Letter 1: randomized clinical trial of bowel preparation with a single phosphate enema or polyethylene glycol before elective colorectal surgery (Br J Surg 2006; 93: 427-433)

The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses should be sent electronically via the BJS website (www.bjs.co.uk). All letters will be reviewed and, if approved, appear on the website. A selection of these will be edited and published in the Journal. Letters must be no more than 250 words in length.

Surgery for recurrent rectal carcinoma: The role of preoperative magnetic resonance imaging

Despite apparent curative resection of rectal carcinoma, local recurrence rates of between 3 and 32% have been reported. For those patients, radical surgical resection offers the only hope of cure. We present a review of the magnetic resonance imaging (MRI) findings and contraindications to curative surgery demonstrated using imaging.

Gangrenous cholecystitis: prediction with CT imaging

The aim of this study is to determine the usefulness of different patterns of gallbladder mucosal enhancement on contrast-enhanced computed tomography (CT) for differentiating between gangrenous and uncomplicated acute cholecystitis. This retrospective evaluation involved 56 patients with histopathologically proved acute cholecystitis (32 with gangrenous and 24 with uncomplicated acute cholecystitis) who had preoperative contrast-enhanced CT imaging. CT in 38 patients showed a gallbladder mucosal enhancement pattern that could be categorized into continuous, discontinuous, and/or irregular categories. In the other 18 patients, the mucosal enhancement pattern could not be classified due to lack of mucosal enhancement or inadequate mucosal enhancement. On contrast-enhanced CT evaluation, continuous and discontinuous and/or irregular mucosal enhancement patterns were seen in 20 and 18 patients, respectively. Among the 20 patients with continuous mucosal enhancement, 17 had uncomplicated acute cholecystitis. Seventeen of the 18 patients with discontinuous and/or irregular mucosal enhancement had gangrenous cholecystitis. The sensitivity and positive predictive value (PPV) of discontinuous and/or irregular mucosal enhancement in the diagnosis of gangrenous cholecystitis were 30.3% and 94.4% (17 of 18), respectively. The sensitivity and PPV of continuous mucosal enhancement in the diagnosis of uncomplicated acute cholecystitis were 30.3% and 85.5% (17 of 20), respectively. There was a statistically significant difference (p=0.0005) between the PPV of discontinuous and/or irregular (94.4%) and that of continuous (15%) mucosal enhancement for predicting gangrenous cholecystitis. The pattern of gallbladder mucosal enhancement on CT can be used as a reliable criterion for distinguishing acute, uncomplicated cholecystitis from gangrenous cholecystitis.

Cardiac arrest: abdominal CT imaging features

We report computed tomographic findings of two unusual cases of sudden cardiac arrest. The imaging features documented include reflux of contrast into the abdomen as indicated by opacification of renal veins, hepatic veins, inferior vena cava, and hepatic and renal parenchyma. The reflux of contrast into the portal vein in one patient has not been described in the literature. The thoracic findings were reflux of contrast into the coronary sinus, nonopacificaton of the left ventricle with intravenous contrast, and lack of cardiac motion artifact.

Ultrasound-guided transthoracic co-axial biopsy of thoracic mass lesions

PURPOSE

To compare the diagnostic yield of fine-needle aspiration biopsy (FNAB) and cutting needle biopsy in thoracic lesions.

MATERIAL AND METHODS

Thirty patients with thoracic mass lesions were subjected to ultrasound-guided co-axial FNAB and cutting needle biopsy using 0.7 mm aspirating and 1.0-mm cutting needles, respectively. The diagnostic yield of the individual modalities was compared with the combined yield.

RESULTS

A conclusive diagnosis was obtained in 76.6% (n=23) of patients by FNAB and in 66.6% (n=20) by cutting needle biopsy. The combined diagnostic yield of FNAB and cutting needle biopsy was 93.3% (n=28) with a significant statistical difference (p<0.03) as compared to cutting biopsy alone. Of the patients, 23.2% (n=7) had benign and 76.6% (n=23) malignant aetiologies. The diagnostic yield of FNAB versus cutting needle biopsy in benign lesions was 57.1% (n=4) and 100% (n=7), respectively. The diagnostic yield of FNAB versus cutting needle biopsy in malignant lesions was 82.6% (n=19) and 56.5%, (n=13). Two patients remained undiagnosed by either modality. There were no complications.

