Kidney Stones During Pregnancy: Symptoms, Risks & Treatment

Kidney stones are hard deposits formed from the amalgamated crystals (such as oxalate, calcium, and phosphate) of the urine. The most common type of kidney stones are calcium stones (1).

The probability of having kidney stones in pregnant women is almost equal to that in non-pregnant women, occurring in one out of 1,500 to 3,000 pregnancies. Most cases manifest during the second and third trimester (2). However, there can be certain conditions that increase the risk for pregnant women.

In this post, we will guide you through the details about kidney stones during pregnancy, including its symptoms, causes, and treatments.

What Are The Causes of Kidney Stones During Pregnancy?

Besides the common causes of kidney stones, including inadequate water intake, obesity, and an unhealthy diet, certain pregnancy-specific risk factors contribute towards its occurrence during pregnancy. These include:

• Lack of fluids: Added pressure on the bladder from the growing fetus causes frequent urination during pregnancy. This may prompt pregnant women to drink fewer fluids to prevent frequently uncomfortable and tiring bathroom breaks. The lack of fluids in the body can cause the accumulation of waste materials in the urine, leading to kidney stones (2).

• High urine pH: During pregnancy, the urine pH increases from 6.1 to 6.3 and above throughout the second and third trimesters. A higher urine pH accounts for more basic and less acidic urine, which forms a favorable environment for calcium phosphate stone formation, most commonly seen in pregnant women (3).

• Increased calcium intake: Besides the recommended additional calcium and vitamin D supplements, pregnant women reabsorb a lot of calcium from the gastrointestinal tract to support the formation of fetal bones and skeleton. These, combined with an increase in the calcium level in the urine during pregnancy, hypercalciuria leads to the formation of calcium stones (4).

• Stagnant urine: The growing fetus and high progesterone level in pregnancy interfere with the normal ureter peristalsis making it difficult for the urine to pass through. This is called hydronephrosis, which is common in pregnancy. However, prolonged stagnant urine can lead to kidney stones (5).

What Are the Signs And Symptoms Of Kidney Stones?

The manifestation of kidney stones in pregnant women is similar to non-pregnant individuals. These include (6):

• Lower back pain, which can ultimately spread to the sides and lower parts of the body.
• Pain and burning sensation during urination.
• Blood in urine.
• Cloudy urine with a foul smell.
• Vomiting tendency or dizziness.
• High temperature, in case the stones get infected.

How Are Kidney Stones Diagnosed During Pregnancy?

The diagnosis for renal calculi in pregnant women may be different from non-pregnant women due to the possible fetal complications. Pregnancy diagnoses for kidney stones include the following tests, often done only if necessary and never in early pregnancy (5):

• Laboratory assessment: Lab assessment involves urine culture to check for urine pH levels and infection-causing microorganisms. Blood samples are taken to test the levels of calcium and the proper functioning of the kidney.

• Ultrasonography (US): The imaging modality, ultrasonography (US), is the first first-line therapy for kidney stones in pregnant women. It may be a transabdominal or transvaginal US depending on the results of visualization.

• Intravenous urography or CT scanning: In cases where ultrasonography failed to produce accurate images of the stones and the severe symptoms continue to persist, intravenous urography (IVU) can help detect kidney stones.
  CT scan may be the last resort, considering the harmful effects of radiation on the fetus. However, by adjusting the radiation dosage, it can detect kidney stones during pregnancy.

What Are The Treatments For Kidney Stones In Pregnancy?

Similar to diagnostic techniques, the treatments for pregnancy kidney stones vary from the treatments for non-pregnant women. These include:

1. Conservative management: Kidney stones measuring less than one centimeter usually pass through the urine. Conservative management involves certain pregnancy-safe pain relief medications and proper hydration to maintain regular urine flow (6).

2. Surgical treatment: When complications, such as vomiting, severe pain, infection, and premature labor manifest, your doctor may recommend active intervention over conservative management. Surgical intervention may also be required if the kidney stones grow larger than one centimeter (5). Surgical treatments for kidney stones recommended during pregnancy include:

• • Nephrostomy tube: In this procedure, a tube called the nephrostomy tube is inserted into the kidney to drain and collect the urine into a bag placed outside the body. This is carried out when the patient is under general anesthesia (6) (7).

• • Ureteroscopy: A telescopic device called a ureteroscope is inserted through the urethra into the kidney where the stones are located. If the stones are larger in size, they are broken down with a laser and removed. For relatively smaller stones, they are removed as a whole. Following this process, a ureteral stent or tube is inserted into the ureter to ensure the kidney is draining urine normally (6)(8).

• • Lithotripsy: This treatment can be used for pregnant women with larger and persistent renal calculi along with hydronephrosis. In lithotripsy, the stones are broken down using shock waves. The broken-down pieces then pass through with urine (9) (10).

Upon delay in timely diagnosis and treatment, kidney stones may cause preterm birth or hinder normal delivery, thereby risking the baby’s health (2).

What Are The Preventive Measures For Kidney Stones During Pregnancy?

Certain preventive measures that you can adopt to minimize the risk factors for kidney stones include (6):

• Sufficient water intake: Remember to drink plenty of water as it can keep your urine diluted, thereby reducing the risk for kidney stones. Try to use the bathroom often and do not hold in your urine for longer durations, as stagnant urine can lead to the formation of renal calculi.

• Reduced salt intake: A high sodium content can increase urine calcium level. Consume sodium within the recommended 1,500 to 2,300mg per day. This also helps control the blood pressure of the body.

• Healthy diet: Include fruits and vegetables and calcium rich foods to maintain a balance of nutrients in the body. Try to include citrus foods as citrate can help prevent the formation of kidney stones. Avoid excessive consumption of red meat. All of these will help maintain calcium, oxalate, and uric acid levels in the urine.

• Doctor’s consultation: You should not miss any doctor’s appointment and be regular with the tests recommended for early detection of any impending complication.

References

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