Kidney stones, also known as renal lithiasis, are a condition that can occur during pregnancy, causing concern for the mother. In this article, we will explore the specific challenges faced by pregnant women with kidney stones and provide essential guidelines for their management.
Is lithiasis or kidney stones common during pregnancy?
The formation of kidney stones, or lithiasis , is called lithogenesis and is due to a combination of physicochemical and anatomical factors that lead to an increase in the concentration of salts in the urine, which then precipitate and form stones. During pregnancy, hormonal changes and alterations in the urinary system can be related to stone formation.
The incidence of urinary stones in pregnancy is around 8 per 1000 pregnancies , a figure similar to that observed in the general female population. Clinical manifestations of kidney stones in pregnancy are more frequent in the second and third trimesters , with an approximate distribution of 16% in the first trimester, 42% in the second, and 42% in the third. The size and location of the stones do not differ from those observed in non-pregnant women.
Symptoms and Diagnosis of Kidney Stones During Pregnancy
The most common clinical presentation is lower back pain (up to 95%). Renal colic is the second most frequent cause of abdominal pain during pregnancy and the most frequent non-obstetric cause of hospital admission.
Other symptoms that may indicate the presence of kidney stones include:
- Blood in the urine or hematuria (second most frequent symptom)
- Increased urinary frequency (which can be confused with the physiological frequency of pregnancy) or
- Urinary infections.
It is therefore crucial to be alert to these symptoms and, if they appear, it is imperative to seek medical attention.
The diagnosis of urinary stones in pregnancy is limited by restrictions on the use of radiation to avoid effects on the fetus. The preferred test is ultrasound, which allows direct visualization of the stone, assessment of the degree of renal dilation, and other indirect signs of obstruction. Another test to consider is magnetic resonance imaging (MRI ), which does not emit ionizing radiation. While it does not visualize the stone itself, it does provide indirect information such as renoureteral dilation and the level at which it occurs. It can also detect other causes of abdominal pain. Its use is limited by the time required to perform the test, its high cost, and restricted accessibility.
Specific considerations of pregnancy
Managing kidney stones during pregnancy presents unique challenges. As previously mentioned, we have limitations on the use of radiological tests that emit ionizing radiation to protect fetal health, especially during the first trimester. Furthermore, certain medications and invasive procedures must be avoided. Therefore, treatment planning must be meticulous to avoid compromising maternal and fetal health.
Treatment of lithiasis in pregnancy
In 80-90% of cases, conservative treatment (fluid therapy and analgesia) constitutes the first therapeutic step, since the evolution of renal colic in pregnant women is usually favorable, with up to 70-80% spontaneous expulsion of the lithiasis.
The indications for interventional treatment in pregnancy are:
- Febrile urinary tract infection
- Acute obstructive renal failure.
- Severe hydronephrosis.
- Patients with a single kidney and obstruction or refractory symptoms (uncontrollable pain).
The first step in this interventional treatment is urinary diversion via placement of a double-J stent or nephrostomy. Sometimes it is possible to postpone specific stone treatment until after delivery. However, poor tolerance and the high frequency of catheter encrustation may necessitate treatment of kidney stones during pregnancy.
In these circumstances, ureteroscopy is the technique of choice. There is a higher risk of complications in the third trimester due to the anatomical changes characteristic of advanced pregnancy; therefore, it is recommended to perform the procedure in the second trimester.
Managing kidney stones in pregnant women requires close collaboration between the urologist and the obstetrician . The medical team must ensure a proper balance in making informed and personalized decisions for each case. The treatment of kidney stones and their potential complications must be based on safety criteria for both the fetus and the mother.
Prevention of kidney stones in pregnancy
Prevention is essential in patients with a history of urinary stones before pregnancy and, in general, in all pregnant patients. The following is recommended:
- Abundant hydration to achieve a diuresis rate of 2-2.5 liters in 24 hours.
- Avoid dietary restrictions and the systematic use of calcium supplements.
In short, kidney stones during pregnancy not only present clinical challenges but also require special considerations for fetal well-being . With a multidisciplinary approach and tailored preventive measures, this condition can be effectively addressed and managed. Treatment at urology centers with extensive experience in endourological surgery is recommended for the follow-up of urinary diversions and the definitive treatment of kidney stones, whether during or after pregnancy, with the ultimate goal of ensuring the best possible health for both mother and unborn child.
