Single best answer question-writing tips for clinicians.

Assessment is essential for progression in medical careers. Thus, an important aspect of developing as a clinical teacher is the ability to produce high-quality assessments for junior colleagues. The single best answer (SBA) question format is becoming ubiquitous in the assessment of the application of knowledge in clinical medicine; writing this style of examination question can be a challenge. This concise guide highlights key SBA question-writing tips, aiming to help aspiring clinical teachers set high-quality knowledge assessments.

Gene Expression Signatures as Biomarkers of Tumour Hypoxia.

Hypoxia is a feature of most solid tumours and is associated with a poor prognosis. The hypoxic environment can reduce the efficacy of radiotherapy and some chemotherapeutics, and has been investigated extensively as a therapeutic target. The clinical use of hypoxia-targeting treatment will benefit from the development of a biomarker to assess tumour hypoxia. There are several possible techniques that measure either the level of oxygen or the tumour molecular response to hypoxia. The latter includes gene expression profiling, which measures the transcriptional response of a tumour to its hypoxic microenvironment. A systematic review identified 32 published hypoxia gene expression signatures. The methods used for their derivation varied, but are broadly classified as: (i) identifying genes with significantly higher or lower expression in cancer cells cultured under hypoxic versus normoxic conditions; (ii) using either previously characterised hypoxia-regulated genes/biomarkers to define hypoxic tumours and then identifying other genes that are over- or under-expressed in the hypoxic tumours. Both generated gene signatures useful in furthering our understanding of hypoxia biology. However, signatures derived using the second method seem to be superior in terms of providing prognostic information. Here we summarise all 32 published hypoxia signatures, discuss their commonalities and differences, and highlight their strengths and limitations. This review also highlights the importance of reproducibility and gene annotation, which must be accounted for to transfer signatures robustly for clinical application as biomarkers.

Operative management of abdominal injuries in children.

Operative repair of visceral injuries in children is infrequent enough so that an individual surgeon's experience may decay as time goes by. This report recommends incisions, a plan for thorough exploration, and the best surgical strategies for abdominal injuries, Simplicity and organ conservation are emphasized.

Teamwork in pediatric trauma centers.

Various models have been proposed for optimal care of children in the trauma centers of general hospitals. The authors discuss the determinants of successful pediatric trauma care. In-house trauma surgeons, a consensus protocol for the first 20 minutes of resuscitation, real-time involvement of radiologists as part of the trauma team, and professional respect are the basis of teamwork.

Effects of mechanical and thermal fatigue on dental drill performance.

Osseous integration of dental implants depends on the use of proper surgical technique during site preparation, including the prevention of thermal injury to the surrounding bone. Heat generation during drilling has been reported to positively correlate with the production of forces at the surgical site. In this study, peak torque and axial load levels were measured during a drilling procedure into a polymeric material simulating the human mandible. Axial rotary milling was performed using 5 different twist drill designs (3i Irrigated Tri-Spade, 3i Disposable, Nobel-Biocare, Straumann, and Lifecore) of 15 to 20 mm in length and 2 to 2.3 mm in diameter, at a free-running rotational speed of 1,500 rpm and continuous feed rate of 3.5 mm/second, to a total depth of 10.5 mm. Ten drills representing each of the 5 types (n = 50) were subjected to 30 individual drill "pecks" and heat-sterilized every 3 "pecks" to determine the effects of cyclic mechanical and thermal loading on drill performance. Normal stress (sigma) and shear stress (tau) were calculated from the kinetic data and drill geometries. A drill efficiency coefficient (mu) was also calculated as the ratio of torsional resistance to translational resistance. Overall, the hypotheses of drill performance dependency on drill type as well as mechanical and thermal accumulated loading were tested and confirmed (P < .05). The 5 drill types produced a range of normal stresses (2.54 to 5.00 MPa), shear stresses (9.69 to 29.71 MPa), and efficiency (1.16 to 3.16) during repeated testing. Scanning electron microscopic images revealed minor deformations in the cutting edges of the tri-spade drills following testing.

