Original Article

LGL Tan, YY Tan, D Heng, MY Chan
Correspondence: Dr Patrick M Y Chan, Patrick_Chan@ttsh.com.sg

ABSTRACT
Introduction The presence of axillary lymph node metastases is an important prognostic factor in breast cancer. Sentinel lymph node biopsy (SLNB) is an emerging method for the staging of the axilla. It is hoped that with SLNB, the morbidity from axillary lymph node dissection (ALND) can be avoided without compromising the staging and management of early breast cancer. However, only patients found to be SLNB negative benefit from this procedure, as those with positive SLNB may still require ALND. Our objective is to study the various clinico-pathological factors to find predictive factors for axillary lymph node involvement in early breast cancer. It is hoped that with these factors, we will be better able to identify groups of patients most likely to benefit from SLNB.
Methods A retrospective study of 380 early breast cancer cases (stage T1 and T2, N0, N1, M0) in women treated in the Department of General Surgery, Tan Tock Seng Hospital, between January 1999 and August 2002, was conducted. Incidence of nodal metastases was correlated with clinico-pathological factors, and analysed by univariate and multivariate analyses.
Results Approximately 35 percent of the 380 cases of early breast cancer had nodal metastases. Multivariate analyses revealed four independent predictors of node positivity: tumour size (p-value equals 0.0001), presence of lymphovascular invasion (p-value is less than 0.0001), tumours with histology other than invasive ductal or lobular carcinoma (p-value equals 0.04), and presence of progesterone receptors (p-value equals 0.05).
Conclusion We have found independent preoperative predictive factors in our local population for the presence of nodal metastases. This information can aid patient selection for SLNB and improve patient counselling.

Keywords: axillary lymph node, breast cancer, node dissection, sentinel lymph node biopsy
Singapore Med J 2005; 46(12): 693-697

S Namwongprom, S Boonyaprapa, M Ekmahachai, N Vilasdechanon, A Somwangprasert, S Sumitsawan, P Taya
Correspondence: Dr Sirianong Namwangprom, snamwong@mail.med.cmu.ac.th; sirinam@chiangmai.ac.th

ABSTRACT
Introduction To analyse and determine the clinical value of lymphoscintigraphy for sentinel lymph node (SLN) localisation in woman undergoing surgery for breast cancer, and evaluate the predictive value of SLN versus axillary lymph node (ALN) status in these patients.
Methods Preoperative breast lymphoscintigraphy was performed in 35 female patients with breast cancer and clinically-negative ALNs. The mean age was 52.8 years (age range 38 to 73 years). The lymphoscintigraphy was performed using 74 MBq of Tc-99m nanocolloid subdermal injection over the tumour. The SLN location was marked on the skin. All patients underwent standard modified radical mastectomy with axillary lymph node dissection (ALND). A comparison of SLN and ALN histopathological results was completed in order to define the means by which the SLN biopsy was able to reflect the final status of ALNs.
Results In 20/35 (57.1 percent) cases, SLNs were visualised in 20-minute dynamic imaging. In 12 patients, SLNs were seen after delayed imaging and/or by repositioning the patient. Overall, the estimated SLN identification rate was 91.4 percent. Of 32 patients in whom SLNs were localised by lymphoscintigraphy, nine were positive for metastatic tumours and the rest were negative for tumour involvement. In four of these nine patients, SLN was the only node that contained metastatic tumour cells while in five patients, an additional concomitant ALN metastasis was detected. In four patients, SLN was negative on frozen section, but skip ALN metastases were noted. Of three patients in which SLNs were not localised by lymphoscintigraphy, two had positive ALNs for tumour cells and the remaining one was negative for tumour involvement.
Conclusion We concluded that SLN localisation using lymphoscintigraphy is an accurate minimally-invasive procedure for staging breast cancer patients with clinically-negative ALNs, and can substantially reduce the morbidity and costs of surgical treatment by avoiding unnecessary ALND in the majority of patients.

Keywords: axillary lymph node, breast cancer, lymphoscintigraphy, preoperative breast lymphoscintigraphy, sentinel lymph node localisation
Singapore Med J 2005; 46(12): 688-692

KB Chua, IL Chua, IE Chua, KH Chua
Correspondence: Dr Chua Kaw Bing, chuakawbing@yahoo.com.sg

