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Q&A with Hans Pohl, M.D., on the future of pediatric urology

December 14, 2021

Hans Pohl, Division Chief, Urology

The Urology team at Children’s National Hospital is led by Hans Pohl, M.D., and includes seven other fellowship-trained pediatric urologists and three nurse practitioners. Dr. Pohl has experience in treating patients with spina bifida and bladder exstrophy, in addition to the other more common diagnoses and in using laparoscopy to perform surgery through minimally invasive techniques.

Here, Dr. Pohl tells us more about the department he is leading and what it means for the future of pediatric urology patients at Children’s National.

What excites you most about current research in the field of urology?

The most cutting-edge research these days pertains to understanding the complex and diverse role played by bacteria in the urinary tract. We previously thought the urinary tract is sterile but that turns out to not be the case. Just like the friendly bacteria living in our bodies, there are bacteria that live within our urinary tracts. It is thought that when the normal function of the urinary tract is disrupted, the balance of healthy to unhealthy bacteria is disrupted. Our faculty at the Children’s National Urology Division are looking at urinary tract infection (UTI) from various aspects. Michael Hsieh, M.D., is investigating the role of bacteria in causing inflammation; Daniel Casella, M.D., has investigated how a drug called varenicline might reduce inflammation in infected kidneys; and Briony Varda, M.D., will be investigating the socioeconomic factors affecting how people living with spina bifida manage their urinary tracts and UTIs. By looking at UTIs at all levels from bacteria factors to host factors to treatment we will understand better how to reduce the impact of a very common problem on human beings.

What are some of the most valuable changes or advancements for the program you hope to see in the next couple of years?

I believe that our next step in program evolution will focus on improving the quality of life of children with urination abnormalities and UTIs. Everyone has experienced that their child has urinary symptoms at some point during childhood, some also have UTIs. Pediatric urologists have learned that normal lower urinary tract function is critically important in reducing a child’s risk for a UTI. Even if a child does not have UTIs, there can be significant social stigma amongst a child’s peers when loss of urine control happens.

What makes the Urology Division at Children’s National unique from other programs in the country?

We have grown considerably over the past several years, adding to our faculty surgeons with complimentary skills outside of the operating room. For instance, we have pediatric urologists who are also basic scientists, translational scientists, systems scientists, a clinical informaticist and minimally invasive surgeons. These varied qualities create a dynamic group of people who bring diverse perspectives to treating patients’ problems and generating creative solutions. We believe that our democratic process of complex care management where all surgeons can openly think about how to optimize patient management is unique. Patients don’t get one opinion from their surgeon, they get ten.

Predicting surgery risk through single diuretic renogram

June 14, 2021

In a new study published in the Journal of Pediatric Urology, Aaron Krill, M.D., urologist at Children’s National Hospital and leading author, shows that halftime from a single initial diuretic renogram in children with antenatally detected UPJO is predictive not only of worsening future drainage, but also of future surgical repair (pyeloplasty).

The findings of a new study show promising results that will help to further subdivide the indeterminate drainage range and will help practitioners identify those children at increased risk for worsening drainage and future surgery.

So far, we know that spontaneous resolution of antenatally detected kidney obstruction, also known as ureteropelvic junction obstruction (UPJO), is relatively common. However, it can take several years and require frequent surveillance ultrasounds and diuretic renograms before patients reach a clinical outcome.

The study, which published in the Journal of Pediatric Urology, and was led by Aaron Krill, M.D., urologist at Children’s National Hospital, shows that halftime (T1/2) from a single initial diuretic renogram in children with antenatally detected UPJ obstruction is predictive not only of worsening future drainage, but also of future surgical repair (pyeloplasty).

“Among infants with UPJO, 52 to 79% can be expected to undergo spontaneous improvement,” Dr. Krill said.

Initial nonoperative management has become the standard of care for cases with indeterminate drainage patterns with preserved differential renal function (DRF). Diuretic renography has traditionally been the gold standard for diagnosis and surveillance of this condition. Identification of patients with very good drainage who can safely be discharged and those with very poor drainage who require early surgical repair has never been difficult. However, patients with indeterminate drainage have posed a unique diagnostic and therapeutic problem. Previously published ranges for indeterminate drainage were either too wide or too narrow to be clinically useful.

