Hydronephrosis In Pregnancy: What It Is, Causes & Treatment

✔ Research-backed

Hydronephrosis refers to the swelling of the kidney due to the accumulation of urine, and the condition is known to affect 90% of pregnant women (1). In this condition, the kidney swells up as the urine is unable to pass through it and reach the bladder due to urinary tract obstruction or blockage.

You must consult your doctor immediately if you notice hydronephrosis symptoms to prevent further complications. Read on to know more about hydronephrosis, including its causes, signs and symptoms, treatment, and prevention options.

In This Article

What Is Hydronephrosis?

Hydronephrosis in pregnancy is not a disease per say. It is a structural condition which typically occurs in one kidney or when chronic, affects both the kidneys. The failure of normal drainage of urine from the kidney to the urinary bladder can result in the swelling of either one of the kidneys or both. This condition commonly refers to hydronephrosis. It may happen as a normal physiological variant or an underlying illness.

When the swelling affects one of the kidneys, it is called Unilateral Hydronephrosis. While, when both the kidneys are simultaneously affected, the disorder is called Bilateral Hydronephrosis.

protip_icon Quick fact
Hydronephrosis during pregnancy becomes more prominent on the right side. However, the condition is not found in those whose ureters do not cross the pelvic brim (6).

Maternal Hydronephrosis

A condition of developing hydronephrosis during pregnancy, due to the presence of the fetus within the womb, is maternal/gestational hydronephrosis. The asymptomatic dilation of the renal calyces, the renal pelvis and the upper two-thirds of ureters, during pregnancy results in this typical condition.

Also referred to as gestational hydronephrosis, it is also associated with the common trouble of urinary tract infection in pregnant women. Therefore, it is estimated, around 90% of pregnant women may suffer from some form of hydronephrosis or urinary retention during pregnancy. An existence of hydronephrosis due to some pathological condition prenatally worsens the disorder (1).

Symptoms Of Hydronephrosis

Chest pain may be a symptom of hydronephrosis during pregnancy

Image: Shutterstock

Here are a few symptoms of hydronephrosis during pregnancy. However, in some cases, there will be no symptoms at all. Symptoms depend on whether the swelling occurs acutely, progressively or more gradually.

  • Acute flank pain or pain in the back and abdominal region
  • Nausea and vomiting
  • Constant urinary tract infection with painful urination
  • Fever
  • Colicky painiA sudden, intense, spasm-like stomach ache that can strike suddenly and is recurrent.
  • Stains of blood in the urine or hematuria
  • Chest pain
  • Swelling of the legs
  • Increased frequency of urination (2)

Causes Of Hydronephrosis

Kidney stones may be a cause of maternal hydronephrosis

Image: IStock

The hormonal changes during pregnancy involving estrogen, progesterone, and prostaglandin-like agents cause disorders such as hydronephrosis and hydroureteriDilated ureters due to obstruction of urine flow resulting from the blockage of the ureter. (Ureteral Ectasia).

Pregnancy causes generalized relaxation of smooth muscles due to the effect of progesterone. Along with dextro-rotation of the uterus, the incidence of hydronephrosis in pregnant women becomes greater. The growing weight of the uterus in a limited pelvic space can cause pressure over the ureters (pipes that connect the kidney to the urinary bladder), leading to the dilatation of the ureters and hence contributing to the incidence of hydroureteronephrosis. Increasing gestational age and growth of the uterus outside the pelvis can decrease this pressure on the ureters (3).

Similarly, the pregnancy-related hormonal effect can also cause fetal hydronephrosis up to a limited extent. There could be other causes of maternal hydronephrosis too. Kidney stones, blood clots, stricture or scarring of the kidneys, bladder cancer, urethral stricture, etc., are some of the intrinsic causes of maternal hydronephrosis. Similarly, external causes, such as cervical cancer and ovarian vein syndromeiAn unusual syndrome when a dilated ovarian vein leads to an obstruction of the ureters. , and functional causes, such as diabetes and vesicoureteral refluxiA disorder when the urine flows backward via one or both ureters and reaches the kidneys. , may also cause maternal hydronephrosis.

protip_icon Quick fact
In some cases, hydronephrosis (due to blockage and swelling of the kidneys) occurs rapidly, while in others, it develops slowly (2).


  • The gestational hydronephrosis usually occurs in the second trimester. It affects almost 90% of pregnancies by 26 to 28 weeks of gestation.
  • The incidence of ureteral and kidney dilatation is greater in nulliparous patients. (A woman who has not carried the pregnancy beyond 20 weeks is termed nulliparous).
  • Mostly gestational hydronephrosis disappears on its own, without any form of treatment. The ideal period is six weeks after delivery, but sometimes, it may persist longer.

The graphical representation below illustrates the outcomes of a study conducted on 58 expectant mothers experiencing different levels of symptomatic ureterohydronephrosis. The results corroborate that maternal ureterohydronephrosis is a common anatomical modification during pregnancy. Also, its prevalence varies based on gestational age, with a higher frequency observed during the second and third trimesters.

Distribution of hydronephrosis cases according to gestational age

Source: Early diagnosis of maternal ureterohydronephrosis during pregnancy; Experimental and Therapeutic Medicine


An ultrasound scan can help in indentifying the cause of hydronephrosis during pregnancy

Image: Shutterstock

  • Ultrasound scan can help in differentiating physiological hydronephrosis from obstruction secondary to renal stones/calculus.
  • Analysis of urine to determine an infection.
  • Renal function test to detect the proper functioning of kidneys.