ABSTRACT
Introduction Dengue and dengue haemorrhagic fever are common and serious arboviral diseases endemic in a number of countries situated in both the tropical and subtropical belts.
Methods A prospective study was carried out to examine the environmental factors influencing the ovipositing behaviour of gravid female Aedes mosquitoes in a typical urbanised residential environment in Malaysia. This study reports the effect of the usual ultra-low volume fogging of insecticides carried out by public health officers on the collection of immature Aedes mosquitoes using ovitraps.
Results Throughout the study, no dead immature Aedes mosquitoes was noted in any of the ovitraps set up in all of the fogging and immediate post-fogging periods. The mean number of days of ovitrapping for immediate pre-fogging, fogging and post-fogging periods were 10.3, 10.1 and 10.4 days, respectively. There was no statistically significant difference in the mean duration of ovitrapping cycle among the immediate pre-fogging, fogging and immediate post-fogging periods. The total number of immature Aedes mosquitoes collected in the immediate post-fogging periods was more than the immediate pre-fogging periods, and both were more than the fogging periods. However, there was no statistically significant difference in the total number of immature Aedes mosquitoes collected at various periods. It was not unusual to find dead insects, spiders and even small animals collected in ovitraps or environment in the fogged locality within 48 hours of chemical fogging.
Conclusion In this study, the usual chemical fogging in natural environment was ineffective in breaking the reproductive lifecycle by eliminating gravid female Aedes mosquitoes.

Keywords: Aedes mosquitoes, chemical fogging, dengue fever, mosquitoes, ovitraps
Singapore Med J 2005; 46(11): 639-644

MA Khan, SF Mekan, Z Abbas, RA Smego, Jr
Correspondence: Dr M A Khan, mohammad.aslam@aku.edu

ABSTRACT
Introduction The precise incidence of concurrent malaria and enteric fever in most geographical areas is largely unknown, and no data on such an association exists in Asia. Because both malaria and enteric fever are hyperendemic in Pakistan, we sought to determine the frequency, epidemiology, and clinical and laboratory features of dual malaria and enteric fever in a tertiary care setting.
Methods We conducted a retrospective case-control study of 1,891 patients hospitalised with malaria over a ten-year period and identified 21 patients with concurrent culture-proven enteric fever.
Results Cases with dual infection had significantly more gastrointestinal symptoms at the time of admission, including nausea, vomiting, abdominal pain, and/or diarrhoea compared to matched control subjects with uncomplicated malaria (p-value is less than 0.006). Cases were more likely to have a continuous rather than intermittent fever (p-value is less than 0.0001), delayed defervescence in response to antimalarial treatment (p-value is less than 0.006), normal or low white blood cell counts (p-value is less than 0.04), relatively higher platelet counts among cases versus control (p-value is less than 0.05) and serum haemoglobin (p-value is less than 0.06), elevated alanine aminotransferase levels (p-value is less than 0.02), and a prolonged hospital stay (p-value is less than 0.03). The negative predictive values for gastrointestinal symptoms, continuous fever pattern and delayed defervescence were 80 percent, 72 percent and 74 percent, respectively.
Conclusion Patients with malaria who have marked gastrointestinal symptoms, continuous pattern of fever and persistence of fever for more than 24 hours after appropriate antimalarial therapy, should be investigated or empirically treated for concurrent enteric fever. The absence of the above clinical features in patients with uncomplicated malaria should reassure physicians that there is no concurrent typhoid fever.

Keywords: enteric fever, malaria, tropical infection, typhoid
Singapore Med J 2005; 46(11): 635-638

IH Garba, GA Ubom
Correspondence: Dr Ibrahim H Garba, ihgarba2002@yahoo.com

ABSTRACT
Introduction Lactate dehydrogenase (LDH) activity was assayed in the sera of 76 adult male and 76 adult female patients within the age group of 18-40 years presenting with acute, uncomplicated Plasmodium falciparum malaria infection and a control group of 80 healthy adults within the same age group.
Methods Patient selection and pre-qualification were done by simple random sampling of individuals presenting at the Bauchi Specialist Hospital Outpatient Department with a history of fever and malaise within a period of one to eight days, and who were confirmed to be infected with the P. falciparum malaria parasite by microscopical examination of Giemsa-stained thin blood slides.
Results The mean serum LDH activity in male patients was found to be 789.4 +/- 35.0 IU. This activity is significantly higher than the control LDH activity of 247.10 +/- 19.0 IU (p-value is less than 0.05). The mean serum LDH activity among female patients was 634.0 +/- 35.0 IU, which is a relatively higher activity compared to the control LDH activity of 247.10 +/- 19.0 IU (p-value is less than 0.05).
Conclusion The combination of acute hepatocellular injury and red cell haemolysis induced by the invading merozoites may account for the increase in serum LDH activity during this infection. Therefore serum LDH activity is a potentially valuable enzymatic marker of acute, uncomplicated P. falciparum malaria infection, especially in the absence of other complicating diseases known to be associated with the above normal serum LDH activities.

