Don’t Get Stuck! A Review of ED Management of Symptomatic Urolithiasis in Pregnancy
24 yo G2P0001 woman at 13 weeks’ gestation with no significant past medical history presents to the Emergency Department with acute onset left flank and abdominal pain, nausea, and vomiting that began 12 hours prior to presentation.
She reports her pain at 7-10/10 in severity and that it has been constant and feels like “punching” in her abdomen.
She denies any fever, chills, dysuria, hematuria, constipation, diarrhea, vaginal bleeding, or cramps.
Vitals: T 36.9ºC, BP 91/54, HR 129, RR 18, SpO2 97%
Exam: abdomen soft, normal bowel sounds, diffuse tenderness to palpation worse on the left side of her abdomen and in the suprapubic region. + Left CVA tenderness. No rebound tenderness or guarding.
Labs remarkable for: WBC 3.53, Cr 0.7, b-HCG 76,071, and UA with +nitrites, +leukocyte esterase, small hemoglobin pigment, 5 WBC/hpf, 2 RBC/hpf, many bacteria.
Transabdominal pelvic US: remarkable for intrauterine pregnancy at 13w5d gestation, and a 5 mm stone in left distal ureter near ureterovesical junction with mild left hydronephrosis.
Patient was diagnosed with symptomatic urolithiasis. Her urinalysis was also concerning for a UTI, and urine culture was sent. The case raised several interesting questions, including…
Clinical Question: How should symptomatic urolithiasis in a pregnant patient at < 20 weeks’ gestation be managed in the ED?
Summary of Evidence:
Evidence for conservative treatment and awaiting spontaneous stone passage
Among all adults, first line treatment is pain management, hydration, and waiting for stone passage. American Urological Association (AUA) guidelines recommend observing stones <10 mm if symptoms can be controlled, as the panel’s meta-analysis showed 68% of stones <5mm and 47% of stones >5 and <10mm pass spontaneously in nonpregnant adults.(1)
Conservative management is preferred in pregnancy,(2) but analyses of stone passage rates in pregnancy are retrospective and vulnerable to biases, which may explain variable estimates.
One study of 244 pregnant and 5,712 nonpregnant women with urinary calculi of similar sizes found spontaneous stone passage was significantly more common in pregnancy (80.8% vs. 47.1%).(3) While a control group is valuable, it was not clear if there were differences between groups (e.g. in stone location) that may have affected passage rates.
By contrast, a study of 112 pregnant women with urolithiasis showed only 48% passed stones spontaneously. However, there were no data on stone size, and the study excluded patients who did not present for follow-up.(4) If those who passed stones were less likely to follow-up, the study may have underestimated spontaneous stone passage rates.
Pain management for symptomatic urolithiasis in pregnancy
NSAIDs are often used for pain management in symptomatic urolithiasis, but are FDA category C in pregnancy (adverse effects in animal studies) so avoided when possible. (5-7)
Instead of NSAIDs, acetaminophen (FDA category B; no well controlled studies in pregnant women) is considered safe in pregnancy. (5, 8)
Opioids, such as morphine(9), are typically considered safe for acute pain and may be needed when pain is severe. (2, 10) Codeine in early pregnancy is associated with congenital malformations and should not be used. (5, 9)
Medical expulsive therapy
A meta-analysis of 1,384 nonpregnant adults in 8 randomized placebo-controlled trials of the alpha blocker tamsulosin showed tamsulosin was associated with significantly higher rates of passage for larger stones (5-10mm), but no significant effect for stones <5mm. (11)
Tamsulosin is FDA category B,(12) and no randomized trials address efficacy in pregnancy. One retrospective matched study of 27 pregnant tamsulosin-treated patients and 54 pregnant controls found 24% higher rate of stone passage with tamsulosin (difference not statistically significant), and no significant differences in any adverse outcomes, such as pyelonephritis. (12) One study limitation was that no information on stone size or location was provided.
Similar retrospective study of pregnant women compared 69 tamsulosin-treated patients to 138 controls; found no significant differences in rates of stone passage, surgical intervention or adverse effects.(13) Participants were in the 2nd or 3rd trimester, limiting generalizability. Both studies had small sample sizes and retrospective designs, which, unlike randomized trials, are vulnerable to confounding by indication (i.e. those selected to receive tamsulosin may have differed from those not selected in other ways that could affect outcomes). Both temporizing interventions (ureteral stent or nephrostomy tube) and definitive intervention with ureteroscopy are safe in pregnant women with more complicated cases.
Indications for urologic intervention in pregnant women at < 20 weeks’ gestation: Fever or infection, renal dysfunction, stone > 1 cm, single kidney, bilateral obstruction, failure of conservative management, persistent nausea/vomiting, and uncontrolled pain. (2, 6, 10)
Evidence supporting use of ureteroscopy in pregnancy comes from a meta-analysis of 108 pregnant patients that showed complication rates were not significantly different from rates in a meta-analysis of nonpregnant patients.(14) While use of a comparison group is valuable, it is possible that pregnant women selected for the procedure were healthier than the general population of adults undergoing ureteroscopy to whom they were compared.
Consider conservative treatment and spontaneous stone passage for patients with stones <10mm, controlled symptoms, and no indication for urologic intervention; can discharge these patients with strict return precautions if adequate access to Obstetrics/outpatient care.
Avoid NSAIDs for pain; trial acetaminophen, then opioids (other than codeine) if needed.
Given limited quality data for efficacy of tamsulosin in pregnancy but no known adverse effects, and demonstrated benefit in nonpregnant adults, it is reasonable to engage in shared decision making with patients about use of tamsulosin, particularly for 5-10mm stones.
Attempt to include patient’s Obstetrics provider in all decision-making, especially given no definitive guidelines or randomized trials to guide treatment of urolithiasis in pregnancy.
Promptly consult Urology (and Obstetrics) when any indication for intervention (fever, infection, renal dysfunction, stone > 1cm, single kidney, bilateral obstruction, failed conservative management, persistent nausea/vomiting, uncontrolled pain) is present or developing.
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2. Semins MJ, Matlaga BR. Management of urolithiasis in pregnancy. Int J Womens Health. 2013;5:599-604.
3. Meria P, Hadjadj H, Jungers P, Daudon M, Members of the French Urological Association Urolithiasis Committee. Stone formation and pregnancy: pathophysiological insights gained from morphoconstitutional stone analysis. J Urol. 2010;183(4):1412-6.
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11. Wang RC, Smith-Bindman R, Whitaker E, Neilson J, Allen IE, Stoller ML, et al. Effect of tamsulosin on stone passage for ureteral stones: a systematic review and meta-analysis. Ann Emerg Med. 2017;69(3):353-61 e3.
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13. Theriault B, Morin F, Cloutier J. Safety and efficacy of tamsulosin as medical expulsive therapy in pregnancy. World J Urol. 2019.
14. Semins MJ, Trock BJ, Matlaga BR. The safety of ureteroscopy during pregnancy: a systematic review and meta-analysis. J Urol. 2009;181(1):139-43.