An unusual case of a giant fetal facial tumour and review of the literature

We present the case of a pregnant 32-year-old woman who presented with a giant fetal facial tumour at 22 weeks. The mass, initially 4 × 3.5 × 3 cm in size, was largely cystic with a small solid component. It subsequently increased to 9 × 9 × 10 cm. Significant compression effects on the fetal orbit, temple and infratemporal fossa, with potential compression of the optic nerve, were noted on ultrasound and MRI. The cyst required drainage twice in the pregnancy: firstly to reduce the compression effects and secondly to facilitate caesarean delivery. Postnatally, the baby had significant compression and displacement of the craniofacial skeleton from the mass effect. Postnatal histology revealed a diagnosis of a teratoma. This case highlights the complexities and challenges surrounding the diagnosis and management of a giant fetal facial tumour.

How to apply evidence-based practice to the use of artificial intelligence in radiology (EBRAI) using the data algorithm training output (DATO) method

OBJECTIVE

As the number of radiology artificial intelligence (AI) papers increases, there are new challenges for reviewing the AI literature as well as differences to be aware of, for those familiar with the clinical radiology literature. We aim to introduce a tool to aid in this process.

METHODS

In evidence-based practise (EBP), you must Ask, Search, Appraise, Apply and Evaluate to come to an evidence-based decision. The bottom-up evidence-based radiology (EBR) method allows for a systematic way of choosing the correct radiological investigation or treatment. Just as the population intervention comparison outcome (PICO) method is an established means of asking an answerable question; herein, we introduce the data algorithm training output (DATO) method to complement PICO by considering Data, Algorithm, Training and Output in the use of AI to answer the question.

RESULTS

We illustrate the DATO method with a worked example concerning bone age assessment from skeletal radiographs. After a systematic search, 17 bone age estimation papers (5 of which externally validated their results) were appraised. The paper with the best DATO metrics found that an ensemble model combining uncorrelated, high performing simple models should achieve error rates comparable to human performance.

CONCLUSION

Considering DATO in the application of EBR to AI is a simple systematic approach to this potentially daunting subject.

ADVANCES IN KNOWLEDGE

The growth of AI in radiology means that radiologists and related professionals now need to be able to review not only clinical radiological literature but also research using AI methods. Considering Data, Algorithm, Training and Output in the application of EBR to AI is a simple systematic approach to this potentially daunting subject.

Placenta accreta spectrum ultrasound stage and fetal growth

OBJECTIVE

to evaluate fetal growth in pregnancies complicated by placenta accreta spectrum (PAS) and to compare fetal growth between cases stratified by ultrasound stage of PAS.

METHODS

This was a prospective multicenter cohort study of women diagnosed with PAS between January 2018 and December 2021. We grouped participants into cases by ultrasound stage (PAS stage 1-3) and controls (PAS0). Fetal growth centiles at three timepoints with median gestational ages of 21 ± 1 weeks (interquartile range [IQR], 20 ± 1-22 ± 0 weeks), 28 ± 0 weeks (IQR, 27 ± 0-28 ± 5 weeks), and 33 ± 0 weeks (IQR, 32 ± 1-34 ± 0 weeks) and birth weight centiles were compared between cases and controls and between those with PAS stratified by ultrasound stage.

RESULTS

A total of 53 women met inclusion criteria, with a mean age of 37 years (standard deviation, ±4.0 years) and body mass index of 27 kg/m² (standard deviation, ±5.8 kg/m² ). Median (IQR) fetal weight centiles were around the 50th centile at each timepoint, with no difference between groups. The incidence of small for gestational age (birth weight ≤ 10th percentile) and large for gestational age (birth weight ≥ 90th percentile) was 11.3% (n = 6) and 15.1% (n = 8), respectively, with no differences by ultrasound stage. The median birth weight centile was 64 (IQR, 26-85), with no differences between cases and controls or by ultrasound stage.

CONCLUSIONS

In our cohort, a diagnosis of PAS was not associated with fetal growth restriction.

Prenatal findings and associated survival rates in fetal ventriculomegaly: A prospective observational study

OBJECTIVES

Fetal ventriculomegaly is associated with varying degrees of genetic and structural abnormalities. The objective was to present the experience of fetal ventriculomegaly in a large European center in relation to: 1. grade of ventriculomegaly; 2. additional chromosomal/structural abnormalities; and 3. perinatal survival rates.