Keywords: lactate dehydrogenase, malaria, Plasmodium falciparum, serum enzymatic marker
Singapore Med J 2005; 46(11): 632-634

K Mamun, J Lim
Correspondence: Dr Kaysar Mamun, gdmkm@sgh.com.sg

ABSTRACT
Introduction Every year, a large number of patients with dysphagia are placed on feeding tubes to prevent aspiration pneumonia. This prospective study was planned to compare the incidence of aspiration pneumonia and death in patients with dysphagia who were either fed orally or through a nasogastric tube.
Methods All patients aged 65 years or older, at the point of discharge from the geriatric medicine ward of a hospital, were recruited over a six-month period with a two-month follow-up. Patients diagnosed with dysphagia by the speech therapist were recommended to have either oral feeding with modified diet or nasogastric tube feeding. The incidence of aspiration pneumonia and death among patients on oral feeding, nasogastric tube feeding and patients who refused nasogastric tube feeding were compared.
Results A total of 122 patients completed the study. The rate of aspiration pneumonia and death were, respectively, 31.2 percent in nasogastric tube-fed patients and 10.3 percent in orally-fed patients (Fisher's exact test, p-value equals 0.007). Multivariate analysis showed that the mode of feeding predicted outcome (p-value equals 0.03). The rate of aspiration pneumonia and death were 31.2 percent in nasogastric tube-fed patients and 11.5 percent in those who refused nasogastric tube feeding (Fisher's exact test, p-value equals 0.064). Nasogastric tube-fed patients were more cognitively- and functionally-impaired compared to those on oral feeding.
Conclusion In our study, patients on nasogastric tube feeding did not have a better outcome against aspiration pneumonia and mortality when compared to those who were on oral feeding. The poorer outcome of nasogastric tube-fed patients could be attributed to their worse cognitive and functional statuses. Larger studies are needed to refute or confirm the usefulness of nasogastric tube in elderly patients with dysphagia.

Keywords: aspiration pneumonia, elderly patients, enteral nutrition, nasogastric tube feeding, pneumonia
Singapore Med J 2005; 46(11): 627-631

VH Chong, HB Yim, CC Lim
Correspondence: Dr Chong Vui Heng, chongvuih@yahoo.co.uk

ABSTRACT
Introduction As the population ages, the incidence of biliary tract pathologies also increases, leading to an increase in the demand for endoscopic retrograde cholangiopancreatography (ERCP) interventions. Our aims are to assess the outcomes, safety and complications associated with ERCP performed in an elderly population.
Methods Patients aged 80 years or over referred for ERCP from January 1999 to September 2002, were identified and retrospectively reviewed.
Results 103 patients (68 females, mean age 84.6 +/- 3.9 years old) underwent 144 procedures (1-6 procedures/patient). The main indications were cholangitis (51.4 percent), choledocholithiasis (19.4 percent) and blocked stents (14.6 percent). Malignancies represented 5.6 percent of indications. The mean procedure time was 38 +/- 16 minutes. The overall success rate was 80.5 percent. Minor events occurred in 23 percent (tachycardia 13, desaturation six, transient hypotension six, self-limiting bleed four, extravasations three, and mild pancreatitis one). Major events were post sphincterotomy bleeding (five days post-procedure) one, duodenal perforation one (Billroth-II gastrectomy, survived after surgery), cholangitis two, and one death was probably procedure-related (acute myocardial event five days post-stenting in a patient with Klatskin tumour). Seven deaths occurred within one month of ERCP, due to advanced malignancies (four), sepsis (two) and acute myocardial infarction (one). Patients who died within one month had significantly higher serum urea (p-value equals 0.001), and creatinine (p-value equals 0.007) levels, and lower haemoglobin (p-value equals 0.014) level. More patients had an underlying malignancy (p-value less than 0.001). In addition, they were given significantly less conscious sedation (midazolam [p-value equals 0.002] and fentanyl [p-value equals 0.018]).
Conclusion Our study showed that ERCP is safe in an elderly Asian population. Minor complications are usually transient and related to sedation, and mortality is usually related to severity of illness and underlying malignancies.

