Hydronephrosis is a medical term used for dilation of kidney as a result of too much buildup of urine inside it. Mild hydronephrosis during pregnancy is normal physiological phenomenon. Majority of pregnant women may have mild to moderate swelling of kidney. This occurs due to gradual enlargement of uterus which compresses the structures of urinary system such as the uereter and bladder.
The condition is also referred by medical fraternity as maternal hydronephrosis. One or both the kidneys can dilate, but usually dilation is often more on the right kidney especially among women pregnant for the first time.Although asymptomatic in many pregnant women, hydronephrosis can become symptomatic and if left untreated can cause urinary tract infection, sometimes endangering mother and fetus. Nevertheless, in vast majority cases of hydronephrosis gradually resolves after pregnancy.
What Causes Hydronephrosis In Pregnancy?
There are two etiologies postulated for hydronephrosis during pregnancy. One is hormonal while the other obvious is mechanical pressure of the growing uterus size. Hormones play significant role during pregnancy. It has its effect on many organs including uterus. The primary hormones responsible for such changes are progesterone, estrogen and prostaglandins. Progesterone is responsible for relaxation of smooth muscles during pregnancy.
As the size of fetus inside the uterus increases, the smooth muscles of uterus have to relax to accommodate the fetus. The uterus now grows beyond its pelvic space. It puts pressure on the utreter, a connecting tube between kidney and bladder through which urine passes into the bladder. This mild obstruction causes back pressure resulting in buildup of urine in kidney and eventually dilation.
There is increased blood flow in the renal territory during pregnancy. It accentuates the compression from the growing uterus on the ureter. Often if women has stones in the renal system this may increase the chance of hydronephrosis when she is pregnant.
Most often gestational hydronephrosis occurs in second trimester of pregnancy.
Signs And Symptoms Of Hydronephrosis In Pregnancy
Hydronephrosis in pregnancy may present with symptoms in some women, while others may remain asymptomatic. This will depend on the whether the swelling is acute or progressive. There is increased possibility of urinary tract infection in such cases.
Here are important symptoms of hydronephrosis that may be present in a pregnant woman:
- Severe pain in flank, back and abdomen. Due to anatomical position of right ureter, pain is often felt on the right side.
- Along with pain there is associated vomiting and nausea.
- Painful urination.
- Recurrent urinary tract infection.
- Colicky pain.
- Fever due to infection.
- There may be swelling in legs.
- The pregnant woman has to frequently visit washroom due to increased urge for passing urine.
- Chest pain.
- Shortness of breath.
- Passage of blood in urine.
Treatment Of Symptomatic Hydronephrosis In Pregnancy
Many pregnant women may not need any treatment if hydronephrosis is mild. It usually resolves after pregnancy within few weeks or months. However, some women with severe symptoms of hydronephrosis may need medical attention. Most cases are resolved conservatively.
Symptoms are alleviated by giving rest to the woman on a tilted bed with the head end raised by 10 to 20 degree on a wooden block. The woman lies in semi prone position keeping the affected side up. This allows the gravid uterus to fall forward, taking the away mechanical pressure from the ureters.
If kidney stone is blocking the urine pathway, laser is used to break the stone. Sometimes stent may be placed in the ureter for free flow of urine and reducing the dilation in the kidney.