Kidney Stones and Pregnancy: Risks, Symptoms & Safe Treatment

How common are kidney stones in pregnancy?

Kidney stones occur in about 1 in 500 to 1 in 1,500 pregnancies. While not extremely common, they are important because they can cause significant morbidity for both mother and fetus. The incidence has been rising, likely due to increasing rates of obesity, diabetes, and changes in dietary habits. Stones are most commonly diagnosed in the second and third trimesters (weeks 20‑36). Interestingly, pregnancy itself increases stone risk due to physiological changes: increased urine calcium excretion, urinary stasis (dilated ureters from progesterone), and reduced urinary citrate.

Risks to mother and baby – why prompt care matters

Kidney stones in pregnancy are not benign. Potential complications include:

• For the mother: Severe pain leading to preterm contractions, pyelonephritis (kidney infection) which can cause sepsis, ureteral obstruction leading to hydronephrosis and kidney damage, and increased risk of pre‑eclampsia.
• For the baby: Preterm labour (pain and infection trigger uterine contractions), low birth weight, and fetal distress. In severe cases, sepsis in the mother can lead to fetal loss.

However, with prompt diagnosis and appropriate management, most women with kidney stones deliver healthy babies at term. At Vivekananda Hospital, we have a dedicated obstetric‑urology team to manage these cases.

Symptoms of kidney stones in pregnancy – often atypical

Pregnancy can mask or alter typical stone symptoms. Pregnant women with kidney stones may experience:

• Flank pain (most common, 70‑80%): Usually dull or colicky, but may be less severe due to ureteral dilation.
• Hematuria (blood in urine): Visible or microscopic.
• Urinary urgency and frequency: Often dismissed as normal pregnancy changes, but may indicate a stone near the UVJ.
• Nausea and vomiting: Can be mistaken for morning sickness, especially if persistent.
• Fever and chills: Indicates pyelonephritis – an emergency.
• Preterm contractions: Pain from a stone can trigger uterine irritability.

Safe diagnosis: ultrasound, MRI, and avoiding CT

Diagnosis is more challenging in pregnancy because ionising radiation (CT scan) is avoided. The preferred modalities are:

• Renal ultrasound (USG KUB): First‑line. Detects hydronephrosis (kidney swelling) and stones >3‑4mm in the kidney or ureter. Sensitivity is only 60‑70%, but it is safe and widely available.
• MRI without contrast (MR urography): Second‑line. Excellent for detecting hydronephrosis and localising stones (as filling defects). No radiation. Sensitivity >90% for ureteral stones.
• Low‑dose CT (if absolutely necessary): Reserved for cases where ultrasound and MRI are inconclusive and clinical suspicion is high. Fetal radiation exposure from a single low‑dose CT is very low (estimated 0.1‑0.3 mGy) but still avoided unless essential.

At Vivekananda Hospital, we use ultrasound as the initial study. If negative but symptoms persist, we proceed to MRI without contrast.

Treatment options: conservative, ureteroscopy, stenting

Treatment depends on stone size, location, symptoms, and gestational age.

Conservative management (first‑line for small stones)

For stones <5‑6mm and no signs of infection or severe obstruction, conservative management is attempted:

• Hydration: 2‑3 litres of water daily.
• Pain control: Paracetamol (acetaminophen) is safe. NSAIDs (ibuprofen) are avoided in the third trimester due to risk of premature closure of the ductus arteriosus.
• Medical expulsion therapy: Tamsulosin is not recommended in pregnancy due to lack of safety data.
• Observation: Most stones will pass with conservative care. However, up to 30% require intervention.

Ureteral stenting (double‑J stent)

For stones causing severe pain, obstruction, or infection, a ureteral stent can be placed under ultrasound guidance (or with minimal fluoroscopy). The stent bypasses the stone, relieving pain and hydronephrosis. It can remain in place until delivery, then the stone is treated postpartum. Stents are safe in pregnancy but require regular changes (every 4‑6 weeks) to prevent encrustation.

Ureteroscopy (URS) with laser

For stones that are large (>8‑10mm), causing persistent symptoms despite stenting, or if the patient prefers definitive treatment, ureteroscopy with laser lithotripsy is safe in pregnancy. Studies have shown no increased risk to the fetus. The procedure is performed under spinal or general anaesthesia, with careful monitoring of fetal heart rate. URS in pregnancy has a stone‑free rate of 85‑95%, similar to non‑pregnant patients.

ESWL, PCNL, and open surgery in pregnancy

ESWL is contraindicated in pregnancy due to potential harm to the fetus. PCNL is avoided because of the need for prone positioning and radiation. Open surgery is reserved for extremely rare cases.

Preventing kidney stones during pregnancy

If you have a history of stones or are at high risk, you can reduce the chance of a stone during pregnancy:

• Hydration: Drink 2.5‑3 litres of water daily. This is the most effective prevention.
• Calcium intake: Do not restrict dietary calcium – it binds oxalate in the gut. Take prenatal vitamins with calcium.
• Low sodium: Limit processed foods and salt. High sodium increases urinary calcium.
• Limit oxalate‑rich foods: Spinach, nuts, beets, chocolate, tea. Pair high‑oxalate foods with calcium (e.g., cheese with spinach).
• Lemon water: Add fresh lemon juice to water to increase urinary citrate.
• Discuss with your doctor: If you have recurrent stones, you may need a 24‑hour urine test before pregnancy to guide prevention.

Interactive FAQ – Kidney stones in pregnancy

Disclaimer: This information is for educational purposes. If you are pregnant and have symptoms of a kidney stone, contact your obstetrician and urologist promptly. For emergencies (fever, severe pain, contractions), go to Vivekananda Hospital immediately.