METHODS

This was a prospective observational study of patients referred with fetal ventriculomegaly from January 2011 to July 2020. Data were obtained from the hospital database and analyzed to determine the rate of isolated ventriculomegaly, associated structural abnormalities, chromosomal/genetic abnormalities, and survival rates. Data were stratified into three groups; mild (Vp = 10-12 mm), moderate (Vp = 13-15 mm) and severe (Vp > 15 mm) ventriculomegaly.

RESULTS

There were 213 fetuses included for analysis. Of these 42.7% had mild ventriculomegaly, 44.6% severe and 12.7% had moderate ventriculomegaly. Initial ultrasound assessment reported isolated ventriculomegaly in 45.5% fetuses, with additional structural abnormalities in 54.5%. The rate of chromosomal/genetic abnormalities was high,16.4%. After all investigations, the true rate of isolated VM was 36.1%. The overall survival was 85.6%. Survival was higher for those with isolated VM across all groups (P < 0.05).

CONCLUSION

Ventriculomegaly is a complex condition and patients should be counselled that even with apparently isolated VM, there remains the possibility of additional genetic and/or structural problems being diagnosed in up to 10% of fetuses.

Mid‐Arm Point in PAEDiatrics (MAPPAED): An effective procedural aid for safe pleural decompression in trauma

OBJECTIVE

Life-threatening thoracic trauma requires emergency pleural decompression and thoracostomy and chest drain insertion are core trauma procedures. Reliably determining a safe site for pleural decompression in children can be challenging. We assessed whether the Mid-Arm Point (MAP) technique, a procedural aid proposed for use with injured adults, would also identify a safe site for pleural decompression in children.

METHODS

Children (0-18 years) attending four EDs were prospectively recruited. The MAP technique was performed, and chest wall skin marked bilaterally at the level of the MAP; no pleural decompression was performed. Radio-opaque markers were placed over the MAP-determined skin marks and corresponding intercostal space (ICS) reported using chest X-ray.

RESULTS

A total of 392 children participated, and 712 markers sited using the MAP technique were analysed. Eighty-three percentage of markers were sited within the 'safe zone' for pleural decompression (4th to 6th ICSs). When sited outside the 'safe zone', MAP-determined markers were typically too caudal. However, if the site for pleural decompression was transposed one ICS cranially in children ≥4 years, the MAP technique performance improved significantly with 91% within the 'safe zone'.

CONCLUSIONS

The MAP technique reliably determines a safe site for pleural decompression in children, albeit with an age-based adjustment, the Mid-Arm Point in PAEDiatrics (MAPPAED) rule: 'in children aged ≥4 years, use the MAP and go up one ICS to hit the safe zone. In children <4 years, use the MAP.' When together with this rule, the MAP technique will identify a site within the 'safe zone' in 9 out of 10 children.

Relationship Between MRI Scoring Systems and Neurodevelopmental Outcome at Two Years in Infants With Neonatal Encephalopathy

BACKGROUND

Magnetic resonance imaging (MRI) scoring systems are used in the neonatal period to predict outcome in infants with neonatal encephalopathy. Our aim was to assess the relationship between three MRI scores and neurodevelopmental outcome assessed using Bayley Scales of Infant and Toddler Development, third edition (Bayley-III), at two years in infants with neonatal encephalopathy.

METHODS

Term-born neonates with evidence of perinatal asphyxia born between 2011 and 2015 were retrospectively reviewed. MRI scanning was performed within the first two weeks of life and scored using Barkovich, National Institute of Child Health and Human Development (NICHD) Neonatal Research Network (NRN), and Weeke systems by a single assessor blinded to the infants clinical course. Neurodevelopmental outcome was assessed using composite scores on the Bayley-III at two years. Multiple linear regression analyses were used to assess the association between MRI scores and Bayley-III composite scores, with postmenstrual age at scan and sex included as covariates.

RESULTS

Of the 135 recruited infants, 90 infants underwent MRI, and of these, 66 returned for follow-up. MRI abnormalities were detected with the highest frequency using the Weeke score (Barkovich 40%, NICHD NRN 50%, Weeke 77%). The inter-rater agreement was good for the Barkovich score and excellent for NICHD NRN and Weeke scores. There was a significant association between Barkovich, NICHD NRN, and Weeke scores and Bayley-III cognitive and motor scores. Only the Weeke score was associated with Bayley-III language scores.

