- Email: [email protected]
Infantile hypertrophic pyloric stenosis: A fresh approach to the diagnosis
ClinicalRadiol°gY(1983) 34, 51-53 © 1983 Royal College of Radiologists
0009-9260/83/01320051502.00
Infantile Hypertrophic Pyloric Stenosis: A Fresh Approach to the Diagnosis D. W. PILLING
Department of Radiology, Alder Hey Children'sHospital, Eaton Road, Liverpool Infantile hypertrophic pyloric stenosis is a condition occurring in early infancy. The traditional approach to the diagnosis has been clinical, relying on the palpation of a 'tumour' caused by the muscular thickening of the pylorus. In doubtful cases a barium meal is diagnostic. Ultrasound, with the lack of hazards associated with radiation, provides an additional method of investigation which is accurate and will diagnose some cases in which no pyloric tumour is palpable. This will spare infants from a barium meal but there are still cases in which a barium meal will be necessary because a tumour cannot be palpated or demonstrated by ultrasound.
The traditional approach to the diagnosis of infantile hypertrophic pyloric stenosis (IHPS) has relied upon palpation of the pyloric 'tumour', the detection of the tumour being made easier by palpating the abdomen whilst the baby is being fed as this relaxes the abdominal wall and is also thought to make the tumour more prominent due to contraction of the muscle wall of the pylorus. Recently ultrasound has been employed as an adjunct to clinical examination in the difficult cases (Teele and Smith, 1977). Twenty-three per cent of babies with proven IHPS attending Alder Hey Children's Hospital in 1979 had required a barium meal to make the diagnosis. When ultrasound became available in the hospital it was decided to review our approach to the diagnosis of IHPS to determine the role of ultrasound.
obstruction at the pylorus with vigorous peristalsis and gastric dilation or the 'string' sign with indentation of the duodenal bulb by the tumour (Caffey, 1978). The ultrasound findings were not taken into consideration when making a decision about further management. The appearance of a pyloric tumour is shown in Fig. 1. The thickened pyloric muscle is less echo-dense than the normal liver but the centre of the turnout is more echo-dense producing a so-called 'target' lesion. The tumour is usually most easily recognised in the longitudinal scan but can be confirmed in the transverse scan as a rather elongated 'target' lesion. The target lesion is greater than 1.5 cm in diameter.
METHOD All babies presenting in the hospital from April 1980 to March 1981 between the age of 2 and 13 weeks with a history of persistent vomiting suggestive of IHPS were first examined clinically. Regardless of whether a pyloric tumour had been palpated or not infants were then examined by ultrasound of the abdomen. The ultrasound machine used was a Kretz Cornbison 100 real-time sector scanner with 2.5 MHz probe. Pyloromyotomy was then performed if a pyloric tumour was felt. The scanner had no knowledge of the clinical findings whilst scanning. The infants were then treated on clinical grounds either with further observation and examination to detect a pyloric tumour, or subjected to a barium meal to detect a pyloric tumour or exclude other causes of vomiting. The diagnosis of pyloric stenosis on barium meal was considered proven if there was complete
Fig. 1 Longitudinal section to the right of the midline of abdomen. H = head end, F = foot end, WB = water bag (stand-off device), L = liver, K = kidney. Arrows indicate the pyloric tumour.
52
CLINICAL RADIOLOGY
Rarely, a target lesion smaller than this was seen but usually only fleetingly and this has been considered to be a normal pytorus which is about 1 cm in diameter. It was usually easier to identify the lesion using a polythene bag of intravenous fluid coated with ultrasound conducting gel between the probe and the patient's abdomen. The bag was placed on the patient's abdomen with the probe moved over its free surface. Such a stand-off device was found useful for two reasons. Firstly, it enabled the child to settle more easily as the movements of the probe were not so easily felt through the bag and secondly, the superficial parts of the baby's abdomen were more clearly demonstrated as the artefacts seen in the f'trst 1 - 2 cm of the field were eliminated.