Keywords: biliary tract diseases, elderly patients, endoscopic retrograde cholangiopancreatography, endoscopy complications
Singapore Med J 2005; 46(11): 621-626

JC Wang, AWT Tan, R Monatosh, PTK Chew
Correspondence: Dr Wang Jenn Chyuan, jennwang2003@yahoo.com

ABSTRACT
Introduction To evaluate the clinical efficiency, safety and subjective visual outcomes of multifocal intraocular lenses (IOL) in the Singapore population.
Methods This is a retrospective case series of 45 phacoemulsification with multifocal lens implantation performed in 27 patients for cataracts, over a two-year period. The efficacy, stability and safety of the lens were assessed up to six months of follow-up. A telephone interview enquiring about ratings of vision, spectacle independence, glare, driving difficulty and photic phenomena, was conducted and the results were compared with those published in the literature.
Results The best corrected distance Logmar acuity was 0.1 (0.1 and near visual acuity was N5 (range N5 to N8) at six months. The distance visual acuity stabilised by one month whereas near vision remained unchanged from day one post-surgery. Posterior capsular opacification was seen in 17 patients (38.6 percent) of which two patients (4.55 percent) required YAG capsulotomy. Total spectacle independence was achieved in 12 patients (54.4 percent). Among those who required spectacles, 50 percent required spectacles more than 50 percent of the time. Five patients (22.7 percent) reported glare usually at night (80 percent) as compared with daytime glare (20 percent). The most common photic phenomena report after surgery was halo.
Conclusion The Advanced Medical Optics ARRAY multifocal IOL showed good efficacy, predictability, stability and safety. The subjective visual outcomes in the Singapore population were comparable to those of their Western counterparts.

Keywords: ARRAY multifocal lens, cataract extraction, intraocular lens, presbyopia
Singapore Med J 2005; 46(11): 616-620

R Ganesh, T Leese
Correspondence: Dr Trevor Leese, tbleese54@hotmail.com

ABSTRACT
Introduction In most parts of the world, acute parotid abscess is a rare pathology. It occurs mainly in elderly debilitated patients and patients with oral sepsis. In Singapore, this lesion appears to be more common.
Methods We retrospectively reviewed all patients admitted to our hospital over a three-year period with parotid abscess.
Results Ten patients were treated for parotid abscess. Only two of these patients were elderly and debilitated. The remaining patients were atypical in that they were relatively young and fit with no history of oral sepsis. All the abscesses responded to simple drainage and antibiotic therapy without the need to resort to the radical drainage techniques reported historically.
Conclusion Parotid abscess is seen in an unusually young cohort of patients in Singapore. The cause for this is unclear but it may be a result of chronic oral dehydration as a consequence of our climate.

Keywords: parotid abscess, parotitis, salivary gland, suppurative parotitis
Singapore Med J 2005; 46(10): 553-556

KH Tan, TYT Tan, J Tan, I Tan, SK Chew, GSH Yeo
Correspondence: Dr Kelvin Tan Kok Hian, khtan@kkh.com.sg

ABSTRACT
Introduction To study characteristics of birth defect cases among live births, stillbirths and abortions in Singapore between 1994 and 2000.
Methods Index cases for the National Birth Defects Registry (NBDR) were obtained from all neonatal nurseries in Singapore, all hospital discharge summaries, cytogenetic and pathology reports from all pathology laboratories in Singapore, and from the compulsory reporting of all termination of pregnancy cases and stillbirths delivered. Further information was obtained from case notes retrieved from the medical record offices, antenatal clinics, cytogenetic laboratories, pathology departments and the Registry of Births and Deaths. The notified cases (live births, stillbirths and abortions) between 1994 and 2000 were extracted from the NBDR and analysed with regard to ethnicity, maternal age, trend over the seven years and types of birth defects using the British Paediatric Association Classification.
Results Between 1994 and 2000, a total of 7,870 cases (6,278 births and 1,592 abortuses) were notified, giving a rate of 23.99 birth defect cases per 1000 live births. There was a decreasing trend in birth defect incidence (19.76 to 16.85 per 1,000 live births) among live births and stillbirths and an increasing trend of abortion (3.25 to 7.57 per 1,000 live births) for birth defects. Malays had a higher rate of congenital defects at birth (24.4/1,000 live births) compared to Chinese (18.4/1,000 births). The 25-29 years age group had the lowest overall rate (22.6/1,000 live births) compared to the 19 years and below group at 31.6/1,000 live births and the 45-49 years group at 126.6/1,000 live births. The five most common groups of anomalies (per 1,000 live births) were those of heart (9.07), musculoskeletal (4.98), chromosomal (4.35), urinary (3.12) and nervous systems (2.90). The five most common aborted anomalies (per 1,000 live births) were those of chromosomal (2.40), nervous (1.23), heart (0.95), musculoskeletal (0.85) and urinary systems (0.36).
Conclusion There was an increasing trend of abortion for birth defects, accompanied by a falling trend in the congenital anomalies of live births. Both extremes of maternal age were at higher risk of non-chromosomal birth defects while advanced maternal age was at higher risk of chromosomal defects.

Keywords: abortion, birth defect, chromosome disorders, congenital abnormalities
Singapore Med J 2005; 46(10): 545-552