU was used in all patients, with removal of the stones and fixation of JJ stent. All patients improved after the procedure and completed pregnancy safely up to full-term, except for premature labour in one patient.

CONCLUSION

DUS and RU are efficient for the diagnosis and treatment of symptomatic ureteric stones during pregnancy.

Abbreviations
RI

resistive index

(D)US

(Doppler) ultrasonography

RU

rigid ureteroscopy.

INTRODUCTION

Significant anatomical and functional changes occur in pregnancy; of these, hydronephrosis has particular relevance in the diagnosis and presentation of urolithiasis [1]. The reported incidence of urolithiasis is ≈1 in 1500 pregnancies. Overall, it is unlikely that pregnancy increases the incidence of stone disease, despite several physiological changes that theoretically could increase the risk of stone formation [2,3]. The metabolic conditions affecting the risk of urolithiasis in pregnancy are hypercalciuria, hyperuricosuria and hypercitraturia. In addition, mechanical (enlarged gravid uterus) and hormonal factors are risk factors for stone formation during pregnancy [4,5].

Conventional ultrasonography (US) is limited in the diagnosis of early obstruction because acutely obstructed kidneys might show only mild pyelocaliectasis or none at all. The diagnosis of urolithiasis by US during pregnancy is further complicated by dilatation of the upper urinary tract, which occurs in normal pregnant women who do not have obstructive disorders such as calculi or tumours [6,7].

The use of Doppler US (DUS) has had a great impact on the diagnosis of ureteric obstruction in pregnant patients. It was found that the resistive index (RI) of the kidneys of pregnant patients were not significantly different from those in non-pregnant patients. In addition, the RI was <0.70 in all pregnant patients, whether or not there was dilatation from pregnancy [8]. These findings suggest that an elevated RI during pregnancy (>0.70) should not be attributed to the normal physiological changes of pregnancy [9,10].

In the present study, we evaluated the use of DUS as a diagnostic tool and rigid ureteroscopy (RU) as an operative tool for managing obstructive ureteric stones during pregnancy.

PATIENTS AND METHODS

Between June 2003 and June 2008, 42 consecutive cases of obstructive ureteric stones during pregnancy were managed at the urology department of Tanta University in Egypt and Al-adawani general hospital, Taif, Saudi Arabia. At presentation, patient age, parity and duration of pregnancy were recorded. Previous urological histories were reported and routine laboratory investigations done. Every patient was then examined with conventional grey-scale US followed by DUS with calculation of the intrarenal RI in both kidneys.

With a full bladder, a standard obstetric ultrasonogram was first taken to determine gestational age and to exclude obstetric complications as a cause of symptoms. Both kidneys were then examined with real-time US, using a multifrequency (3.5–5-MHz) sector transducer (Model Nemio XG SSA-580, Toshiba, Japan). Renal size, echogenicity and the presence of perinephric fluid or renal calculi were noted. The presence and degree of dilatation of the collecting systems were determined and were subjectively graded as absent, mild, moderate or marked. The dilated ureter, if present, was followed as distally as possible and its relationship to the iliac vessels analysed, aided by colour imaging. The presence and position of an intra-ureteric calculus were documented.

DUS, using the highest frequency that gives measurable wave-forms, was used to record waveform tracings from the intrarenal arteries. Arcuate arteries (at the corticomedullary junction) or interlobar arteries (adjacent to medullary pyramids) of the upper, middle and lower poles of each kidney were examined using a 2–4-mm Doppler gate. Colour imaging was used when necessary to help identify these vessels. Wave-forms were optimized for measurements using the lowest pulse-repetition frequency without aliasing (to maximize wave-form size), the highest gain without obscuring background noise, and the lowest wall filter. Three to five reproducible wave-forms from each kidney were obtained, and RIs from these wave-forms were averaged to calculate mean RI for each kidney. In each patient the mean RI for the contralateral normal kidney was obtained and compared with the symptomatic side. Any RI of >0.70 was considered suggestive of pathological obstruction.

