(Poster 91) Tamsulosin Use for Symptomatic Nephrolithiasis in 3rd Trimester Pregnancies

Objectives: Symptomatic nephrolithiasis (SC) is the most common non-obstetric indication for hospital admission in pregnancy patients, yet optimal management remains undetermined and with use of tamsulosin as a medical expulsive treatment (MET) remaining controversial. This study sought to determine the effectiveness of tamsulosin as MET in 3rd trimester pregnancies complicated by SC.

Methods: We conducted a multi-center, prospective observational study from 7/2022 to 4/2025 and included all pregnant women diagnosed with SC requiring inpatient treatment with gestational ages ranging from 28 0/7 through 40 0/7 weeks-gestation. All patients were placed on IV fluid hydration and morphine for analgesia. Patients where superinfection was determined/suspected were given IV ceftriaxone daily. When MET was performed, tamulosin monotherapy was included as a covariate. All cases of SC were confirmed with renal ultrasonography and successful stone expulsion (SSE) confirmed via urine straining. The primary outcomes included length of hospital stay (LHS) as well as SSE, need for surgical management, and progression to sepsis in cases of superinfection, as discrete events. Patients with preexisting hypertensive disease or allergies to tamulosin were excluded. Medication choice was determined by physician clinical assessment.

Results: The study included 729 patients diagnosed with SC, with 144 patients diagnosed with superinfection. 305 patients were given tamulosin for MET. Baseline demographic factors were not significantly different. Patients who received tamulosin had higher rates of SSE overall (89.8% v. 68.6%, p=0.004) with a 37% (RR=1.37, 95% CI 1.23-1.51, p=0.002) increased likelihood in adjusted models. Patients receiving tamulosin also had a shorter LHS (1.3 v. 2.4 days, p=0.021 and a 19% (RR=0.81, 95% CI 0.69-0.92, p=0.033) decreased risk in adjusted models. No differences were noted among the superinfection group including progression to sepsis.

Conclusions: Tamulosin for MET may be beneficial for patients in 3rd trimester pregnancies complicated by SC.