In the study, recent data shows a five-year surgery-free survival probability for patients with t1/2 of 5-20, 21-40 and 41-60 minutes to be: 79.7%, 46.7% and 33.3%. This suggests that patients with t1/2 of more than 21 minutes are at moderate to high risk of requiring surgery within the first five years of life while those with t1/2 20 minutes or less are at relatively low risk.

“This would allow us to concentrate our efforts appropriately on those who are at high risk of progressing to surgery and minimize the burden of testing and that of radiation exposure for children who are at low risk and likely to improve spontaneously,” Dr. Krill added.

Researchers identified patients younger than 18 months at presentation with unilateral, isolated moderate to severe hydronephrosis who underwent diuresis renography from 2000-2016. This group was sub-divided into three T1/2 intervals: 5-20, 21-40 and 41-60 minutes. Endpoints were pyeloplasty and pyeloplasty free survival. Indications for surgery were loss of DRF, worsening T1/2, family preference and/or pain.

“Being told that your newborn has an obstructed kidney and may require surgery in the future is typically a very stressful event for families,” Dr. Krill said. “Now after only a single diuretic renogram, we can provide families with accurate probability estimates of their child’s lifetime risk of surgery and risk of surgery within their first five years. This should allow us to appropriately set expectations and customize our surveillance routine for each patient.”

For decades, Children’s National has been working to refine and standardize diuretic renography. Some accomplishments over the years include establishing the safety of the test in infants, verifying its diagnostic utility, identifying new drainage parameters, and coupling it with machine learning to improve accuracy. This most recent manuscript capitalizes on a large database spanning 20 years of the team’s clinical experience to further improve the ability to predict who will need surgical repair and better counsel our patients.

Other authors include Briony K. Varda, M.D., M.P.H., Nicholas A. Freidberg, Md Sohel Rana, M.B.B.S., M.P.H., Eglal Shalaby-Rana, M.D., Bruce M. Sprague and Hans G. Pohl, M.D.

Reflections on Seminars in Pediatric Surgery December 2020

December 18, 2020

Marc Levitt, M.D., served as guest editor of a special December Seminars in Pediatric Surgery dedicated to the care and treatment of anorectal malformations.

By Marc Levitt, M.D., chief of the Division of Colorectal and Pelvic Reconstruction at Children’s National Hospital

I was honored to serve as the Guest Editor on the topic of “Anorectal Malformations” in the prestigious Seminars in Pediatric Surgery Volume 29, Issue 6, December 2020.

We had 64 contributing authors from 12 countries; Australia, Austria, Germany, Ghana, Italy, Israel, the Netherlands, Nigeria, Spain, South Africa, the United Kingdom and the United States, and 12 U.S. colorectal collaborating programs; Children’s National, Boston Children’s, Children’s Mercy, Children’s Wisconsin, C.S. Mott Children’s, Cincinnati Children’s, Nationwide Children’s, Nicklaus Children’s, Omaha Children’s, Primary Children’s, Seattle Children’s, and UC Davis Children’s.

There were eight authors from the Children’s National team; myself, Colorectal Director Andrea Badillo, M.D., Colorectal Program Manager Julie Choueiki, MSN, RN, Surgical Center Director Susan Callicott, Katie Worst, CPNP-AC, Grace Ma, M.D., Chief of Urology Hans Pohl, M.D., and Chief of Gynecology Veronica Gomez-Lobo, M.D.

The series of articles included in this collection illustrate new techniques and ideas that over time have made a dramatic and positive impact on the care and quality of life of children who suffer from colorectal problems. With an integrated approach to the care of this complex group of patients, great things can be achieved. As we endeavor to advance this field, we need to always remember that, as Alberto Pena, M.D., often said, “it is not the unanswered questions, but rather the unquestioned answers that one must pursue.”

In my own article on advances in the field, a 2021 update, I reproduce a piece by my daughter, Jess Levitt, who wrote something applicable to the care of children with colorectal problems, with the message that helping to create order is vital to improve a somewhat chaotic medical process traditionally available for the care of complex care. Her essay is reproduced here:

“A” must come before “B,” which must come before “C,” everybody knows that. But what if the Millercamp’s of this world did not have to sit next to the Millerchip’s when it comes to seating arrangements? Can Pat Zawatsky be called before Jack Aaronson when the teacher is taking attendance? Do those 26 letters that make up all the dialogue, signs, thoughts, books, and titles in the English-speaking departments of the world need their specific spots in line? Everyone can sing you the well-known jingle from A to Z, but not many people can tell you why the alphabet is the way it is. For almost as long as humans have had the English language, they have had the alphabet. The good ole ABCs.