After hospitalization, conservative treatment was given for every patient; this included analgesics, antispasmodics and fluids. Antibiotics (first- and second-generation cephalosporines or ampicillin-salbactum) were given in cases of infection. Patients with a good response on conservative treatment were discharged and followed up in the outpatient clinic. Only patients with persistent colic or persistent fever were enrolled in the present study, and had RU with a ureteric JJ stent placed under direct visualization or with US guidance. The technique of RU was the same as in other populations (nonpregnant women, and men). The same steps were used (visualizing cysto-urethroscopy, guidewire insertion, balloon dilatation, then insertion of teh ureteroscope). In this study, a 9.5 F ureteroscope was used. The insertion of the JJ stent without fluoroscopy required special care, as there was some difficulty in some cases due to possible kinking of the guidewire. Gentle withdrawal of the guidewire with gentle insertion of the stent facilitated the procedure in all cases. The policy was insertion of a good quality JJ stent and retaining it inside the patient until after delivery, provided that there were no complications, e.g. persistent infection, colic or severe LUTS.

Patients were followed closely until delivery. At 1 month postpartum, patients had repeat US and the JJ stent was removed endoscopically. Further treatment was added according to the condition of each patient. Data were analysed using Student’s t-test, with P < 0.05 considered to indicate significance.

RESULTS

Over a period of 5 years, 42 pregnant women presented with ureteric stones and renal colic; 27 improved with conservative treatment (stones either passed spontaneously during pregnancy or after delivery) and only 15 needed urgent RU after failure of conservative treatment, and were enrolled in the present study. The age and period of gestation at presentation are shown in Table 1. There was a history of ESWL, with neglected follow-up and pyelolithotomy, in two patients (13%) and one (7%), respectively. Infection was present in 10 patients (67%) with a positive culture in six (40%). In all patients, the main presenting symptoms were persistent renal pain, fever, nausea and vomiting, while calculus anuria was present in only one (7%); haematuria, either gross or microscopic, was present in nine (60%). The site and laterality of the stones are also shown in Table 1.

Table 1. 
The data of the 15 pregnant women
VariableMean (sd, range) or n (%)
History of pyelolithotomy 1 (7)
History of ESWL + neglected follow-up 2 (13)
Age, years25.9 (5.7, 18–38)
Infection10 (67)
Haematuria 9 (60)
Gestation, weeks25.9 (2.25, 24–30)
Laterality
 Right 11 (73)
 Left 3 (20)
 No stone 1 (7)
Site of the stone
 Upper third 2 (13)
 Middle third 2 (13)
 Lower third10 (67)
High RI15 (100)

Conventional US (Fig. 1a) was useful in the diagnosis of obstruction and hydronephrosis in 14 patients (93%), and one of them with perirenal fluid collection; the remaining patient (7%) had no collecting system dilatation. Hydronephrosis was mild in five patients, moderate in six and severe in two. US detected ureteric stones (Fig. 1b) in 12 patients (80%) and missed stones in two of 14 with documented ureteric stones. The missed stones were located in the lower third of the ureter, deep in the pelvis.

Figure 1.

Urolithiasis in a 25-year-old pregnant woman with right flank and right lower quadrant pain in the third trimester. a , Sagittal US image of the right kidney shows moderate hydronephrosis. b , US image of the bladder shows a distal right ureteric calculus (arrow). c , DUS image shows an elevated RI of 0.76 in the right kidney.

The mean (sd) RI was elevated in all 15 obstructed kidneys (Fig. 1c), at 0.78 (0.07), which was significantly higher than the mean RI for the contralateral normal kidneys of 0.60 (0.04) (P < 0.001). In one patient with a perirenal fluid collection, the elevation in RI was mild (0.74), but still significantly higher than the contralateral normal kidney (0.61). One obstructed kidney (7%) had no pyelocaliectasis on conventional US and showed an elevated RI on DUS at the same time. The increase in RI occurred before collecting system dilatation in this last patient.