Carotid artery thrombosis and stroke after blunt pharyngeal injury.

A 2-year-old child fell on a toothbrush, sustaining a pharyngeal injury. Eighteen hours later, localizing symptoms of a cerebrovascular accident became evident. Magnetic resonance angiography showed occlusion of the internal carotid artery and a cerebral infarction. She was treated with anticoagulation and made a complete recovery. Pharyngeal injuries may be complicated by internal carotid artery thrombosis and embolus. Management includes prompt diagnosis, anticoagulation, and carotid artery exploration in selected cases.

Color Doppler aided prenatal diagnosis of a type 1 cystic sacrococcygeal teratoma simulating a meningomyelocele.

Type 1 cystic sacrococcygeal teratomas, usually associated with good outcome following neonatal resection, must be differentiated at the time of prenatal diagnosis from sonographically similar meningomyeloceles, which carry a grave prognosis. We present an unusual case in which color Doppler imaging assisted correct midtrimester prenatal diagnosis of a large type 1 cystic sacrococcygeal teratoma closely simulating a meningomyelocele.

Renal cell carcinoma in association with tuberous sclerosis in children.

Tuberous sclerosis, a genetically transmitted multisystem neurocutaneous disorder, is associated with renal lesions in 50% of cases. The expected lesions are angiomyolipomas or renal cysts; renal cell carcinoma has been encountered in adults who have tuberous sclerosis, but is very rare in children. The authors report the case of a 5-year-old girl with tuberous sclerosis for whom atypical computed tomography findings led to the diagnosis of renal carcinoma at an early age. This experience suggests that children with tuberous sclerosis may need earlier screening.

Recurrence of immune thrombocytopenic purpura after splenectomy.

Immune thrombocytopenic purpura (ITP) frequently leads to splenectomy. Accessory spleens maybe found in a variety of locations, and may not be readily apparent. Retained accessory splenic tissue can lead to recurrent ITP, which, this report (involving multiple relapses in a single patient) demonstrates.

Prenatal diagnosis and the pediatric surgeon: the impact of prenatal consultation on perinatal management.

PURPOSE: Pediatric surgeons are increasingly called on by obstetrical colleagues to counsel parents about the implications of a prenatal ultrasound finding. Our understanding of the natural history of many prenatally diagnosed surgical conditions has grown significantly in recent years. Whether prenatal surgical consultation can influence perinatal course had not been investigated. METHODS: During an 21-month period, 12,865 prenatal ultrasound studies were performed on a total of 4,551 patients, and 221 prenatal surgical consultations were obtained through a newly established fetal treatment program at a tertiary care prenatal diagnostic center. To evaluate the impact of prenatal pediatric surgical consultation on perinatal course, the authors reviewed changes in management including termination of pregnancy, in utero intervention, and altered site, mode, or timing of delivery. RESULTS: Two hundred twenty-one fetuses were referred for consultation; their 234 congenital anomalies included genitourinary (36%), thoracic (16%), intraabdominal (14.5%), abdominal wall (10.6%), neurological (9%), skeletal (6%), and head and neck (2.5%) defects; 2.5% had tumors and 2.5% were twin pregnancies. Pregnancy was terminated in 9.5% of cases, because of patient request, chromosomal abnormality, or dismal prognosis. In 3.6%, the decision to terminate was changed as a result of consultation. Site of delivery was changed as a result of consultation in 37% to facilitate postnatal evaluation and initiate immediate treatment. Mode of delivery was changed in 6.8% to prevent dystocia, hemorrhage into a tumor, as in sacrococcygeal teratoma, or to provide an emergency airway, as in cervical teratoma. The timing of delivery was changed in 4.5% to avoid further damage to fetal organs in cases of obstructive uropathy, gastroschisis, sacrococcygeal teratoma with high-output failure, and hydrocephalus. Five percent (11) underwent treatment in utero for fetal hydrothorax, obstructive uropathy, twin-twin transfusion syndrome, or lymphangioma. The overall perinatal mortality rate was 2.5%. CONCLUSION: Prenatal pediatric surgical consultation may have a significant impact on the perinatal management of the fetus with a surgically correctable congenital anomaly. Providing obstetric colleagues and families with valuable insight into the surgical management of anomalies allows fetal intervention when appropriate, and delivery in an appropriate setting, by the safest mode of delivery, and at the gestational age appropriate to minimize effects of the anomaly.

