JU INSIGHT Screening for Zinner Syndrome in Patients With a Congenitally Solitary Kidney: Lessons Learned

By: E. N. Bearrick, MD, Mayo Clinic, Rochester, Minnesota; D. A. Husmann, MD, Mayo Clinic, Rochester, Minnesota | Posted on: 15 Dec 2023

Bearrick EN, Husmann DA. Screening for Zinner syndrome in patients with a congenitally solitary kidney: lessons learned. J Urol. 2023;210(6):888-898.

Study Need and Importance

Despite the known coexistence of a congenital solitary kidney (CSK) with anomalies of the wolffian ducts (Zinner syndrome), no recommendations exist to screen patients with a CSK for these coexisting abnormalities.

What We Found

We evaluated 121 males who were diagnosed with a CSK at < 20 years of age and were ≥ 20 years of age at their last follow-up. Patients were seen yearly to assess their renal function. Pelvic ultrasounds were performed to screen for wolffian ductal abnormalities at birth and at every year of age divisible by 5. At a median follow-up of 38 years of age, 17% (20/121) developed Zinner syndrome (median age at diagnosis 18 years). The diagnostic yield for screening ultrasound studies is shown in the Table. Lower urinary tract symptoms (LUTS) or cyst-related pain symptoms developed in 60% (12/20). The onset of symptoms is associated with the cyst growth, with 30% (3/10) of patients with a cyst < 5 cm in diameter developing symptoms, compared to 90% (9/10) with a cyst ≥ 5 cm (P = .0198).

Table. Percentage of Positive Pelvic Ultrasound Screening Tests for Zinner Syndrome at the Age of Screening: Males With a Congenital Solitary Kidney

Age at time of screening test

Newborn
(1-3 mo)

5 y

10 y

15 y

20 y

25 y

30 y

35 y

40 y

45 y

50 y

55 y

% Positive tests (No./total No. tests performed)

4.3
(2/47)

0
(0/50)

0
(0/57)

6.6
(5/76)

4.5
(5/110)

0
(0/94)

1.6
(1/71)

0
(0/61)

0
(0/47)

0
(0/13)

0
(0/7)

0
(0/3)

A total of 65% (13/20) of patients with Zinner syndrome were diagnosed by screening ultrasound. The yield for screening tests is highest as a neonate is 4.3% (2/47), and during puberty or early adulthood (15-20 years of age) at 5.4% (10/186). Screening studies performed in early childhood were of low utility, with the syndrome rarely radiologically or clinically manifesting before puberty. Persistent screening > 20 years of age was of little benefit, with a yield of 0.33% (1/296).
Twenty percent (4/20) of patients had both their congenital solitary kidney and the Zinner syndrome incidentally diagnosed on radiographic studies at the ages of 15 (1 patient), 16 (2 patients), and 18 (1 patient) years.
Fifteen percent (3/20) of patients had a negative screening study, 1 at 20 years and 2 at 25 years of age. All developed cyst-related symptoms 2 to 3 years after a negative screening ultrasound. The onset of symptoms is presumably due to progression of a partial ejaculatory duct obstruction, into a complete obstruction secondary to prostatic growth, or ductal edema from inflammation or infection.

In symptomatic patients, 75% (8/12) had abnormal uroflows. Complete urodynamic studies revealed findings consistent with bladder outlet obstruction in 38% (3/8), equivocal for obstruction in 24% (2/8), and detrusor underactivity in 38% (3/8). Cyst excision effectively resolved cyst pain—related symptoms (3/3 patients); however, resolution of LUTS occurred only in patients where the complete urodynamic studies revealed obstruction (3/5 patients).

Limitations

A referral bias to our transitional urology clinic could have impacted our findings.

Interpretation for Patient Care

Screening patients for Zinner syndrome is best conducted at ≤ 20 years of age. Surgical intervention should be considered when cyst growth to ≥ 5 cm in size occurs. Resolution of cyst-related pain symptoms is efficacious with surgical intervention; however, resolution of LUTS is directly associated to urodynamic findings.