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Last updated: Lesson of the Month - October 2017…
on 17 Oct 2017

August 2012

Mansoor Ali

Case Presentation

A 70yr old gentleman presented to a district general hospital over the weekend, with shortness of breath, fever and low back ache. He had also been oligo-anuric for several days. He was diagnosed with community acquired pneumonia, dehydration, and likely secondary acute kidney injury (AKI). Near anuria was now noted. Baseline investigations were done (see below) and he was admitted to the intensive care unit for respiratory and renal support

The renal registrar was contacted, who worked at the tertiary care centre nearby, who accepted the patient for transfer to the renal unit when stable, and suggested the team should obtain an ultrasound scan of the renal tract over the weekend, and send off a 'renal screen’. The ITU team sent off some immunology tests as directed (see below) and eventually obtained an ultrasound of the renal tract over the weekend. This suggested both kidneys were mildly enlarged from hydronephrosis, although it was technically difficult due to patient habitus. The patient was given fluid replacement, and was started on antibiotics


Initial Investigations:

  1. FBC – Hb 10.4, WCC 16.2, Plt 228
  2. U&E – Cr 236, Ur 21, Na 145, K 4.9
  3. CRP – 164
  4. CXR – confirmed evidence of pulmonary oedema plus consolidation
  5. Renal immunology screen – ANCA, ANA, Anti-GBM, Complement – all negative
  6. Portable US scan – as above

He was stabilised over the following 48 hours, and transferred to the tertiary care renal unit for ongoing renal support. He recovered well from his presumed infection but still remained dialysis dependent almost 4 weeks from his initial presentation. The patient had some physiotherapy due to constant low back ache and leg weakness which was thought to be due to long in-patient hospital stay. The team became concerned that his renal function was not improving as anticipated. The patient’s history was re-visited, and prior to his admission, he described several months of worsening prostatic symptoms

A repeat USS of the renal tract was organised, and PSA was also sent. Repeat USS renal tract showed severely enlarged, hydronephrotic kidneys, and a dilated urinary tract, with enlarged prostate (this was confirmed on digital rectal examination). PSA was raised at 200pcg/ml and the patient was booked for a CT chest, abdo, pelvis, which unfortunately showed bony metastases, as well as liver and lung metastases. The images from the initial USS at the DGH were reviewed, and were felt to have infact shown moderate hydronephrosis on admission, not minimal hydronephrosis as initially reported

The patient was referred to the urology team, but unfortunately the cancer was too advanced and deemed incurable. The above was discussed in detail with the patient and the family, including the delay in the diagnosis. The patient expressed clearly his wish to be discharged to a hospice under the palliative care team, and he died peacefully 3 weeks later

Discussion

AKI secondary to Obstructive Uropathy

It is important to have a systematic approach when reviewing a patient with AKI. The kidney can be affected by any systemic illness; and diseases of the kidney and urinary tract can present with a number of (often non-specific) symptoms. Obstruction of the urinary tract is not uncommon (especially in men of this age) and important not to miss -as it can be a silent cause of renal impairment. It leads to delayed urinary transit and over time increased intra-tract pressure and impaired renal function. Renal tract USS should be routinely done for all cases of AKI, as obstructive uropathy can be reversible

Who should look after these patients - Urology or Nephrology?

Patients presenting with AKI should be reviewed by nephrologists to ensure initial investigations are completed appropriately, and to help with urgent management. If USS confirms hydronephrosis, urological involvement is warranted for definitive diagnosis and management. If biochemical parameters are severe/worsening (or there are clinical complications of AKI such as pulmonary oedema or acidosis), a renal team should take over of the care with appropriate intervention to resuscitate the patient, including provision of renal replacement therapy

Don’t delay  .. 'Time = nephrons'

Depending on the cause of the obstructive uropathy, it may initially be relieved by something as simple as a urethral catheter (if obstruction is urethral), or may require more complex interventions such as percutaneous nephrostomy

Lessons

  1. Low threshold of repeating a test: It is important to have a low threshold to repeat a test when no explicable cause could be found for a patient’s presentation. In the above case, it would have been appropriate to have repeated the USS much earlier if there was no apparent recovery from AKI following treatment for pneumonia
  2. Should all DGH ultrasounds be repeated? Yes, unless you can personally vouch for the operator that has interpreted the first USS
  3. Revisiting the history: As with almost all diagnoses, the clues are in the history. And when the diagnosis is unclear, revisiting the history with an open mind is essential – this includes a repeat clerking whenever a patient is transferred between hospitals (not simply copying out the initial clerking history!). It may be that relevant information was overlooked, or not asked about during a patient's acute admission, as they may have been too unwell. In this case it is understandable that the admitting team did not ask about the patients' prostatic symptoms, but when the patient was transferred having been stabilised, the receiving team should  have picked his prostatic symptoms earlier - a question as simple as 'have you had any problems passing water recently?' would probably have done
  4. Anuria is very unusual: It only has three common causes: obstruction, vascular catastrophe and occasionally acute severe glomerulonephritis. All three are a.serious and b. potentially reversible. So, early senior involvement is required
  5. Transfer of radiology images: Ensure that the radiological investigations done somewhere else prior to patient transfer are linked to your own radiology department for further discussions in the departmental multidisciplinary meetings. Or where this service is not available, it is important to get a formal report of the investigation faxed or sent across to the accepting team. It is the responsibility of both teams, referring and admitting, to ensure appropriate images are transferred
  6. Check the report/results yourself: Never assume a result is normal, without having checked or seen the report yourself
  7. The 'renal screen': Although it was not significant in this case, the original team were asked to send a 'renal screen'. The team did send some immunological tests, but missed a large number of tests that may have been required. 'Renal screen' is not a particularly helpful term, as it means different things to different people, and clinicians will vary what they request each time. The safest thing to do is to ask the person asking for a 'renal screen' to say exactly what they want

References:

Jurgen Floege , Richard J. Johnson, John Feehally; Comprehensive Clinical Nephrology; fourth edition

Oxford American Handbook of Nephrology and Hypertension

Barbara K Blok, Beatrice Hoffman. Renal Ultrasound; ultrasound guide for emergency physicians



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