Under general anaesthesia in 10 (67%) and spinal anaesthesia in five patients (33%), all patients had RU without the use of C-arm fluoroscopy. A guidewire was inserted, followed by balloon dilation, in five patients (33%) while direct RU without dilation was used for 10 (67%). In 12 patients (80%) the stones were either removed by a Dormia basket or fragmented by pneumatic lithotripter, while stone king forceps were used to remove multiple stones fragments (steinstrasse) in two (13%). In the remaining patient no stones were found but there was a definite obstruction at the pelvic brim, as shown by difficulty in guidewire insertion at this level, and this was managed by direct RU. In the last patient, only a JJ stent was inserted. The proper position of the JJ stent in the renal pelvis was verified by US during surgery. All patients improved after the procedure and completed their pregnancy safely up to full-term. Only one premature labour (7%) was recorded at 36 weeks of pregnancy; this was managed by an obstetrician. After 24 h of conservative treatment, the condition was terminated by normal vaginal delivery. Migration of the JJ stent outside the external urethral orifice was recorded in another patient (7%) and was removed with no complications.

DISCUSSION

Urinary stones during pregnancy are uncommon; the typical diagnostic course and surgical management used in nonpregnant females must be re-evaluated in pregnant women [11,12]. In the present study, renal pain was the main symptom at presentation, but haematuria and infection were also present in 60% and 67% of patients, respectively. In the general population the usual classic presentation of renal colic due to an obstructing calculus is unmistakable. However, this condition can present differently in the expectant mother. The anatomical changes of the gravid uterus, abdomen and pelvis can alter the perception, radiation, and localization of pain, making the clinical assessment of abdominal pain difficult. Also, pregnant women can have abdominal and flank pain, nausea, vomiting and irritative LUTS unrelated to urolithiasis. It is thus important that the practitioner considers stone disease in pregnant women who have abdominal or flank discomfort or LUTS [9].

In the present study the mean gestational age was 25.5 (2.25) weeks, and right-sided stones were found in about three-quarters of the patients. Generally, patients with symptomatic stones present in the second or third trimester [11,12]. At this point, the gravid uterus has enlarged above the pelvic brim and can impinge on the distal ureter (more on the right side). In one patient in the present study, with persistent right renal pain, no stones were found after RU, but a definite ureteric obstruction was found, with complete resolution of symptoms after the procedure.

The diagnosis of urolithiasis has traditionally focused on plain radiography and excretory urograms. However, because of concerns about radiation exposure to the fetus, US has been advocated as the imaging method of choice in pregnant women with suspected urinary stones. In our study, US was the only imaging method used in the diagnosis and management of patients with obstructing ureteric stones. Conventional grey-scale US was successful in detecting the obstructing ureteric calculus in 80% of patients. The missed stones were located deep in the pelvis in the lower third of the ureter. There was little difficulty in detecting stones at the proximal ureter, near the PUJ, or at its intravesical distal end. Our results are in agreement with those of Erwin et al.[13], who identified the stone in 15 of 18 patients, including 11 stones at the vesico-ureteric junction.

It is generally accepted that conventional US is limited in the diagnosis of early obstruction. However, ureteric dilatation occurs only above the pelvic brim in physiological hydronephrosis, but if this dilation extends below the pelvic brim, one should consider distal ureteric obstruction [11–14]. Fourteen of 15 obstructed kidneys (93%) in the present study had pyelocaliectasis; the remaining one obstructed kidney (7%) had no collecting-system dilatation on real-time US but an elevated RI that indicated obstruction. Our finding that only 7% of obstructed kidneys had no pyelocaliectasis seems to differ from the study by Laing et al.[14], who found that 35% of acutely obstructed kidneys had no pyelocaliectasis. However, this difference might be explained by the few patients included in the present study, the period between the onset of renal obstruction and US, and the fact that the study of Laing et al. included only non-pregnant patients.