Table 2 - Suggested scheme of investigation Vomiting baby
Pytorie turnout felt
No turnout felt
Ultrasound
Turnout seen
I PYLOROMYOTOMY ~
No tumour see1
Turnout seen-~----Barium meal
DISCUSSION Our study has shown that ultrasound is an accurate method of diagnosing the presence of a pyloric tumour. There were no false positives using the criterion of a target lesion larger than 1.5 cm as the lowest limit of size for a pyloric tumour. Table 1 also shows that ultrasound is fairly sensitive as only two of the 26 palpable pyloric tumours were not detected by ultrasound. However, the figures in Table 1 show that the vast majority of the turnouts demonstrated by ultrasound were also palpable, so that the technique does not increase substantially the number in whom pyloric stenosis can be diagnosed without resort to a barium meal. In six patients with proven IHPS at operation the turnout had not been diagnosed by ultrasound. Even in retrospect the reasons for this failure are not certain. The most likely cause for failure is a gassy abdomen in a screaming restless child. Another possible cause of failure may be very tight stenosis of
Table 1 - Analysis of results Total patients scanned IHPS proven at operation IHPS diagnosed by ultrasound
55 32 26
Diagnosed by ultrasound: palable Diagnosed by ultrasound: non-palable
24
2
Palpable pylofic tumour 26 Palpable pyloric tumout demonstrated b y ultrasound 24 Palpable pylotic tumour not demonstrated by ultrasound 2 False negatives False positives
6 0
No tumour seer
Seek other causes of vomiting
the pylorus. The echo-dense centre of the tumour is caused by folds of pyloric mucosa and the recognition of the tumour relies very heavily on recognising this dense centre as the surrounding pyloric tumour is not very greatly different in echo density from the liver. Perhaps almost complete obstruction squashes the pyloric folds and alters the appearances, making the centre of the tumour more difficult to see. Two of our six negative cases had such a tight stenosis that no barium left the stomach during the barium meal and this would support this hypothesis as a possible cause of failure. A further possible cause of failure may be lack of experience of the operator in the early stages of the investigation but there was no evidence to support this. Undoubtedly a higher frequency probe would have improved resolution and this may have decreased the number of false negative examinations. Our experience indicates that the logical flow pattern for investigation is as shown in Table 2. All infants with suspected IHPS should have the abdomen palpated during a feed and if a tumour is not felt but the clinical symptoms and signs strongly suggest the diagnosis then ultrasound should be performed. In these circumstances a turnout will only be demonstrated in about 8.5% of patients but even this small pick-up rate is worthwhile in order to save tile irradiation of a barium meal which would otherwise be necessary.
INFANTILE HYPERTROPHIC PYLORIC STENOSIS coNCLUSIONS 1. The technique of ultrasound is accurate with no false positives, but there were 19% false negatives. 2. Only rarely will a tumour be found on ultrasound when one cannot be felt. 3. Ultrasound is valuable in the diagnosis of other causes of vomiting. One case o f bilateral adrenal haemorrhage was diagnosed and one case o f bilateral hydro-uretero-nephrosis. Neither o f these had been clinically suspected before ultrasound.
53
Acknowledgements. I should like to thank the PhotogIaphic Department at Alder Hey Children's Hospital for their help and Mrs D. Slater for typing the manuscript.
REFERENCES Caffey, J. (1978). Pediatric X-ray Diagnosis, p. 1714. Year Book Medical Publishers Inc., Chicago. Teele, R. L. & Smith, E. H. (1977). Ultrasound in the diagnosis of infantile hypertrophic pyloric stenosis. New England Journal of Medicine, 296, 1149-1150.
0009-9260/83/01320051502.00
Infantile Hypertrophic Pyloric Stenosis: A Fresh Approach to the Diagnosis D. W. PILLING
Department of Radiology, Alder Hey Children'sHospital, Eaton Road, Liverpool Infantile hypertrophic pyloric stenosis is a condition occurring in early infancy. The traditional approach to the diagnosis has been clinical, relying on the palpation of a 'tumour' caused by the muscular thickening of the pylorus. In doubtful cases a barium meal is diagnostic. Ultrasound, with the lack of hazards associated with radiation, provides an additional method of investigation which is accurate and will diagnose some cases in which no pyloric tumour is palpable. This will spare infants from a barium meal but there are still cases in which a barium meal will be necessary because a tumour cannot be palpated or demonstrated by ultrasound.
The traditional approach to the diagnosis of infantile hypertrophic pyloric stenosis (IHPS) has relied upon palpation of the pyloric 'tumour', the detection of the tumour being made easier by palpating the abdomen whilst the baby is being fed as this relaxes the abdominal wall and is also thought to make the tumour more prominent due to contraction of the muscle wall of the pylorus. Recently ultrasound has been employed as an adjunct to clinical examination in the difficult cases (Teele and Smith, 1977). Twenty-three per cent of babies with proven IHPS attending Alder Hey Children's Hospital in 1979 had required a barium meal to make the diagnosis. When ultrasound became available in the hospital it was decided to review our approach to the diagnosis of IHPS to determine the role of ultrasound.
obstruction at the pylorus with vigorous peristalsis and gastric dilation or the 'string' sign with indentation of the duodenal bulb by the tumour (Caffey, 1978). The ultrasound findings were not taken into consideration when making a decision about further management. The appearance of a pyloric tumour is shown in Fig. 1. The thickened pyloric muscle is less echo-dense than the normal liver but the centre of the turnout is more echo-dense producing a so-called 'target' lesion. The tumour is usually most easily recognised in the longitudinal scan but can be confirmed in the transverse scan as a rather elongated 'target' lesion. The target lesion is greater than 1.5 cm in diameter.