The obstetric complications and risks due to gestational hydronephrosis include preterm labor and delivery and pyelonephritisiA bacterial infection of the kidneys. . A very rare but potentially life-threatening complication associated with severe gestational hydronephrosis is a spontaneous renal rupture. It occurs due to increased hydrostatic pressure within the collecting structures that exceeds the holding capacity of the calyceal-renal capsular junctions.

Kidneys with prior damage before pregnancy are more susceptible to suffering from a spontaneous renal rupture. If left untreated beyond a reasonable period, the kidney will permanently fail to function, leading to renal failure (3).

When To Seek Medical Assistance

An incidence of fever, acute pain in the abdomen, traces of blood in the urine, bladder dysfunction, or any other urological complications are all pointers to seek medical help immediately. Hydronephrosis can be fatal in pregnant women with just one kidney. Therefore, even the development of slight symptoms, even in the case of a single kidney, should be brought to the attention of your doctor immediately.

Hydronephrosis In Pregnancy Treatment

The treatment of symptomatic gestational hydronephrosis during pregnancy is carefully performed through different stages. Take a look at them.

1. Most cases with mild symptoms of gestational hydronephrosis with normal renal function can be treated symptomatically. Some of the treatments include anti-spasmodicsiA drug that reduces the contractions and spasms of abdominal muscles. , analgesics, proper hydration, left lateral position while sleeping, and treating urinary tract infection, if any.

2. Draining the urine through a thin catheter inserted into the bladder or directly to the kidney through the skin under local anesthesia relieves the pressure on the kidneys.

3. Treating the underlying cause, which primarily caused the blockage, is the next line of management. A surgery called ureteral stenting usually removes the obstruction. Different causes will have different treatments. For instance, if a large kidney stone triggers hydronephrosis, sound waves or lasers are used to break it (4). In severe cases leading to kidney failure, your obstetrician may suggest dialysis.

Dani Tippet, a first-time mother shares, “My second trimester was one I was looking forward to, as many women enjoy this part of pregnancy most. Unfortunately, I was greeted with excruciating pain caused by a kidney condition called hydronephrosis. I worked through this pain from my 25th week in pregnancy, up until my 33rd week. At that point, my urologist recommended I undergo surgery to relieve the pain and pressure I was experiencing for the safety and comfort of both myself and my baby (i).”


Regular urine tests may help in detecting kidney disorders in pregnancy

Image: Shutterstock

Kidney diseases often have no/mild symptoms. Hence, it can go undetected if not tested at the right time. Early detection and treatment can slow or prevent the progression of kidney disease. A regular urine test and blood test can help us in finding the prevalence of any kidney disorders in pregnancy (5).

Frequently Asked Questions

1. Is hydronephrosis in the fetus serious?

Untreated hydronephrosis may result in complications such as kidney stones, urinary tract infections, and chronic kidney disease (7).

2. Which side does hydronephrosis in pregnancy usually occur on?

Hydronephrosis during pregnancy is more prominent on the right than on the left due to the changes that happen during pregnancy, such as rotation of the uterus and engorgement of the ovarian veins (8).

3. How often should women with hydronephrosis during pregnancy be monitored by a healthcare provider?

The number of times a doctor should monitor a woman with hydronephrosis during pregnancy varies and relies on several factors, such as the individual’s health, the severity of the condition, and the underlying cause. Generally, women with hydronephrosis during pregnancy are monitored regularly to ensure the well-being of the mother and the baby.

Hydronephrosis during pregnancy is common and mostly resolves after childbirth without requiring specific treatment. It refers to the inability of the kidneys to drain the urine. This could be due to the growing fetus taking up space in the abdominal cavity and the changes in the hormone levels. It may cause flank pain, fever, or blood in the urine. It may cause concern if associated with renal stones, urinary tract infections, or other underlying kidney conditions. Discuss with your doctor if you observe any symptoms of hydronephrosis and ensure not to miss prenatal check-ups as they are essential for the early diagnosis.

Infographic: How To Keep Your Kidneys Healthy During Pregnancy?

Pregnancy induces changes in all aspects of kidney functions, including increased glomerular filtration rate and renal plasma flow. Regular prenatal checkups and controlling certain pregnancy complications are necessary to avoid kidney damage. Follow the tips given in the infographic below to promote kidney health during pregnancy.

how to keep your kidneys healthy during pregnancy (infographic)

Illustration: Momjunction Design Team

Key Pointers

  • Hydronephrosis is when the kidney swells due to urine backup, and it is common during pregnancy.
  • Symptoms of hydronephrosis include nausea, vomiting, fever, blood in urine, and swollen legs.
  • Some of the causes of maternal hydronephrosis are hormonal imbalance, kidney stones, blood clots, and diabetes.
  • Hydronephrosis during pregnancy can cause preterm labor and may lead to kidney failure if left untreated.
  • After childbirth, hydronephrosis usually resolves on its own. However, if you experience recurring symptoms, speak to your doctor.

Are you unable to pass urine through your bladder during your pregnancy? You could be suffering from Hydronephrosis. Watch this video to know how specialists cater to you and your unborn child’s well-being.

Personal Experience: Source


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
  1. Maternal Hydronephrosis in Pregnancy.
  2. Hydronephrosis of one kidney.
  3. Hydronephrosis.
  4. Hydronephrosis.
  5. Prevention.
  6. Hydronephrosis in Newborns.
  7. Debasmita Mandal et al.; (2017); Urological disorders and pregnancy: An overall experience.
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Dr. Arpita Chakraborty practices at Bombay Hospital, Mumbai and has eight years of experience in the field of ob/gyn. She has passed her medical training with distinction and bagged gold medals in various subjects. Dr. Chakraborty trained in advanced laparoscopy at Bombay Hospital and did FOGSI Certified Course in Obstetrics Ultrasonography.

Read full bio of Dr. Arpita Chakraborty