and Spencer W. Beasley2
(1)
Department of Urology, Royal Children’s Hospital, Melbourne, Australia
(2)
Paediatric Surgery Department Otago, University Christchurch Hospital, Christchurch, New Zealand
Abstract
There are sections on the vomiting neonate, dysuria and loin pain and how to collect a urine specimen. We discuss the significance of proven urinary tract infection and have sections on hypertension, wetting and haematuria.
There is marked variation in the presentation and clinical features of infection of the urinary tract. Neonates and infants usually present with general symptoms not specific to the urinary tract, whereas in the older child, although general features may be present, there are clinical features suggestive of a urinary tract problem (Table 14.1). This means that urinary tract infection can present in a number of ways that are described below.
Table 14.1
Presentation of urinary tract infection
1. General features |
Vomiting |
Lethargy or irritability |
Refusal to feed |
Failure to thrive |
Fever |
Toxicity |
2. Specific features |
Dysuria and frequency |
Abdominal pain |
Loin pain |
Wetting |
Haematuria |
The Vomiting Neonate
Vomiting is extremely common in the neonate and may be of little significance (e.g. minor feeding problems, mild gastro-oesophageal reflux) or serious (e.g. meningitis). Urinary tract infection is one serious cause of sepsis in the infant, and thus it shares with other infections the general features of fever, lethargy or irritability; refusal to feed; malaise; and vomiting. These are general signs of sepsis, and, as in any search for infection, the urinary tract should be excluded by looking for white cells or bacteria in the urine. This can be achieved by obtaining a bag specimen or suprapubic aspirate of urine.
Dysuria and Frequency
Dysuria denotes pain in the urethra on voiding and should be distinguished from intra-abdominal pain on voiding, which is discussed below. In the female, the discomfort is perineal, and in the male, it is felt as a sharp burning sensation in the penis or glans. The pain persists for a short period after completion of micturition. The severity of pain may cause involuntary interruption of micturition, allowing only the passage of small volumes of urine at one time. The small child may scream at the commencement of voiding and then be seen to ‘hold back’. In this situation, severe pain may produce urinary retention with overflow incontinence, and the bladder will be palpable in the lower abdomen.
Frequent passage of small volumes of urine is known as ‘frequency’. It may be caused by overflow incontinence but is more commonly the result of the sensation of imminent voiding or ‘urgency’, which occurs in urinary tract infection when the bladder becomes inflamed: A small increase in urine volume triggers reflex bladder emptying. The child finds these impulses difficult to suppress and has ‘accidents’.
Micturition may cause pain in the lower abdomen if there is inflammation of the pelvic peritoneum in the absence of urinary tract infection (e.g. pelvic appendicitis). It is mandatory, therefore, to identify the site and nature of the pain since dysuria, which refers to urethral pain alone, should not be confused with abdominal pain during micturition.
Where a history of dysuria and frequency has been established, further questioning is directed at ascertaining the presence of haematuria or of cloudy or offensive urine. Cloudy precipitates can be present in normal urine at the end of voiding and are of no consequence, and there is no doubt that normal urine has a characteristic odour. However, opaque urine throughout the stream (due to white blood cells and bacteria) and a strong unpleasant odour can be valuable signs of infection even in the absence of dysuria or frequency. Indeed, children with recurrent infections often are able to recognize the infection in this way before other symptoms develop.
Loin Pain
The kidneys lie in the retroperitoneum protected by the posterior abdominal wall muscles and lower ribs. Inflammation of the kidney and renal pelvis produces pain in the loin which may radiate around the flank to the ipsilateral iliac fossa or testis (Fig. 14.1). If the bladder is inflamed as well, there may be suprapubic pain. In pyelonephritis, the collecting system and renal parenchyma become inflamed causing severe loin pain and systemic signs of sepsis and toxicity. The patient is febrile, anorexic, tachycardic and appears flushed and unwell. There is loss of the normal concavity of the renal angle (Fig. 14.2) and scoliosis to the affected side (Fig. 14.3). Gentle percussion of the renal angle is extremely painful (Fig. 14.4) and will cause the patient to jerk the spine in extension. Tenderness anteriorly is less marked but does make palpation of the kidney difficult.