However, the alphabet represents the human need for order and stability. I believe that the same thinking that went into the construct of time and even government went into the alphabet. Justifiably, lack of order leads to chaos. Knife-throwing, gun-shooting chaos, in the case of lack of governmental order. Listen to me when I tell you that there is absolutely no reason that the alphabet is arranged the way that it is. Moreover, the alphabet is simply a product of human nature and how it leads people to establish order for things that do not require it.

Now I know this sounds crazy but bear with me. Only if you really peel away the layers of the alphabet will you find the true weight it carries. People organized the letters of our speech into a specific order simply because there wasn’t already one. Questioning this order will enlighten you on the true meaning of it. Really dig deep into the meaning behind the social construct that is the alphabet. Short and sweet as it may be, the order of the ABCs is much less than meets the eye. There is no reason that “J” should fall before “K!” Understand this. Very important as order is, it is only a result of human nature. What’s next? X-rays become independent of Xylophones in children’s books of ABCs?

You know what the best part is? Zero chance you even noticed that each sentence in this essay is in alphabetical order.

Her literary contribution inspired me to do something similar. Take a look at the list of articles in this Seminars edition:

Creating a collaborative program for the care of children with colorectal and pelvic problems. Alejandra Vilanova-Sánchez, Julie Choueiki, Caitlin A. Smith, Susan Callicot, Jason S. Frischer and Marc A. Levitt
Optimal management of the newborn with an anorectal malformation and evaluation of their continence potential. Sebastian K. King, Wilfried Krois, Martin Lacher, Payam Saadai, Yaron Armon and Paola Midrio
Lasting impact on children with an anorectal malformations with proper surgical preparation, respect for anatomic principles, and precise surgical management. Rebecca M. Rentea, Andrea T. Badillo, Stuart Hosie, Jonathan R. Sutcliffe and Belinda Dickie
Long-term urologic and gynecologic follow-up and the importance of collaboration for patients with anorectal malformations. Clare Skerritt, Daniel G. Dajusta, Molly E. Fuchs, Hans Pohl, Veronica Gomez-Lobo and Geri Hewitt
Assessing the previously repaired patient with an anorectal malformation who is not doing well. Victoria A. Lane, Juan Calisto, Ivo Deblaauw, Casey M. Calkins, Inbal Samuk and Jeffrey R. Avansino
Bowel management for the treatment of fecal incontinence and constipation in patients with anorectal malformations. Onnalisa Nash, Sarah Zobell, Katherine Worst and Michael D. Rollins
Organizing the care of a patient with a cloacal malformation: Key steps and decision making for pre-, intra-, and post-operative repair. Richard J. Wood, Carlos A. Reck-Burneo, Alejandra Vilanova-Sanchez and Marc A. Levitt
Radiology of anorectal malformations: What does the surgeon need to know? Matthew Ralls, Benjamin P. Thompson, Brent Adler, Grace Ma, D. Gregory Bates, Steve Kraus and Marcus Jarboe
Adjuncts to bowel management for fecal incontinence and constipation, the role of surgery; appendicostomy, cecostomy, neoappendicostomy, and colonic resection. Devin R. Halleran, Cornelius E.J. Sloots, Megan K. Fuller and Karen Diefenbach
Treating pediatric colorectal patients in low and middle income settings: Creative adaptation to the resources available. Giulia Brisighelli, Victor Etwire, Taiwo Lawal, Marion Arnold and Chris Westgarth-Taylor
Importance of education and the role of the patient and family in the care of anorectal malformations. Greg Ryan, Stephanie Vyrostek, Dalia Aminoff, Kristina Booth, Sarah Driesbach, Meghan Fisher, Julie Gerberick, Michel Haanen, Chelsea Mullins, Lori Parker and Nicole Schwarzer
Ongoing care for the patient with an anorectal malfromation; transitioning to adulthood. Alessandra Gasior, Paola Midrio, Dalia Aminoff and Michael Stanton
New and exciting advances in pediatric colorectal and pelvic reconstructive surgery – 2021 update. Marc A. Levitt

The first letter of each article forms an acrostic of the word “COLLABORATION” which is the secret sauce behind any success in the field of pediatric colorectal care.