METHOD All babies presenting in the hospital from April 1980 to March 1981 between the age of 2 and 13 weeks with a history of persistent vomiting suggestive of IHPS were first examined clinically. Regardless of whether a pyloric tumour had been palpated or not infants were then examined by ultrasound of the abdomen. The ultrasound machine used was a Kretz Cornbison 100 real-time sector scanner with 2.5 MHz probe. Pyloromyotomy was then performed if a pyloric tumour was felt. The scanner had no knowledge of the clinical findings whilst scanning. The infants were then treated on clinical grounds either with further observation and examination to detect a pyloric tumour, or subjected to a barium meal to detect a pyloric tumour or exclude other causes of vomiting. The diagnosis of pyloric stenosis on barium meal was considered proven if there was complete
Fig. 1 Longitudinal section to the right of the midline of abdomen. H = head end, F = foot end, WB = water bag (stand-off device), L = liver, K = kidney. Arrows indicate the pyloric tumour.
52
CLINICAL RADIOLOGY
Rarely, a target lesion smaller than this was seen but usually only fleetingly and this has been considered to be a normal pytorus which is about 1 cm in diameter. It was usually easier to identify the lesion using a polythene bag of intravenous fluid coated with ultrasound conducting gel between the probe and the patient's abdomen. The bag was placed on the patient's abdomen with the probe moved over its free surface. Such a stand-off device was found useful for two reasons. Firstly, it enabled the child to settle more easily as the movements of the probe were not so easily felt through the bag and secondly, the superficial parts of the baby's abdomen were more clearly demonstrated as the artefacts seen in the f'trst 1 - 2 cm of the field were eliminated.
Table 2 - Suggested scheme of investigation Vomiting baby
Pytorie turnout felt
No turnout felt
Ultrasound
Turnout seen
I PYLOROMYOTOMY ~
No tumour see1
Turnout seen-~----Barium meal
DISCUSSION Our study has shown that ultrasound is an accurate method of diagnosing the presence of a pyloric tumour. There were no false positives using the criterion of a target lesion larger than 1.5 cm as the lowest limit of size for a pyloric tumour. Table 1 also shows that ultrasound is fairly sensitive as only two of the 26 palpable pyloric tumours were not detected by ultrasound. However, the figures in Table 1 show that the vast majority of the turnouts demonstrated by ultrasound were also palpable, so that the technique does not increase substantially the number in whom pyloric stenosis can be diagnosed without resort to a barium meal. In six patients with proven IHPS at operation the turnout had not been diagnosed by ultrasound. Even in retrospect the reasons for this failure are not certain. The most likely cause for failure is a gassy abdomen in a screaming restless child. Another possible cause of failure may be very tight stenosis of
Table 1 - Analysis of results Total patients scanned IHPS proven at operation IHPS diagnosed by ultrasound
55 32 26
Diagnosed by ultrasound: palable Diagnosed by ultrasound: non-palable
24
2
Palpable pylofic tumour 26 Palpable pyloric tumout demonstrated b y ultrasound 24 Palpable pylotic tumour not demonstrated by ultrasound 2 False negatives False positives
6 0
No tumour seer
Seek other causes of vomiting
the pylorus. The echo-dense centre of the tumour is caused by folds of pyloric mucosa and the recognition of the tumour relies very heavily on recognising this dense centre as the surrounding pyloric tumour is not very greatly different in echo density from the liver. Perhaps almost complete obstruction squashes the pyloric folds and alters the appearances, making the centre of the tumour more difficult to see. Two of our six negative cases had such a tight stenosis that no barium left the stomach during the barium meal and this would support this hypothesis as a possible cause of failure. A further possible cause of failure may be lack of experience of the operator in the early stages of the investigation but there was no evidence to support this. Undoubtedly a higher frequency probe would have improved resolution and this may have decreased the number of false negative examinations. Our experience indicates that the logical flow pattern for investigation is as shown in Table 2. All infants with suspected IHPS should have the abdomen palpated during a feed and if a tumour is not felt but the clinical symptoms and signs strongly suggest the diagnosis then ultrasound should be performed. In these circumstances a turnout will only be demonstrated in about 8.5% of patients but even this small pick-up rate is worthwhile in order to save tile irradiation of a barium meal which would otherwise be necessary.
INFANTILE HYPERTROPHIC PYLORIC STENOSIS coNCLUSIONS 1. The technique of ultrasound is accurate with no false positives, but there were 19% false negatives. 2. Only rarely will a tumour be found on ultrasound when one cannot be felt. 3. Ultrasound is valuable in the diagnosis of other causes of vomiting. One case o f bilateral adrenal haemorrhage was diagnosed and one case o f bilateral hydro-uretero-nephrosis. Neither o f these had been clinically suspected before ultrasound.
53
Acknowledgements. I should like to thank the PhotogIaphic Department at Alder Hey Children's Hospital for their help and Mrs D. Slater for typing the manuscript.
REFERENCES Caffey, J. (1978). Pediatric X-ray Diagnosis, p. 1714. Year Book Medical Publishers Inc., Chicago. Teele, R. L. & Smith, E. H. (1977). Ultrasound in the diagnosis of infantile hypertrophic pyloric stenosis. New England Journal of Medicine, 296, 1149-1150.