Fig. 14.1
Radiation of loin pain to the abdomen and scrotum
Fig. 14.2
Assessment of fullness of the renal angle: view from above looking down the patient’s back
Fig. 14.4
Percussion of the renal angle with the back of a clenched fist to test for tenderness
Examination and culture of the urine confirms the presence of infection. Plain x-ray of the abdomen will show whether a stone is present, and ultrasound of the kidney may show dilatation of the renal pelvis or swelling of the kidney. In rare instances, where there is infection of the urinary tract proximal to complete obstruction of the ureter or pelviureteric junction, microscopy of the urine may show little evidence of white cells or bacteria and can be misleading.
Collecting a Specimen of Urine
A clean midstream specimen of urine is difficult to obtain in a young child and is unreliable unless supervised. Obtaining a catheter specimen of urine is uncomfortable, time-consuming and runs the risk of introducing infection into the bladder and of damaging the urethra. Furthermore, it is not as reliable as a suprapubic aspiration and, for this reason, is used infrequently. A bag collection of urine is the least reliable technique because of contamination from the perineum and is only significant if the specimen produces no growth. Where culture of a midstream urine specimen produces a pure growth of >105 organisms/ml, infection is considered to be present. Where a mixed growth of organisms is obtained, the significance becomes less certain, and collection of a second specimen is indicated.
Suprapubic Needle Aspiration
Suprapubic needle aspiration is the most reliable method of obtaining urine in an infant. It relies on the intra-abdominal position of the infant bladder attached to the umbilicus and on the small size and capacity of the pelvis (Fig. 14.5). The technique is simple but attention to detail is important (Fig. 14.6). When full, the bladder can be percussed in the lower abdomen or readily palpated in the relaxed infant and may extend as far as the umbilicus. Local anaesthetic cream (e.g. ‘EMLA’) is applied to the suprapubic area and covered with a plastic dressing (e.g. ‘Tegaderm’) for half an hour. The child is given extra fluids during this period to fill the bladder. The cream is then removed and the lower abdomen and external genitalia are thoroughly swabbed with antiseptic solution. A 23-gauge needle attached to a 2-ml syringe is introduced perpendicular to the skin in the midline just above the pubis. It is often helpful to place the index and middle fingers of the left hand on either side of the point of puncture to make the skin taut. The needle is introduced with a quick controlled movement enabling the resistance as it pierces the skin and then the bladder to be felt. Once the bladder has been entered, 1–2 ml of urine is aspirated. The needle is then withdrawn quickly from the skin, and the syringe sent directly to the laboratory or the urine transferred to a sterile urine container for immediate transfer to the laboratory. Delay between collection of the specimen and inspection by the microbiologist should be avoided to prevent overgrowth of contaminating organisms.
Fig. 14.5
The full bladder in an infant is an intra-abdominal organ
Fig. 14.6
The technique of suprapubic needle aspiration of urine. (a) Percuss the bladder in the lower abdomen and apply local anaesthetic cream. (b) Swab the suprapubic region with antiseptic solution. (c) Introduce the syringe perpendicular to the skin just above the pubic bone, and aspirate urine. (d) Put specimen into a sterile container, label with the patient’s identification number and immediately send it to the laboratory
Bag Specimen of Urine
The sterile collection bag is attached to the perineum by an adherent watertight rim after the skin has been cleaned with a mild antiseptic. As soon as the infant or child has passed urine, the bag is removed and the contents immediately placed in the refrigerator or sent to the laboratory for culture. Contamination of the urine by perineal organisms may make interpretation difficult unless culture shows no bacterial growth or a mixed growth of <103 organisms/ml. This indicates no urinary tract infection. A colony count between 103 and 105 organisms/ml may indicate urinary infection or merely represent contamination. Hence, a bag specimen of urine is best used to exclude an infection and should not be used where infection is suspected strongly.
Midstream Urine
This technique can be used in children of 4 years or greater and is appropriate for the routine collection of urine. A midstream urine specimen is obtained because the few bacteria which colonize the urethra are washed out at the commencement of micturition. This method of collection is best in the circumcised male. To minimize contamination in the uncircumcised male, the prepuce should be retracted to expose the glans, and in the female, the labia should be parted (Fig. 14.7). Midstream urine collection is not applicable to younger children because they are unable to initiate and control voiding effectively, and it may be difficult for them to pass an adequate volume on demand.