Urinary bacteria in spinal cord injury cases may tip balance toward UTIs

January 17, 2019

Patients with spinal cord injuries nearly universally have bacteria present in their urine regardless of whether they have a urinary tract infection.

The fallout from spinal cord injury doesn’t end with loss of mobility: Patients can have a range of other issues resulting from this complex problem, including loss of bladder control that can lead to urine retention. One of the most serious implications is urinary tract infections (UTIs), the most common cause of repeat hospitalization in people with spinal cord injuries, explains Hans G. Pohl, M.D., associate chief in the division of Urology at Children’s National Health System.

Diagnosing UTIs in people with spinal cord injuries is trickier than in people who are otherwise healthy, Dr. Pohl explains. Patients with spinal cord injuries nearly universally have bacteria present in their urine regardless of whether they have a UTI. It’s unclear whether these bacteria are innocent bystanders or precursors to UTIs in patients who don’t yet show symptoms. And although antibiotics can wipe out this bacterial population, these drugs can have undesirable side effects and frequent use can promote development of antibiotic-resistant bacteria.

Although clinical dogma has long promoted the idea that “healthy” urine is sterile, Dr. Pohl and colleagues have shown that a variety of bacteria live in urine, even in people without symptoms. These microorganisms, like the intestinal microbiome, live in harmony with their hosts and may even help promote health. However, it’s unclear what this urinary microbiome might look like for patients with spinal cord injury before, during and after UTIs.

To start investigating this question, Dr. Pohl and co-authors recently reported a case study they published online Sept. 21, 2018, in Spinal Cord Series and Cases. The case report about a 55-year-old man who had injured the thoracic segment of his spinal cord—about the level of the bottom of his shoulder blades—in a skiing accident when he was 19 was selected as “Editor’s Choice” for the journal’s October 2018 issue. The patient had a neurogenic bladder, which doesn’t function normally due to impaired communication with the spinal cord. To compensate for this loss of function, this patient needed to have urine removed every four to six hours by catheterization.

Over eight months Dr. Pohl, the study’s senior author, and colleagues collected 12 urine samples from this patient:

One was collected at a time the patient didn’t show any symptoms of a UTI
Nine were collected when the patient had UTI symptoms, such as bladder spasticity
Two samples were collected when the patient had finished antibiotic treatment for the UTI.

The researchers split each sample in half. One part was put through a standard urinalysis and culture, much like what patients with a suspected UTI would receive at the doctor’s office. The other part was analyzed using a technique that searched for genetic material to identify bacteria that might be present and to estimate their abundance.

The researchers found a variety of different bacteria present in these urine samples. Regardless of the patient’s health status and symptoms, the majority of these bacterial species are known to be pathogenic or potentially pathogenic. By contrast, this patient’s urine microbiome appeared to largely lack bacterial species known to be either neutral or with potentially probiotic properties, such as Lactobacillus.

All of the bacteria that grew in culture also were identified by their genetic material in the samples. However, genetic sequencing also identified a possible novel uropathogenic species called Burkholderia fungorum that didn’t grow in the lab in five of the samples. This bacterium is ubiquitous in the environment and has been identified in soil- and plant-based samples. It also has been discovered in the respiratory secretions of patients with cystic fibrosis, in patients with a heart condition called infectious endocarditis, in the vaginal microbiota of patients with bacterial vaginosis, and in the gut of patients with HIV who have low T-cell counts. Dr. Pohl says it’s unclear whether this species played an infectious role in this patient’s UTI or whether it’s just part of his normal urine flora.

“Consistent with our previous work, this case report demonstrates that rather than healthy urine being sterile, there is a diverse urine bacterial ecosystem during various states of health and disease,” Dr. Pohl says. “Rather than UTIs resulting from the growth or overgrowth of a single organism, it’s more likely that a change in the healthy balance of the urine ecosystem might cause these infections.”

By monitoring the relative abundance of different bacteria types present in the urine of patients with spinal cord injury and combining this information with a patient’s symptoms, Dr. Pohl says doctors may be able to make more accurate UTI diagnoses in this unique population.

In addition to Dr. Pohl, study co-authors include Marcos Pérez-Losada, Ljubica Caldovic, Ph.D., Bruce Sprague and Michael H. Hsieh, M.D., Children’s National; Emma Nally, Suzanne L. Groah and Inger Ljungberg, MedStar National Rehabilitation Hospital; and Neel J. Chandel, Montefiore Medical Center.