CONCLUSIONS

Our findings confirm the predictive value of existing MRI scoring systems for cognitive and motor outcome and suggest that more detailed scoring systems have predictive value for language outcome.

Severe fetal ventriculomegaly: Fetal morbidity and mortality, caesarean delivery rates and obstetrical challenges in a large prospective cohort

INTRODUCTION

Severe fetal ventriculomegaly (VM) is defined as an enlargement of the atria of the lateral cerebral ventricles (Vp) of greater than 15 mm. While it is well established that it confers significant risk of morbidity and mortality to the neonate, there is limited information pertaining to the caesarean delivery rates and the obstetric management of these complex cases. The aim of this study was twofold: firstly, to determine survival rates in fetuses with severe VM, and secondly to determine the caesarean delivery rates in continuing pregnancies. We explore the obstetric challenges associated with these difficult cases.

METHODS

This was a prospective observational study of patients with antenatal severe VM, attending the Department of Fetal Medicine, National Maternity Hospital, Dublin, Ireland, from 1st January 2011 to 31st July 2020. Data were obtained from the hospital database and those with severe VM (Vp > 15 mm) were identified. The rates of chromosomal abnormalities, the survival rates and the caesarean delivery (CD) rates for the overall group were then determined. The data were then further sub-divided into two groups: 1. Vp < 20 mm and 2. Vp > 20 mm, and the results compared. Statistical analysis was performed using the Chi-Square test.

RESULTS

A total of N = 95 pregnancies with severe VM were included for analysis, of which additional structural abnormalities on ultrasound were apparent in 67/95 (70.5%) and 28/95 (29.5%) had isolated severe VM. Chromosomal abnormalities were diagnosed in 15/95 (15.8%) of cases, with (2/28) 7.1% in the isolated SVM group versus (13/67) 19.4% in the non-isolated SVM group. The overall survival rate (excluding TOP) was 53/74 (71.6%), with 20/23 (86.9%) in the isolated SVM group. The overall CD rate was 47/72 (65.3%), which was significantly higher than the CD for the hospital during the same time period of 25.4% (P < 0.01). The data were subdivided into Vp < 20 and Vp > 20 and those with a Vp > 20 had higher rates of additional intracranial findings on ultrasound (Vp < 20 13/41 (31.7%) versus Vp > 20 32/54 (59.3%) (P < 0.05)) and macrocrania (Vp < 20 14/41 (34.1%) versus Vp > 20 35/54 (64.8%) (P < 0.05)). No significant difference was observed in the overall survival or CD rates between the two groups.

CONCLUSION

In conclusion this study reports significant fetal morbidity and mortality with severe VM with high CD rates observed in this cohort. Significant challenges exist in relation to the obstetric management and counseling of parents regarding an often uncertain neonatal prognosis. In continuing pregnancies with significant macrocrania delivery plans should be individualized to improve neonatal outcomes where possible and minimize harm to the mother.

Comparing three-dimensional models of placenta accreta spectrum with surgical findings

OBJECTIVE

Placenta accreta spectrum (PAS) is associated with significant maternal morbidity mainly related to blood loss. Pre-operative planning is aided by antenatal ultrasound and magnetic resonance imaging. We sought to assess whether three-dimensional (3D) models from MR images were accurate when compared with surgical and pathological findings.

METHODS

Digital Imaging and Communications in Medicine files containing MR images with varying severity of PAS (n = 4) were modeled using 3D Slicer. Placenta, bladder, and myometrial defects were modeled. Myometrial defects at three different uterine locations were included-anterior, lateral and inferior. 3D models were used to identify the relationship between the myometrial defect and the internal cervical os. Findings were validated in a larger series of PAS cases (n = 14) where patterns of invasion were compared with estimated blood loss and distance from defect to the internal os.

RESULTS

The defect illustrated in the four 3D models correlates to both surgical and pathological findings in terms of depth and pattern of invasion, location of defect, bladder involvement. Blood loss and topography of the defect from 3D modeling were examined in 14 further cases. Inferior defects were associated with increased blood loss compared with anterior defects. Increased distance from cervix was associated with reduced blood loss (R²  = 0.352, P = 0.01).

CONCLUSION

Three-dimensional models of PAS provide an accurate preoperative description of placental invasion and should be investigated as a tool for selecting patients for uterine-conserving surgery. Accurate 3D models of placenta accreta spectrum are achievable and may provide additional information, such as distance of the defect from the internal os.

