Kidney Stone During Pregnancy – Causes, Symptoms, Treatment and Prevention

Did you know that the most common cause of abdominal pain during pregnancy is urinary stones, also known as Urolithiasis? Though stones during pregnancy are a rare occurrence, correct and proper diagnosis is necessary to ease the pain and prevent early labor. Most of the stones are small enough to pass through the urinary tract, but the larger stones require medical intervention and treatment. Let’s look at all the aspects of this disease especially during pregnancy.

What are kidney stones?

Urinary stones are aggregation of chemical substances dissolved in urine. When the concentration level of these substances reaches a particular point, they crystallize and form stones.  Know more about kidney stone treatment, diagnosis and causes

What physiological changes lead to kidney stones in pregnant women?

Here, is a rundown on the physiological changes, a pregnant woman faces. These changes usually occur in the second trimester and subside after delivery -

• There are some specific changes that occur in the woman’s physiology during pregnancy that may affect the urinary tract leading to increased chances of problems with already present urinary stone(s) or these changes can even increase the chance of formation of new kidney stones.
• Later in pregnancy, the size and position of the uterus can restrict the outflow of urine. The ureters get dilated in pregnancy and may not eliminate urine as efficiently, and this may lead to hydronephrosis (swelling of the kidney). The ureters increase in size (approx. 1 cm) due to increased renal vascular and interstitial volume during pregnancy. The collecting system and ureters also decrease their ability to contract, resulting in dilation and sometimes pain. The big concern of dilation is stagnant urine. If the urine is not fully eliminated, stone or infection can occur. These changes usually occur in the second trimester and subside after delivery.
• Also, during pregnancy, a variety of changes happening with vitamins and minerals can also cause the formation of kidney stones. During this state, the body tends to handle calcium less effectively, thereby leading to onset of kidney stones.
• Urinary tract infection, commonly seen during pregnancy may also contribute to development of kidney stones.
• The need of the body for water also increases during pregnancy. The lack of fluid intake may lead to dehydration and contribute to kidney stone formation.

Typical clinical presentation of kidney stones:

It is commonly mis-diagnosed as appendicitis, diverticulitis (inflammation or colon wall) or placental abruption. The stones occur in the ureter twice as often as in the kidney and affect both ureters in equal frequency. Here are some common symptoms to look out for:

• Renal colic or severe abdominal or flank pain
• Radiating pain to the groin
• Occurrence of nausea and vomiting
• Dysuria or painful and frequent urination
• Haematuria or blood in the urine

If the stone does not pass, it may initiate premature labor, produce intractable pain, cause urinary tract infection or even sepsis, or interfere with the progress of normal labor.

Diagnosis of Kidney Stones during pregnancy

Urolithiasisin pregnancy is often a diagnostic and therapeutic challenge. Approximately 80-90% urinary stones are diagnosed after the first trimester gets over. Here the different ways to diagnose the disease:

• Laboratory Assessment - A urine culture and sensitivity can confirm infection, blood work can check kidney function and increased serum calcium requires further investigation.
• Radiological Diagnosis – It includes Magnetic Resonance Imaging or Magnetic Resonance Urography – the risks from radiation are dependent of fetus age. Obtaining the imaging with lower dose protocols to treat the stone is justified in certain cases. X-rays are absolutely contraindicated as these are more of a risk to the foetus.
• Ultrasonography(US)– It is the first option for diagnosing kidney stones in pregnant women. Only skilled professionals can perform the procedure for both US and doppler US. However, ultrasound does not always show the presence of stones.
• Intravenous Urography or CT scanning – Only if the symptoms persist or symptoms are causing other complex problems, is this option used in pregnant woman.
• Nuclear Renography – A radioisotope is injected into a vein allowing the radiologist to look at the kidneys. It is to check for functional studies.
• MRI has limited utility in such cases.
• Ideally, no ionizing radiation is to be used in the first or second trimesters.

Kidney Stone Disease Treatment & Management

Let’s look at the kidney stone treatment and management during pregnancy.

• Conservative management
  Patient is advised bed rest, adequate fluid intake, and medications to help manage the disease. Most of the stones (70-80%) pass spontaneously with conservative treatment.
• Invasive treatments
  ?Any type of manipulation in the bladder, pelvis, ureter or kidney could result in premature labor. However, necessary treatments include:
  • Stenting - A stent or PCN tube is placed in the ureter. The tube passes the urine lessening the burden on the contraction of the urinary tract. The tube is not removed till end of pregnancy.
  • Extracorporeal Shock Wave Lithotripsy – ESWL uses ultrasonic pulses fragment renal stones. It is totally contraindicated during pregnancy as it can cause fetal damage and death though it is highly recommended for non-pregnant women.
  • Ureteroscopic Stone Removal (URS) - URS is the recommended method for pregnant women where stone removal Is necessary. Holmium is used to fragment stones and is used as an alternative to ESWL.
  • Percutaneous nephrolithotomy (PCNLs) – An access tract is created in the renal collecting system. Though its safety and efficacy are well-established for non-pregnant women, it is not recommended during pregnancy; reasons include general anesthesia and prolonged prone position.

Prevention of urinary stones during pregnancy

Prevention of urinary stones during pregnancy is the key and is the best cure. Here are the simple prevention tips -

• Drink plenty of fluids including water and keep the body hydrated.
• Don’t hold in the urine, even if it means frequent trips to the washroom or toilet
• Reduce intake of high oxalate foods such as nuts, chocolates, dark green leafy vegetables, and berries
• Discuss prophylactic treatment with specialist when planning pregnancy, especially if there is history of kidney stones
• Be physically active and exercise as per doctor’s guidelines
• Instantly consult doctor in case of severe pain in the abdominal area

Kidney stones during pregnancy is difficult to manage as it can lead to obstetric complications and fetal harm. A multidisciplinary team should care for women receiving treatment for kidney stone during pregnancy in India.