Pregnancy Tips: What Is Dilatated Renal Pelvis?

GREAT EXPECTATIONS
By Dr Lai Fon Min
Consultant Obstetrician and Gynaecologist | A Company for Women, Camden Medical Centre
reprinted with permission from "Great Expectations" by Today's Parents magazine

I’VE JUST HAD MY 20-WEEK ANOMALY SCAN AND HAVE BEEN TOLD MY BABY HAS A DILATATED RENAL PELVIS. ALTHOUGH I’VE BEEN REASSURED THIS CONDITION WILL PROBABLY CORRECT ITSELF, I’M WORRIED.

Mild renal pelvic dilatation (swelling of the collecting system in the foetal kidney) occurs in 1 to 3 percent of pregnancies. It is more common in male foetuses. It is usually defined as an antero-posterior diameter of > 5 mm before 24 weeks and > 7 mm after 25 weeks.

Usually the condition will resolve on its own, but worsening renal pelvis dilatation may be due to some underlying problem in the urinary tract like obstruction, or certain abnormalities in formation of the kidney, for example, a duplex kidney or a multicystic kidney. If there is no family history of kidney disease, and there are no other abnormal findings on ultrasound, the outcome in the baby depends on whether the dilatation worsens as the pregnancy progresses.

If there are no other abnormal findings in addition to the dilatated renal pelvis, there is no need to check for chromosomal abnormalities in the foetus.

If the dilatation remains static or is less than 10mm, then an ultrasound scan of the urinary system will be done three to four days after birth. If this is normal, a follow up scan should be repeated one, six or 12 months later.

Unfortunately, the clinical significance of persistent neonatal renal pelvic dilatation is unknown as long-term follow up studies are not available. Even if the dilatation persists, the likelihood of serious urinary tract problems is very low.

If the dilatation is > 10 mm in a follow up ultrasound scan after 28 weeks gestation, your baby will be continued to be monitored closely after birth and other specialized tests of urinary tract function may be necessary.

Source: Pregnancy Tips: What Is Dilatated Renal Pelvis?