Maternal morbidity in placenta accreta spectrum following introduction of a multi-disciplinary service compared to standard care: an Irish perspective

AIM

The purpose of this study is to compare maternal outcomes in patients with placenta accreta spectrum (PAS) when managed as part of a multi-disciplinary team (MDT) compared to standard care.

METHODS

Patients in the standard care group were retrospectively identified from pathology records, with patients in the MDT group prospectively collected on an electronic database. Data on maternal demographics, delivery, estimated blood loss (EBL), transfusion requirements, and morbidity were recorded.

RESULTS

Sixty patients were diagnosed with PAS between 2006 and 2019, of whom 32 were part of the standard care group and 28 in the MDT group. Compared to standard care, MDT care was associated with an increase in antenatal diagnosis from 56.3 to 92.9% (p < 0.0001), a significant reduction in EBL (4150 mL (800-19500) vs 1975 (495-8500), p < 0.0001), and transfusion requirements (median 7 (0-30) units of RCC vs 1 (0-13), p < 0.0001).

CONCLUSION

PAS is associated with significant maternal morbidity and warrants management in an MDT setting with specialist input, which is associated with improved outcomes.

Diffusion tensor imaging in neonatal encephalopathy: a systematic review

BACKGROUND AND OBJECTIVE

Diffusion tensor imaging (DTI) during the first few days of life can be used to assess brain injury in neonates with neonatal encephalopathy (NE) for outcome prediction. The goal of this review was to identify specific white matter tracts of interest that can be quantified by DTI as being altered in neonates with this condition, and to investigate its potential prognostic ability.

METHODS

Searches of Medline and the Cochrane Database of Systematic Reviews were conducted to identify studies with diffusion data collected in term-born neonates with NE.

RESULTS

19 studies were included which described restricted diffusion in encephalopathic neonates as compared with healthy controls, with the posterior limb of the internal capsule and the genu and splenium of the corpus callosum identified as particular regions of interest. Restricted diffusion was related to adverse outcomes in the studies that conducted a follow-up of these infants.

CONCLUSIONS

Obtaining diffusion measures in these key white matter tracts early in life before pseudonormalisation can occur can not only identify the extent of the damage but also can be used to examine the effectiveness of treatment and to predict neurodevelopmental outcome.

Dysregulated Monocyte and Neutrophil Functional Phenotype in Infants With Neonatal Encephalopathy Requiring Therapeutic Hypothermia

Neonatal encephalopathy (NE) is a significant cause of morbidity and mortality. Persistent inflammation and activation of leukocytes mediate brain injury in NE. The standard of care for NE, therapeutic hypothermia (TH), does not improve outcomes in nearly half of moderate to severe cases, resulting in the need for new adjuvant therapies, and immunomodulation holds promise. Our objective was to explore systemic leukocyte phenotype in infants with NE and healthy controls in response to lipopolysaccharide (LPS). Twenty-four infants with NE (NE II-20; NE III = 4) requiring TH and 17 term neonatal controls were enrolled, and blood samples were analyzed between days 1 and 4 of life at a mean (SD) timepoint of 2.1 (± 0.81) days of postnatal life at the time of the routine phlebotomy. Leukocyte cell surface expression levels of Toll-like receptor 4, NADPH oxidase (NOX2), CD11b, mitochondrial mass, and mitochondrial superoxide production were measured by flow cytometry. Gene expression of TRIF (TIR domain-containing adapter-inducing interferon-β), MyD88 and IRAK4 was measured by reverse transcription-polymerase chain reaction. Infants with NE had significantly lower expression of neutrophil CD11b and NOX2 with LPS stimulation compared to healthy term controls. Mitochondrial mass in neutrophils and monocytes was significantly increased in NE infants with LPS compared to controls, potentially indicating a dysregulated metabolism. Infants with NE had significantly lower IRAK4 at baseline than controls. NE infants display a dysregulated inflammatory response compared to healthy infants, with LPS hyporesponsiveness to CD11b and NOX2 and decreased IRAK4 gene expression. This dysregulated immune profile may indicate an adaptable response to limit hyperinflammation.

