The growing uterus of a pregnant woman can sometimes press on one or both ureters, the tubes that move urine from the kidneys to the bladder, and obstruct the flow of urine. When this happens, urine flows back towards the affected kidney and causes distention of the renal pelvis, which is the part of the kidney that connects with the ureter. This condition is called hydronephrosis of pregnancy. Aside from the compression of the growing womb of the pregnant woman, hormonal changes may also contribute to this problem.
Hydronephrosis of pregnancy usually affects the right kidney due to the tendency of the growing uterus to rotate to this side. There are cases, however, where both kidneys are affected. When this happens, and the problem is not treated, kidney failure can occur. Symptoms include weakness, swelling of the feet and hands, and decreased urine output, among many others.
Urine normally flows out of the kidneys under low pressure. When there is an obstruction at a certain area of the ureter, the urine cannot flow normally and tends to back up into the kidney, causing the kidney distention and increasing the pressure in the area. Without proper treatment, this increase in pressure can sometimes cause a renal rupture, which can be a life-threatening situation. Important signs that usually precede a renal rupture include pain between the hips and the ribs, the presence of blood in urine, and low blood pressure.
Common complications of hydronephrosis of pregnancy include infection, kidney stone formation, and damage to the affected kidney due to the pooling of urine in the area. Symptoms of infection include fever, abdominal discomfort, and presence of white blood cells in the urine. Patients may also experience nausea and vomiting.
An abdominal ultrasound is generally used to diagnosis this condition because it does not expose the pregnant woman and her fetus to radiation. Treatment usually includes antibiotics, if there is an infection, and other medications for pain. When these medications do not provide relief to patients, invasive procedures may be required. These include placing a stent in the ureter to keep it open or using a catheter to drain urine out of the kidneys. Some pregnant women may be given a cesarean section or have labor induced if the fetus is already at near term.
During treatment, a medical professional will typically advise the pregnant woman to drink plenty of fluids. She may also be put on bed rest and instructed to lie on the side of the kidney that is not affected.