Transanastomotic feeding tubes in repair of esophageal atresia.

To avoid the need for a gastrostomy and parenteral nutrition during the 7- to 10-day healing period after esophageal anastomosis, the authors modified their technique for esophageal atresia repair to include placement of a transanastomotic feeding tube. A SILASTIC transanastomotic feeding tube and early enteral nutrition was used for 19 of 23 consecutively treated patients after repair of esophageal atresia and tracheoesophageal fistula. One of the 19 patients had recurrent fistula and another had an anastomotic leak. Five patients had significant gastroesophageal reflux (noted on barium esophagram), and four had strictures that required dilatation. Parenteral nutrition was necessary for only two patients. The authors conclude that transanastomotic feeding tubes and early enteral nutrition are safe and effective, reduce costs, and do not appear to increase the incidence of anastomotic leaks, strictures, or gastroesophageal reflux.

Hospital reimbursement for pediatric trauma care.

PURPOSE: Despite the proven efficacy of pediatric trauma centers, their continued development is threatened by the perception that their cost exceeds the reimbursement for their services. The authors reviewed actual reimbursement for a group of pediatric trauma patients and compared with that for a group of appendectomy patients chosen to reflect the authors' surgical population at large. METHODS: The records of 209 consecutively treated trauma patients and 37 age-matched appendectomy patients treated in 1992 and 1993 were reviewed. Trauma patients were divided into two groups: moderate injury (ISS < or = 9; n = 134) and serious injury (ISS > or = 10; n = 75). RESULTS: Hospital bills for the appendectomy patients were reimbursed at 72% of charges and 112% of costs. Payment was received at a mean of 36 days (range, 9 to 62 days) after discharge. Reimbursement for moderately injured patients was 104% of charges and 137% of costs and was received at a mean of 81 days (range, 3 to 270 days) after discharge. Six months postdischarge, reimbursement for seriously injured patients was 63% of charges and 86% of costs. Reimbursement was slow for some children who sustained severe injury, but as legal actions brought by patient's families were completed, open accounts were settled, and revenue in both groups totaled 76% of charges and 103% of costs 18 months postdischarge. CONCLUSION: Hospital reimbursement for care at a level I pediatric trauma center exceeds 75% of charges and 100% of costs, no different from the overall rate for the general hospital surgical population. Analysis of reimbursement rates for trauma patients may be time-dependent.

The natural history of meconium peritonitis diagnosed in utero.

The authors reviewed their experience with meconium peritonitis (MP) diagnosed in utero to define criteria for prenatal and postnatal management. Prenatal diagnosis was made by identifying abdominal calcification on serial ultrasound examinations in nine fetuses, between 18 and 37 weeks' gestation. Cases without associated bowel abnormalities were considered "simple MP" and those with bowel abnormalities were considered "complex MP." Five cases of simple MP were identified at 18, 23, 30, 34, and 37 weeks' gestation. These five fetuses were delivered at term and had normal abdominal examinations. Abdominal radiographs were obtained in three showing normal bowel gas patterns, and abdominal calcifications in only two. All five patients were fed uneventfully. Four cases of complex MP were identified at 26, 26, 31, and 31 weeks' gestation. All four fetuses had dilated loops of bowel. Two of the four had meconium cysts, one of which was associated with ascites and the other with polyhydramnios. Shortly after birth both infants with meconium cysts required ileal resection and ileostomy for ileal atresia and ileal perforation, respectively. The remaining two infants had no evidence of dilated bowel, meconium cyst, or ascites on postnatal radiograph and were fed uneventfully. These data suggest that only 22% of fetuses with a prenatal diagnosis of MP develop complications that require postnatal operation. Gestational age at diagnosis does not correlate with postnatal outcome. Fetuses with complex MP are at increased risk for postnatal bowel obstruction and perforation.

