Safe discharge parameters for patients with isolated antenatal hydronephrosis
Introduction
Since the introduction of routine fetal ultrasonography in the 1980s, many anomalies are readily detected prenatally. Of these, approximately 20% represent genitourinary anomalies [1]. Antenatal hydronephrosis (ANH) is detected in about 1–5% of pregnancies [2], [3], [4]. The challenge with this increased detection lies in distinguishing those patients who require stringent follow-up and potential surgical correction from those who will never suffer any clinical consequences, knowing that 60% of ANH is transient and physiologic [2]. ANH caused by pathology is 10–30% from uretero-pelvic junction obstruction (UPJO) and 10–30% from vesico-ureteral reflux (VUR). Other causes such as uretero-vesical junction obstruction (UVJO) and posterior urethral valves (PUV) are less common [5]. Many groups have defined worrisome parameters, without clearly defining those patients who do not need to continue to be followed. We aim to determine parameters that will allow the clinician to safely discharge a patient born with a diagnosis of isolated ANH.
Section snippets
Patients
A retrospective chart review was performed on patients referred to the Children's Hospital of Orange County (CHOC) for hydronephrosis, between 2010 and 2012. The 652 patients referred were filtered for diagnosis of ANH. The inclusion criteria required at least two postnatal ultrasounds with images available for interpretation by the authors. Exclusion criteria were postnatally diagnosed hydronephrosis, insufficient number of postnatal ultrasounds, known neurogenic bladder or duplicated renal
Results
Of the 186 patients included, 113 were categorized in the APD of less than 10 mm group and 73 in the APD of 10 mm or greater group. The renal units followed the same trend, with 228 and 80 in each respective group. Patient and renal unit characteristics for each group are summarized in Table 1, Table 2, respectively. Of the patients, 154 were male (258 male renal units) and 32 were female (50 female renal units), giving a male to female ratio of 5:1. Of the patients, 65% had bilateral ANH, and
Discussion
Patients with a diagnosis of ANH are referred to urologists in great numbers because of increased detection. The follow-up regime for these patients is unclear as there are no guidelines on the frequency and duration of ultrasonography. To complicate things, there are several variations of the definition of ANH, but the one from Corteville et al. ranks amongst the more prudent. According to those authors, ANH is defined as an APD of 4 mm before 33 weeks of gestation or 7 mm after 33 weeks [7].
Conclusion
An initial postnatal APD of 10 mm or greater does not necessarily predict surgery, but patients in this group with a SFU grade 3–4 merit follow-up. However, of greater use, all patients with an APD of less than 10 mm, especially those also with a SFU grade 1–2, can be safely discharged as early as after 2 years of follow-up, as they will most likely not be burdened with complications. Although this study may not be able to eliminate all risk with certitude, the benefits of minimal follow-up in
Conflict of interest
None.
Funding
None.
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