Editing Stones During Pregnancy (section)

== Urologic Changes in Pregnancy ==

# '''<span style="color:#ff0000">Increased renal blood flow, resulting in (4):'''
## '''<span style="color:#ff0000">Increased glomerular filtration rate''' (by 30-50%) and correspond decrease in serum creatinine and blood urea nitrogen
##*'''<span style="color:#ff0000">Normal ranges of serum creatinine and blood urea nitrogen are ≈25% lower for the pregnant patient'''
## '''<span style="color:#ff0000">Increased filtered loads of sodium, calcium, and uric acid''', causing potentially lithogenic changes of hypercalciuria and hyperuricosuria
##*'''Hypercalciuria is further enhanced by placental production of 1,25(OH)2D3, which increases intestinal calcium absorption and secondarily suppresses PTH'''
##*'''These metabolic alterations in the urine may contribute to the accelerated encrustation of ureteral stents during pregnancy'''
##** As a result of these temporary physiologic changes, a metabolic evaluation is not generally undertaken to determine the cause of the stone disease until after the woman has delivered and returned to her baseline state of health.
##'''<span style="color:#ff0000">Increased filtered loads of urinary inhibitors, such as citrate and magnesium'''
##'''<span style="color:#ff0000">Increased urine output'''
# '''<span style="color:#ff0000">Hydronephrosis/hydroureter of Pregnancy'''
#* '''<span style="color:#ff0000">Due to (2):'''
#*# '''<span style="color:#ff0000">Increased circulating progesterone</span>''', which causes relaxation of ureteral smooth muscle, reducing ureteral peristalsis.
#*# '''<span style="color:#ff0000">Direct compression of the ureters by the gravid uterus'''
#*#* '''Likely the main factor'''
#*#** Women with an altered upper urinary tract in whom the ureter does not cross the pelvic brim, such as those with ileal conduit or renal ectopia, do not experience hydronephrosis during pregnancy
#* '''Right ureter tends to be more dilated than the left'''
#* '''Resolves 4-6 weeks post-partum'''
#'''Stone composition'''
#* A multi-institutional study found that '''74% of stones from pregnant women were composed predominantly of calcium phosphate''' and 26% were predominantly calcium oxalate