The immune response to trauma.

The response to trauma begins in the immune system at the moment of injury. The loci are the wound, with activation of macrophages and production of proinflammatory mediators, and the microcirculation with activation of endothelial cells, blood elements, and a capillary leak. These processes are potentiated by ischemia and impaired oxygen delivery and by the presence of necrotic tissue, each exacerbating the inflammatory response. Hemorrhage alone may be a sufficient stimulus. Inflammation once was considered to be a host reaction to bacteria or other irritants. This concept was expanded by the discovery of autoimmune diseases, and we are now aware that some illnesses are the result of the body's response to an invader rather than the direct effect of the invader itself. The discoveries about the response to trauma described here add another dimension, showing inflammation to be a fundamental life process that begins at the molecular level at the moment of injury and that, depending on the severity of the stimulus and the effectiveness of initial treatment, may spread to include every cell, tissue, and organ in the body, for good or ill. An important part of these expanding concepts is the notion that all noxious stimuli activate the cytokine system as a final common pathway. Sepsis, hemorrhage, ischemia, ischemia-reperfusion, and soft tissue trauma all share an ability to activate macrophages and produce proinflammatory cytokines that may initiate the SIRS. Second-message compounds and effector molecules mediate the observed clinical phenomena.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet activating factor-antagonist improves survival in experimental staphylococcal septicemia.

Platelet activating factor (PAF) amplifies the cytokine cascade in experimental models. This study was designed to investigate the role of PAF blockade during experimental Gram-positive shock by pretreatment with platelet activating factor-antagonist (PAF-A). Three groups of anesthetized rabbits were studied. Control animals received either saline or PAF-A only, and all survived, without hemodynamic changes. Animals in the second group received an infusion of Staphylococcus epidermidis, and all died in septic shock. Animals in the third group were pretreated with PAF-A and given the staphylococcal infusion; five of the six were alive at 200 minutes, with near-normal hemodynamics. The survival rate for animals pretreated with PAF-A was significantly higher than that for animals receiving staphylococci alone (P < .02). These results suggest that PAF is an important mediator of Gram-positive sepsis. Antagonism of PAF may be an effective potential therapy for sepsis.

Prenatal diagnosis and management of gastrointestinal anomalies.

The increased use of prenatal sonography has led to earlier and more frequent diagnosis of a wide range of gastrointestinal anomalies. Many of these anomalies are associated with other severe cardiac, renal, and genetic abnormalities that may impact on decisions regarding timing and site of delivery. The majority of these patients should be referred to a center that provides perinatal, neonatal, and pediatric surgical expertise. After a complete prenatal evaluation, a decision regarding the site of delivery and the need for subspecialty referral can be made. Prenatal diagnosis of the conditions discussed in this article does not influence the mode of delivery, but subsequent management of the newborn is improved by delivery in a tertiary care center.

Diagnosis and management of fetal neuroblastoma.

At 36 weeks' gestation, in a 30-year-old patient, routine prenatal ultrasound examination revealed a cystic mass in the left adrenal gland. The pregnancy was uneventful, and at delivery the infant had a palpable left flank mass confirmed by ultrasound and computed tomography scan. There were no metastases. On the second day of life, a 5 cm cystic stage-I neuroblastoma was removed by adrenalectomy. The infant had an uneventful recovery, required no further treatment, and remains free of disease 26 months later.