Asymptomatic MICRO-HAEMATURIA (AMH)
Haematuria is a commonly encountered problem in general practice.
It presents with visible (gross) haematuria, or more commonly as asymptomatic micro-haematuria (AMH).
Asymptomatic micro-haematuria (AMH) is most often detected during routine health-screening, or on follow-up for patients with diabetes or hypertension by primary care physicians. The prevalence of AMH is about 5% to 20% of general population. As AMH has no symptom, it’s significance is often ignored by physicians and patients alike. Studies have shown that up to 5% of AMH is caused by genito-urinary malignancy. Hence AMH significance must not be under-estimated as it can be an early “red-flag” sign of a serious underlying disease, and prompt investigation and treatment can provide a better outcome for the patient.
Definition of micro-haematuria
A simple urine dipstick test has a very high sensitivity (90%) of detecting micro-haematuria, but it lacks specificity due to its high false positive rate of 35%. Hence the confirmatory test of AMH is a Urine Microscopy. The criteria for AMH for urine microscopy can vary from laboratory to laboratory, but they generally fall in the range of above 3 to above 15 red blood cells per high power field (rbcs/hpf).
Hence, the accepted definition of AMH is a properly collected urine specimen which shows significant number of red blood cells in urine microscopy on at least two separate occasions. When such criterion is met, it is recommended that the patient is thoroughly investigated.
Aetiology of AMH
The aetiology of AMH are numerous and can be broadly classified into GLOMERULAR and NON-GLOMERULAR causes.
Glomerular causes are due to medical disease of the renal glomeruli and its tubules e.g. glomerulonephritis. It can be diagnosed with a phase contrast microscopy which shows a predominantly dysmorphic red blood cells. It is usually accompanied with proteinuria in the urine. Glomerular causes of AMH is less common than non-glomerular causes, and it is usually investigated and managed by a renal physician.
On the other hand, non-glomerular causes of AMH is more common and sometimes termed surgical cause of haematuria. The causes of non-glomerular AMH can be due to benign causes e.g. BPH or UTI, to serious life-threatening causes e.g. urothelial carcinoma or renal cell carcinoma.
The approach to the investigation of AMH involves the complete examination of the urinary tract from the renal papilla to the urethral meatus. Anatomically it can be divided into investigation of the Upper urinary tract and the Lower urinary tract.
Investigation of the Upper Urinary Tract
The upper urinary tract is defined by the urinary tract from the kidney to the ureteric orifice. An imaging modality is the first line investigation of the upper urinary tract. A CT Urography is the best modality as it gives the most information of any pathology along the upper tract. Alternatively, and Ultrasound of the Kidneys which has lower sensitivity and specificity would suffice for patients with very low risk.
Investigation of the Lower Urinary Tract
The lower urinary tract includes the entire bladder and the urethra. A Cysto-urethroscopy by a Urologist is the preferred method of assessing the lower urinary tract. Often, a minimally traumatic Flexible Cystoscopy is used and it can be performed in an Outpatient or Day Surgery setting. The Cystoscopy is necessary as it is high sensitivity in detecting very small or flat bladder cancer lesion, which would otherwise have been missed by just an ultrasound scan or a CT urography. Cystoscopy also has added advantage that a biopsy can be performed if a lesion is visualized during the examination.
Urine cytology is very sensitive at detecting high grade urothelial cancers as these tumours has greater tendency to shed cancer cells in the urine. In some centres, it is routinely used to screen AMH patients for urothelial malignancy. However, its lower sensitivity in detecting lower grade urothelial cancers limits its usefulness.
It is noteworthy that even with thorough investigations above, in about 50% of AMH patients, no apparent cause can be found. Hence, the patient need to be counselled that the investigations are not necessary to elucidate the cause of AMH, but its role is to exclude serious causes of AMH like a urinary stone or urothelial cancer.
Asymptomatic Microhaematuria (AMH) which is often seen by primary care physician has a small but nevertheless significant risk of a serious underlying disease of the urinary tract. An early and full evaluation by a Urologist would help to re-assure the patient, and if serious disease e.g. malignancy or urinary stone is found, its early detection and treatment would greatly benefit the patient.
A Specialist’s Point of View – Written by Dr Ong Chin Hu
Dr Ong Chin Hu
BSc(Med), MBBS(Hons), MRCSEd, MMed(Surgery), FAMS(Urology), FEBU (Europe), FRCS (Urol) (UK)
Dr Ong Chin Hu graduated with MBBS Honours from the University of New South Wales, Sydney, Australia in 1997. He stayed on and worked in Australia upon graduation, and completed his Basic Surgical Training with the Royal Australasian College of Surgeons (RACS) in 2001.
Thereafter, he further his Advanced Surgical Urology training at Alexandra Hospital (AH) and National University Hospital (NUH), Singapore, completing with distinction in 2008. He won the European Board of Urology (EBU) book prize and College of Surgeons’ Gold Medal in 2008 for his achievement.
Dr Ong underwent his fellowship training on Uro-oncology and Reconstructive Urology under distinguished Urologist, Professor Urs Studer at the Bern University Hospital, Switzerland in 2009. And in 2010, he worked as the Laparoscopic Uro-oncology & Stone Surgery Fellow at Nepean Hospital (teaching hospital of University of Sydney) in Sydney, Australia under Professor M Khadra. Dr Ong was the Japanese Urological Association (JUA) International Foundation Scholar in 2012, for which he had further training in Robotic Surgery under Professor Masato Fujisawa at Kobe University Hospital, Japan.
Dr Ong is a qualified Urologist with Fellowship recognition from various international institutions including the Academy of Medicine, Singapore, the European Board of Urology, and the Royal College of Surgeons’ of Glasgow.
Dr Ong is currently a visiting Urologist to Mount Elizabeth Hospital (Orchard & Novena), Gleneagles Hospital, Mt Alvernia Hospital and Parkway East Hospital. He is also the assistant renal transplant surgeon with the National Organ Transplant Unit (NOTU).
Dr Ong speaks fluent Bahasa Melayu/Indonesia, English, Mandarin and Hokkien.
Areas of Urology practice for Dr Ong includes:
- Screening and treatment of haematuria
(blood in urine)
• Screening and treatment of abnormal PSA
(prostate cancer screening)
• Urinary tract stones/kidney STONES
• Prostate, Kidney, Bladder and Testicular CANCERS
• Minimally invasive, Endoscopic & Robotic
• Male & Female Urinary tract symptoms
e.g. BPH, LUTS, Voiding dysfunction.
• Urinary tract Infections (Male & Female) e.g. recurrent UTIs, Prostatitis
• Male Sexual Dysfunction e.g. erectile dysfunction, premature ejaculation.
• Sexually Transmitted Disease
• Male andropause (late onet hypogonadism)
• Male Circumcision (above 12 year-old), Vasectomy etc.
#07-56 Mount Alvernia Medical Center Blk D
820 Thomson Road, Singapore 574623
Tel: (65) 6255 1005 Fax: (65) 6255 1006
Email: [email protected]