CONCLUSION

FNAB and cutting needle biopsy are complementary to each other and attempts should be made to obtain small tissue cores in addition to routine cytologic specimens in diagnosing thoracic lesions, especially in benign pathologies. US provides a safe guidance modality for lesions abutting the chest wall.

Pressure modulates monocyte migration

Migration of monocytes into the subendothelial space of the aorta has been considered to be an important event in the development of atherosclerosis. Because hypertension is commonly associated with atherosclerosis, we studied the effect of applied pressure on the migration of monocytes. Direct applied pressure increased the migration (P < .001) of monocytes across a filter when compared with normal atmospheric pressure. The migration of monocytes was found to be directly related to the amount of the applied pressure. Amlodipine, a calcium channel blocker, attenuated the migration of monocytes under normal as well as increased pressure conditions in a dose-dependent manner. These studies provide a basis to speculate on the role of direct pressure in the migration of monocytes into the subendothelial space and the possibility that vasoactive agents may modulate the migration of monocytes independent of their pressure-lowering effect.

Anorectal melanoma--an incurable disease?

PURPOSE

This study was designed to describe recurrence and survival rates after operative treatment for anorectal melanoma and to identify predictive factors for recurrence.

METHODS

Records of 50 patients with anorectal melanoma from 1939 to 1993 were reviewed.

RESULTS

Overall five-year survival and disease-free survival were 22 and 16 percent, respectively. At the time of diagnosis, 26 percent of patients had metastatic disease, and all died within 12 (mean, 6.3) months. Five-year survival and recurrence rates were identical after either abdominoperineal resection (APR) or wide local excision, both with curative intent. Gender, size of tumor, presence of melanin, positive perirectal lymph nodes, or treatment were not predictive of recurrence. Anorectal melanoma was found incidentally after hemorrhoidectomy or polypectomy in five patients. Three other patients underwent an excisional biopsy of a lesion measuring less than 2 cm. Of these eight patients, five underwent APR and three underwent wide local excision with no microscopic residual tumor at pathology. All developed regional or systemic recurrence at a mean of 21 (range, 4-88) months, and all died of their disease at a mean of 29 (range, 5-98) months.

CONCLUSION

Prognosis for anorectal melanoma is poor, irrespective of surgical treatment performed. No predictive factors for recurrence were identified in this series. Wide local excision with a negative margin of a least 1 cm is suggested as the treatment of choice. APR should be reserved for tumor not amenable to local excision or for palliative treatment of large obstructive lesion until effective adjuvant therapies are available.

Risk-adjusted analysis of surgeon performance: a 1-year study

A 1-year prospective analysis was undertaken of all non-day-case general surgery in a district general hospital. Using the Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) scoring system 3004 patients were assessed. From the predictions of mortality and morbidity so obtained, a quality measure, the ratio of observed to expected numbers of deaths and complications (O:E ratio) was determined for each surgeon, both overall and within specialty zones. The present study demonstrates the serious hazard in using 'raw' uncorrected mortality and morbidity statistics to compare surgeon performance. Mortality rates varied from 1.0 to 4.9 per cent whereas O:E ratios ranged from 0.83 to 1.06; morbidity rates varied from 5.3 to 12.6 per cent with O:E ratios 0.86-1.02. Great misunderstanding may result from the publication of surgeon or hospital 'league tables'. The present study demonstrates a technique that might allow surgeon performance to be monitored adequately and accurately.

The effects of major abdominal surgery, enteral and parenteral nutrition on pancreatic function and morphology

The effects of major abdominal surgery and nutritional support upon pancreatic function and morphology were studied in similar groups of patients who underwent major abdominal surgery (n = 18), received parenteral nutritional support (n = 18) or received enteral nutritional support (n = 16). The exocrine function of the pancreas was measured by means of an oral pancreatic function test (using 1 g of N-benzoyl-L-tyrosyl para-aminobenzoic acid) with measurement of serum para-aminobenzoic acid at 3 h and the Pancreatic Excretion Index. Pancreatic morphology was assessed by real time ultrasound and a pancreatic size index was calculated (maximum diameter of head x body). Serial measurements of function and morphology were carried out in each patient at entry into the study and at 7 and 14 days after operation or start of nutritional support. Serum PABA levels were similar in the 3 groups at the start of the study. Although the levels remained unchanged in the enteral and parenteral groups, a significant and progressive decrease was observed in the surgical group (serum PABA = 27.5 nmol/l (24.0-30.6) before operation, 10.5 nmol/l (5.5-13.4) 14 days after operation, P < 0.01). No significant changes in pancreatic size were seen. Parenteral and enteral nutrition preserves pancreatic exocrine function. A dramatic reduction in pancreatic exocrine function is seen after major abdominal surgery.