The use of DUS has been reported to increase the accuracy of evaluating acute calculus obstruction in nonpregnant patients. Animal research indicates that acute obstruction increases the renal arterial resistance within a few hours. This intrarenal vasoconstriction was reported to be a local effect and was not seen in normal contralateral kidneys in patients with unilateral obstruction [15]. In our study, we found a higher mean RI in all 15 acutely obstructed kidneys than the normal mean RI in the contralateral normal kidneys. The elevated RI confirmed the obstruction before the development of collecting-system dilatation in one kidney. Our findings are in agreement with the study by Shokeir et al.[16] who examined 22 pregnant women with acute unilateral ureteric obstruction due to stone disease, and concluded that measurements of the difference between the RI of the corresponding and contralateral kidney is a sensitive and specific test that can replace IVU in the diagnosis of acute unilateral ureteric obstruction in pregnant women. This finding was further supplemented in a more recent study by Onur et al.[17], who found that the mean RI of 16 obstructed kidneys was significantly greater than that of 16 unobstructed contralateral kidneys, and concluded that in acutely obstructed kidneys, renal DUS can detect altered renal perfusion before pelvicalyceal system dilatation, and distinguish obstructed and unobstructed kidneys evaluated for suspected renal colic. In our study, in one obstructed kidney with a small perirenal fluid collection caused by pyelosinus extravasation, the increase in RI was mild. This mild increase despite acute obstruction reflects the partial decompression of the collecting system, so that true obstruction is no longer present. Our finding is in agreement with a previous study [18] where pyelosinus extravasation was responsible for two of three normal DUS findings in obstructed kidneys. In that study, the authors advised that in the presence of even a small perirenal or peri-ureteric fluid collection, one should immediately question the finding of a normal RI in a possibly obstructed kidney. They added that a normal RI might accurately reflect decompression of the collecting system but does not imply that the original cause of obstruction has been removed.

Currently, US is considered a suitable first-line imaging study for the diagnosis of obstructing urolithiasis in pregnancy. When US fails to establish the diagnosis, MR urography should be recommended as a second-line test. A high sensitivity has been reported for detecting urinary tract dilatation and identifying the site of obstruction. However, the limitations of MR urography include limited visualization of small calculi and relatively high cost [19,20].

In the present study, 27 patients (77%) passed the stones spontaneously, either during pregnancy or after delivery. This finding is in agreement with that of Parulkar et al.[21], who reported that 64% of their 70 patients passed their stones with no surgical intervention. Another two studies reported 70–84% spontaneous passage of stones with conservative treatment [12,22].

With continued advances in endoscopic technology and endourological techniques, RU has become less invasive and less traumatic. Although traditionally placed under fluoroscopic guidance, ureteric stents can be placed under direct visualization via RU or with US guidance [23]. In the present study, a 9.5 F ureteroscope was used with complete success. The procedure was carried out either without or with easy ureteric dilation. Several small series have reported stone-free rates of 70–100%, with displacement of proximal ureteric stones into the kidney accounting for most residual calculi [24–26]. Studies have shown that the holmium laser is currently the preferred means of lithotripsy for large stones [27,28]. However, in vitro studies suggest that the peak pressures generated by endoscopic lithotripsy are unlikely to damage fetal hearing, although the data are limited and largely theoretical [29].

In a recent meta-analysis the safety of ureteroscopic stone removal in pregnant patients was found to be not significantly different from that in nonpregnant females [30]. In conclusion, a conservative approach is recommended for the initial management in all pregnant patients with ureteric calculi and renal colic. However, if the symptoms persist or complications develop, DUS and RU can be used successfully for diagnosis and treatment.

CONFLICT OF INTEREST

None declared.

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