Introduction

The development of symptomatic urolithiasis in pregnancy is no higher than in the general population, affecting 1 in 200–1,500 pregnant women, however its occurrence brings a unique set of challenges to the urologist.^1,2 These challenges include the importance of minimizing radiation exposure to the developing fetus, decreasing exposure to anesthesia, symptom management, and mitigating the risk of preterm labor. Each management option must be weighed carefully in terms of risks and benefits. Symptomatic urolithiasis has been associated with pregnancy complications including pre-eclampsia, low birth weight, need for C-section, and a twofold increase in risk of preterm delivery.^1–3 Due to the complexity of managing these patients, a multidisciplinary approach is critical, involving the urologist, obstetrician, radiologist, and a neonatologist. Recently, there have been 2 care pathways, one providing multidisciplinary guidelines for the treatment of pregnant stone patients and the other proposing a treatment algorithm, published with the goal to streamline the urological care of pregnant patients with urolithiasis.^4,5 Specifically, American Urological Association and multi-disciplinary guidelines recommend conservative management with a trial of passage for patients who are tolerating symptoms with oral analgesia (see Figure).^4–6 Stone passage rates have been published to be around 50%–80%.^7,8 In addition, 50% of patients who do not pass their stones during pregnancy go on to pass them during the post-partum period.⁷ Patients who are deemed appropriate for conservative management can be prescribed acetaminophen, tamsulosin, and as needed narcotics for symptom management. Tamsulosin is a Category B medication, meaning that its use is reasonable in pregnancy if deemed clinically necessary.⁵

Figure. Management algorithm of symptomatic urolithiasis.

If conservative management fails, then proceeding with definitive treatment with ureteroscopy during pregnancy is now a well-established practice. Advances over the past few decades in laser technology, flexible grasping devices, and smaller semi-rigid and flexible ureteroscopes have facilitated treatment in challenging clinical scenarios such as pregnancy.⁹

Definitive Stone Treatment during Pregnancy

Ureteroscopy with laser lithotripsy should be offered in noncomplex scenarios, when conservative management fails, or in those patients where complexity has been appropriately managed (see Figure).^4–6 Ureteroscopy has been shown to be safe in pregnancy with similar complication rates to the nonobstetric population with the caveat that one must use minimal radiation and keep operative time as short as possible.⁹ Techniques to decrease the use of radiation include using low dose and pulsed settings, pelvic shielding, tactile placement of wires, and use of ultrasound to confirm wire placement within the kidney. The timing of proceeding with ureteroscopy during pregnancy is critical, with the best time being in the second trimester or early third trimester. However, in the third trimester there is an increased risk of preterm labor. Definitive management with ureteroscopy is not typically recommended during the first trimester as anesthesia can interfere with fetus development, and there is higher risk of pregnancy loss during the first trimester in general.^4,5,10 If the decision to proceed with ureteroscopy is made, the patient’s obstetrician should be actively involved to help direct appropriate monitoring of the mother and fetus.

The benefits of proceeding with ureteroscopy during pregnancy are threefold. First, it offers definitive stone treatment with earlier relief of symptoms and saves patients the potential need for a procedure during the challenging post-partum period. Second, compared with serial stent exchange, definitive treatment can decrease the temporal exposure of the developing fetus to anesthesia and radiation exposure.^4,5 Third, it is more cost-effective than serial stent exchanges.¹¹ Data on percutaneous nephrolithotomy during pregnancy are limited, but it is generally considered contraindicated. However, a recent meta-analysis including 16 patients demonstrated that it can be safe and it is feasible; thus, it may be considered as an absolute last resort in very experienced hands when there are no alternatives.¹² Shock wave lithotripsy remains contraindicated in pregnancy.^4,5

Temporary Drainage Is Still Necessary at Times

Despite conservative management being preferred, and definitive management with ureteroscopy being well-accepted when conservative management fails or isn’t appropriate, there are still indications for temporary drainage at times. If there is concern for infection, complex anatomy (ie solitary kidney), comorbidities (ie renal dysfunction), bilateral obstruction, large stone burden, or pregnancy complications, then temporary drainage of the collecting system is required.^4–6 If intervention is indicated but there are inadequate resources or the urologist is inexperienced, then temporary drainage may be necessary as well. The decision to proceed with ureteral stent or percutaneous nephrostomy (PCN) tube is a passionately debated topic between urologists and interventional radiologists. Lee et al recommend first-line placement of ureteral stents over PCN tube placement.⁴ Their reasoning is that prone positioning for PCN placement is difficult due to the gravid uterus and, more concerningly, pregnant patients have an increased risk of aspiration when placed in this position. Ultimately, the method of collecting system drainage should be based on shared decision making with PCNs being necessary in specific situations such as if there has been prior genitourinary reconstruction or if retrograde stenting failed.

After temporary drainage has been performed, if definitive management is not an option then frequent exchange, every 4–6 weeks, of indwelling tubes is required. This is due to increased encrustation of indwelling tubes because of physiological changes of pregnancy. These changes include increased excretion of sodium, calcium, and uric acid in the urine.¹³

Conclusion

The management for pregnant patients with symptomatic urolithiasis causes angst for the urologist, but by following care pathways and guidelines this need not be the case. Avoidance of temporary drainage with first conservative management, and second, definitive management, when clinically appropriate, should be offered as the first-line recommendations for these patients. The use of temporary drainage will always remain a part of the management of our pregnant patients, though it can be reserved exclusively for scenarios when it is necessary.