The prevalence of gut translocation in humans

BACKGROUND/AIMS

Gut translocation of enteric organisms across the intact intestinal mucosa has been postulated as a potential source of sepsis in susceptible patients. However, little is known of its occurrence or significance in humans. The aim of this study was to determine the prevalence of gut translocation of bacteria in humans and attempt to identify any predisposing factors to its occurrence.

METHODS

A consecutive series of 267 general surgical patients were examined for evidence of bacterial translocation by bacterial analysis of intestinal serosa and mesenteric lymph nodes taken at the time of surgery.

RESULTS

Translocation occurred in 10.3% of patients overall. Both aerobic and anaerobic bacteria translocated. Excluding patients with distal intestinal obstruction and those with inflammatory bowel disease in whom translocation was more common, the prevalence was 5%. Neither jaundice, nutritional status, nor total parenteral nutrition predisposed to translocation. Similarly, mucosal atrophy did not predispose to this phenomenon. The development of postoperative septic complications was twice as common in patients with translocation as in those without, but mortality was unaffected.

CONCLUSIONS

Translocation occurs as a spontaneous event in humans, but its clinical significance remains to be defined.

p53 expression and K-ras mutation in colorectal adenomas

The frequency of p53 overexpression and K-ras codon 12 mutation was investigated in a series of colorectal adenomas. p53 was detected by immunohistochemistry in only 5% of tumours, whereas K-ras mutation was found in eight of 30 adenomas examined. In vitro, mutant p53 and ras genes cooperate to transform primary rat cells into a tumourigenic cell line. The presence of both p53 overexpression and K-ras mutation in a benign tubulovillous polyp in the present series suggests that in vivo this combination of events is insufficient to cause malignant transformation of a large bowel adenoma.

Prognostic value of p53 overexpression and c-Ki-ras gene mutations in colorectal cancer

BACKGROUND

Mutations in Ki-ras codon 12 and the p53 gene are common abnormalities in colorectal cancer. The occurrence of p53 overexpression and/or Ki-ras codon 12 mutations were analyzed in 100 colorectal adenomas to determine if they were related to patient survival.

METHODS

p53 overexpression was identified by immunohistochemistry, and Ki-ras codon 12 mutations were detected using the polymerase chain reaction and a restriction enzyme digestion method.

RESULTS

p53 overexpression was identified in 45% of tumors, with a higher frequency identified in DNA aneuploid and left-sided tumors than in DNA diploid and right-sided tumors. Mutations in Ki-ras codon 12 were identified in 24% of carcinomas. Individually, mutations in Ki-ras codon 12 or p53 overexpression were not prognostic indicators of survival. However, a statistically significant difference in survival was identified when these two oncogenic abnormalities were analyzed together. The median survival of patients whose tumors contained both oncogenic abnormalities was less than half of that of patients with either alteration alone or without either abnormality.

CONCLUSIONS

Screening for multiple genetic abnormalities in colorectal cancers excised at surgery may prove to be a useful tool in determining prognosis.

Cerebral ammonia levels and enzyme changes during Plasmodium yoelii infection in mice

Ammonia, lactate and glutamate levels and the activities of glutamine synthetase (GS), glutamate dehydrogenase (GDH), glutaminase (GLN), aspartate transaminase (AST), phosphofructokinase (PFK) and monoamine oxidase (MAO) were compared in the brain tissue of normal and P. yoelii infected mice. The brain lactate increased by 96% at peak parasitaemia. Cerebral ammonia also exhibited an increase in infected mice which was parasitaemia dependent, while glutamate remained almost unchanged. The brain glutamine synthetase registered an increase of 35% (P < 0.001) in post-mitochondrial fractions, this effect being perceptible even at low parasitaemia, but attained constancy at parasitaemia levels higher than 20%. The activity of monoamine oxidase and phosphofructokinase increased by 105% (P < 0.02) and 41% (P < 0.05) respectively while glutamate dehydrogenase decreased by 15% (P < 0.001). Glutaminase and aspartate transaminase were not significantly influenced by infection (tested only at high parasitaemia levels). It has been postulated that cerebral hypoxia and aberrations in ammonia metabolism may both contribute towards malaria induced cerebral complications.