Imaging of soft tissue and osseous sarcomas of the extremities

Soft tissue and osseous sarcomas of the extremities are uncommon malignancies that represent very important diagnostic entities because of their aggressive nature. Radiologic investigations, including plain film, computed tomography, contrast-enhanced magnetic resonance imaging; scintigraphy, ultrasound, and positron emission tomography-computed tomography, play critical roles in providing a differential, establishing the diagnosis, demonstrating prognostic characteristics, and tailoring tumor treatment. The purpose of this review is to describe the most common soft tissue and osseous sarcomas of the extremities, with emphasis on their plain film and magnetic resonance imaging characteristics with the aim of aiding the reader to accurately describe the important imaging features and generate an appropriate differential diagnosis to aid the referring clinician with prompt appropriate management and treatment.

Factors influencing delivery mode for nulliparous women with a singleton pregnancy and cephalic presentation during a 17-year period

OBJECTIVE

To evaluate the effects of maternal age, induction of labour, epidural analgesia and birth weight on mode of delivery in nulliparous women with a singleton pregnancy and cephalic presentation at > or =36 weeks gestation, and to describe how these factors and their influence have changed over a 17-year period from 1989 to 2005.

STUDY DESIGN

The study was conducted in the obstetric department of a university teaching hospital in Ireland. Of 45,647 women delivered, 14,867 were nulliparous with a singleton pregnancy and cephalic presentation and undergoing labour at > or =36 weeks gestation, and were included in the study. The main outcome measures were the influence of maternal age, induction of labour, epidural analgesia and birth weight on the mode of delivery. Multinomial logistic regression analysis for type of delivery and the associated explanatory variables and trend analysis of these variables were performed.

RESULTS

There was a significant progressive increase in both unplanned abdominal delivery and instrumental vaginal delivery, with advancing maternal age. Induction of labour increased the risk of unplanned abdominal delivery (OR 1.92; 95% CI 1.73-2.14). Epidural analgesia was associated with an increased risk of instrumental vaginal delivery (OR 4.68; 95% CI 4.18-5.25), and unplanned abdominal delivery (OR 2.29; 95% CI 1.98-2.66). Mothers of infants with birth weight > or =4.5 kg were less likely to be delivered by instrumental vaginal delivery (OR 0.60; 95% CI 0.41-0.88), than mothers delivering infants in the 2.50-4.49 kg birth weight category. Between 1989 and 2005 there was a significant increase in maternal age (P=0.0001), birth weight (P=0.042) and unplanned abdominal delivery rates (P=0.0004), and a reduction in instrumental vaginal delivery rates (P=0.0013).

CONCLUSIONS

These data demonstrate that the increasing trend of unplanned abdominal delivery in nulliparous women with a singleton pregnancy and cephalic presentation may be partially explained by advancing maternal age, and other obstetric factors also play a significant role.

The TGFBR1*6A/9A polymorphism is not associated with differential risk of breast cancer

A polymorphic 9-bp deletion in exon 1 of TGFBR1 (TGFBR1*6A) has been identified as a low-penetrance cancer susceptibility allele. The strongest association in the initial studies was with breast cancer; however, these studies included patients with different types of cancer, including colon, cervical and breast carcinomas, with only a small proportion being breast cancer patients. In subsequent case-control studies focussing on breast cancer alone, the results have been equivocal. In order to clarify whether TGFBR1*6A is associated with breast cancer risk, we have genotyped this polymorphism in 988 breast cancer cases and 1,016 controls from the West of Ireland and also performed a meta-analysis of previously published data (5,150 cases and 6,344 controls). In our series from the West of Ireland, we found no association (genotypic odds ratio (OR) under a dominant model = 0.93, 95% confidence interval (CI) 0.73-1.19, P = 0.57; allelic OR = 0.93, 95% CI 0.74-1.15, P = 0.49). Meta-analysis showed evidence of heterogeneity among studies. Using the random effects model, it was found that there was no evidence of an association of the *6A allele with breast cancer (genotypic OR under a dominant model = 1.10, 95% CI = 0.94-1.28, P = 0.24, allelic OR = 1.12, 95% CI 0.97-1.31, P = 0.13). In conclusion, our study shows that there is no association between TGFBR1*6A and breast cancer risk.

