Ureteroscopy in Pregnancy:

Management of urinary calculi in pregnancy: a review

Nephrolithiasis during pregnancy can represent a clinical dilemma because of potential risks to both mother and fetus. While the incidence of symptomatic nephrolithiasis during pregnancy varies between 1 in 244 to 1 in 2000 pregnancies, the actual incidence is likely to be higher. A significant proportion of patients with asymptomatic renal calculi are detected incidentally in the nonpregnant population compared with pregnant women. Factors that contribute to the diagnostic challenges include anatomic and physiologic changes to the female urinary tract during pregnancy and the limitations on the use of ionizing radiation. The treatment of such patients requires a multidisciplinary team approach involving the urologist, obstetrician, and radiologist. The potential hazards of intervention (either surgical or medical) and anesthesia need to be considered carefully.

Ureteroscopy as a first-line intervention for ureteral calculi in pregnancy

BACKGROUND AND PURPOSE

Renal colic in pregnancy presents a diagnostic and therapeutic challenge. When conservative therapy fails or is not indicated, temporary measures such as ureteral stenting are often chosen as a first-line intervention, postponing definitive management until after delivery. We propose that advances in endoscopic equipment and anesthesia techniques dictate a more definitive strategy.

PATIENTS AND METHODS

A retrospective analysis was performed on 10 consecutive pregnant patients presenting with renal colic necessitating intervention between April 1998 and April 2000. The mean patient age was 23 (range 17-31) years. One patient presented during the first trimester, six in the second, and three in the third. Four of the patients had a history of stone disease. All patients had flank pain at presentation, six on the left side and four on the right. Hematuria, fever, and nausea were present in eight, one and two patients, respectively.

RESULTS

Ultrasound scanning was performed in all patients and showed a low sensitivity (28.5%) when compared with intraoperative findings. Ureteroscopy (rigid and/or flexible) was performed as a first-line intervention in six patients, in two of whom no stone was found. Percutaneous nephrolithotomy was carried out in one patient presenting with a nephrostomy tube. Double-J stents were placed in only three patients with specific indications, namely urinary infection, late gestational phase, and difficult ureteroscopy secondary to a narrow ureter. No obstetric or urologic complications were noted. The mean size of the stones retrieved in seven patients was 7 mm.

CONCLUSIONS

Ureteroscopy may be considered a safe and effective first-line definitive therapeutic option in pregnant patients requiring intervention for stone disease.

Measurement of sound emission by endoscopic lithotripters: an in vitro study and theoretical estimation of risk of hearing loss in a fetus

BACKGROUND

There is concern about applying intraureteral lithotripsy in pregnant patients, as the sound created by the equipment may damage fetal hearing.

MATERIALS AND METHODS

The sound intensities produced by electrokinetic, pneumomechanic, holmium laser, ultrasound, and electrohydraulic intraluminal lithotripters were measured in an in vitro model.

RESULTS

The purely mechanical modalities (electrokinetic and pneumomechanic) generated lower peak pressures than the other devices. Theoretical calculations were performed based on the fact that in vivo, the sound path and the fetal middle ear cavities are filled with fluid. Calculated pressure levels that give displacement amplitudes of the tympanic membrane, the ossicles, and the basilar membrane comparable to hearing loss risk criteria for airborne impulsive noise are greater than measured for all of the lithotripters. The fluid-filled middle ear thus seems to give the fetus protection against sound. The fluid also improves the symmetry of the cochlea structure, reducing the influence of direct bone transmission.

CONCLUSIONS

The peak pressure of the sound emitted by lithotripsy in the ureter during pregnancy is unlikely to be harmful to fetal hearing. Other risk factors, such as the form of the sound waves and the pulse duration were not evaluated. The theoretical assessments are simplified, and one should be careful about drawing conclusions from theoretical considerations and calculations alone.