Kidney Stones and Pregnancy

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One thing you probably have not associated with pregnancy is a kidney stone. The medical term is urolithiasis. This condition occurs when a stone forms in your kidney. Passing the stone from your kidney to your bladder can be very painful, and there is a risk of infection. Although the risk of a kidney stone during pregnancy is low, these stones are becoming more common in women of childbearing age.

There was a time when kidney stones were much more common in men than in women. Today the risk for women is similar to men. In fact, according to a review of urolithiasis in pregnancy, published in the International Journal of Women’s Health, other than reasons related directly to pregnancy, a kidney stone is the most common reason for hospital admission during pregnancy.

Why Pregnancy Could Cause a Kidney Stone

The risk of having a kidney stone during pregnancy is somewhere around one in 200 to 1,500. The risk may be higher if you have had a kidney stone before. Statistics say that about 10 percent of women will have a stone during their lifetime. There are some changes that occur during pregnancy that may increase the chance of forming a stone.

Stones tend to form when urine is more concentrated. During your second or third trimester, your growing baby is pushing on your bladder and decreasing the amount of urine your bladder can hold. This may cause frequent urination, and if you don’t keep up with that fluid loss by drinking more fluid, your urine can become concentrated. Other pregnancy risk factors for stone formation include:

  • Elevated progesterone levels which cause decreased urine flow
  • Increased calcium and vitamin D levels from pregnancy supplements
  • Increased amounts of uric acid, sodium, and oxalate, which all can contribute to stone formation

Kidney stones during pregnancy are rare but you need to be aware of the warning signs. Passing a stone is an obvious warning sign, and you will want to get emergency medical care ASAP. Don’t ignore less urgent signs like pink or blood tinged urine, chills, fever, or increased frequency and painful urination.

What are the Symptoms?

You might develop a kidney stone without having any symptoms until the stone moves or starts passing down your ureter into your bladder. You may also develop symptoms if you get a urinary tract infection due to a stone. Let your doctor or pregnancy care provider know if you get any of these symptoms:

  • Fever or chills
  • Cloudy or bad smelling urine
  • Sharp pain in your belly or side that moves down into your groin area
  • A strong and uncomfortable urge to pass urine
  • Inability to pass urine or pain when passing urine
  • Nausea or vomiting
  • Bloody or blood-tinged urine

Diagnosis and Treatment During Pregnancy

Symptoms of a urinary stone are usually obvious, but some of the diagnostic tests used to evaluate stones are avoided during pregnancy due to radiation exposure, including x-rays, CT scans, and contrast imaging studies. You may need urine and blood tests. As far as an imaging study to find out about the size and location of the stone or stones, a sound wave study (ultrasound) is the usual first choice. If more imaging is needed, an MRI study without contrast may be done.

The first choice for treatment is to allow the stone to pass on it’s own, called a trial of passage. This is considered the safest and best treatment unless you have a complication like an infection, multiple stones, or a very large stone. During the trial period, you will be given extra fluids and you may need some pain control medication.

Trial of passage treatment works in about 70 to 80 percent of cases. However, untreated stones that do not pass can increase the risk of some pregnancy complications, especially premature labor. For this reason, a stone that does not pass is usually removed during a surgical procedure called ureteroscopy.

During this procedure, which can be done under spinal or general anesthesia, a thin scope is passed up into the bladder, up the ureter, and into the kidney. The stone is then broken up and removed. This procedure is generally safe during pregnancy and considered to be less risky than leaving the stone in the kidney.

Bottom Line

Kidney stones during pregnancy are rare but you need to be aware of the warning signs. Passing a stone is an obvious warning sign, and you will want to get emergency medical care ASAP. Don’t ignore less urgent signs like pink or blood tinged urine, chills, fever, or increased frequency and painful urination. In most cases, this condition is successfully treated during pregnancy without any danger to you or your baby.

Christopher Iliades
Dr. Chris Iliades is a medical doctor with 20 years of experience in clinical medicine and clinical research. Chris has been a full time medical writer and journalist since 2004. His byline appears in over 1,000 articles online including EverydayHealth, The Clinical Advisor, and Healthgrades. He has also written for print media including Cruising World Magazine, MD News, and The Johns Hopkins Children's Center Magazine. Chris lives with his wife and close to his three children and four grandchildren in the Boston area.

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