Computed tomographic characterization of urinary stones in patients with urolithiasis from Southeast Mexico

Abstract

Urolithiasis (UL) is a severe public health concern in southeastern Mexico. Computed tomography (CT) is the first-line diagnostic method for patients with suspected UL. The present study aimed to characterize stones in the entire urinary system using CT and to contribute to personalized treatment in patients with UL. Patients >18 years of age with suspected UL were enrolled. Characteristics of UL included stone size, location (kidney, ureters, and bladder), composition of the stone in Hounsfield units (HU), presence of staghorn stone(s), and obstructive uropathy. Patients were stratified according to sex and age to determine whether stone size and HU were dependent on hormonal factors in females and on prostatic hyperplasia in males. The Mann-Whitney U test was used to compare median values. Frequencies are expressed as percentages and were analyzed using the Mantel-Haenszel chi-squared test. A total of 1150 patients were included in this study, of whom 744 (64.7 %) had UL in only 1 anatomical location in the urinary system, and 406 (35.3 %) had stones in ≥2 anatomical locations. Localization and stone size differed between males and females (p < 0.05). Additionally, males exhibited differences in HU (p = 0.024) and frequency of obstructive uropathy (p = 0.10) when stratified according to age (≤50 and > 50 years). In addition, females exhibited statistical differences in HU (p = 0.010) and kidney stone size (p = 0.047) dependent on age (≤47 and > 47 years). In conclusion, findings suggest that HU and stone size differ in different anatomical structures of the urinary system. In addition, differences in stone size and composition may be associated with age and sex.

Keywords: CT scan; Hounsfield units; Mexican population; Stone size.

Fig. 1

Scheme of the sample selection.

Fig. 2

Characteristics of the stones according to the specific anatomic structure from patients with UL. (A) Stone size expressed in millimeters. (B) Composition of the stones expressed in HU. Males: right kidney (n = 97); left kidney (n = 86); right ureter (n = 21); left ureter (n = 26); bladder (n = 12). Females: right kidney (n = 205); left kidney (n = 172); right ureter (n = 31); left ureter (n = 32); bladder (n = 5). Staghorn stones were excluded.

Fig. 3

Comparison of the stone size and HU by different segments of the urinary system between males and females. Males: right upper renal collector (n = 20); right middle renal collector (n = 25); right bottom renal collector (n = 52); upper third of the right ureter (n = 6); middle third of the right ureter (n = 8); bottom third of the right ureter (n = 7); left upper renal collector (n = 13); left middle renal collector (n = 21); left bottom renal collector (n = 49); upper third of the left ureter (n = 7); middle third of the left ureter (n = 3); bottom third of the left ureter (n = 16); bladder (n = 12). Females: right upper renal collector (n = 29); right middle renal collector (n = 58); right bottom renal collector (n = 120); upper third of the right ureter (n = 12); middle third of the right ureter (n = 5); bottom third of the right ureter (n = 14); left upper renal collector (n = 33); left middle renal collector (n = 47); left bottom renal collector (n = 92); upper third of the left ureter (n = 14); middle third of the left ureter (n = 5); bottom third of the left ureter (n = 13); bladder (n = 5).

figs1

Supplementary Figure S1. Comparison between Staghorn stones located in kidneys. (A) Stone sizes expressed in millimeters. (B) Composition of the stones expressed in HU. Males: right kidney (n=8); left kidney (n=4). Females: right kidney (n=35); left kidney (n=11).

figs2

Supplementary Figure S2. Comparative analysis according to anatomical structures and age in male patients with UL. (A) Stone size expressed in millimeters. (B) Attenuation of the stones expressed in HU. Age ≤ 50 years old: kidney (n=182); ureters (n=33); bladder (n=4). Age > 50 years old: kidney (n=123); ureters (n=14); bladder (n=8).

figs3

Supplementary Figure S3. Comparative analysis according to anatomical structures in female patients with UL. (A) Stone size expressed in millimeters. (B) Attenuation of the stones expressed in HU. Age ≤ 47 years old: kidney (n=315); ureters (n=40); bladder (n=3). Age > 47 years old: kidney (n=299); ureters (n=23); bladder (n=2).