Kidney stones, or nephrolithiasis, are an uncommon illness during pregnancy. The majority of stones consist of calcium-containing crystals. As one of the most common causes of abdominal pain in pregnant patients in the second and third trimesters, kidney stones usually pass without the need for treatment. However, since they have been shown to be associated with a higher risk of having premature labor and in general are more difficult to manage during pregnancy, it is important to be aware of other possible treatment options.
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Conservative "Watch and Wait" Therapy
The majority of pregnant women with kidney stones respond well to conservative “watching and waiting” therapy, which includes increasing fluid intake, avoiding too much calcium intake (not over 1000-1200 mg/day), proper pain management and antibiotics if there is an infection. Acetaminophen (Tylenol) provides temporary pain relief, and other pain medications may be prescribed at the discretion of the health care provider. If this does not work, then other procedures may be necessary. Increased pain, the presence of infection or preterm labor especially warrants surgical intervention.
Traditionally, urologists have supported ureteroscopy (breaking up the stone), or the placement of a stent or tube to rapidly drain the affected area around the stone or obstruction, which is discussed further below. A uretoroscopy involves the passage of a thin tube called a ureteroscope up the urinary tract to the stone, which allows a doctor to look at the stone and make a more certain diagnosis. Instruments are then used to remove the stone or break it up. It is becoming widely accepted as a first-line approach, and has been found to be safe and effective during all stages of pregnancy. However, large stones (greater than 1 cm) cannot be treated with this method.
Stent or Tube Placement
A ureteral stent (like a hollow tube) or a nephrostomy tube may need to be placed in the ureter (tubes that carry urine) in order to drain urine and possibly stone particles. Minimal or no anesthesia may be used, and this procedure is usually successful. Replacement of the tubes and urinary discomfort can cause problems. Definitive treatment of the stones can usually be delayed until after delivery.
Open surgery with general anesthesia to remove the stone, and shockwave therapy which to break up the stone, can usually be used in patients who are not pregnant. However, they are not considered to be safe during pregnancy because of risks to the fetus.