Early intervention in severe fetal megacystis can increase survival rate and kidney function

An interdisciplinary team from the University Hospitals Cologne and Bonn have conducted the first prospective study to investigate whether very early intervention in unborn children with congenital lower urinary tract obstruction (cLUTO) can improve their chances of survival and subsequent kidney function. The researchers aim to fundamentally improve the prognosis for this serious disease and ideally spare affected children from dialysis.

In the world’s first prospective study on the implantation of vesicoamniotic shunts in the first trimester, 40 pregnancies with severe fetal megacystis were examined. 75% of children were born alive, and 68% survived their first year of life. Of the 29 survivors who received active treatment, 26 (90%) did not require dialysis during their first year of life, and most showed normal or only slightly impaired kidney function.

The results of the study “Intrauterine shunting for first-trimester fetal megacystis (IUS1st)” are published in The Lancet Child & Adolescent Health. The results underscore the great importance of early diagnosis and innovative treatment strategies for congenital kidney diseases even before birth.

“In cLUTO, the unborn child’s urine flow is blocked. The resulting pressure causes significant overstretching of the urinary tract while still in the womb. The permanently increased pressure can damage the developing kidneys at an early stage. At the same time, there is a lack of amniotic fluid, which consists mainly of fetal urine and is essential for normal lung maturation. Insufficient lung development has therefore often been associated with high mortality after birth,” explains Dr. Stefan Kohl, Specialist at the Department of Pediatric and Adolescent Medicine at University Hospital Cologne.

Previous prenatal interventions in the second trimester of pregnancy, in which the fetal bladder is relieved by means of a vesicoamniotic shunt, have not shown any convincing advantage in terms of kidney function or survival in international studies.

“The strategy examined here starts much earlier: With the help of a novel foldable vesicoamniotic shunt that can be inserted through a smaller needle, the procedure could be performed safely at the end of the first trimester of pregnancy—at a stage when the fetus is about the size of a hen’s egg,” says Dr. Eva C. Weber, Deputy Head of Prenatal Medicine and Fetal Surgery, Department for Obstetrics at University Hospital Cologne.

The results show that fetuses treated at an early stage have a good chance of survival and preserved kidney function—provided that there are no additional severe malformations. Dialysis, which was previously often necessary in this patient group, could be avoided in the vast majority of cases.

“Our aim was to examine whether we could protect the sensitive phase of kidney development by relieving pressure on the urinary tract at a very early stage,” says Dr. Weber. “The results suggest that this approach can lay the foundation for better kidney function later on. If we succeed in stabilizing kidney development at an early stage, we can not only improve survival rates, but also reduce long-term consequences such as the need for dialysis.”

“The change in strategy is based on developmental biology considerations,” explains Professor Christoph Berg, Head of Fetal Surgery at University Hospital Cologne and one of the pioneers of the early shunt program in Cologne and Bonn.

“In early pregnancy, the kidney is in a particularly sensitive phase of development. Experimental studies suggest that prolonged pressure from urinary retention can cause permanent damage to the precursor cells of the kidney. By providing relief at a very early stage, we try to protect this critical phase of kidney development.”

A total of 40 pregnancies with severe fetal megacystis in the first trimester, in which a vesicoamniotic shunt was performed, were included in the prospective study. The pregnancies were enrolled between June 2019 and January 2024. The study reports on the clinical course up to the children’s first birthday. Dr. Weber (prenatal medicine) and Dr. Kohl (pediatric nephrology) are the first authors of this study.

The study is the result of close collaboration between the departments of prenatal medicine, pediatric nephrology, pediatric urology, and neonatology at the University Hospitals Cologne and Bonn. The postnatal development of the children was analyzed systematically and in detail for the first time. This interdisciplinary collaboration is also a central principle of the Centre for Family Health (CEFAM) at University Hospital Cologne, which brings together various disciplines related to pregnancy, birth, and child health.

“Such projects make it possible to provide patients with interdisciplinary support from prenatal findings to long-term care,” concludes Professor Dr. Jörg Dötsch, Director of the Clinic for Pediatric and Adolescent Medicine at University Hospital Cologne.