Andrew Siegel MD 12/04/2021
A recent entry was an update on kidney stone advances and today’s will cover the topic of kidney stones in pregnant women…certainly not the aggravation a woman with child needs.
Kidney stones can be intensely painful and are often accompanied by nausea and vomiting, making for a horrific experience. Kidney stones do not spare pregnant women and, in fact, the most common reason for pain-related hospitalization during pregnancy is a kidney stone. Pregnancy is certainly burdensome enough without this added insult. Dealing with a stone when pregnant is clearly double trouble, affecting both maternal and fetal wellbeing. The good news is that only a small percentage of pregnant women suffer with symptomatic kidney stones, most of which will pass spontaneously without intervention.
Having a stone during pregnancy poses unique clinical challenges because of the need to minimize the potential risks of radiation and intervention to mother and fetus. It also poses diagnostic challenges because the normal physiological urinary tract changes of pregnancy (fullness and dilation of the ureters) mimic those induced by kidney stones.
Most stone episodes are diagnosed during the second and third trimesters. The most common clinical presentation is flank pain and blood in the urine, often accompanied by nausea and fever. Misdiagnosis is not uncommon, with initial considerations before the correct diagnosis is made of appendicitis, diverticulitis, and placental abruption.
Computerized tomography is the standard for evaluation of kidney stones in non-pregnant patients, but because of the substantial amount of radiation required, it is not recommended imaging for pregnant patients except under extenuating circumstances. Ultrasonography is the first-line imaging study of choice because it does not use radiation that could be problematic to the fetus. Magnetic resonance imaging as well does not use radiation and thus is a second-line study for the evaluation of pregnant patients with kidney stones.
Management of stones in pregnant women requires carefully balancing the risks and benefits of the various means of intervention. Conservative watchful waiting with treatment of symptoms is an excellent approach when there is no infection associated with a stone. This entails hydration, pain medication and anti-nausea medications. Most pregnant patients with stones can be managed conservatively and most will ultimately pass their stones without intervention. Those managed conservatively who fail to pass their stones warrant careful follow-up following delivery with appropriate imaging and management.
30% or so of symptomatic pregnant patients with kidney stones require active intervention. Intervention is appropriate for a pregnant female with a stone if she is experiencing unrelenting pain, unremitting nausea and vomiting, obstruction with an infection, worsening signs of obstruction, high-grade obstruction, obstruction of a solitary kidney, or stones involving both kidneys. Obstetric complications including pre-term labor and pre-eclampsia may provoke intervention. One of the key issues with intervention is that it nearly triples the rate of pre-term labor as compared to conservative management.
Intervention in Pregnant Women with Kidney Stones
Care for pregnant patients who require stone intervention involves a multidisciplinary approach and shared decision making between patient and urologist with input from obstetrics, radiology and anesthesia.
One possibility is a percutaneous nephrostomy tube. This is a small caliber tube (similar to an intravenous tube) placed by interventional radiology through the soft tissues of the flank directly into the kidney via ultrasound guidance. The tube is secured to the skin and connected to a drainage bag and serves to bypass the obstruction and alleviate pain and other symptoms. Potential issues are tube clogging and dislodgment and the need to exchange it for a fresh tube if it needs to be kept in for a prolonged period of time.
Another possibility is a ureteral stent, a small caliber hollow tube about ten inches in length with pigtail-like loops at each end. The stent is inserted into the ureter by a urologist in the operating room using cystoscopy, in which a small scope is passed into the bladder with or without fluoroscopy (dynamic X-ray guidance). The small opening where the ureter enters the bladder is identified and the stent is passed up the ureter beyond the obstruction and into the kidney. When properly seated, one end of the stent lies within the kidney and the other end lies within the bladder. With a stent in place, despite obstruction from a stone, urine will pass from the kidney into the bladder via the stent. The stent is most often left in on a temporary basis until the obstruction can be removed. Potential issues are encrustation and obstruction of the stent requiring exchanges.
A third means of management is ureteroscopy and laser lithotripsy. If needed, ideally it is done during the second trimester to avoid the risks to fetal development during the first trimester and triggering pre-term labor during the third trimester. This procedure is performed by a urologist in the operating room and involves the placement of a narrow scope into the bladder and up the ureter to the level of the stone. A laser is used to fragment the stones and the fragments are removed with a stone basket. Most often a stent is placed and maintained for a short interval after the procedure.
Bottom Line: Kidney stones in pregnant women can be challenging for both patient and managing physician because of diagnostic and treatment limitations. Risks and benefits must be carefully considered for both mother and fetus. Limiting radiation exposure to the fetus is of paramount importance as is avoiding pre-term labor in the mother. Most patients can be successfully managed conservatively, but intervention will be required in about one in three pregnant women with symptomatic stones. Shared decision making is vital in terms of choice of imaging, pain management and treatment.
Wishing you the best of health,
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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery. He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro Area, Inside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States. He is the co-founder of PelvicRx and Private Gym. His latest book is Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families.
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Andrew Siegel MD Amazon author page
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Dr. Siegel’s other books:
PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food
MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health
THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health
Tags: Andrew Siegel MD, kidney stones, nephrostomy tube, pregnancy, ureteral stent, ureteroscopy and laser lithotripsy
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