© Springer International Publishing Switzerland 2015
David A. Schulsinger (ed.)Kidney Stone Disease10.1007/978-3-319-12105-5_1111. Pregnancy and Stones: Stubborn Stone Situation
(1)
Division of Pediatric Urology, Johns Hopkins School of Medicine, The James Buchanan Brady Urological Institute, Baltimore, MD, USA
(2)
Department of Urology, Stony Brook Medicine, Stony Brook, NY, USA
Simple Stone Facts
1:1,500 pregnant women present with stones, however the risk of stone disease is not increased due to pregnancy.
The majority of stones (66 %) will pass spontaneously during pregnancy.
Evaluation and management of a pregnant woman with urolithiasis can be extremely challenging.
Radiation exposure to the fetus should be minimized.
Urinary tract infections must be treated promptly to prevent pre-term labor.
Drainage of the obstructed kidney is the primary goal when infection, intractable pain, and/or intolerance to oral hydration and nutrition are present.
PCNL and ESWL are contraindicated during pregnancy.
Introduction
When a pregnant patient presents with a stone, many will declare that it feels like a double delivery! Some women will swear that the “delivery was easier and less painful than passing my stone.” Fortunately, the incidence of pregnancy and stones is no greater than the general population, with a 1:1,500 risk. Pregnancy and nephrolithiasis can pose diagnostic and therapeutic challenges during different stages of the pregnancy. The purpose of this chapter is to review urolithiasis and pregnancy, with an understanding of the symptoms, different types of work up and various treatment options to manage you and your fetus during this period.
Anatomic Factors
The dynamic anatomy and physiology of a pregnant woman along the course of her pregnancy can make the diagnosis of urolithiasis more difficult than her non-pregnant counterpart. The physiological dilation of the ureter begins at 6–10 weeks of gestation and continues until 4–6 weeks following delivery. Pregnant women often have swelling of the kidney and ureter, called hydroureteronephrosis, due to compression of the ureter by the uterus. This is more common on the right, as the uterus tends to lean to the right side. Additionally, increased circulating levels of progesterone reduce the peristalsis (contractions) and relax the smooth muscles of the ureter. Increased urine production can also cause dilation of the ureters and renal pelvis. If obstruction of the kidney occurs due to compression of the ureter by the gravid uterus, renal colic symptoms can develop. It can be challenging to distinguish renal colic from a passing stone.
Metabolic Factors
An elevated level of vitamin D during pregnancy increases urinary calcium excretion causing hypercalciuria, seemingly increasing the risk of urolithiasis. However, this increase in urinary calcium is counteracted by an increase in urinary magnesium and citrate, inhibitors of calcium stone formation. In addition, an increase in glycosaminoglycans and acidic glycoproteins inhibit oxalate stone formation. There is also an increase in the glomerular filtration rate (GFR) and renal plasma flow (RPF), increasing the urine fluid output.
These opposing factors explain why pregnancy is not associated with an increase risk of stone formation when compared to non-pregnant patients.
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