Evaluation of variants in BRIP1, PALB2 and CHEK2 in a west of Ireland breast cancer cohort

Abstract #3092

Introduction&#x2028; Positive family history is the most important risk factor in breast cancer predisposition. Recent studies have identified variants in BRIP1, PALB2 and CHEK2, which have been proposed as breast cancer susceptibility genes conferring an increased relative risk of 2-4%.&#x2028; Aims&#x2028; To evaluate the role of the above variants in the West of Ireland population and to examine their potential clinical relevance.&#x2028; Methods&#x2028; Proposed candidate genetics variants in BRIP1, PALB2 and CHEK2 were interrogated in 192 patients with a high risk of familial breast cancer. Genescan analysis and direct sequencing were used to evaluate these variants. Where a variant was exhibited, it was then examined further in 990 sporadic breast cancer patients and 1016 matched non-cancer controls using KASPar genotyping technology.&#x2028; Results&#x2028; We demonstated mutations in BRIP1 and CHEK2 genes. 1 mutation was found in BRIP1 2392C→T in our 192 patients with a high risk of familial breast cancer. 5 breast cancer patients and 1 control exhibited a CHEK2110delC mutation within 990 breast cancer patients and 1016 matched non-cancer controls. Mutations previously demonstrated in PALB2 were not evident in 192 high risk patients.&#x2028; Conclusions&#x2028; We have confirmed the presence of variants in BRIP1 and CHEK2, candidate moderate penetrance genes, in breast cancer patients with a strong family history of breast cancer. This may have implications in clinical practice as our knowledge of these variants expands. The absense of PALB2 variants in patients at high genetic risk points to a low clinical significance. Our findings contribute to a better understanding of inherited breast cancer risk while helping to optimize future screening, therapeutic and prophylactic programs.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3092.

Concurrent diagnosis of Crohn's disease and colorectal carcinoma in a young man with abdominal pain

The lead time between diagnosis of Crohn's disease and presentation with a Crohn's related malignancy is generally twenty years from diagnosis. This case outlines that of a young man who presented to the emergency department with abdominal pain and was subsequently discovered to have a malignant stricture complicating underlying Crohn's disease that was previously quiescent and undiagnosed. It demonstrates that a new diagnosis of Crohn's disease does not rule out previously quiescent underlying disease and therefore risk of colrectal carcinoma.

A comparison of surgical impression, histological findings and microbiological results at open appendicectomy

There is no accurate predictor of complications following open appendicectomy. Surgical impression, histological findings and peritoneal culture swabs have been used. The value of peritoneal culture swab was assessed in this study. All patients undergoing open appendicectomy between January 2003 and December 2005 were included in the study. During the 24-month period, 952 patients underwent open appendicectomy. Peritoneal culture swabs were taken from 309 patients (32%). There was a significant difference in the mean postoperative length of stay +/- SEM between those with a positive culture (7 days +/- 0.6), those with a sterile culture result (3.7 days +/- 0.2) and those on whom a culture swab was not taken (4.9 days +/- 0.3); p<0.0001, ANOVA. Surgeons were more likely to overcall the severity of the appendix pathology (p < 0.0001 surgical vs. histological findings; Fisher's exact test), however, there was no significant difference in the power of surgical or histological assessment of the appendicitis at predicting a positive peritoneal culture result. Complex appendicitis was more likely to be associated with a positive peritoneal culture (P < 0.0001; Fisher's exact test). No antibiotic regime was changed on the basis of a positive culture swab. Fifteen patients were readmitted within 6 months of appendicectomy, predictors of readmission included histologically confirmed complex appendicitis and a positive peritoneal culture swab. Peritoneal culture swabs do not improve immediate postoperative therapy based on surgical impression and rapid histological reporting, however, the routine use of peritoneal culture swabs may be of value in identifying patients requiring outpatient follow-up.

The 16s/23s ribosomal spacer region as a target for DNA probes to identify eubacteria

Variable regions of the 16s ribosomal RNA have been frequently used as the target for DNA probes to identify microorganisms. In some situations, however, there is very little sequence variation observed between the 16s rRNA genes of closely related microorganisms. This study presents a general method to obtain species-specific probes using the spacer (intergenic) region between the 16s and 23s rRNA genes. The overall strategy is analogous to that which has previously been developed for the variable regions of the 16s rRNA genes. Sequence analysis of the 16s rRNA and 23s rRNA coding sequences flanking the spacer regions resulted in the design of PCR primers that can be used to amplify the spacer regions of a wide range of eubacteria. Sequencing the amplified spacer region then gives rise to the information that can be used to select specific DNA sequences for use as a DNA probe or for the generation of specific PCR primers to a microorganism of interest. In this study the approach to develop specific DNA markers for members of the genus Clostridium is described in detail. A specific DNA oligonucleotide probe and PCR primers have been designed for Clostridium perfringens that distinguish it from other organisms in the genus.